ISSN The Official Journal of Korean Heart Rhythm Society Vol.14 No.3 September 2013 부정맥 부정맥 Arrhythmia The Official Journal of Korean Heart

ISSN 2005-9728 The Official Journal of Korean Heart Rhythm Society Vol.14 No.3 September 2013 부정맥 부정맥 Arrhythmia The Official Journal of Korean Heart Rhythm Society 심실빈맥 (I) Main Topic Reviews Korean Heart Rhythm Society Room 805, Masters Tower #553, Dohwa-dong, Mapo-gu, Seoul 121-040, Korea Phone 82-2-3275-5411 Fax 82-2-3275-5412 E-mail khrs@k-hrs.org http://www.k-hrs.org 심실조기수축특발성심실빈맥허혈성심근증환자에서심실빈맥확장성심근증환자에서심실빈맥 Article Review 브루가다증후군에서 milrinone 그리고 cilostazol 이부정맥발생을억제하는세포기전 ECG & EP Cases Ventricular Tachycardia Originating from the Right Ventricular Outflow Tract Terminated by Steam Pop A case of left bundle branch block-shaped wide QRS complex tachycardia with diagnostic ambiguity on a surface electrocardiogram Vol.14 No.3 통권 46 호 September 2013

The Official Journal of Korean Heart Rhythm Society 편집위원회 편집위원장 차태준 / 고신의대 편집위원 ( 가나다순 ) 김남호 / 원광의대남기병 / 울산의대박희남 / 연세의대오세일 / 서울의대 온영근 / 성균관의대이영수 / 대구가톨릭의대정보영 / 연세의대황교승 / 아주의대 Copyright 2013 The Official Journal of Korean Heart Rhythm Society Editorial Board & MMK Co., Ltd. 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, electronic, mechanical, photocopying, recording or otherwise without permission in written form from the copyright holder. This publication is published by MMK Co., Ltd.

편집자문위원 ( 가나다순 ) 고재곤 / 울산의대 곽충환 / 경상의대 김대경 / 인제의대 김대혁 / 인하의대 김성순 / 연세의대 김영훈 / 고려의대 김유호 / 울산의대 김윤년 / 계명의대 김종윤 / 연세의대 김준 / 부산의대 김준수 / 성균관의대 김진배 / 경희의대 남궁준 / 인제의대 노태호 / 가톨릭의대 박경민 / 인제의대 박상원 / 고려의대 박형욱 / 전남의대 배은정 / 서울의대 성정훈 / 차의과학대 신동구 / 영남의대 오동진 / 한림의대 오용석 / 가톨릭의대 이경석 / 전북의대 이만영 / 가톨릭의대 이명용 / 단국의대 이문형 / 연세의대 임홍의 / 고려의대 장성원 / 가톨릭의대 정중화 / 조선의대 조용근 / 경북의대 조정관 / 전남의대 최기준 / 울산의대 최윤식 / 서울의대 최의근 / 서울의대 최인석 / 가천의대 최종일 / 고려의대 한상진 / 한림의대 허준 / 성균관의대 현명철 / 경북의대

The Official Journal of Korean Heart Rhythm Society 목적과개요 부정맥 은 부정맥과관련된새로운임상지식, 진료지침, 증례등을소개하여부정맥연구회회원및개원의의지속적인의학교육에이바지하고자발행되는학술지입니다. 부정맥 은부정맥의진단과치료, 임상연구와관련된원저, 종설, 논평, 증례보고등의원고를공모하며, 제출된원고는편집위원회의검토를거쳐게재됩니다. 발행사 발행일 엠엠케이커뮤니케이션즈 대표 : 이영화편집 : 양관재, 유경아, 남대영디자인 : 홍선경, 유은영서울시강남구논현로 523 노바빌딩 3 층 Tel 02-2007-5400 Fax 02-2179-8431 http://www.mmk.co.kr E-mail: inquiry@mmk.co.kr 2013 년 9 월 30 일 부정맥은대한심장학회부정맥연구회가주관하며엠엠케이커뮤니케이션즈에서발행하고있습니다. 본지와관련된문의사항이나건의사항이있으시면발행사인엠엠케이커뮤니케이션즈로연락하여주시기바랍니다.

