The ESC Textbook of Cardiovascular Imaging [3 ed.] 0198849354, 9780198849353

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The ESC Textbook of

Cardiovascular Imaging

EUROPEAN SOCIETY OF CARDIOLOGY PUBLICATIONS The ESC Textbook of Cardiovascular Medicine (Third Edition) Edited by A. John Camm, Thomas F. Lüscher, Gerald Maurer, and Patrick W. Serruys The ESC Textbook of Preventive Cardiology Edited by Stephan Gielen, Guy De Backer, Massimo Piepoli, and David Wood The EHRA Book of Pacemaker, ICD, and CRT Troubleshooting: Case-​based learning with multiple choice questions Edited by Harran Burri, Carsten Israel, and Jean-​Claude Deharo The EACVI Echo Handbook Edited by Patrizio Lancellotti and Bernard Cosyns The ESC Handbook of Preventive Cardiology: Putting prevention into practice Edited by Catriona Jennings, Ian Graham, and Stephan Gielen The EACVI Textbook of Echocardiography (Second Edition) Edited by Patrizio Lancellotti, José Luis Zamorano, Gilbert Habib, and Luigi Badano The EHRA Book of Interventional Electrophysiology: Case-​based learning with multiple choice questions Edited by Hein Heidbuchel, Matthias Duytschaever, and Harran Burri The ESC Textbook of Vascular Biology Edited by Robert Krams and Magnus Bäck The ESC Textbook of Cardiovascular Development Edited by José Maria Pérez-​Pomares and Robert Kelly The EACVI Textbook of Cardiovascular Magnetic Resonance Edited by Massimo Lombardi, Sven Plein, Steffen Petersen, Chiara Bucciarelli-​Ducci, Emanuela R. Valsangiacomo Buechel, Cristina Basso, and Victor Ferrari The ESC Textbook of Sports Cardiology Edited by Antonio Pelliccia, Hein Heidbuchel, Domenico Corrado, Mats Börjesson, and Sanjay Sharma The ESC Handbook of Cardiac Rehabilitation Edited by Ana Abreu, Jean-​Paul Schmid, and Massimo Piepoli The ESC Textbook of Intensive and Acute Cardiovascular Care (Third Edition) Edited by Marco Tubaro, Pascal Vranckx, Eric Bonnefoy-Cudraz, Susanna Price, and Christiaan Vrints The ESC Textbook of Cardiovascular Imaging (Third Edition) Edited by José Luis Zamorano, Jeroen J. Bax, Juhani Knuuti, Patrizio Lancellotti, Fausto J. Pinto, Bogdan A. Popescu, and Udo Sechtem

The ESC Textbook of

Cardiovascular Imaging THIRD EDITION EDITED BY

José Luis Zamorano Jeroen J. Bax Juhani Knuuti Patrizio Lancellotti Fausto J. Pinto Bogdan A. Popescu Udo Sechtem

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3 Great Clarendon Street, Oxford, OX2 6DP, United Kingdom Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries © European Society of Cardiology 2021 The moral rights of the authors have been asserted First Edition published in 2010 Second Edition published in 2015 Third Edition published in 2021 Impression: 1 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by licence or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this work in any other form and you must impose this same condition on any acquirer Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016, United States of America British Library Cataloguing in Publication Data Data available Library of Congress Control Number: 2020949297 ISBN 978–​0–​19–​884935–​3 DOI: 10.1093/​med/​9780198849353.001.0001 Printed in Great Britain by Bell & Bain Ltd., Glasgow Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check the product information and clinical procedures with the most up-​to-​date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The authors and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work. Except where otherwise stated, drug dosages and recommendations are for the non-​pregnant adult who is not breast-​feeding Links to third party websites are provided by Oxford in good faith and for information only. Oxford disclaims any responsibility for the materials contained in any third party website referenced in this work.

​Preface

With great pleasure we would like to introduce the third edition of The ESC Textbook of Cardiovascular Imaging. Cardiovascular imaging is the cornerstone of non-​invasive diagnosis in cardiology. The continuous development of all techniques implies the need for continuous medical education. The third edition of The ESC Textbook of Cardiovascular Imaging includes new and updated chapters that explain the utility of the different imaging modalities in the diagnosis of all relevant and major cardiovascular diseases. The clinically oriented text is accompanied by images and insights of the everyday practice of these techniques, prepared by experienced and well-​known cardiovascular imagers who have dedicated long hours and commitment to prepare the chapters included in this edition. We hope that cardiologists, trainees, and cardiovascular imagers find in this book the knowledge and expertise to cope with the challenges faced in their daily practice.

As editors, we have tried to harmonize all chapters in order to obtain an easy reading of all chapters. Images were carefully selected to better understand the text. On behalf of all the editors, we would like to express our gratitude to all authors and to Claudia Balseca as Editors’ Assistant. All of them worked extremely hard to make this third book possible. We want to dedicate our work to the victims of COVID-​19 and their families, especially to our beloved friend Prof Maurizio Galderisi, who was a co-​author in this book. José Luis Zamorano Jeroen J. Bax Juhani Knuuti Patrizio Lancellotti Fausto J. Pinto Bogdan A. Popescu Udo Sechtem

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Individual purchasers of this book are also entitled to free personal access to the online edition for 5 years via oxfordmedicine.com/esccvimaging3. Please refer to the access token for instructions on token redemption and access. Accessing this content online allows you to print, save, cite, email, and share content; download high-resolution figures as PowerPoint® slides; save often-used books, chapters, or searches; annotate; and quickly jump to other chapters or related material on a mobile-optimized platform.

Contents

Symbols and abbreviations  Contributors xv

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SECTION 1 Technical aspects of imaging 

1 Conventional echocardiography—​basic principles  3 Andreas Hagendorff, Stephan Stobe, and Bhupendar Tayal



2 Nuclear cardiology (PET and SPECT)—​basic principles  41 Danilo Neglia, Riccardo Liga, Stephan G. Nekolla, Frank M. Bengel, Ornella Rimoldi, and Paolo G. Camici



3 Cardiac CT—​basic principles  57 Gianluca Pontone and Filippo Cademartiri



4 CMR—​basic principles  67 Jan Bogaert, Rolf Symons, and Jeremy Wright



5 Training and competence in cardiovascular imaging  79 Kevin Fox and Marcelo F. Di Carli

SECTION 2 New technical developments in imaging techniques  6 New developments in echocardiography/​ Advanced echocardiography  87 6.1 Three-​dimensional echocardiography   87 Silvia Gianstefani and Mark J. Monaghan

6.2 Assessment of myocardial function by speckle-​tracking echocardiography   103 Thor Edvardsen, Lars Gunnar Klaeboe, Ewa Szymczyk, and Jarosław D. Kasprzak

7 Contrast echocardiography  111 Roxy Senior, Harald Becher, Fausto J. Pinto, and Rajdeep S. Khattar 8 Echocardiography in the cath lab: Fusion imaging and use of intracardiac echocardiography  121 Covadonga Fernández-​Golfín and José Luis Zamorano 9 New technical developments in nuclear cardiology and hybrid imaging  129 Antti Saraste, Sharmila Dorbala, and Juhani Knuuti 10 New technical developments in Cardiac CT: Anatomy, fractional flow reserve (FFR), and machine learning  145 Stephan Achenbach, Jonathan Leipsic, and James Min

SECTION 3 Valvular heart disease  11 Aortic valve stenosis  161 Philippe Pibarot, Helmut Baumgartner, Marie-​Annick Clavel, Nancy Côté, and Stefan Orwat 12 Aortic valve regurgitation  181 Julien Magne and Patrizio Lancellotti 13 Mitral valve stenosis  191 Ferande Peters and Eric Brochet 14 Mitral valve regurgitation  199 Daniel Rodríguez Muñoz, Kyriakos Yiangou, and José Luis Zamorano

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C onte n ts

16 Multiple and mixed valvular heart disease  223 Philippe Unger and Madalina Garbi

27 Nuclear cardiology and detection of coronary artery disease  403 Richard Underwood, James Stirrup, and Danilo Neglia



17 Intraoperative transoesophageal echocardiography for valvular surgery  233 Joseph F. Maalouf and Hector I. Michelena

28 PET-​CT and detection of coronary artery disease  421 Marcelo F. Di Carli



29 MDCT and detection of coronary artery disease  435 Stephan Achenbach and Pál Maurovich-​Horvat



30 CMR and detection of coronary artery disease  447 Eike Nagel, Juerg Schwitter, and Sven Plein



31 Non-invasive Imaging of the vulnerable atherosclerotic plaque  467 Rong Bing, David E. Newby, Jagat Narula, and Marc R. Dweck



32 Imaging of microvascular disease  481 Paolo G. Camici and Ornella Rimoldi

15 Tricuspid and pulmonary valve disease  211 Denisa Muraru and Elif Leyla Sade

18 Valvular prostheses  251 Luigi P. Badano and Denisa Muraru 19 Endocarditis  271 Daniel Rodríguez Muñoz and Álvaro Marco del Castillo

SECTION 4 Procedures in the intensive cardiovascular care unit  20 Imaging- guided transseptal puncture and transcatheter closure of patent foramen ovale/ atrial septal defect, ventricular septal defect, and paravalvular leaks  287 Itzhak Kronzon, Juan Manuel Monteagudo, Francesco F. Faletra, Priti Mehla, and Muhamed Saric 21 Imaging for electrophysiological procedures  303 Louisa O’Neill, Iain Sim, John Whitaker, Steven Williams, Henry Chubb, Pál Maurovich-​Horvat, Mark O’Neill, and Reza Razavi 22 Transcatheter aortic valve implantation  315 Arnold C.T. Ng, Victoria Delgado, and Jeroen J. Bax 23 Transcatheter mitral valve interventions  337 Nina C. Wunderlich, Robert J. Siegel, Ronak Rajani, and Nir Flint 24 Transcatheter tricuspid valve repair/​ replacement  361 Rebecca T. Hahn 25 Transcatheter pulmonic valve replacement  377 Kuberan Pushparajah and Alessandra Frigiola

SECTION 5 Coronary artery disease 

26 Echocardiography and detection of coronary artery disease  395 Thor Edvardsen, Marta Sitges, and Rosa Sicari

SECTION 6 Heart failure  33 Evaluation of systolic LV function and LV mechanics  497 Rainer Hoffmann and Frank A. Flachskampf 34 Evaluation of left ventricular diastolic function  507 Bogdan A. Popescu, Carmen C. Beladan, and Maurizio Galderisi† 35 Imaging of the right heart  519 Lawrence Rudski, Petros Nihoyannopoulos, and Sarah Blissett 36 Assessment of viability  545 Luc A. Pierard, Paola Gargiulo, Pasquale Perrone-​Filardi, Bernhard Gerber, and Joseph B. Selvanayagam 37 Imaging cardiac innervation  565 Albert Flotats and Ignasi Carrió 38 Cardiac resynchronization therapy: Selection of candidates  577 Victoria Delgado and Jens-​Uwe Voigt 39 Cardiac resynchronization therapy: Optimization and follow-​up  587 Marta Sitges and Erwan Donal

C on t e n ts 40 Echocardiography evaluation in extracorporeal support  599 Susanna Price and Alessia Gambaro 41 Cardiac imaging in cardio-​oncology  613 Riccardo Asteggiano, Patrizio Lancellotti, Maurizio Galderisi†, Stephane Ederhy, and Marie Moonen

48 Myocarditis  715 Ali Yilmaz, Heiko Mahrholdt, and Udo Sechtem 49 Cardiac masses and tumours  731 Teresa López-​Fernández and Peter Buser

SECTION 9 Aortic disease: aneurysm and dissection 

SECTION 7 Cardiomyopathies  42 Hypertrophic cardiomyopathy  629 Nuno Cardim, Alexandra Toste, and Robin Nijveldt 43 Infiltrative cardiomyopathy  645 Massimo Lombardi, Silvia Pica, Antonella Camporeale, Alessia Gimelli, and Dudley J. Pennell 44 Dilated cardiomyopathy  661 Upasana Tayal, Sanjay Prasad, Tjeerd Germans, and Albert C. van Rossum 45 Other genetic and acquired cardiomyopathies  681 Kristina Haugaa and Perry Elliott

SECTION 8 Peri-​myocardial disease  46 Pericardial effusion and cardiac tamponade  697 Allan Klein, Bernard Cosyns, and Aldo L. Schenone 47 Constrictive pericarditis  707 Alida L.P. Caforio, Maurizio Galderisi†, Massimo Imazio, Renzo Marcolongo, Yehuda Adler, and Ciro Santoro



50 The role of echocardiography  747 Arturo Evangelista and Gisela Teixidó-​Turà



51 Aortic disease: Aneurysm and dissection—​role of CMR  757 Jose F. Rodriguez-​Palomares and Arturo Evangelista



52 Aortic disease: Aneurysm and dissection—​role of MSCT  771 Rocío Hinojar and Raimund Erbel

SECTION 10 Adult congenital heart disease  53 The role of echocardiography in adult congenital heart disease  783 Lindsay A. Smith, Mark K. Friedberg, and Luc Mertens 54 The role of CMR and MSCT  809 Giovanni Di Salvo and Francesca R. Pluchinotta

Index 

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ix

Symbols and abbreviations

z video E cross reference 9 additional online material M website AC arrhythmogenic cardiomyopathy/​attenuation correction AccT acceleration time ACE angiotensin-​converting  enzyme ACR American College of Radiology ACS acute coronary syndromes AF atrial fibrillation åICD implantable cardioverter defibrillator Ar atrial re­verse velocity AR aortic regurgitation ARVC arrhythmogenic right ventricular cardiomyopathy AS aortic stenosis ASD atrial septal defect ASE American Society of Echocardiography ASO amplatzer septal occluder AV aortic valve/​atrial valve AVA aortic valve area AVS aortic valve stenosis BAV bicuspid aortic valve BMI body mass index BNP B-​type natriuretic peptide BSA body surface area CAC coronary artery calcium CAD coronary artery disease CAV cardiac allograft vasculopathy CBF coronary blood flow CCT cardiac computed tomography CCTA coronary computed tomography angiography CFR case fatality rate/​coronary flow reserve CHF congestive heart failure CIED cardiac implantable electrical devices CLT Classroom and Laboratory Training CM contrast material CMD coronary microvascular dysfunction

CMR CPT CRT CSA CT CTA CTCA CTP CW CWD CZT DECT DOPS DSCT DSE EACTS EACVI EAM EANM EAPC ECMO ECNC ECV ED ED EDIC EDT EDV EF EOA EPIC ERO EROA ESC ESCR ESCR ESV

cardiac magnetic resonance cold pressure testing cardiac resynchronization therapy cross-​sectional  area computed tomography computed tomography angiography computed tomography coronary angiography computed tomography myocardial perfusion colour wave/​continuous wave colour wave Doppler cadmium zinc telluride dual-​energy computed tomography Direct Observation of Practical Skills dual-​source computed tomography dobutamine stress echocardiography European Association for Cardio-​Thoracic Surgery European Association of Cardiovascular Imaging electro-​anatomical mapping European Association of Nuclear Medicine European Association of Preventive Cardiology extracorporeal membrane oxygenation European Council of Nuclear Cardiology extracellular volume effective radiation dose external diameter Echo Dobutamine International Cooperative E wave decel­eration time end-​diastolic  volume ejection fraction effective orifice area Echo-​Persantine International Cooperative effective regurgitant orifice effective regurgitant orifice area European Society of Cardiology European Society of Cardiac Radiology European Society of Cardiovascular Radiology end-​systolic  volume

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Symb ols an d Abbreviations EVEREST FAC FBP FF FFA FFR FO FOV FWLS GCV GLS GLS HCM HF HFA HFpEF HLA HR HU HVD IAEA ICA ICU IDR INCAPS IOD IRIS IVC IVRT IVUS LA LA LAA LAD LAP LAV LAVi LBBB LD LDL LGE LMV LOR LS LV LVAD LVFP LVEDD LVEDP LVEF LVESV LVOT MACE

Endovascular Valve Edge-​to-​Edge REpair Study fractional area change filtered back-​projection forward flow free fatty acid fractional flow reserve fossa ovalis field of view free wall longitudinal strain GREAT cardiac vein global longitudinal left ventricular strain global longitudinal strain hypertrophic cardiomyopathy heart failure Heart Failure Association heart failure with preserved ejection fraction horizontal long axis heart rate Hounsfield Units heart valve disease International Atomic Energy Agency invasive coronary angiography intensive care unit iodine delivery rate IAEA Nuclear Cardiology Protocols Cross-​Sectional  Study internal orifice diameter iterative reconstruction in image space inferior vena cava isovolumic relaxation time intravascular ultrasound left atrium long axis left atrial appendage left anterior descending left atrial pressure left atrial volume LA volume indexed to body surface area left bundle branch block left disc low-​density lipoprotein late gadolinium enhancement left marginal vein line-​of response longitudinal strain left ventricle left ventricular assistance device left ventricular filling pressure left ventricle end-​diastolic dimension left ventricular end-diastolic pressure left ventricular ejection fraction left ventricular end-​systolic volume left ventricular outflow tract major adverse cardiovascular events

MAD MAPSE MBF MCE MCQ MDCT MESA MFR MI MI MIP MPI MPRI MR MRA MRCA MRI MS MV MVA MVO NASCI NBE NMR NYHA OCT OR PA PAH PAP PASP PCWP PE PET PFO PH PHT PISA PIV PLARC PPL PR PS PSF PSIR PSS PV PVI PVLV PVR PW

mitral annular disjunction mitral annular plane systolic excursion myocardial blood flow myocardial contrast echocardiography multiple choice question multidetector-​row computed tomography Multi-​Ethnic Study of Atherosclerosis myocardial flow reserve mechanical index myocardial infarction maximum intensity projections myocardial performance index/​myocardial perfusion imaging myocardial perfusion reserve index mitral regurgitation magnetic resonance angiography magnetic resonance coronary angiography magnetic resonance imaging mitral stenosis mitral valve mitral valve area microvascular obstruction North American Society for Cardiovascular Imaging National Board of Echocardiography nuclear magnetic resonance New York Heart Association optical coherence tomography operating room pulmonary artery pulmonary arterial hypertension pulmonary arterial pressure pulmonary artery systolic pressure pulmonary capillary wedge pressure pulmonary embolism positron emission tomography patent foramen ovalis pulmonary hypertension pressure half-​time proximal isovelocity surface area posterior interventricular vein paravalvular Leak Academic Research Consortium referred to as periprosthetic leak pulmonary regurgitation pulmonary stenosis point spread function phase-​sensitive inversion recovery post-​systolic shortening pulmonary valve pulmonary vein isolation posterior vein of the left ventricle pulmonary vascular resistance pulsed wave

Sym b ol s a n d A b b rev iat i on s QA RA RAP RCA RD RF RF RIMP ROI ROS RPM RV RVAD RVEF RVOT RVSP SAM SARF SCCT SCD SCMR SD SE SHD SL SNR SPAMM SPECT SRD SSFP

quality assurance right artery right atrial pressure right coronary artery right disc regurgitant flow regurgitant fraction right-​sided index of myocardial performance region of interest reactive oxygen species revolutions per minute right ventricle right ventricular assist device right ventricular ejection fraction right ventricular outflow tract right ventricular systolic pressure systolic anterior motion severe acute respiratory failure Society of Cardiovascular Computed Tomography sudden cardiac death Society for Cardiovascular Magnetic Resonance standard deviation stress echocardiography structural heart disease septal leaflet signal-​to-​noise  ratio spatial modulation of magnetization single photon emission computed tomography sewing ring diameter steady-​state free precession

STE SV SVC TA TAC TAD TAPSE TAVI TAVR TOE TI TOF TOF TR TTDE TV USPIO VA VAD VC VHD VLA VSD VT VT VTI WISE

speckle tracking echocardiography stroke volume superior vena cava tricuspid annular time-​activity  curves tissue annulus diameter tricuspid annular plane systolic excursion transcatheter aortic valve implantation transcatheter aortic valve replacement transoesophageal echocardiography the optimal inversion tetralogy of Fallot time of flight tricuspid regurgitation the feasibility of transthoracic doppler echocardiography tricuspid valve ultrasmall superparamagnetic iron oxide ventricular arrhythmias ventricular assist device vena contracta valvular heart disease vertical long axis ventricular septal defect velocity time ventricular tachycardia velocity-​time integral Women’s Ischemia Syndrome Evaluation

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Contributors

Stephan Achenbach Department of Cardiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany

Frank M. Bengel, MD, Univ. Prof. Dr. med. Director, Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany

Yehuda Adler The Gertner Institute, Sheba Medical Center, affiliated to Sackler Medical School, Tel Aviv University and the College for Academic Studies, Tel Aviv, Israel

Rong Bing, MBBS Doctor, Department of Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK

Riccardo Asteggiano, MD, FESC Adjunct Professor, Faculty of Medicine, Insubria University, Varese, Italy; LARC (Laboratorio Analisi e Ricerca Clinica), Turin, Italy Luigi P. Badano, MD, PhD, FESC, FACC, Honorary FASE, Honorary FEACVI Professor of Cardiovascular Medicine, University of Milano-​ Bicocca; Director of the Cardiovascular Imaging Unit, Department of Cardiovascular, Neural and Metabolic Sciences; Istituto Auxologico Italiano, IRCCS, Milano, Italy; Istituto Auxologico Italiano, IRCCS, Cardiology Unit, Department of Cardiovascular, Neural and Metabolic Sciences, San Luca Hospital, and Department of Medicine and Surgery, University of Milano-​Bicocca, Piazzale Brescia, MI, Italy Helmut Baumgartner, MD Department of Cardiology III, Adult Congenital and Valvular Heart Disease, University Hospital Muenster, Muenster, Germany Jeroen J. Bax, MD, PhD Professor of Cardiology, Head Department of Non-invasive Imaging, Leiden University Medical Center, The Netherlands Harald Becher, MD, PhD, FRCP Professor of Medicine, ABACUS, Mazankowski Alberta Heart Institute, University of Alberta Hospital, Edmonton, Alberta, Canada Carmen C. Beladan, MD, PhD University of Medicine and Pharmacy ‘Carol Davila’—​ Euroecolab, Emergency Institute for Cardiovascular Diseases ‘Prof. Dr. C. C. Iliescu’, Bucharest, Romania

Sarah Blissett, MD, MHPE Cardiologist, London Health Sciences Centre, London, Canada; Assistant Professor (Medicine), Western University, London, Canada; Researcher, Centre for Education Research and Innovation, Schulich School of Medicine and Dentistry, Western University, London, Canada Jan Bogaert, MD, PhD Faculty of Medicine, Department of Imaging and Pathology, University Hospitals Leuven, Leuven, Belgium Eric Brochet Department of Cardiology, University Hospital Bichat, Paris, France Peter Buser, MD Department of Cardiology, University Hospital Basel, Basel, Switzerland Filippo Cademartiri, MD, PhD Chairman Prof. Dr., Department of Radiology, Area Vasta 1—​ ASUR Marche, Urbino, PU, Italy Alida L.P. Caforio, MD, PhD, FESC Cardiologist, Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, Padova, Italy Paolo G. Camici, MD, FESC, FAHA, FACC, FRCP Professor of Cardiology, Department of Cardiovascular Research Center, San Raffaele Hospital and Vita Salute University, Milan, Italy Antonella Camporeale, MD, PhD Multimodality Cardiac Imaging Section, I.R.C.C:S., Policlinico San Donato, Milan, Italy

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C ontribu tors Nuno Cardim, MD, PhD Head Echo Lab, Department of Cardiology, Hospital da Luz, Lisbon, Portugal

Thor Edvardsen, MD, PhD Professor, Department of Cardiology, Oslo University Hospital, Oslo, Norway

Ignasi Carrió, MD, FEBNM, FESC, FRCP Professor of Nuclear Medicine, Universitat Autònoma de Barcelona, Director, Nuclear Medicine Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain

Perry Elliott Chair of Cardiovascular Medicine, University College London, London, UK

Henry Chubb Division of Pediatric Cardiology, Department of Pediatrics, Stanford University, USA Marie-​Annick Clavel, DVM, PhD Associate Professor, Department of Medicine, Laval University, Canada Research Chair on Women’s Valvular Heart Health, Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada Bernard Cosyns, MD, PhD, FESC, FEACVI Cardiology Department, Centrum voor hart en vaatziekten, Universitair ziekehuis Brussel, 101 laarbeeklaan 1090 Brussels, Belgium Nancy Côté, PhD Institut Universitaire de cardiologie te de Pneumologie de Québec, Québec, Canada Álvaro Marco del Castillo, MD  Victoria Delgado, MD, PhD Cardiologist, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands Marcelo F. Di Carli, MD Executive Director, Cardiovascular Imaging, Department of Radiology and Medicine, Brigham and Women’s Hospital, Boston, MA, USA, and Family Professor of Radiology and Medicine, Women’s Hospital, Seltzer, Harvard Medical School, Boston, MA, USA

Raimund Erbel, MD, FAHA, FESC, FASE, FACC Medical Informatics, Biometry and Epidemiology, University Clinic, Universitat Duisburg-Essen, Essen, Germany Arturo Evangelista, MD, FESC Institut de Recerca Vall d’Hebron (VHIR), Coordinator of Valvular and Aortic Research Unit, Hospital Universitari Vall d’Hebron, Barcelona, Spain Francesco F. Faletra, MD Director of Cardiac Imaging Service, Cardiocentro Ticino Lugano, Switzerland Covadonga Fernández-​Golfín, MD Cardiac Imaging Unit Coordinator, Cardiology Department, Ramón y Cajal University Hospital, Madrid, Spain Frank A. Flachskampf, MD, FESC, FACC Professor, Department of Medical Sciences, Uppsala University, Uppsala, Sweden Nir Flint, MD Attending Cardiologist, Echocardiography Lab, Division of Cardiology, Tel-​Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-​Aviv University, Tel-​Aviv, Israel Albert Flotats, MD Consultant, Department of Nuclear Medicine, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain Kevin Fox, MD, FRCP, FESC Consultant Cardiologist, Department of Cardiology, Imperial College Healthcare NHS Trust, London, Middlesex, UK

Giovanni Di Salvo, MD, PhD, MSc, FESC, FEACVI, FISC Professor and Director, Department of Paediatric Cardiology and Congenital Heart Disease, University of Padua, Padua, Italy; Honorary Consultant Royal Brompton Hospital, London, UK

Mark K. Friedberg, MD Professor, The Hospital for Sick Children, The University of Toronto, Toronto, ON, Canada

Erwan Donal, MD, PhD Cardiology & INSERM1099, University Hospital, University Rennes-​1,  France

Alessandra Frigiola, MD, MD(res), FRCP Consultant Cardiologist—​ACHD specialist, Cardiovascular, ACHD, Guy’s & St Thomas’ Hospital, NHS Foundation Trust, London, UK

Sharmila Dorbala, MD Division of Nuclear Medicine, Department of Radiology, Brigham and Women’s Hospital, Boston, MA, USA Marc R. Dweck, MD, PhD Professor, Department of BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK Stephane Ederhy Department of Cardiology, AP-HP, Saint-Antoine Hospital, Sorbonne University, Paris, France

Maurizio Galderisi, MD† Professor of Medicine, Department of Advanced Biomedical Sciences, Federico II University Hospital, Naples, Italy Alessia Gambaro, MD Cardiology Division, Department of Medicine, University of Verona, Verona, Italy Madalina Garbi, MD, MA Consultant Cardiologist, Department of Cardiology, Royal Papworth Hospital, Cambridge, UK

C on t ri bu tor s Paola Gargiulo, MD, PhD Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy

Itzhak Kronzon, MD, FASE, FESC, FACC, FAHA, FCCP Professor of Cardiovascular Medicine, Hofstra University, NY, USA

Bernhard Gerber, MD, PhD, FESC, FACC, FAHA Professor of Medicine, Cardiology Division, Department of Cardiovascular Diseases, Cliniques Universitaires St. Luc UC Louvain, Brussels, Belgium

Patrizio Lancellotti Professor, Head of Department, Department of Cardiology, University of Liège Hospital, Liège, Belgium

Tjeerd Germans, MD, PhD Cardiologist, Department of Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands Silvia Gianstefani, MD  Alessia Gimelli, MD Fondazione Toscana Gabriele Monasterio, Pisa, Italy Andreas Hagendorff, MD Professor, Department of Cardiology, University Hospital Leipzig, Leipzig, Germany  Rebecca T. Hahn, MD, FESC Department of Medicine, Division of Cardiology/​New York Presbyterian Hospital, New York-​Presbyterian/​Columbia University Medical Center, New York, NY, USA Kristina Haugaa, MD  Rocío Hinojar, MD Ramón y Cajal University Hospital, Madrid, Spain Rainer Hoffmann, MD Professor, Department of Cardiology, Bonifatius Hospital Lingen, Lingen, Germany Massimo Imazio, MD, FESC Multimodality Cardiac Imaging Section, IRCCS Policlinico San Donato, Milan, Italy Jarosław D. Kasprzak, MD, PhD Professor of Medicine, Department and Chair of Cardiology, Bieganski Hospital, Medical University of Lodz, Lodz, Poland Rajdeep S. Khattar, DM, FRCP, FACC, FESC Consultant Cardiologist and Honorary Clinical Senior Lecturer, Royal Brompton and Harefield NHS Trust, and National Heart and Lung Institute, Imperial College, London, UK Lars Gunnar Klaeboe  Allan Klein, MD, FRCP(C), FACC, FAHA, FASE Professor of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, ​Director, Center for the Diagnosis and Treatment of Pericardial Diseases, Section of Cardiovascular Imaging, Department of Cardiovascular Medicine, Heart, Vascular, and Thoracic Institute, Cleveland Clinic, Cleveland, OH, USA Juhani Knuuti, MD, PhD, FESC Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland

Jonathan Leipsic, MD, FRCPC, MSCCT Physician, Department of Imaging and Cardiology, UBC, Vancouver, BC, Canada Riccardo Liga, MD, PhD Cardiologist, Cardiothoracic and Vascular Department, University Hospital of Pisa, Pisa, Italy Massimo Lombardi, MD, FESC, PhD Head, Multimodality Cardiac Imaging Section, I.R.C.C.S Policlinico San Donato, Milan, Italy Teresa López-​Fernández, MD Senior Consultant Cardiologist, Department of Cardiology, La PAz University Hospital, IdiPAZ Research Institue, Ciber CV, Madrid, Spain Joseph F. Maalouf, MD, FAHA, FACC, FASE Professor of Medicine, Director of Interventional Echocardiography, Consultant in Cardiovascular Diseases, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA Julien Magne, PhD Department of Cardiology, CHU de Limoges, Limoges, France Heiko Mahrholdt Professor Doctor, Head of Imaging, Department of Cardiology, Robert Bosch Medical Center, Stuttgart, BW, Germany Renzo Marcolongo, MD Senior Staff Physician, Department of Medicine, Azienda Ospedale Università Padova, Padova, Italy Pál Maurovich-​Horvat, MD  Priti Mehla, MD Lenox Hill Hospital, New York, NY, USA Luc Mertens, MD, PhD Professor of Paediatrics, Department of Cardiology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada Hector I. Michelena, MD, FACC, FASE, FESC Professor of Medicine, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA James Min, MD  Mark J. Monaghan, PhD, FRCP (Hon), FACC, FESC Director of Non-​Invasive Cardiology, King’s College Hospital, Denmark Hill, London, UK

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C ontribu tors Juan Manuel Monteagudo, MD Department of Cardiology, University Hospital Ramón y Cajal, Madrid, Spain Marie Moonen, MD, PhD University Hospital Sart Tilman, GIGA Cardiovascular Sciences, Department of Cardiology, Liege, Belgium Daniel Rodríguez Muñoz, MD, PhD Consultant, Department of Cardiology, Hospital Universitario 12 de Octubre, Madrid, Spain Denisa Muraru, MD, PhD, FESC, FACC, FASE Department of Medicine and Surgery, University of MilanoBicocca, Istituto Auxologico Italiano, IRCCS, Milan, Italy Eike Nagel, MD  Jagat Narula, MD, PhD, MACC Philip J. and Harriet L. Goodhart Chair of Medicine, Professor of Medicine, Radiology and Health System Design & Global Health, Chief, Division of Cardiology, Mount Sinai Hospital Morningside; Associate Dean for Global Health, Icahn School of Medicine at Mount Sinai, Executive Editor, Journal of the American College of Cardiology; Vice President Elect, World Heart Federation, New York, NY, USA Danilo Neglia, MD Fondazione Toscana G. Monasterio, Via G. Moruzzi, Pisa, Italy Stephan G. Nekolla, PhD, FESC Adjunct Teaching Professor, Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar der Technischen Universität München, and Deutsches Zentrum für Herz-​Kreislauf-​Forschung e.V. Partner site Munich Heart Alliance, München, Germany David E. Newby Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK Arnold C.T. Ng Princess Alexandra Hospital, Brisbane, Queensland, Australia; Faculty of Medicine, South Western Sydney Clinical School, the University of New South Wales, Australia Petros Nihoyannopoulos, MD  Robin Nijveldt, MD, PhD, FESC Cardiologist, Department of Cardiology, Radboud University Medical Center, Nijmegen, the Netherlands Louisa O’Neill King’s College London, UK; Guy’s and St Thomas NHS Foundation Trust, London, UK Mark O’Neill, MD  Stefan Orwat, MD Consultant Cardiologist, Adult Congenital and Valvular Heart Disease Department, University of Muenster, Muenster, Germany

Dudley J. Pennell, MD, FRCP, FACC, FESC, FRCR, FAHA, FMedSci, FSCMR National Heart and Lung Institute, Imperial College, Royal Brompton and Harefield NHS Foundation Trust, London, UK Pasquale Perrone-​Filardi Department of Clinical Medicine, Cardiovascular and Immunology Sciences, Federico II University, Naples, Italy Ferande Peters, MBBCH, FCP (SA), FACC, FESC, FRCP Senior Cardiologist, Associate Professor, Flora Hospital, Cardiovascular Pathophysiology and Genomics Unit, University of the Witwatersrand, Johannesburg, South Africa Philippe Pibarot, DVM, PhD, FESC, FACC, FAHA, FCCS Head of Cardiology Research, Department of Cardiology, Institut Universitaire de Cardiologie et de Pneumologie de Québec/​Québec Heart & Lung Institute, Laval University, Québec, QC, Canada Silvia Pica, MD Multimodality Cardiac Imaging Section, I.R.C.C:S., Policlinico San Donato, Milan, Italy Luc A. Pierard, MD, PhD, FESC Honorary Professor of Medicine, Department of Cardiology, University of Liège, Liège, Belgium Fausto J. Pinto, MD, PhD, FESC, FACC, FASE, FSCAI Head of Department, Department of Cardiovascular Medicine, University Hospital, Universidade de Lisboa, Lisbon, Portugal Sven Plein, MD, PhD, FRCP Professor, British Heart Foundation Professor of Cardiovascular Imaging, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK Francesca R. Pluchinotta, MD Consultant of Pediatric Cardiology and Adult Congenital Heart Disease, Multimodality Cardiac Imaging Unit, IRCCS Policlinico San Donato, Milan, Italy Gianluca Pontone, MD, PhD Director, Department of Cardiovascular Imaging, Centro Cardiologico Monzino, IRCCS, Milan, Italy Bogdan A. Popescu, MD, PhD, FESC, FACC Professor of Cardiology, University of Medicine and Pharmacy ‘Carol Davila’—​Euroecolab, Head of Cardiology Department, Emergency Institute for Cardiovascular Diseases ‘Prof. Dr. C. C. Iliescu’, Bucharest, Romania Sanjay Prasad, MD  Susanna Price, MD, PhD Professor of Cardiology and Intensive Care, Adult Intensive Care Unit, Royal Brompton Hospital, London, UK Kuberan Pushparajah, MD 

C on t ri bu tor s Ronak Rajani, BM, DM, FRCP, FESC, FSCCT, FACC Department of Cardiology, Guy’s and St Thomas’ NHS Foundation Trust, London, UK Reza Razavi, MD  Ornella Rimoldi, MD IBFM, Consiglio Nazionale delle Ricerche, Segrate, Italy Jose F. Rodriguez-​Palomares, MD, PhD Director of Cardiovascular Imaging Department, Department of Cardiology, Vall Hebrón Hospital, Barcelona, Catalonia, Spain Lawrence Rudski, MD, FRCPC Director, Azrieli Heart Center, Jewish General Hospital, McGill University, Montreal, QC, Canada Elif Leyla Sade, MD Professor of Cardiology, Department of Cardiology, Baskent University, Ankara, Turkey Ciro Santoro, MD Department of Advanced Biomedical Science, Federico II, University Hospital, Naples, Italy Antti Saraste, MD, PhD, FESC Professor, Chief Cardiologist, Heart Center, Turku University Hospital, Turku, Finland Muhamed Saric, MD, PhD Director, Noninvasive Cardiology, Professor of Medicine, Leon H. Charney Division of Cardiology, New York University Langone Health, New York, NY Aldo L. Schenone, MD Chief Cardiovascular Imaging Fellow Section of Non Invasive Cardiovascular Imaging, Department of Radiology Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Juerg Schwitter, MD Full Professor, Cardiovascular Department, University Hospital Lausanne, CHUV, Faculty of Biology and Medicine, Lausanne University, Lausanne, VD, Switzerland

Robert J. Siegel, MD, FACC Kennamer Chair in Cardiac Ultrasound, Medical Director, Clinic for Hypertrophic Cardiomyopathy and Aortopathies; Director, Cardiac Noninvasive Laboratory; Professor of Medicine, Cedars-​Sinai Medical Center and UCLA School of Medicine, CA, USA Iain Sim, MD Clinical Research Fellow in Cardiology, King’s College London, UK Marta Sitges, MD, PhD Director, Cardiovascular Institute, Hospital Clinic, Professor of Medicine, University of Barcelona, Barcelona, Spain Lindsay A. Smith University Hospital Southampton, Southampton, UK James Stirrup, DLM, MD(Res), FSCCT, FRCP Consultant Cardiologist, Department of Cardiology, Royal Berkshire NHS Foundation Trust, London, UK Stephan Stobe, MD  Rolf Symons, MD, PhD Department of Imaging and Pathology, Faculty of Medicine, University Hospitals Leuven, KU Leuven, Leuven, Belgium Ewa Szymczyk, MD  Bhupendar Tayal, MD  Upasana Tayal, MD  Gisela Teixidó-​Turà, MD, PhD, FESC Vall d’Hebron Research Institute, Hospital Universitari Vall d’Hebron, CIBER-​CV, Barcelona, Spain Alexandra Toste, MD Hospital da Luz, Inherited Cardiovascular Diseases & Hypertrophic Cardiomyopathy Center, Affiliated Professor at NOVA Medical School, Lisbon, Portugal Richard Underwood, MA, DM, FRCP, FRCR Emeritus Professor of Cardiac Imaging, National Heart and Lung Institute, Imperial College London, London, UK

Udo Sechtem, MD Associate Professor of Cardiology, Cardiologicum and Robert-​ Bosch-​Krankenhaus, Stuttgart, Germany

Philippe Unger, MD, PhD Head of Department, Department of Cardiology, CHU Saint-​ Pierre, Université Libre de Bruxelles, Brussels, Belgium

Joseph B. Selvanayagam, MD, PhD Professor in Cardiovascular Medicine, Flinders University, Adelaide, Australia

Albert C. van Rossum, MD, PhD Department of Cardiology, Amsterdam University Medical Centers, Amsterdam, the Netherlands

Roxy Senior, MD, DM, FRCP, FACC, FESC Consultant Cardiologist and Professor of Cardiology, Department of Cardiology, Royal Brompton Hospital, London, UK

Jens-​Uwe Voigt, MD, PhD, FESC Head of Echocardiography, Department of Cardiovascular Diseases, University Hospitals Leuven, Leuven, Belgium

Rosa Sicari, MD, PhD Research Director, Department of Biomedicine, Institute of Clinical Physiology, Pisa, PI, Italy

John Whitaker Division of Imaging Sciences and Biomedical Engineering, King’s College, London, UK

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C ontribu tors Steven Williams Division of Imaging Sciences and Biomedical Engineering, King’s College, London, UK

Kyriakos Yiangou, MD, MSc, FESC, FACC, FEACVI Cardiologist, President Cyprus Society of Cardiology

Jeremy Wright, MBBS, FRACP Cardiologist, Greenslopes Private Hospital, Brisbane, Australia

Ali Yilmaz, MD Department of Cardiology, Division of Cardiovascular Imaging, University Hospital Münster, Germany 

Nina C. Wunderlich, MD Head of Noninvasive Cardiology, Department of Cardiology, Cardiovascular Center Darmstadt, Darmstadt, Hessen, Germany

José Luis Zamorano, MD, PhD Head of Cardiology, University Hospital Ramon y Canal, Madrid, Spain

SECTION 1

Technical aspects of imaging 1 Conventional echocardiography—​basic principles 

3

Andreas Hagendorff, Stephan Stobe, and Bhupendar Tayal

2 Nuclear cardiology (PET and SPECT)—​basic principles 

41

Danilo Neglia, Riccardo Liga, Stephan G. Nekolla, Frank M. Bengel, Ornella Rimoldi, and Paolo G. Camici

3 Cardiac CT—​basic principles 

57

Gianluca Pontone and Filippo Cademartiri

4 CMR—​basic principles 

67

Jan Bogaert, Rolf Symons, and Jeremy Wright

5 Training and competence in cardiovascular imaging  Kevin Fox and Marcelo F. Di Carli

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Conventional echocardiography—​basic principles Andreas Hagendorff, Stephan Stobe, and Bhupendar Tayal Contents Introduction  3 Principles of transthoracic echocardiography—​practical aspects  3 Principles of image optimization and identification of artefacts—​practical aspects  7 Standardized data acquisition in transthoracic echocardiography  7 Principles of transoesophageal echocardiography—​practical aspects  24 Standardized data acquisition in transoesophageal echocardiography  28 Standard values in transthoracic and transoesophageal echocardiography  37

M-​mode measurements  37 Two-​dimensional measurements  38 Pulsed spectral Doppler measurements  38 Continuous wave Doppler measurements  38 Pulsed spectral tissue Doppler measurements  38

Acknowledgements  40

Introduction Echocardiography is an imaging technique that enables accurate assessment of cardiac structures and cardiac function. Conventional echocardiography involves different modalities—​especially the M-​mode, the 2D, and colour Doppler, as well as the pulsed-​ wave and continuous wave Doppler. The M-​mode illustrates the reflections of a single sound beam plotted against time. 2D echocardiography enables the documentation of views, which represent characteristic sectional planes of the moving heart during one heart cycle. Colour Doppler echocardiography adds the information of blood flow to the 2D cineloop. Pulsed-​wave Doppler is the acquisition of a local blood flow spectrum of a defined region represented by the dimension of the sample volume, whereas continuous wave Doppler displays the blood flow spectrum of all measured blood flow velocities along a straight line sound beam from its beginning to the end. The handling of the transducer has to be target-​oriented, stable with respect to the imaging targets, and coordinated with respect to angle differences between the defined views to use all these modalities correctly to get optimal image quality of the cineloops and spectra. Thus, the focus of this chapter will be a mainly practically oriented description of scanning technique in transthoracic and transoesophageal echocardiography. The echocardiographic documentation requires image optimization and ultrasound machines, which fulfil the international laboratory standards in echocardiography. Thus, the equipment has to be minimally capable to enable broadband 2D imaging, M-​mode imaging, pulsed and continuous wave Doppler, as well as colour-​coded imaging, pulsed tissue Doppler imaging, and complete digital storage capability. In addition, the ultrasound system has to have all technical possibilities for transoesophageal, contrast, and stress echocardiography. An electrocardiographic (ECG) recording should generally be performed in order to be able to capture complete heart cycles according to the ECG trigger. This chapter is written in accordance with the current international guidelines and recommendations [1–​7].

Principles of transthoracic echocardiography—​ practical aspects The main principle of echocardiographic scanning is an exact or best possible manual control of the region of interest during the technical procedure. This principle includes the ability to move a certain cardiac structure within the scan sector from the left to the right and vice versa without losing the cardiac structures of the selected sectional

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plane. In addition, this aspect is documented by the ability to rotate the transducer exactly about 60 or 90° without losing the defined cardiac structure in the centre of the primary scan sector before rotating. In other words, the visualization of cardiac structures in the centre of the scan sector has to be combined with the technical skill of the investigator to change only one plane within the spatial coordinates to achieve accurate characterization and documentation of the target cardiac structure. Thus, the easy message of transthoracic echocardiography is scanning by tilting without flipping and rotating, by flipping without tilting and rotating, as well as by rotating without tilting and flipping. This sounds easy, but it requires a stable transducer position next to the skin of the patient, an absolutely stable guiding of the transducer, and a stereotactic manual control of the transducer. Regarding these aspects it is surprising that the finger position of holding a transducer has almost never been described in lectures and books about echocardiography, whereas in every book about musical instruments instructions of hand and finger positions, and illustrations of fingering charts are given. In transthoracic echocardiography there is a complex interaction between the eyes, the brain, and the hand muscles to coordinate looking to a monitor to detect incongruities between the actual view and defined views and to correct them by manual manoeuvres to get the standardized views. Thus, it is like ‘seeing’ the heart with your hands. A basic position of the transducer in the hand is necessary to get the orientation for the scan procedure for an easy, but controlled change of a sectional plane. This implies that a defined holding of the transducer is always linked to a

defined hand position which has to be linked with a defined view. In echocardiography in adult patients, the echocardiographic investigation normally starts with the left parasternal approach. It is obvious that the basic holding of the transducer should be linked to the long-​axis view of the left ventricle. In consequence, all possible long-​axis views that can be acquired between the position of the left parasternal and the apical approach should be linked to this defined hand-​holding of the transducer. If you change your basic position of holding the transducer during the scanning procedure of the same sectional plane, the imagination and association of the individual coordinates of the heart within the thorax will be lost by the investigator, which means that he will become disoriented or blind during scanning. It has to be mentioned and emphasized, that scanning is possible with the right as well as with the left hand. The argument for a correct scanning technique is always the acquisition of standardized images with high image quality. Thus, echocardiographic scanning can be performed as the investigator is, or has been, taught how to do it. The author of this chapter, however, scans with the right hand. Thus, the images of how to hold the transducer and adjust the finger positions are shown for right-​hand scanners. To get a stable position for the transducer holding, all fingers are generally lifted and not extended. The pulps of the fourth and fifth fingers conveniently lie on the small edge of the transducer without any muscle tension (E Fig. 1.1a). The pulp of the thumb is con­veniently placed on the notch of the transducer without any muscle tension (E Fig. 1.1b). This convenient relaxed transducer holding has to be conceptionally combined with

Fig. 1.1  Correct relaxed holding of the transducer using the right hand. The transducer lies on the fourth and fifth finger without any muscle tension (a), the pulp of the thumb only has contact to the notch of the transducer (b). The pulps of the fourth and fifth finger have contact to the skin (c) and the feeling of this transducer holding is combined with the parasternal log axis view (d).

