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(BQ) Part 1 the book Catheter ablation of cardiac arrhythmias presents the following contents: Biophysics of radiofrequency lesion formation, guiding lesion formation during radiofrequency energy catheter ablation, irrigated and cooled tip radiofrequency catheter ablation, catheter microwave, laser and ultrasound - biophysics and applications,...
Catheter Ablation of Cardiac Arrhythmias Catheter Ablation of Cardiac Arrhythmias SECOND EDITION Edited by Shoei K Stephen Huang, MD Professor of Medicine College of Medicine Texas A&M University Health Science Center; Section of Cardiac Electrophysiology and Pacing Scott & White Heart and Vascular Institute Scott & White Healthcare Temple, Texas Distinguished Chair, Professor of Medicine College of Medicine Tzu Chi University Hualien, Taiwan Mark A Wood, MD Professor of Medicine Assistant Director Cardiac Electrophysiology Laboratory Virginia Commonwealth University Medical Center Richmond, Virginia 1600 John F Kennedy Blvd Ste 1800 Philadelphia, PA 19103-2899 CATHETER ABLATION OF CARDIAC ARRHYTHMIAS ISBN: 978-1-4377-1368-8 Copyright © 2011, 2006 by Saunders, an imprint of Elsevier Inc All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher Details on how to seek permission, further information about the Publisher's permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein) Notices Knowledge and best practice in this field are constantly changing As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein Library of Congress Cataloging-in-Publication Data Catheter ablation of cardiac arrhythmias / edited by Shoei K Stephen Huang, Mark A Wood – 2nd ed p ; cm Includes bibliographical references and index ISBN 978-1-4377-1368-8 (hardcover) Catheter ablation Arrhythmia–Surgery. I. Huang, Shoei K. II. Wood, Mark A [DNLM: 1. Tachycardia–therapy. 2. Arrhythmias, Cardiac–therapy. 3. Catheter Ablation–methods WG 330] RD598.35.C39C36 2011 617.4'12–dc22 2010039806 Executive Publisher: Natasha Andjelkovic Senior Developmental Editor: Mary Beth Murphy Publishing Services Manager: Anne Altepeter Team Manager: Radhika Pallamparthy Senior Project Manager: Doug Turner Project Manager: Preethi Kerala Varma Designer: Steve Stave Printed in Canada Last digit is the print number: 9 8 7 6 5 4 3 2 Huang, 978-1-4377-1368-8 To all the physicians, electrophysiology fellows, and friends who are interested in cardiac electrophysiology and catheter ablation as a means to treat patients with cardiac arrhythmias To my dearest wife, Su-Mei Kuo, for her love, support, and encouragement; my grown-up children, Priscilla, Melvin, and Jessica, for their love and inspiration; my late parents, Yu-Shih (father) and Hsing-Tzu (mother) for spiritual support To Pablo Denes, MD, Robert G Hauser, MD, and Joseph S Alpert, MD, who, as my respected mentors, have taught and inspired me Shoei K Stephen Huang, MD To my wife, Helen E Wood, PhD, for all of her patience and love, and to our daughter, Lily Anne Fuyan Wood, who fills my life with joy Mark A Wood, MD ctr0185 Contributors Amin Al-Ahmad, MD Assistant Professor of Cardiovascular Medicine Associate Director Cardiac Arrhythmia Service; Director Cardiac Electrophysiology Laboratory Stanford University Medical Center Stanford, California Eric Buch, MD Assistant Professor of Medicine Clinical Cardiac Electrophysiology; Director Specialized Program for Atrial Fibrillation UCLA Cardiac Arrhythmia Center David Geffen School of Medicine at UCLA Los Angeles, California Robert H Anderson, MD, PhD, FRCPath, FESC Emeritus Professor of Paediatric Cardiac Morphology London Great Ormond Street Hospital University College London, United Kingdom José A Cabrera, MD, PhD Chief of Cardiology Department of Cardiology Hospital Quirón Pozuelo de Alarcón Madrid, Spain Rishi Arora, MD Assistant Professor of Medicine Feinberg School of Medicine Northwestern University Chicago, Illinois Hugh Calkins, MD Professor of Medicine Director of Electrophysiology Johns Hopkins Medical Institutions Johns Hopkins Hospital Baltimore, Maryland Nitish Badhwar, MD Assistant Professor of Medicine Division of Cardiology, Cardiac Electrophysiology University of California, San Francisco San Francisco, California Javier E Banchs, MD Assistant Professor of Medicine Penn State Hershey Heart & Vascular Institute Penn State College of Medicine Hershey, Pennsylvania Juan Benezet-Mazuecos, MD Arrhythmia Unit Department of Cardiology Fundación Jiménez Díaz-Capio Universidad Autónoma de Madrid Madrid, Spain Deepak Bhakta, MD Associate Professor of Clinical Medicine Krannert Institute of Cardiology School of Medicine Indiana University Indianapolis, Indiana vi David J Callans, AB, MD Professor of Medicine Department of Cardiology; Director Electrophysiology Laboratory Department of Cardiology Hospital of the University of Pennsylvania Philadelphia, Pennsylvania Shih-Lin Chang, MD Division of Cardiology Department of Medicine National Yang-Ming University School of Medicine Taipei Veterans General Hospital Taipei, Taiwan Henry Chen, MD Stanford Hospital and Clinics East Bay Cardiology Medical Group San Pablo, California Contributors vii Shih-Ann Chen, MD Professor of Medicine Division of Cardiology Department of Medicine National Yang-Ming University School of Medicine Taipei Veterans General Hospital Taipei, Taiwan Thomas Crawford, MD Lecturer Division of Cardiovascular Medicine University of Michigan Ann Arbor, Michigan Mithilesh K Das, MBBS Associate Professor of Clinical Medicine Krannert Institute of Cardiology School of Medicine Indiana