The Official Journal of Korean Heart Rhythm Society Vol.14 No.3 통권 46 호 September 2013 Contents Cover: Electrocardiograms of various premature ventricular contraction patterns (page 9). 심실빈맥 (I) Main Topic Reviews 심실조기수축 박경민 6 특발성심실빈맥 성정훈 10 허혈성심근증환자에서심실빈맥 김진배 16 확장성심근증환자에서심실빈맥 김진석 22 Article Review 브루가다증후군에서 milrinone 그리고 cilostazol 이부정맥발생을억제하는세포기전 차태준 26 ECG & EP Cases Ventricular Tachycardia Originating from the Righ Ventricular Outflow Tract Terminated by Steam Pop 김기훈 28 A case of left bundle branch block-shaped wide QRS complex tachycardia with diagnostic ambiguity on a surface electrocardiogram 안민수 34 자율학습문제 40

Main Topic Reviews 심실조기수축 건국대학교의과대학내과학교실박경민 Kyoung-Min Park, MD, PhD Division of Cardiology, Department of Internal Medicine, Konkuk University Hospital, Konkuk University School of Medicine, Seoul, Korea Premature ventricular contraction Abstract Premature ventricular contraction (PVC), also known as premature ventricular complex, ventricular premature contraction/complex, ventricular premature beat, or ventricular extrasystole, is a relatively common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node, the normal heartbeat initiator. The electrical events of the heart detected by an electrocardiogram allow PVC to be easily distinguished from a normal heartbeat. This paper provides useful information about PVC to physicians for understanding and managing clinical PVC Key words: arrhythmia catheter ablation premature ventricular contraction 서론 심실조기수축 (premature ventricular contraction, PVC) 은심실에서기원하는조기심장박동이다. PVC 는 규칙적인심장박동전조기에발생하기때문에정상 맥박보다이르게발생하며, 이로인해증상이 나타나기도한다. PVC 가일어나는동안동방결절 (SA node) 로부터정상적으로전기적신호가도달되기전에 심실은정상보다이른신호를보낸다. 이러한조기 신호는심실근의전기적인과민성때문이라고알려져 있으며심근경색, 전해질의불균형, 산소부족또는 Received: May 17, 2013 Revision Received: September 2, 2013 Accepted: September 28, 2013 Correspondence: Kyoung-Min Park, MD, PhD, Department of Internal Medicine, Konkuk University Hospital, Konkuk University School of Medicine, Seoul 143-729, Republic of Korea E-mail: bkm1101@hanmail.net 약물에의해생길수있다. 심실조기수축후심장의전기적시스템은즉시 reset된다. 이 resetting은심장박동에서짧은휴지를일으키고, 몇몇환자들은 PVC 후에심장이짧은순간멈추는것을느낀다고보고한다. PVC 의발생 PVC는건강한성인에서흔하게발견되는부정맥이다. PVC가있지만증상이전혀없는경우도많다. PVC는고령환자, 고혈압환자, 심장질환환자에서더일반적이다. 또한심장질환이나고혈압이없는젊고건강한사람에서도발생한다. 그러나최근의여러보고에서는증상이없어도 PVC가하루동안 24% 이상발생할경우심근기능저하에이를수있다고 6 The Official Journal of Korean Heart Rhythm Society

지적하였다. 1,2 결국 PVC로발생한심장의움직임이나달라진혈액의흐름이심장근육에혈류역학적으로좋지않은영향을주는것만은확실하다고판단된다. PVC 의원인 PVC의발생에는다음과같은원인이있다. 심근경색 고혈압 심근증 ( 울혈성심부전을포함 ) 승모판일탈증후군과같은심장판막질환 저칼륨혈증과저마그네슘혈증으로이뇨제를복용하는환자에서발생할수있다. 저산소증예를들면저산소증을일으키는폐기종또는만성폐색성폐질환과같은폐질환이심실조기수축을함께동반한다. Digoxin, aminophylline, tricyclic antidepressants 등의약물과 ephedrine 제제, 충혈완화제등 지나친음주 과도한카페인섭취 Cocaine, amphetamines 같은자극성약물사용 심근염과심장타박상 PVC는심장질환이없는건강한사람에서도나타날수있다. PVC 의증상 심장이짧은순간멈추는것을느낀다고한다. 이는 PVC 후심장의전기적시스템이 reset될때심장박동에서짧은휴지기가있기때문이다. 실제 PVC 박동은느끼지못할지도모른다. 왜냐하면심실조기수축의경우심장박동전에혈액으로채워질시간이없기때문이다. 따라서 PVC 환자들은종종건너뛰거나빠진박동이있다고호소한다. Bigeminy, trigeminy, couplets 또는 triplets 와같은 frequent PVC 환자들은종종증상이없다고보고된다 (Figure 1). 그러나드문경우힘이없음, 어지럼증, 졸도증상이보고된다. 이는잦은 PVC에의해심장이다른기관으로혈액을펌프질하는능력이약화되기때문이다. 3회또는그이상연이은 PVC를경험하는환자들은심실빈맥 (ventricular tachycardia, VT) 으로분류한다. 심실빈맥의지속은심장의 output 감소, 저혈압그리고실신으로이어진다. 또한심실빈맥은심실세동 (ventricular fibrillation, VF) 으로발전될수있으며, 이는돌연사에이를수있는치명적인심장리듬이다. PVC 의위험성 고혈압이나심장질환이없는건강한사람에있어 PVC는건강위험인자가되지않는다. 그러나심장질환 ( 심근경색, 심부전, 심장판막질환 ) 환자들에있어서 PVC는심실빈맥발생위험증가와관련이있을수있다. 심실빈맥은빠른심실수축의지속이며, 생명을위협하는부정맥이다. 그이유는다음과같다. Main Topic Reviews 드물게 PVC가있는환자들은종종증상이없다고보고되며, PVC 발생시증상을느끼지못한다. 이런경우 PVC는주로일상적인신체검사또는수술전검사로심전도를했을때발견된다. PVC 환자들은이따금가슴과목에두근거림을호소하며, 이두근거림은강력한심장박동으로인한불편감으로나타난다. 왜냐하면 PVC 직후심장박동은보통정상보다더강해지기때문이다. 일부 PVC 환자들은 1) 경고없이갑자기발생한다. 2) 빈번히심실세동으로발전한다. 심실빈맥은심실이급격하게떨리는혼돈상태의리듬이며, 심실세동이있는심장은혈액을효율적으로뇌와몸의나머지부분에공급할수없다. 따라서심실세동을치료하지않는다면수십분이내에사망할수도있다. 약 250,000명의미국인들이매년이러한 Vol.14 No.3 7