Principles of t r a n sthor aci c echo ca rdi o g r a phy — pr acti c a l aspe c ts

Fig. 1.2  Examples of inconveniently holding the transducer. In (a) the fourth and fifth finger are between the transducer and the skin like writing with a

pencil. No stable contact to the skin results in non-​stabilization of the transducer. In (b) the holding is like encompassing a horizontal bar. Thus, rotation of the transducer is not performed by the hand—​it has to be done by the shoulder and/​or cubital joint. In (c) the thumb is too extended and the pulp of the thumb is not at the notch causing a blind feeling when moving or rotating the transducer. In addition, the mistake in Fig. 1.2a is also seen. In (d) no finger has contact to the skin. Thus, every trembling of the hand is bridged to the transducer and consequently to the images on the monitor. It is also not possible to get a basis for a defined flipping, tilting, and rotation, because the starting position is not stable.

the basic position of the transducer in the parasternal long-​axis view of the heart (E Fig. 1.1c, d). The loss of the feeling for the notch and extended or tensed fingers in the starting position will induce discomfort and restrict the degrees of freedom for the movement of the transducer. Thus, wrong transducer holdings (E Fig. 1.2a–​d) will lead to disorientation and difficulties in fine-​tuning for adjusting correct standardized views. An often observed mistake is not to fix the fourth and fifth finger on the skin of the patient, leading to an unstable transducer position. With tilting over the small edge using the transducer holding of this starting position in the long-​axis view, the mitral valve, for example, can be moved from the right to the left and vice versa without losing the long-​axis view. A clockwise rotation of the transducer from the starting position is easy (E Fig. 1.3a), because there is free space to turn the thumb clockwise by bending backwards the fourth and fifth fingers (E Fig. 1.3b, c). A 90° rotation is easily possible and thus, you will get the feeling of rotating exactly 90° clockwise at the left parasternal window to visualize a correct short-​axis view (E Fig. 1.3d). After acquisition of the necessary parasternal short-​axis views the transducer is rotated counterclockwise back to the correct long-​axis view. The correct position of the apical window and the correct apical long-​axis view can be achieved by sliding down from the parasternal window to the apex without losing

the sectional plane of the long-​axis view (E Fig. 1.4). At the end of this movement the right hand can support itself against the thorax with the complete auricular finger (E Figs. 1.5a, b). Fingers placed between the transducer and the thorax in this position will disturb or inhibit the correct documentation of apical standard views by positioning the transducer too perpendicular to the body surface inducing a right twisted position of the heart within the scan sector and/​or foreshortening views. Without tilting and flipping the correct apical long-​axis view, a clockwise rotation of exactly 60° can be performed (E Fig. 1.5c) to visualize a correct 2-​chamber view (E Fig. 1.5d). Combining a defined transducer holding always with the long-​ axis view and getting the stable feeling for this combination are the prerequisites for target-​controlled scanning and the accurate assessment of cardiac structures. It is obvious that minimal manipulations of the transducer position can be easily performed and stably fixed using the correct scanning technique. Thus, a correct scanning technique is the prerequisite for images with at least best possible image quality. The aim of a sufficient transthoracic, and also transoesophageal, echocardiographic investigation should be an almost reproducible standardized documentation, which enables an accurate diagnostic analysis for correct decision-​making. A standardization of the documentation enables a comparison between current and previous findings to detect changes, improvements, or

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Fig. 1.3  Starting with the correct holding of the transducer for displaying the parasternal long-​axis view (a) the transducer is exactly rotated 90° clockwise (b),

after this movement the pulp of the thumb is at the broad side of the transducer at the top and the third finger is at the broad side of the transducer at the bottom (b), while the fourth and fifth finger are retracted (c), but they have still contact to the skin. This holding is linked with all parasternal short-​axis views (d).

Fig. 1.4  Photo composition of the transducer holding for the different long-​axis views between the standardized parasternal approach and the standardized

apical approach. On the left side the different holdings at the correct parasternal position, at a position between the parasternal and apical position, as well as at the correct apical position are shown. In the centre the photomontage of all transducer holdings is shown documenting the plane of all long-​axis views. On the right side the corresponding views are shown.

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.5  With the transducer holding of the parasternal long-​axis view

the hand is slid down to the apical long-​axis view (a). At the position of the apical long-​axis view the fourth and fifth finger still remain on the skin. In addition, the complete ulnar area of the fifth finger is placed in position against the thorax for scanning from the apical approach (a). This transducer holding is linked with the apical long-​axis view (b). A clockwise rotation of 60° without tilting and flipping has to be done (c) to get the correct apical 2-​chamber view (d).

deterioration of the cardiac state in follow-​ups. Furthermore, the more standardization is present, the more intra-​and interobserver variability is reduced. The basis for the correct configuration of an echocardiographic data acquisition and examination—​including data acquisition, data documentation, data storage, interpretation, and reporting of the results—​as well as the correct measurements and calculations of numerical values in echocardiography is provided by already published national and international guidelines and position papers.

which interacts with the tissue. The mapping of cardiac structures depends on the reflection of the ultrasound waves due to the travel time between transducer and the respective reflexion zone and its way back as well as the intensity of reflection. However, reflection is only one interaction with the tissue. Refraction, dispersion, and attenuation are also contributors to the image quality of the reconstructed cardiac structures. Thus, acoustic impedances and the orientation of boundaries in relation to the ultrasound beams between two different tissues have major impacts on the receiving ultrasound signals at the transducer for the final image reconstruction. With respect to the acoustic window in each patient the imaging settings have to be altered and optimized to illustrate the respective cardiac structures in an adequate fashion. The most important issue to get an optimal image quality is the correct positioning of the transducer. The most important technical factors influencing echocardiographic parameters are listed in E Table 1.1. Artefacts in echocardiography are created by the interactions of ultrasound waves with the tissue and by the image reconstruction algorithms due to beam formation properties. Despite the visualization of artefacts being compatible with the physical laws of reflection and refraction, artefacts are not consistent with the usual assumptions of ultrasound imaging. The common assumptions of ultrasound imaging are (1) ultrasound travel time is related to a specific speed (1540m/​s), (2) ultrasound waves are attenuated uniformly, (3) acoustic reflection of ultrasound waves occurs just once at a reflector after transmission and (4) the ultrasound transmission is formed by a main thin beam. Artefacts will be created mainly in the presence of strong reflectors causing multiple reflections between the reflectors. Artefacts have to be recognized to avoid misinterpretations. Sometimes artefacts can be avoided or minimized by changing the ultrasound settings or by changing the scanning modalities (E Fig. 1.8a–​c, Fig. 1.9a–​f, Fig. 1.10a–​d, Fig. 1.11a–​d, Fig. 1.12a–​d). The common artefacts observed in 2D-​, spectral, and colour Doppler echocardiography are listed and described in E Table 1.2.

Principles of image optimization and identification of artefacts—​practical aspects

Standardized data acquisition in transthoracic echocardiography

The echocardiographic images of all modalities are reconstructed by modern techniques using the physical properties of the ultrasound waves interacting with the cardiac and thoracic tissue. Thus, basic knowledge about the physics of ultrasound is necessary to understand the image reconstruction—​especially with respect to the possibilities of imaging optimization and the identification or detection of artefacts. Ultrasound waves (E Fig. 1.6a–​f ) (E Fig. 1.7a–​d) in echocardiography are generated by voltage-​induced vibrations of piezoelectric crystals of the transducers forming an ultrasound beam

Left parasternal and apical scanning should normally be performed in left lateral position of the patient. The transthoracic echocardiographic examination should start with the correct documentation of the conventional two-​ dimensional left parasternal long-​axis view of the left ventricle (E Fig. 1.13a–​b). This sectional plane is characterized by the centre of the mitral valve, the centre of the aortic valve, as well as by the ‘imaginary’ cardiac apex, which cannot be visualized from the parasternal approach due to the superposition of the left lung. The following anatomical structures are visualized by

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Fig. 1.6  Impact of ultrasound frequency on 2D-​echocardiography: parasternal long-​a xis view in the same patient using low (a) and high (b)

frequencies—​transoesophageal long-​axis view in the same patient using low (c) and high (d) frequencies (better spatial resolution with higher frequencies, but less penetration). Impact of ultrasound frequency on Doppler echocardiography: transmittal pulsed-​wave Doppler spectrum with low (e) and high (f) frequencies (sharper contours with higher frequencies, but less penetration). Impact of gain and low velocity reject on Doppler echocardiography: transaortic continuous wave Doppler spectrum with low (e) and high (f) gain and adjusted low velocity reject (f) (better contour detection of the velocity spectrum after adjustment)

the parasternal long-​axis view. In the nearfield of the transducer, the first myocardial structure is the free right ventricular wall—​ normally parts of the right ventricular outflow tract. The left ventricular cavity in the longitudinal section is surrounded by the midbasal anteroseptal and posterior regions of the left ventricle. The mitral valve is sliced in the centre of the valve plane nearly perpendicularly to the commissure. The aortic valve is also sliced in the centre of the valve in longitudinal direction. The aortic root and the proximal part of the ascending aorta are longitudinally intersected. Behind the aortic root the left atrium is longitudinally intersected. The posterior left ventricular wall is bordered by the posterior epicardium and the diaphragm. The far field of the parasternal long-​axis view should include the cross-​section of the descending aorta behind the left atrium. A standardized left parasternal long-​axis view can be verified by the following display of the heart within the sector. The mitral valve has to be centred in the scanning sector. Then, the ventral boundary of the mid-​ anteroseptal region of the left ventricle on the left side has to be

in line with the ventral boundary of the ascending aorta on the right side of the sector. Furthermore, the check of the correct longitudinal parasternal long-​axis view should include the ascending aorta visualized as a tube and not as an oblique section, the central valve separation of the mitral and aortic valves, as well as the missing of papillary muscles. If papillary muscles are sliced, the sectional plane is not in the centre of the left cavity, which corresponds to a non-​standardized view. For qualitative assessment of flow phenomena at the mitral and aortic valves, as well as for the detection of perimembranous ventricular septal defects, a colour-​ coded 2D cineloop of the left parasternal long-​axis view can be added to the documentation (E Fig. 1.13c–​d). With respect to the documentation of the right heart, tilting the transducer to the sternal regions enables the visualization of the right ventricular inflow tract with a longitudinal sectional plane through the tricuspid valve (E Fig. 1.14a–​b). Tilting the long-​ axis view to the lateral regions of the heart enables the visualization of the right ventricular outflow tract with the longitudinal

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.7  Impact of ultrasound frequency on colour Doppler echocardiography: apical long-​axis view in a patient with mitral regurgitation using adjusted (a) and too high (b) Doppler frequency (jet area is not visualized with too high frequencies due to loss of penetration). Impact of colour pixel size on colour Doppler echocardiography: parasternal long-​axis view in a patient with aortic regurgitation using adjusted (c) and smoothed (b) Doppler settings (jet area and vena contracta are enlarged with wrong ultrasound settings—​right image).

Table 1.1  Targets for imaging optimization in echocardiography Imaging Target: physical background and explanation for image reconstruction

Button of the ultrasound machine and its alterations

Potential important effects of diagnosis

Optimization of the image quality and potential adverse effects

2D-​axial spatial resolution—​axial resolution in the direction of the alignment of the ultrasound beam is very good (M-​Mode). Spatial resolution is related to ultrasound frequency and the bandwidth of the transducer.

Ultrasound frequency—​the higher the ultrasound frequency the better the spatial resolution. The bandwidth of the transducer cannot be changed.

With poor spatial resolution delineation of reflections are suboptimal. Thus, distances and areas will be measured too small than they normally can be visualized.

Use higher ultrasound frequencies to get sharper images. However, loss of ultrasound penetration is related to the increasing ultrasound frequencies.

2D-​axial lateral resolution—​lateral resolution is less than axial resolution and depends on the density of ultrasound beams (and secondary to ultrasound frequency).

Angle size—​the smaller the angle the better the lateral spatial resolution.

With poor lateral resolution distances between reflection boundaries will be measured too small (e.g. left ventricular outflow tract), reflection zones itself will be measured too broad (e.g. coaptation length of the aortic valve in a parasternal long-​axis view).

Measurements of cardiac structures should be measured preferably in axial direction. If measurements in lateral orientation have to be performed, the smallest angle should be used.

2D-​Contrast—​contrast will be influenced by penetration and by the grey-​scale range.

Ultrasound frequency—​The better penetration (e.g. by decreasing ultrasound frequency) the better the contrast. Compression—​the lower the compression (= less grey levels in a predefined range) the better the contrast.

Increasing contrast enhances the risk of non-​detection of structures with low echogenicity, e.g. abscess formation in patients with endocarditis or recently originated thrombus formations.

Depending on the excellence of the acoustic window the 2D grey levels have to be adjusted carefully with respect to the potential diagnosis. In cases of doubt higher compression in the presence of sufficient penetration is better. (continued)

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Table 1.1  Continued Imaging Target: physical background and explanation for image reconstruction

Button of the ultrasound machine and its alterations

Potential important effects of diagnosis

Optimization of the image quality and potential adverse effects

2D-​Brightness—​brightness of the ultrasound image is influenced by the brightness of the surrounding. The more light in the surroundings, the more brightness is necessary to detect cardiac structures.

2D gain—​the higher the gain, the brighter With increasing gain distances and thicker the reflection patterns of the and areas will be measured too ultrasound image. small than they normally can be visualized. With decreasing gain structures cannot be detected in bright surroundings.

In dark rooms, e.g. a typical ultrasound laboratory, normally lower gain settings should be used than in bright rooms, e.g. in the theatre or emergency department.

Sharpness of the pw-​and cw Doppler spectrum—​the sharpness of the Doppler spectrum is influenced by multiple ultrasound settings.

Doppler frequency—​the higher the Doppler frequency, the better the sharpness of the spectrum. Scale—​the better the adjustment of the signal amplitude to the scale, the better the resolution of the spectrum. Low velocity reject—​the higher low velocity reject, the less tissue Doppler signals. It has to be adjusted with alterations of the scale. Sample volume—​The larger the sample volume, the brighter the pw Doppler signal and the lower the sharpness. Doppler gain—​the higher the Doppler gain, the brighter the spectrum. Doppler compression—​the lower the compression, the brighter the spectrum.

With increasing Doppler frequencies penetration will be reduced. Thus, depending on the acoustic properties and by using inadequate adjustment of scale, low velocity reject and gain, signals can be lost out of the detection range. With decreasing compression maximum velocities in pw Doppler spectra will not be visualized, if the alignment of the ultrasound beam is not exactly in the regions of the central blood flow with the highest velocities.

In general, Doppler spectra have to be adjusted with an optimal alignment to the central blood stream. In cases of doubt avoid ranges of lower compression and adjust Doppler frequencies and sample volume (if pw Doppler is used) with respect to the penetration of the ultrasound.

Brightness of colour-​coded Doppler signal in relation to the grey-​scale image—​the more brightness of colour, the more overlay of the tissue by the colour.

Colour Doppler gain—​the higher the colour Doppler gain, the higher the intensity of the colour and the more overlay of tissue by the colour is present.

With increasing colour Doppler gain distances and areas will be measured too large than they normally can be visualized (e.g. especially jet flow areas). Blood flow jet formations of turbulences will be better visualized perpendicular to the ultrasound beam due to the better axial resolution in comparison to the lateral resolution (e.g. vena contracta of a mitral regurgitation in the parasternal long-​axis view).

Colour Doppler gain has to be adjusted at clear boundaries to tissue. Normally adjustment should be performed in the left ventricular outflow tract. Overlapping of colour and tissue should be minimized to a distance of about 1 mm with respect to the penetration and quality of the acoustic window.

Blood flow velocities of the colour-​ coded Doppler signal—​the lower the blood flow velocities, the darker the colour-​coded Doppler signal.

Colour Doppler Scale—​low blood flow velocities will be better visualized with decreasing colour Doppler scale.

With decreasing colour Doppler scale low flow regions will be better elucidated with colour. Thus, flow areas in cardiac cavities will be depicted larger than using higher Doppler scales (e.g. especially jet flow areas).

Colour Doppler scale has to be adjusted to the flow phenomenon which has to be analysed. Thus, if venous flow should be visualized, normally lower colour Doppler scales will be used than in the presence of high flow conditions.

If the sharpness of the colour-​coded Doppler signal is not optimized, all important semi-​quantitative parameters of grading valvular heart diseases, e.g. vena contracta, proximal convergence areas, regurgitant orifice areas will be determined too large.

The sharpness of the colour-​ coded Doppler signal has to be adjusted to the flow phenomenon which has to be analysed. The most challenging problem is the loss of colour penetration by the attempts to improve the signal quality. Thus, in cases of doubt avoid ranges no smoothing algorithms should be used and an adequate colour signal has to be visualized in the region of interest when colour Doppler frequency is increased.

Sharpness of the colour-​coded Doppler Colour Doppler ultrasound frequency—​ signal in relation to the grey-​scale the higher the colour Doppler image—​the sharpness of the colour frequency, the better the elucidation Doppler signal is influenced by multiple and sharpness of the colour signal, but ultrasound settings. the less penetration of the colour signal. Colour low velocity reject—​the higher low velocity reject, the brighter the colour signal. Smoothing algorithm of the colour signals—​the colour pixels can be smoothed with respect to radial and lateral resolution. The more smoothing, the brighter the pixels.

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.8  Impact of colour pixel size on colour Doppler

echocardiography: apical long-​axis view in a patient with mitral regurgitation using adjusted (c) and smoothed (b) Doppler settings (jet area and vena contracta is enlarged with wrong ultrasound settings—​right image). Impact on 2D-​gain on Doppler echocardiography: apical long-​axis view in a patient with mitral regurgitation using adjusted (a) and too high (b) 2D-​ gain (jet area and vena contracta are not visualized with too high 2D-​gain settings).

sectional plane through the pulmonary valve (E Fig. 1.14c–​d). These views should also be documented using colour-​coded 2D cineloops (E Fig. 1.14e–​h). The 90° clockwise rotation of the transducer from the transducer position of the correctly set parasternal long-​axis view will lead to sectional short-​axis views of the heart. The correct transducer position to display standardized parasternal short-​ axis views using conventional transthoracic echocardiography is documented by a M-​mode sweep (E Fig. 1.15a). Parasternal short-​axis views should be documented with respect to an accurate definition of the plane according to cardiac structures, which enables a high reproducibility of each view. Short-​axis views are defined by the accurate cross-​section through the left ventricular attachment of the papillary muscles (E Fig. 1.15b), through the papillary muscles (E Fig. 1.15c), through the chord heads, as well as the chord strands (E Fig. 1.15d), through the mitral valve (E Fig. 1.15e), through the interatrial septum and the left ventricular outflow tract (E Fig. 1.15f), through the aortic valve (E Fig. 1.15g), the aortic root and the proximal ascending aorta (E Fig. 1.15h), as well as by a nearly longitudinal plane through the pulmonary trunk and the bifurcation of the pulmonary arteries (E Fig. 1.15i). The acquisition of a correct M-​mode sweep is performed within 6–​12 cardiac cycles using the cursor in the centre line of all parasternal short-​axis

views by scanning through the left ventricle over the long axis of the left ventricle by tilting the transducer starting from the short-​axis view between the papillary muscles up to the cranial short-​axis view of the centrally intersected aortic valve and ascending aorta (E Fig. 1.15a). By deriving M-​modes and M-​ mode sweeps in the short axis, it can always be checked whether the left heart is sliced exactly in its centre line or only a secant view of the left ventricle is documented. This fact favours the acquisition of M-​modes using short-​axis views instead of a long-​ axis view. The correct transducer position is documented in the M-​mode sweep by a horizontal line between the border of the ventral septum and the border of the ventral ascending aorta. The alternative to document the correct transducer position in the long-​axis view simultaneously to the short-​axis views is only possible by biplane scanning. The problem of isolated short-​axis views is the fact that the transducer position is too much lateral or caudal, which causes an oval conformation of the ventricular wall at the level of the left ventricle. The consequence for measurements of left ventricular dimensions and wall thicknesses is that the left ventricular cavity is measured too large and the ventricular wall is measured too thick (E Fig. 1.16). For training aspects and to document manual skills of target-​ oriented scanning, the correct acquisition of the M-​mode sweep should be integrated into the educational process like a driver’s

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(a)

(b)

(c)

(d)

(e)

(f)

Fig. 1.9  Impact of the Nyquist limit (scale) on colour

Doppler echocardiography: apical long-​axis view in a patient with mitral regurgitation with different colour scales—​ maximum velocity of 11 cm/​s presents all flow signals above the Nyquist limit (a), maximum velocity of 44 cm/​s presents adequate blue flow signals in the ventricle during systole, but overall turbulences in the left atrium (b) and maximum velocity of 66 cm/​s presents flow signals of the regurgitation adequately to the velocities of the jet (c). Impact of the Nyquist limit (scale) on the proximal convergence areas in colour Doppler echocardiography: zooming of an apical long-​axis view in a patient with mitral regurgitation with different colour scales—​with increasing scale from 37 cm/​s (d) to 48 cm/​s (e) and 58 cm/​s (f) the radius of the proximal convergence zone becomes smaller.

licence for echocardiography. For clinical practice the correct M-​ mode sweep represents a characteristic profile of the individual human heart. According to European recommendations, however, it is not mandatory to acquire the M-​mode sweep. The standard documentation includes only parasternal short-​ axis views at the mid-​papillary level, at the mitral valve level and at the aortic level. In all parasternal short-​axis views the centre of the left ventricle or the aortic valve should be in the middle of the scanning sector. Near the transducer the parasternal short-​axis view at the mid-​papillary level (E Fig. 1.17a–​d) shows the free right ventricular wall, the right ventricular cavity, all mid-​segments of the left ventricular wall (near the transducer: anteroseptal—​0°; then clockwise: anterior—​ 60°; lateral—​ 120°; posterior—​ 180°; inferior—​240°; inferoseptal—​300°), the left ventricular cavity, the anterolateral transversal mid-​papillary muscle between 60° and 90° at the inner wall of the left ventricle and the posteromedial transversal mid-​papillary muscle between 210° and 240° at the inner wall of the left ventricle. The parasternal short-​axis view at the mitral valve level (E Fig. 1.18a–​d) shows the free wall of the right ventricular outflow tract, the cavity of the right ventricular outflow tract, all basal segments of the left ventricular wall and the left ventricular cavity, near the transducer in the left

ventricular cavity the anterior mitral leaflet, which is anatomically one leaflet but can be described by three portions (the A1-​ scallop near the anterolateral left ventricular wall, the A2-​scallop in the centre of the anterior mitral leaflet, the A3-​scallops near the posteromedial left ventricular wall) and far from the transducer in the left ventricular cavity the posterior mitral leaflet, which is divided anatomically into three scallops (the P1-​scallop near the anterolateral left ventricular wall, the P2-​scallop in the centre of the posterior mitral leaflet, the P3-​scallops near the posteromedial left ventricular wall). The parasternal short-​axis view at the aortic valve level (E  Fig. 1.19a–​d) is characterized by the following cardiac structures. The basal free wall of the right ventricular outflow tract is near the transducer. The right ventricular cavity is bounded on the left side of the sector by the tricuspid valve and on the right side by the pulmonary valve. The aortic valve is in the centre of the sector behind the right ventricle. During diastole the right coronary cusp is ventrally located, the left coronary cusp is between 60° and 180°, and the non-​coronary cusp is between 180° and 300°. Close to the commissure between the right and the left coronary cusp at the aortic valve annulus, the dorsal cusp of the longitudinally intersected pulmonary valve is located. Close to the commissure between the right and the non-​coronary cusp at the aortic valve annulus, the septal leaflet of the tricuspid

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.10  Parasternal short-​axis view (a) and a corresponding M-​Mode (b) with increased depth to document reverberation artefacts due to strong reflectors.

The epicardium represents one strong reflector (thick red arrow) causing a reverberation signal in the far field (thin red arrow) as well as comet tail artefacts (yellow arrows). In addition the mirroring of the posterior wall is shown (green lines). In the M-​Mode the parallel movement of the artefact in relation to the reflector is labelled by the red arrows. The biplane parasternal view with the short axis characterized by the white line in the parasternal view documents again the strong reflector (red arrow), comet tail artefacts (yellow arrows) and mirror artefacts (green lines). In addition the reverberations of the mitral valve are seen in the long axis as well as in the short-​axis view (blue arrows). It has to be mentioned that the mitral valve as the reflector is not visualized in the short-​axis view (c). A reverberation artefact mimicking a dissection membrane in the ascending aorta is shown in (d).

valve is located. At the far side of the aortic valve, the left atrium is shown. Close to the aortic valve annulus, near to the non-​ coronary cusp, the perpendicular intersected interatrial septum is located. Between the aortic valve and the left atrium, the fibrotic aorticomitral junction is located. Between the interatrial septum and the tricuspid valve is the right atrium. It has to be mentioned that all parasternal short-​axis views display the cardiac structures mirror-​inverted. The colour-​coded short-​axis views through the mitral and aortic valve are additionally suitable for qualitative analysis of the location of mitral valve regurgitation and semi-​quantification of aortic valve regurgitation by analysing the regurgitant orifice during diastole. From the parasternal approach, colour-​coded and pulsed spectral Doppler imaging of the right ventricular outflow tract or the pulmonary valve should be generally added to a standard documentation in order to calculate the cardiac output of the

right heart and to estimate the pulmonary pressure by acceleration time and the morphology of the flow profile, retrospectively (E Fig. 1.20a–​e). If pulmonary regurgitation is present, and right heart or pulmonary diseases are suspected, a continuous wave Doppler spectrum through the pulmonary valve should be documented to estimate end-​diastolic and mean pulmonary pressure by the end-​diastolic and maximal velocities of the regurgitant flow. The locating of the transducer directly at the cardiac apex is essential for the documentation of the correct apical sectional planes. This is possible by guiding the transducer to the correct apical position by sliding in caudolateral direction on the skin of the patient from the correct transducer position of a standardized parasternal long-​axis view to the correct transducer position of a standardized apical long-​axis view (E Fig. 1.21). The apical long-​ axis view is characterized by the same cardiac structures as the parasternal long-​axis view (E Fig. 1.21). The standardized apical

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Fig. 1.11  Transoesophageal simultaneous 2D-​

and colour-​coded Doppler short-​axis views of the descending aorta. The distal aortic wall represents a strong reflector (red arrow). Comet tail artefacts are labelled by yellow arrows. The mirror artefact of the colour flow (green line) is shown by the different colour signal in red inside the aorta and in blue inside the artefact of the aortic cavity. Near field clutter in a transoesophageal 2D-​short-​axis view of the descending aorta is presented in (b). Mirror artefacts of the aortic valve within the right ventricular outflow tract (green lines) are shown in (c). In a corresponding biplane transoesophageal colour-​ coded view the colour mirror artefacts of the aortic regurgitation (green lines) are shown in (d).

long-​axis view is additionally characterized by the tip of the cardiac apex, which is directly below the transducer surface and the centre of the mitral valve in the centreline of the scanning sector. The centred display of the left ventricle is essential for the correct documentation of the apical 2-​and 4-​chamber view by rotation of the transducer without tilting and flipping at the correct apical transducer position. If the centreline of the left ventricle is not centred in the sector of the apical long-​axis view, rotation of the transducer obviously will produce foreshortening views of other sectional planes of the left ventricle. Oblique apical views in normal hearts and failing standardization can be checked by the configuration of the apical shape of the left ventricular cavity. In normal hearts with a normal electrocardiogram, the apex of the left cavity shows a peaked, ‘gothic’ configuration (early ‘gothic’ in the 4-​chamber view, mid ‘gothic’ in the long-​axis view, and late ‘gothic’ in the 2-​chamber view). In normal hearts a ‘Romanic’ configuration is obtained due to foreshortening views. Due to guiding to the apical transducer position by sliding down from the parasternal long-​axis view to the apical long-​axis view, the apical transthoracic echocardiographic examination should start with the two-​dimensional imaging of the left ventricle in the apical long-​axis view (E Fig. 1.21a–​b). The apical long-​axis view

of the left ventricle is normally perpendicular to the commissure of the mitral valve. Thus, the long-​axis view shows the functional division of the left ventricle into the complete inflow chamber during diastole at fully opened mitral valve and the movement of the anterior mitral leaflet close to the anterior septal wall, as well as into the complete outflow chamber during systole by complete closure of the mitral valve. Monoplane planimetry of the left ventricle is performed using the apical long-​axis view for estimation of global left ventricular function by determination of the ejection fraction. The apical long-​axis view is also used for visual analysis of regional wall motion in the posterior and anteroseptal regions, as well as for morphological evaluation of the mid scallops of the mitral valve (A2-​/​P2-​scallop). The 2D-​view is followed by the colour-​coded apical long-​axis view (E Fig. 1.21c–​d) to assess mitral and aortic valve function qualitatively. Because the long-​axis view shows best the blood flow direction into and out of the left ventricle, determinations of proximal jet width or vena contracta, as well as proximal isovelocity surface areas in the presence of turbulent flow at the mitral and aortic valve can usually be well performed in this sectional plane—​especially for central mitral and aortic lesions. According to guidelines, jet morphology and jet size of mitral and aortic regurgitation is not recommended anymore for assessing the

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.12  Profile view of a Medtronic Hall

prosthetic valve in mitral position (a) presenting mirror artefacts (green lines) and attenuation artefacts (blue arrows). In the perpendicular view (b) refraction artefacts can be demonstrated (red arrow). The prosthesis itself acts as the strong reflector producing all artefacts. The transoesophageal long-​axis view of a mechanical prosthesis in aortic position (c and d) displays the mirror artefact of the prosthesis projected into the right ventricular outflow tract is shown in c. In addition the side lobe artefact of the distal part of the prosthesis is shown in d.

Table 1.2  Common artefacts observed in echocardiography Artefact type

Mechanism of the generation of the artefact

Identification of artefact (including examples)

Mitigation of the problem

Reverberation artefact

Reflection of proportions of the ultrasound wave on its way back to the transducer by a second or multiple strong reflectors. The interpretation of the artificial reflected structure by assuming normal ultrasound wave propagation is creating a second image or multiple additional images in a larger distance of the real image—​The distance between the real image of the reflected structure and the artefacts correspond to the distance between the structure and the reflectors.

Strong reflector(s) should be identified Alteration and changing of the transducer by parallel movement of the artefact(s) position to avoid the strong reflectors and the true structure as well as by higher within the scanning plane. echogenicity of the true structure in It is important to mention that the comparison to the artefact (false ‘thrombus reflectors have not to be documented formation’ in the left atrium and left atrial in the sectional plane. Due to the appendage, false dissection flap in the three-​dimensional propagation of the ascending aorta, false intracardiac tumours). ultrasound waves the strong reflectors can be detected only by rotation of the sectional plane.

Comet tail artefact

Several repetitive strong reflectors can create a complex reverberation. Two or more strong reflectors which are very close to each other induce multiple reflections of the sound wave between each other. Thus, transit times between the reflectors induce multiple images behind the true structure.

Strong reflectors at the origin of the comet tails should be detected to explain the phenomenon (aortic wall, posterior epicardium in the parasternal view, mechanical valves, leads of cardiac devices, lung comets).

Alteration and changing of the transducer position to document the changing of the position of the comet tail artefacts. Normally these artefacts are easily to identify. However, they impede the view behind the origin of these artefacts. (continued)

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Table 1.2  Continued Artefact type

Mechanism of the generation of the artefact

Identification of artefact (including examples)

Mitigation of the problem

Mirror image artefact

The mechanism of mirror images is similar to reverberation artefacts. Again, a strong reflector—​normally in the presence of a good acoustic window—​is necessary to produce mirroring. The ultrasound wave reflected from distal strong reflector will be again reflected by the cardiac structures on its way back, which produces an image formation of an identical mirror-​inverted image distal to the original structure.

Mirror artefacts can be identified by parallel mirror-​inverted movements of cardiac structures. The most common strong reflectors of mirror images are the posterior epicardium in the parasternal view and the wall of the descending aorta in transoesophageal echocardiography. (Mirror artefacts mimic pleural effusion or descending aneurysms in the far field).

Alterations and changing the angulation of the scanning plane can mitigate the effects of the strong reflector.

Side lobe artefact

Side lobe artefacts are related to the ultrasound beam properties and the ultrasound equipment, because the side lobe reflections will be analysed as central lobe reflections. Thus, a broad signal with the curvature of the radius of the sector will be created. Thus, the original structure is enlarged on both sides producing a circumferential arc like structure.

This artefact is characterized by a very Changing of the imaging modalities strong reflector and the circular artefact between harmonic and fundamental lines. (misinterpretation of e.g. vegetations imaging. in calcified heart valves, of dissection flaps in the ascending aorta, of flow signals through the interatrial septum mimicking a foramen ovale).

Beam width artefact

Beam width artefacts are also related to the ultrasound beam properties. The ultrasound beam is hourglass shaped with the most narrowing at the focal zone. If a strong reflector is present in the near or far field, which have poorer lateral and elevation resolution, this reflector can produce an artefact in the focus region.

The detection of a strong reflector is helpful for the explanation of beam width artefact. Beam artefacts will be observed in the presence of severe calcifications, pacemaker leads and prosthetic valves. (misinterpretation of vegetations or thrombus formation in cardiac cavities).

Alteration of the acoustic window and changing of the focus area. In addition sometimes reducing of 2D gain can be helpful.

Refraction artefact

Refraction often occurs at strong reflectors with curved surface which are not perpendicular to the ultrasound beam lines. Thus, some structures act like a lens and the reflected waves are bent. Thus, a second structure from a different location is visualized.

Refraction artefacts will be depicted as doubled images—​mostly mirror-​inverted. Duplication of the prosthetic valves in projection into cardiac cavities are the most observed refraction artefacts. Moreover, it is easy to recognize as anatomically the duplicated structure cannot exist.

Double images can be avoided by scanning from different positions. If the surface of the reflectors is almost parallel to the ultrasound beam, the artefact will disappear.

Attenuation artefact

Acoustic shadowing is characterized by a strong reflector which impedes the view behind it. The surface of the strong reflector is usually extremely bright and distal to this signal the attenuating is visualized as a dark comet-​like structure. Multiple reflectors in the near field can produce attenuation by reverberation in the far field.

Calcification, ribs, and metallic material are examples of inducing acoustic shadowing. Lung tissue and breast implants can induce bright attenuation artefacts.

The occurrence of these artefacts can only be avoided by scanning with other planes beside the reflectors. Sometimes in the presence of shadowing increasing of 2D gain can be helpful.

Near field clutter has to be assumed in all diffuse signals in the near field. Often apical left ventricular thrombus formation is assumed in apical views or aortic and left atrial appendage thrombus formation in transoesophageal echocardiography.

Near field clutter can be mitigated by switching from fundamental to harmonic imaging in transoesophageal echocardiography. It can be unmasked by elucidating the respective cavity by colour flow Doppler or contrast echocardiography.

Near field clutter These artefacts are induced by repeated artefact oscillation of the transducer itself.

severity of mitral and aortic regurgitation. The derivations of the pulsed-​wave Doppler spectra of the inflow and outflow tract of the left ventricle should be performed in the apical long-​axis view due to the clear positioning of the sample volumes (E Fig. 1.21e–​f ). The sample volume of the pulsed-​wave Doppler spectrum at the mitral valve for characterizing left ventricular inflow should be positioned in the region of the transition of the mitral leaflets to the chord strands (about 10–​15 mm towards the ventricle from the mitral valve plane) in the centre of the flow direction into the

left ventricle. High-​quality pulsed-​wave Doppler spectra are depicted by bright contours at the maximum velocities. The sample volume of the pulsed-​wave Doppler spectrum at the left ventricular outflow tract has to be positioned in front of the aortic valve (about 5–​10 mm towards the left ventricle from the aortic valve plane). The pulsed-​wave Doppler spectrum of the left ventricular inflow is necessary for characterization of diastolic function by the E/​A-​ratio, as well as for calculation of E/​E′; the pulsed-​wave

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.13  Standardized grey-​scale parasternal long-​axis view during systole (a) and diastole (c), as well as the corresponding colour-​coded images during systole (b) and diastole (d). Additional comments in the text.

Fig. 1.14  Illustration for display of the right ventricular inflow tract and right ventricular outflow tract. Starting from the standardized parasternal long-​axis view (red arrow and red surrounding), the right ventricular inflow tract is displayed by medial tilting (green arrow and green surrounding) of the sectional plane (a—​ systole, b—​diastole), the right ventricular outflow tract by lateral tilting (blue arrow and blue surrounding) of the sectional plane (c—​systole, d—​diastole). The corresponding colour-​coded views are displayed in (e–​h). Additional comments in the text.

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Fig. 1.15  Display of a standardized M-​mode sweep (a). The correct transducer position is documented by the M-​mode sweep by a horizontal line between

the ventral border of the anteroseptal septum and the ventral border of the aortic root (dotted line). Short-​axis views are defined by the accurate cross-​section through the left ventricular attachment of the papillary muscles (b), through the papillary muscles (c), through the chord heads as well as the chord strands (d), through the mitral valve (e), through the interatrial septum and the left ventricular outflow tract (f), through the aortic valve (g), the aortic root and the proximal ascending aorta (h), as well as by a nearly longitudinal plane through the pulmonary trunk and the bifurcation of the pulmonary arteries (i). The red arrows show the position of the respective short-​axis view in a M-​mode sweep. Additional comments in the text.

Fig. 1.16  Illustration of potential errors of measurements for left ventricular dimensions and wall thicknesses due to non-​standardization. If the parasternal

transducer position is too caudal and/​or too lateral, the aortic root drops down on the right side of the sector. This induces too large dimensions of the left ventricular cavity and of the wall thickness (left side—​differences are displayed by the white arrows). Measurements using long-​axis views can be performed using secant-​like sectional planes which induce too small dimensions of the left ventricular cavity and too large dimensions of the wall thickness (right side—​ differences are displayed by the white arrows). Additional comments in the text.

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.17  The standardized parasternal short-​axis

view at the mid-​papillary level. Additional comments in the text.

Fig. 1.18  The standardized

parasternal short-​axis view at the mitral valve level. Additional comments in the text.

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Fig. 1.19  The standardized parasternal short-​axis view at the aortic valve level. Additional comments in the text.

Doppler spectrum of the left ventricular outflow tract is mandatory for calculation of cardiac output or shunt volumes in case of communication defects, as well as for calculation of aortic stenotic valve area according to the continuity equation. In the presence of turbulences at the mitral and aortic valves, the standard documentation should be completed by continuous wave Doppler spectra over the mitral and the aortic valves. The continuous wave Doppler spectrum over the mitral valve is necessary for determination of the velocity time integral in the presence of mitral valve stenosis for determination of mean and maximum pressure gradients, the determination of the stenotic and regurgitant velocities, as well as for calculation of the parameter dp/​dt for estimation of global left ventricular function. The continuous wave Doppler spectrum over the aortic valve is necessary for estimating aortic stenosis severity by determining the mean and maximum pressure gradients and for calculation of aortic stenotic valve area according to the continuity equation. For semi-​quantification of aortic regurgitation, the pressure half-​ time method is used at the deceleration border of the regurgitant velocities.

By an approximately 60° clockwise rotation of the transducer, starting from the standardized apical long-​axis view, the correct apical 2-​chamber view is obtained (E Fig. 1.22a–​b). The sectional plane of the apical 2-​chamber view is characterized by the left ventricular cavity tip, the inferior left ventricular wall at the left side of the cavity, the anterior left ventricular wall at the right side of the cavity, the centre of the mitral valve in its commissural plane, the cross-​sectional coronary sinus in the region of the inferior mitral ring, the left atrium and the left atrial auricle cranial to the mitral ring and the opening of the upper left pulmonary vein cranial to the left atrial auricle. Near the anterior region the P1-​scallop of the mitral valve is depicted, near the inferior region the P3-​scallop. In the centre of the mitral valve the A2-​scallop is normally seen. The apical 2-​chamber view is used for visual assessment of global and regional left ventricular function in the inferior and anterior regions of the left ventricular wall and for the morphological evaluation of the mitral valve. The colour-​coded 2-​chamber view is suitable for characterization of the defect localization in mitral valve regurgitation (E Fig. 1.22c–​d).

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.20  The standardized parasternal short-​axis view through the pulmonary valve and the pulmonary trunk at systole (a) and diastole (b). The

corresponding colour-​coded views are displayed in (c) and (d). In (e) the pulsed-​wave Doppler spectrum of the right ventricular outflow tract is shown. Additional comments in the text.

After modifying the hand position of the transducer to enable a further approximately 60° clockwise rotation of the transducer, this isolated rotation will be performed from the correctly set apical 2-​chamber view to get the standardized apical 4-​chamber view (E Fig. 1.23a–​b). The correct apical 4-​chamber view is characterized by the left ventricular cavity tip, the inferoseptal left ventricular wall at the left side of the cavity, the lateral left ventricular wall at the right side of the cavity, the centre of the mitral valve (A2-​scallop, P2-​scallop near to the P1-​scallop), the interventricular and interatrial septum, the cardiac crux, the septal and the anterior leaflet of the tricuspid valve, the inflow tract of the right ventricle, the free right ventricular wall and the left and right atrium. It is essential that the origin of the anterior mitral leaflet and the septal leaflet of the tricuspid valve is almost at the same point near the cardiac crux. The standardized 4-​ chamber view does not show parts of the left ventricular outflow tract or the longitudinal sectional plane of the coronary sinus. The apical 4-​chamber view is used for visual assessment of global and regional left ventricular function in the inferoseptal and lateral regions of the left ventricular wall and for the morphological evaluation of the central mitral valve.

Using the 2-​and 4-​chamber views, quantitative assessment of left ventricular function is performed by left ventricular volume analysis and determination of left ventricular ejection fraction using the Simpson’s rule. It is recommended to check the longitudinal length of the ventricle at end-​diastole in both views before starting planimetry. If, for example, the longitudinal length of the 4-​chamber view is more shortened than 10 mm in comparison to the 2-​chamber view, it is obvious that the 4-​chamber view has to be foreshortened. The colour-​coded 4-​chamber view (E Fig. 1.23c–​d) is necessary for characterization of the defect localization in mitral valve regurgitation and for semi-​ quantification of the tricuspid valve regurgitation by its vena contracta (E Fig. 1.24a–​c; E Fig. 1.24d–​f ). For complete semi-​quantification of tricuspid valve regurgitation its vena contracta has to be additionally measured in the apical right ventricular inflow tract view derived by tilting the apical long-​axis view to the medial regions (E Fig. 1.24g–​i). In the presence of turbulences at the tricuspid valve, the continuous wave Doppler spectra over the tricuspid valve have to be documented. The continuous wave Doppler spectrum over the tricuspid valve is necessary for

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Fig. 1.21  Standardized grey-​scale apical long-​axis view during systole (a) and diastole (b), as well as the corresponding colour-​coded images during systole

(c) and diastole (d). The pulsed-​wave Doppler spectrum of the left ventricular inflow through the mitral valve (e) and of the left ventricular outflow tract (f) is displayed in the middle of the illustration. Additional comments in the text.

estimating the right ventricular systolic pressure according to the simplified Bernoulli equation, which corresponds to the systolic pulmonary pressure if no pulmonary stenosis is present. Furthermore, the maximum velocity of tricuspid valve regurgitation is necessary for estimation of the pulmonary valvular resistance. The 4-​chamber view is also used for the acquisition of the pulsed tissue Doppler spectra for the calculation of E/​E′. The sample volume is positioned at the basal inferoseptal and lateral myocardium near the mitral annulus (E Fig. 1.25a–​d). E′ for calculation of the E/​E′-​ratio is the mean E′ of both values determined at the basal inferoseptal and lateral left ventricular wall. The 4-​chamber view is also used for grey-​scale and colour-​coded imaging of the upper right pulmonary vein for documentation of the pulsed-​wave Doppler spectrum of the pulmonary vein flow for analysis of diastolic function. The sample volume has to be positioned into the left atrium 10–​15 mm ahead of the entry of the pulmonary vein. The pulsed-​wave Doppler spectrum has to be acquired in low pulse repetition frequency mode to prevent overlapping of the

signals of the flow through the mitral valve and the signals of the pulmonary vein (E Fig. 1.26a–​e). For the documentation of the anterolateral and posteromedial commissure of the mitral valve, two further oblique views of the apical 4-​chamber view have to be adjusted (E Fig. 1.27). The documentation of the P3/​A3 scallops of the mitral valve (= posteromedial commissure) is performed by tilting the transducer to the dorsal region of the left ventricle, which will show the dorsal mitral annulus with the target structure of a longitudinal section of the coronary sinus (E Fig. 1.27a–​d). The documentation of the P1/​A1 scallops of the mitral valve (= anterolateral commissure) is possible by tilting the transducer to the ventral region of the left ventricle, which will show the 5-​ chamber view (E Fig. 1.27e–​h). In the 5-​chamber view the left ventricular outflow tract and parts of the aortic valve are visualized. The 5-​chamber view is an oblique view through the left ventricle, which shows the anteroseptal and anterolateral basal segments of the left ventricular wall and the inferoseptal and lateral apical segments of the left ventricle. The target structure of the 5-​chamber view is the left ventricular outflow tract. Both

Standardized data ac qu i si ti on i n tr a n sthor aci c echo ca rdi o g r a ph y

Fig. 1.22  Standardized grey-​scale

apical 2-​chamber view during systole (a) and diastole (b), as well as the corresponding colour-​coded images during systole (c) and diastole (d). Additional comments in the text.

views should also be documented using colour-​coded Doppler to analyse the localization of mitral valve regurgitation. Subcostal and suprasternal scanning should be performed with the patient in strict supine position. Subcostal scanning should start with the subcostal 4-​chamber view, which is easily adjusted by holding the transducer with the orientation of the notch in the same direction as in the apical

4-​chamber view during inspiration of the patient (E Fig. 1.28a–​ b). The subcostal 4-​chamber view shows the same cardiac structures as the apical 4-​chamber view. A counter-​clockwise rotation shows the subcostal short-​axis views. The perpendicular view to the interatrial septum in the subcostal short-​axis view of the aortic valve is suitable for the detection of interatrial communication defects by colour-​coded Doppler imaging (E Fig. 1.28c–​f ).

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Fig. 1.23  Standardized grey-​scale

apical 4-​chamber view during systole (a) and diastole (b), as well as the corresponding colour-​coded images during systole (c) and diastole (d). Additional comments in the text.

Subcostal short-​axis views of the mitral valve and the left ventricle at mid-​papillary level can replace the parasternal short-​axis views for analysis of the heart if the parasternal window is not sufficient (E Fig. 1.29a–​h). The right ventricular inflow and outflow tract, as well as the pulmonary trunk and the pulmonary bifurcation can be well visualized by the subcostal approach. Due to the excellent Doppler angle, Doppler spectra through the pulmonary valve can be achieved in this view (E Fig. 1.30a–​e). By counter-​clockwise rotation from the subcostal 4-​chamber view the longitudinal section of the inferior caval vein should be documented for estimation of the preload of the right ventricle (E Fig. 1.31a–​b). In the presence of normal right atrial pressure, the central venous pressure is normal, which can be documented

by pulsatile wall movement and a complete breath-​dependent inspiratory collapse of the inferior caval vein. The right atrial pressure is increased in patients with cardiac stasis on the right side, documented by partial collapse or a complete loss of collapse of the inferior caval vein during deep inspiration.

Principles of transoesophageal echocardiography—​practical aspects A transthoracic echocardiography should be generally performed prior to a transoesophageal echocardiography, if it is possible. The main reason for the transthoracic pre-​examination in adult

Principles of t rans oes ophag ea l echo ca rdi o g r a phy — pr acti c a l aspe c ts

Fig. 1.24  The colour-​coded four-​chamber view for qualitative and semi-​quantitative analysis of tricuspid valve regurgitation during systole (a) and diastole

(b). The continuous wave Doppler spectrum of tricuspid valve regurgitation is given in (c). For semi-​quantification of moderate and severe tricuspid valve regurgitation two views are necessary. In an example of a combined tricuspid valve disease the colour-​coded 4-​chamber view is displayed during systole (d) and diastole (e), as well as the view of the right ventricular inflow tract by medial tilting from the apical long-​axis view during systole (g) and diastole (h). In both views the vena contracta of a tricuspid valve regurgitation has to be determined for semi-​quantification during systole. The corresponding continuous wave Doppler spectra of the tricuspid valve regurgitation are given in (f) and (i). Additional comments in the text.

patients is the fact that multiple cineloops and Doppler spectra can be achieved and documented in a high and often better image quality in the transthoracic than in the transoesophageal approach. This mainly concerns the short-​axis views of the left ventricle and the mitral valve, which often will be visualized by oblique views in the transgastric documentation and the Doppler spectra of the left heart, which will not show optimal Doppler angulations in the transoesophageal echocardiography. This is very important for all calculations using Doppler parameters. If these parameters are falsified by incorrect Doppler angulations, calculation of pressure gradients, stroke volumes, shunt volumes, and stenotic areas using the Bernoulli or continuity equation will be wrong. Therefore it is obvious that a sufficient transthoracic echocardiography prior to the transoesophageal investigation can significantly shorten the procedure time of transoesophageal echocardiography.