University Indianapolis, Indiana Sanjay Dixit, MD Assistant Professor of Cardiovascular Division Hospital of the University of Pennsylvania Philadelphia, Pennsylvania Shephal K Doshi, MD Director Cardiac Electrophysiology Pacific Heart Institute St Johns Health Center Santa Monica, California Marc Dubuc, MD, FRCPC, FACC Staff Cardiologist and Clinical Electrophysiologist Montreal Heart Institute; Associate Professor of Medicine Faculty of Medicine University of Montreal Montreal, Quebec, Canada Srinivas Dukkipati, MD Assistant Professor of Medicine Mount Sinai School of Medicine New York, New York Sabine Ernst, MD, PhD Consultant Cardiologist Royal Brompton and Harefield NHS Foundation Trust; Honorary Senior Lecturer National Heart and Lung Institute Imperial College London, United Kingdom Jerónimo Farré, MD, PhD, FESC Professor of Cardiology and Chairman Department of Cardiology Fundación Jiménez Diaz-Capio Universidad Autónoma de Madrid Madrid, Spain Gregory K Feld, MD Professor of Medicine Department of Medicine; Director Electrophysiology Program San Diego Medical Center University of California, San Diego San Diego, California Westby G Fisher, MD, FACC Assistant Professor of Medicine Feinberg School of Medicine; Director Cardiac Electrophysiology Evanston Northwestern Healthcare Northwestern University Evanston, Illinois Andrei Forclaz, MD Physician Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Mario D Gonzalez, MD, PhD Professor of Medicine Penn State Heart & Vascular Institute Penn State University Hershey, Pennsylvania David E Haines, MD Professor Oakland University-Beaumont Hospital School of Medicine; Chairman Department of Cardiovascular Medicine; Director Heart Rhythm Center William Beaumont Hospital Royal Oak, Michigan Michel Hạssaguerre, MD Professor of Cardiology Hơpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Haris M Haqqani, PhD, MBBS(Hons) Senior Electrophysiology Fellow Section of Electrophysiology Division of Cardiology University of Pennsylvania Health System Philadelphia, Pennsylvania Satoshi Higa, MD, PhD Second Department of Internal Medicine Faculty of Medicine University of the Ryukyus Okinawa, Japan viii Contributors Mélèze Hocini, MD Physician Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Bobbi Hoppe, MD Cardiologist Cardiovascular Consultants, Ltd Minneapolis, Minnesota Henry H Hsia, MD Associate Professor of Medicine School of Medicine Stanford University Stanford, California Lynne Hung, MD Cardiac Electrophysiologist Mission Internal Medical Group Mission Viejo, California Amir Jadidi, MD Physician Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Pierre Jaïs, MD Physician Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Alan Kadish, MD Professor of Medicine Northwestern University Chicago, Illinois Jonathan M Kalman, MBBS, PhD Professor of Medicine Department of Cardiology University of Melbourne; Director of Cardiac Electrophysiology The Royal Melbourne Hospital Melbourne, Australia David Keane, MD, PhD Cardiac Electrophysiologist Cardiac Arrhythmia Service St James's Hospital Dublin, Ireland Paul Khairy, MD, PhD Research Director Boston Adult Congenital Heart (BACH) Service Harvard University Boston, Massachusetts; Associate Professor of Medicine University of Montreal; Director, Adult Congenital Heart Center Canada Research Chair, Electrophysiology and Adult Congenital Heart Disease Montreal Heart Institute Montreal, Quebec, Canada George J Klein, MD, FRCP(C) Professor of Medicine Division of Cardiology Department of Medicine University of Western Ontario and University Hospital London, Ontario, Canada Sebastien Knecht, MD Physician Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Andrew D Krahn, MD Professor Division of Cardiology Department of Medicine University of Western Ontario London, Ontario, Canada Ling-Ping Lai, MD Professor of Medicine College of Medicine National Taiwan University Taipei, Taiwan Byron K Lee, MD Assistant Professor of Medicine Division of Cardiology, Cardiac Electrophysiology University of California Medical Center University of California School of Medicine San Francisco, California Bruce B Lerman, MD H Altshul Professor of Medicine Division of Cardiology; Chief, Division of Cardiology Director of the Cardiac Electrophysiology Laboratory Cornell University Medical Center New York Presbyterian Hospital New York, New York David Lin, MD Assistant Professor of Medicine Department of Medicine Attending Physician; Medicine/Cardiac Electrophysiology Hospital of the University of Pennsylvania Philadelphia, Pennsylvania Kuo-Hung Lin, MD Instructor of Medicine College of Medicine China Medical University Taichung, Taiwan Yenn-Jiang Lin, MD Division of Cardiology Department of Medicine National Yang-Ming University School of Medicine Taipei Veterans General Hospital Taipei, Taiwan Contributors ix Nick Linton, MEng MRCP Physician Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Li-Wei Lo, MD Division of Cardiology Department of Medicine National Yang-Ming University School of Medicine Taipei Veterans General Hospital Taipei, Taiwan Francis E Marchlinski, MD Professor of Medicine School of Medicine University of Pennsylvania; Director of Electrophysiology Hospital of the University of Pennsylvania Philadelphia, Pennsylvania Steven M Markowitz, MD Associate Professor of Medicine Division of Cardiology New York Presbyterian Hospital Cornell University Medical Center New York, New York John M Miller, MD Professor of Medicine Indiana University School of Medicine Director, Clinical Cardiac Electrophysiology Clarian