Main Topic Reviews 이유로사망한다. 많은의사들은 PVC가심실빈맥이나심실세동을항상일으키는것은아니라고여긴다. 대신 PVC는심근경색으로부터진행되고있는심장손상과같은심각한상태, 저칼륨혈증, 저산소증및 digoxin, aminophylline 독성상태의간접적이지만중요한지표가될수있다. 많은 PVC가무해하고양성이라고말할수있으려면우선구조적인심장질환이 PVC 발생과연관이없음이확인되어야한다. 만약근본적인심장질환에대한이상소견이없다면 PVC의예후가좋다는것을확신할수있다. 그러나최근 PVC의빈도가많은경우 ( 24%/ 24hrs) 1,2 그리고 PVC의넓이가넓은경우 ( 156 msec) 3 에는심근기능을저하시키는위험인자및예측인자가될수있다고보고된바있다. PVC 의치료 금연 PVC를유발하는질환들은또한생명을위협할수있다. 이러한질환들이있는경우종종병원에서사용되는 telemetry로 PVC, 심실빈맥등을발견할수있다. 이러한질환과대처법을예로들면다음과같다. 저칼슘혈증과저마그네슘혈증 : 칼슘과마그네슘은정맥주사로투여할수있다. Digoxin, aminophylline의독성 : 약물을투여할수있다. 급성심근경색 : 약물, 관상동맥조영술, 관상동맥중재술 (percutaneous transluminal coronary angioplasty) 은막힌관상동맥을개방하여심근에혈액공급을회복시키기위하여응급으로사용할수있다. 저산소증 : 산소를코로공급하고, 근본적인폐질환을치료하기위해약물을투여할수있다. PVC 자체가양성부정맥이라하더라도치료를해야하는이유는다음과같다. 두근거리는증상완화 PVC를발생시키는질환들은잠재적으로생명을위협하기때문에해당질환치료 심실빈맥과돌연사의발생을예방심장질환이없는건강한사람에게있어증상이없는 PVC는적극적으로치료할필요가없다. 그러나두근거림의완화를위해다음의방법을고려하는것이좋다. 음주, 카페인섭취중단 Pseudoephedrine을포함하는약물처럼 adrenaline 을함유할가능성이있는비염완화제를과다사용하지않을것 ( 체중감소를위한보조제는 PVC 를악화시킬가능성이있다 ) 4 Amphetamines, cocaine 같은약물의남용을줄일것 항부정맥제 항부정맥제는심실빈맥, 심방세동, PVC를제어하는데사용된다. 예를들면베타차단제, procainamide, flecainide/propafenone, amiodarone 그리고몇몇다른약제들이있다. 그러나일부항부정맥제는실제로심장의이상리듬을일으킬수있다는단점이있다. 따라서항부정맥제는심실빈맥과심실세동의고위험환자에게만신중하게처방해야한다. 잦은 PVC와심실성부정맥을유발하는중요한심장질환을가진경우또는실신등중증의증상이있는환자들에게는전기생리학검사를권고한다. 전기생리학검사는생명을위협하는심실성부정맥이있는지알아보기위해하는검사이며, 그결과악성부정맥이유발될가능성이있다면항부정맥제또는이식형제세동기 (implantable cardioverter defibrillator, ICD) 로돌연사예방치료를한다. 8 The Official Journal of Korean Heart Rhythm Society