For transoesophageal echocardiography some prerequisites have to be fulfilled. The preparation of the patient for the procedure includes an ECG, blood pressure and oxygen saturation monitoring, a venous line for sedation, contrast administration, drug administration in the event of complications, the availability of emergency and resuscitation equipment, as well as a suction system. The patient should have an empty stomach, dental fixtures should be removed and a bite guard should be used to protect the shaft of the probe. A local oropharyngeal anaesthesia with lidocaine spray is often sufficient for intubation of the oesophagus. If additional sedation is needed, intravenous administration of midazolam (0.075 mg/​kg) can be added in stable patients. It is obvious that lower sedation doses should be used in patients with severe heart failure or in patients with other compromising diseases. The transoesophageal echocardiography is normally performed in the left lateral position. During intubation of the probe,

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Fig. 1.25  Illustration of a colour-​coded tissue Doppler 4-​chamber view during systole (a) and diastole (b) and the corresponding tissue pulsed-​wave Doppler spectra at the basal septal (c) and lateral (d) myocardium near the mitral annulus. Additional comments in the text.

Fig. 1.26  Illustration of a deep grey-​scale 4-​chamber view during systole (a) and diastole (b) and the corresponding colour-​coded 4-​chamber view during systole (c) and diastole (d). The pulsed-​wave Doppler spectrum of the flow in the right upper pulmonary vein is displayed in (e). Additional comments in the text.

Principles of t rans oes ophag ea l echo ca rdi o g r a phy — pr acti c a l aspe c ts

Fig. 1.27  Illustration for analysis of mitral valve regurgitation affecting the commissures. In the middle of the illustration the standardized 4-​chamber view is

displayed during diastole and during systole (red surrounding) and its sectional plane is displayed in a parasternal short-​axis view (red arrow). For analysis of the posteromedial commissure the transducer has to be tilted to the dorsal region of the left ventricle showing a longitudinal section through the coronary sinus. The illustration shows the corresponding colour-​coded images during systole (a) and diastole (b), as well as the grey-​scale images during systole (c) and diastole (d). For analysis of the anterolateral commissure the transducer has to be tilted to the ventral region of the left ventricle showing the left ventricular outflow tract. The illustration shows the corresponding colour-​coded images during systole (e) and diastole (f), as well as the grey-​scale images during systole (g) and diastole (h). Additional comments in the text.

the tip of the probe has to be unlocked, regarding flexion and extension, to avoid injury to the oesophageal wall. After the examination the probe has to be disinfected as well as inspected for damage according to the international guidelines. The insertion of the probe is the most uncomfortable moment for the awake or slightly sedated patient. Assistance during the intubation is helpful to enable the most convenient mode of introduction of the probe (E Figs. 1.26–​1.27). The user-​ operated actuator should be held by the assistant directly above the patient in the vertical direction with the shaft leading downwards (E Fig. 1.33a–​b). Then, the shaft is touched by the operator with the right hand at the distal shaft near the movable tip (E Fig. 1.33b–​c). The distal ending of the unlocked probe is curved and adapted to the curvature of the oropharynx (E Fig. 1.33c). The left hand of the operator is free for manipulating the tip of the probe during introduction to the oral cavity. The

advantage of this setting is that by pushing the probe forward into the oesophagus, the tip, as well as the shaft, of the probe will follow the natural course of the upper pharyngeal isthmus without inducing unnecessary forces to the wall of the pharynx and the upper oesophagus. The fingers of the left hand will guide the tip of the probe. If the bite guard has to be positioned between the teeth during insertion, the second finger should be laid across the tongue. Then, the probe can be fixed to the back of the pharynx, but positioned at the ridge in the middle of the tongue for the best possibility of introduction into the proximal oesophagus (E Fig. 1.34a). If the patient tolerates the introduction procedure without the bite guard, the second and third finger can be used for introduction of the probe to fix the probe at the ridge in the middle of the tongue (E Fig. 1.34b). The bite guard, which during this manoeuvre was at the shaft of the probe, should be positioned between the teeth after insertion of the probe.

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Fig. 1.28  Standardized grey-​scale apical 4-​chamber view during systole (a) and diastole (b). Standardized subcostal short-​axis view at the aortic valve level during systole (c) and diastole (d), as well as the corresponding colour-​coded images during systole (e) and diastole (f). Additional comments in the text.

Standardized data acquisition in transoesophageal echocardiography The sequence of the transoesophageal image acquisition and documentation depends on the individual situation. If there is no time limit due to emergency, cardiac or respiratory failure, cough or vomiting, agitation or high temperature, the transoesophageal investigation can be performed according to anatomical issues starting with the transgastric views followed by the oesophageal views with retraction of the probe. If there is a time limit, the investigation should focus on the target lesion and additional important findings. In conventional settings with high-​quality transthoracic pre-​investigations and sufficient acquisition of all necessary Doppler spectra by the transthoracic approach, documentation of the transgastric views can normally be spared with respect to the patient’s comfort. Important medical indications for a transoesophageal echocardiography are the accurate visualization of cardiac structures, which cannot be analysed by

transthoracic echocardiography, and the clarification of issues which were the cause for the transoesophageal procedure. Then, depending on the patient’s tolerance and further circumstances, the transoesophageal study should be performed completely, if it is possible. Most of the transoesophageal cardiac views are characterized by the left atrium nearest to the transducer. All standard views should be documented as 2D grey-​scale cineloops, as well as colour-​coded 2D cineloops, to document flow phenomena at the valves or other special cardiac structures. Due to the higher frequencies used in transoesophageal echocardiography, the spatial resolution is normally better than in transthoracic echocardiography. The small layers of the oesophageal and left atrial wall result in an almost direct proximity to the heart. Thus, transoesophageal echocardiography is normally performed in the fundamental mode due to the absence of tissue interferences of the ultrasound. The transoesophageal study should normally start in the transverse position (0°) with a 5-​chamber view or an oblique foreshortened 4-​chamber view in the lower transoesophageal

Standardized data ac qu i si ti on i n tr a n s oes ophag ea l echo ca rdi o g r a ph y

Fig. 1.29  Standardized subcostal short-​axis view at the mitral valve level during diastole (a) and systole (b), as well as the corresponding colour-​coded

images during diastole (c) and systole (d). Standardized subcostal short-​axis view at the mid-​papillary level during diastole (e) and systole (f), as well as the corresponding colour-​coded images during diastole (g) and systole (h). Additional comments in the text.

Fig. 1.30  The standardized subcostal short-​axis view through the pulmonary valve and the pulmonary trunk at diastole (a) and systole (b). The corresponding colour-​coded views are displayed in (c) and (d). In (e) the pulsed-​wave Doppler spectrum of the right ventricular outflow tract is shown. Additional comments in the text.

29

Fig. 1.31  The subcostal longitudinal view of the inferior caval vein during expiration (a) and inspiration (b). Additional comments in the text.

Fig. 1.32  The suprasternal view of

the aortic arch using grey-​scale mode (a) and colour-​coded imaging (b). Additional comments in the text.

Fig. 1.33  Holding of the actuator and the shaft of the transoesophageal probe at the beginning of the investigation. An assistant during the intubation is

helpful to enable the most convenient mode of introduction of the probe (a). The user-​operated actuator should be held by the assistant directly above the patient in a vertical direction with the shaft leading downwards (a). The shaft is touched by the operator with the right hand at the distal shaft near the movable tip (b). The distal ending of the unlocked probe is curved to adapt to the curvature of the oropharynx (c). Additional comments in the text.

Standardized data ac qu i si ti on i n tr a n s oes ophag ea l echo ca rdi o g r a ph y

Fig. 1.34  Directly before introducing the probe the left hand of the operator is free for manipulating the tip of the probe during introduction to the oral cavity.

The fingers of the left hand will guide the tip of the probe. If the bite guard has to be positioned between the teeth during insertion, the second finger should be laid across the tongue (a). Then, the probe can be fixed to the back of the pharynx, but positioned at the ridge in the middle of the tongue with the best possibility to introduce into the proximal oesophagus. If the patient can tolerate the introduction procedure without the bite guard, the second and third fingers can be used for introduction of the probe to fix the probe at the ridge in the middle of the tongue (b). Additional comments in the text.

approach (E Fig. 1.35a–​d). With a minimal deeper insertion of the probe, the longitudinal section of the coronary sinus can be visualized (E Fig. 1.35e–​h). The standardized 4-​chamber view is obtained by a rotation of the plane of about 0°–​40° (E Fig. 1.36a–​ b), straightening the tip of the probe and retracting the probe to the mid-​oesophageal window to get the apex into the centre of the scanning sector. The transoesophageal 2-​chamber view is shown by rotating the plane a further 60° without any movement of the tip and/​or the shaft (60°–​100°) (E Fig. 1.36c–​d). Then, the left ventricular apex is still in the centreline of the scanning sector. The transoesophageal long-​axis view is obtained by further plane rotation of about 60° (120°–​160°) (E Fig. 1.36e–​f ). The angle distance between the views is like in transthoracic echocardiography—​60° if the left ventricular apex is in the centre of the scanning sector. If this is not possible and the left ventricular apex is rotating from the right side of the sector in the 4-​chamber view to the left side of the sector in the long-​axis view, which occurs if the correct position in the upper oesophagus cannot be achieved, the angle differences between the planes of the left ventricle will change. This is the reason why the 2-​chamber view in transoesophageal echocardiography often seems to be perpendicular to the long-​ axis view. The normal 60°-​angle difference between the standardized views of the left ventricle can be documented by the triplane approach, which will show exactly the standardized views with 60°-​angle difference if the left ventricular apex is centred in the scanning sector (E Fig. 1.36g–​h). An oblique 2-​chamber view, which is obtained by deflecting the tip of the probe, normally enables the documentation of a longitudinal section of the left atrial appendage and the upper left pulmonary vein (E Fig. 1.37a–​e). This view is used for acquisition of the pulsed-​wave Doppler spectra of the velocities of the left atrial appendage and the pulmonary venous inflow. The Doppler spectrum of the velocities of left atrial appendage is necessary for risk estimation of thromboembolic events and the Doppler spectrum of the pulmonary vein is necessary for analysis of diastolic function, as well as for estimation of the severity of mitral valve regurgitation. The left atrial appendage should be visualized at least in a second plane perpendicular to this view to detect possible

thrombus formations. Using conventional echocardiography, the left atrial appendage has to be positioned in the centre of the sector by deflecting the probe (E Fig. 1.38a–​c). Using multidimensional probes, this second plane can be achieved by the biplane scanning mode. The aortic short-​axis view is also obtained by further flexion of the tip of the probe taking the 2-​chamber view as the starting view. In addition to the morphological analysis of the aortic valve, the aortic short-​axis view (E Figs. 1.31d and 1.32a) also shows the region of the oval fossa to detect a patent foramen ovale, which is located at the connection of the interatrial septum with the aortic valve annulus. With rotation from 50–​75° to 120–​135° the longitudinal intersected channel of the patent foramen ovale can be visualized (E Fig. 1.38d–​f). In addition, colour-​coded Doppler can be used or contrast can be administrated to document a communication defect. An additional long-​axis view of the aortic valve (120–​135°) should be documented from the most upper oesophageal approach to display the best possible view of the ascending aorta (E Fig. 1.39b). The perpendicular short-​axis view of the ascending aorta (again 60–​75°) displays the cross-​sected ascending aorta, as well as the bifurcation and origin of the right pulmonary artery (E Fig. 1.39c–​d). With a clockwise rotation of the probe shaft, the cross-​sected superior caval vein is behind the right upper pulmonary vein (E Fig. 1.39e–​f ). This view is necessary for the detection of upper sinus venosus atrial defects. By rotating the shaft of the transoesophageal probe clockwise from the aortic long-​axis view, the bicaval view can be achieved (E Fig. 1.40a–​b). The bicaval view of the right atrium displays the left atrium at the top followed by the interatrial septum, which is longitudinally intersected and is seen as a nearly horizontal structure. Distal to the interatrial septum the right atrium is displayed. Located on the right side of the sector the orifice of the superior caval vein and the right atrial appendage can be documented, on the left side of the sector the orifice of the inferior caval vein enters the right atrium. The transgastric views will be achieved after positioning the tip of the probe in the upper stomach. For the transgastric approach harmonic imaging is often superior to fundamental imaging due to the larger near field and the longer distance between the transducer

31

Fig. 1.35  The mid-​oesophageal 5-​chamber view during systole (a) and diastole (b) and the corresponding colour-​coded views during systole (c) and diastole (d).

A slight deeper insertion of the probe at 0° displays the inflow of the coronary sinus. The following views of the right atrium and the right ventricular inflow tract are displayed in grey-​scale mode during systole (e) and diastole (f) and in colour-​coded mode during systole (g) and diastole (h). Additional comments in the text.

Fig. 1.36  The mid-​oesophageal 4-​chamber view during systole (a) and diastole (b), the mid-​oesophageal 2-​chamber view during systole (c) and diastole (d), the mid-​oesophageal long-​axis view during systole (e) and diastole (f) and the simultaneous triplane views during systole (g) and diastole (h) to document that angle differences between mid-​oesophageal standardized views with the left ventricular apex near the centreline of the sector are about 60° like the transthoracic views. Additional comments in the text.

Standardized data ac qu i si ti on i n tr a n s oes ophag ea l echo ca rdi o g r a ph y

Fig. 1.37  Oblique mid-​oesophageal 2-​chamber view (a) for visualization of the left atrial appendage (LAA) and the upper left pulmonary vein. The upper left

pulmonary vein is displayed at the right side of the sector by positioning of the LAA in the centre of the sector (b). Colour-​coded imaging of the pulmonary vein (c) facilitates the positioning of the sample volume for flow measurements. In the middle of the figure the pulsed-​wave Doppler spectra of the flow in the LAA with sinus rhythm (e) and in the upper left pulmonary vein (e) are displayed. Additional comments in the text.

and the cardiac structures. The investigation starts with a short-​ axis view of the left ventricle at the mid-​papillary level (0°) (E Fig. 1.40c–​d). If the left ventricle is displayed centrally in the sector, the perpendicular view shows the transgastric left ventricular 2-​ chamber view (90°) with the apex on the left side and the mitral valve on the right side (E Fig. 1.40e–​f ). The inferior wall is in the near field, the anterior wall in the far field. The transgastric long-​ axis view can be displayed by further rotation of the probe to 100°–​ 130° and a minor clockwise rotation of the shaft, which displays the aortic valve on the right side of the sector in the far field (E Fig. 1.41a–​f ). The inflow tract of the right ventricle is also visualized by the perpendicular view (90°) to the left ventricular short-​axis view (0°) after centring the right ventricle in the sector before rotating (E Fig. 1.42a–​d). The transgastric right ventricular longitudinal view displays the right ventricular apex on the left side and the right atrium and the tricuspid valve on the right side of the sector. A further rotation of the probe to 110°–​140° and a minor rotation of the shaft enables the visualization of the inflow and outflow tracts of the right ventricle. The outflow tract and the pulmonary valve are nearly centred in the far field in this view. The transgastric short-​axis view of the mitral valve is a technically difficult view. Often only an oblique view of the mitral valve can be displayed. The short-​axis view of the mitral valve is achieved by slightly withdrawing the probe at 0°–​20° from the mid-​papillary short-​axis view and simultaneous anteflexion of the probe. In this view the anterior mitral leaflet is on the left side of the sector and the posterior leaflet on the right side of the sector.

The posteromedial commissure (A3/​P3) is in the near field, the anterolateral commissure (A1/​P1) in the far field (E Fig. 1.43a–​d). A second possibility to visualize the left ventricular outflow tract is by deep intubation into the gastric fundus with consecutive anteflexion of the tip of the probe. Using this approach, the deep transgastric long-​axis view at about 0° and the deep transgastric 5-​chamber view can be achieved at about 120°–​140° (E Fig. 1.44a–​f). The deep transgastric long-​axis view displays the right ventricular outflow tract on the left side of the sector, the left ventricle on the right side of the sector in the near field, and the aortic valve centrally in the far field. Sometimes the transversely intersected aortic root and proximal ascending aorta are visualized. After the documentation of the cardiac structures and the ascending aorta at the end of the transoesophageal investigation, the probe is turned into the opposite direction to the heart by rotating the shaft about 90°. Starting in the deep oesophagus at the diaphragm, the descending aorta is scanned using short-​axis views (0°) during withdrawal of the probe to the upper oesophagus. In the region of the separation of the left subclavian artery, the probe has to be rotated (10–​60°) to display the descending aorta in short-​axis views (E Fig. 1.45a–​b). The aortic arch is displayed in a short-​axis view after rotation of about 90°. Scanning of the descending aorta is necessary for the detection of plaque ruptures and other aortic pathologies. If pathological findings are present, additional long-​axis views of the descending aorta should be documented.

33

Fig. 1.38  Biplane documentation of a normal left atrial appendage (a, b) and the corresponding pulsed-​wave Doppler spectrum during atrial fibrillation (c).

Documentation of the oval fossa in a short-​axis view at the aortic root level (d). By rotation of the plane to 90° (e) and 107° (f) the channel between the septum primum and secundum is displayed. Additional comments in the text.

Fig. 1.39  Mid-​transoesophageal short-​axis view of the aortic valve (a). Upper transoesophageal long-​axis view of the ascending aorta (b). Upper

transoesophageal views of the ascending aorta and pulmonary artery, as well as the superior caval vein. The short-​axis view of the aortic root and the pulmonary bifurcation is displayed in grey-​scale (c) and colour-​coded mode (d). The short-​axis view of the superior caval vein and the upper right pulmonary vein is displayed in grey-​scale (e) and colour-​coded mode (f). Additional comments in the text.

Standardized data ac qu i si ti on i n tr a n s oes ophag ea l echo ca rdi o g r a ph y

Fig. 1.40  Mid-​transoesophageal bicaval view during systole (a) and diastole (b). Transgastric short-​axis view at the mid-​papillary level during systole (c) and diastole (d). Transgastric 2-​chamber view during systole (e) and diastole (f). Additional comments in the text.

Fig. 1.41  Transgastric long-​axis view during systole (a) and diastole (b), as well as the corresponding colour-​coded views (c, d). The transgastric colour-​coded long-​axis view in a patient with hypertrophic cardiomyopathy with increased systolic (e) and diastolic flow (f). Additional comments in the text.

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Fig. 1.42  Transgastric right ventricular inflow and outflow

tract during systole (a) and diastole (b) and the corresponding colour-​coded views (c, d). Additional comments in the text.

Fig. 1.43  Transgastric short-​axis views at the mitral valve level. Two slightly different sectional planes of the mitral valve are displayed during systole (a, c) and diastole (b, d). Additional comments in the text.

Standard valu es in t ransthor aci c a n d tr a n s oes ophag ea l echo ca rdi o g r a ph y

Fig. 1.44  Deep transgastric long-​axis view during systole (a) and diastole (b) and the corresponding colour-​coded views (c, d). Further colour-​coded views of a patient with hypertrophic cardiomyopathy are displayed during systole (e) and diastole (f). Additional comments in the text.

Fig. 1.45  Mid-​oesophageal short-​

axis view (a) and long-​axis view (b) of the descending aorta. Additional comments in the text.

Standard values in transthoracic and transoesophageal echocardiography M-​mode measurements M-​mode measurements in conventional echocardiography are mainly performed for analysis of left ventricular dimensions and

wall thicknesses, as well as aortic root and left atrial dimensions. For wall thickness measurements to calculate left ventricular mass according to the Penn-​convention and for left ventricular diameter measurements for calculation of the left ventricular ejection fraction according to the Teichholz equation, the myocardial borders will be labelled inner-​edge-​to-​inner-​edge without endo-​and epicardium at the maximum peak of the R-​wave of

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the electrocardiogram. In contrast, according to the American Society of Echocardiography convention, measurements of the left ventricular wall will be performed leading-​edge-​to-​leading-​ edge at the beginning of the QRS complex. In Europe the measurements are normally performed inner-​edge-​to-​inner-​edge. Measurements were performed at a ventricular level between the transition of the papillary muscles to the chords. Left atrial diameter is measured at the time point of early diastole behind the aortic root. Aortic root diameter is measured inner-​edge-​to-​inner-​edge during mid-​systole at the time interval of aortic valve separation. Right ventricular diameter is measured in the M-​mode at the mitral valve level during end-​diastole.

Two-​dimensional measurements

Table 1.3  Echocardiographic parameters and standard values used to quantify cardiac dimensions and function Echocardiographic parameter

Standard value

Left ventricular wall thickness (M-​mode/​2D)

6–​11 mm

Left ventricular end-​diastolic diameter (M-​mode/​2D)

39–​59  mm 22–​32  mm/​m2 25–​33 mm/​m

Right ventricular wall thickness (M-​mode/​2D)

50% stenosis on ICA)

67

86

57

90

99m

Liga 2016 [66]

252

Flow limiting coronary stenoses [(>50% 83 stenosis on ICA) or (30–​50% stenosis on ICA & FFR+) and perfusion defect]

68

NA

NA

SPECT/​PET/​CTA

O-​water PET/​ 64 slice CT Tc SPECT/​ 64 slice CT Tc SPECT/​ 16 slice CT Tc SPECT/​ Dual source CT

*pre-​renal transplant patients, per patient analysis ¥ hybrid SPECT/​coronary CTA only applied for non-​evaluable arteries on coronary CTA µ patient based analysis CAD = Coronary artery disease, CTA = Computed tomography angiography, FFR = Fractional flow reserve, ICA = Invasive coronary angiography, MBF = Myocardial blood flow, N = number, NPV = Negative predictive value, PET = Positron emission tomography, PPV = Positive predictive value, QCA = Quantitative coronary angiography, SPECT = Single photon emission computed tomography

Ca rdiac hy b ri d i m ag i n g of hybrid PET-​MRI imaging is lower than that of PET-​CT or SPECT-​CT, which might be particularly beneficial in younger patients who may need repeated scans [2]‌.

side-​by-​side analysis of images have shown that in almost one-​ third of patients the fused SPECT-​CT or PET-​CT analysis provided added diagnostic information on pathophysiologic lesion severity not obtained by side-​by-​side analysis [62–​66]. The most Clinical impact of cardiac hybrid imaging pronounced incremental value has been found in patients with As just mentioned, it is well established that a comprehensive multivessel disease (E Fig. 9.6) and lesions in distal coronary assessment of CAD requires not only morphologic informa- segments, diagonal branches (E Fig. 9.7), the left circumflex, tion about coronary artery stenosis location and degree but and right coronary arteries as well as in vessels with extensive also functional information on pathophysiologic lesion severity. CAD or substantial calcification on CTA. Due to the variant Eventually, many factors that cannot fully be assessed with cor- coronary anatomy in each individual and the complex disease onary luminology determine whether a given lesion really in- pattern in these patients, hybrid images facilitate correct assignduces a myocardial perfusion defect. The goal of hybrid imaging ment of perfusion defect to a territory subtended by a haemois to provide accurate spatial alignment of coronary angiography dynamically significant stenosis. As hybrid images offered and myocardial perfusion data to improve co-​ localization of superior information with regard to identification of the culprit myocardial perfusion abnormalities and subtending coronary vessel the diagnostic confidence for categorizing intermediate arteries (E Fig. 9.1). The planar projections of coronary angio- lesions and equivocal perfusion defects was significantly imgrams and axial slice-​by-​slice display of cardiac perfusion studies proved. Additional patient groups in which hybrid imaging make a subjective integration of perfusion abnormalities with has been shown to provide complementary information on the coronary anatomy difficult. This may lead to inaccurate allocation presence and localization of atherosclerotic lesions and myocarof the coronary lesion to its subtended myocardial territory, par- dial perfusion abnormalities are those with congenital coronary ticularly in patients with multivessel disease and intermediate se- anomalies [67] and patients with recurrent chest pain after corverity lesions. Hybrid imaging studies have shown that standard onary bypass surgery (E Fig. 9.8) [68]. Furthermore, hybrid distribution of myocardial territories corresponds with the real imaging can identify patients with reduced coronary flow reanatomic coronary tree in only 50–​60% of cases which may cause serve due to microvascular dysfunction without obstructive misleading interpretation [42]. CAD resulting in discordant findings in myocardial perfusion Studies comparing cardiac hybrid imaging with stand-​alone images and coronary CTA [47, 69]. From these studies one can perfusion imaging or coronary CTA have shown promising re- conclude that the greatest added value appears to be the exclusults in the detection of obstructive CAD [43–​59]. A meta-​ sion of haemodynamic significance of coronary abnormalities analysis of 12 diagnostic studies (951 patients in total) [60], found seen on coronary CTA, differentiation of epicardial and microthat pooled sensitivity of hybrid imaging for the detection of CAD vascular disease, as well as correct localization of the culprit ledefined as luminal diameter reduction of at least 50% by ICA was sion causing ischaemia. comparable to that of coronary CTA on per-​patient (91% vs. 90%) The independent prognostic value of coronary CTA and myoand per-​vessel (84% vs. 89%) basis. However, specificity of hybrid cardial perfusion imaging was demonstrated in a multicentre imaging clearly outperformed that of coronary CTA alone on per-​ follow-​up study in more than 500 patients supporting the notion patient (93% vs. 66%) and on a per-​vessel (95% vs. 83%) analyses. that both parameters need to be investigated in patients with CAD There was also a modest improvement in overall diagnostic per- [70]. Another study using hybrid SPECT-​CT imaging showed formance at per-​vessel level (area under the curve 0.97 vs. 0.92). that a matched finding of myocardial ischaemia in a territory A limitation of the meta-​analysis and current studies is that in supplied by a stenotic coronary artery was associated with higher most of them used angiographic stenosis diameter as the refer- risk of death or myocardial infarction than regionally unmatched ence standard instead invasive fractional flow reserve (FFR) and ischaemia and stenosis [71]. Similarly, highest revascularization thus, do not account for the potential discrepancy between sten- rates have been observed in the presence of perfusion abnorosis severity and functional significance of coronary lesions. A mality matched with a stenosis in the subtending coronary artery recent single-​centre prospective study compared hybrid imaging [72]. In a recent study finding of myocardial ischaemia on was with stand-​alone imaging in 208 patients who underwent cor- associated with five times higher risk of death, myocardial infarconary CTA, SPECT perfusion imaging and 15O-​water PET per- tion, or unstable angina as compared with patients in whom stenfusion imaging and ICA combined with measurement of FFR in osis was suspected based on coronary CTA, but PET perfusion all arteries [61]. In this study, the addition of functional imaging imaging did no show ischaemia [73]. These studies provide evito coronary CTA improved specificity, but there was an increase dence that ischaemia at an anatomically appropriate location by in false negative findings that resulted in no overall incremental hybrid imaging can provide incremental information about risk diagnostic benefit as compared with stand-​alone imaging. of adverse events and have an impact on patient management in Although the latter studies provide important clinical in- terms of revascularization decisions. formation about the performance of different imaging modalSeveral studies have shown that CAC imaging has increities, they do not directly show the incremental value of the mental diagnostic and prognostic value over myocardial hybrid imaging. Studies comparing fused hybrid images with perfusion imaging, because of its ability to quantify overall

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(b)

(a)

(d)

Fig. 9.6  Coronary CTA images (curved

multiplanar reconstructions) of a male patient with effort angina. Images of the right anterior descending artery (RCA) (a), left anterior descending artery (LAD) (b), and left circumflex artery (LCX) (c) show several calcified and noncalcified plaques, which suggest significant multivessel disease. Three-​dimensional cardiac hybrid PET-​CT images of anterior (d) and right lateral view (e) shows very different stress perfusion patterns in each vessel region. The perfusion in region supplied by the LCX was normal (red and yellow colour), slightly reduced in region supplied by the LAD (green colour) and severely compromised in region supplied by the RCA (blue colour).

Fig. 9.7  Examples of two clinically similar

symptomatic patients who had also similar findings in the LAD and the first diagonal branch (D1) in CTA (left panels). The patient 1 (upper row) showed in hybrid PET-​CT imaging (right panel) only subtle reduction in territory supplied by D1. The patient 2 (lower row) showed large poorly perfused region covering whole anterior wall supplied by both the LAD and D1.

(c)

(e)

Dedi cated ca rdiac- on ly SPEC T sc a n n e r s

Fig. 9.8  In situations of complex CAD and after

bypass surgery hybrid cardiac imaging provides added value. Coronary CTA may allow visualization of patent bypass grafts but the evaluation of the anastomoses and native arteries remains difficult. A conclusion about haemodynamic relevant lesions can only be reached in conjunction with perfusion. The image documents ischaemia in the right coronary artery territory (blue colour) due to a stenosis at the distal graft anastomosis (red arrow).

atherosclerotic burden [74–​77]. High atherosclerotic burden has been shown to increase the likelihood of obstructive CAD in symptomatic patients [74, 75] and increasing CAC score is associated with a stepwise increase in the risk of myocardial infarction or death in patients with and without ischaemia on perfusion imaging [76]. However, important to note that CAC imaging does not assess the severity of stenosis. Although CAC scan and perfusion images are usually interpreted separately, their fusion is possible and patients with coronary calcification and a matched perfusion abnormality in the territory subtended by the calcified vessel were shown to be at highest risk of cardiovascular events [77].

Myocardial blood flow quantification Myocardial perfusion imaging with PET imaging offers possibility to measure myocardial blood flow quantitatively (in ml/​ min/​g of myocardium) at rest and vasodilator-​stress that allows for calculation of myocardial flow reserve (MFR, ratio of stress over rest myocardial blood flow) [78–​79]. Accurate and reproducible quantification of myocardial blood flow is possible with the most commonly used PET perfusion tracers 15 O-​water, 13N-​ammonia 82Rb [79]. In addition to these, new perfusion tracers labelled with 18F are currently investigated and they may improve availability of PET myocardial perfusion imaging, because due to long half-​life they could be distributed to centres without an on-​site cyclotron [80]. Due to advances in scanner technology it has become possible to include quantification of myocardial blood in standard clinical PET myocardial perfusion protocols [79]. Dynamic datasets used for blood flow quantification can be reconstructed from list-​ mode data, and compartmental modelling to calculate myocardial blood flow is possible with many image analysis software packages.

Stress myocardial blood flow and MFR are consistently reduced in the presence of high grade coronary stenosis associated with abnormal FFR and can be used improve diagnostic accuracy of PET myocardial perfusion imaging [16–​19, 61]. Quantification of myocardial blood flow (MBF) is particularly useful in the detection of multivessel CAD when relative assessment of myocardial perfusion cannot uncover global reduction in perfusion (E Fig. 9.9). Preserved global MFR of more than 2.0 has excellent negative predictive value exclusion of multivessel CAD [16–​19]. In addition to obstructive CAD, abnormal coronary flow reserve (CFR) can be caused by diffuse non-​obstructive coronary atherosclerosis or coronary endothelial/​microvascular dysfunction [81] and it has been shown to predict high coronary risk independently incrementally to the presence and extent of relative perfusion defects in patients evaluated for CAD [82].

Dedicated cardiac-​only SPECT scanners Dedicated cardiac SPECT cameras incorporate highly efficient solid-​state cadmium zinc telluride (CZT) radiation detectors with cardiofocal imaging that yield enhanced count sensitivity [83]. Some of the dedicated cardiac SPECT CZT scanners offer the option of hybrid imaging with CT. Compared to conventional SPECT, these scanners combined with new reconstruction methods provide images with higher contrast and spatial resolution, acquired in shorter time and with reduced radiation dose to the patient [84]. Accumulated data show that diagnostic performance of the new scanners compares favourably with conventional SPECT scanners in the detection of obstructive CAD [78]. High image quality may be particularly useful in the detection of multivessel disease [83] and in obese patients [84]. Importantly, these scanners have been used successfully to perform low and very low radiation dose imaging.

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N ew tech nical devel opments i n nu cl ea r ca rdi ol o g y a n d hy b ri d i m ag i n g (a)

(b)

(c)

(d)

Fig. 9.9  Hybrid images from stress PET-​CT study

in a patient with extensive CAD. The images (a and b) scaled to relative scale where the best perfused region is set to maximum and has the brightest colour (in rainbow scale lowest = blue and highest = red). The hybrid images of anterior (a) and posterior (b) views suggested only minor perfusion abnormalities in the anterior wall. The images scaled according to absolute scale (c and d) (0 ml/​ g/​min = blue and 3.5 ml/​g/​min = red) uncovered global reduction of perfusion. The hybrid images of anterior (c) and posterior (d) views showed severely reduced stress perfusion in the anterior wall but also abnormally low perfusion in other myocardial territories (green colour).

(e)

(a)

(f)

(c)

Resolution Recovery Components

Pixel i

An object close to the collimator will have less blur.

(b)

Projection

Collimator

An object farther from the collimator will have more blur.

Solid angle Voxel j

Fig. 9.10  Resolution Recovery Software for Low Count Density Image Reconstruction: (a) depicts depth dependent blurring of images with an object closer

to the collimator showing less blurring; (b) demonstrates that increasing collimator hole width, decreasing hole length, and increasing septal penetration result in loss of resolution; (c) demonstrates how pixel weights are calculated mathematically, based on the solid angles subtended by the collimator between each detector pixel and each body voxel to apply corrections and enhance image quality. Reproduced from Dorbala S, Ananthasubramaniam K, Armstrong IS, et al. Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging Guidelines: Instrumentation, Acquisition, Processing, and Interpretation. J Nucl Cardiol. 2018;25:1784–​846 with permission from Springer.

Fu tu re pe r spe c t i v e s

Novel cardiac software In addition to novel hardware, several novel software approaches have been developed for reconstruction of reduced count density images (E Fig. 9.10) including iterative reconstruction, resolution recovery, and noise reduction. Iterative reconstruction employs ordered subsets expectation maximization algorithms to reduce image blurring in three dimensions and improve low count density image quality. Resolution recovery methods apply corrections for distance dependent blurring and correct for depth dependent loss of resolution and improve spatial resolution with less noise compared to conventional reconstruction methods. Noise compensation, as opposed to conventional filtered back projection techniques, improve signal-​to-​noise ratio. Enhancement in image quality with the use of these three techniques allows personalized protocols of reduced time imaging, reduced dose imaging, or both. While majority of the novel SPECT scanners are equipped with these software enhancements, a big advantage of these software methods in that they can be applied to improve image quality from old scanners with a much smaller capital investment.

Future perspectives Hybrid imaging has been mainly used and implemented in guidelines for evaluation of CAD [1, 3, 4], In particular, guidelines (a)

(c)

(b)

(d)

recommend that physicians ‘consider functional assessment’ in patients with coronary stenosis of uncertain severity by CTA [4, 85, 86]. However, there is still a need to clarify which patients can benefit most from hybrid imaging, how to optimally combine different modalities, and what is the cost-​effectiveness of hybrid imaging. The fusion of cardiac and coronary anatomy with molecular imaging techniques holds potential for many research applications. An example is hybrid PET-​CT imaging of atherosclerosis that offers an opportunity to combine detailed morphology of atherosclerotic plaques with markers of disease activity, such as uptake of 18 F-​FDG in inflammatory cells (E Fig. 9.11) [25]. 18F-​FDG PET-​ CT has been used successfully to study biology of atherosclerosis and anti-​inflammatory effects of novel atherosclerosis treatments [25, 87]. This approach is possible only with localization of the PET signal with high-​resolution morphological imaging of the coronary arteries using hybrid imaging. In addition to 18F-​FDG, many new PET radiotracers are in development and have been used to investigate different aspects of cardiovascular disease, such as 18F-​fluoride for detection of microcalcification and 68Ga-​DOTATATE targeting somatostatin receptors for the detection of active macrophages in coronary atherosclerotic lesions [88]. Hybrid imaging combining MR with PET is attractive for many reasons, including lack of additional ionizing radiation, tissue characterization properties of MRI and possibility to do simultaneous acquisition with MRI and PET [2, 88]. Hybrid PET-​MRI scanners have been available for short a relatively short period of time and

Fig. 9.11 Focal 18F-​FDG uptake in a patient

with high-​risk plaque morphology in the left main coronary artery in orthogonal fused PET-​CT images (a and b) and a corresponding maximum intensity projection–​reconstructed CTA image of the left main coronary artery non-​calcified plaque (arrow; c), and axial CTA showing a cross-​sectional view (d) of an additional plaque in the right coronary artery manifesting positive remodelling and low attenuation (arrow) in the same subject. Reproduced from Singh P, Emami H, Subramanian S, et al. Coronary Plaque Morphology and the Anti-​ Inflammatory Impact of Atorvastatin: A Multicenter 18F-​Fluorodeoxyglucose Positron Emission Tomographic/​ Computed Tomographic Study. Circ Cardiovasc Imaging. 2016 Dec;9(12) with permission from Wolters Kluwer.

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there is still relatively little clinical data on their incremental value in evaluation of myocardial viability and inflammatory cardiomyopathy [89]. However, development of new PET and MR tracers, targeting different pathological processes, may expand our ability to measure disease activity in the myocardium [88, 89].

Conclusion The newest generation of the hybrid imaging devices have matured to the level that they can be successfully used for clinical

cardiovascular imaging. In addition, software based image fusion has become readily available allowing robust and fast image merging. It is likely that in the near future the primary clinical use of hybrid imaging is in the detection of CAD using CT coronary angiography and nuclear perfusion imaging, but in long term also other molecular imaging applications are entering into clinical cardiology. Dedicated cardiac SPECT scanners [90], novel low count density reconstruction software as well as myocardial blood flow quantitation are novel advancements that have substantially improved nuclear cardiology imaging.

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myocardial perfusion imaging to improve noninvasive detection of coronary artery disease. J Nucl Cardiol 2010; 17: 19–​26. 54. Thomassen A, Petersen H, Diederichsen AC, et al. Hybrid CT angiography and quantitative 15O-​water PET for assessment of coronary artery disease: comparison with quantitative coronary angiography. Eur J Nucl Med Mol Imaging 2013; 40: 1894–​904. 55. Groothuis JG, Beek AM, Brinckman SL, et al. Combined non-​ invasive functional and anatomical diagnostic work-​up in clinical practice: the magnetic resonance and computed tomography in suspected coronary artery disease (MARCC) study. Eur Heart J 2013; 34: 1990–​8. 56. Scheffel H, Stolzmann P, Alkadhi H, et al. Low-​dose CT and cardiac MR for the diagnosis of coronary artery disease: accuracy of single and combined approaches. Int J Cardiovasc Imaging 2010; 26: 579–​90. 57. Donati OF, Scheffel H, Stolzmann P, et al. Combined cardiac CT and MRI for the comprehensive workup of hemodynamically relevant coronary stenoses. AJR Am J Roentgenol 2010; 194: 920–​6. 58. Dong W, Wang Q, Gu S, Su H, Jiao J, Fu Y. Cardiac hybrid SPECT/​ CTA imaging to detect ‘functionally relevant coronary artery lesion’: a potential gatekeeper for coronary revascularization? Ann Nucl Med 2014; 28: 88–​93. 59. Winther S, Svensson M, Jorgensen HS, et al. Diagnostic performance of coronary CT angiography and myocardial perfusion imaging in kidney transplantation candidates. JACC Cardiovasc Imaging 2015; 8: 553–​62. 60. Rizvi A, Han D, Danad I, et al. Diagnostic performance of hybrid cardiac imaging methods for assessment of obstructive coronary artery disease compared with stand-​alone coronary computed tomography angiography: a meta-​analysis. JACC Cardiovasc Imaging 2018; 11: 589–​99. 61. Danad I, Raijmakers PG, Driessen RS, et al. Comparison of coronary CT angiography, SPECT, PET, and hybrid imaging for diagnosis of ischemic heart disease determined by fractional flow reserve. JAMA Cardiol 2017; 2: 1100–​7. 62. Gaemperli O, Schepis T, Valenta I, et al. Functionally relevant coronary artery disease: comparison of 64-​section CT angiography with myocardial perfusion SPECT. Radiology 2008; 248: 414–​23. 63. Santana CA, Garcia EV, Faber TL, et al. Diagnostic performance of fusion of myocardial perfusion imaging (MPI) and computed tomography coronary angiography. J Nucl Cardiol 2009; 16: 201–​11. 64. Slomka PJ, Cheng VY, Dey D, et al. Quantitative analysis of myocardial perfusion SPECT anatomically guided by coregistered 64-​slice coronary CT angiography. J Nucl Med 2009; 50: 1621–​30. 65. Gaemperli O, Schepis T, Valenta I, et al. Cardiac image fusion from stand-​alone SPECT and CT: clinical experience. J Nucl Med 2007; 48: 696–​703. 66. Liga R, Vontobel J, Rovai D, et al. Multicentre multi-​device hybrid imaging study of coronary artery disease: results from the EValuation of INtegrated Cardiac Imaging for the Detection and Characterization of Ischaemic Heart Disease (EVINCI) hybrid imaging population. Eur Heart J Cardiovasc Imaging 2016; 17: 951–​60. 67. Husmann L, Herzog BA, Burkhard N, Valenta I, Weber K, Kaufmann PA. Coronary artery ectasia causing ischemia. Eur J Nucl Med Mol Imaging 2008; 35: 2142. 68. Maaniitty T, Jaakkola S, Saraste A, Knuuti J. Hybrid coronary computed tomography angiography and positron emission tomography myocardial perfusion imaging in evaluation of recurrent symptoms after coronary artery bypass grafting. Eur Heart J Cardiovasc Imaging 2019; 20: 1298–​304. 69. Stenström I, Maaniitty T, Uusitalo V, et al. Frequency and angiographic characteristics of coronary microvascular dysfunction

in stable angina: a hybrid imaging study. Eur Heart J Cardiovasc Imaging 2017; 18: 1206–​13. 70. van Werkhoven JM, Schuijf JD, Gaemperli O, et al. Prognostic value of multislice computed tomography and gated single-​photon emission computed tomography in patients with suspected coronary artery disease. J Am Coll Cardiol 2009; 53: 623–​32. 71. Pazhenkottil AP, Nkoulou RN, Ghadri JR, et al. Prognostic value of cardiac hybrid imaging integrating single-​photon emission computed tomography with coronary computed tomography angiography. Eur Heart J 2011; 32: 1465–​71. 72. Pazhenkottil AP, Nkoulou RN, Ghadri JR, et al. Impact of cardiac hybrid single-​ photon emission computed tomography/​ computed tomography imaging on choice of treatment strategy in coronary artery disease. Eur Heart J 2011; 32: 2824–​9. 73. Maaniitty T, Stenström I, Bax JJ, et al. Prognostic value of coronary CT angiography with selective PET perfusion imaging in coronary artery disease. JACC Cardiovasc Imaging 2017; 10: 1361–​70. 74. Schepis T, Gaemperli O, Koepfli P, et al. Added value of coronary artery calcium score as an adjunct to gated SPECT for the evaluation of coronary artery disease in an intermediate-​risk population. J Nucl Med 2007; 48: 1424–​30. 75. Ghadri JR, Pazhenkottil AP, Nkoulou RN, et al. Very high coronary calcium score unmasks obstructive coronary artery disease in patients with normal SPECT MPI. Heart 2011; 97: 998–​1003. 76. Schenker MP, Dorbala S, Hong EC, et al. Interrelation of coronary calcification, myocardial ischemia, and outcomes in patients with intermediate likelihood of coronary artery disease: a combined positron emission tomography/​computed tomography study. Circulation 2008; 117: 1693–​700. 77. Ghadri JR, Fiechter M, Fuchs TA, et al. Registry for the evaluation of the prognostic value of a novel integrated imaging approach combining single photon emission computed tomography with coronary calcification imaging (REPROSPECT). Eur Heart J Cardiovasc Imaging 2013; 14: 374–​80. 78. Murthy VL, Bateman TM, Beanlands RS, et al. Clinical quantification of myocardial blood flow using PET: joint position paper of the SNMMI Cardiovascular Council and the ASNC. J Nucl Med 2018; 59: 273–​93. 79. Moody JB, Lee BC, Corbett JR, Ficaro EP, Murthy VL. Precision and accuracy of clinical quantification of myocardial blood flow by dynamic PET: a technical perspective. J Nucl Cardiol 2015; 22: 935–​51. 80. Berman DS, Maddahi J, Tamarappoo BK, et al. Phase II safety and clinical comparison with single-​photon emission computed tomography myocardial perfusion imaging for detection of coronary artery disease: flurpiridaz F 18 positron emission tomography. J Am Coll Cardiol 2013; 61: 469–​77. 81. Taqueti VR, Di Carli MF. Coronary microvascular disease pathogenic mechanisms and therapeutic options: JACC state-​of-​the-​art review. J Am Coll Cardiol 2018; 72: 2625–​41. 82. Juárez-​Orozco LE, Tio RA, Alexanderson E, et al. Quantitative myocardial perfusion evaluation with positron emission tomography and the risk of cardiovascular events in patients with coronary artery disease: a systematic review of prognostic studies. Eur Heart J Cardiovasc Imaging 2018; 19: 1179–​87. 83. Agostini D, Marie PY, Ben-​Haim S, et al. Performance of cardiac cadmium-​zinc-​telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM). Eur J Nucl Med Mol Imaging 2016; 43: 2423–​32. 84. Gimelli A, Liga R, Duce V, et al. Accuracy of myocardial perfusion imaging in detecting multivessel coronary artery disease: a cardiac CZT study. J Nucl Cardiol 2017; 24: 687–​95.

Re f e re n c e s 85. Cury RC, Abbara S, Achenbach S, et al. CAD-​RADS(TM) coronary artery disease—​reporting and data system. An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Radiology (ACR) and the North American Society for Cardiovascular Imaging (NASCI). Endorsed by the American College of Cardiology. J Cardiovasc Comput Tomogr 2016; 10: 269–​81. 86. Moss AJ, Williams MC, Newby DE, Nicol ED. The updated NICE guidelines: cardiac CT as the first-​line test for coronary artery disease. Curr Cardiovasc Imaging Rep 2017; 10: 15. 87. Singh P, Emami H, Subramanian S, et al. Coronary plaque morphology and the anti-​inflammatory impact of atorvastatin: a multicenter

18F-​fluorodeoxyglucose positron emission tomographic/​computed tomographic study. Circ Cardiovasc Imaging 2016; 9: e004195. 88. Robson PM, Dey D, Newby DE, et al. MR/​PET Imaging of the Cardiovascular System. JACC Cardiovasc Imaging 2017; 10: 1165–​79. 89. Rischpler C, Nekolla SG, Dregely I, Schwaiger M. Hybrid PET/​MR imaging of the heart: potential, initial experiences, and future prospects. J Nucl Med 2013; 54: 402–​15. 90. Dorbala S, Ananthasubramaniam K, Armstrong IS, et al. Single photon emission computed tomography (SPECT) myocardial perfusion imaging guidelines: instrumentation, acquisition, processing, and interpretation. J Nucl Cardiol 2018; 25: 1784–​846.