Health Partners Indianapolis, Indiana Shinsuke Miyazaki, MD Surgeon Hôpital Cardiologique du Haut-Lévêque Université Victor Segalen (Bordeaux II) Bordeaux, France Joseph B Morton, PhD, MBBS, FRACP Department of Cardiology The Royal Melbourne Hospital Melbourne, Australia Isabelle Nault, MD Cardiologist and Electrophysiologist Hôpital Cardiologique du Haut Lévèque Université Victor Segalen (Bordeaux II) Bordeaux, France Akihiko Nogami, MD, PhD Clinical Professor Department of Cardiology Tokyo Medical and Dental University Bunkyo, Tokyo; Chief of Cardiac Electrophysiology Laboratory Cardiology Division; Director of Coronary Care Unit Cardiology Division Yokohama Rosai Hospital Yokohama, Japan Jeffrey E Olgin, MD Professor in Residence Cardiac Electrophysiology Division of Cardiology Department of Medicine Chief Cardiac Electrophysiology University of California, San Francisco San Francisco, California Hakan Oral, MD Associate Professor Director, Cardiac Electrophysiology University of Michigan Ann Arbor, Michigan Basilios Petrellis, MB, BS, FRACP Consultant, Arrhythmia Service University of Toronto St Michael's Hospital Toronto, Ontario, Canada Vivek Y Reddy, MD Professor of Medicine Mount Sinai School of Medicine New York, New York Jaime Rivera, MD Cardiac Electrophysiologist Director of Cardiac Electrophysiology Instituto Nacional de Ciencias Medicas y Nutricion Hospital Médica Sur Mexico City, Mexico Alexander S Ro, MD Clinical Instructor, Electrophysiology Northwestern University; Director Cardiac Device Therapies Department of Electrophysiology Evanston Northwestern Healthcare Evanston, Illinois Raphael Rosso, MD Senior Electrophysiologist Department of Cardiology The Royal Melbourne Hospital Melbourne, Australia José M Rubio, MD, PhD Associate Professor of Cardiology Director of the Arrhythmia Unit Department of Cardiology Fundación Jiménez Díaz-Capio Universidad Autónoma de Madrid Madrid, Spain Damián Sánchez-Quintana, MD, PhD Chair Professor of Anatomy Department of Anatomy and Cell Biology Universidad de Extremadura Badajoz, Spain 17 n Substrate-Based Ablation for Atrial Fibrillation 301 accuracy (83% versus 64%) than rapid atrial pacing for predicting recurrent AF.86 Because AF is easily inducible by pacing after cardioversion of persistent AF, reinduction of AF is usually not attempted in patients with persistent AF In patients with persistent AF, termination of AF during ablation is, however, associated with higher probability of long-term maintenance of sinus rhythm.33,36,85 Troubleshooting the Difficult Case Problems with PV isolation are covered in Chapter 15 For any ablation strategy, difficulty in catheter navigation may be indicative of the inaccuracy of the electroanatomic map due to limited number of registered points or patient movement during the case Preprocedure image acquisition with computed tomography or cardiac magnetic resonance imaging may aid in identifying variations in the individual atrial and PV anatomy Phased-array intracardiac echocardiography has been used to provide accurate two-dimensional imaging and three-dimensional reconstruction of the left atrium and the PVs In addition to defining the PV anatomy, intracardiac echocardiography can confirm catheter position at the venous ostium Inability to create continuous transmural lesions is a common challenge during linear substrate modification Potential causes are poor catheter stability and insufficient power delivery Switching to a different catheter or a preformed sheath may be helpful Steerable sheaths may offer better catheter stability; however, caution should be exercised to avoid myocardial perforation When confronted with an incomplete linear ablation, the first step should be careful remapping of the line for conduction gaps For the mitral isthmus, gaps most frequently occur at the ostium of the left inferior PV and epicardially near the mitral annulus Epicardial gaps should be suspected when left atrial ablation results in endocardial conduction delay recorded on the ablation catheter but not on the adjacent bipoles on the coronary sinus catheter.41 Also, the finding of early or fractionated potentials from the coronary sinus catheter may indicate epicardial gaps For the roof line, the most frequent sites of gaps are near the superior PV.44 A more anteriorly positioned line can be considered if all initial attempts fail For patients undergoing a second procedure after posterior left atrial isolation, gaps are found at any point along the ablation lines but most frequently at the left atrial appendage ridge, at the roof line, and near the PVs.39 For electrogram-guided ablation, recognition of CFAE by visual inspection can be tedious and subjective The use of automated algorithms provides consistency and usually identifies fewer CFAE sites than by physician interpretation The optimal settings for these algorithms have not yet been established, however Extensive ablation may be required to eliminate CFAEs Antral PV isolation greatly reduces the CFAE burden and should be performed first in a stepwise approach to AF ablation Complete elimination of electrograms may not be necessary, but local organization and loss of fractionated components may be sufficient For autonomic ablation, patient discomfort may be an issue during high-frequency stimulation mapping unless the patient is deeply sedated Prior ablation may interrupt neural interconnections from peripheral sites needed to manifest AV block during stimulation A specific sequence of ablation has been described previously to minimize this effect A summary