Ventricular bigeminy Main Topic Reviews Ventricular trigeminy Ventricular couplet Ventricular triplet Figure 1. Electrocardiograms of various premature ventricular contraction patterns. 전극도자절제술 일반적으로부정맥은약물치료를통하여억제할수있지만, 이는근본적인치료라기보다는임시로부정맥의활동을억제하는것이며약물을중단하면재발될가능성이있다. 또한약물부작용이나타나는경우는약물을지속적으로사용할수없으며, 활동적인젊은연령에서는약물을평생지속적으로복용하는것이번거롭고경제적으로도상당한부담이된다. 최근에는심실조기수축을포함한심실성부정맥의경우에도상심실성빈맥의시술처럼도관을이용한절제술 ( 고주파전극도자절제술, radiofrequency catheter ablation) 을할수있다. 이는심도자검사와같은방법으로심장내에여러개의전극도자를넣어심실조기수축발생위치를정확하게찾아내고, 전극도자를통해고주파전류 (radiofrequency energy) 를주어그자리에열을발생시켜심실조기수축의원인이되는병소를완전히제거함으로써완치하는방법이다. References 1. Bogun F, Crawford T, Reich S, Koelling TM, Armstrong W, Good E, Jongnarangsin K, Marine JE, Chugh A, Pelosi F, Oral H, Morady F. Radiofrequency ablation of frequent, idiopathic premature ventricular complexes: Comparison with a control group without intervention. Heart Rhythm. 2007;4:863 867. 2. Baman TS, Lange DC, Ilg KJ, Gupta SK, Liu TY, Alguire C, Armstrong W, Good E, Chugh A, Jongnarangsin K, Pelosi F Jr, Crawford T, Ebinger M, Oral H, Morady F, Bogun F. Relationship between burden of premature ventricular complexes and left ventricular function. Heart Rhythm. 2010;7:865-869. 3. Deyell MW, Park KM, Han Y, Frankel DS, Dixit S, Cooper JM, Hutchinson MD, Lin D, Garcia F, Bala R, Riley MP, Gerstenfeld E, Callans DJ, Marchlinski FE. Predictors of recovery of left ventricular dysfunction after ablation of frequent ventricular premature depolarizations. Heart Rhythm. 2012;9:1465-1472. 4. Upadhyay S, Afaq M, Upadhyay S, Zarich S, McPherson C. Weight loss supplement provoked idiopathic ventricular tachycardia. Indian Heart J. 2007;59(6):494-496. Vol.14 No.3 9

Main Topic Reviews 특발성심실빈맥 차의과학대학교내과학교실성정훈 Jung-Hoon Sung, MD, PhD Division of Cardiology, Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Gyeonggi-do, Korea Idiopathic ventricular tachycardia Abstract Ventricular arrhythmias (VAs) in structurally normal hearts can be broadly considered under non-lifethreatening monomorphic and life-threatening polymorphic rhythms. VAs are commonly seen in young patients and typically have a benign course. Monomorphic VAs are classified on the basis of the site of origin in the heart, and the most common areas are the ventricular outflow tracts and left ventricular fascicles. The morphology of the QRS complexes on an electrocardiogram is an excellent tool to identify the site of origin of the rhythm. Treatment options include reassurance, medical therapy, and catheter ablation. Very frequent ventricular ectopy may result in cardiomyopathy in a minority of patients. Key words: ablation electrocardiogram idiopathic ventricular tachycardia normal hearts 서론 유출로심실빈맥 특발성심실빈맥 (idiopathic ventricular tachycardia) 은심실빈맥 (ventricular tachycardia, VT) 이구조적으로정상이며반흔이없는심장에서발생하는것이다. 유출로심실빈맥 (outflow tract VT, OT-VT), 섬유속심실빈맥 (fascicular VT), 유두근심실빈맥 (papillary muscle VT), 윤상심실빈맥 (annular VT), 기타 (miscellaneous) 로분류할수있다. 1 1. 유출로심실빈맥 1) 메카니즘유출로심실빈맥은 catecholamine에의한 delayed afterdepolarization에의해이루어진다. 이메카니즘에의한 tachycardia는 adenosine, 베타차단제, 칼슘차단제로종료시킬수있다. 2 Received: June 21, 2013 Revision Received: September 2, 2013 Accepted: September 28, 2013 Correspondence: Jung-Hoon Sung, MD, PhD, Division of Cardiology, Department of Internal Medicine, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Korea Tel: 82-31-780-4864, Fax : 82-31-780-5584 E-mail: atropin5@cha.ac.kr 2) 유출로의해부학적특징우심실유출로 (right ventricular outflow tract, RVOT) 는좌심실유출로 (left ventricular outflow tract, LVOT) 에비해좌측및앞쪽방향으로위치한다. 그리고 pulmonic valve는 aortic valve의위쪽에위치한다. 10 The Official Journal of Korean Heart Rhythm Society