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New technical developments in cardiac CT: Anatomy, fractional flow reserve (FFR), and machine learning Stephan Achenbach, Jonathan Leipsic, and James Min Contents

Introduction  145 Historical development  145 Areas for improvement  146 Prospectively ECG-​triggered axial acquisition  147 Single-​beat acquisition  147 Iterative reconstruction  148 Dual-​energy  CT  149 Functional assessment of coronary artery lesions  150 CT myocardial perfusion imaging  150 FFRCT  151 Recent learnings  153 Future opportunities  153 Quantitative coronary plaque evaluation  153 Radiomics and artificial intelligence in cardiac CT  154

Introduction Computed tomography (CT), in the context of cardiac imaging, faces numerous challenges. The heart is a complex, three-​dimensional organ, which moves very rapidly and has small dimensions. The coronary arteries, the main target of cardiac CT imaging, are especially difficult to visualize by any non-​invasive technique. All the same, technology progress has made the use of CT for cardiac and coronary diagnosis possible. For selected applications, including ruling out coronary artery stenoses in low-​risk individuals, CT has become a clinical tool [1, 2].

Historical development In order to be useful for cardiac imaging, several prerequisites must be fulfilled (see E Table 10.1). The first commercially available CT scanner that permitted visualization of the heart with high temporal and spatial resolution was the ‘electron beam tomography’ system introduced in the late 1980s. Instead of an X-​ray tube, which needs to rotate mechanically around the patient, it used an electron beam that was deflected by electromagnetic coils to sweep across semi-​circular targets arranged around the patient where the X-​rays were created. The radiation passed through the patient and attenuation was recorded by stationary detectors arranged on the opposite side. Temporal resolution was 100 ms, but slice thickness was limited to 1.5 or 3.0 mm, images were relatively noisy, and cost was high. The electron beam system is no longer available, but it demonstrated the utility of CT imaging for coronary artery calcium assessment and even early CT coronary angiography [3]‌. This prompted the development of cardiac applications for mechanical CT systems. Around the year 2000, the first multidetector row spiral (or ‘helical’) CT systems were introduced, permitting acquisition of up to four cross-​sections or slices with sub-​mm thickness simultaneously along with electrocardiographic (ECG) synchronized image reconstruction. A relatively low pitch (table feed) was used, so that every level of the heart was covered during the entire cardiac cycle by at least one of the four detectors (this acquisition mode is called ‘retrospectively ECG-​gated spiral acquisition’ and is still in use today). It allows all data acquired in systole to be discarded and images to be reconstructed based solely on X-​ray attenuation data acquired during phases of slow cardiac motion in diastole. Multirow acquisition was necessary to cover the complete

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Table 10.1  Prerequisites for cardiac imaging using CT Prerequisite

Achieved through

High spatial resolution

High-​resolution detector technology Thin slice thickness Relatively high radiation exposure (to reduce noise)

High temporal resolution

High rotation speed Half-​scan reconstruction algorithms Dual-​source  CT Multicycle reconstruction algorithms

Synchronization to heartbeat

Retrospectively ECG-​gated image reconstruction Prospectively ECG-​triggered image acquisition

volume of the heart within one breath-​hold, and with four-​slice systems, acquisition typically required 35 to 40 seconds. Imaging the coronary arteries was cumbersome, but possible [4, 5]. It was soon reported that low heart rates substantially improve image quality (since the diastolic phase of slow motion is prolonged) and short-​acting medication to control the heart rate has been recommended for cardiac CT ever since [6]‌. During subsequent years, the technology of CT evolved substantially. The main achievements were: faster rotation, which immediately translates to better temporal resolution; thinner slices, which improve spatial resolution; and stronger tubes, which are necessary to limit image noise, and are a prerequisite to achieve constant image quality while increasing temporal and spatial resolution. Furthermore, wider detectors were constructed, initially from 4 to 16 and 64 detector rows. A further increase of the number of simultaneously acquired slices was achieved through tubes that have two focal points, so that by rapidly alternating X-​ ray emission between the two focal points, the number of cross-​ sectional slices that are acquired is twice as high as the number of detector rows. Currently, the widest detectors have 320 rows. At a slice thickness of 0.5 mm, a scan volume of 16 cm can be covered, which is sufficient to cover the heart in ‘one sweep’, so that, unless a combination of data acquired during several cardiac cycles is used to improve temporal resolution, the entire heart can be imaged in one single diastolic phase [7]‌. This limits the potential for artefacts, permits short breath-​holds, and through the shorter data acquisition time, reduces the amount of contrast agent that is required to achieve intravascular enhancement during the acquisition. Another major hardware achievement is dual-​source CT. It combines two X-​ray tubes and two detectors arranged at an angle of approximately 90° [8]‌. Since X-​ray attenuation data acquired over an angle of approximately 180° are necessary to reconstruct one cross-​sectional image, dual-​source CT permits collection of the required data during a quarter rotation of the X-​ray gantry, while single-​source CT requires one-​half rotation. Dual-​source CT, therefore, improves temporal resolution by a factor of two. With a gantry rotation time of 0.24 s, the temporal resolution of each acquired slice is 66 ms (it does not exactly correspond to one-​quarter rotation time because the two tubes and detectors are not exactly aligned at a 90° angle). Another hardware innovation that uses two X-​ray tubes, but instead of combining two tubes

Table 10.2  Hardware improvements in cardiac CT and their effect on image quality Hardware improvement

Effect

Smaller detector elements

Higher spatial resolution

Thinner detector rows

Higher spatial resolution

More detector rows

Faster coverage of the volume of the heart (fewer heart beats), no influence on temporal resolution or spatial resolution

Faster gantry rotation

Higher temporal resolution

Dual-​source CT

Higher temporal resolution

Stereo X-​ray tubes

Smaller gantry size, improved spatial resolution

Stronger X-​ray tube

Lower image noise. Necessary to offset higher noise which would be introduced through thinner slices and faster rotation

arranged at an 90° angle in the x-​y plane, it has a stereo tube design, combining the two tubes in the z-​axis (approximately 7 cm apart). The stereo tube system allows for smaller gantry design, improved spatial resolution (isotropic 0.28 mm) and whole-​heart coverage of 14 cm. E Table 10.2 lists hardware advancements and their influence on image quality. Currently, four manufacturers provide high-​end CT systems capable of cardiac imaging. Gantry rotation time is 0.24 to 0.35 s, the number of detector rows ranges from 64 to 320, minimum slice thickness ranges from 0.5 to 0.625 mm, and X-​ray tube output from 72 to 120 kW (see E Table 10.3).

Areas for improvement At present, the main application of cardiac CT is coronary artery imaging. Without contrast agent, coronary artery calcification can be detected and quantified, an application that does not require technology to be stretched to its limits. After intravenous injection of contrast, CT permits visualization of the coronary artery lumen. In this context, the spatial and temporal resolution of current CT scanners is just about sufficient to achieve adequate image quality. However, in order to achieve stable image quality, the patient’s heart rate should be lowered to 60 beats/​min or less, motion artefacts can still be present, and the limited spatial resolution causes problems, e.g. with severely calcified coronary arteries, in the presence of coronary artery stents and in small vessels. Image noise can furthermore be a problem and in the interplay of temporal resolution, spatial resolution, and image noise, false-​positive findings can occur, which limit the specificity of coronary CT angiography, especially in difficult-​to-​image patients (patients with high heart rate, severe calcification, and high body weight) [9, 10]. A further issue is radiation exposure. Especially with spiral acquisition and retrospectively ECG-​gated image reconstruction, radiation exposure can be high and unless specific measures are taken to limit exposure, the effective dose can reach 25 mSv or more [11]. Numerous measures have been introduced to reduce dose, but they can increase image noise

Si n g l e- b eat ac qui si t i on Table 10.3  Comparison of technical properties of currently available high-​end cardiac CT systems GE Healthcare Revolution

Philips Healthcare iCT

Siemens Healthcare Somatom FORCE

Canon Aquilion One

Gantry rotation time

0.28 s

0.27 s

0.24 s

0.275 s

Minimum reconstructed slice width

0.625 mm

0.625

0.5 mm

0.5 mm

Number of rows

256

128 (256 slices)

2 × 192

320

Detector width

160 mm

80 mm

2 × 58 mm

160 mm

X-​ray tube output

120 kW

120 kW

2 × 120 kW

100 kW

Gantry aperture

80 cm

70 cm

78 cm

78 cm

(such as the use of lower tube current and lower tube voltage), or limit the options to obtain motion-​free images (such as the use of prospectively ECG-​triggered axial acquisition). The use of low and very low dose image acquisition protocols therefore need to be carefully balanced against the need to maintain appropriate image quality. A completely different aspect is the fact that the limitations of purely anatomic imaging of the coronary artery system are increasingly realized. The extent of ischaemia that a lesion produces is substantially more relevant than the mere anatomic degree of luminal stenosis. Pure anatomic imaging—​as provided, for example, by coronary CT angiography—​is therefore quite useful to rule out haemodynamically relevant coronary artery disease, but in order to identify lesions that require revascularization, information on inducible ischaemia is often desired. New technical developments—​both regarding hardware and especially software—​in cardiac CT address the problems outlined and it can be expected that they will increase the applicability of coronary CT angiography and cardiac CT in general.

The possibility to perform this data acquisition mode hinges on some hardware requirements: the detector must be of sufficient width so that the complete volume of the heart can be covered within a few steps. Typically, at least 64 slices must be acquired simultaneously (approximately 3 cm), so that the 12–​15-​cm scan range can be covered in 4 to 5 steps. Depending on heart rate, this amounts to 4 to 10 heart beats (in higher heart rates, images can only be acquired in every other cardiac cycle). Also, scanners must have a sufficiently fast rotation time to guarantee motion-​ free images in the prespecified cardiac phase. Especially when heart rate is well-​controlled (less than 60–​65 beats/​min), very high image quality can robustly be achieved with prospectively ECG-​ triggered axial acquisition and the associated radiation exposure is low (typically 1.0 to 3.5 mSv; see E Fig. 10.1). Prospectively ECG-​triggered axial acquisition, often termed ‘step-​and-​shoot’ acquisition, has become the standard scan mode for coronary CT angiography in many institutions.

Single-​beat acquisition Prospectively ECG-​triggered axial acquisition The traditional image acquisition mode in coronary CT angiograph has been retrospectively ECG-​gated spiral (or ‘helical’) acquisition. X-​ray data are acquired continuously throughout the cardiac cycle, and using the simultaneously recorded ECG, only X-​ray data during a specified time interval—​usually diastole—​are utilized for image reconstruction. Any desired time interval of the cardiac cycle can be used for image reconstruction, so that the ‘best time instant’ can systematically be searched to minimize motion artefact. Also, dynamic datasets can be reconstructed, which allow analysis of ventricular function. However, much of the acquired X-​ray data are not used for image reconstruction and hence, radiation exposure is relatively high. For this reason, all CT manufacturers have implemented prospectively ECG-​triggered axial acquisition modes. In this scan mode, no ‘spiral’ or ‘helical’ acquisition is performed. Instead, X-​ ray data are acquired without table movement, at a prespecified short time interval within the cardiac cycle, and then the X-​ray tube is switched off and the table moved to the next position [6]‌.

Acquisition of the entire cardiac data set in one single cardiac cycle is attractive because it eliminates ‘misalignment’ artefacts that can occur when the data set is pieced together from several cardiac cycles—​as typically done in retrospectively ECG-​gated spiral acquisition or prospectively ECG-​triggered axial acquisition. There are two options to acquire a data set of the entire heart within one cardiac cycle: If the detector is wide enough, a single prospectively ECG-​triggered axial acquisition may provide enough coverage to visualize the entire volume of the heart. This is typically possible with 256 to 320-​slice scanners [7]‌. Another option is high-​pitch spiral (or ‘helical’) acquisition, where the table is moved with such a high speed that the entire volume of the heart is covered during spiral acquisition in a period of about 200 ms [12]. This scan mode is well established and validated for dual-​source CT and, providing that heart rate is low and very stable, achieves good image quality at very low radiation exposure (see E Fig. 10.2). Single-​beat acquisitions are also attractive for myocardial perfusion studies since they provide a uniform data set of the complete left ventricle, with all data acquired at the same time interval after contrast injection.

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(b)

Fig. 10.1  Coronary CT angiography using

prospectively ECG-​triggered axial acquisition. In patients with low heart rates, high image quality can robustly be achieved. This example was acquired using 100 kV tube voltage, at an effective dose of 2.1 mSv, and shows a high-​grade stenosis of the proximal segment of the left anterior descending coronary artery, both in coronary CT angiography (a) and invasive coronary angiography (b). LCx: Left circumflex coronary artery, LAD: left anterior descending coronary artery.

Iterative reconstruction The conventional method of reconstructing images based on the acquired X-​ray attenuation data is called ‘filtered back projection’. This method does not make full use of the information in the X-​ ray data, but is computationally efficient, and therefore widely used in order to keep image reconstruction time acceptable in clinical practice. ‘Iterative reconstruction’ is a more elaborate image reconstruction method, which makes better use of the information in the X-​ray attenuation data, but requires substantially

(a)

longer times for reconstruction when compared to filtered back projection. However, with modern computers, processing power has increased so that iterative reconstruction methods can now be used clinically. While they alter the visual impression of the reconstructed image data, their substantial advantage is lower image noise (see E Fig. 10.3). Hence, they can be used in combination with low-​dose tube settings in order to maintain an acceptable contrast-​to-​noise ratio while substantially reducing radiation exposure [13, 14]. The potential of iterative reconstruction has not been fully explored yet, but it can be expected to be disseminated

(b)

Fig. 10.2  Single-​beat coronary CT angiography

using prospectively ECG-​triggered high-​pitch acquisition. Visualization of the left anterior descending coronary artery (a); left circumflex coronary artery (b); right coronary artery (c); and a three-​dimensional reconstruction of the heart and coronary arteries (d). With 100 kV tube voltage, the estimated effective dose was 0.84 mSv.

(c)

(d)

Dua l -e n e rg y   C T

Fig. 10.3  Visualization of the right coronary

artery in a low-​dose coronary CT angiography data set acquired at 80 kV (effective dose: 0.3 mSv). Comparison of image noise in conventional filtered back projection and iterative reconstruction. Based on the same raw data set, iterative reconstruction—​although at the cost of longer reconstruction times and visually altered image impression—​achieves lower image noise. It may therefore be suited to preserve image quality in low-​dose acquisitions.

widely very soon and to help keep radiation exposure of cardiac CT in an acceptable range.

Dual-​energy  CT The tissue-​specific absorption of X-​ray photons depends on their energy. Therefore, tissue type (even when its concentration is unknown) can be identified based on its relative absorption at different X-​ray energies. This effect is utilized in dual-​energy CT. Dual-​energy CT image acquisition can be performed using two different strategies, as energy separation can take place either at the side of the X-​ray source or at the side of the detector. The most useful approaches for dual-​energy scanning in cardiac imaging

(a)

(b)

are the ones with the lowest sensitivity to motion, which are fast kV-​switching (also called single-​source rapid-​switching), dual-​ source, and dual-​layer detector scanners. Using these techniques X-​ray photons with different peak energy levels are sent through the tissue or X-​ray photons separated by two-​layered detectors. Based on the differential absorption, specific materials—​such as iodine—​can be recognized. In cardiac imaging, dual-​energy CT is infrequently applied. Its use has been suggested to improve the assessment of iodine concentration in the myocardium (see Fig. 10.4), for example for perfusion imaging or late enhancement [15]. In peripheral vascular CT, dual-​energy CT has been used to improve the identification of iodine-​filled vessel lumen next to severely calcified plaque [16]. In cardiac and coronary artery imaging, this has not been fully explored, mainly since it would

(c)

Fig. 10.4  Colour-​coded dual-​energy imaging of the left ventricular myocardium. (a) Stress myocardial CT perfusion acquired by dual energy (100/​140 kV)

scanning. The iodine map indicates ischaemia with nearly zero iodine concentration (0.3 mg/​ml) in the basal septum (black arrow). The other myocardial territories show normal iodine concentration (4–​6 mg/​ml). (b) Rest myocardial CT perfusion, dual energy (100/​140 kV). The iodine map indicates normal iodine content (3–​4 mg/​ml). (c) Delayed scan, dual energy (100/​140 kV), monoenergetic image at 40 keV, with no apparent late enhancement. Courtesy of Dr. Ákos Varga-​Szemes, Medical University of South Carolina, Charleston, SC.

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not remove all negative effects that are created by calcium, such as aggravated motion artefacts.

Functional assessment of coronary artery lesions Relevant coronary stenoses can be ruled out very reliably if a coronary CT angiography data set shows a completely normal coronary artery lumen or very slight deposition of plaque. However, if luminal narrowing is present, CT does not provide for an accurate assessment of lesion severity. It is even less accurate for identifying lesions that cause ischaemia, since the degree of luminal narrowing and the effects on blood flow at rest and exercise do not correlate closely. All the same, ischaemia is the main reason to treat a coronary artery lesion and the inability to separate ‘functionally relevant’ (= ischaemia-​causing) lesions from stenoses that do not cause ischaemia has been an area of critique. In order to improve the ability of CT to identify ischaemia-​causing lesions, and also to possibly make lesion assessment more independent from image quality, several new developments are undertaken.

CT myocardial perfusion imaging The same data used for coronary computed tomography angiography (CCTA) acquisition can be reconstructed for visualization

of the myocardium and assessment of perfusion defects at rest or stress. During the administration of a pharmacological stress, CT myocardial perfusion images can be acquired using ‘static’ or ‘dynamic’ protocols which are compared with rest images to examine the presence and extent of ischaemia or scar [17]. ‘Static’ protocols are based on the acquisition of one ‘snapshot’ during the first-​pass inflow of iodine contrast, targeted at maximum myocardial enhancement for the best visualization of hypoattenuated (ischaemic) myocardium (see E Fig. 10.5) [18]. Dynamic perfusion involves the acquisition of multiple images during the myocardial contrast in and outflow and allows quantitative blood flow analysis. The benefit of myocardial blood flow analysis can is to detect low flow states during stress without the presence of relative perfusion defects, as may occur in balanced or microvascular ischaemia. The multicentre CORE320 study was the first and largest diagnostic accuracy study of combined CCTA and static CT myocardial perfusion for the diagnosis of ischaemia [19]. The gold standard was defined by ≥50% invasive angiography quantified stenosis with corresponding perfusion deficit on single photon emission computed tomography (SPECT). CCTA quantitative stenosis assessment achieved a C-​statistic of 0.84 on a per patient basis, which could be significantly improved when CT perfusion data was added (C-​statistic 0.87, P = 0.02). A more recent study evaluated 100 patients prospectively undergoing CCTA, static stress perfusion and invasive fractional flow reserve of all vessels with intermediate coronary stenoses using the newest generation CT scanners [20]. Binary

LAD (a)

(b)

(c)

(d)

(e)

(f)

Stress

Rest

Fig. 10.5  The upper panel shows a left anterior descending artery (LAD) with a severe non-​calcified plaque. Images of CT perfusion during stress (a–​c)

and rest (d–​f ). During adenosine stress, 3D fusion (a), short-​axis reconstruction (b) and polar plot display (c) demonstrate anterolateral hypo-​enhancement corresponding to the LAD lesion. (d–​f ) Rest CT perfusion, with same reconstructions as stress, demonstrate normal myocardial enhancement. Reproduced from van Rosendael AR, Dimitriu-​Leen AC, Bax JJ, Kroft LJ, Scholte A. One-​stop-​shop cardiac CT: Calcium score, angiography, and myocardial perfusion. J Nucl Cardiol. 2016 Oct;23(5):1176–​9 ((http://​creativecommons.org/​licenses/​by/​4.0/​).

F F R CT obstructive stenosis evaluation by CCTA yielded a sensitively of 98% and specificity of 54% for functionally significant coronary artery disease (CAD). When obstructive vessels were considered ‘positive’ or ‘negative’ given the presence or absence of corresponding downstream ischaemia, the sensitivity of the combined anatomical/​ functional approach stayed high (98%) while the specificity significantly improved to 83%. Similar results were observed on a per-​vessel bases; the sensitivity and specificity of CCTA were 98% and 76%, respectively, which was 91% and 94% for CCTA combined with CT perfusion imaging, respectively. Of importance, the mean effective dose was only 2.8 mSv for CCTA and 2.5 mSv for CT perfusion. This approach enables rule-​out of functional significant CAD with CCTA only, with selective rule-​ in of vessels with ischaemic obstructive stenosis by CT perfusion. Based on the severity of coronary symptoms, presence or absence of high-​risk anatomy, and extent of ischaemia this combined CT protocol has the potential to select patients that may benefit from revascularization, but this requires further prognostic study. A further addition of CT perfusion to CCTA may be in patients with prior revascularization, since coronary stents may cause blooming artefacts. Assessment of downstream perfusion with CT has been reported to significantly increase concordance rates with invasive angiography detected in-​stent restenosis [21]. Multiple studies have confirmed the ability of CT perfusion to diagnose functionally significant CAD. A meta-​analysis including 10 studies and approximately 750 patients of CCTA combined with CT perfusion and invasive FFR as reference standard reported the sensitivity ranging from 71 to 92% and specificity from 84% to 100% (1 study including 49 patients reported 47.8%) [22]. The CATCH-​2 (Cardiac CT in the treatment of acute chest pain 2 trail) evaluated the clinical utility of CT perfusion. Patient with a recent admission for acute chest pain but acute coronary syndrome ruled out were randomized to either CCTA or CCTA with CT perfusion. Following imaging, the patients within the CCTA + CT perfusion arm underwent 50% less invasive angiograms and revascularizations without increased major adverse events during 1.5 years of follow-​up [23]. Future studies should further define the optimal role of CT perfusion, but cardiac CT is emerging as an optimal approach for patients with anginal symptoms. A challenge of

CT perfusion is the susceptibility to motion and beam hardening artefacts that mimic true perfusion defects. Therefore, acquisition with the newest generation CT scanners, most important with the fastest gantry rotation times, gives the highest quality images and further technological improvements are anticipated.

FFRCT Fractional flow reserve CT (FFRCT) is a computationally derived non-​invasive tool using computational fluid dynamics for the derivation of a three-​dimensional pressure map (see E Fig. 10.6) allowing for the determination of pressure at any point in the coronary tree. Importantly, this model can be derived on the basis of a resting coronary CT without the administration of adenosine or a change in underlying CTA protocols [24–​28]. The methodology has been previously described extensively but in short, FFRCT relies on fundamental scientific principles of computational fluid dynamics enabled by an accurate anatomical model of the coronary arteries and myocardium, microcirculatory resistance and coronary branching, integration of physical laws that govern flow, as well as simulated hyperaemia intended to model the effects of adenosine. Finally, the Navier Stokes equations that solve for velocity, pressure and resistance for all Newtonian fluids can be applied to provide a three-​dimensional pressure map across the coronary tree. In addition, centralized off-​site computational analyses have created the potential to improve anatomical modelling through the developing of large data sets and the maturation of deep and machine learning. The initial studies focused on the diagnostic performance of FFRCT compared to the invasive gold standard of FFR. The most contemporary data is a subanalysis of the FFRCT AUC was 0.94, which was statistically higher than CT, SPECT, and positron emission tomography (PET). The FFRCT per-​vessel diagnostic accuracy was 87% with a sensitivity of 90% and a specificity of 86% [28]. SPECT per-​vessel sensitivity was only 42%. Importantly there were 13% of subjects whose image quality on CT was inadequate for FFRCT analysis highlighting the need to adhere to best practice cardiac CT acquisition protocol and ensure diagnostic quality coronary CT angiography.

Fig. 10.6  A 68-​year-​old male patient with

atypical chest pain underwent coronary CTA to exclude coronary artery disease is found to have a moderate (50–​69%) stenosis in the mid-​LAD. The lesion was uploaded for FFRCT analysis which documented borderline lesion-​specific ischaemia with an FFRCT value of 0.78.

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Regarding clinical utility, much of the initial investigations were focused on the potential of CTA/​FFRCT to help serve as a gate keeper to the invasive catheterization laboratory. This was tested in the PLATFORM Study in which two non-​overlapping cohorts of patients referred for invasive coronary angiography (ICA) were assigned to either undergo ICA or CTA/​FFRCT approach only undergoing ICA based on the results of the CTA and FFRCT. The CTA/​FFRCT arm resulted in significant enrichment of the catheterization lab with the burden of non-​obstructive disease reduced from 73 to 12% with stable obstructive disease and no events in the 61% of subjects in whom ICA was deferred through 12 months [29, 30]. The real-​world clinical utility of FFRCT is becoming increasingly established. The initial experience in the Assessing Diagnostic Value of Non-​invasive FFRCT in Coronary Care [30–​32] registry was recently published. In it the data it was noted that FFRCT modified treatment recommendation in two-​thirds of subjects as compared to CCTA alone, was associated with less negative ICA, predicted revascularization, and identified subjects at low risk of adverse events through 90 days. Longer term prognostic data is also beginning to accrue as well. Norgaard and colleagues recently presented data on nearly 700 subjects followed for a median of 2 years and highlighted the safety of deferral from revascularization of subjects with FFRCT>0.80, with equivalent risk of a >50% stenosis with FFRct >0.80 as an individual with a more modest anatomical stenosis [33]. As well, the investigators identified a heightened risk among those with an abnormal FFRCT who were treated with medical

REFINEMENT TECHNIQUE Big data and machine learning  automized anatomic segmentation  improved physiologic modeling  faster turn around time  Cloud based processing

therapy compared to those that were revascularized. To build on the initial experiences and to help fill the gap around randomized data two randomized trials have begun, one in the UK FORECAST and the other a larger international trial PRECISE, which will evaluate FFRct among symptomatic patients being referred for non-​invasive testing. Recently, there has been growing interest in using FFRCT to improve the efficient use of the invasive catheterization lab through increasing the PCI/​ICA ratio and providing guidance regarding revascularization strategies before the invasive angiogram [34]. The PCI/​ICA ratio has been shown to increase across a variety of healthcare systems with the greatest benefit being found in patients considered to have a higher pretest likelihood. The recently published SYNTAX III trial provided some insight into the potential of a CTA/​FFRCT strategy to guide revascularization decision-​making [34]. Heart teams were randomized to evaluate patients with complex CAD using either a coronary CTA/​FFRCT strategy or a conventional ICA strategy to guide revascularization decision-​making. The primary endpoint was a Cohen’s Kappa of 0.60 which was surpassed with an actual Kappa of 0.82 (95% CI 0.73–​0.91). This along with the SYNTAX II [35] data highlighting the strong correlation between non-​invasive functional syntax (CTA/​FFRCT) and invasive functional syntax (ICA/​ iFR) have helped solidify the hypothesis that a combined anatomical and physiological roadmap may prove helpful to the interventionalist in guiding and optimizing revascularization decision-​ making (see E Fig. 10.7).

% Myocardium

Plaque Intensity Map

Planner

More patient-specific physiological modeling e.g. including information on:  plaque burden and composition  area at risk  vessel volume to myocardial mass ratio

Improved CT image quality  CT technology  CT image quality control  standardized CT acquisition

Standardized interpretation criteria

CLINICAL TRIALS

0.80 0.84

Procedural planning  PCI and CABG

Fig. 10.7  The potential course for

ongoing technological development and scientific evaluation of FFRCT.

Randomized trials

 cost-efficiency, and safety relative to standard NI including CTP  “physiologic” diffuse CAD

New patient categories  a priori high risk?  known CAD

Numerical risk models  patient specific treatment

Qua n ti tati ve c orona ry pl aqu e eva luat i on

Recent learnings The clinical integration of FFRCT and ongoing work looking at atherosclerosis imaging with CT is introducing new opportunities to learn more about mechanisms of ischaemia and clinical risk. There is growing data linking previously described adverse plaque features shown to be associated with an increased risk of myocardial infarction (MI) with lesion-​specific ischaemia. Ahmadi et al recently built on these findings by noting that adverse bulky plaques with significant low attenuating components a feature seen in optical coherence tomography (OCT) adjudicated thin-​ cap fibroatheroma (TCFA) were associated with an increased likelihood of FFRCT positivity with the opposite also holding true in that FFRCT negative lesions are exceptionally unlikely to have a significant left atrial pressure (LAP) component [36].

Future opportunities In 2014, a computational interactive PCI planning tool was introduced aimed at idealizing the extracted lumen to allow for the recalculation of FFR simulating the post PCI state. A small prospective analysis of 44 subjects and 8 lesions was performed with baseline FFR and FFRct obtained prior to PCI in a fashion similar to other FFRCT accuracy studies but in addition FFRct was modelled following ‘virtual stenting’ and compared with invasively measured FFR post PCI. These data were highly provocative with an accuracy of 96% (sensitivity: 100%, specificity: 96% positive predictive value: 50%, and negative predictive value: 100%) [37]. While these data are very compelling there has been a lull in further scientific validation with further advancements in computational processing needed to enable its more routine evaluation. With the necessary computational capacity now available, a number of studies have begun to both look at the diagnostic performance of the planner tool as (a)

(b)

compared with post PCI FFR (PREDICT—​PREDICTing Post-​PCI in Substudy of NXT and PACIFIC Subjects) but also the extent to which the availability of such a tool would impact revascularization decision-​making and pressure wire usage (Benefits of Obtaining information for planning With noninvasive FFRCT prior to Invasive Evaluation: the BOWIE study).

Quantitative coronary plaque evaluation CCTA allows 3-​dimenstional high-​resolution visualization of the coronary tree. Current CCTA reporting guidelines recommend describing the most severe stenosis within the coronary tree combined with the prevalence of high-​risk plaque (defined by a lesion with ≥2 of low-​attenuation plaque, spotty calcification, or positive remodelling) [38]. Classification of patients’ risk by most severe stenosis provides good prognostic value and allows more intensive treatment plans with for more severe stenosis, including lifestyle intervention, medical therapy, or coronary revascularization [39]. However, the risk for future major cardiovascular events is more closely related to the total atherosclerotic burden than necessarily the most severe stenosis [40–​42]. Using multiple imaging modalities, a clear stepwise relationship exists between plaque burden and heightened event risk [40–​42]. A quantitative approach allows more comprehensive and detailed evaluation of the whole-​heart atherosclerotic burden and has therefore potential to more precisely inform a patient’s atherosclerotic risk. For instance, in addition to overall atherosclerotic burden, plaque composition, morphology, location, and volume have all shown prognostic value that cannot easily be integrated in a visual CCTA reports [43, 44]. Current semi-​automated software packages with automated lumen and vessel wall detection allow for plaque analysis of the entire coronary tree (see E Fig. 10.8) and have shown to accurately quantify atherosclerosis [45]. (c)

Fig. 10.8  (a) A non-​calcified plaque in the mid-​RCA segment, which causes intermediate stenosis (white arrow). (b) A total vessel plaque quantification. The red colour denotes low-​attenuation plaque burden. The corresponding invasive coronary angiography confirms the presence of plaque with intermediate stenosis (c).

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The ICONIC (Incident COroNary Syndromes Identified by Computed Tomography) evaluated the incremental role of quantitative plaque evaluation above visual stenosis assessment [46]. Independent from the volume of plaque, age, sex, and cardiovascular risk factors, plaque composed of fibro-​fatty or necrotic cores, high diffuseness of disease, and high cross-​sectional plaque burden, were among the atherosclerotic features independently predictive for the occurrence of acute coronary syndromes after CCTA. A further illustration of detailed plaque assessment is provided in E Figure 10.9. Histopathological evaluation of patients who died from sudden coronary death has demonstrated that ruptured coronary plaque had a large lipid-​laden core, with a thin inflamed fibrous cap [47]. CCTA defines plaque composition on plaque attenuation differences, where lower attenuation plaques correlate with ‘vulnerable’ lesions. There is an increasing interest in the quantification of low-​attenuation plaque, since multiple studies demonstrated that this type of plaque portents higher risk for future major events than calcified plaque [46, 48, 49]. Similarly, this type of plaque seems to be most susceptible to reduce in volume following statin therapy [50, 51]. As current, quantification of plaque is time consuming due to the semi-​automated nature of software packages. Future studies will examine the exact role of automated plaque analysis for individualized precise risk estimation. For diagnostic purposes in patients with symptoms suspect for myocardial ischaemia, a comprehensive atherosclerotic evaluation has shown to be more accurate in diagnosing haemodynamically significant CAD compared with stenosis assessment

(a)

LAD

[52, 53]. Atherosclerotic plaque increases vascular resistance and reduces the capability of a vessel to dilate and increase flow following adenosine infusion, all limiting coronary pressure and flow distal in the artery [54]. At a certain threshold, coronary flow will be to too low to perfuse the myocardial and the patient may experience anginal symptoms. The CREDENCE (Results from the Computed TomogRaphic Evaluation of Atherosclerotic DEtermiNants of Myocardial IsChEmia) will examine the diagnostic accuracy of a comprehensive quantitative coronary artery evaluation with CCTA for the diagnosis of invasively diagnosed ischaemia.

Radiomics and artificial intelligence in cardiac CT Beyond quantifying volumes of pathologies on radiological images, new analytic techniques such as radiomics try to enumerate the texture and shape of abnormalities [55]. Radiomics is a feature generative technique which quantify concepts such as heterogeneity with the use of mathematical formulas to numerically describe the composition and structure of pathologies [56]. Radiomics has been shown to identify napkin-​ring sign plaques which are precursors of rupture prone plaque. Using radiomics it is also possible to identify positron emission photography activity from conventional CT images [57], see E Figure 10.10. Radiomics has also be applied to the analysis of myocardium on CT and on MRI [58, 59] and for the analysis of perivascular

(c)

Vessel wall Lumen

(b)

LAP

SC

Fig. 10.9  (a) Quantitative analysis of high-​risk lesions before occurrence of STEMI. Multiplanar reconstruction of a left anterior descending artery

(LAD) lesion showing high risk atherosclerotic features. The cross-​sectional view demonstrated a large low-​attenuation area with a spotty calcification (b). The next day the patient developed ST-​s egment elevation myocardial infarction for which he underwent successful percutaneous coronary intervention. Source data from van Rosendael AR, Al’Aref SJ, Dwivedi A, Kim TS, Pena JM, Dunham PC, et al. Quantitative Evaluation of High-​Risk Coronary Plaque by Coronary CTA and Subsequent Acute Coronary Events. JACC Cardiovasc Imaging. 2019 Aug;12(8 Pt 1):1568–​71.

Re f e re n c e s

Fig. 10.10  Representative curved multiplanar and volume rendered CT images of three coronary plaques corresponding to specific invasive and

radionuclide imaging markers of plaque vulnerability. (a) A coronary lesion showing attenuation on intravascular ultrasound. (b) Depicts a coronary plaque which was positive for optical coherency tomography thin-​cap fibroatheroma. (c) A coronary lesion which showed positivity on NaF18-​positron emission tomography. The corresponding best radiomics parameters from CT images all outperformed the best conventional parameters to identify these pathologies [57].

fat tissue on CT [60]. The vast amount of information provided by radiomics can also be inputs to machine learning models to increase the capabilities of conventional CT imaging to identify vulnerable plaques [61]. Machine learning is a field of artificial intelligence gains new inferences by applying computer algorithms with the ability to learn from data without being explicitly programmed [62]. These algorithms have the potential to better model unique cases and therefore infer results specific

to each case rather than being generally true to the population. However vast amounts of data are needed for these methods. These methodologies—​ especially deep-​ learning—​ can also use the raw images as inputs rather than defining parameters from images beforehand as radiomic models do. These artificial intelligence techniques have been shown to improve automatic segmentation algorithms [63], and also to help clinical diagnosis of significant CAD [64].

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acute coronary events. JACC Cardiovasc Imaging 2019; 12(8 Pt 1): 1568–​71. 52. Driessen RS, Stuijfzand WJ, Raijmakers PG, et al. Effect of plaque burden and morphology on myocardial blood flow and fractional flow reserve. J Am Coll Cardiol 2018; 71: 499–​509. 53. Park HB, Heo R, B Oh, et al. Atherosclerotic plaque characteristics by CT angiography identify coronary lesions that cause ischemia: a direct comparison to fractional flow reserve. JACC Cardiovasc Imaging 2015; 8: 1–​10. 54. Ahmadi A, Stone GW, Leipsic J, et al. Association of coronary stenosis and plaque morphology with fractional flow reserve and outcomes. JAMA Cardiol 2016; 1: 350–​7. 55. Gillies RJ, Kinahan PE, Hricak H. Radiomics: images are more than pictures, they are data. Radiology 2016; 278: 563–​77. 56. Kolossvary M, Kellermayer M, Merkely B, Maurovich-​Horvat P. Cardiac computed tomography radiomics: a comprehensive review on radiomic techniques. J Thorac Imaging 2018; 33: 26–​34. 57. Kolossvary M, Park J, Bang JI, et al. Identification of invasive and radionuclide imaging markers of coronary plaque vulnerability using radiomic analysis of coronary computed tomography angiography. Eur Heart J Cardiovasc Imaging 2019; 20: 1250–​8. 58. Hinzpeter R, Wagner MW, Wurnig MC, Seifert B, Manka R, Alkadhi H. Texture analysis of acute myocardial infarction with CT: first experience study. PLoS One 2017; 12: e0186876. 59. Baessler B, Luecke C, Lurz J, et al. Cardiac MRI texture analysis of T1 and T2 maps in patients with infarct-​like acute myocarditis. Radiology 2018; 289: 357–​65. 60. Oikonomou EK, Williams MC, Kotanidis CP, et al. A novel machine learning-​derived radiotranscriptomic signature of perivascular fat improves cardiac risk prediction using coronary CT angiography. Eur Heart J 2019; 40: 3529–​43. 61. Kolossvary M, Karady J, Kikuchi Y, et al. Radiomics versus visual and histogram-​based assessment to identify atheromatous lesions at coronary CT angiography: an ex vivo study. Radiology 2019; 293: 89–​96. 62. Kolossvary M, De Cecco CN, Feuchtner G, Maurovich-​Horvat P. Advanced atherosclerosis imaging by CT: radiomics, machine learning and deep learning. J Cardiovasc Comput Tomogr 2019; 13: 274–​80. 63. Wolterink JM, van Hamersvelt RW, Viergever MA, Leiner T, Isgum I. Coronary artery centerline extraction in cardiac CT angiography using a CNN-​based orientation classifier. Med Image Anal 2019; 51:  46–​60. 64. van Hamersvelt RW, Zreik M, Voskuil M, Viergever MA, Isgum I, Leiner T. Deep learning analysis of left ventricular myocardium in CT angiographic intermediate-​degree coronary stenosis improves the diagnostic accuracy for identification of functionally significant stenosis. Eur Radiol 2019; 29: 2350–​9.

Disclosures: Jonathon Leipsic is a consultant for and holds stock options in Circl CVI and Heartflow.

157

SECTION 3

Valvular heart disease 11 Aortic valve stenosis 

161

Philippe Pibarot, Helmut Baumgartner, Marie-​Annick Clavel, Nancy Côté, and Stefan Orwat

12 Aortic valve regurgitation 

181

Julien Magne and Patrizio Lancellotti

13 Mitral valve stenosis 

191

Ferande Peters and Eric Brochet

14 Mitral valve regurgitation 

199

Daniel Rodríguez Muñoz, Kyriakos Yiangou, and José Luis Zamorano

15 Tricuspid and pulmonary valve disease 

211

Denisa Muraru and Elif Leyla Sade

16 Multiple and mixed valvular heart disease 

223

Philippe Unger and Madalina Garbi

17 Intraoperative transoesophageal echocardiography for valvular surgery  Joseph F. Maalouf and Hector I. Michelena

18 Valvular prostheses 

251

Luigi P. Badano and Denisa Muraru

19 Endocarditis 271 Daniel Rodríguez Muñoz and Álvaro Marco del Castillo

233

CHAPTER 11

Aortic valve stenosis Philippe Pibarot, Helmut Baumgartner, Marie-​Annick Clavel, Nancy Côté, and Stefan Orwat

Contents

Introduction  161 Assessment of aortic valve morphology  161

Aetiology of AS  161 Quantification of AS anatomic severity  163

Quantitation of AS haemodynamic severity  164

Echocardiographic parameters of AS haemodynamic severity  164 Transvalvular jet velocities and pressure gradients  164 Discordant grading of AS severity and role of multimodality imaging  170 Follow-​up interval and assessment of AS progression  171

Assessment of cardiac damage associated with AS  173 Left ventricular damage  173 Damage of other cardiac chambers  174

Integrative approach for the management of AS  175 Asymptomatic severe AS  175 Conclusion  177

Introduction Aortic valve stenosis (AS) is the most prevalent valvular heart disease and is increasingly diagnosed in high-​income countries due to an ageing population but also to more widely available diagnostic tools. The prevalence of AS is estimated at ~0.5% in the general population, ~2–​3% in the population over 65 years old [1]‌. This disease starts with mild fibrosis and calcification and thickening of the aortic valve leaflets without obstruction of blood flow, which is termed aortic sclerosis, and evolves over the years to severe calcification with impaired leaflet mobility and significant obstruction to blood flow, i.e. AS [2]. The clinical presentation includes the spectrum from asymptomatic patients with different grades (mild, moderate, severe) of AS severity to symptomatic patients with severe AS who may present with preserved or already depressed LV function and/​or reduced transvalvular flow. Accurate assessment of the AS anatomic and haemodynamic severity as well as the extent of cardiac damage associated with AS are crucial for the therapeutic management of patients with AS. Doppler-​ echocardiography is the method of choice providing a comprehensive non-​invasive diagnostic work-​up of these patients [3]. E Table 11.1 describes the recommended measures and findings to include in the standard echocardiography report. Other imaging modalities may provide important incremental information in patients with inconclusive results at echocardiography.

Assessment of aortic valve morphology The morphological assessment of the aortic valve is best performed in a parasternal short-​axis (PSAX) view. Additional information on aortic valve morphology and mobility can be obtained from the parasternal long-​axis (PLAX), the apical three-​chamber (A3C) and five-​chamber (A5C) views (E Table 11.1) [3]‌. Transoesophageal echocardiography (TOE) is superior to transthoracic echo in assessing aortic valve morphology. The assessment of aortic valve morphology is crucial and allows to identify the aetiology of AS and to quantify its anatomic severity.

Aetiology of AS Congenital AS Congenital AS is typically encountered in the form of a bicuspid aortic valve (E Fig. 11.1), although unicuspid, tricuspid, and quadricuspid forms are also encountered. Bicuspid aortic valve (BAV) is the most common congenital cardiac defect, affecting 0.5–​2% of the

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Table 11.1  Requirements for a standard echocardiographic report of a patient with aortic stenosis Items to include in the standard echocardiographic report for a patient with AS

Image and signal acquisition check-​list

1. Aetiology of aortic stenosis

2D/​3D assessment of the valve morphology in PLAX, PSAX, and apical views. TOE or MSCT if aetiology unclear with TTE

2. Morphology of the aortic valve and degree of valve calcification

Degree of leaflet thickening and calcification and assessment of leaflet mobility on 2D/​3D PLAX, PSAX, and apical views

3. Quantification of stenosis severity including the following measurements:   Peak jet velocity across the aortic valve   and   Mean gradient across the aortic valve   (Specify the echocardiographic window used to measure the velocity)   Stroke volume index (flow state)   Aortic valve area by continuity equation

Continuous wave Doppler performed from any imaging window that obtains the highest velocity, with the densest, most uniform continuous wave spectral profile Pulsed-​wave Doppler of laminar flow just proximal to flow acceleration. The modal velocity should be traced to measure the LVOT VTI LVOT diameter measured between aortic annulus and 5–​10 mm below annulus on videoclip and image frame providing the largest diameter

4. Left ventricular size and function:   LVEF   Diastolic dysfunction grade   Left mass index and relative wall thickness

AP4C and PA2C views optimized and focused on the LV for assessment of Biplane Simpson LV volumes. Pulsed-​wave Doppler of mitral flow at the tip of leaflets Doppler-​tissue imaging of lateral and medial mitral annulus Low PLAX view for measurement of LV dimensions

5. Concomitant valve diseases:   Aortic regurgitation   Mitral regurgitation   Tricuspid regurgitation

Multiwindow, multiplane colour Doppler imaging

6. Pulmonary artery pressure and right ventricular function

Continuous wave Doppler of TR velocity AP4C views optimized and focused on the RV

PLAX = parasternal long-​axis view; PSAX = parasternal short-​axis view, AP4C = apical 4-​chamber; AP2C = apical 2-​cahmber; RV = right ventricle; TR = tricuspid regurgitation; VTI = velocity time integral.

population and can be associated with other congenital lesions such as coarctation of the aorta [2, 4]. The most common variant is the fusion between the right and left coronary cusps (approximately 80%), which is also referred to as anterior-​posterior leaflet type (or Type 1), followed by a fusion of the right and the non-​ coronary cusps (approximately 19%), the right-​left leaflet type (or Type 2). Fusion between the left and non-​coronary cusps is rare (approximately 1%, Type 3) [4]‌. To establish the diagnosis, the valve must be visualized in the PSAX view in systole where

Normal aortic value

Rheumatic (non-calcific) AS

Tricuspid Calcific AS

True Bicuspid Calcific AS (Type 0)

Bicuspid Calcific AS with raphe (Type 1)

the orifice has a characteristic ‘fish mouthed’ appearance. Colour Doppler may also be useful to identify the numbers of commissures (two in bicuspid versus three in tricuspid). Frequently BAV features cusps of different size. During diastole, the raphe, which corresponds to an area of thickening at the site of the fused leaflets, can make the valve appear tricuspid. The distinction between a tricuspid and a BAV with a raphe is not always easy and TOE may help to differentiate between both entities. A symmetrical bicuspid without raphe is often referred to as a true BAV and has only two identifiable sinuses of Valsalva. Suggestive signs of a BAV are doming of the cusps in the PLAX view or an eccentric diastolic closure line in the M-​mode. The most frequent associated finding is a dilatation of the ascending aorta probably secondary to both abnormalities of the aortic media as well as proximal aortic flow and consequent wall stress. It can occur at the sinus level but also be restricted to the tubular part. The ascending aorta can be considered as dilated if >40 mm or 21 mm/​m2.

Rheumatic AS Rheumatic AS is a major health issue in low income countries. The valve is characterized by thickening predominantly at the edges of the cusps and commissural fusion (E Fig. 11.1). Frequently, concomitant aortic regurgitation is present and in most cases also the mitral valve is affected. Fig. 11.1  Aetiologies of AS transthoracic and transoesophageal

Calcific AS

AS = aortic stenosis.

Calcific AS is the most common form of AS observed in adult patients and is characterized by thickened and calcified cusps

echocardiography. Transthoracic and transoesophageal 2D short-​axis views of the aortic valve with different aetiologies of AS.

As ses sm en t of aorti c va lve morph ol o g y with reduced motion (E Fig. 11.1). Echocardiographically, echodense zones may correspond to zones of calcification. However, ultrasound is rather limited in differentiating between severe fibrosis and calcification and is with this regard inferior to other techniques such as multislice computed tomography (MSCT). This entity was formerly called degenerative AS it was thought to be a degenerative process [2]‌. However, it has been demonstrated that the underlying disease process is active with similarities to atherosclerosis and ultimately leads to valve calcification: calcific AS is therefore the more appropriate term. BAVs tend to calcify earlier than tricuspid valves. The distinction between bi-​and tricuspid valve may be difficult when extensive calcification is present.

Quantification of AS anatomic severity Calcification is the main culprit lesion of calcific AS although valvular fibrosis also contributes to the stenosis severity. It is thus important to quantitate the degree aortic valve calcification, which in fact represents in calcific AS the anatomic severity of AS and correlates strongly with the haemodynamic severity of AS. This is not the case in young adults with congenital or rheumatic AS where valve area primarily represents the severity of AS.