of problems encountered during substrate ablation and possible solutions is given in Table 17-6 TABLE 17-6 TROUBLESHOOTING THE DIFFICULT CASE Problem Causes Solutions Difficult catheter manipulation Atrial enlargement, difficult anatomy Change sheath angulation or use steerable sheath Unable to produce block across lines Gaps from noncontiguous lesions Nontransmural lesions Careful mapping of ablation line for gaps, especially near PV ostia and left atrial appendage ridge, create new line parallel to first attempt, epicardial ablation (in CS for mitral isthmus line) Create new line parallel to first Redirect line, monitor esophageal temperature, displace esophagus with TEE probe, displace heart with intrapericardial balloon or steerable sheath Linear Ablation Tissue edema from preceding ablation Esophagus near ablation lines Electrogram-Guided Ablation CFAE sites difficult to identify Poor tissue contact Variable electrogram characteristics Diffuse, extensive CFAE sites Change sheath Average analysis over 5- to 10-sec window, use automated algorithm Linear ablation and antral PV isolation Ablation of Cardiac Autonomics Unable to elicit vagal reflex with mapping Prior ablation interrupts neural interconnections Ganglia remote from endocardial sites Patient unresponsive to electrical stimulation Perform autonomic mapping before other ablation Map epicardial sites Perform empirical antral PV isolation CFAE, complex fractionated atrial electrogram; CS, coronary sinus; PV, pulmonary vein; TEE, transesophageal echocardiogram 302 IV n Catheter Ablation of Atrial Fibrillation References Haïssaguerre M, Jais P, Shah DC, et al Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins N Engl J Med 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anatomy and electrophysiologic findings J Cardiovasc Electrophysiol 2006;17:1062–1067 73 Valderrabano M, Liu X, Sasaridis C, et al Ethanol infusion in the vein of Marshall: adjunctive effects during ablation of atrial fibrillation Heart Rhythm 2009;6:1552–1558 74 Bagge L, Blomstrom P, Nilsson L, et al Epicardial off-pump pulmonary vein isolation and vagal denervation improve long-term outcome and quality of life in patients with atrial fibrillation J Thorac Cardiovasc Surg 2009;137:1265–1271 75 Rossi P, Bianchi S, Barretta A, et al Post-operative atrial fibrillation management by selective epicardial vagal fat pad stimulation J Interv Card Electrophysiol 2009;24:37–45 76 Sakamoto SI, Schuessler RB, Lee AM, et al Vagal denervation and reinnervation after ablation of ganglionated plexi J Thorac Cardiovasc Surg 2010;139:444–452 77 Nakagawa H, Scherlag BL, Wu R, et al Addition of selective ablation of autonomic ganglia to pulmonary vein antrum isolation for treatment of paroxysmal and persistent atrial fibrillation [abstract] Circulation 2004;110:III–543 78 Oh S, Zhang Y, Bibevski S, et al Vagal denervation and atrial fibrillation inducibility: epicardial fat pad ablation does not have long term effects Heart Rhythm 2006;3:701–708 79 Chugh A, Oral H, Lemola K, et al Prevalence, mechanisms, and clinical significance of macroreentrant atrial tachycardia during and following left atrial ablation for atrial fibrillation Heart Rhythm 2005;2:464–471 80 Jais P, Shah DC, Takahashi A, et al Long-term follow-up after right atrial radiofrequency catheter treatment of paroxysmal atrial fibrillation Pacing Clin Electrophysiol 1998;21:2533–2538 81 Natale A, Leonelli F, Beheiry S, et al Catheter ablation approach on the right side only for paroxysmal atrial fibrillation therapy: long-term results Pacing Clin Electrophysiol 2000;23:224–233 82 Chen SA, Tai CT, Yu WC, et al Right atrial focal atrial fibrillation: electrophysiologic characteristics and radiofrequency catheter ablation J Cardiovasc Electrophysiol 1999;10:328–335 83 Lin YJ, Tai CT, Liu TY, et al Electrophysiological mechanisms and catheter ablation of complex atrial arrhythmias from crista terminalis Pacing Clin Electrophysiol 2004;27:1231–1239 84 O'Neill MD, Jais P, Takahashi Y, et al The stepwise approach for chronic atrial fibrillation: evidence for a cumulative effect J Interv Card Electrophysiol 2006;16:153–167 85 Oral H, Chugh A, Good E, et al A randomized evaluation of right atrial ablation after left atrial ablation of complex fractionated atrial electrograms for chronic atrial fibrillation Circ Arrhythm Electrophysiol 2008;1:6–13 86 Crawford T, Chugh A, Good E, et al Clinical value of noninducibility by highdose isoproterenol versus rapid atrial pacing after catheter ablation of paroxysmal atrial fibrillation J Cardiovasc Electrophysiol 2010;21:13–20 18 Stepwise Approach for Ablation of Persistent Atrial Fibrillation Matthew Wright, Shinsuke Miyazaki, and Michel Haïssaguerre Key Points The stepwise approach to atrial fibrillation ablation is to sequentially target all foci potentially contributing to the initiation and maintenance of the arrhythmia The three major steps in this strategy are (1) pulmonary vein isolation, (2) electrogram-based ablation, and (3) linear ablation Special equipment needed includes apparatus for transseptal access and a circular mapping catheter Computerized mapping systems may be used for image-guided pulmonary vein isolation and computerized determination of atrial cycle lengths Termination of atrial fibrillation occurs in 82% to 87% of patients during ablation About 25% of terminations are directly to sinus rhythm; however, the remainder convert to one or more atrial tachycardias that also require ablation Up to 50% of patients require repeat procedures for recurrent atrial arrhythmias