L A P R RAA LMCA RVOT RV Free wall RV Septum Main Topic Reviews A RA L N R P RCA LA Figure 1. Anatomy of the outflow tract. Anatomy of the typical right ventricular outflow tract (RVOT) of the heart. RVOT는 muscular infundibulum으로둘러싸여있고, LVOT는근육과섬유 (fibrous) 로이루어져있다. Aortic sinuses of Valsalva의오른쪽대부분과외쪽의일부분은 LVOT를덮고있고, AV node, His bundle에가까이있다. 1 임상적으로 septal RVOT와자유벽 (free wall) RVOT는전방, 중앙, 후방으로구분할수있다 (Figure 1). 2 전중격 (anteroseptal) RVOT는 LV epicardium 근처 interventricular vein 앞쪽에있다. Posteroseptal RVOT는 right coronary cusp 근처에있으며, RVOT- VT는주로 anteroseptal RVOT에서발생한다. 5 우심실유출로빈맥은좌각차단패턴 QRS에하향축을나타낸다. Precordial transition은주로 V4 또는그뒤에서이루어지고, V3보다일찍나타나지않으며, avl 과 avr은음성이다. Septal origin의심실빈맥은 QRS 기간이짧다. 6 폐동맥 (pulmonary artery, PA) 기원의 RVOT-VT에대한심전도기준은거의없다. 다만심전도상 PA origin 은하위유도 (inferior lead) 에서좀더 R 파가크고, avl/ avr에서 q파가큰비율을차지하여, V2에서 R/S 비율이크다. 2 2. 우심실유출로빈맥 3. LVOT/Aortic cusp tachycardia RVOT-VT는특발성심실빈맥 (idiopathic VT) 중가장흔하며심실빈맥의 70% 가량된다. 이것은좌각차단 (left bundle branch block, LBBB) 패턴의하향축 (inferior axis) 을가진다. 7 1) 심전도특징 1) 해부학 (anatomy) 후방 RVOT는 LVOT와대동맥근부 (aortic root) 의앞쪽에있다. 대동맥근부는심장의가운데에위치하고좌, 우, 비관상판첨으로되어있다. 비관상판첨 (noncoronary cusp) 은심실과바로연결이되지않아심실빈 Vol.14 No.3 11

Main Topic Reviews 맥의발생은거의없다. 좌우의판첨이심실과바로닿아있고좌심실근섬유 (muscle fiber) 는대동맥근부로뻗어있어심실조기수축 (premature ventricular contraction, PVC) 을만들수있다. 1 대동맥판첨에서발생하는빈맥은좌판첨이가장많고그다음이우판첨그리고좌우의판첨의접합부 (junction) 에서많이발생한다. 2) 심전도특징 LVOT 또는대동맥판첨에서발생하는심실빈맥은좌각차단패턴 QRS에하향축을갖지만, RVOT 위치보다 precordial transition이좀더빠르다. precordial의 R파는 V3 또는이보다먼저 transition된다. 좌판첨의 VT는 V1/V2에서 transition이있고우판첨은 V2/3에서나타난다. 대동맥판첨에서발생하는심실빈맥은 R 파가 0.5 ms로좀더넓고 V1, V2에서 R/S파가좀더크게나타난다. LVOT-VT는또한 aortic valve 아래쪽의 LV endocardium에서도나타날수있다. 빈도가낮은 LVOT-VT는 aortomitral continuity에서나타난다 (Table 1). 2 4. 심외막유출로심실빈맥심실빈맥은심외막 (epicardial) 에서거의발생하지않는다. MDI (maximum deflection index, 최초의 QRS 시작에서흉부유도에서최대편향까지의시간을총 QRS 기간으로나눈값 ) 로정량화해서 delayed initial precordial QRS activation이 0.55보다크면심외막심실빈맥을제안한다. 2 Lead I의하향축인 QS도심외막임을가리킨다. Transition 또는 pattern break라해서 V1 to V2의 R파가없어지는것 (QS 또는 rs) 이보이고 V3의 R파가잘보이는것은 aortic root의앞쪽의 anterior LV를가리킨다. 이것이 lead I의 QS와같이보이면심실간정맥 (interventricular vein) 근처의심외막 (epicardial origin) 을가리킨다. 5. 예후 Outflow tract의 VT는주로양성이며대부분은예후가좋다. 하지만두가지예외가있다. Short coupled PVC가 polymorphic VT를유발하거나죄심실기능장애 (LV dysfunction) 가빈맥에의해일어나는경우이다. 이런환자들은전기생리학검사가필요하다. 3 6. 검사및치료환자가전형적인 monomorphic outflow tract PVC를보이면홀터와심초음파로진단이충분하다. 만약 multiple PVC가있거나위치가특이하면 (free wall) MRI 같은검사를통해구조적인심장문제인 arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) 등이있는지고려해야한다. RVOT는 benign이나 ARVD/C가있는경우는돌연심장사 (sudden cardiac death) 의위험도및가족력을살펴봐야한다. 4,5 Table 1. Electrocardiographic classification of right ventricular outflow tract ventricular tachycardia (RVOT-VT) versus left ventricular outflow tract (LVOT)/aortic cusp ventricular tachycardia (VT) RVOT-VT LVOT/Aortic Cusp VT Later precordial transition (V3 or later) With V3 transition: VT transition later than sinus rhythm V2 transition ratio < 0.60 Narrower R-wave duration and greater R/S-wave amplitude ratio in V1 and V2 Earlier precordial transition (by V3) With V3 transition: VT transition earlier than sinus V2 transition ratio 0.60 Broader R-wave duration and greater R/S-wave amplitude ratio in V1 and V2 Notch (qrs) in V1 or V2 12 The Official Journal of Korean Heart Rhythm Society