Semi-​quantitative assessment of aortic valve calcification by echocardiography Echocardiography can be used to semi-​quantitatively assess aortic valve calcification by description of echodense areas (E Table 11.1). For this purpose, the aortic valve is best viewed in

a PSAX view, although the PLAX and the A3C and A5C views are also helpful. The following classification has been proposed [5]‌: ◆ Mild calcification: isolated, small echodense spots ◆ Moderate calcification: multiple bigger spots ◆ Severe calcification: extensive thickening and calcification of all cusps (E Fig. 11.1). Although this classification has been shown to be of prognostic value, MSCT is superior in quantifying the extent of aortic valve calcification and has become the gold standard for this purpose (E Fig. 11.2).

Quantitation of aortic valve calcification by MSCT MSCT may be used to quantitate the amount of aortic valve calcification and the anatomic severity of AS. Non-​contrast MSCT scan with voltage of 120 mV and acquisition triggered at 70% to 80% of the R-​to-​R-​wave interval on the electrocardiograph (ECG) allows visualization of aortic valve calcification (AVC) and its quantitation using the modified Agatston method (E Fig. 11.2) [6]‌. It is the most frequently used method to calculate the AVC score. Areas with ≥4 adjacent pixels having a density >130 Hounsfield units are considered being calcification and are expressed as a score in Arbitrary Units (AU) using a semi-​automated software. Differentiating calcifications belonging to aortic valve versus to the LV outflow tract or the aortic root may sometimes be difficult. Nevertheless, MSCT quantitation of AVC allows correct identification of haemodynamically severe AS with a positive predictive value close to 90% in men and in women [7, 8]. Given that women reach severe AS with relatively less amount of calcification than

(a)

Aorta

LVOT

(b)

Fig. 11.2  Multislice non-​contrast CT to

quantitate aortic valve calcification in a man showing very severe valve calcification (a) and in a woman showing moderate calcification (b). Aorta

LVOT

AVC = aortic valve calcification; LVOT = LV outflow tract.

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men, sex-​specific thresholds must be used to identify severe AS: AVC ≥1,200 AU in women and AVC≥2,000 AU in men. These thresholds have been initially proposed by Clavel et al. [7] and subsequently validated in the context of a multicentre study [8]. In patients with a small aortic annulus (e.g. women) or with large aortic annulus (e.g. patients with bicuspid valve), the AVC may not adequately reflect the AS haemodynamic severity and the use of AVC density, i.e. AVC divided by the cross-​sectional area of the aortic annulus measured by echocardiography, has been proposed in these patients to identify severe AS with following sex-​specific thresholds: ≥300 AU/​cm2 in women and ≥500 AU/​cm2 in men. Anatomically severe AS defined with the use of AVC or AVC density thresholds presented here is strongly associated with the presence of haemodynamically severe AS, with faster progression of AS, and with worse clinical outcomes, including mortality and need for aortic valve replacement (AVR) [7, 9, 10]. The 2017 European Society of Cardiology (ESC) guidelines for the management of valvular heart disease recommend using the MSCT-​ derived AVC score for the evaluation of patients with low-​gradient AS in an integrated approach [11]. Severe AS may be considered very likely when AVC score ≥3,000 in men and ≥1,600 in women, likely when ≥2,000 and ≥1,200, and unlikely when 130 Hounsfield units/​ Does not account valvular fibrosis

–​

–​

Very likely: Women ≥1,600 Men ≥3,000 Likely: Women ≥1,200 Men ≥2,000 Unlikely: Women 71

51–​71

41–​51

30–​40

72

52–​72

41–​52

30–​40

21 mm with

300

400

500 Time (msec)

600

700

800

900

1000

collapse of 15 mmHg), while an IVC diameter of 50% represents a normal or low RAP (3 mmHg) [6]‌. The intermediate range representing 5–​10 mmHg has been simplified to 8 mmHg. This intermediate category can be adjusted based on additional parameters such as hepatic vein systolic:diastolic flow ratios as illustrated in E Table 35.4. There are a number of caveats and technical considerations when using the IVC. Guidelines provide a range of 3–​15 mmHg, which may significantly underestimate RAP in patients with severe disease wherein RAP can exceed 30 mmHg. When imaging the IVC, the measurement must be made between 1 and 3 cm from the orifice. Occasionally anatomic variations result in prominent valves at the ostium which can affect the IVC diameter. In addition, the IVC may transition from one plane to another giving it the appearance of collapse. Care must be taken to follow the track of the IVC plane with respiration. Additionally, studies have suggested that IVC size cut-​off should be indexed to BSA, with a cut-​off of 17 mm demonstrating greater discriminatory ability in a population of Asians, with a smaller average BSA [68]. Right atrial size and volume have also been studied as a measure of RAP. With increasing RA pressure, the RA dilates, however there may be cases of acute rises in RA pressure without significant dilatation and conditions of dilated RA without a very elevated RA pressure (e.g. chronic atrial fibrillation). A dilated RA in

Table 35.4  Estimation of right atrial pressures using echocardiography Mean RAP (mmHg)

IVC % collapse

Hepatic vein flows

0–​5

>50

Vs>Vd

5–​10

>50

Vs=Vd

10–​15

50% of systemic systolic blood pressure and/​ or PVR >1/​3 SVR). Echocardiography and MRI can both visualize atrial septal defects, however there are situations where one modality may be advantageous. Injection of agitated saline during echocardiography is a sensitive test to exclude atrial septal defects. Dynamic imaging when gadolinium is injected can also be used to detect the presence of an interatrial shunt on MRI. The relatively poorer spatial resolution of MRI limits visualization of small defects, given the standard slice thickness of 6–​8 mm. While thinner slices (4 mm) can be acquired, the lower signal to noise ratio could limit the image quality of thinner slices. Accordingly, it is challenging to identify a patent foramen ovale on MRI. Visualization of sinus venous defects using echocardiography can be challenging using standard imaging windows. The ability to acquire images in any plane with MRI has advantages when a sinus venosus defect is suspected (E Fig. 35.14).

C ondi ti on s as s o ciated w i th ri g ht ven tri cu l a r pat h ol o g y ASDs are typically visualized with axial-​and short-​axis stacks of SSFP images. The direction of flow can be determined using colour Doppler on echocardiography and in-​ plane phase contrast imaging on MRI. The haemodynamic significance of the defect can be assessed by the Qp:Qs or right-​sided chamber enlargement. Qp:Qs values of >1.5 are consistent with a haemodynamically significant shunt. Qp:Qs can be calculated using echo or MRI, with the MRI assessment viewed as more reliable. The echo assessment is based comparing the RV stroke volume (RVOT area × RVOT VTI) to the LV stroke volume (LVOT area × LVOT VTI). Although this method is technically feasible, its clinical utility is limited by error particularly in the RVOT and LVOT measurements used to calculate the outflow tract areas. The MRI assessment of Qp:Qs compares the RV stroke volume to the LV stroke volume. Stroke volumes are preferably obtained by direct measurement of forward flow through the main pulmonary artery and aorta using phase contrast sequences, however stroke volumes obtained from the volumetric assessment from short-​axis or long-​axis stacks can also be used provided there is no significant valvular regurgitation. Right-​sided chamber enlargement can be assessed by echocardiography or MRI, with MRI being viewed as the relative gold standard for volumetric quantification of right ventricular size. Diastolic septal flattening indicative of RV volume overload can be observed on echocardiography and MRI. Pulmonary venous anomalies can coexist with ASDs. Most frequently, the right upper pulmonary vein drains across a superior sinus venosus defect, however there could also be anomalous pulmonary venous connection with the right upper and/​or middle pulmonary veins connecting more cranially to the SVC. Transthoracic echocardiography has limited utility in delineating the pulmonary venous anatomy in adults. Transoesophageal echocardiography can identify the pulmonary venous anatomy, as

described in Section 3. Using MRI, pulmonary venous anatomy can be assessed with black blood sequences or MRA. Assessment of PH can be performed non-​invasively on echocardiography or invasively with heart catheterization. Although techniques for estimation of pulmonary pressures and PVRs using MRI are emerging, the utility of MRI to measure pulmonary pressures and pulmonary vascular disease remains limited. Finally, both methods can delineate the size of the defect and assess for feasibility for percutaneous closure, though three-​ dimensional echocardiography is more commonly used for this indication—​particularly for secundum defects (E Fig. 35.15). Transoesophageal or intracardiac echocardiography are routinely used to guide closure of these defects. E Table 35.5 summarizes the utility of each modality in assessment of interatrial shunts.

Tricuspid regurgitation Right ventricular dilation could be the cause or consequence of TR. In evaluation for the mechanism of TR, the spatial and temporal resolution of echocardiography provides advantages over MRI in investigating the mechanism of the TR, which is often critical in determining surgical approach, when indicated. The right atrium should be assessed as well, as a dilated right atrium, particularly in the setting of permanent atrial fibrillation, can contribute to TR severity. The thin tricuspid leaflets are often not well visualized on MRI. Measurement of the tricuspid valve annulus at end diastole in the four-​chamber view can be performed on both echocardiography and MRI, although normal values are less well defined using MRI. From a management perspective, surveillance of RV size and function with echocardiography or MRI can identify progressive changes in the right ventricle. In patients with mildly symptomatic or asymptomatic primary TR, progressive RV dilation or dysfunction is a Class 2a indication for valve intervention [88].

(a)

(b)

Fig. 35.15  (a) TTE image depicting secundum ASD with left-​to-​right shunting on colour Doppler (b) 3D TEE of the same patient further depicting the large secundum ASD (measuring 17 × 25 mm) used to guide percutaneous ASD closure.

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Table 35.5  Comparison of the utility of echocardiography and MRI in the assessment of atrial septal defects Transthoracic Echocardiography

MRI

Visualization of the shunt

Can visualize small shunts Off-​axis imaging for sinus venosus defects

Visualization of sinus venosus defects Limited utility in small or fenestrated shunts

Evaluation of haemodynamic significance

Visualization of RA and RV dilation Measurement of Qp:Qs challenging due to measurement errors

Non-​invasive reference standard for RV volumes Reliable assessment of Qp:Qs

Estimation of pulmonary pressures

Possible

Limited value

Evaluation for associated defects (i.e. PAPVR)

Limited visualization of pulmonary veins on TTE

Pulmonary veins can be visualized using axial stacks of black blood images or MRA

Pulmonary regurgitation Significant pulmonary regurgitation is most commonly encountered as a sequalae of repaired congenital pulmonary stenosis with pulmonary valvotomy or repaired tetralogy of Fallot. Quantification of the degree of pulmonary regurgitation is possible with both echocardiography and MRI and is fully described in Section 3. The measurement of RV size, RV function, and RVSP informs whether significant pulmonary regurgitation requires intervention in asymptomatic patients. In asymptomatic patients with repaired tetralogy of Fallot, PVR is recommended as a Class 2a recommendation if two of the following five parameters are present: (1) More than mild RV or LV dysfunction; (2) RV dilation by MRI (RVEDVi >160 ml/​m2 or RVESVi >80 ml/​m2); (3) relative RV dilation defined as RVEDV >2 times the LVEDV; (4) RVSP >2/​3rds of the systemic pressure; and (5) objective decline in exercise tolerance as measured by cardiopulmonary exercise testing [89]. Four of these five criteria are based on imaging parameters, requiring both echocardiography and MRI. The volume-​related criterion is based on multiple studies focused on identifying cut-​ offs of RV dimensions beyond which valve intervention does not result in RV remodelling [62, 90–​94]. Findings from a cohort of 339 patients with tetralogy of Fallot identified the optimal time for detection of progression was 3 years [95], forming the basis of the recommendations to perform serial exams at 3 year intervals. In patients with RVEDVI >150 ml/​m2 or a progressive increase in RVEDVi (>25 ml/​m2 from previous) or progressive decline in RVEF (RVEF 2.8 m/​sec has been identified, the next step is to look at the pulmonic valve and possibly the pulmonary artery bifurcation to rule-​out any pulmonary stenosis. The pulmonary valve can be seen from the parasternal RV outflow tract view. In a normal pulmonic valve, the cusps appear mobile and open in a parallel position to the pulmonary artery wall.

Pulmonic stenosis In pulmonary stenosis the leaflets will appear ‘doming’ in systole with restricted mobility. By colour Doppler, there is evidence of pulmonary stenosis (PS) as accelerated flow beyond the stenotic pulmonary valve (PV). Echocardiography has a significant role in timing and identifying candidates for transcatheter pulmonic valve intervention. The size of the pulmonary annulus should be measured, either on echocardiography or CT to determine if the valve size is suitable for available transcatheter pulmonic valves and to determine the optimize size the balloon if balloon valvotomy is considered. Indications for intervention include asymptomatic patients with and peak gradient >60 mmHg and symptomatic patients and peak gradient >50 mmHg. Typically, chronic severe RV pressure overload is characterized by a hypertrophied RV wall and a systolic D-​shape deformation of the ventricular septum as seen from parasternal short-​axis projections at mid-​LV level. As a result, the short-​axis of the LV will appear circular in diastole but during systole will assume an oval shape with systolic flattening of the ventricular septum. Thus, the LV short-​axis will cease to be circular and instead present with two asymmetric diameters perpendicular to each other during systole; the major axis and the minor axis. The ratio of major over minor axis is called the eccentricity index (E Fig. 35.16a, b). The greater the eccentricity index the greater the severity of elevated RV systolic pressure. In addition to those anatomic changes, the RV may become hypokinetic with reduced systolic function, visualized from numerous imaging planes, using quantitative measures presented above. This overall RV hypokinesis separates a pressure loaded RV from a volume loaded RV, where the RV will retain its preserved systolic function until very late in the disease process.

Pulmonary embolism In pulmonary embolism (PE), the echocardiographic signs are often indirect and reflected primarily by the RV size and function.

C ondi ti on s as s o ciated w i th ri g ht ven tri cu l a r pat h ol o g y

(a)

(b)

Fig. 35.16  (a, b) The LV appears

(c)

(d)

The greater the RV with a poor function may be related to an adverse outcome. A distinctive pattern of mid-​free-​wall hypokinesis with a normal or hyperdynamic RV apex, the McConnell sign, has been described in patients with acute pulmonary embolism (PE), but this wall motion pattern is not specific and has also been seen in some patients with RV infarction or acute hypoxemia and acidosis (E Fig. 35.16c). Acute PE may lead to RV pressure overload and dysfunction. TTE findings include: ◆ RV dilatation ◆ free-​wall hypokinesis ◆ paradoxical interventricular septal motion ◆ tricuspid regurgitation ◆ raised pulmonary pressure ◆ dilated non-​collapsing IVC ◆ LV diastolic abnormalities Direct visualization of right heart thrombus using echocardiography is uncommon, with thrombus seen in less than 4% of suspected PE patients and therefore its main role in these patients is in identifying the indirect signs of acute pressure overload. The direct visualization of mobile thrombi within the right heart is rare but highly diagnostic when detected and is associated with increased mortality. With transthoracic echocardiography thrombus is seen most commonly in patients with suspected PE within the proximal IVC or right atrium and

circular in diastole (left) while in RV pressure overload (right) the LV appears ‘deformed’ with a major and a minor axis that forms the eccentricity index. (c) The McConnell sign. This is characterized by a regional RV dysfunction with mid-​free-​wall hypokinesia while the apical motion is preserved (arrow). (d) RV inflow tract view with a highly mobile thrombus in the RA.

appear as mobile, often worm-​like masses, which if unattached appear to swirl around within the associated chamber, usually in the atria (E Fig. 35.16d).

Chronic pulmonary hypertension PH is presently defined as an increase in mean pulmonary arterial pressure to ≥25 mmHg at rest as assessed by right heart catheterization. It is classification includes five categories. The most common category is the post-​capillary PH, that of secondary PH due to left heart disease (Group 2), an elevated PA wedge pressure (≥15 mmHg), and a normal PVR of ≤3 WU [14]. Hence a comprehensive echocardiographic study with measures of elevation in left-​ventricular systolic and diastolic function, left-​sided valvular disease, and left atrial volume must be performed in all cases. Precapillary PH is characterized by a mean PAP ≥25 mmHg, an elevated PVR of ≥3 WU, and a low PA wedge pressure of ≤15 mmHg [14]. Patients with precapillary PH have generally more pronounced signs of RV pressure overload with a normal left-​sided E/​e’ ratio, a very dilated IVC (usually >20 mm), a very dilated RV cavity with the RV apex dominating the apical four-​chamber view, an eccentricity index >1.2, and notching of the RVOT pulsed Doppler envelope, suggesting high PVR and a prominent reflected wave [97]. Echocardiographic parameters that provide prognostic information in the past had focused on indirect signs of RV failure (RA dilatation and pericardial effusion) [69], but more recently, direct measures of RV systolic function such as TAPSE and RV free

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wall strain have predicted outcomes [61, 75]. It should be noted that one cannot simply rely on TAPSE or S’ to assess RV systolic function in PAH, as the RV may be significantly impaired with focal preservation of the basal free wall segment only.

Cardiomyopathic conditions associated with RV pathology Arrhythmogenic cardiomyopathy Arrhythmogenic cardiomyopathy (AC, formerly termed arrhythmogenic ventricular cardiomyopathy) is a rare yet important diagnosis given its associated risk of sudden cardiac death and autosomal dominant inheritance pattern. Echocardiographic and MRI-​derived parameters are components of the Modified Task Force Criteria for AC [15] (E Table 35.6). The positive predictive value of the Modified MRI-​derived criteria is 55% [64]. There are five important aspects of the criteria. Firstly, patients need to have RV wall motion abnormalities plus abnormalities in either RV size or function to fulfil the criteria. The presence of RV dilation or global RV dysfunction on its own does not fulfil the criteria. Secondly, the imaging parameters do not make the diagnosis; tissue characterization (myocardial biopsy), repolarization abnormalities, depolarization/​conduction abnormalities, arrhythmias, and family history must also be assessed. A definite diagnosis includes two major or one major and two minor criteria or four minor criteria from different categories. Thirdly, the cut-​offs for RV dilation differ from the normative values used in non-​AC assessments. Fourthly, although the presence of fibro-​fatty infiltration is often assessed in patients with suspected AC, it is a non-​specific finding and is not included in the criteria for AC [98]. Lastly, right ventricular LGE is not a component of the criteria however can be identified in patients with AC. RV LGE has been reported in up to 88% of patients with AVRC [99, 100]. Approximately 50% of cases also involve in the LV, highlighting the need to comprehensively evaluate the LV, including tissue characterization with LGE. LGE can be identified in the basal inferolateral wall of the LV in patients with AC [64]. The multimodality imaging approach to AC is outlined in the EACVI expert consensus statement on AC [98]. The echocardiographic assessment for AC includes a comprehensive

echocardiogram, including the required RVOT measurements, multiple views of the RV to identify regional wall motion abnormalities (E Fig. 35.17a, b) and FAC to assess the Modified Task Force criteria. There is an emerging role for 3D TTE to identify regional wall motion abnormalities and assess RV size and function in AC, albeit cut-​offs for abnormal values specific to AC are not well defined [98]. The MRI assessment for AC includes an axial stack of double inversion TSE/​FSE with and without fat suppression, axial, and short-​axis stacks of SSFP cines covering the entire right ventricle, RV inflow-​outflow SSFP cine and RVOT SSFP cine [8]‌. Close attention should be paid to identify any regional wall motion abnormalities on each view. The ‘accordion sign’ to describe focal ‘crinkling’ of the myocardium has been described in patients with AC (E Figure 35.17c, d) [101, 102]. Recognition of normal variants is important to avoid overdiagnosis of regional wall motion abnormalities (E Fig. 35.10). Delayed gadolinium imaging is performed including axial stack, short-​axis stack, and four-​ chamber and vertical two-​chamber slices [8].

Athlete’s heart As in many other conditions, the focus of cardiac remodelling was on the left heart with criteria established to help assist in the differentiation between normal and pathologic [103]. Only more recently have investigators looked rightward to study anatomic and physiologic changes in the athlete. This distinction is particularly important when different remodelling patterns exist between strength training and endurance-​trained athletes, with evidence of RV chamber dilatation by RV basal diameter, as well as indexed RV EDV in the endurance-​trained athletes (ETAs), particularly with increased duration of training [104]. The evidence for increased wall thickness is less robust, with a trend found in strength training athletes (STAs). From Ohm’s law, the relationship between pressure and flow and resistance, greater flow should yield a higher pressure. Accordingly, the ETAs also had evidence of increased resting PAP with a 2SD cut-​off of 40 mmHg. Interestingly, both ETAs and particularly STAs demonstrate lower free wall strain, but have increased Isovolumetric Ventricular acceleration and no difference in B-​type natriuretic peptide (BNP) levels, suggesting that this reduced strain may

Table 35.6  Imaging-​related criteria for AC Major

Minor

Echocardiographic

Regional RV akinesis, dyskinesis or aneurysm, AND 1 of the following (end diastole) ◆​  PLAX RVOT  ≥2 mm (≥19  mm/​m2) ◆​  PSAX RVOT  ≥36 mm (≥21  mm/​m2) ◆​  Fractional area change ≤33%

Echocardiographic Regional RV akinesis or dyskinesis, AND 1 of the following (end diastole) ◆​  PLAX RVOT ≥29 to 4.2 cm

  RVOT parasternal long-​axis   diameter

>3.3 cm

Function   TAPSE

2.1 cm

  IVC collapse with sniff

35–​40 mmHg

MRI parameter

Abnormal cut-​off

  RA volume (biplane)

>126 ml/​m2

  RV end-​diastolic volume

Females >112 ml/​m2: Males >121 ml/​m2

  RV end-​systolic volume

Females >52 ml/​m2: Males >59 ml/​m2

  RVEF

Females 100 exams/​year to maintain competence [10, 11]. The best echo machine in the laboratory should be used to obtain adequate images. Secondary harmonic imaging is necessary [12]. A nurse is present to adapt the infusion doses, monitor the blood pressure and inject an antidote if necessary (beta-​blocker with DSE or aminophylline with dipyridamole test). Pulse oximetry and a resuscitation equipment including defibrillator, drugs, and oxygen delivery should be available. The test can be performed in outpatients but in an hospital with an intensive care unit [13]. A full digital stress echo package is necessary.

Acquisition of images Most tests are obtained using two-​ dimensional transthoracic echocardiography. Images are triggered at peak R wave which requires a good quality electrocardiograph (ECG) and an appropriate amplitude of R waves. Complete cardiac cycles are obtained. It is preferable to record the previous cycle or to select the best loop among several recorded cycles. The protocol of acquisition is predefined: number of views, number of steps, tissue Doppler images, or contrast use. Interpretation should be available on stations with possible slowing of the images. A complete quantification package is also needed. Most patients in whom viability is tested are treated with a beta-​blocker. Long withdrawal is not recommended. If resting tachycardia is present or if heart rate increases too rapidly, the eventual hibernating myocardium can be already ischaemic at the onset of the test.

Recording Classically, five different views are recorded (parasternal long-​ and short-​axis views, apical four-​chamber, two-​chamber, and long-​axis views) at rest, low-​dose, peak dose of dobutamine and recovery. Usually, the duration of each step is 3 minutes, but can sometimes be shortened to 2 minutes or lengthened to 5 minutes. The first low dose is frequently 10 mcg/​kg/​min but can be decreased to 5 mcg/​kg/​min or even 2.5 mcg/​kg/​min to avoid a too rapid increase in heart rate, especially if a beta-​blocker has been withdrawn. Incremental doses are 20, 30, and 40 mcg/​kg/​ min with the eventual addition of atropine from 0.25 mg to 1 mg to obtain the target heart rate when both viability and inducible ischaemia are evaluated [14]. Larger doses of dobutamine (50 mcg/​kg/​min) or atropine (1.5–​2 mg) are rarely used. Atropine can be added earlier than at peak dobutamine dose to obtain a more gradual increase in heart rate. With a dedicated table, a low charge of exercise can be added to completely eliminate the vagal tone.

Table 36.1  Semiology of stress echocardiography Rest

Stress

Myocardial state

Normokinesis

Hyperkinesis

Normal

Normokinesis

Hypokinesis

Ischaemia

Hypokinesis

Normokinesis

Viability, C Reserve

Akinesis

Biphasic response

Viability, at jeopardy

Akinesis

Akinesis

Scar

No contractile material

Infusion of a beta-​blocker (intravenous metoprolol) is systematic in some laboratories or performed only in case of side effect, too low decrease in heart rate or arrhythmias.

Interpretation Echocardiography permits the evaluation of endocardial motion, but more importantly myocardial thickening and its timing, with eventual delayed thickening or post-​systolic thickening (E Table 36.1). Hypokinesis at rest implies the presence of some viability. Akinesis is present not only in regions with transmural necrosis but as soon as >20% of myocardial thickness is necrotic [15]. There are several responses during DSE: ◆ Sustained improvement of myocardial thickening, not delayed at low to peak dobutamine doses. This implies contractile reserve with preserved or recovered flow reserve, without induced myocardial ischaemia. In acute coronary syndrome, this response is seen in stunned myocardium. In chronic conditions, the response corresponds to contractile reserve of the preserved subepicardial layer (E Fig. 36.2). ◆ Biphasic: akinetic regions showing improvement of thickening at low dose of dobutamine followed by deterioration at higher doses. This is observed in viable segments perfused by a coronary artery with reduced flow reserve [16, 17]. The contractile reserve is due to the inotropic effect of dobutamine without a significant increase in heart rate; the deterioration develops at higher heart rate when myocardial oxygen demand has increased to a level that cannot be supplied by the stenotic vessel. The myocardium is at jeopardy. Rapid revascularization is indicated to obtain functional recovery [18, 19] (E Fig. 36.3). ◆ Contractile reserve limited to the border zone of a necrotic region, approximately 1 cm. This type of response should not be considered as myocardial viability when the improvement is only seen in tethered regions. ◆ Worsening of thickening in hypokinetic segments, implying inducible ischaemia. ◆ Asynergy developed in adjacent segments perfused by the same artery as the akinetic segment, suggesting a residual stenosis of this artery. ◆ Akinesis without change: this is the sign of necrosis, but could also be seen if the myocardium is severely

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Fig. 36.2  Sustained improvement

with dobutamine stress echocardiography: end-​systolic stop-​frame images in the apical two-​chamber view: top left: severe hypokinesis of both the anterior and the inferior wall; top right: moderate contractile reserve; bottom left: intense contractile reserve of anterior and inferior walls

hibernating with loss of contractile material. This can also be observed if resting heart rate is high or if the increase in heart rate is too rapid, in particular after beta-​blocker withdrawal. ◆ Additional ischaemic segments during the recovery period after beta-​blocker infusion: this may relate to stimulation of alpha 1 receptors leading to epicardial vasoconstriction.

Fig. 36.3  Biphasic response: end-​

systolic stop-​frame images in the apical long-​axis view; top left: severe hypokinesis of the anteroseptal segment; top right: improved contractility; bottom left: deterioration of systolic contraction

◆ Asynergy in another coronary territory, indicating multivessel coronary artery disease. When the coronary anatomy is known, with a severely stenotic coronary artery, it is indicated to use a very low dose of dobutamine (2.5 mcg/​kg/​min during a longer step of 5 min) to recruit the potential flow and contractile reserve before the induction of myocardial ischaemia. The test can be performed under

Asses sm en t of m yo ca rdia l via b i l i t y b y echo ca rdi o g r a ph y beta-​blocker therapy with incremental doses to obtain at least a small increase in heart rate (10 beats/​min). In most laboratories, the interpretation remains qualitative and is dependent of the experience of the operator. Even in experienced hands, there is a significant interobserver variability.

Other stress modalities DSE is the most frequently used modality, but other stress modalities have been evaluated. Low-​dose dipyridamole (0.28 mg/​ kg) can induce endogenous adenosine accumulation. The stimulation of adenosine receptors can induce coronary vasodilation, recruiting flow reserve and in turn improving contraction [20]. Low-​ dose dipyridamole can be combined to low-​ dose dobutamine [21]. High doses of dipyridamole with the addition of atropine can provoke myocardial ischaemia and detect a biphasic response. Levosimendan can increase contractility without increasing myocardial oxygen demand and induces vasodilation. A study suggests that levosimendan stress echo provides similar specificity, around 80% but shows a better sensitivity (75% for a sensitivity of 59% with DSE) [22]. Exercise induces catecholamine stimulation. A low charge of exercise can induce contractile reserve and detect viability [23] but the disappearance of the vagal tone may lead to a rapid increase in heart rate masking the contractile reserve. Of note, a complete exercise test has been shown to identify a biphasic response and detect jeopardized myocardium [24].

Contrast echocardiography Left ventricular opacification The quality of images is essential for a correct interpretation and in turn improves the diagnostic accuracy. The intravenous infusion of a contrast agent with second harmonic imaging can enhance through LV opacification a better endocardial definition and provides a better interobserver reproducibility [25]. Some laboratories use contrast in most cases. LV opacification is recommended when at least two myocardial segments are not correctly visualized in basal conditions (most frequently the anterior wall in the two-​chamber view or the lateral wall in the four-​chamber view).[26]

Myocardial contrast echocardiography Contrast agents consist in microbubbles remaining in the intravascular space. Microvascular integrity is a prerequisite for myocardial viability. The presence of microbubbles in a myocardial segment implies the presence of preserved microvasculature. Several modalities have been used. The usual method consists in a continuous intravenous infusion of the contrast agent, a flash with high mechanical index which destroys the microbubbles and the observation and quantitation of reopacification of the myocardial segments. The signal intensity corresponds to the capillary blood volume; the speed of contrast replenishment denotes myocardial blood velocity. The product of myocardial

blood volume and red cell velocity corresponds to myocardial blood flow [27]. Absence of myocardial opacification denotes the absence of microvascular integrity and thus absence of contractile reserve (E Fig. 36.1). When both signs are lacking, there will be no functional recovery. Viability is present when myocardium is fully replenished with homogenous, normal contrast intensity [28]. The observation should be done during 10 to 15 cardiac cycles [29]. The utility of myocardial contrast echocardiography is more powerful when combined to the presence or absence of contractile reserve [30, 31].

Coronary flow reserve Harmonic imaging and high frequency probes enable the non-​invasive assessment of coronary flow and coronary velocity reserve by transthoracic Doppler echocardiography. Coronary flow reserve examines complete function of the coronary circulation from the epicardial arteries to the microcirculation [32]. It is relatively easy to record coronary flow in the left anterior descending artery, but it is more difficult in the right coronary and circumflex arteries. Normal coronary flow is biphasic with a predominance of the diastolic component. After the recording in basal conditions, coronary velocity is measured during intravenous infusion of adenosine (140 mcg/​ kg/​min over 5 minutes) which induces maximal coronary vasodilation and in turn increase in coronary velocity. Dividing the peak and basal velocities defines coronary reserve related to the severity of coronary artery stenosis. This technique is not frequently performed but can be useful in the presence of moderate coronary stenosis in addition to the analysis of regional contractile reserve.

3D echocardiography 3D echocardiography can provide the three apical views of the same cardiac cycle which can be useful for the assessment of regional contractility and contractile reserve. Real-​time 3D echo can reconstitute a series of short-​axis views from basal to apical left ventricle during the same cardiac cycle. The increase in temporal resolution of the most recent machines will permit a better analysis at higher heart rates. 3D contrast low-​dose dobutamine permits LV enhancement and analysis of myocardial perfusion. The technique has been shown to be useful and effective [33].

Myocardial deformation The major drawback of echocardiography is the qualitative interpretation and in turn a significant variability in the presence of subtle changes. Parameters of myocardial deformation—​strain and strain rate—​have recently be used to provide more quantitative parameters. Strain consists in the percentage of deformation and strain rate the rate of deformation of a specific segment. The

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parameters can be obtained by tissue Doppler imaging and preferably by the speckle tracking method which has the advantages of being independent of the angle of insonation and of providing a better signal/​noise ratio [34].

decreasing the specificity [36]. The best cut-​ off value for predicting recovery was a dobutamine induced increase of strain rate of 0.25/​s.

Tissue Doppler imaging

The speckle tracking method can evaluate longitudinal, circumferential, and radial deformation and rate of deformation with a good reproducibility. Hoffmann et al. have demonstrated that an increase of > 0.23/​s, as compared to 18FDG, identified viable myocardium with a sensitivity of 83% and a specificity of 84% [37]. Bansai et al. showed that longitudinal and circumferential strain during low-​dose dobutamine predicted functional recovery after revascularization with a sensitivity of 83% and a specificity of 93% [38].

Experimental studies have shown that the method can identify myocardial viability. Clinical studies are rather scarce (E Fig. 36.4). Hoffmann et al. have found a good concordance with perfusion imaging and demonstrated that strain rate measurement allows improved assessment of myocardial viability in patients with depressed LV function [35]. Hanekom et al. have studied several parameters to predict functional recovery after revascularization. The addition of strain rate to the conventional wall motion score index improved the sensitivity from 73% to 83% without

Speckle tracking

Fig. 36.4  Example of strain rate curves with dobutamine showing improvement in the anterior and inferior walls at low dose (top right) and deterioration at peak dose (bottom left).

Asses sm en t of m yo ca rdia l via b i l i t y b y echo ca rdi o g r a ph y Longitudinal myocardial fibres are predominant in the subendocardial layer. Therefore, a layer specific analysis of strain and strain rate can be more predictive than a full thickness assessment. A study has shown similar sensitivity, specifity, and accuracy as single photon emission computed tomography (SPECT) without the use of a pharmacological test [39]. Global longitudinal strain is probably the most robust parameter [40]. Compared with contrast-​enhanced MRI, it was found that a strain 1 year with good functional status, and LVEF ≤35% despite ≥3 months of optimal pharmacological treatment [44]. In these last patients, recommendations derive largely from four large randomized trials [45–​48] from which LVEF ≤30–​35% became a principal variable for deciding who should receive an ICD. However, >50% of HF patients who die suddenly have a LVEF >30% [49]. Other independent univariate predictors of SCD have been identified including low NYHA class, unsustained VT, and inducibility of VT in EPS. However, they have a low positive predictive value, and better individual risk assessment to select HF patients who would benefit from an ICD placement is still needed, most of all considering the potential complications (inappropriate shocks and ICD infection) and the elevated cost of such devices. In addition, although techniques such as analysis of heart rate variability (HRV) and measurement of baroreflex sensitivity have shown an association between cardiac autonomic

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Im aging cardiac innervat ion

innervation abnormalities and SCD [50], they are of difficult use in clinical practice. In a phase 2, open-​label, multicentre study among 50 patients with LV dysfunction and previous MI, Bax et al. [51] found that late 123I-​mIBG SPECT defect score was the only variable that showed a significant difference between patients with and without positive EPS. A defect score of ≥37 yielded a sensitivity of 77% and specificity of 75% for predicting EPS results. Tamaki et al. [52] prospectively compared the predictive value of 123I-​mIBG imaging for SCD with that of the signal-​averaged ECG, HRV, and QT dispersion in 106 patients with chronic stable HF (LVEF 5 mm) has been associated with worse prognosis [14]. Septal morphology has been correlated with positive genetic study for sarcomeric mutations: a ‘reverse IVS’ is strongly associated with a positive genetic study, apical HCM or neutral morphology have a moderate probability, while a ‘sigmoid IVS’ has low probability of a positive genetic test [3]‌. To evaluate other localizations of hypertrophy, LV cavity opacification with contrast agents is helpful, especially in patients with suboptimal images. There is limited data on the value of three-​dimensional (3D) echo in HCM. It may be helpful in the reproducible assessment of LV geometry/​mass, and provides insight in LV outflow tract (LVOT) morphology/​dynamics [10]. CMR is the gold standard for WT and morphology assessment (E Fig. 42.1) and may detect LVH missed by echo (often anterolateral/​apical) [15]. Although WT measured by echo is often similar to CMR, discordance may be present [15], impacting diagnosis and SCD management. For the evaluation of LV mass and WT, cine CMR is performed (balanced steady-​state free-​ precession pulse sequence). Although LV mass is often not increased, it provides a baseline value for follow-​up. In the presence of flow or metal artefacts, a spoiled gradient-​echo pulse sequence should be used. Diagnostic criteria and measurement planes are similar to echo. In the presence of suboptimal echo quality or when CMR is contraindicated, CCT should be considered. Due to radiation and iodinated contrast, CCT is not used routinely. Because of low spatial resolution and radiation the use of CNI is not indicated.

The mitral valve and the mitral valve apparatus The majority of HCM patients have primary abnormalities of the mitral leaflets, with excessive tissue/​elongation (absolute or relative to LV size) [16], that contribute to LVOT obstruction (LVOTO) and mitral regurgitation (MR). The chordae are often elongated, with laxity and hypermobility. Papillary muscle abnormalities include anterior/​medial or apical displacement, hypertrophy, bifidity, and direct insertion into the anterior mitral leaflet. Though not specific for HCM (may be seen in HT, hypovolemia, inotropic drugs, after mitral surgery) [11], systolic anterior

As ses sm en t of a nato m y (a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

Fig. 42.1  CMR features in HCM. HCM with MV SAM and elongated anterior leaflet shown on the systolic cine image (a), and increased T1 relaxation times

(black arrow) compared to healthy myocardium on the native T1 map (b), but without focal fibrosis and absence of LGE (c). HCM in diastole (d) and systole (e) without MV SAM and absence of obstruction, but with extensive fibrosis on LGE (f). Apical HCM with spade-​shaped LV cavity in diastole (g) and typical thin-​ walled apical aneurysm in systole (asterisk, h) with LGE (i). LGE = late gadolinium enhancement; SAM = systolic anterior motion; MV = mitral valve.

motion (SAM) of the mitral valve is an important determinant of LVOTO [17]. Due to its high temporal resolution, the presence and severity of mitral SAM is best depicted with M-​mode: incomplete SAM (does not touch the IVS), mild SAM (mitral-​septal contact in late systole, 30% of systole) [18]. Mitral SAM leads to a mismatch in leaflet coaptation that classically results in eccentric posterior and lateral ‘SAM-​related’ MR, though this jet direction may also be found in organic valve disease [19].

The quantification of MR severity is performed according to the recommendations [20] and its dynamic component with exercise echocardiography [21]. In case of suboptimal image quality, transoesophageal echo may be considered. CMR is less accurate in the assessment of mitral valve leaflet and chordae morphology. However, it is the technique of choice to assess the papillary muscles, defining their contribution to LVOTO, essential in the selection of the type of invasive therapy [16]. The CMR quantification of MR severity is more reproducible and accurate than echo [22].

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CHAPTER 42  

Hy pe rt roph ic cardiomyopathy

CCT provides excellent definition of the mitral valve (MV) morphology [23] but it is seldom used with this sole purpose in HCM. CNI has no role in this setting.

LVOTO at rest is present in one-​third of HCM patients and is an independent determinant of adverse prognosis [17]. In another one-​third of patients, LVOTO is only seen after provocative manoeuvres [24]. The assessment of obstruction should be performed Intraventricular obstruction in resting condition and after provocative manoeuvres (e.g. Obstruction in HCM can occur at the LVOT or at the mid-​ Valsalva, standing, exercise). The use of nitrates or dobutamine is ventricular level, and its presence and location are suspected by not indicated, since it causes non-​physiological conditions and is not related to the disease itself [25]. Treadmill exercise echocardithe presence of turbulent colour Doppler flow (E Fig. 42.2). In LVOTO, mid-​systolic closure of the aortic valve and mitral ography (E Fig. 42.3, top) is the recommended technique to deSAM are best defined with M-​mode. The maximal flow velocity tect labile obstruction, mimicking real-​life conditions. Recordings is acquired using colour-​wave (CW) Doppler in apical views, and should be performed during exercise and at the beginning of retypically shows a late systolic peak, giving the spectral curve a covery, when preload decreases and obstruction may increase. ‘dagger shape’. HCM is defined as obstructive when peak flow vel- Exercise echocardiography should be considered in symptomatic ocity is >2.7 m/​s (peak gradient ≥30 mmHg) [7]‌. A gradient ≥50 patients if bedside manoeuvres fail to induce a LVOT peak gradient of ≥50 mmHg. Care should be taken to avoid contamination mmHg is considered haemodynamically relevant.

Fig. 42.2  Doppler assessment of left ventricular

outflow tract obstruction. 2D-​echo apical long-​ axis view with PW Doppler recording (top) demonstrating the mid-​systolic drop in ejection velocity (from dashed to solid line), until the peak outflow tract velocity, as seen on CW Doppler (solid line, bottom), creating a lobster claw shape of the PWD profile; the inflection point of the CW recording (bottom) shows a dagger-​shaped waveform (arrow) reflecting the mitral-​septal contact, and coincides with the drop in velocity seen on the PW recording, in the presence of a gradient >60 mmHg. LVOT = left ventricular outflow tract; LV = left ventricular; PW Doppler = pulsed-​wave Doppler; CW Doppler = continuous-​wave Doppler.

As ses sm en t of a nato m y

(a)

(c)

(b)

(d)

(e)

Fig. 42.3  Dynamic intraventricular obstruction and mitral valve motion. Transthoracic Doppler flow assessment in HCM during rest (a) and during exercise (b), where pressure gradient rises from 29 mmHg to 177 mmHg. Transoesophageal assessment before (c and d) and after myectomy and MV replacement (e) where obstruction is relieved and MV regurgitation is absent. TTE = transthoracic echocardiography; TEE = transoesophageal echocardiography; MV = mitral valve.

with the MR jet, overestimating obstruction severity. The MR signal starts earlier (after the end of the transmitral A wave) and ends later (at the onset of the transmitral E wave). Contributing factors for LVOTO include narrowing of the LVOT due to IVS hypertrophy and elongated mitral leaflets with SAM and leaflet-​septal contact in mid-​systole. Due to variable mitral valve anatomy, location of hypertrophy, loading conditions, and myocardial contractility, the degree of obstruction is unpredictable [26] and can even be paradoxical in response to exercise [21]. Mid-​ventricular obstruction, less common, is caused by mid-​ ventricular hypertrophy and/​or anomalous papillary muscle insertion that results in an ‘hourglass shaped’ LV chamber with a mid-​cavity gradient, frequently associated with apical aneurysms. Colour Doppler often shows aliasing in the sequestered apical area and a paradoxical apex to base diastolic gradient. LV apical aneurysms increase the risk for arrhythmias and thromboembolism. Apical HCM, with the typical ‘ace of spades’ sign, is less often associated with obstruction. CMR is useful in difficult cases of LVOTO, mid-​ventricular or apical hypertrophy, and in RV outflow tract obstruction [27]. The quantification of obstruction may be performed by CMR (in-​plane

acquisition to identify the highest velocity where aliasing occurs and a through-​plane acquisition to assess peak flow velocity), but it is still challenging [28]. CCT provides excellent visualization of the LVOT, the mitral apparatus, and localization of hypertrophy, especially due to the multiplanar reconstructions post acquisition but haemodynamic information cannot be obtained [29]. It is used for this purpose only when echo is suboptimal and CMR is contraindicated.

Tissue characterization CMR detects focal (late gadolinium enhancement, LGE) and diffuse (parametric mapping) myocardial fibrosis (E Fig. 42.1b, c, f, i). The LGE technique depends on local differences in contrast concentration. In areas of fibrosis, myocyte loss/​disruption or infiltration, gadolinium diffuses into the interstitial space and presents late wash-​out [30]. At image acquisition (10–​15 minutes after injection), areas of higher contrast concentration show an enhanced bright signal (shortened T1-​relaxation times). Approximately half of HCM patients show LGE, typically intramural, with heterogeneous extent and distribution. In hypertrophic segments it represents replacement fibrosis, while in non-​ hypertrophic areas, such as the RV insertion points, it corresponds

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to interstitial fibrosis and/​or myocyte disarray [31]. Thick filament sarcomeric HCM often show typical intramural LGE in hypertrophic areas, while a more diffuse distribution in atypical segments has been described in thin filament mutations [27, 32]. The extent of LGE in HCM (>10% of LV mass) is associated with outcomes (disease progression [33], LV dysfunction, hospitalization for HF, SCD, cardiovascular and all-​cause mortality) [7, 34, 35]. However, its independent value is debated, partially due to the lack of a standardized quantification method (a cut-​off value of 4 SD and 5 SD above the mean signal of remote myocardium yields the closest approximation to histopathology) [36]. Since LGE depends on focal differences between segments, diffuse fibrosis may not be recognized. A per pixel analysis of T1 relaxation times—​T1 mapping—​is promising. By comparing pre-​ and post-​contrast images it allows the estimation of the extracellular volume, reflecting interstitial fibrosis [37]. Post-​contrast T1 relaxation times in HCM are associated with non-​ sustained ventricular tachycardia [38] and may improve phenocopies identification (new automated algorithms such as radiomic analysis) [39]. Its overall diagnostic and independent prognostic value needs validation.

CCT also allows the visualization of fibrosis using a similar technique to LGE-​CMR. The iodinated agent accumulates in areas without regular myocyte structure, leading to higher density levels in fibrotic areas [40], depicted in images acquired at 7 minutes in retrospective ECG-​synchronized helical mode. Iodinated contrast, radiation, and inferior tissue characterization capabilities limit its clinical usefulness. Echocardiography and CNI only provide indirect information on tissue characterization [41].

Assessment of myocardial function LV systolic function Echocardiography is the first-​line technique. HCM patients often have normal LV ejection fraction (EF) but reduced indexed stroke volume due to small LV volumes (E Fig. 42.4). Despite the preserved left ventricular ejection fraction (LVEF), tissue Doppler imaging (TDI) and 2D-​speckle-​tracking echocardiography (2D-​STE) show that systolic function is often abnormal in HCM.

Fig. 42.4  Systolic function in HCM. Top: Normal LVEF and low indexed stroke volume; Bottom: Low systolic myocardial velocities (TDI) and abnormal GLS (2D-​STE).

GLS = global longitudinal strain; LVEF = left ventricular ejection fraction; STE = speckle-​tracking echocardiography; TDI = tissue Doppler imaging.

As ses sm en t of m yo ca rdia l f un c t i on TDI annular and regional LV systolic velocities (s’) are low and an s′ 14, LAVI ≥34 ml/​m2, CW peak velocity of tricuspid regurgitation >2.8 m/​sec and Ar-​A ≥30 ms. In the presence of severe MR, only the last two are valid. When the total available variables are three or four, LA pressure is elevated (grade II DD) if more than half meet the cut-​offs. When less than 50% of the variables meet the cut-​off values, LA pressure is normal (grade I DD). In case of 50% discordance with two or four available parameters, LVFP estimation is inconclusive. Finally, the estimation of LVFP is not recommended if only one parameter is available. In the presence of a restrictive pattern and reduced e’ (septal 12% of patients with intramural haematoma (IMH), the first imaging test was negative, and the condition was diagnosed in the second study after some hours or days [31]. On occasions, localized zones of the haematoma, which break the intima, can be identified giving rise to saccular images that may be confused with penetrating ulcers [32]. Evolution of the haematoma is highly dynamic, with complete reabsorption in more than half the cases or dissection in 40% being observed in the first six months. For this reason, closer follow-​up than that undertaken in patients with classical aortic dissection is advisable.