Atrial fibrillation (AF) is the most frequent sustained human arrhythmia The incidence and prevalence of AF in the general population are rising,1 and it is estimated that 15.9 million people will have AF by 2050 in the USA alone2 if the incidence continues to rise at it has in the past two decades The overall prevalence of AF in the Framingham Heart Study was 6%, and in people older than 40 years, there was a 16% lifetime chance of developing AF without a history or precedent of heart failure or myocardial infarction In those older than 75 years, the prevalence is estimated at 10%.3 AF is associated with an increased risk for all-cause mortality, heart failure, and stroke,1,4,5 and it is also responsible for about one third of all hospitalizations with cardiac rhythm disturbance.6 As a consequence, AF constitutes a major socioeconomic and health care problem 304 It has been calculated that for the aging United Kingdom population, more than 0.9% of the entire National Health Service budget is already spent on managing AF and its consequences, principally stroke,7 and in the United States, an estimated $6 to $7 billion is spent on AF management per year.8 Although no difference in mortality has been proved to result from using antiarrhythmic medication,9 a rhythm or a rate control strategy has to be considered in symptomatic patients.10 If a rhythm control strategy is preferred, the first step still consists of trying at least one antiarrhythmic drug.6 In patients with symptomatic persistent AF, maintenance of sinus rhythm at year varies between 41% and 62% for sotalol and amiodarone, respectively.11 In the combined results from EURIDIS and ADONIS, which enrolled a combination of patients with typical atrial flutter, paroxysmal and persistent AF, only 38% had remained in sinus rhythm at year with dronedarone.12 In comparison, catheter ablation for paroxysmal AF has a 1-year success rate of between 69% and 87%,13–18 and many groups report success rates of more than 70% for persistent AF,19–32 including in patients with long-standing persistent AF, off antiarrhythmic drugs From these data, it seems clear that catheter ablation is superior to antiarrhythmic drugs in restoring and maintaining sinus rhythm over the long term in patients with both paroxysmal and persistent AF However, it has to be emphasized that the end points were not all the same in the different studies In ablation studies, success is defined as the absence of arrhythmia recurrences (AF and atrial tachycardia [AT]), whereas in several pharmacologic studies, the presence of sinus rhythm at the final follow-up has been considered a success regardless of any intervening periods of AF For example, in AF-related congestive heart failure, 73% of patients in the antiarrhythmic group were in sinus rhythm at last follow-up, but 58% of patients in this same group had experienced at least episode of AF during the study period.33 Additionally, patients in ablation studies are for the most part attempting second-line therapy, as opposed to those in antiarrhythmic drug trials, a significant proportion of whom were enrolled after a first episode and may represent a lower risk and more easily treated population 18 n Stepwise Approach for Ablation of Persistent Atrial Fibrillation 305 Great efforts are being made to improve the success rates of catheter ablation for AF, which, correctly, are not deemed good enough when compared with ablation of other cardiac arrhythmias However, the success rates of antiarrhythmic drugs in preventing AF are poor when judged by similar standards The current HRS/EHRA/ECAS guidelines on catheter ablation of AF support catheter ablation for symptomatic patients in whom at least one antiarrhythmic drug has failed or has not been tolerated.34 Electrophysiologic Mechanisms of Atrial Fibrillation Based on Early Ablative Experiences In the 1990s, early attempts at curing AF with catheter ablation by a percutaneous approach were inspired by the surgical maze technique and its subsequent modifications.35,36 These early attempts were based on the multiple-wavelet hypothesis, proposed by Moe and colleagues,37 with contributory experimental work by Allessie and associates.38 The hypothesis was that by compartmentalizing the atria using linear lesions, the critical mass of atrial tissue required for reentrant wavelets would no longer exist, thus curing AF Schwartz and coworkers were the first to try to replicate biatrial surgical linear approaches, with a high procedural success rate; however, this was at the cost of unacceptable complications.39 Replication of the surgical procedure by making linear lesions within the right atrium (RA) was unsuccessful.40 In the late 1990s, the pivotal role of the pulmonary veins (PVs) in triggering paroxysmal AF was recognized.41 This led to attempts at treating focal sources that triggered AF rather than compartmentalizing the atria.42 By mapping the atria, it was observed that paroxysmal AF was triggered by ectopic beats originating from within the PVs, and that by electrically isolating the PVs, AF was eliminated.43 Other reports also demonstrated the importance of PVs for AF perpetuation through automatic or reentrant mechanisms.44,45 A venous wave hypothesis has therefore been proposed as the main electrophysiologic mechanisms of paroxysmal AF, implicating PVs as the exclusive sources of venous waves and drivers maintaining the atria in fibrillation.46 For both paroxysmal and persistent AF, isolated sources maintaining AF within the left atrium (LA) and coronary sinus have been