1) 약물요법증상이있는 outflow tract VT에는베타차단제를일차적으로쓴다. 베타차단제를못쓰면 non-dihydropyridine 칼슘차단제 (verapamil 또는 diltiazem) 를쓸수있다. 2) 전극도자절제술전극도자절제술 (catheter ablation) 은비교적안전하고믿을만한치료방법이다. 심전도 localization이절제술을시행하는데도움이되나, 환자에게는위험도와치료효과를설명해야한다. 수면치료는심실빈맥을줄일수있어서삼가야한다. Isoproterenol을이용한 pacing 은심실빈맥을유발하는데도움이된다. 3D mapping 이절제술에도움이된다. Activation mapping은환자에서 PVC나 VT가잘나오면사용할수있고, bipolar electrogram의 earliest activation이 surface QRS보다 20-40 ms 앞설때성공적인절제부위로고려할수있다. Bipolar electrogram으로는일반적으로날카로운신속한초기편향을가지고있으며, sinus rhythm 동안후반편향의역전 (reversal of a late component present) 을보일수있다. Unipolar electrogram은주로 QS 패턴이뾰족하고아래로향하면서 surface QRS 앞에위치하면고려할수있다. 6 Pace mapping은 PVC/VT가잘나오지않을때시도할수있다. 빈맥의속도와비슷하게 mapping catheter 를 pacing한다. Pace mapping의 surface 12 심전도를임상의 VT/PVC와비교하는것이중요하다. 6 LVOT에서는 intracardiac echocardiography (ICE) 가도움이된다. 1 전극도자절제술의부작용은다른부위의절제술과비슷하다. 혈관으로접근하면서발생할수있는합병증, 심장천공 (cardiac perforation), 심낭압전 (cardiac tamponade), 뇌졸중, 심근경색등이있다. 섬유속심실빈맥 특발성좌심실빈맥 (idiopathic left VT) 또는섬유속심실빈맥은좌각 (left bundle branch) 의섬유속 (fascicles) 에서주로발생한다. 이것은심전도모양및해당되는섬유속 (corresponding fascicles) 에따라 left posterior fascicular VT, left anterior fascicular VT, left upper septal VT로나눈다. Left posterior fascicular VT가가장흔하고그다음이 left anterior, left upper septal 순이다. 1. 메카니즘 Verapamil sensitive left VT는 reentry에의한것으로이는심실또는심방자극에의해유도, 종결된다. 2. 심전도특징 Fascicular VT는우각차단 (right bundle branch block, RBBB) 패턴 QRS에 left superior axis를보인다. 이것은상대적으로좁아져 SVT가 BBB 패턴 QRS와같이있을때와혼돈될수있다. Left posterior fascicular VT는우각차단패턴 QRS에좌향편위 (left axis deviation, LAD) 가관찰되며, left anterior fascicular VT 의경우는우각차단패턴 QRS에우향편위 (right axis deviation, RAD) 가관찰된다. 중격 (septal) 심실빈맥은불완전한우각차단패턴 QRS에 normal axis를보인다. 3. 약물치료 Verapamil이빨리종결시키는데효과적이다. 만성적인 verapamil 치료는전극도자절제술을원하지않을때사용하며, 베타차단제또한효과적이다. 4. 전극도자절제술전극도자절제술은성공률이높아 90% 이상효과가있다. Fascicular potential이 PVC/VT with F-F (fascicular potential-fascicular potential) 보다앞서는것이중요하다. Earliest Purkinje potential이심실빈맥동안 QRS 앞에나오면성공적인절제부위로고려할수있다. Main Topic Reviews Vol.14 No.3 13