Penetrating atherosclerotic ulcer Penetrating atherosclerotic ulcer (PAU) is defined as an ulceration of an aortic atherosclerotic plaque penetrating the internal elastic lamina into the media, often associated with a variable degree of intramural haematoma formation (E Fig. 50.10b). Aortic ulcers are often multiple and may vary greatly in size (ranging (a)

from 5 mm in diameter and 4–​30 mm in depth). They can occur at any point throughout the aorta, most commonly in the middle and lower descending aorta, less frequently in the aortic arch and abdominal aorta, and rarely in the ascending aorta. Although the true prevalence of PAU is unknown, it may account for 2–​7% of all AAS [19]. Typically, patients with PAU are older (>70 years) than those with aortic dissection and present more often with extensive and diffuse atherosclerotic disease involving both the aorta and coronary arteries. An asymptomatic lesion may also be identified as an incidental finding and future research may be helpful to determine which findings should prompt further testing and/​or management changes. Among imaging modalities, contrast-​enhanced CT, including axial and multiplanar reformations, is considered the diagnostic technique of choice [33]. TEE may provide better morphological information than CT or MRI for the differential diagnosis of ulcerated plaques, PAUs, or ulcer-​like projections secondary to localized dissection in the evolution of IMH. The prognosis of ulcerated plaques and ulcer-​like projections is more benign than of symptomatic PAUs.

Echocardiography in the diagnostic strategy In clinical practice, TTE should be used as the first imaging modality to evaluate patients with suspected acute cardiovascular disease and is also useful in the differential diagnosis between AAS and acute coronary syndromes. TTE is a non-​invasive test, easily performed at the patient’s bedside, and rapid. However, it does not make it possible to definitively rule out AAS. A definitive diagnosis of type A dissection using TTE or contrast-​enhanced TTE in patients with shock should immediately be followed by surgery, provided that the diagnosis is confirmed using TEE in the operating theatre under general anaesthesia. Additionally, when the diagnosis seems to be definitive using CT. TTE should always be performed to assess the presence and aetiology of the aortic insufficiency, and to measure pericardial effusion and ventricular function. In hospitals with cardiac surgery and sufficient experience, TEE can be performed if the diagnosis by CT is not

(b)

Fig. 50.10  Evaluation of descending aorta by transoesophageal echocardiography in AAS. (a) aortic haematoma with typical crescentic thickening (arrows). (b) Penetrating aortic ulcer with an intramural haematoma in the internal part of the ulcer (*).

Ao = descending aorta; PAU = penetrating aortic ulcer.

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The role of ech o cardio gra phy

definitive or if haemodynamic instability renders it inadvisable to transfer a patient to other departments (E Fig. 50.11). TEE is semi-​invasive, can cause a rise in systemic pressure from gagging, and requires sedation. Strict control of blood pressure and adequate sedation are mandatory. Ideally, in type A or complicated type B aortic syndromes, TEE should be performed immediately before surgery or endovascular treatment, in the operating theatre under general anaesthesia, to avoid a rise in blood pressure that might cause an aortic rupture. After hyperacute phase, before cardiac care unit discharge, TEE is recommended to evaluate the residual anatomical and haemokinetic flows patterns of the false lumen that should be considered in the follow-​up and management of patients with residual patent false lumen.

Intraoperative and postoperative echo Echocardiography plays a crucial role in the preoperative, intraoperative, and postoperative assessment of aortic diseases. Knowledge of aortic root dimensions, aortic regurgitation severity, and its mechanisms would enable preoperative selection of the best surgical strategy and preparation of an adequately sized graft tube, repair, or replacement of aortic valve, and shorten surgical ischaemic time. Preoperative or intraoperative TEE is essential for planning surgical treatment of AAS and in deciding whether to replace the aortic valve, and may help to avoid early reoperations by showing correct connection of the distal part of the graft tube to the true lumen, supra-​aortic vessel involvement, and residual aortic regurgitation severity. Finally, intraoperative TEE may detect complications such as pseudoaneurysm formation, most of which are secondary to a leak in coronary artery reimplantation to the graft tube, communication of the distal part of the tube to the false lumen, significant aortic regurgitation, periaortic haemorrhage, or segmental abnormalities in left ventricular contraction. Intraoperative TEE is also highly useful during endovascular therapy, especially in type B aortic dissection (E Fig. 50.11, z Video 50.5). It permits correct guidewire entrance by identifying the true lumen in aortic dissections, provides additional information helpful for guiding correct stent-​graft positioning and identifies suboptimal results and the presence of leaks and/​or small re-​entry tears (E Fig. 50.12, z Video 50.6), with much higher sensitivity than angiography [34, 35]).

Suspected aortic dissection

CT

TTE*

Type A

Type B

Type A

Type B

TTE

TEE‡

Surgery TEE§

TEE‡ or CT

Surgery TEE§

Fig. 50.11  Diagnostic algorithm in patients with suspected acute aortic

dissection. * If TTE is the initial test and is negative, further testing might be warranted. ‡ Depending on availability, complications, and examiner experience. § Definitive diagnosis of type A dissection by TTE permits an unstable haemodynamic patient to be sent directly to surgery. Intraoperative TEE will be performed before surgery. TEE = transoesophageal echocardiography; TTE = transthoracic echocardiography.

applications of transoesophageal echocardiography are to define entry tear location and size, the mechanisms and severity of aortic regurgitation, and flow dynamics of the two lumina. Contrast enhancement substantially improves haemokinetic information on aortic dissection which may improve prognostic assessment and adequate patient management. Three-​ dimensional TEE is highly useful in entry tear size evaluation. The diagnostic imaging strategy should be individualized according to patient’s condition, the relevant diagnostic questions to be answered and local institutional factors, such as expertise and technological availability. TEE should be used in the intraoperative monitoring of surgical and endovascular treatment of aortic diseases.

Conclusions Echocardiography is a reference imaging technique for the diagnosis and follow-​up of aortic diseases. Its main advantages are that it is portable, rapid, and does not require irradiation. TTE appears to suffice for aortic root and proximal ascending aorta assessment and may be useful to establish a rapid diagnosis of aortic dissection, mainly with the use of contrast. The main

Fig. 50.12  Control after thoracic aorta endovascular treatment by contrast

TEE showing a distal type I endoleak (large arrows), owing to lack of correct apposition of the distal part of the stent (small arrows) with the presence of a thrombus (*).

RE F E RE N C E S

References 1. Goldstein SA, Evangelista A, Abbara S, et al. Multimodality imaging of diseases of the thoracic aorta in adults: from the American Society of Echocardiography and the European Association of Cardiovascular Imaging: endorsed by the Society of Cardiovascular Computed Tomography and Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr 2015; 28: 119–​82. 2. Moral S, Avegliano G, Cuéllar H, et al. Usefulness of Transesophageal Echocardiography in the Evaluation of Celiac Trunk and Superior Mesenteric Artery Involvement in Acute Aortic Dissection. J Am Soc Echocardiogr 2020 Dec 30;S0894–7317(20)30813–0. 3. Campens L, Demulier L, De Groote K, et al. Reference values for echocardiographic assessment of the diameter of the aortic root and ascending aorta spanning all age categories. Am J Cardiol 2014; 114: 914–​20. 4. Evangelista A, Gallego P, Calvo-​Iglesias F, et al. Anatomical and clinical predictors of valve dysfunction and aortic dilation in bicuspid aortic valve disease. Heart 2018; 104: 566–​73. 5. Vis JC, Rodríguez-​Palomares JF, Teixidó-​Turá G, et al. Implications of asymmetry and valvular morphotype on echocardiographic measurements of the aortic root in bicuspid aortic valve. J Am Soc Echocardiogr 2019; 32: 105–​12. 6. Rodríguez-​ Palomares JF, Teixidó-​ Turá G, Galuppo V, et al. Multimodality assessment of ascending aortic diameters: comparison of different measurement methods. J Am Soc Echocardiogr 2016; 29: 819–​26.e4. Erratum in: J Am Soc Echocardiogr 2016; 29: 1206. 7. Evangelista A. Imaging aortic aneurysmal disease. Heart 2014; 100: 909–​15. 8. Erbel R, Aboyans V, Boileau C, et al. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J 2014; 35: 2873–​926. Erratum in: Eur Heart J 2015; 36: 2779. 9. Aboyans V, Bataille V, Bliscaux P, et al. Effectiveness of screening for abdominal aortic aneurysm during echocardiography. Am J Cardiol 2014; 114: 1100–​4. 10. le Polain de Waroux JB, Pouleur AC, et al. Functional anatomy of aortic regurgitation: accuracy, prediction of surgical repairability, and outcome implications of transesophageal echocardiography. Circulation 2007; 116(11 Suppl): I264–​9. 11. Shiga T, Wajima Z, Apfel CC, Inoue T, Ohe Y. Diagnostic accuracy of transesophageal echocardiography, helical computed tomography, and magnetic resonance imaging for suspected thoracic aortic dissection: systematic review and meta-​analysis. Arch Intern Med 2006; 166: 1350–​6. 12. Evangelista A, Isselbacher EM, Bossone E, et al. Insights from the international registry of acute aortic dissection: a 20-​year experience of collaborative clinical research. Circulation 2018; 137: 1846–​60. 13. Meredith EL, Masani ND. Echocardiography in the emergency assessment of acute aortic syndromes. Eur J Echocardiogr 2009; 10: i31–​9. 14. Victor MF, Mintz GS, Kotler MN, Wilson AR, Segal BL. Two dimensional echocardiographic diagnosis of aortic dissection. Am J Cardiol 1981; 48: 1155–​9. 15. Khandheria BK, Tajik AJ, Taylor CL, et al. Aortic dissection: review of value and limitations of two-​dimensional echocardiography in a six-​year experience. J Am Soc Echocardiogr 1989; 2: 17–​24. 16. Iliceto S, Antonelli G, Biasco G, Rizzon P. Two-​dimensional echocardiographic evaluation of aneurysms of the descending thoracic aorta. Circulation 1982; 66: 1045–​9.

17. Evangelista A, Avegliano G, Aguilar R, et al. Impact of contrast-​ enhanced echocardiography on the diagnostic algorithm of acute aortic dissection. Eur Heart J 2010; 31: 472–​9. 18. Cecconi M, Chirillo F, Costantini C, et al. The role of transthoracic echocardiography in the diagnosis and management of acute type A aortic syndrome. Am Heart J 2012; 163: 112–​18. 19. Evangelista A, Carro A, Moral S, et al. Imaging modalities for the early diagnosis of acute aortic syndrome. Nat Rev Cardiol 2013; 10: 477–​86. 20. Erbel R, Börner N, Steller D, et al. Detection of aortic dissection by transoesophageal echocardiography. Br Heart J 1987; 58: 45–​51. 21. Ballal RS, Nanda NC, Gatewood R, et al. Usefulness of transesophageal echocardiography in assessment of aortic dissection. Circulation 1991; 84: 1903–​14. 22. Sommer T, Fehske W, Holzknecht N, et al. Aortic dissection: a comparative study of diagnosis with spiral CT, multiplanar transesophageal echocardiography, and MR imaging. Radiology 1996; 199: 347–​52. 23. Evangelista A, Garcia-​ del-​ Castillo H, Gonzalez-​ Alujas T, et al. Diagnosis of ascending aortic dissection by transesophageal echocardiography: utility of M-​mode in recognizing artifacts. J Am Coll Cardiol 1996; 27: 102–​7. 24. Keren A, Kim CB, Hu BS, et al. Accuracy of biplane and multiplane transesophageal echocardiography in diagnosis of typical acute aortic dissection and intramural hematoma. J Am Coll Cardiol 1996; 28: 627–​36. 25. Nienaber CA, von Kodolitsch Y, Nicolas V, et al. The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N Engl J Med 1993; 328: 1–​9. 26. Evangelista A, Salas A, Ribera A, et al. Long-​term outcome of aortic dissection with patent false lumen: predictive role of entry tear size and location. Circulation 2012; 125: 3133–​41. 27. Evangelista A, Aguilar R, Cuellar H, et al. Usefulness of real-​time three-​dimensional transoesophageal echocardiography in the assessment of chronic aortic dissection. Eur J Echocardiogr 2011; 12: 272–​7. 28. Agricola E, Slavich M, Rinaldi E, et al. Usefulness of contrast-​enhanced transoesophageal echocardiography to guide thoracic endovascular aortic repair procedure. Eur Heart J Cardiovasc Imaging 2016; 17: 67–​75. 29. Bossone E, Evangelista A, Isselbacher E, et al. Prognostic role of transesophageal echocardiography in acute type A aortic dissection. Am Heart J 2007; 153: 1013–​20. 30. Movsowitz HD, Levine RA, Hilgenberg AD, Isselbacher EM. Transesophageal echocardiographic description of the mechanisms of aortic regurgitation in acute type A aortic dissection: implications for aortic valve repair. J Am Coll Cardiol 2000; 36: 884–​90. 31. Evangelista A, Mukherjee D, Mehta RH, et al. Acute intramural hematoma of the aorta: a mystery in evolution. Circulation 2005; 111: 1063–​70. 32. Evangelista A, Dominguez R, Sebastia C, et al. Long-​term follow-​up of aortic intramural hematoma: predictors of outcome. Circulation 2003; 108: 583–​9. 33. Evangelista A, Czerny M, Nienaber C, et al. Interdisciplinary expert consensus on management of type B intramural haematoma and penetrating aortic ulcer. Eur J Cardiothorac Surg 2015; 47: 209–​17. 34. Koschyk DH, Nienaber CA, Knap M, et al. How to guide stent-​graft implantation in type B aortic dissection? Comparison of angiography, transesophageal echocardiography, and intravascular ultrasound. Circulation 2005; 112(9 Suppl): I260–​4. 35. Rocchi G, Lofiego C, Biagini E, et al. Transesophageal echocardiography-​guided algorithm for stent-​graft implantation in aortic dissection. J Vasc Surg 2004; 40: 880–​5.

9 For additional multimedia materials please visit the online version of the book at M oxfordmedicine.com/esccvimaging3

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Aortic disease: Aneurysm and dissection—​role of CMR Jose F. Rodriguez-​Palomares and Arturo Evangelista Contents

Introduction  757 Magnetic resonance imaging techniques  757

Cine-​MR sequences  757 Black-​blood sequences  758 Flow mapping  758 Non-​contrast-​enhanced MR angiography (NCE-​MRA)  759 Contrast-​enhanced MR angiography (CE-​MRA)  759

Normal aorta and common variants  759 Aortic measures  760 Diagnosis of thoracic aortic diseases  761

Atherosclerosis  761 Aortic aneurysms  762 Acute aortic syndromes  762 Acute aortic syndrome in blunt trauma  767 Aortitis  767 Aortic coarctation  768 Pitfalls and limitations  768

Introduction Diseases of the aorta include a group of cardiovascular disorders such as aortic aneurysm, acute aortic syndrome, traumatic aortic disease, arteriosclerotic, inflammatory, genetic (such as Marfan’s syndrome), and congenital diseases (such as coarctation of the aorta). In the last decade, there has been an increase in the overall death rate from aortic aneurysms and acute aortic syndromes worldwide with higher rates in males [1]‌. However, aortic diseases can have a long subclinical period, with acute aortic syndromes or aortic rupture being the first manifestation of the disease. These presentations require a rapid diagnosis to guide patient management and improve prognosis. The diagnosis of aortic diseases focuses on the use of different imaging techniques such as echocardiography, cardiovascular magnetic resonance (CMR), and computed tomography (CT). CMR has proven to be a reliable and reproducible imaging modality owing to its capacity for multiplanar imaging without the use of iodine-​containing contrast agents or ionizing radiation and, thus, is becoming one of the first-​line techniques for the evaluation of thoracic aortic diseases.

Magnetic resonance imaging techniques Cine-​MR sequences Cine-​MR images are acquired using steady-​state-​free-​precession (SSFP) sequences that provide excellent contrast between blood pool and surrounding tissue without the use of contrast agents. SSFP sequences (TrueFISP, Fiesta, or Balanced FFE) very short acquisition times since they have very low repetition times. Given the high temporal resolution of cine-​MR, images of multiple phases of the cardiac cycle can be obtained and blood flow visualized during both systole and diastole. Non-​contrast single-​shot SSFP imaging enables us to rapidly rule out aortic dissection and is particularly useful for patients incapable of breath-​holding or in the setting of suspected aortic syndrome [2, 3]. SSFP sequences generate images of brilliant blood (z Video 51.1). These images also show turbulent flow in haemodynamically significant stenosis or valvular regurgitation that may be useful to detect aortic coarctation or valvular disease. When evaluating the aorta, which contains areas of turbulent high-​velocity flow, spoiled gradient-​echo cine sequences can be helpful as they tend to be less prone to flow-​ related artefacts than SSFP.

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Black-​blood sequences Blood circulating through the aorta is black on conventional spin-​echo and turbo spin-​echo sequences. In order to optimize the quality of the aortic images, acquisition is performed with electrocardiographic (ECG)-​gating, during mid-​to-​late diastole and during repeated breath-​holds. A slice thickness of 3–​8 mm and echo time of 20–​30 ms are standard, while repetition time is determined by the R-​R´ interval of the ECG. ECG-​triggered, breath-​hold turbo spin echo (TSE) has been the cornerstone of black-​blood CMR for aortic disease. Rapid black-​blood spin-​echo sequences such as HASTE or SS-​FSE sequences (Half Fourier sampling, single-​shot) permit correct morphological assessment of the aorta with very rapid acquisition times. These sequences provide excellent morphological information on the aortic wall and adjacent structures [4]‌. T1-​or T2-​ weighted images are useful for wall tissue characterization. Spin-​echo T1-​weighted imaging provides the best anatomic details of intramural haematoma, intimal flaps (E Fig. 51.1) or atheroma. T2-​weighted images demonstrate oedema as a high signal and can provide useful information on the activity of inflammatory aortic conditions. Post-​contrast T1 imaging with fat suppression is useful for diagnosing some entities such as aortitis or mycotic aneurysms.

Flow mapping Accurate quantitative information on blood flow is obtained from modified gradient-​echo sequences with parameter reconstruction from the phase rather than the amplitude of the MR signal. This is also known as flow mapping or phase contrast (PC) or velocity-​ encoded (VENC) cine-​ CMR. VENC cine-​CMR sequences provide useful functional information owing to their capacity to quantify flow in different valvular and aortic diseases. The information is processed using magnitude and phase images. Signal magnitude images display brilliant flowing blood and offer better anatomical assessment, while phase images show a map of flow velocities and direction (z Video 51.2). Quantitative data on flow are estimated by multiplying the spatial mean velocity and cross-​sectional area

(a)

of the vessel. Using post-​processing techniques, it is possible to obtain curves of flow vs. time and peak velocity vs. time. In this manner, the haemodynamic parameters can be quantified in different situations such as aortic coarctation or valvular disease, and in the analysis of flow patterns in the true and false lumina of aortic dissection. The main limitation of this sequence is that it permits only encoding of the velocity in a single direction of the space. However, pulsatile blood flow through the cavities of the heart and great vessels is multidirectional and multidimensional. In recent years, three-​dimensional (3D) cine (time-​resolved) PC CMR with three-​directional velocity encoding has been developed to achieve more detailed study of intravascular and intracardiac flows. This sequence, also known as 4D-​flow CMR, refers to a PC with flow-​encoding in all three spatial directions and time throughout the cardiac cycle [5]‌(z Video 51.3). It permits flow volume quantification comparable to 2D cine PC CMR and has good scan and re-​scan repeatability. Compared to 2D-​PC CMR, the 4D flow sequence has several advantages. Using the principle of ‘conservation of mass’ (e.g. the estimation of the Qp/​Qs within the same data set) it allows us to investigate the internal consistency of data. A further advantage is the retrospective placement of different analysis planes at any location within the acquisition volume (mainly in cases where multiple 2D cine PC-​CMR scans would be needed). Recently, the consensus document of experts established that 4D-​flow sequences are clinically useful for studying valvular diseases (stenosis and regurgitation), shunts, and collateral flow, complex congenital heart diseases, and diseases of the aorta. Although data remain limited, these sequences can also be considered in the study of intracardiac flow [6]‌. Furthermore, 4D-​flow sequences permit the analysis of conventional parameters such as flow volume or regurgitant fraction or more advanced parameters such as wall shear stress or turbulent kinetic energy [7]‌. It is important to note that the majority of these in-​vivo haemodynamic measurements cannot be assessed non-​invasively with any other imaging technique. These complex parameters are significant for increasing our knowledge of the pathophysiology of the cardiovascular system; however, further

(b)

Fig. 51.1  Axial T1-​weighted turbo spin-​echo sequences in two patients with an aortic dissection: (a) shows the presence of a flap in the proximal descending

aorta (arrow) and (b) shows the presence of a flap in the abdominal aorta (*). The images display the presence of two lumina in the aorta the false lumen being the one with the bigger size (arrow and *).

N or m a l aorta a n d c o m mon va ria n ts longitudinal studies should evaluate the real influence of these parameters in aortic dilation and aortic diseases.

Non-​contrast-​enhanced MR angiography (NCE-​MRA) Three-​dimensional (3D) NCE-​MRA has proved useful in any vascular anatomy throughout the body, owing to the potential risk of contrast-​induced nephrogenic systemic sclerosis in patients with severe renal failure. Different physical mechanisms have been developed for NCE-​MRA sequences (inflow effect, flow-​dependency on cardiac phase, flow-​encoding, spin labelling and relaxation), which provide high-​quality 3D data including motion-​free images of the aorta when combined with ECG-​gating and respiratory navigation [8, 9] (E Fig. 51.2). The whole data set of the thoracic aorta can be acquired in only a few minutes with high signal-​to-​noise (SNR) and contrast-​to-​noise ratios (CNR), with the pitfall of potential flow artefacts secondary to flow disturbance and high-​velocity jets. The non-​contrast-​enhanced SSFP MRA sequences have similar accuracy as contrast-​ enhanced MRA [10].

acquisition techniques, multiphasic time-​resolved 3D MRA images are obtained with high temporal and spatial resolution. In these sequences, contrast injection is started at the same time as image acquisition, using the first set of images as a mask for posterior subtraction using post-​processing techniques through MIP and MPR reconstructions (z Video 51.4). They are very useful in the study of aortic dissection and shunts. If metallic devices related to the aorta are present (such as stents or adjacent embolization coils), the quality of CMR images may be limited by off-​resonance artefacts that preclude optimal evaluation (z Video 51.1).

Normal aorta and common variants

The aorta is the main artery in the body and its size does not exceed 40 mm in healthy adults. In an older paediatric patient, comparison with Z-​score (the number of standard deviations above or below the predicted mean normal diameter) can be helpful [11]. This diameter is influenced by age, sex, body size, and blood pressure and the normal rate of expansion is approximately 0.9 mm /​10 years in men and 0.7 mm/​10 years in women Contrast-​enhanced MR angiography [12]. Thus, normal aortic dimensions should be indexed by body (CE-​MRA) size and age, and an aortic diameter > 21 mm/​m2 is considered CE-​MRA images are obtained by T1-​weighted 3D-​gradient-​ abnormal. Progressive aortic dilation in adults is due to ageing, echo sequences, following intravenous contrast administration higher collagen-​to-​elastin ratio, atherosclerosis, and an increase through the shortening effect on T1 of gadolinium contrast. in stiffness and pulse pressure. Exercise training per se has only a These sequences offer important anatomical information on limited impact on aortic remodelling, and the upper limit values both the aorta and main collateral vessels (E Fig. 51.3). This of the aorta (99th percentile) are 40 mm in men and 34 mm in technique is suitable for the depiction of abnormalities such women [13]. The most common congenital vascular anomaly of the aortic as penetrating atherosclerotic ulcer, dissection, coarctation, and aneurysm. The acquired images must be re-​evaluated by arch, occurring in approximately 1% of individuals, is the aberrant post-​ processing maximum intensity projection (MIP) and right subclavian artery arising distal to the left subclavian artery, multiplanar reconstruction (MPR) reconstructions. By the coursing to the right and passing behind the oesophagus. A common application of ultrarapid spoiled gradient-​echo sequences in brachiocephalic trunk, in which both common carotid arteries and steady-​state free precession and the implantation of parallel the right subclavian artery arise from a single trunk off the arch,

(a)

(b)

(c)

Fig. 51.2  Non-​contrast-​enhanced MR angiography (NCE-​MRA) with 2D reconstructions in an axial (a), coronal (b), or sagittal (c) plane. The dark left

ventricular cavity (b) is secondary to the presence of a severe aortic regurgitation that induces flow artefacts due to flow disturbance and high-​velocity jet.

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(b)

Fig. 51.3  Contrast-​enhanced MR

angiography of the aorta in a sagittal view: maximum intensity projection (MIP) (a) and 3D reconstruction (b). Note the common take-​off of the right brachiocephalic trunk and the left carotid artery (bovine aortic arch) (arrows).

is the most frequent normal variant of the aortic arch branching. This so-​called bovine trunk occurs in 10–​22% of individuals; it does not produce symptoms although it has been postulated that it could be related to other aortic diseases [14] (E Fig. 51.3). A right-​sided aortic arch (aortic arch passing to the right of the trachea) is associated with two principal branching patterns: mirror image branching, which is associated with a high rate of congenital cardiac anomalies, and right aortic arch with aberrant left subclavian artery which has little association with other abnormalities.

Aortic measures The anatomic locations at which the ascending aorta diameter has to be measured are: aortic annulus, sinuses of Valsalva, the sinotubular junction, and the ascending aorta at the pulmonary trunk. Other measurement sites include the aortic arch between the brachiocephalic and left subclavian artery, isthmus (just below the left subclavian artery) and proximal descending aorta at pulmonary trunk level. Measurements of the abdominal aorta include those at diaphragmatic level, coeliac trunk, renal arteries and prior to the iliac artery bifurcation [13].

Measurements of the aorta can be taken using both CE-​MRA or NCE-​MRA (E Figs. 51.2 and 51.3). Post-​processing techniques (MIP, MPR, and rendering volume) facilitate visualization of the entire aorta and its principal branches and are highly useful when planning treatment. Furthermore, cine images can be used for measuring the luminogram of the aorta at an end-​diastolic frame. However, owing to movement of the valvular plane, aortic root measurement needs to be taken with cine SSFP sequences since the resolution and image quality are better compared to angiography (E Fig. 51.4). Aortic diameters should be assessed in end-​diastole and using the internal diameter of the aorta. Excellent accuracy has been observed using this method in CMR compared to CT and two-​ dimensional transthoracic echocardiography [15]. Absolute measurements are not good predictors of abnormality severity, and should be considered relative to age, sex, and body surface area [16]. When patients with aortic disease are followed over time it is necessary to measure the aortic diameters in the same location and same spatial plane to ensure correct monitoring. Although the sagittal plane permits a more reproducible evaluation [17], aortic diameters have to be measured in an imaging plane perpendicular to the aorta at the desired level (double oblique technique) (E Fig. 51.4c).

Diag n o si s of thor aci c aort i c di se ase s (a)

(b)

(c)

Fig. 51.4  Aortic root measurements at the level of the sinuses of Valsalva using the cusp-​to-​cusp convention (a) and the cusp-​to-​commissure convention (b) based on SSFP cine images. Measurements of the ascending aorta and proximal descending aorta at the level of the pulmonary bifurcation (c) from contrast-​ enhancement angiography.

The sinuses of Valsalva are commonly measured by CMR between the inner edges from commissure to opposite sinus [15, 18]. However, diameters measured using the cusp-​to-​cusp convention are generally a mean of 2.5 mm larger compared to those measured by the cusp-​to-​commissure method, present closer agreement with echocardiographic measurements, and greater feasibility in bicuspid aortic valves [19, 20]. Perimeter measurements of the annulus, as used for valvular sizing prior to transcatheter aortic valve replacement, showed good agreement with CT measurements [21]. In the rest of the aorta, the anteroposterior diameter and one perpendicular to this one (latero-​lateral) should be performed (E Fig. 51.4). The presence of aortic root asymmetry should be mentioned. An asymmetric root is more common in patients with bicuspid aortic valve (BAV) owing to dilation opposite the commissural fusion and can also be seen in patients with Marfan syndrome. An aortic root can be defined as asymmetric when the largest cusp-​to-​cusp diameter differs ≥5 mm from the smallest. Of note, underestimation of aortic root diameter by transthoracic echocardiography compared to CMR can be greater in the presence of an asymmetric root or in BAV patients with fusion of the right-​ to-​non-​coronary sinus. These patients may benefit from a CMR study to ensure the real largest diameter [20].

(a)

CMR has been established as an accurate non-​invasive tool for the assessment of aortic distensibility and pulse-​wave velocity. These methods have been used to assess aortic elasticity in patients with Marfan syndrome, BAV, or aortic aneurysms [22, 23]. They could be of clinical value for the identification of patients at high risk of aortic complications.

Diagnosis of thoracic aortic diseases Atherosclerosis CMR is a non-​invasive imaging modality that can visualize and characterize the composition of atherosclerotic plaques and differentiate tissue structure based on proton magnetic properties with excellent soft tissue contrast. CMR sequences are highly useful for the detection of aortic atheroma and offer information on late repercussions of the plaque in the aortic lumen at an advanced stage of the disease. Structural alterations occurring in the aortic wall must be observed for accurate assessment of atheromatous plaques. Black-​blood TSE sequences are very useful and promising for identifying and characterizing aortic plaques and distinguishing its components in vivo.

(b)

Fig. 51.5  Axial images showing severe atherosclerosis in the proximal descending aorta. The CMR suggests the presence of a fibrocellular plaque being

isointense in T1-​weighted images (a, white arrows and *) and hyperintense in T2-​weighted images (b, yellow arrows and *). Note the presence of a black circumferential artefact in the descending aorta (b) secondary to the presence of a chemical shift artefact between the atherosclerotic plaque and the not perfectly nulled blood pool.

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Being composed of cholesterol esters, the lipid nucleus has a short T2-​and will appear hypointense on T2-​weighted images; however, in T1-​weighted images, it appears hyperintense. Fibrocellular components of the plaque are hyperintense in T2-​ and isointense in T1-​weighted images (E Fig. 51.5). Calcium deposits can be seen as hypointense regions within the plaque on T1-​, proton density-​and T2-​weighted images. The fibrous cap, lipid core, organized or fresh thrombus, calcification, or necrotic areas have been well-​characterized in studies performed both in vitro and in vivo. Fayad et al. [24] showed that CMR evaluation of the aorta compared well with transoesophageal echocardiography (TEE) for the assessment of aortic atherosclerotic plaque thickness, extent, and composition. Furthermore, high-​ resolution, non-​invasive CMR demonstrated regression of aortic atherosclerotic lesions secondary to lipid lowering by simvastatin [25]; thus, it can be used to monitor progression and regression of atheromatous plaques. A very promising aspect is the capability of CMR to detect inflammatory activity of atheromatous plaque with the administration of contrast media. Inflammatory phenomena that determine macrophage accumulation can be demonstrated as hyperuptake of gadolinium chelates or ultrasmall superparamagnetic particles of iron oxides (USPIO) in plaque [26]. However, in recent years, other methods have been proposed to study the inflammatory activity of atherosclerotic plaques. On the one hand, T2-​mapping sequences permit accurate quantification of the lipid content in the plaque in a non-​invasive manner. It has been shown that, compared to asymptomatic plaques, the lipid concentration is greater in symptomatic plaques despite both having the same degree of luminal stenosis [27]. On the other hand, positron emission tomography-​magnetic resonance imaging (PET-​CMR) has been proposed as a promising imaging technique to assess atherosclerotic plaque activity. Fluorine-​18 (18F)-​ labelled fluorodeoxyglucose (18F-​FDG) and 18F-​sodium fluoride (18F-​NaF) PET have been associated with inflammation and microcalcifications, respectively [28]. A recent study using PET-​CT demonstrated that fluorine-​18-​NaF may identify disease activity in patients with abdominal aorta aneurysms and could be an added predictor of aneurysm growth and future clinical events [29]. Further studies will demonstrate the real role of PET-​CMR in the follow-​up of patients with aortic atherosclerosis for evaluating the response to treatment and predicting adverse events. TEE and CMR are powerful non-​invasive tools for visualizing aortic atheroma. TEE is the technique of choice in patients with stroke or peripheral embolism since it affords excellent assessment of complicated plaque size and mobility. Unlike TEE, CMR can visualize the entire thoracic aorta including the small section of ascending aorta which is obscured by the tracheal air column. Cine-​CMR may also permit the assessment of complex plaque and aortic debris mobility with thrombus formation.

Aortic aneurysms Thoracic aortic aneurysmal disease usually occurs as a result of atherosclerotic, inflammatory (such as aortitis), inherited (such as Marfan’s syndrome) or haemodynamic conditions (such as

aortic valve disease, trauma, or coarctation). Aneurysms are often incidentally discovered on imaging, with the ascending aorta most commonly involved [30]. An aneurysm is diagnosed when the ascending aorta is >5 cm, the descending aorta >4 cm and the Z-​score ≥2 in the paediatric population [13]. CMR is a robust tool for evaluating aortic aneurysms. Three-​ dimensional CE-​MRA is highly accurate at depicting the location, extent and precise diameter of an aneurysm and its relationship with aortic branch vessels (EFigs. 51.3 and 51.4). It is recommended to combine MRA images with spin-​echo black-​blood images (E Fig. 51.1), which are very useful for detecting alterations in the wall and adjacent structures. In mycotic aneurysm, T2-​weighted and post-​contrast T1-​weighted images permit identification of inflammatory changes in the aortic wall and adjacent fat, secondary to bacterial infection. Periaortic haematoma and areas of high signal intensity within the thrombus may indicate aneurysm instability and are well depicted on spin-​echo images. The capability of CE-​MRA to visualize the Adamkiewicz artery represents an advance in planning surgical thoracic aneurysm repair, thereby preventing postoperative neurological deficits secondary to spinal cord ischaemia [10]. As these sequences are rapid and simple to perform, they play a major role in efficient aneurysm follow-​up (E Fig. 51.6). When the aneurysm affects the ascending aorta, it is recommended to conduct a functional study through the aortic valve using cine-​CMR and velocity-​encoded sequences to rule out associated valvular disease. The aortic cusps should be described as bicuspid (BAV) or tricuspid, which has a significant impact on tailoring the therapeutic strategy. In recent years, 4D-​flow sequences have added understanding of aortic dilation pathophysiology in BAV patients. BAV induces greater rotational flow which produces abnormal and asymmetric wall shear stress in the ascending aorta that determines its dilation (z Video 51.3) [7, 31]. The principal predictor of aortic rupture or dissection is aortic size. In a large retrospective study of patients with thoracic aortic aneurysms of different aetiologies (excluding genetic disorders), the 5-​year risk of rupture or dissection was 1.1% in patients with an aortic diameter of 50 mm, and 2.9% when the aortic diameter was ≥55 mm [32]. Furthermore, the probability of complications at follow-​up is similar in patients with BAV compared to TAV if the aortic diameter is similar [33, 34]. The mean growth rate for all thoracic aneurysms is about 1 mm/​ year. The growth rate is significantly higher for aneurysms of the descending aorta, 1.9 mm/​year, than those of the ascending aorta, 0.7 mm/​year. In addition, dissected thoracic aneurysms grow significantly more rapidly (1.4 mm/​year) than non-​dissected aneurysms (0.9 mm/​year) [30]. In a more recent study, Davies et al. [16] recommended elective operative repair before the patient enters the zone of moderate risk of an aortic size index higher than 2.75 cm/​m2.

Acute aortic syndromes Acute aortic syndromes include aortic dissection, intramural haematoma (IMH), penetrating atherosclerotic ulcers (PAU), and

Diag n o si s of thor aci c aort i c di se ase s (a)

(b)

(c)

Fig. 51.6  Contrast-​enhanced MR angiography of the aorta in a sagittal view (3D reconstruction) in a patient with an aneurysm of the ascending aorta and

proximal arch (a), a patient with a bicuspid aortic valve with a dilatation of the aortic root and ascending aorta (b) and a patient with a degenerative aneurysm in the aortic arch (c).

traumatic partial or total rupture. As they are associated with high morbidity and mortality rates, their early recognition is vital to ensure prompt treatment [35].

Aortic dissection Aortic dissection is characterized by a laceration of the aortic intima and inner layer of the aortic media that allows blood to course through a false lumen in the outer third of the media. Diagnosis of aortic dissection is based on demonstration of the intimal flap separating the true from false lumina (E Fig. 51.1, z Videos 51.2 and 51.4). In the acute phase, the use of CMR is often limited by poor availability, patient claustrophobia, and time-​consuming study. A meta-​analysis [36] showed diagnostic accuracy to be practically the same (95–​100%) for CT, TEE, and CMR. Most shortcomings are due to user interpretation errors rather than the technique itself. However, analysis of the International Registry of Aortic Dissection (IRAD) [35] showed CT to be the most frequently used imaging technique (61%) in acute patients followed by echocardiography (33%). In suspected aortic dissection, the standard CMR protocol should begin with black-​blood sequences (E Fig. 51.1). In type B dissection, it is important to acquire images with a wide field-​ of-​view that includes the whole aorta from the arch to the aortic bifurcation. In the axial plane, the intimal flap is detected as a straight linear structure within the aortic lumen. The true lumen can be differentiated from the false by anatomical features and flow pattern: the true lumen shows a signal void, whereas the false lumen has higher signal intensity (E Fig. 51.7). High signal intensity of pericardial effusion indicates blood components and is a sign of impending ascending aorta rupture into the pericardial

space. Similarly, the presence of pleural effusion is an indicator of impending aortic rupture. CE-​MRA has proved to be superior to black-​blood sequences in the assessment of dissection extension and supra-​aortic trunk involvement. However, owing to the limitation of this technique in visualizing the aortic wall and adjacent structures, the aortic dissection protocol should include both sequences [37]. Detailed anatomical information on aortic dissection must describe dissection extension and branch vessel perfusion from the true or false lumen. Gradient-​echo sequences and PC images can help identify aortic regurgitation, entry sites, and differentiate slow flow from thrombus in the false lumen (E Fig. 51.8, z Video 51.2). Also, PC sequences have a promising role in the functional assessment of aortic dissection through the quantification of flow in both lumina and the possibility of establishing haemodynamic patterns of progressive dilation risk. An increased false lumen pressure is an important factor associated with false lumen enlargement and, thus, aortic dilation. Indirect signs of high false lumen pressure include true lumen compression, partial thrombosis of the false lumen or the velocity pattern of the false lumen flow. For planning surgery or endovascular repair, it is useful to demonstrate the course of the flap, entry tear location, false lumen thrombosis, aortic diameter, and main arterial trunk involvement by post-​processed techniques with MPR reconstructions, MIP, and volume rendering (E Fig. 51.8). It is mandatory to visualize the native images from CE-​MRA (2D images) since the flap may not be seen on the volumetric reconstruction [38]. Time-​resolved MRA provides additional functional information compared to conventional MRA, such as the dynamic assessment of blood flow in entry tears and may help identify the entry and exit points of

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(a)

(b)

(c)

(d)

Fig. 51.7  Aortic dissection: (a) Single-​shot SSFP sequence in a coronal view showing a patient with a type A aortic dissection (black arrows showing the

intimal flap), (b) T1-​weighted turbo spin-​echo sequence in an axial view of the same patient (white * showing the intimal flap in the ascending aorta and red * showing the intimal flap in the descending aorta), (c) 3D-​MR angiogram of the same patient (black arrow showing the intimal flap), (d) Contrast-​enhanced MR angiography of the aorta in a sagittal view (MIP reconstruction) in a patient with a type B aortic dissection (red * showing the entry tear in the proximal descending aorta). TL = true lumen; FL = false lumen.

the dissection (z Video 51.4). In type A dissection, it is mandatory to include cine-​CMR sequences through the left ventricular outflow tract to rule out valvular regurgitation. Along with age, signs and/​or symptoms of organ malperfusion, clinical instability, fluid extravasation into the pericardium, and periaortic haematoma represent poor prognosis in the acute phase. After discharge, different variables have been associated with outcomes after long-​term follow-​up in type B dissection. They include aortic diameter >40 mm in acute phase [39], false lumen diameter

(a)

>22 mm [40], a wide and proximal entry tear [41], and partial false lumen thrombosis [42]. Although these variables stemmed from CT studies, they could also be assessed by CMR.

Intramural haematoma (IMH) Spontaneous acute IMH can be observed with no imaging features of intimal flap or penetrating atherosclerotic ulcer, and may be secondary to vasa vasorum rupture, the capillary network of the adventitia and media [43, 44]. However, IMH may

(b)

(c)

Fig. 51.8  Contrast-​enhanced MR

angiography in a patient with a type B aortic dissection with an entry tear distal to the left subclavian artery (black * at the level of the entry tear) in a sagittal view (a), coronal view (b), and axial view (c). The black arrows show the presence of partial thrombosis of the false lumen. TL = true lumen; FL = false lumen.

Diag n o si s of thor aci c aort i c di se ase s (a)

(b)

(c)

(d)

Fig. 51.9  T1-​weighted turbo spin echo in a sagittal view (a) and axial view (b and c) of three different patients with an intramural haematoma in the subacute

phase (images c and d correspond to the same patient). The arrows and the * show the presence of signal hyperintensity corresponding to the bleeding region. A fat suppression technique (c) is applied to differentiate the intramural haematoma from periaortic fat. Post-​contrast T1-​weighted image showing the absence of communication (black *) between the bleeding region and the aortic lumen (d).

also be secondary to imperceptible microscopic intimal tears with limited wall dissection in which the false lumen is completely thrombosed. IMH is associated with hypertension and tends to occur preferentially in older patients and disproportionately in the descending aorta [45, 46]. A classic double-​barrelled dissection in which the lumen is completely thrombosed at the time of initial imaging is very rare but indistinguishable from an IMH, and these conditions may have considerable overlap in natural history and require similar treatment [45, 46]. Although greater availability and rapidity favour the use of CT in acute diseases, CMR plays a major role in the diagnosis of IMH. The greater contrast among tissues offered by CMR often permits the depiction of small IMHs, which may go unnoticed on CT [43]. The typical finding is the presence of thickening of the aortic wall (semilunar or concentric) with a hyperintense signal in T1-​weighted black-​blood sequences (E Fig. 51.9). In the hyperacute phase, the haematoma shows an isointense signal in T1-​weighted images and a hyperintense signal in T2-​weighted images (E Fig. 51.10). From the first 24–​72 hours, the change from oxyhaemoglobin to methaemoglobin is responsible for a hyperintense signal in T1-​ and T2-​weighted images. Fat suppression techniques are crucial to differentiate periaortic fat from IMH (E Fig. 51.9c). Mural thrombi may present with semi-​lumen morphology that mimics

the morphology of IMH, rendering the differential diagnosis by CT or TEE difficult. This differentiation is easier by CMR since mural thrombosis shows a hypo-​or isointense signal in both T1-​ and T2-​weighted sequences. The evolution of IMH may result in resorption, aneurysm formation or dissection [47]. IMH may regress completely in 34% of patients, progress to aortic dissection in 12%, to aneurysm in 20% and to pseudoaneurysm in 24% (E Fig. 51.11). Given their wider field-​of-​view, CMR and CT are better than TEE for defining this dynamic evolution. Also, CMR offers the possibility of monitoring the evolution of intramural bleeding and depicting new asymptomatic intramural re-​bleeding episodes.

Penetrating atherosclerotic ulcer PAU is defined as an atherosclerotic lesion that penetrates the elastic lamina, usually leading to haematoma within the media, but also potentially to true dissection or rupture. The diagnosis of penetrating ulcer by CMR is based on visualization of a crater-​like ulcer located in the aortic wall. CMR is particularly suitable for depicting aortic ulcers together with the irregular aortic wall profile seen in diffuse atherosclerotic involvement. The aortic ulcer is easily recognized as contrast-​filled outpouching of variable extent with jagged edges (E Fig. 51.12). Black-​blood sequences

(a) (b)

Fig. 51.10  T2-​weighted turbo

spin-​echo images in a patient with an intramural haematoma in the hyperacute phase (first 48 hours). The images show the presence of a signal hyperintensity corresponding to the acute bleeding (arrow) in a sagittal view (a) and in an axial view (b).

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(b)

(c)

(d)

(e)

Fig. 51.11  Evolution of a patient with a type B intramural haematoma. Initially, the patient presented a localized dissection (ulcer-​like image or pseudoaneurysm) as seen in images (a), (b), and (c) (white and black arrows). At follow-​up, the patient progressed to a classical type B aortic dissection (d and e, red arrows).

may show disruption of the intima with extension of the ulcer to the thickened media that may be associated with IMH. It may be difficult to differentiate penetrating ulcer from the typical forms of dissection. The differential diagnosis should be established between arteriosclerotic ulcers that penetrate the middle layer and ulcer-​like images that develop from a localized dissection of an IMH that appears as a pseudoaneurysm located in the area of the former IMH (E Fig. 51.11).

(a)

(b)

(c)

(d)

The natural history of PAU is unknown and several evolutive possibilities have been described. Many patients with PAU do not need immediate aortic repair but do require close follow-​up with serial imaging studies (CMR/​CT) to document disease progression. Although many authors have documented the propensity of aortic ulcers to develop progressive aneurysmal dilatation and the possibility of spontaneous aortic rupture, the progression is usually slow. CMR may be helpful to show incidental and

(e)

(f)

Fig. 51.12  Penetrating atherosclerotic ulcer in a patient presenting with acute chest pain. (a) Axial SSFP single-​shot image showing the presence of a crater-​

like lesion in the aortic wall (arrows). The image also shows the presence of left pleural effusion (*). (b) Axial T1-​weighted image showing the presence of an outpunching lesion in the aortic wall associated to the presence of an isointense signal of the aortic wall compatible to the presence of an atherosclerotic plaque. (c) Fat suppression technique to exclude the presence of periaortic fat. (d) Same image after the administration of contrast. (e, f) Contrast-​enhanced MR angiography showing the penetrating atherosclerotic ulcer in the same patient in different projections (white arrows).

Diag n o si s of thor aci c aort i c di se ase s asymptomatic bleeding of aortic ulcers. Some aortic ulcers are an incidental finding, similar to saccular aneurysms, in these cases, size and enlargement are the only predictors of complications. The prognosis of the ulcer-​like images following an IMH or aortic dissection is variable. Thus, its presence in the acute phase has a poor prognosis owing to the high risk of aortic rupture (Hazard Ratio: 24.43). However, if they appear in the chronic phase, most of them evolve with slow aortic dilatation and without complications [48].

Acute aortic syndrome in blunt trauma Thoracic aortic injury is one of the leading causes of death in major blunt trauma and involves partial or total transection of the aortic wall [49]. The aortic segment subjected to the greatest strain by rapid deceleration forces is located just beyond the isthmus, thus, aortic rupture occurs at this site 90% of times. Other less common sites are the distal ascending aorta or distal segments of the descending aorta. The lesion is transverse, involves all or part of the aortic circumference and penetrates the aortic layers to various degrees with the formation of a false aneurysm. Intimal haemorrhage without any laceration has been described in pathological series but was not easily recognized in vivo before the advent of high-​resolution imaging modalities. Periaortic haemorrhage occurs irrespective of the type of lesion. The closed bore design and long examination time have been the main limitations of CMR in acute aortic diseases and trauma patients. The potential for CMR to detect the haemorrhagic components of a lesion by its high signal intensity is beneficial in trauma patients. On spin-​echo images in the sagittal plane, the longitudinal view of the thoracic aorta makes it possible to distinguish a partial lesion from a lesion encompassing the entire aortic circumference. This discrimination is of prognostic significance since a circumferential lesion may be more likely to rupture. The presence of periadventitial haematoma and/​or pleural and mediastinal haemorrhagic effusion may also be considered as a sign of instability. On the same sequence, the wide field-​of-​view of CMR provides a comprehensive evaluation of chest trauma such as lung contusion

(a)

(b)

and oedema, pleural effusion, and rib fractures. Furthermore, if delayed surgery is considered, CMR may be used to monitor thoracic and aortic lesions as it is non-​invasive and repeatable [50]. MRA provides an excellent display of the aortic lesion and its relationship with supra-​aortic vessels. However, it does not add any diagnostic value to spin-​echo CMR, and it cannot supply information on parietal lesions and haemorrhagic lesions outside the aortic wall.