observed.18,47–49 Ablation for Persistent Atrial Fibrillation Although pulmonary vein isolation (PVI) without additional ablation has been attempted for patients with persistent AF, the success rates with this approach are disappointing PV isolation without additional ablation has been reported successful in 20% to 61% of cases, and ablation at sites of complex fractionated atrial electrograms (CFAEs) alone has been reported successful in 9% to 85% of cases,21,28,29,50–59 although some investigators have reported success rates of up to 95% with PVI alone (Table 18-1).60,61 For most patients with persistent AF, however, PVI alone is insufficient.62 Strategies that have combined two techniques, such as PVI and CFAE ablation, or PVI and linear ablation, or PVI, CFAE ablation, and linear lesions, have achieved success rates between 42% and 95% without antiarrhythmic drugs, with most centers reporting success rates of more than 70% in the short to medium term.19–32 Importantly, two or more procedures are often necessary to treat persistent AF or secondary AT, and patients considering ablative treatment should be aware that about half require more than one procedure.19 Technique of Stepwise Ablation The stepwise approach to AF ablation has three primary stages (Fig 18-1) The first step is electrical isolation of the thoracic veins, that is, the PVs with or without the superior vena cava The second step is to induce local electrogram organization by electrogram-based atrial ablation, including the atrial bodies, coronary sinus, and appendages The third step is to create linear ablation lines primarily targeting the LA roof, mitral isthmus, and cavotricuspid isthmus Thus, during persistent AF, stepwise catheter ablation sequentially targets all structures potentially contributing to initiation and maintenance of AF: (1) PVs, (2) LA tissue and RA targets, and (3) LA roof and mitral isthmus (using linear ablation) Each region is ablated following a sequential approach until AF termination, and the impact of ablation is assessed by measurement of AF cycle length in both appendages Each step is accompanied by an increase in AF cycle length until conversion of AF directly to sinus rhythm or more often to multiple ATs that are then systematically ablated.19,30,31 A fourth step is ablation of these residual ATs This sequential approach has resulted in unprecedented success in maintaining sinus rhythm in the medium term with recovery of atrial mechanical function in patients with long-standing persistent AF.63 Termination of AF occurs in 82% to 87% of patients,19,64 with 95% of the patients in sinus rhythm at year and 90% after more than years19; however, a second procedure is needed in about 50% of patients, mainly for AT.19,64 Atrial Fibrillation Cycle Length: A Real-Time Guide to Ablation Both the impact of ablation at each region and the amount of work remaining can be followed by monitoring the AF cycle length The AF cycle length can be reliably monitored during the procedure by averaging 30 consecutive cycles at the LA and RA appendages, which display unambiguous high-voltage and reproducible electrograms (Fig. 18-2).65 This can be measured with computer software and is relatively stable, with less than milliseconds of variation between repeated measures in most patients Studies have shown that AF cycle length correlates with the local refractory period, that it shortens in parallel with the duration of AF, and that drugs may affect it.66 However, AF cycle length prolongation during ablation at remote sites is evidence that the AFCL is not just a representation of the local refractory period.67 A study using advanced computer simulation demonstrated that the AF cycle length, as measured in the LA appendage, represents the sum of all fibrillatory activities converging to this area.65 The higher the number Clinical Outcome of Patients Undergoing Persistent Atrial Fibrillation Ablation Depending on the Strategy Study No of Patients with Persistent Atrial Fibrillation Duration of FollowUp (mo) Pappone et al, 2000112 12 Oral et al, 200532 80 Willems et al, 2006 Beukema et al, 2005113 Technique PV Electrical Isolation LA Linear Lesions Electrical Block at the Linear Lesions 9±3 CPVA No No No No No 83 25 9±4 CPVA No Yes No Yes No 68 32 14-17 PVI + linear lesions Yes Yes Yes No No 69 53 15 ± CPVA + linear lesions No Yes No No No 77 44 Oral et al, 2006111 146 12 CPVA + linear lesions No Yes No No No 74 Bertaglia et al, 2006114 74 20 ± CPVA + linear lesions No Yes Yes No No 70 64 Calo et al, 200627 80 14 ± CPVA + linear lesions No Yes No No Yes 85 52 Nademanee et al, 200457 64 12 CFAE NA No NA Yes Yes 88 13 Oral et al, 200754 100 13 ± CFAE NA No NA Yes Yes 57 Estner et al, 2008115 23 13 ± 10 CFAE No No NA Yes No Estner et al, 2008 54 13 ± 10 PVI + CFAE Yes No NA Yes No 41 Haïssaguerre et al, 2005116 60 11 ± PVI + CFAE + linear lesions Yes Yes Yes Yes Yes 95 Estner et al, 2008117 35 19 ± 12 PVI + CFAE Yes No* NA Yes No 74 26 O'Neill et al, 2009 153 30 ± 11 PVI + CFAE + linear lesions Yes Yes Yes Yes Yes 89 21 Rostock et al, 200896 88 20 ± PVI + CFAE + linear lesions Yes YES Yes Yes Yes 81 28 59 19 CFAE Ablation RA Ablation Success in Persistent AF Patients (%) Percentage of Antiarrhythmic Drugs in Persistent AF Patients *Linear lesions were performed if a macro re-entrant atrial tachycardia was mapped AF: atrial fibrillation; CFAE, complex fractionated atrial electrogram; CPVA, circumferential pulmonary vein ablation; LA, left atrium; PV, pulmonary vein; PVI, pulmonary vein isolation; RA, right atrium 306 IV n Catheter