Main Topic Reviews 유두근심실빈맥 유두근심실빈맥은주로운동에의해서일어나고, catecholamine에민감해 isoproterenol 또는 epinephrine에의해유도된다. 발생기전은국소성이며회귀하지는않는다. 종종 multiple QRS를보이고자연히바뀌거나절제를통해바뀐다. 3 윤상심실빈맥 승모판과삼첨판륜 (tricuspid annulus) 에서도심실빈맥이발생한다. 각각의발생률은비슷하여삼첨판은 5-8%, 승모판은약 5% 이다. 승모판륜 (mitral annular) 심실빈맥 승모판륜심실빈맥은해부학적으로구분된다. 주로 Table 2. Specific locations and electrocardiographic features 2 Left cusp M or W pattern in V1 Monophasic R by V1/2 Tall R-wave amplitude in inferior leads Greater R-wave II/III ratio or III/II Lead I QS or rs Right cusp Monophasic R by V2/3 Larger R-wave amplitude in lead I R/L cusp junction Aortomitral continuity qrs in lead V1-V2 (notched downstroke), QS in lead V1 (notched downstroke) qr in lead V1 Rs/rs complex in lead I R-wave ratio < 1 in II/IIIqR in lead V1 Rs/rs complex in lead I R-wave ratio < 1 in II/III Epicardial MDI > 55% QS in lead I QS in II, III, avf (MCV) A Q-wave ratio in avl/avr >1.4 or an S-wave amplitude >1.2 mv A transition break, specifically a loss of R from leads V1 to V2 (QS or rs) with prominent R by V3 (AIV); MDI >55% QS in lead I QS in II, III, avf (MCV) A Q-wave ratio in avl/avr >1.4 or an S-wave amplitude >1.2 mv A transition or pattern break, specifically a loss of R from leads V1 to V2 S or rs) with prominent R by V3 (AIV) Pulmonary artery Tall R-wave in the inferior leads Larger Q-wave ratio in avl/avr Larger R/S amplitude in lead V2, larger R-wave amplitude in the inferior leads Larger Q-wave ratio in avl/avr Larger R/S amplitude in lead V2 Tricuspid annular Tricuspid inflow or para-hisian R- or r-wave lead I R or r with overall positive polarity in avl or r-wave I R or r with overall positive polarity in avl Large R-wave in I, R-wave or flat in avl, large R-wave in I, R-wave or flat in avl MDI (maximum deflection index): measured as the time from the earliest QRS onset to the maximum deflection in precordial leads, divided by the total QRS duration.qrs duration. 14 The Official Journal of Korean Heart Rhythm Society

anterior mitral annulus에서나오며 posterior or posteroseptal annulus는드물다. 심전도는우각전도차단패턴의 monophasic R 또는 Rs in lead V2-V6가보인다. 전극도자절제술은매우성공적이고이는 earliest ventricular activation 또는 12/12 pace map match를통해된다. 심실빈맥의기전을이해하고약물치료를하거나전극 도자절제술을시행하는것이도움이된다. References Main Topic Reviews 삼첨판륜심실빈맥 삼첨판륜심실빈맥은 8% 에서나타나며우측심실빈맥의 5% 에서보인다. Septal site는자유벽보다더많다고보고되었지만, 다른결과를보인연구도있다. 기타 1. 우심실에서발생하는부정맥 ARVD/C는다른심실빈맥과감별이중요하다. 2. Crux of the Heart 이곳은중간심장정맥 (middle cardiac vein) 과관상부비동 (coronary sinus) 의교차점에가깝게위치한심외막지점이다. 심전도는 left superior axis 및 early precordial transition과 delayed deflection을보인다 (Table 2). 2 결론 특발성심실빈맥은심실빈맥이구조적으로정상이며반흔이없는심장에서발생하는경우이다. 분류하면유출로심실빈맥, 다발성심실빈맥, 유두근심실빈맥, 윤상심실빈맥, 기타등으로구분된다. 이런심실빈맥은주로젊은환자에서비교적좋은예후를보인다. 12-lead 심전도로일반적인발생위치를확인할수있고, 특이한유형의경우결정적으로구별하는데에도도움이된다. 2 1. Prystowsky EN, Padanilam BJ, Joshi S, Fogel RI. Ventricular arrhythmias in the absence of structural heart disease. J Am Col Cardiol. 2012;59:1733 1744. 2. Hoffmayer KS, Gerstenfeld EP. Diagnosis and management of idiopathic ventricular tachycardia. Curr Probl Cardiol. 2013;38: 131-158. 3. European Heart Rhythm Association; Heart Rhythm Society, Zipes DP, Camm AJ, Borggrefe M, Buxton AE, Chaitman B, Fromer M, Gregoratos G, Klein G, Moss AJ, Myerburg RJ, Priori SG, Quinones MA, Roden DM, Silka MJ, Tracy C, Smith SC Jr, Jacobs AK, Adams CD, Antman EM, Anderson JL, Hunt SA, Halperin JL, Nishimura R, Ornato JP, Page RL, Riegel B, Priori SG, Blanc JJ, Budaj A, Camm AJ, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL; American College of Cardiology; American Heart Association Task Force; European Society of Cardiology Committee for Practice Guidelines. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guide lines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). J Am Coll Cardiol. 2006;48:e247-346. 4. Kiès P, Bootsma M, Bax JJ, Zeppenfeld K, van Erven L, Wijffels MC, van der Wall EE, Schalij MJ. Serial reevaluation for ARVD/C is indicated in patients presenting with left bundle branch block ven tricular tachycardia and minor ECG abnormalities. J Cardiovasc Electrophysiol. 2006;17:586-593. 5. Lee HW, Kim JB, Joung B, Lee MH, Kim SS. Successful catheter ablation of focal automatic left ventricular tachycardia presented with tachycardia-mediated cardiomyopathy. Yonsei Med J.2011; 52:1022-1024. 6. Takemoto M, Yoshimura H, Ohba Y, et al. Radiofrequency catheter ablation of premature ventricular complexes from right ventricular outflow tract improves left ventricular dilation and clinical status in patients without structural heart disease. J Am Coll Cardiol. 2005;45:1259-1265. 7. Hasdemir C, Ulucan C, Yavuzgil O, Yuksel A, Kartal Y, Simsek E, Musayev O, Kayikcioglu M, Payzin S, Kultursay H, Aydin M, Can LH. Tachycardia-induced cardiomyopathy in patients with idiopathic ventricular arrhythmias: the incidence, clinical and electrophysi ologic characteristics, and the predictors. J Cardiovasc Electro physiol. 2011;22:663-668. Vol.14 No.3 15