Aortitis Inflammatory diseases of the aorta can be classified into two major subgroups: aortitis of non-​specific or unknown aetiology (Takayasu´s aortitis, Beçhet disease, giant cell aortitis, Kawasaki disease, ankylosing spondylitis), and specific aortitis, in which the aortitis is the consequence of an inflammatory disease of known origin (e.g. syphilitic aortitis). Relevant ethnic differences have been observed in the epidemiological distribution of non-​specific aortitis and they are more common in Asian countries. Typical findings are marked irregular thickening of the aortic wall along with fibrous lesions that are the results of the inflammatory process of the media which can lead to stenotic lesions (Takayasu´s disease), aneurysms of the aorta and its major branches, or aortic insufficiency because of aortic root dilation. The high spatial and contrast resolution offered by newer CMR techniques permit the assessment of the aortic wall, and CMR is included as a routine test in the work-​up of patients with vasculitis affecting large vessels, giant cell arteritis and Takayasu´s arteritis. Contrast spin echo in black-​blood sequences is useful to identify the wall thickening in aortitis of various causes. In the initial stages of Takayasu’s arteritis, short inversion-​ time inversion-​ recovery (STIR) and post-​contrast T1-​weighted sequences are particularly useful. Inflammatory changes in initial phases are reflected with contrast uptake and hyperintensity secondary to the wall oedema in STIR sequences (E Fig. 51.13). Active inflammatory disease appears as variable thickening of the aortic wall and delayed contrast-​enhancement after gadolinium administration can characterize the degree of inflammation in the aortic

(c)

Fig. 51.13  (a) Axial T1-​weighted turbo spin-​echo images in a patient with an acute aortitis showing the presence of an isointense concentric thickening of the

aortic wall (white arrows). (b) T2-​weigthed images in the same patient showing the presence of concentric signal hyperintensity of the aortic wall confirming the acute and inflammatory stage of the disease (white arrows). (c) Axial post-​contrast T1-​weighted images in a patient with a chronic aortitis in the descending aorta showing the presence of hyperenhancement of the aortic wall with a laminar intramural thrombus (yellow arrow).

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wall of patients with Takayasu’s arteritis [51]. In advanced stages of the disease, CE-​MRA can determine the presence of stenosis in the aorta and its main branches secondary to chronic fibrous alterations. Recently, it has been shown the capability of 18F-​FDG hybrid PET camera combined with CMR to depict early stages of Takayasu’s aortitis or to diagnose the presence of an infected aneurysm [52, 53]. Moreover, CMR can be useful in evaluating the response to medical treatment by depicting a decrease in arterial wall thickness.

Aortic coarctation Coarctation of the aorta causes a more or less severe stenosis at the junction of the aortic arch and descending aorta and may be focal or more diffuse. Pseudocoarctation resembles a true coarctation but is caused by aortic kinking just distal to the origin of the left subclavian artery. It is usually not flow-​limiting and therefore not associated with multiple collaterals. CE-​MRA is the most useful technique for evaluating stenoses of the thoracic aorta. Temporally resolved CE-​MRA can depict aortic stenoses, but it is particularly useful in haemodynamically significant lesions such as coarctation, where it demonstrates gradual filling of chest wall collaterals (E Fig. 51.14). PC CMR can be used to

(a)

Fig. 51.14  Contrast-​enhanced MR

angiography showing a patient with an haemodynamically significant aortic coarctation (arrow) associated with multiple collateral vessels: MIP reconstruction (a) and 3D volume rendering reconstruction (b).

measure velocity and flow, both proximal and distal to a stenosis, and helps assess the significance of a stenosis [54]. In patients with haemodynamically significant coarctation, an inversion in the aortic flow pattern has been observed with a higher flow in the distal thoracic descending aorta compared to the aortic flow precoarctation. CMR may be very useful in monitoring disease progression over time. However, it is important to obtain measurements in similar anatomical locations to produce accurate and consistent results. CMR is also well adapted for serial follow-​ up imaging after surgery of the aortic aorta with no radiation exposure.

Pitfalls and limitations The main limitations of CMR imaging include the low availability 24 hours per day, cost, patient claustrophobia, and the classical contraindications (pacemakers/​defibrillators, metallic ocular implants, and cerebral vascular clips). CMR is not contra-​ indicated in patients with mechanical prosthetic valves, but the valve may induce a signal void artefact which may preclude the study of the initial portion of the aorta. Big aortic stents often make the local study of the aorta impossible (mainly the cobalt or stainless steel ones). Although in some cases, depending on

(b)

RE F E RE N C E S the paramagnetic properties of the stent the evaluation is feasible (z Video 51.1). In acute aortic diseases, CMR is limited by lesser availability and is more time-​consuming. For unstable patients, TEE or CT are better options. The use of gadolinium

chelates is not possible in patients with severe renal insufficiency (clearance 60 mm for the ascending aorta and >70 mm for the descending aorta [14]. Although dissection may occur in patients with a

Table 52.2  Atherosclerotic plaque grades Grade I

Minimal intimal thickening

Grade II

Extensive intimal thickening

Grade III

Aortic atheroma

Grade IV

Protruding atheroma

Grade V

Mobile atheroma

Box 52.1  Causes of thoracic aortic aneurysm

Causes of thoracic aortic aneurysm Atherosclerosis Aortic dissection Medial degeneration (genetic) Marfan syndrome Ehlers–​Danlos syndrome Outside influences (acquired) Trauma Syphilis Mycosis (infection) Noninfective aortitis Rheumatic fever Rheumatoid arthritis Ankylosing spondylitis Giant cell arteritis Relapsing polychondritis Takayasu arteritis Reiter syndrome Systemic lupus erythematosus Scleroderma Psoriasis Ulcerative colitis Radiation Behçet disease Congenital aneurysm (rare) Source data from Moll FL, Powell JT, Fraedrich G, et al. Management of abdominal aortic aneurysms clinical practice guidelines of the European Society for Vascular Surgery. Eur J Vasc Endovasc Surg. 2011;41 Suppl 1:S1–​ S58. doi:10.1016/​j.ejvs.2010.09.011.

small aorta, the individual risk is very low. Current European Society of Cardiology (ESC) guidelines recommend interventions on ascending aortic aneurysms with maximal ascending aortic diameters of ≥55 mm for patients with no elastopathy. Lower thresholds are recommended for patients with Marfan syndrome or patients with bicuspid valve and risk factors (≥45 and ≥50 mm, respectively) [12]. Particularly important is to monitor the size of aneurysms with MSCT annually; accelerated annual growth can constitute an indication of surgery on its own [15]. Although thoracic aortic aneurysms are usually asymptomatic, they can produce symptoms by compressing adjacent structures when reaching significant aortic size. MSCT allows visualization of potential vulnerable structures such as superior vena cava (superior vena cava syndrome), airway compression resulting in stridor or dyspnoea, or recurrent laryngeal nerve or oesophageal compression causing hoarseness or dysphagia, respectively [16] (E Fig. 52.2). Abdominal aortic aneurysm (AAA)—​ almost exclusively infrarenal—​is usually defined as a diameter ≥30 mm. Although the main cause is degenerative, it is also commonly associated

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Fig. 52.2  Right-​sided aortic arch, aberrant left subclavian artery, and aneurysm at the origin of the aberrant artery (Kommerell aneurysm). Upper panel: Axial

MSCT images with contrast. Lower panel: volume rendered images. AA = aortic arch; KA = Kommerell aneurysm; LSA = origin of the aberrant left subclavian artery. Right-​sided aortic arch is a rare anatomical variant present in about 0.1% of the adult population and half of the cases are associated with an aberrant left subclavian artery. Aneurismal dilatation usually at Kommerell’s diverticulum may occur causing compression of adjoining structures.

with atherosclerotic disease. The reported average growth rate of AAAs between 30 and 55 mm ranges from 0.2 to 0.3 cm per year [17]. Similarly to thoracic aortic aneurysm, maximum size (>55 mm), symptoms, or fast growing (>10 mm/​year) are current indications for AAA intervention (E Fig. 52.3). Preoperative assessment of abdominal aneurysms includes the measurement of their maximal transverse perpendicular diameter and the relationship of the aneurysm to the renal arteries. Their lengths, as well as diameters, angulations, and tortuosity, are particularly important for endovascular aneurysm repair [12].

Inflammatory aortic diseases Aortitis is a general term that refers to a broad category of infectious or non-​infectious conditions in which there is abnormal inflammation of the aortic wall. The most common causes of aortitis are non-​infectious inflammatory vasculitis such as Takayasu arteritis and giant cell arteritis (GCA). It is

also seen in other collagen vascular disorders such as rheumatoid arthritis and ankylosing spondylitis. Infectious aortitis may be secondary to tuberculosis, syphilis, or infection due to Salmonella, Staphylococcus, mycobacteria or other bacterial or viral pathogens [18]. Imaging in general and MSCT in particular allows early diagnosis, identifying the pattern of aortic involvement and the presence aortic wall changes. Nuclear medicine imaging with fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is helpful in assessment of inflammatory activity and its combination with MSCT allows the evaluation of morphologic changes. Any FDG uptake in the aorta is considered abnormal, and in active aortitis, FDG uptake is higher in the aortic wall than in the liver [19, 20]. Given the limited spatial resolution of PET alone, PET imaging performed in conjunction with MSCT allows for more precise localization of inflammatory lesions. MSCT findings in Takayasu arteritis include concentric thickening of the vessel wall, thrombosis, stenosis, and occlusion (E Fig. 52.4). Other associated findings include vessel ectasia, aneurysms, and ulcers. Arterial wall calcification can develop in chronic

Acu te thor aci c sy n dro m e s

Fig. 52.3  Large infrarenal abdominal aortic aneurysm (AAA) of

9.6 × 10 cm., with signs of contained rupture (high density fluid and stranding of retroperitoneal fat).

cases, typically after several years of inflammatory involvement. Aortic wall calcification is typically linear and usually spares the ascending aorta. On the other hand, aortic involvement occurs in 15% of GCA patients usually manifests as annuloaortic ectasia or as an ascending aortic aneurysm that can extend into the aortic arch, which can lead to aortic dissection, or rupture. Aortic involvement can also manifest as aortic valve insufficiency, or AAA. MSCT can detect thickened aortic wall or luminal changes such as stenosis, occlusion, dilatation, aneurysm formation, calcification, and mural thrombi [21].

(a)

(b)

(c)

(d)

Acute thoracic syndromes Acute aortic syndromes (AAS) including thoracic aortic dissection (TAD), intramural haematoma (IMH), and penetrating atherosclerotic ulcer (PAU) are emergency conditions with similar clinical characteristics involving the aorta that requires accurate and prompt diagnosis and management (E Fig. 52.5). MSCT is the preferred modality for diagnosis and complete characterization of AAS because of its widespread availability, rapidity, excellent spatial resolution, and accuracy for ascending and descending aortic pathology.

Fig. 52.4  Concentric thickening

of the aortic wall in a patient with Takayasu arteritis. Significant thickening was found at the origin of the supra-​aortic trunks (a), aortic arch (b) and the proximal portion of the descending thoracic aorta and in the abdominal aorta distal to the celiac trunk (c and d).

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Dissection

Intramural haematoma

Penetrating aortic ulcer

Fig. 52.5  Acute aortic syndromes can have overlapping features that include dissection, penetrating aortic ulcer, and intramural hematoma. These three conditions can occur with overlapping clinical, radiological, and anatomic features.

Reproduced from Oderich GS, Kärkkäinen JM, Reed NR, Tenorio ER, Sandri GA. Penetrating Aortic Ulcer and Intramural Hematoma. Cardiovasc Intervent Radiol. 2019;42(3):321–​34. doi:10.1007/​s00270-​018-​2114-​x with permission from Springer Nature.

Aortic dissection (AD) AD is the most common AAS and defined by disruption of the medial layer provoked by intramural bleeding, resulting in separation of the aortic wall layers and subsequent formation a true and a false lumen separated by an intimo-​medial flap with or without communication [12, 22–​24]. In most cases, an intimal tear is the initiating process, causing an inflow of blood into the media. This process is followed either by an aortic rupture in the case of adventitial disruption or by a re-​entering into the aortic lumen through a second intimal tear.

There are two classifications of AD: De Bakey and Stanford. Both are based on the origin of the intimal tear and the extent of aortic involvement. The Stanford classification is the most often used in clinical routine and determines the treatment approach. Type A dissection involves the ascending aorta regardless of the origin of the intimal tear or the extent of the dissection (E Fig. 52.6) and requires urgent surgical repair. Type B dissection affects only the descending aorta and is usually managed conservatively with antihypertensive medication. It may be complicated by dilatation and rupture of the false lumen,

Fig. 52.6  Type A and B aortic dissection in a patient with a previous Bentall’s Procedure. Extensive dissection of thoracoabdominal aorta that originates immediately distal to the aortic valve in the ascending aorta, and that extends distally to the iliac arteries.

Acu te thor aci c sy n dro m e s end-​organ ischaemia, and progression to type A dissection. Complicated type B dissection can be managed by endovascular repair. MSCT is the most common imaging modality in AD with a sensitivity of 95% for AD [24]. The main finding on contrast-​ enhanced images is the intimal flap separating the true and false lumens, which is observed in around 70% of the studies. The false lumen is usually larger in diameter, has slower flow, and may contain thrombus; the true lumen can be identified by its continuity with an unaffected segment of the aorta. The convex face of the intimal flap is usually towards the false lumen that surrounds the true lumen. In type A AD, the false lumen is most commonly located along the right anterolateral wall of the ascending aorta and extends distally, in a spiral fashion, along the left posterolateral wall of the descending aorta. In most cases, the lumen that extends more caudally is the true lumen. In addition, MSCT allows a comprehensive assessment of the entire aorta, including aortic diameters, shape, and the extent of aortic involvement. It can detect the entry point, signs of rupture, extension into the aortic valve or aortic branches, presence and location of true and false lumen, involvement of vital vasculature, and distance from the intimal tear to the vital vascular branches. Particularly important is the ability of MSCT to detect signs of emergency and signs of ongoing aortic penetration or rupture including periaortic haematoma, mediastinal bleeding, pericardial effusion, and pleural effusion. Acute and chronic haematoma can be differentiated based on differences in Hounsfield density. Multiplanar reconstruction images are a particular advantage of MSCT imaging, determining the extent of involvement and the involvement of aortic branch vessels.

Intramural haematoma (IMH) Intramural haematoma occurs after bleeding of the vasa vasorum in the medial layer of the aorta without intimal tear. The resulting haematoma can lead to infarction of the aortic wall, which may contribute to the development of an AD or aortic aneurysm. IMH is diagnosed in the presence of a circular or crescent-​shaped thickened aorta (>5 mm) in the absence of detectable blood flow (and therefore absence of contrast) [25, 26]. (a)

Unenhanced MSCT acquisitions are crucial for the diagnosis and allow the differential diagnosis with an atherosclerotic thrombus. A high-​attenuation crescentic thickening of the aortic wall, extending in a longitudinal, non-​spiral fashion, with no enhancement after contrast is the hallmark of this entity (E Fig. 52.7). The aortic lumen is commonly not affected and no intimal flap is seen after contrast. However, given the similarities with AD, IMH are also categorized according to the Stanford classification.

Penetrating atherosclerotic ulcer PAU is an ulceration of an atheromatous plaque that disrupts the intimal layer of the aortic wall with subsequent extension of blood into the media [27]. PAUs can remain stable or enlarge and develop aortic aneurysms (E Fig. 52.8). Progression of the ulcerative process may lead to IMH, or rarely progress into AD, pseudoaneurysm, or even aortic rupture if the ulcer breaks through the adventitia. Contrast-​enhanced MSCT shows typically a localized ulceration penetrating through the aortic intima in the mid-​to distal third of the descending thoracic aorta. PAU can be multiple, and vary greatly in size and depth within the vessel wall. Focal thickening or high attenuation in the adjacent aortic wall suggests associated IMH.

Blunt and iatrogenic aortic injury MSCT is the modality of choice for the assessment of thoracic aorta emergencies after blunt and iatrogenic trauma. These include incomplete and complete aortic rupture; traumatic or iatrogenic AD; traumatic intramural haematoma or pseudoaneurysm after endovascular repair. Optimized protocols are essential in maximizing the yield of diagnostic information for the most complete and accurate assessment. Thin collimation and triggered intravenous contrast material injection is absolutely mandatory. Blunt traumatic thoracic aortic injuries are commonly located at the aortic isthmus [28]. Clinical practice guidelines from the Society of vascular surgery classifies blunt aortic injuries in four grades based on the severity (E Fig. 52.9) [29, 30]. These include: grade 1, intimal tear; grade 2, intramural haematoma; grade 3,

(b)

Fig. 52.7  Intramural haematoma.

Non-​contrast (left) and contrast (right) axial CT images show a high density crescent-​shaped thickened descending aorta (8 mm) and the absence of contrast outlying to intimal calcifications.

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Fig. 52.8  Saccular dilatation with thrombosis in

the anterior wall of the descending thoracic aorta, which correspond to a pseudoaneurysm as the evolution of a penetrating ulcer.

aortic pseudoaneurysm with transection of the aortic wall; and grade 4, free aortic rupture. While grade I can be managed conservatively with careful monitoring, surgery or endovascular treatment is indicated in grade II, III, and IV. Evidence showed that most grade I injuries healed spontaneously, although close follow-​ up is necessary to detect late aortic related complications [29].

Fig. 52.9  Classification system for traumatic aortic injury.

Reproduced from Azizzadeh A, Keyhani K, Miller CC 3rd, Coogan SM, Safi HJ, Estrera AL. Blunt traumatic aortic injury: initial experience with endovascular repair. J Vasc Surg. 2009;49(6):1403–​8. doi:10.1016/​j.jvs.2009.02.234 with permission from Elsevier.

Iatrogenic AD may occur in the setting of catheter-​ based coronary procedures, cardiac surgery, as a complication of endovascular treatment of aortic coarctation, aortic endografting, peripheral interventions, intra-​aortic balloon counterpulsation, and during transcatheter aortic valve implantation. Classical intimal flaps or patent false lumen are visualized less often suggesting

L i m i tati on s of   M S C T that iatrogenic AD may occur in the form of IMH and produces a more localized injury [31]. Resources of the International Registry of Aortic Dissection showed aortic iatrogenic AD in 5% of all patients included with aortic dissection, 76% had Stanford type A, and 24% had type B. Proximal iatrogenic AD most often followed cardiac surgical procedures and distal dissections were more likely to follow cardiac catheterization. The diagnosis of iatrogenic AD is usually challenging given its atypical presentation and the relative lack of classic signs of AD on imaging studies. The mortality for iatrogenic AD is high, and in cases of type B iatrogenic AD, may exceed that of spontaneous dissection.

immediately, type 4 endoleaks are self-​limited and require no treatment, and commonly resolve with normalization of the patient’s coagulation status. The management of type 2 endoleak is controversial, and requires individualized assessment. Lastly, aneurysm expansion without endoleak is known as endotension or type 5 endoleak. The exact cause of endotension is unknown. Current recommendations in postoperative imaging include predischarge or 1-​month postoperative assessment after thoracic aortic surgery, followed by reimaging at progressively longer intervals with the aim to confirm stability and efficacy of surgical or interventional techniques.

Postoperative imaging MSCT is essential in the follow-​up of patients after emergent or elective thoracic aortic intervention or surgery. Interpretation of MSCT findings can be confusing and knowledge of surgical details is of paramount importance prior to interpretation. Protocols should be tailored according to the type of surgery performed. Complications that should be detected include haematoma, pseudoaneurysm, mediastinal fluid collection, pneumomediastinum, grafts dehiscence or infection, and progression of residual aneurysm or dissection, as well as stent complications or deformation in cases of thoracic endovascular aortic repair [32, 33]. Endoleak is a unique complication of endovascular repair and defined as the presence of contrast enhancement outside the stent-​graft. Depending on the source of blood flow there are four types of endoleaks: type I, leak at the attachment site; type II, leak from a branch artery; type III, graft defect; and type IV, graft porosity (E Fig. 52.10). Identification of the correct type of endoleak has important treatment implications. While type 1 and type 3 endoleaks are repaired

Limitations of MSCT Although MSCT holds a high diagnostic accuracy for aorta pathology when applying ECG triggering and slice thickness below 2 mm, theses protocols are more time consuming and not always applied. In non-​triggered MSCT data sets, small AD and PAU may be unnoticed due to motion artefacts. In critical emergency setting, motion artefacts may simulate increased wall thickness or mimic a dissection flap. On the other hand, MSCT can produce false negative results in AASs when the aorta is inadequately opacified. This may occur if the contrast bolus is administered too slowly or if the patient has low cardiac output. One major limitation of MSCT is the potential for development of contrast-​ induced nephropathy with iodine-​ based contrast agents. In patients with high risk of nephropathy, hydration, or an alternative imaging modality (often transoesophageal echocardiography (TEE) in acute setting or MRI in stable patients) should be considered [34].

Fig. 52.10  Infrarenal abdominal aortic aneurysm treated by aortoiliac endoprosthesis. A small type II endoleak at the lumbar artery is observed in the posterior portion of the aneurysm.

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References 1. Aronberg DJ, Glazer HS, Madsen K, Sagel SS. Normal thoracic aortic diameters by computed tomography. J Comput Assist Tomogr 1984; 8: 247–​50. 2. Hager A, Kaemmerer H, Rapp-​Bernhardt U, et al. Diameters of the thoracic aorta throughout life as measured with helical computed tomography. J Thorac Cardiovasc Surg 2002; 123: 1060–​6. 3. Kaplan S, Aronow WS, Lai H, et al. Prevalence of an increased ascending and descending thoracic aorta diameter diagnosed by multislice cardiac computed tomography in men versus women and in persons aged 23 to 50 years, 51 to 65 years, 66 to 80 years, and 81 to 88 years. Am J Cardiol 2007; 100: 1598–​9. 4. Lin FY, Devereux RB, Roman MJ, et al. Assessment of the thoracic aorta by multidetector computed tomography: age-​and sex-​specific reference values in adults without evident cardiovascular disease. J Cardiovasc Comput Tomogr 2008; 2: 298–​308. 5. Mao SS, Ahmadi N, Shah B, et al. Normal thoracic aorta diameter on cardiac computed tomography in healthy asymptomatic adults: impact of age and gender. Acad Radiol 2008; 15: 827–​34. 6. Wolak A, Gransar H, Thomson LE, et al. Aortic size assessment by noncontrast cardiac computed tomography: normal limits by age, gender, and body surface area. JACC Cardiovasc Imaging 2008; 1:  200–​9. 7. Kälsch H, Lehmann N, Möhlenkamp S, et al. Body-​surface adjusted aortic reference diameters for improved identification of patients with thoracic aortic aneurysms: results from the population based Heinz Nixdorf Recall study. Int J Cardiol 2013; 163: 72–​8. 8. Ribakove GH, Katz ES, Galloway AC, et al. Surgical implications of transesophageal echocardiography to grade the atheromatous aortic arch. Ann Thorac Surg 1992; 53: 758–​61; discussion 762–​3. 9. Gutschow SE, Walker CM, Martinez-​ Jimenez S, Rosado-​ de-​ Christenson ML, Stowell J, Kunin JR. Emerging concepts in intramural hematoma imaging. Radiographics 2016; 36: 660–​74. 10. Vardhanabhuti V, Nicol E, Morgan-​Hughes G, et al. Recommendations for accurate CT diagnosis of suspected acute aortic syndrome (AAS), on behalf of the British Society of Cardiovascular Imaging (BSCI)/​ British Society of Cardiovascular CT (BSCCT). Br J Radiol 2016; 89: 20150705. 11. ACCF/​AHA/​AATS/​ACR/​ASA/​SCA/​SCAI/​SIR/​STS/​SVM guidelines for the diagnosis and management of patients with thoracic aortic disease: a report of the American College of Cardiology Foundation/​American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. J Am Coll Cardiol 2010; 55: e27–​129. 12. Erbel R, Aboyans V, Boileau C, et al. 2014 ESC guidelines on the diagnosis and treatment of aortic diseases: document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J 2014; 35: 2873–​926. 13. Bickerstaff LK, Pairolero PC, Hollier LH, et al. Thoracic aortic aneurysms: a population-​based study. Surgery 1982; 92: 1103–​8.

14. Agarwal PP1, Chughtai A, Matzinger FR, Kazerooni EA. Multidetector CT of thoracic aortic aneurysms. Radiographics 2009; 29: 537–​52. 15. Coady MA, Rizzo JA, Hammond GL, et al. What is the appropriate size criterion for resection of thoracic aortic aneurysms? J Thorac Cardiovasc Surg 1997; 113: 476–​91. 16. Posniak HV, Olson MC, Demos TC, Benjoya RA, Marsan RE. CT of thoracic aortic aneurysms. RadioGraphics 1990; 10: 839–​55. 17. Moll FL, Powell JT, Fraedrich G, et al. Management of abdominal aortic aneurysms clinical practice guidelines of the European Society for Vascular Surgery. Eur J Vasc Endovasc Surg 2011; 41 Suppl 1: S1–​S58. 18. Restrepo CS, Ocazionez D, Suri R, Vargas D. Aortitis: imaging spectrum of the infectious and inflammatory conditions of the aorta. Radiographics 2011; 31: 435–​51. 19. Hartlage GR, Palios J, Barron BJ, et al. Multimodality imaging of aortitis. J Am Coll Cardiol Img 2014; 7: 605–​19. 20. Hayashida T, Sueyoshi E, Sakamoto I, Uetani M, Chiba K. PET features of aortic diseases. AJR Am J Roentgenol 2010; 195: 229–​33. 21. Bau JL, Ly JQ, Borstad GC, Lusk JD, Seay TM, Beall DP. Giant cell arteritis. AJR Am J Roentgenol 2003; 181: 742. 22. Nienaber CA, Eagle KA. Aortic dissection: new frontiers in diagnosis and management. Part I: from etiology to diagnostic strategies. Circulation 2003; 108: 628e35. 23. Sommer T, Fehske W, Holzknecht N, et al. Aortic dissection: a comparative study of diagnosis with spiral CT, multiplanar transesophageal echocardiography, and MR imaging. Radiology 1996; 199: 347–​52. 24. Bhave NM, Nienaber CA, Clough RE, Eagle KA. Multimodality imaging of thoracic aortic diseases in adults. JACC Cardiovasc Imaging 2018; 11: 902–​19. 25. Evangelista A, Mukherjee D, Mehta RH, et al. Acute intramural hematoma of the aorta: a mystery in evolution. Circulation 2005; 111: 1063–​70. 26. Song JK. Diagnosis of aortic intramural haematoma. Heart 2004; 90: 368–​71. 27. Stanson AW, Kazmier FJ, Hollier LH, et al. Penetrating atherosclerotic ulcers of the thoracic aorta: natural history and clinicopathologic correlations. Ann Vasc Surg 1986; 1: 15e23. 28. Neschis DG, Scalea TM, Flinn WR, Griffith BP. Blunt aortic injury. N Engl J Med 2008; 359: 1708–​16. 29. Azizzadeh A1, Keyhani K, Miller CC 3rd, Coogan SM, Safi HJ, Estrera AL. Blunt traumatic aortic injury: initial experience with endovascular repair. J Vasc Surg 2009; 49: 1403–​8. 30. Lee WA, Matsumura JS, Mitchell RS, et al. Endovascular repair of traumatic thoracic aortic injury: clinical practice guidelines of the Society for Vascular Surgery. J Vasc Surg 2011; 53: 187–​92. 31. Januzzi JL, Sabatine MS, Eagle KA, et al. Iatrogenic aortic dissection. Am J Cardiol 2002; 89: 623–​6. 32. Latson LA Jr., DeAnda A Jr., Ko JP. Imaging of the postsurgical thoracic aorta: a state-​of-​the art review. J Thorac Imaging 2017; 32: 1–​25. 33. Prescott-​Focht JA, Martinez-​Jimenez S, Hurwitz LM, et al. Ascending thoracic aorta: postoperative imaging evaluation. Radiographics 2013; 33: 73–​85. 34. Wichmann JL, Katzberg RW, Litwin SE, et al. Contrast-​induced nephropathy. Circulation 2015; 132: 1931–​6.

SECTION 10

Adult congenital heart disease 53 The role of echocardiography in adult congenital heart disease  Lindsay A. Smith, Mark K. Friedberg, and Luc Mertens

54 The role of CMR and MSCT 

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Giovanni Di Salvo and Francesca R. Pluchinotta

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The role of echocardiography in adult congenital heart disease Lindsay A. Smith, Mark K. Friedberg, and Luc Mertens Contents

Introduction  783 Overview of the main non-​invasive imaging modalities  783 Describing abnormal cardiovascular connections  784 The role of echocardiography in different congenital defects  784

Atrial septal defects (ASD)  784 Ventricular septal defects (VSDs)  786 Atrioventricular septal defects (AVSDs)  787 Patent ductus arteriosus  789 Coarctation of the aorta  790 Right ventricular outflow tract obstruction (RVOTO)  791 Left ventricular outflow tract obstruction  792 Ebstein’s anomaly  793 Congenital mitral valve anomalies  794 Tetralogy of Fallot and tetralogy of Fallot with pulmonary atresia  795 Transposition of the great arteries  797 Congenitally corrected transposition of the great arteries  799 The functionally univentricular heart  801 Eisenmenger syndrome  803

Special topics in adult congenital imaging  804

Echocardiography in the pregnant woman with congenital heart disease  804 Echocardiography in patients with infective endocarditis and congenital heart disease  805 Tissue Doppler, strain, and strain rate in congenital heart disease  805 Three-​dimensional echocardiography in congenital heart disease  805 Stress echocardiography in patients with congenital heart disease  805

Acknowledgement  805

Introduction Congenital malformations of the heart affect at least 1% of newborn infants. Without intervention, the prognosis for more complex forms is poor. Over the last few decades advances in paediatric cardiology and cardiac surgery have significantly improved patient management, and the majority of patients now survive into adulthood [1–​3]. This has led to new challenges as increasing numbers of adult patients with congenital heart disease transition into the care of adult cardiac services. Caring for these patients requires expert knowledge and a new subspecialty of adult congenital heart disease (CHD) has emerged. This patient population also has specific imaging requirements due to variability in morphology and haemodynamics.

Overview of the main non-​invasive imaging modalities The different non-​invasive modalities are, to a large extent, complementary. More than one modality is likely to be needed to address all the relevant clinical questions, particularly in the more complex cases. Chest  X-​ray (postero-​anterior ± lateral) provides an inclusive overview of the heart, mediastinum, pulmonary vessels, lung fields, and thoracic skeleton. It remains a valuable and inexpensive modality, with only a low dose of ionizing radiation, for the serial comparison of heart size, pulmonary vascularity, and peripheral lung fields in adults with CHD. Transthoracic echocardiography (TTE) is generally the first-​ line cardiovascular imaging modality because of its convenience, availability, real-​time acquisition, safety, and relatively modest cost. Its usefulness is, however, operator dependent, particularly in adults with CHD. Limited echocardiographic acoustic windows and the suboptimal penetration of ultrasound represent important limitations in adults after cardiovascular surgery. Transoesophageal echocardiography (TOE) has the advantage of clear access to more posterior parts of the heart, particularly for 3D visualizations of valves and the atrial septum. A disadvantage, however, is its invasive nature, generally requiring sedation or anaesthesia, making it less acceptable than cardiac magnetic resonance (CMR) for serial investigation. The field of view provided by TOE also is relatively narrow, with limited access to extracardiac structures, and the alignment of the Doppler beam with unusually oriented flow jets can be challenging. Perioperative TOE is an essential tool and is used

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routinely in the operating room for assessing the surgical result immediately after cardiopulmonary bypass. TOE is also used for guiding interventional procedures in the cardiac catheterization laboratory (e.g. for interventional closure of atrial septal defects). Cardiovascular magnetic resonance (CMR) is not restricted by body size or poor acoustic windows and is versatile, offering a repertoire of velocity mapping and tissue contrast options, without any ionizing radiation. CMR is widely regarded as the gold standard for measurements of right as well as left ventricular volumes, although analysis takes time and requires rigorously consistent methods of acquisition and measurement that may be hard to maintain in practice. It also provides flow quantification and tissue characterization, which can be important in adults with CHD. Multislice computed tomography (MSCT) also offers robust spatial localization, plus excellent spatial resolution in much shorter investigation times than CMR. It is well suited for imaging the epicardial coronary arteries and aortopulmonary collateral arteries, and for the investigation of parenchymal lung disease, if present. ECG-​gated cine MSCT allows measurements of biventricular size and function, albeit at a lower temporal resolution than CMR, and subject to adequate opacification of the intraventricular blood volumes. In patients with a pacemaker or ICD, CT provides an alternative to CMR. The main drawback of MSCT is exposure to ionizing radiation, albeit at lower dose with advancing technology, and the need of contrast media. Other drawbacks compared with CMR include less versatile tissue contrast and an inferior ability to evaluate cardiovascular physiology. The role of CMR and MSCT in adult CHD is described in more detail in Chapter 54 of this textbook.

Describing abnormal cardiovascular connections For the description of anatomy a common methodology can be used by all imaging techniques. This is called the segmental approach [4]‌. The heart is viewed as consisting of certain segments (the systemic and pulmonary veins, the atria, the ventricles, and the great vessels) which are defined by unique morphological characteristics. The segments need to be identified and the connections between the segments are to be described. These are the venoatrial connections, the atrioventricular connections, and the ventriculoarterial connections. Segmental analysis begins by defining the cardiac position and atrial arrangement (situs). The cardiac position may be levocardia, dextrocardia, or mesocardia. The atrial situs is ‘usual’ (situs solitus, i.e. a right atrium (RA) on the right and a left atrium (LA) on the left), or ‘inverted’ (situs inversus) or there can be bilateral duplication of one type of atrium known as right or left atrial ‘isomerism’. Isomerism is generally associated with accompanying malformations. Atrioventricular (AV) and ventriculoarterial connections are described as concordant (e.g. RA to right ventricle [RV], or

left ventricle [LV] to aorta), discordant [e.g. LA to RV], double inlet [e.g. double inlet LV] or single inlet [left AV-​valve atresia]. This requires identification of the ventricular chambers as morphological left or right ventricles, which is based on unique morphological characteristics for each ventricle. A RV typically has coarser apical trabeculations, has a tricuspid valve at the inlet, has a moderator band and the inlet and outlet are separated by an infundibulum. Afterwards the great vessels are identified and the ventriculoarterial connections are described. These connections can be concordant (normal), discordant (transposition of the great arteries), double outlet (double outlet RV) or single outlet (pulmonary atresia, common arterial trunk). Finally communications between the left and right side need to be described (ventricular septal defect, VSD; atrial septal defect, ASD; patent ductus arteriosus, PDA).

The role of echocardiography in different congenital defects Atrial septal defects (ASD) ASDs are common also in the adult population. When diagnosing patients with ASDs, the following questions should be addressed:

Type and location of the ASD ◆ Secundum ASD (70%). The defect is localized centrally in the interatrial septum (E Fig. 53.1, z Video 53.1a and 53.1b). There can be multiple defects and the defect can be fenestrated. ◆ Primum ASD (11%). This belongs to the spectrum of atrioventricular septal defects. This is always associated with an abnormal left atrioventricular valve (‘cleft’ AV valve) (E Fig. 53.2, z Video 53.2a and 53.2b). ◆ Sinus venosus ASD (SVC 5.3–​10%, IVC 2%). This defect is located outside the limbus of the fossa ovalis, on the right septal surface adjacent to the drainage site of the superior (or inferior) vena cava (E Fig. 53.3, z Video 53.3). This is commonly associated with partially anomalous venous return of the right upper pulmonary vein. ◆ Coronary sinus ASD. This defect is in the wall that separates the coronary sinus from the left atrium (LA). It may be fenestrated or completely absent. An enlarged coronary sinus with a drop out between the LA and the coronary sinus is seen. This is best visualized in a posteriorly tilted four-​chamber view (E Fig. 53.4).

Haemodynamic effects The atrial left-​to-​right (L→R) shunt can cause right heart dilatation and can be associated with pulmonary hypertension. Signs of a haemodynamically significant ASD are: ◆ RA and RV dilatation. ◆ Abnormal ‘paradoxical’ septal motion. ◆ Elevated RV pressure (rare) ◆ The right to left (L→R) shunt can be quantified using the continuity equation (RV outflow tract VTI × RV outflow tract area/​

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts

Fig. 53.1  Large secundum ASD. There is a large central defect with secondary right atrial and right ventricular dilatation. The arrow points to the secundum ASD. The colour Doppler image on the right shows the left-​to-​right shunt through the ASD (arrow).

RA = right atrium; RV = right ventricle; LA = left atrium; LV = left ventricle.

Fig. 53.2  Large primum defect. The defect is located low in the

atrial septum just above the atrioventricular junction (arrow). The left and right AV valves are inserted at the same level and this is associated with abnormal left AV valve anatomy (‘cleft’ mitral valve). The right atrium and right ventricle are dilated. RA = right atrium; RV = right ventricle; LA = left atrium; LV = left ventricle.

Fig. 53.3  Sinus venosus defect. Subcostal view on the atrial septum (sagittal plane) A defect is noted in the superior part of the atrial septum (arrow). Typically there is overriding of the superior vena cava over the defect. There is a left-​to-​right shunt caused by the defect as shown on the colour image.

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The role of ech o cardio gra phy i n a du lt c on g en i ta l hea rt di sease ◆ Residual RA and RV dilatation ◆ Presence of pulmonary hypertension (PHT) ◆ AV-​valve regurgitation (especially after ASD primum repair)

Role of other imaging techniques Generally ASDs can be imaged fully using transthoracic echocardiography but in case of poor transthoracic windows, TOE is a very useful additional diagnostic technique. In case there is still uncertainty regarding the location (especially sinus venosus defects can be difficult to image by echocardiography in adults), or associated congenital abnormalities (particularly pulmonary vein abnormalities), CMR can be performed. Apart from the detailed anatomical imaging, CMR also allows a more accurate quantification of the systemic and pulmonary blood flow and calculation of Qp/​Qs, which is helpful for therapeutic decision-​making. Fig. 53.4  Coronary sinus ASD. This is a posteriorly directed apical

four-​chamber view. In this view a defect is shown in the area where the coronary sinus drains into the right atrium (arrow) with a left-​to-​right shunt from the left atrium (LA) through the coronary sinus into the right atrium (RA).

LVOT VTI × LVOT area) and a Qp:Qs > 1.5:1 is generally considered to be haemodynamically significant.

Ventricular septal defects (VSDs) In the newborn period, VSDs are one of the most common structural abnormalities diagnosed due to the high prevalence of small muscular VSDs in this population. As most of the small muscular defects close spontaneously and since large defects are treated surgically or percutaneously during childhood, VSDs are less common in the adult population.

Associated anomalies

The type and location of the VSD

A full segmental analysis needs to be performed as nearly any congenital anomaly can be associated with an ASD [5]‌. It is important to exclude pulmonary venous anomalies and interrupted inferior vena cava (IVC) before interventional closure of secundum defects. Most ASDs can be diagnosed using TTE. However, if right heart dilatation is found without identifying an ASD and without another cause, additional imaging including TOE or CMR is indicated to exclude a sinus venosus defect or anomalous pulmonary venous connections. Imaging is important during interventional closure of secundum ASDs. Currently, interventional closure is monitored either by TOE or by intracardiac echocardiography (ICE) [6]‌. Before device closure, adequacy of the ASD rims needs to be defined. Three-​dimensional echocardiography (3DE) allows an en-​ face view of the defect with a more accurate assessment of its size and morphology as well as the morphology of surrounding structures [7, 8].

◆ Perimembranous VSDs (60%) are localized in the membranous part of the septum and are characterized by fibrous continuity between the leaflets of the atrioventricular and arterial valve (E Figs. 53.5a and 53.5b, z Video 53.4a–​c). These defects may have inlet, trabecular, or outlet extensions. Anterior deviation of the outlet part of the septum can cause RV outflow tract obstruction (tetralogy of Fallot). Posterior deviation can cause LV outflow tract obstruction and can be associated with aortic arch anomalies (coarctation, interrupted aortic arch). ◆ Muscular VSDs (20%) are localized in the muscular septum. The muscular VSDs can be divided into the inlet, trabecular, or outlet types. There may occasionally be multiple defects. ◆ Doubly committed VSDs (5%) are localized just below the aortic and pulmonary valve and are characterized by fibrous continuity between the aortic and pulmonary valve (z Videos 53.5 and 53.6).

Imaging post surgery or intervention

◆ The size of the VSD should be measured in at least two dimensions. A VSD is small (10 mm). 3DE by allowing an en-​face visualization of the defect allows an accurate assessment of its size and morphology [9]‌. ◆ The L→R shunt can cause LA and LV dilatation. LA size, volume, and LV dimensions should be measured. There can be associated secondary mitral regurgitation due to LV dilatation. Associated structural abnormalities of the mitral valve are possible and should always be excluded.

Post surgery or intervention, echocardiographic follow-​up should focus on the following aspects: ◆ Residual atrial shunt through the patch/​device ◆ Position of the patch or device relative to other cardiac structures ◆ Complications related to device implantation, e.g. erosion of the aorta or atrial roof, thrombosis, infectious endocarditis, and device embolization

Assessment of defect size and haemodynamic significance

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts (a)

(b)

Fig. 53.5  (a) Perimembranous VSD as shown on a parasternal short-​axis view (arrow). The size is measured from this view. Typically the VSD is adjacent to the septal leaflet of the tricuspid valve. There is fibrous continuity between the aortic and tricuspid valve. (b) Perimembranous VSD. Colour flow demonstrates left-​to-​right shunting during systole (arrow).

◆ A VSD can be unrestrictive (with no significant pressure difference between both ventricles) or restrictive due to small size or tissue partially covering the VSD. ◆ A VSD can be associated with PHT. RV pressures should be assessed based on calculating the VSD pressure Doppler gradient or tricuspid regurgitant jet. Obstructive PHT can develop and result in R→L shunting across the VSD (Eisenmenger syndrome). ◆ The shunt can be calculated and a Qp:Qs >1.5:1 is considered as haemodynamically significant.

Associated anomalies Any congenital heart defect can be associated with a VSD. A full segmental analysis is therefore crucial. Commonly associated lesions are: ◆ Prolapse of the right coronary leaflet with progressive AR. ◆ Development of double chambered RV due to the presence of hypertrophic RV muscle bands. ◆ Development of LV outflow tract obstruction due to the development of a fibromuscular ridge or subaortic membrane, or due to the presence of posterior malalignment of the outlet septum. ◆ Anterior malalignment of the outlet septum can cause right ventricular outflow tract obstruction and aortic override (tetralogy of Fallot).

Imaging post surgery or interventions Most large VSDs will have been surgically closed during childhood. Percutaneous device closure of certain perimembranous and muscular VSDs is possible. Post-​surgical or device closure of a VSD, the following needs to be assessed: ◆ Residual VSDs due to patch leaks or additional VSDs ◆ The development of subaortic stenosis (membrane or fibromus­ cular ridge)

◆ The development of right ventricular muscle bundles causing right ventricular outflow tract obstruction ◆ Aortic regurgitation ◆ Tricuspid regurgitation (after perimembranous VSD closure), pulmonary regurgitation (after surgical closure of doubly committed VSD) ◆ Residual PHT

Role of other imaging techniques Most VSDs can be imaged using TTE. Rarely, TOE or other imaging modalities may be indicated. CMR can help quantify the Qp/​QS. Where there is uncertainty regarding the pulmonary vascular resistance or the presence of obstructive PHT, cardiac catheterization may be indicated.

Atrioventricular septal defects (AVSDs) Most AVSDs are diagnosed and will have been treated surgically in childhood. In adulthood, unoperated AVSDs with large ventricular components are associated with obstructive PHT (Eisenmenger syndrome). Isolated septum primum septum defects or intermediate AVSDs can be diagnosed in adulthood.

Types of AVSDs and morphologic description The essential morphological feature of an AVSD is the presence of a common atrioventricular (AV) junction with a common AV valve at the entrance of both ventricles [10, 11]. When imaging, the following features are important: ◆ Variable shunting across the AVSD. Different relationships between the bridging leaflets and the atrial and ventricular septal components determine different levels of shunting. In a complete defect, shunting is present at the level of the atrial septum (primum defect) and the inlet ventricular septum (E Fig. 53.6a, z Video 53.7a). If the bridging leaflets attach

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(a)

(b)

Fig. 53.6  (a) Complete atrioventricular septal defect. There is a single AV valve at the entrance of both ventricles. There is a large atrial primum component

(upper arrow) and a large inlet ventricular septum defect (lower arrow). There is a single AV valve at the entrance of both ventricles. (b) Subcostal ‘en-​face’ view on the AV valve. There is a single AV valve at the inlet of both ventricles. This valve has five leaflets: superior bridging leaflet (SBL), mural leaflet (ML), inferior bridging leaflet (IBL), right anterior leaflet (RAL), right inferior leaflet (RIL).

to the crest on the interventricular septum, they can close the VSD, and shunting can be present only at atrial level (primum defect). If the bridging leaflets are attached to the underside of the atrial septum, shunting can only be present at the ventricular level (inlet VSD). The bridging leaflets can close all septal defects resulting in a common AV junction with no atrial or ventricular communication (E Fig. 53.4). ◆ The common AV valve at the entrance of the ventricles is abnormal and is made up of five leaflets (E Fig. 53.6b, z Video 53.7b). It differs from a normal mitral and tricuspid valve. There is a variable degree of functional AV-​valve abnormalities associated with this lesion. This is mainly left or right AV-​valve regurgitation with valve stenosis being more uncommon. Three-​ dimensional echocardiography can be helpful in defining the AV-​valve morphology and determining the mechanisms of AV-​ valve regurgitation. ◆ The left ventricular outflow tract (LVOT) is elongated in the parasternal long axis. This is due to the presence of a single AV junction and unwedging of the aorta. LVOT obstruction can be present. ◆ Most defects have balanced ventricular chambers with dilatation of the RV mainly related to the atrial shunt. Unbalanced AVSD with RV or LV dominance can be present, however.

◆ AV-​valve regurgitation severity needs to be assessed and the mechanism described. ◆ If uncorrected, AVSD with large VSD components will give rise to obstructive PHT and Eisenmenger syndrome.

Haemodynamic assessment

◆ Residual atrial and/​or ventricular shunts. ◆ Left and right AV-​valve regurgitation or stenosis. Left AV-​valve regurgitation is common and often is due to the presence of a residual ‘cleft’. Other mechanisms related to AV-​valve dysplasia may be present. The description of the severity and associated AV-​ valve stenosis is important. Three-​ dimensional

◆ Variable degrees of atrial and/​or ventricular shunting can be present. These shunts can result in atrial as well as ventricular dilatation. ◆ PHT can be present mainly related to the presence of an unrestrictive VSD or more rarely related to the primum ASD.