Ablation of Atrial Fibrillation TABLE 18-1 18 n Stepwise Approach for Ablation of Persistent Atrial Fibrillation 307 of elements participating in the AF process, the shorter the AF cycle length and the more complex the ablation Of note, the surface AF cycle length is also a marker for resistance to antiarrhythmic drugs and DC cardioversion.68–70 After each step of ablation, a gradual prolongation of AF cycle length is observed.30 More than a 5-millisecond increase in mean AF cycle length is considered significant for any intervention Conversion to sinus rhythm or AT usually occurs when AF cycle length reaches 180 and 200 STEPWISE APPROACH TO ATRIAL FIBRILLATION ABLATION Step Thoracic vein isolation Targets Locations • Pulmonary veins • Pulmonary veins • Superior vena cava • Superior vena cava Step Electrogram based ablation Targets Locations • CFAE • Left atrium • Continuous activity • Base LAA • Electrical gradient • Inferior LA • Local CL < mean LA CL • LA septum • Coronary sinus • Right atrium • Anterior RA • RAA Coronary sinus Os Step Linear ablation Targets Locations • Macroreentry circuits • LA roof • Mitral isthmus • Cavotricuspid isthmus AF termination to sinus − done AF termination to AT − continue Mapping and ablation of ATs Targets Locations • Focal tachycardias • Focal • Macroreentry circuits • LAA • Pulmonary veins • LA septum • Macroreentry • Mitral isthmus • LA roof • Cavotricuspid isthmus FIGURE 18-1 Stepwise approach to atrial fibrillation ablation The first three steps terminate atrial fibrillation to sinus rhythm or more commonly an atrial tachycardia The final stage addresses these postconversion arrhythmias AT, atrial tachycardia; CFAE, complex fractionated atrial electrograms; CL, cycle length; LA, left atrium; LAA, left atrial appendage; RA, right atrium; RAA, right atrial appendage milliseconds in patients off drugs (Fig 18-3).30 If AF persists during ablation of the LA despite a prolonged LA appendage cycle length, a lesser prolongation of the RA appendage cycle length would suggest that the RA may contain independent elements that participate in the AF process.65 Step 1: Thoracic Vein Isolation PV isolation is described in detail in Chapter 15 PV isolation (antral, ostial, or circumferential) invariably results in a better clinical prognosis in patients with paroxysmal compared with persistent AF.30,71–74 Despite these poor results when used as a stand-alone strategy, PVI is performed as the initial ablation step in all patients with persistent AF because spared PVs can lead to arrhythmia recurrence due to triggering foci.75 A circumferential catheter is used to map and guide ablation of PVs, which can be isolated individually or as ipsilateral pairs depending on venous anatomy, catheter stability, and the operator's preference In all cases, ablation is performed at least 0.5 to cm away from the PV ostia to avoid the risk for PV stenosis when possible However, it is sometimes necessary to go more distally to achieve PVI; for example, at the anterior part of the left superior PV, catheter stability is sometimes extremely difficult, necessitating ablation at the ostium and even just inside the vein For all veins, isolation is assessed by either electrical elimination or dissociation of the PV potentials.76 The superior vena cava may be targeted in this step After thoracic vein isolation, the cycle length is simultaneously measured in the RA and LA appendages and followed to access the effects of subsequent ablation on the cycle lengths in both chambers Step 2: Electrogram-Based Ablation In the second step of the stepwise approach, targets for electrogram-based ablation are areas with continuous electrical activity, complex fractionated activity, local cycle lengths between 70 and 120 milliseconds, and temporal gradient between adjacent bipoles (Fig 18-4).77–88 The techniques for electrogram-based ablation of AF are described in detail in Chapter 17 All parts of the left atrium are mapped; however, the base of the appendage and inferior left atrium–coronary sinus interface are often important sites for cycle length slowing Other sites requiring particular attention may be the interatrial I II III V1 RFd RFp FIGURE 18-2 Atrial fibrillation (AF) cycle length The AF cycle length can be easily assessed from both the left and right atrial appendages, where an unambiguous signal is recorded Either using automated software (as shown here, Bard Electrophysiology, Haverhill, MA) or by averaging 10 or more cycles, left and right AF cycle length is worked out (146 msec in this case for the left atrial appendage) and gives an indication of the difficulty of ablation and likelihood of procedural termination d, distal; RF, radiofrequency; p, proximal 308 IV n Catheter Ablation of Atrial Fibrillation AT AFCL (ms) 200 180 160 CS Inferior LA Posterior LA LA septum LA roof Anterior LA PV Baseline 140 SR AFCL (ms) 200 180 160 140 Mitral isthmus PV Posterior LA LA roof LA septum LAA SVC CS Inferior LA Baseline 120 Cumulative incidence of AF termination 5% 25% 53% 87% DC 140 120 Mitral isthmus PV SVC CS Inferior LA Posterior LA LA roof LA septum A Anterior LA Baseline 100 Number of patients AFCL (ms) 160 20 18 16 14 12 10 20 pts 17 pts 12 pts pts B Number of ablation steps for AF termination FIGURE 18-3 A, Evolution of the changes in atrial fibrillation cycle length (AFCL) in the left atrial appendage during each ablation step in three patients The first two patients (top and middle) converted to atrial tachycardia (AT) or sinus rhythm (SR) after a gradual or sudden increase in AFCL, whereas the