Associated lesions Any associated congenital heart defect can be present and a full segmental analysis is essential. Commonly associated lesions are: ◆ Additional secundum ASD and additional muscular VSDs ◆ Associated PDA which can be difficult to detect in case of PHT ◆ Anterior deviation of the outlet septum can result in RV outflow tract obstruction (AVSD + tetralogy of Fallot) ◆ LVOT obstruction can be present and this can be associated with aortic coarctation or interrupted aortic arch ◆ AVSD can be associated with more complex situs anomalies (isomerism)

Post-​surgical imaging Surgical repair typically consists of closing the atrial and ventricular communications and involves variable interventions on the atrioventricular valve dependent on a variable degree of atrioventricular valve regurgitation. Typically, the ‘cleft’ in the left AV valve is closed surgically. Residual lesions include:

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts and the pressure and/​or volume loading caused by the PDA need to be assessed. The shunt size and direction can be assessed by 2D echocardiography, colour Doppler, pulsed Doppler, and continuous wave Doppler (E Fig. 53.7b). If the pulmonary vascular resistance (PVR) is normal, the flow is left to right (L→R) and continuous. Flow velocity is high in a restrictive PDA. The peak and mean gradient between the aorta and pulmonary artery can be measured. With increasing PVR, flow becomes bidirectional with R→L flow in systole and L→R shunting in diastole. With progressive pulmonary vascular disease, the shunt can be exclusively R→L. The L→R shunt will cause an increase in pulmonary blood flow and can result in LA and LV dilatation caused by LV volume loading. In case the duct is unrestrictive, PHT will be present causing pressure loading to the RV.

echocardiography can be helpful in determining the mechanisms contributing to residual AV-​valve regurgitation. ◆ LVOT obstruction can be present, often related to the development of subaortic obstruction. ◆ PHT can be present postoperatively.

Role of other imaging techniques Generally, echocardiography should be able to describe the anatomical and haemodynamic features of patients with AVSD pre and post-​operatively. In case of poor transthoracic windows, TOE can be helpful. In adults, aortic arch imaging and imaging of a PDA can be challenging and CMR or MSCT might be needed if clinically indicated. For patients with suspicion of elevated pulmonary vascular resistance, cardiac catheterization may be required to determine pulmonary vascular resistance.

Associated anomalies

Patent ductus arteriosus

In the adult population, an isolated PDA is the most common presentation, but associated congenital anomalies need always be excluded. As for any congenital defect, a full segmental analysis is required.

A PDA is not an uncommon lesion in adulthood. The L→R shunt causes left LV volume overload. If large, it may cause progressive obstructive PHT and Eisenmenger syndrome.

Imaging post surgery or intervention

Morphology of the PDA

A PDA can be closed surgically or interventionally by placement of a coil or a duct occluder [12]. After PDA closure, the following should be evaluated:

In a left aortic arch, the duct is usually located between the descending aorta and the left pulmonary artery. If the arch is right sided, the duct can be present between the descending aorta and the right pulmonary artery, but other locations like between the left subclavian artery and the left pulmonary artery are possible. This variability in location of the duct makes the echocardiographic diagnosis sometimes difficult. Colour flow Doppler can be helpful in identifying the duct location (E Fig. 53.7a).

◆ Residual shunting through the duct ◆ Residual PHT ◆ Residual LV dilatation and mitral regurgitation ◆ Obstruction on the left pulmonary artery after coil/​ device placement

Haemodynamic consequences of a PDA

Role of other imaging techniques

For the haemodynamic assessment of a PDA, the size of the duct, the presence of restriction to pressure, the direction of shunting,

A PDA can usually be diagnosed using TTE. Rarely, CMR or MSCT might be required especially if the origin of the duct is

(a)

(b)

Fig. 53.7  (a) Patent ductus arteriosus. Colour flow Doppler demonstrating aortic-​to-​pulmonary flow in the short-​axis view. The red colour represents the

diastolic flow though the arterial duct. (b) Patent ductus arteriosus. There is continuous left-​to-​right shunting from the aorta to the pulmonary artery through the duct. The high velocity across the duct excludes the presence of significant pulmonary hypertension.

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unusual. In case of PHT, cardiac catheterization may be required to assess the PVR and its responsiveness to pulmonary vasodilators may be helpful in therapeutic decision-​making.

Coarctation of the aorta In classic coarctation there is a narrowing of the aorta located distal to the origin of the left subclavian artery in proximity to the level of insertion of the arterial duct [13]. The morphology of the narrowing is variable but typically is discrete with variable degrees of hypoplasia of the isthmus and the transverse aortic arch. The more extreme form is interruption of the aortic arch, which obviously is extremely rare to be diagnosed in adulthood. The diagnosis should be clinical with arterial hypertension associated with poor or absent femoral pulses and an arm-​leg blood pressure gradient. Typically, large collaterals develop providing blood supply to the lower part of the body.

Imaging the morphology of coarctation of the aorta In adults, imaging coarctation of the aorta using echocardiography can be challenging due to the limited echocardiographic penetration and often limited visualization of the descending aorta. The best screening method for diagnosing coarctation of the aorta is scanning the abdominal aorta in a subcostal long-​axis view (E Fig. 53.8). If there is a decreased systolic flow with diastolic run-​off, this is suggestive for the presence of a narrowing of the thoracic aorta. To further identify the location of the narrowing, the suprasternal view should be used but this gives very often only very limited windows in adult patients (E Fig. 53.9, z Video 53.8). Colour flow Doppler can be helpful. If the distal aorta cannot be viewed in the presence of an abnormal abdominal flow pattern and clinical suspicion, additional imaging by CMR and MSCT may be required.

Fig. 53.8  Coarctation of the aorta. Abdominal aortic flow in aortic

coarctation. Typically there is a continuous flow pattern in the abdominal aorta with diastolic forward flow (arrows) instead of the normal pulsatile pattern.

Fig. 53.9  Coarctation of the aorta. The coarctation with an obvious

posterior shelve is located just distal to the origin of the left subclavian artery. There is a localized narrowing in the juxtaductal region with a prominent posterior shelve. BA = brachiocephalic artery; LCA = left carotid artery; LSA = left subclavian artery; Asc Ao = ascending aorta; Desc Ao = descending aorta.

Haemodynamic significance To determine the haemodynamic significance of the coarctation, the blood pressure gradient between a limb proximal and distal to the narrowing has to be measured. Continuous wave Doppler can be used to interrogate the gradient across the narrowed segment. The coarctation is significant if high velocities and anterograde diastolic flow is seen (diastolic run-​off due to continued pressure gradient in diastole) (E Fig. 53.10). The CW Doppler gradient may be misleading due to different factors: (1) the presence of a PDA or the development of arterial collaterals may reduce the gradient across the coarctation; (2) the simplified Bernoulli equation is less accurate for long segment lesion or segments with multiple stenoses; (3) often multiple obstructive lesions in series are present (such as hypoplasia of the transverse arch) that lead

Fig. 53.10  Coarctation of the aorta. Continuous wave Doppler through

the coarctation region. The typical ‘saw-​tooth’ pattern is identified with the typical diastolic run-​off.

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts to an increased peak velocity proximal to the descending aortic narrowing. The expanded Bernoulli equation should be used if the proximal velocity exceeds 1m/​s: Peak gradient = 4v2max-​coarctation –​4v2max-​pre coarctation. The arterial hypertension associated with coarctation, can cause secondary left ventricular hypertrophy (LVH) with increased LV wall thickness and mass. Secondary LV systolic and diastolic dysfunction can be present.

Associated lesions Coarctation can be associated with multiple other cardiac defects. The most common ones include: ◆ bicuspid aortic valve with variable degree of aortic valve stenosis or regurgitation ◆ subaortic stenosis due to a small outflow tract or subaortic membrane can be present ◆ mitral valve anomalies such as a parachute-​type mitral valve with mitral valve stenosis ◆ supravalvar mitral stenosis related to the presence of a supramitral membrane ◆ VSDs

Imaging post surgery or intervention After surgery or interventional treatment (balloon dilatation and/​or stent implantation), follow-​up imaging should focus on diagnosing residual arch narrowing (aortic arch hypoplasia), residual narrowing at the coarctation site, detection of aneurysm formation, and studying the secondary effects on LV mass and systolic and diastolic function. Especially the detection of aneurysm formation can be challenging by echocardiography in adults and additional imaging using CMR or MSCT is required. In case of stent implantation, MSCT is the modality of choice. Early development of coronary artery disease and ischaemic heart disease is possible and might also require additional imaging.

Role for additional imaging techniques In adults with coarctation of the aorta, there is an important role for CMR and MSCT in the preoperative and postoperative

assessment due to the limited visualization of the area of the coarctation and aortic arch using echocardiography.

Right ventricular outflow tract obstruction (RVOTO) The two most common lesions causing RVOTO are pulmonary valve stenosis and subvalvar pulmonary stenosis caused by RV muscle bundles.

Morphology of RVOTO The most common form of RVOTO is caused by pulmonary valve (PV) stenosis. The valve can be tricuspid, bicuspid or unicuspid with variable degree of dysplasia of the leaflets (E Fig. 53.11, z Video 53.9). There can be tethering of the valve leaflets in the supravalvar area causing additional supravalve narrowing which can influence the success of balloon dilatation of the PV. Subvalvar stenosis is caused by hypertrophy of RV muscle bundles causing dynamic obstruction in the right ventricular outflow tract (RVOT). Muscle bundles dividing the RV into a proximal and distal chamber characterize double chamber RV. Double chamber RV is differentiated from infundibular narrowing in that the obstruction is located lower within the body of the RV. A concomitant perimembranous VSD may be identified (E Fig. 53.12, z Video 53.10).

Haemodynamic assessment RVOT obstruction can generally be well diagnosed using TTE. The valve morphology can be assessed and, before intervention, the annulus size can be measured. If the gradient is muscular, it often has a dynamic component, which is characterized by a high peak late in systole. Continuous wave Doppler can be used to grade the severity of the obstruction. RVOT obstruction is considered severe if the Doppler peak gradient measures > 64 mmHg. Different factors can influence the gradient however: an atrial L→R shunt can lead to increased velocities and gradient overestimation. Conversely, RV dysfunction, severe tricuspid regurgitation, atrial R→L shunting and high pulmonary artery pressures due to a large PDA all result in a lower Doppler velocity across the stenosis and can cause underestimation of the severity. There can be secondary RV hypertrophy (RVH) indirectly reflecting the degree of obstruction but RVH is very difficult to quantify echocardiographically.

Fig. 53.11  Critical valvar pulmonary stenosis. The

pulmonary valve is thickened (arrow left panel) and there is limited opening of the valve leaflets with minimal antegrade flow (arrow right panel).

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Fig. 53.12  Double chambered right ventricle. A

hypertrophied muscle band is noted with flow acceleration (arrows) in the RV cavity between the RV inflow and outflow. This patient also had a spontaneously closed perimembranous ventricular septal defect.

Associated lesions Multiple associated lesions can be present. The most common ones are: ◆ Atrial septal defects ◆ Ventricular septal defects

Imaging post surgery or intervention Generally, echocardiography can be used for post-​interventional follow-​up. After balloon dilatation or surgical valvotomy, residual PV stenosis can be present and Doppler can measure the gradient. Pulmonary regurgitation can be present and the severity can be evaluated by colour Doppler and continuous wave Doppler. If severe, this can result in progressive RV dilatation and dysfunction as after tetralogy of Fallot repair. After muscle bundle resection, residual muscular obstruction can be present.

Role of other imaging techniques In the majority of patients, the diagnosis of RVOT obstruction can be made using echocardiography. In case of very poor transthoracic images, TOE can be helpful defining the level of obstruction (valvar, subvalvar, supravalvar). CMR can be used in the postintervention assessment particularly in patients with severe pulmonary regurgitation (PR) causing RV dilatation. CMR allows quantification of the pulmonary regurgitant fraction and regurgitant volume as well as the RV volumes and ejection fraction.

imaging may demonstrate early systolic closure of the aortic valve or fluttering of the aortic valve leaflets. Continuous wave Doppler should be used to assess the peak and mean gradients across the lesion. Diagnosis can be made by TTE and only rarely additional imaging modalities are required. Defining the exact location of the narrowing, describing the mechanism and the relationship to the aortic valve is the information required for surgical treatment. 3DE can visualize the LVOT en-​face and it allows assessment of the morphology and severity of the obstruction, as well as relationships with the aortic valve and aortic valve anatomy. Supravalvar stenosis is a rarer form of LVOT obstruction. The stenosis is typically localized at the level of the sinotubular junction. It can be membranous, hourglass-​shaped, and be associated with hypoplasia of the ascending aorta and also the more distal aortic arch. The coronary arteries may be involved in the supravalvar narrowing which puts these patients at risk for ischaemia, especially when arterial pressure decreases (e.g. with general anaesthesia). In patients with elastin gene mutations, associated pulmonary branch stenosis is not uncommon. Supravalvar stenosis can be secondary to surgery such as after the arterial switch procedure or Ross operation.

Left ventricular outflow tract obstruction Congenital abnormalities of the LVOT can be present in the adult population. This includes congenital aortic stenosis, subvalvar aortic stenosis, and supravalvar stenosis. The evaluation of congenital valve abnormalities does not differ from acquired aortic valve disease and the reader is referred to the chapters on aortic valve disease in this book (Chapters 50, 51, and 52).

Morphology of subaortic and supravalvar stenosis Subaortic stenosis is a narrowing in the LVOT below the aortic valve (E Fig. 53.13). Three subtypes can be identified: a membranous form, a fibromuscular ridge, and a fibromuscular tunnel. Colour flow Doppler detects turbulence while pulse wave Doppler helps to localize the origin of acceleration. M-​mode and 2D

Fig. 53.13  Subaortic stenosis. There is a fibromuscular ridge (arrow) in the left ventricular outflow tract below the insertion of the aortic valve.

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts

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Haemodynamic assessment The haemodynamic assessment of LVOT obstruction includes measurement of the peak and mean gradients by Doppler techniques. The gradient is best measured from the apical outflow tract views. For subvalvar stenosis, a peak gradient >50 mmHg is considered haemodynamically significant. Subvalvar stenosis can cause damage to the aortic valve resulting in associated aortic regurgitation. For supravalvar stenosis, the gradient is best measured from suprasternal windows. The secondary effect on the LV needs to be assessed including the occurrence of LVH and LV systolic and diastolic dysfunction.

Associated lesions In adult congenital patients, subaortic stenosis is typically seen in patients after VSD closure, after repair of double outlet RV and in patients with AVSD. It can also be present as an isolated lesion. Supravalvar stenosis is typically present in patients with elastin gene mutations and patients with Williams’ syndrome. It is associated in these patients with supravalvar pulmonary stenosis and pulmonary artery branch stenosis, hypoplasia of the aortic arch, arterial hypertension, and coronary artery narrowing.

Postoperative evaluation After surgical intervention, residual outflow tract obstruction and aortic valve function need to be evaluated. Recurrence of subvalvar stenosis is common and requires serial follow-​ up. Aortic valve function needs to be monitored, especially for the presence of progressive aortic regurgitation.

Role of other imaging techniques Generally, subvalvar and supravalvular stenosis can be diagnosed using TTE. For subvalvar stenosis, TOE can be helpful in those cases where the LVOT cannot be visualized well and can help to determine the mechanism of the obstruction better. In patients with supravalvular stenosis in the context of elastin gene abnormalities, the coronary arteries can be involved in the disease process. As the origins of the coronary arteries can be extremely difficult to image using TTE, additional imaging techniques may be required. These include TOE, CMR, MSCT, or angiography. These imaging modalities also allow a better assessment of the entire aortic arch and the pulmonary artery branches.

Fig. 53.14  Ebstein’s anomaly. The apical four-​chamber view shows the apical

displacement of the tricuspid septal leaflet (arrows) and the normally inserted anterior leaflet. There is a large atrialized portion the of the RV.

regurgitation (E Fig. 53.15, z Video 53.12). The severity of Ebstein malformation is largely determined by the degree of apical displacement and the severity of the tricuspid valve regurgitation (TR). Significant atrialization of the RV cavity results in a reduction of stroke volume and together with the TR this reduces RV output.

Haemodynamic assessment In the haemodynamic assessment, the evaluation of TR and tricuspid valve stenosis is important. Colour Doppler echocardiography can be extremely helpful to determine the degree of tricuspid regurgitation. Tricuspid stenosis is uncommon and the evaluation requires alignment with the tricuspid inflow,

Ebstein’s anomaly Ebstein’s anomaly is a relatively rare congenital abnormality that sometimes can be diagnosed in adulthood.

Morphology Ebstein’s anomaly of the tricuspid valve is defined by apical displacement of the septal and postero-​inferior leaflets of the tricuspid valve [14] (E Fig. 53.14, z Video 53.11). Typically, the tricuspid valve orifice is rotated superiorly towards the RV outflow tract. The anterosuperior leaflet is large and redundant (sail-​like). The displacement can be very significant and results in significant atrialization of the basal part of the RV reducing the stroke volume. This is associated with variable degrees of tricuspid stenosis and

Fig. 53.15  Tricuspid regurgitation associated with Ebstein’s disease. This is viewed from a short-​axis view as typically in Ebstein’s malformation the tricuspid valve opens in the direction of the right ventricular outflow tract. The regurgitant jet generally is best viewed from this view. The arrow indicates the tricuspid regurgitant jet at valve level.

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which can be challenging. The severity of the stenosis can be underestimated by a gradient measurement due to the presence of a patent foramen ovale (PFO)/​ASD.

Associated lesions An ASD or PFO is often present and can result in R→L shunting causing desaturation and is associated with a risk for paradoxical emboli. There can be associated PV stenosis. Other common associated lesions include LV non-​compaction cardiomyopathy and VSDs.

Postoperative evaluation Surgery consists of either a valvuloplasty of the TV or a TV replacement in case the valve is not deemed repairable. The recently introduced cone technique provides an anatomical repair of the valve. Postoperative evaluation involves assessment of tricuspid valve function (degree of regurgitation or stenosis), assessment of RV size and function, and also LV functional assessment.

Role of other imaging techniques Generally, Ebstein malformation can be diagnosed well by TTE. In adults with poor echocardiographic windows, TOE can be a useful additional imaging technique for assessing tricuspid valve function and to identify the presence of a PFO/​ASD. CMR is useful to determine RV volumes and function and to quantify the severity of tricuspid regurgitation. For patients needing surgical repair or replacement of the tricuspid valve, tricuspid valve function can generally be followed using TTE and no additional imaging techniques are required.

mitral valve stenosis and regurgitation is discussed in Chapter 13 of this book. The same techniques apply to patients with congenital valve abnormalities but the mechanisms for valve dysfunction are different.

Morphology of congenital mitral valve abnormalities Different types of mitral valve anomalies can be distinguished: Parachute mitral valve. This defect is characterized by an abnormality of the subvalvar apparatus with the support provided to the anterior and posterior leaflets by a single papillary muscle (most commonly the posteromedial papillary muscle). Typically, this results in decreased mobility of the leaflets with the presence of mitral stenosis. It can be associated with other left ventricular abnormalities such as subaortic stenosis, aortic valve disease, and coarctation of the aorta. Double orifice mitral valve. This is a left AV valve with two orifices each having their own attachments. The first type is associated with an AVSD. The second type is a mitral valve with two orifices each having their own chordal attachments and papillary muscles. The orifices can be stenotic or regurgitant. A short-​ axis view generally is diagnostic although the orifices might be in different planes.

Congenital mitral valve anomalies

Isolated cleft in the mitral valve. In an AVSD, the zone of apposition between the superior and the mural leaflets is sometimes called a ‘cleft’. An isolated cleft in the anterior mitral leaflet not associated with an AVSD, is a rare lesion that can cause progressive mitral regurgitation (E Fig. 53.16). While in an AVSD the cleft is oriented towards the interventricular septum, in an isolated cleft, the cleft is oriented towards the LVOT.

In adults, acquired mitral valve disease is much more common than congenital abnormalities of the valve. The evaluation of

The morphology of the mitral valve anomaly can generally be well described using 2-​DE. However, 3DE with an en-​face view of the

Fig. 53.16  Isolated cleft in the anterior leaflet of the mitral valve. Short-​axis view at the level of the valve leaflets. Typically the cleft is anteriorly oriented.

AML = anterior mitral valve leaflet; PML = posterior mitral leaflet.

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts mitral valve from the ventricular perspective will allow a better definition of the valve anomaly and the subvalvar apparatus.

Haemodynamic assessment The different anatomic abnormalities can be associated with variable degrees of mitral valve stenosis and regurgitation. The evaluation is identical to acquired mitral valve disease but prior to valve surgery, the surgeon should be aware of the exact mechanism causing valve dysfunction.

Associated lesions Mitral valve anomalies can be isolated but can be associated with other types of LV congenital abnormalities. This includes LVOT obstruction, aortic valve disease, and coarctation of the aorta. Other congenital defects associated include double outlet RV (parachute mitral valve).

Postoperative assessment Postoperative evaluation includes mitral valve function and left ventricular function.

Role of other imaging techniques Generally, TTE provides sufficient imaging but in case of poor windows, TOE may be required. There is a limited role for other imaging techniques as CMR and MSCT do not image the leaflets well.

Tetralogy of Fallot and tetralogy of Fallot with pulmonary atresia Tetralogy of Fallot is the most common cyanotic lesion which is rare to diagnose in adulthood as most of the patients will have been diagnosed and treated during childhood. Most patients in the adult congenital clinic are postoperative patients.

Fig. 53.17  Tetralogy of Fallot. Subcostal view demonstrating the anterior

deviation of the outlet septum causing subvalvar obstruction. The arrow indicates the anterocephalad deviation of the outlet septum, causing right ventricular outflow tract obstruction. LV = left ventricle; RV = right ventricle; VSD = ventricular septal defect; RVOT = right ventricular outflow tract; MPA = main pulmonary artery.

◆ Define the mechanism + severity of RV outflow tract obstruction: infundibular, valvular and or supravalvular (E Fig. 53.19). ◆ Define whether the pulmonary arteries (PA) are present and confluent. Measure the size of the proximal and distal PAs and look for PA branch stenosis. Exclude the presence of aorta-​pulmonary collaterals. ◆ Identify coronary artery abnormalities especially any coronary artery crossing the RV outflow tract. This can be an abnormal left anterior descending (LAD) from the right coronary artery

Morphologic description Tetralogy of Fallot (TOF) is defined as the combination of a large outlet VSD with overriding of the aorta associated with various degrees of RV outflow tract obstruction and secondary RV hypertrophy. The key anatomical feature of TOF is anterocephalad deviation of the outlet septum causing various degrees of muscular/​infundibular RV outflow tract obstruction (E Fig. 53.17, z Video 53.13 a-​c). This is associated with variable degrees of PV obstruction and hypoplasia of pulmonary artery branches. TOF with pulmonary atresia can be considered as an extreme form where no connection is present between the RV and the pulmonary circulation. The pulmonary perfusion can be duct-​ dependent to central pulmonary arteries or be dependent on aorta-​pulmonary collaterals [15]. The preoperative assessment of an uncorrected patient with TOF includes the following: ◆ Define the size and localization of the VSD + degree of aortic override (E Fig. 53.18): perimembranous to outlet (92%), doubly committed (5%), inlet VSD or AVSD (2%). If aorta overrides the VSD by more than 50%, this is called a double outlet RV.

Fig. 53.18  Tetralogy of Fallot. Parasternal long-​axis view demonstrating the ventricular septal defect extending to the outlet part of the septum and the overriding of the aorta over the defect (in this case around 50% override).

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Fig. 53.19  Tetralogy of Fallot. Parasternal long-​axis view tilted towards the right ventricular outflow tract. There is flow acceleration from below the valve, at the valve level due to the small pulmonary valve that domes and also tethers at the supravalvular level.

(RCA), an accessory LAD from the RCA, or a prominent conal branch from RCA. Typically, the origins of the coronary arteries are clockwise rotated. Before any intervention on the right outflow tract, including stenting and PV implantation, the relationship of the coronaries to the outflow tract and proximal pulmonary artery branches needs to be determined. ◆ Determine aortic arch anomalies: TOF can be associated with a right aortic arch and other arch anomalies. The presence of aorta-​ pulmonary collaterals needs to be determined.

Preoperative haemodynamic assessment The preoperative haemodynamic assessment mainly includes the determination of the severity of the RVOT obstruction and identifying the different levels of obstruction (infundibular, valvar, supravalvar). Different Doppler techniques need to be combined. The direction of shunting across the VSD needs to be determined.

Associated anomalies TOF can be associated with other lesions and, as for any congenital defect, a full segmental evaluation is required. ◆ Associated abnormalities like ASDs, left superior vena cava draining to the coronary sinus, additional VSDs, abnormal pulmonary venous return ◆ AVSD can be associated if the VSD extends to the inlet part of the septum ◆ Aortic arch anomalies: right aortic arch, double aortic arch ◆ Aortic root dilatation and progressive aortic regurgitation

Postoperative imaging Surgical repair of TOF includes closure of the VSD and surgical relief of RV outflow tract obstruction using different techniques. If the PV annulus is too small, a transannular patch is required to relieve the RVOT obstruction, resulting in severe PR. This can cause progressive RV dilatation and dysfunction. Postoperative evaluation includes the assessment of: ◆ Residual RV outflow tract obstruction ◆ Pulmonary regurgitation ◆ Residual VSD ◆ RV size and function ◆ Pulmonary artery branch stenosis ◆ Aortic root dilatation and aortic regurgitation ◆ LV function The most common residual lesion is PR resulting in RV dilatation and dysfunction (E Fig. 53.20, z Video 53.14 a and b). Timely replacement of the PV can prevent irreversible damage to the RV but timing of the valve replacement is still controversial and seems largely dependent on RV volume. Different imaging techniques can be used for the assessment of RV function in these patients [16–​18].

Role of different imaging techniques For the preoperative assessment in children, generally, echocardiography can provide all the necessary information. Only in case of pulmonary atresia with complex pulmonary perfusion through

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts

Fig. 53.20  Tetralogy of Fallot. Postoperative image. Severe pulmonary regurgitation after tetralogy of Fallot repair. The left panel shows a diastolic frame with a wide regurgitant jet at valve level and backflow originating from distally into the pulmonary branches (red colour in the branches). The Doppler (arrow) shows the short deceleration time typical for severe pulmonary regurgitation with flow only in early and mid-​diastole.

major aorta-​pulmonary collaterals, additional imaging may be required to delineate the pulmonary blood supply. CMR and MSCT both provide excellent images of the pulmonary circulation but angiography remains the clinical gold standard in the preoperative assessment of this lesion, especially if pressure measurements are required. For the postoperative assessment, echocardiography remains the first-​line imaging technique. It allows assessment of the presence of a residual VSD, residual RV outflow tract obstruction, severity of PR, TR, aortic root dilatation, and aortic regurgitation. In adults, the pulmonary branches can be difficult to visualize especially more distally. In patients with significant PR, RV dimensions and RV functional parameters can be obtained for serial assessment. We propose to use tricuspid annular systolic plane annular excursion (TAPSE), fractional area change, and pulsed tissue Doppler. 3DE can be used to measure RV volumes and ejection fraction if the windows allow for a good volumetric data acquisition. Strain imaging is an emergent technique that can be used to assess RV longitudinal function but has not found its way yet into the routine clinical practice. Apart from assessing RV function, the assessment of LV function is very important for this patient population as progressive LV dysfunction carries a poor prognosis for this patient population. Especially in the postoperative evaluation, there is an important role for the use of CMR mainly for quantifying RV volumes and ejection fraction, pulmonary regurgitant fraction and volumes and for better delineating the pulmonary branch anatomy. Timing of PV replacement may be influenced by measurement of RV volumes with a cut-​off value between 170 and 190 ml/​m2. In patients with contraindications to CMR, MSCT can be an alternative for measurement of RV size and function.

Transposition of the great arteries Transposition of the great arteries (TGA) is generally diagnosed in the immediate postnatal period as it causes significant cyanosis. An increasing number of patients with TGA are diagnosed during foetal life. Due to the success of the atrial and arterial switch operations, there is a growing population of patients surviving into adulthood.

Morphology of TGA and associated anomalies In TGA, the aorta arises from the morphological RV and the pulmonary artery from the morphological LV resulting in ventriculoarterial discordance [19]. In this paragraph we will discuss ventriculoarterial discordance with atrioventricular concordance. Most commonly in this condition the aorta is positioned rightward and anterior relative to the position of the pulmonary artery. Commonly associated lesions are: ◆ VSD in up to 50% of all patients. The VSD is most commonly located in the perimembranous area but can be located anywhere in the septum. In case of inlet extension, straddling of the tricuspid vale may occur. ◆ LVOT obstruction: subpulmonary and pulmonary stenosis which can preclude an arterial switch procedure. ◆ Coarctation of the aorta can be associated. ◆ Variable coronary artery anatomy. This is important when performing an arterial switch operation, which involves coronary artery transfer. In TGA, usually the left coronary artery originates from the right facing sinus (sinus 1) and the RCA from the left sinus (sinus 2). The most common coronary variant is the circumflex originating from the RCA from sinus 2 (18%). A single coronary artery or an intramural course of a coronary artery can make an arterial switch procedure more challenging and is important to identify preoperatively. The preoperative anatomy can generally be accurately diagnosed by TTE. Additional imaging is nowadays rarely required. The treatment for TGA has undergone an historical evolution as the atrial switch procedure (Senning or Mustard operation) was performed until the mid-​80s-​early 90s to be replaced by the arterial switch operation afterwards [20]. For TGA with VSD and LVOT obstruction, the Rastelli operation is performed although this was recently replaced by the Nikaidoh procedure in selected cases.

Postoperative imaging The postoperative imaging differs according to which type of surgery the patient underwent. For all patients, TTE is the first-​lime imaging technique. For specific indications, other imaging techniques may be used.

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Evaluation after the atrial switch procedure (Senning or Mustard) The principle of both surgeries is the same: the systemic venous return is rerouted to the LV and the pulmonary circulation and the pulmonary venous return is redirected to the RV and aorta. This redirects the systemic venous blood to the pulmonary circulation and the pulmonary venous blood to the systemic circulation. In a Mustard operation an intra-​atrial tunnel is constructed using artificial patch material while in a Senning operation the intra-​atrial rerouting is performed using native atrial tissue. The diagnostic imaging performed for both procedures is similar and requires [21]:

◆ Identifying the venous pathways to rule out tunnel obstruction or baffle leaks (E Fig. 53.21). Pathway obstruction is the most common problem, especially after Mustard procedure. The superior vena cava and IVC pathways as well as the pulmonary venous pathways need to be imaged. This requires multiple imaging windows and views, which sometimes can be difficult to image in adults. 3DE can be helpful in visualizing the pathways and their spatial relationships. TOE and CMR are needed when TTE cannot define the pathways well. Contrast echocardiography with injection of agitated saline through a peripheral intravenous cannula can help to detect pathway obstruction and baffle leaks. ◆ Assessment of systemic RV function and tricuspid regurgitation. Progressive tricuspid regurgitation and systemic RV dysfunction are common problems after the atrial switch procedure (E Fig. 53.22). Quantification of systemic RV function by echocardiography remains challenging. For RV functional assessment, we suggest using a combination of different methods

for serial follow-​up including TAPSE, fractional area change and tissue Doppler echocardiography. Strain imaging is emerging but its clinical use for this indication still remains to be proven. Also, 3DE could be used but generally the image acquisition is challenging with limited image resolution. Progressive tricuspid regurgitation after the atrial switch is considered a sign of RV dysfunction and failure. For RV functional assessment, CMR remains the clinical reference technique. Evaluation after the arterial switch operation The adult population of patients who underwent the arterial switch operation is quickly growing as the atrial switch operation has become obsolete in paediatric cardiac surgery. After the arterial switch operation the following problems may occur:

◆ Progressive neo-​ aortic root dilatation associated with neo-​ aortic valve regurgitation. ◆ In an arterial switch operation, the pulmonary trunk is put in front of the ascending aorta with the right pulmonary artery to the right and the left pulmonary artery to the left of the ascending aorta. Pulmonary branch stenosis can be caused by stretching the proximal pulmonary artery branches. Imaging the RV outflow tract and PA is required and can be difficult in postoperative patients after arterial switch (E Fig. 53.23). Peak velocities ≤2 m/​s (predicted maximum instantaneous gradient ≤16 mmHg) across the distal main pulmonary artery and branch PA are within normal limits after arterial switch procedure. TOE generally does not help to visualize the anteriorly located PA and MSCT or CMR might be the only non-​invasive alternative. ◆ Coronary artery stenosis can develop after the coronary transfer and has been reported to cause coronary artery stenosis in 10–​15% of all patients. Coronary stenosis and especially kinking can result in myocardial ischaemia. Monitoring of global and regional myocardial performance is important. Exercise or dobutamine stress echocardiography can be used to identify perfusion problems. Direct visualization of the coronaries is possible using cardiac CMR and MSCT. Coronary angiography should be considered in patients in whom coronary stenosis or occlusion is highly suspected. ◆ Ventricular size and function: evaluation of LV size and function is required in every patient after the arterial switch procedure. In patients with PA branch stenosis, assessment of RV function is also important.

Evaluation after the Rastelli procedure In patients who underwent the Rastelli procedure, the VSD has been closed creating a tunnel between the LV and the aorta and the RV is connected with a conduit to the PA. Imaging the patients after the Rastelli procedure involves:

Fig. 53.21  Apical four-​chamber view of patient after the Senning operation. The pulmonary venous atrium (PVA) is directing the pulmonary venous blood to the right ventricle. The systemic venous blood is directed through the systemic venous atrium (SVA) to the left ventricle. The RV becomes the systemic ventricle after this operation.

◆ Evaluation of the RV-​ to-​ pulmonary artery conduit and branch PA by 2DE, colour and spectral Doppler using several approaches. ◆ Evaluation of the LV-​to-​aortic valve pathway for obstruction and aortic regurgitation. ◆ Evaluation of LV function as LV dysfunction is a potential late complication after the Rastelli operation. ◆ Exclusion of residual VSDs.

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts

Fig. 53.22  Severe tricuspid regurgitation

after the Senning operation. The RV is dilated and hypertrophied. Notice the broad jet of regurgitation at the tricuspid valve level (arrow).

Congenitally corrected transposition of the great arteries Congenitally corrected transposition of TGA (ccTGA), is defined as atrioventricular discordance associated with ventriculoarterial discordance. This results in ‘physiological correction’ as the oxygenated pulmonary venous blood enters the LA which connects through the tricuspid valve to the morphological RV into the aorta [21]. Systemic venous deoxygenated blood enters the RA, which connects, to the morphologic LV through the mitral valve into the pulmonary circulation. This can be associated with situs anomalies, VSDs, and tricuspid valve anomalies. In 20% of cases there is dextrocardia [22]. Any imaging technique should describe the full anatomy as well the functional impact (systemic RV function and tricuspid regurgitation). Generally, this can be done using TTE, but in adults TOE or CMR might be required.

condition, the ventricles and the interventricular septum are oriented in a more vertical plane than usual which requires vertical rotation of the probe in the parasternal views. In the short-​axis view of TGA, the aorta is positioned anterior to the left of the pulmonary artery.

Morphology of ccTGA TTE is the first-​line technique to diagnose ccTGA (E Figs. 53.24–​53.26, z Videos 53.15 and 53.16). In usual atrial situs arrangement, the tricuspid valve and the RV are located on the left and the mitral valve and LV are positioned on the right. This can be easily detected on the apical four-​chamber view due to the more apical insertion of the tricuspid valve relative to the mitral valve. As the tricuspid valve is often abnormal in this condition, with some Ebstein-​like features, the apical displacement of the TV is more obvious. The presence of the moderator band and the more heavily trabeculated RV on the left also provides an imaging sign for ccTGA. Typically for this

Fig. 53.23  The arterial switch operation. Position of the pulmonary

arteries after the arterial switch procedure. Due to the commonly used LeCompte manoeuvre, the pulmonary artery bifurcation is located anterior to the aorta. MPA = main pulmonary artery; LPA = left pulmonary artery; RPA = right pulmonary artery.

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Fig. 53.24  ccTGA. Apical four-​chamber view in a patient

with congenitally corrected transposition of the great arteries (atrioventricular and ventricular arterial discordance). The left atrium (LA) connects through the more apically displaced tricuspid valve to the morphologic right ventricle (RV), situated on the left. The right atrium (RA) connects through the mitral valve to the morphologic left ventricle (LV) situated on the right.

Fig. 53.25  ccTGA long-​axis view. Parasternal long-​axis view in a patient with congenitally corrected transposition of the great arteries. The left atrium (LA) connects to the anteriorly located right ventricle (RV), which connects to the anteriorly located aorta (Ao). The pulmonary artery i(PA) s positioned posteriorly to the aorta.

Fig. 53.26  ccTGA short-​axis view. High parasternal short-​axis view in

a patient with congenitally corrected transposition of the great arteries. The aorta (AO) is seen anterior and slightly leftward of the pulmonary artery, which is posterior and branches into the left (LPA) and right (RPA) pulmonary arteries.

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts Commonly associated anomalies ◆ VSD (~60–​70%). Commonly perimembranous but other locations are possible. ◆ LV outflow tract and pulmonary stenosis (~40–​70%). Commonly subvalvular (aneurysmal valve tissue, chords, discrete fibrous obstruction) and valvar. ◆ Tricuspid valve abnormalities (~83–​90%). Variable pathology (increased apical displacement of septal leaflet (Ebstein’s like), thickened/​malformed leaflets, straddling). Tricuspid regurgitation is common and can be progressive. ◆ Mitral valve abnormalities (~50%). Cleft mitral valve is possible and, if a VSD is present, straddling through the VSD. ◆ ASD (43%). ◆ Other associated lesions: aortic stenosis, aortic coarctation, left atrial isomerism, coronary artery variants, complete heart block.

Haemodynamic assessment In any patient with ccTGA, haemodynamic assessment is focused on the systemic RV function and the severity of TR. Progressive TR is common in this condition related to the frequent anatomical abnormalities of the TV. This is generally not well tolerated by the systemic RV and can result in progressive RV dilatation and dysfunction. Severe TR should be treated surgically before irreversible RV dysfunction develops although optimal timing is sometimes difficult to determine. LVOT obstruction (subpulmonary obstruction) can be present and requires assessment of the severity together with a description of the mechanism causing the obstruction.

Pre and postoperative assessment Most of the assessment can be performed by TTE or by TOE in case of poor imaging windows. Assessment of patients with ccTGA should focus on: ◆ TR for possible repair or replacement. ◆ Evaluation of RV function. ◆ Assess feasibility of biventricular repair (double switch-​type procedure) or need for pulmonary artery banding (LV retraining). ◆ After pulmonary artery banding, assess LV function, hypertrophy, and tricuspid regurgitation. ◆ After atrial switch and Rastelli procedures, assess leak or obstruction across tunnels and conduits. ◆ Assess for worsening ventricular function and atrioventricular valve regurgitation.

Role for other imaging techniques CMR can be used in case of poor echocardiographic windows and for quantification of RV volumes and ejection fraction. CMR is also used for evaluating the effect of pulmonary artery banding and LV retraining on LV hypertrophy and LV function. CMR allows quantification of systemic and pulmonary blood flows. There is a role for MSCT in these patients as complete heart block is very common, pacemakers are frequently needed and these may not be CMR compatible. In patients with pacemakers who develop

systolic dysfunction, the possibility of RV dyssynchrony as a contributing factor to the development of systolic dysfunction should be considered. Strain imaging to study timing of myocardial events can be helpful in understanding the mechanisms.

The functionally univentricular heart This is a wide anatomic spectrum of patients in which one of the chambers is too small to sustain either the pulmonary or systemic circulation [23, 24]. The dominant ventricle can be a RV or a LV. A second smaller ventricle is invariably present. Sometimes, two adequately sized ventricles are present, but anatomy prevents septation (such as straddling of the atrioventricular valves). The segmental approach needs to be used to describe the morphology. This can generally be done using TTE, although in adults poor echocardiographic windows may require additional imaging techniques. Most adult patients with univentricular hearts will have been palliated by the Fontan operation. The principle is that the dominant ventricular chamber is used for the systemic circulation while the systemic venous blood is directed to the PA, bypassing the heart [25]. Since its introduction, the Fontan operation has undergone many modifications. Currently, the total cavo-​pulmonary connection with the lateral tunnel or the extracardiac conduit is the most commonly used. A fenestration is often placed between the systemic venous pathway and the pulmonary venous atrium. The fenestration allows a R→L shunt that decompresses the systemic venous pathway and maintains adequate cardiac output. In case of favourable haemodynamics, the fenestration can be device-​ closed. As different types of Fontan connections exist, knowing the exact surgical technique used is important for any imaging technique. Before looking at the Fontan connection, it is important to know the underlying morphology of the heart. This includes a description of the atrial situs (solitus, inversus, isomerism), the AV-​connections (double inlet, single inlet with left/​right absent connection), common inlet (unbalanced AVSD) (see E Fig. 53.27–​53.30). It is important to determine ventricular morphology of the dominant ventricle (left/​right). A small superior and rightward subarterial outlet chamber is typically a morphologic RV. A small inferior-​ posterior rudimentary chamber is typically a morphologic LV. The outflow tract to the aorta should be visualized and should be unobstructive. AV-​ valve and ventricular function should be assessed (z Videos 53.17–​53.19). Imaging a patient after the Fontan operation should include: 1. Visualizing the Fontan connections. The patency of the connections and absence of obstruction and thrombi should be assessed. This involves: ● Evaluation of the superior cavopulmonary anastomosis (E Fig. 53.31) as well as the entire IVC to pulmonary artery connection. ● Flow measurements in the superior and IVC should be obtained and the effect of respiration on the flows should be

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Fig. 53.28  Tricuspid atresia. Apical four-​chamber view in patient with

absent right atrioventricular connection (tricuspid atresia). The absent right atrioventricular connection is seen echocardiographically as an echogenic border between the right atrium and small right ventricle (arrow). The atrial communication between the right (RA) and left atria (LA) is widely patent. The mitral valve and left ventricle (LV) dominate the image. The right ventricle (RV) is barely seen in this image.

Fig. 53.27  (a and b) Double inlet left ventricle. Apical view of double inlet

left ventricle. (a) In this systolic frame, two separate AV valves connect the left atrium (LA) and right atrium (RA) to a single ventricle of left ventricular morphology (LV). The Fontan (F) connection is seen posteriorly. (b) Diastolic frame from an apical four-​chamber view in a patient with double inlet left ventricle. The right atrium and left atrium (A) connect via separate atrioventricular valves (arrows) to the dominant left ventricle (V). The Fontan circuit (F) is seen behind the right atrial cavity.

Fig. 53.29  Tricuspid atresia. Four-​chamber view obtained at

studied. In general there is low-​velocity flow with increase in flow velocities with inspiration. ● Evaluation of the patency and size of the fenestration. The mean gradient across the fenestration provides an estimate of the transpulmonary pressure gradient.

transoesophageal echocardiography in patient with absent right atrioventricular connection (tricuspid atresia). The left atrium (LA) connects through the mitral valve to the left ventricle (LV). No atrioventricular valve is discernible on the right and the absent connection is seen echocardiographically as an echogenic border between the right atrium and small right ventricle (RV). The posterior aspect of ventricular septal defect (VSD) is seen and is non-​restrictive.

Th e role of echo ca rdi o g r a phy i n di fferen t c on g en i ta l de f e c ts 2. Visualizing the pulmonary veins. Pulmonary venous obstruction should be excluded. All four pulmonary veins should therefore be identified after the Fontan operation and pulmonary venous flow should be evaluated using colour and spectral pulsed Doppler techniques. If pulmonary vein problems are suspected, additional imaging techniques like MSCT, CMR, and cardiac catheterization are required. 3. AV-​valve function. Low atrial pressure is a condition for optimal Fontan function. AV-​valve stenosis and more commonly AV-​valve regurgitation should be evaluated. 4. Ventricular function assessment is an important part of postoperative Fontan evaluation but due to the lack of quantitative techniques it is largely a subjective qualitative approach. Also, the evaluation of diastolic function is extremely difficult due to abnormal AV-​valve anatomy and abnormal pulmonary venous flow.

Fig. 53.30  Unbalanced AVSD. Apical four-​chamber view in a patient

with unbalanced atrioventricular septal defect. The right atrium (RA) is considerably larger than the left atrium (LA). The large primum atrial septal defect is denoted with an asterisk. The common atrioventricular valve opens preferentially to the right ventricle (RV) which is dominant. The left ventricle (LV) is small. The ventricular septal defect is seen as the space between the interventricular septum (S) and the atrioventricular valve.

● In case of an intracardiac type of connection, baffle leaks should be excluded. ● Flow to both PA should be assessed using colour and spectral pulsed Doppler. Visualization of the entire conduit might be extremely difficult and TOE or CMR are excellent non-​invasive alternatives.

5. Detection of aortic-​to-​pulmonary collateral flow. An estimated 80% of patients undergoing Fontan-​type operations already have, or subsequently develop, systemic arterial-​to-​ pulmonary arterial collaterals as a consequence of preoperative, or continued, hypoxemia. Competitive flow from these aorto-​pulmonary vessels can increase right-​sided pressures, thereby reducing systemic venous flow to the PA. These collaterals can be detected by TTE using suprasternal aortic views but MSCT, CMR, and angiography are more sensitive techniques for detecting collateral flow.

Eisenmenger syndrome Eisenmenger syndrome is characterized by irreversible pulmonary vascular disease as a result of a systemic-​to-​pulmonary communication (e.g. ASD, non-​restrictive VSD, non-​restrictive PDA, AVSD, aortopulmonary window, surgical systemic-​ to-​ pulmonary shunt). An initial L→R shunt reverses direction following an increase in PVR and arterial pressures [26]. The

Fig. 53.31  Bidirectional cavopulmonary anastomosis (bidirectional Glenn shunt). Suprasternal view. The superior vena cava (SVC) is connected end-​to-​side to

the right pulmonary artery (RPA). The functionally proximal left pulmonary artery can be visualized. With colour Doppler the flow through the connection and the proximal pulmonary arteries can be imaged.

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The role of ech o cardio gra phy i n a du lt c on g en i ta l hea rt di sease ◆ LV function (prognostic factor). ◆ Worsening tricuspid regurgitation (increasing afterload, annular dilatation, and RV dysfunction) and RA enlargement. ◆ Underlying structural defect, coexisting structural abnormalities, surgical shunts. ◆ Obstruction or aneurysm in main pulmonary artery and proximal branches. ◆ Colour flow Doppler helps define the anatomical defect and direction of shunting. Increased R→L shunting during supine bicycle ergometry, although the shunt may be small and difficult to demonstrate due to a low gradient. Contrast echo can enhance visualization of the shunt.

Role of TOE

Fig. 53.32  Septal flattening in pulmonary hypertension. Parasternal

short-​axis view. The interventricular septum is flat in systole due to the elevated pulmonary pressures. Due to the flattening (arrows), the LV has the configuration of a capital ‘D’.

R→L shunt causes systemic desaturation that is progressive with the increase in PVR. Due to the presence of a shunt, the RV will never reach suprasystemic pressures and becomes less dysfunctional compared with patients with primary pulmonary hypertension. Follow-​up of these patients involves defining the underlying structural defect causing the increased pulmonary pressures, the direction of shunting across the defect, the presence of associated lesions and RV and LV function. As for the other congenital lesions, TTE is the first-​line diagnostic technique. Usually, TTE can identify: ◆ RV hypertrophy, flattening and bowing of the interventricular septum in systole (‘D’ sign, see E Fig. 53.32). Diastolic flattening occurs with disease progression. ◆ Pulmonary artery systolic and diastolic pressures (septal configuration, peak gradient from RV to RA) from tricuspid regurgitation jet using modified Bernoulli equation (RV systolic pressure mmHg = tricuspid regurgitation peak velocity2 (m/​ s) × 4 + estimated RA pressure). This pressure will be equal to pulmonary systolic pressure if no gradient exists across the RV outflow tract. ◆ Mean pulmonary artery pressure estimated from peak early diastolic PR velocity and the diastolic pulmonary artery pressure estimated from the end diastolic PR velocity. ◆ Qualitative and quantitative assessment of RV function. With disease progression, RV enlargement and dysfunction may occur.

◆ Can be performed relatively safely and is usually well tolerated (even when baseline oxygen saturation levels are 30–​40 mmHg, valve area