third patient (bottom) had minimal increase in AFCL and required electrical cardioversion B, The figure demonstrates the number and cumulative percentage of patients terminating with each step of ablation Of note, the first three steps (PV isolation, atrial ablation, and CS/SVC ablation) were performed in a randomized order, whereas the final step was linear ablation in all cases AF, atrial fibrillation; CS, coronary sinus; LA, left atrium; PV, pulmonary vein; SVC, superior vena cava (From Haïssaguerre M, Sanders P, Hocini M, et al Catheter ablation of long-lasting persistent atrial fibrillation: critical structures for termination J Cardiovasc Electrophysiol 2005;16:1125-1137 With permission.) septum around the foramen ovale, the posterior atrium, and the anterior left atrium The perimeter around the foramen ovale for to cm is targeted by turning the ablation catheter posteriorly from the transseptal access site Ablation of the anterior septum near the His bundle is avoided The anterior left atrium is ablated along the collar of the appendage and extending superiorly to the roof A second, more medial line in this area can be performed Ablation of the LA endocardium adjacent to the coronary sinus typically slows and organizes electrical activity (Fig 18-5) Ablation of the inferior LA is accomplished by a linear ablation line along the coronary sinus between and o'clock in the left anterior oblique view (see Chapter 17) The medial starting position is along the interatrial septum By looping the catheter in the atrium with the tip directed toward the atrial septum, the line can be created by steadily withdrawing the catheter Additional ablation within the coronary sinus may also be needed with the goals of eliminating or slowing sharp potentials remaining in the coronary sinus electrical activity and to eliminate residual areas of rapid activation This is performed with an irrigated catheter within the coronary sinus beginning at the 4-o'clock position and withdrawing to the os A maximum of 25 W is used within the coronary sinus Ablation in the RA around the coronary sinus ostium is performed to dissociate the proximal coronary sinus musculature from the atria I II VI A1-2 LAA LAA A3-4 B5-6 B7-8 C9-10 C11-12 D13-14 D15-16 E17-18 E19-20 FIGURE 18-4 The figure demonstrates the slowing (from 145 to 170 msec, locally) and organization of local activity (right) with ablation at the anterior collar of the left atrial appendage (LAA) Note the activation gradient and activity spanning the entire cycle length observed on spines C and D of a multiple spline catheter (PentaRay, Biosense Webster, Diamond Bar, CA) at the site before ablation (left) (From Haïssaguerre M, Sanders P, Hocini M, et al Catheter ablation of long-lasting persistent atrial fibrillation: critical structures for termination J Cardiovasc Electrophysiol 2005;16:1125-1137 With permission.) I II III V1 RF D RF P CS D CS P I II III V1 04 05 06 07 08 09 10 CS D FIGURE 18-5 The ablation catheter (radiofrequency [RF], distal [D], and proximal [P]) placed in the distal coronary sinus (CS) records a typical example of continuous electrical activity The quadripolar reference catheter is proximal to the ablation catheter in the CS Ablation at that discrete site terminates the fibrillation, transforming it into an atrial tachycardia (arrow, lower panel) (From Jais P, O'Neill MD, Takahashi Y, et al Stepwise catheter ablation of chronic atrial fibrillation: importance of discrete anatomic sites for termination J Cardiovasc Electrophysiol 2006;17:S28-S36 With permission.) 310 IV n Catheter Ablation of Atrial Fibrillation Step 3: Linear Lesions The third step is the creation of linear lesions to form areas of conduction block (see Chapter 17) The first such linear lesion consists of the roof line, which connects the two superior PVs (Fig 18-6).16 The immediate end point is electrogram abolition along the line with verification of conduction block performed after the restoration of sinus rhythm The mitral isthmus line, which joins the mitral annulus to the PV either anteriorly or laterally,15,16,89 is reserved for patients whose AF is not terminated with prior ablation steps and those with perimitral macro-reentry after termination of AF The mitral isthmus line is technically difficult and usually requires ablation within the coronary sinus (see Chapter 17) Incomplete ablation lines may be proarrhythmic A recent study highlights that although PVI and electrogram-based ablation without linear lesions may be effective in terminating persistent AF in a significant number of patients, macro-reentrant AT requiring LA linear ablation is likely to occur during the overall follow-up period.64 In this study, 96% of patients ultimately required a roof line and 86% a mitral line after a mean follow-up of years, despite attempts to avoid LA linear lesions These data suggest that at least the roof line (which is easier and simpler to perform than the mitral isthmus line) could be used in the case of AF persistence after PVI and CFAE ablation This study also confirmed the high risk for AT recurrence in cases of incomplete conduction block at LA lines I Right Atrial Ablation There is accumulating evidence that in a subset of patients, possibly up to 20% of patients with long-lasting persistent AF, the RA plays an active role in the perpetuation of AF.90 Ablation within the RA may be incorporated into previous steps or, as outlined here for clarity, as a separate process Prolongation of the left atrial cycle length to more than 170 milliseconds with persistently shorter (