Main Topic Reviews 허혈성심근증환자에서심실빈맥 경희대학교의과대학내과학교실김진배 Jin-Bae Kim, MD, PhD Cardiology Division, Department of Internal Medicine, Kyung Hee University College of Medicine, #1, Hoegi-dong, Dongdaemun-gu, Seoul, Korea Ventricular tachycardia in ischemic cardiomyopathy Abstract Despite the decreased incidence of coronary artery disease, several studies showed that the ischemic ventricular tachycardia (VT) are most common type of ventricular tachycardia. Ischemic VTs have been known to arise in the ventricular scar or border zone, consisting of the reentry circuit. Therefore, reentry has been accepted as the principal mechanism of ischemic VT. However, recent studies showed a different background of the mechanism. In treatment, antiarrhythmic agents and implantable cardioverter defibrillator (ICD) are the first line of therapy. However, some cases require a more invasive approach, such as catheter ablation or cardiac surgery. The techniques of these treatments have evolved for several decades, showing better clinical outcome than before. Therefore, the management for ischemic VT should be tailored in patients with broadspectrum disease. Key words: cardiomyopathy ischemic ventricular tachycardia 서론 심장질환에서대표적인심근경색은심장에반흔 (scar) 을형성하여이와관련한심실부정맥을유발한다. 이러 Received: May 27, 2013 Accepted: September 28, 2013 Correspondence: Jin-Bae Kim, MD, PhD, Cardiology Division, Department of Internal Medicine, Kyung Hee University College of Medicine, #1, Hoegi-dong, Dongdaemun-gu, Seoul, Korea 130-702 Tel: 82-2-958-8200, Fax: 82-2-968-1848 E-mail: jinbbai@khu.ac.kr 한심근경색후발생하는심실빈맥 (post-infarct ventricular tachycardia) 은발생시기에따라급성기와만성기로나눠볼수있는데, 심근경색의급성기에는심실세동 (ventricular fibrillation) 으로이어지는다형성심실빈맥 (polymorphic ventricular tachycardia) 이흔하다. 경색후수주가지나면서경색부위에구조적인변화가발생하는데, 경색후발생되는섬유화는전도차단을일으키고경색주위의경계부위 (border zone) 에서는전도속도가느려지는현상이일어나면서이로인한회귀성경로가형성되는것으로알려져있다 1. 최근심근경색에대한치료가발전하면서이에따라심근경색이후발생하는심실빈맥의빈도가감소하게되었는데, 경색초 16 The Official Journal of Korean Heart Rhythm Society

기의연구에의하면약 5% 미만의심근경색생존자들에서심실빈맥이발생하는것으로나타났다 2. 일반적으로경색부위가넓고심기능저하가심한경우와경색후 6 주이내에심실빈맥의발생과급사의위험이높은것으로알려져있으며, 급성기이후에발생하는심실빈맥이전기적, 구조적재형성 (remodeling) 에의한것인지아니면또다른허혈손상 (ischemic insult) 에의한것인지는잘알려져있지않다. 다만이시기에발생하는심실빈맥은부정맥의기질 (substrate) 이형성되어있어회귀에의한기전으로발생하며, 약제로치료가어려운것으로알려져있다. 허혈성심실빈맥의기전 서론에서언급한대로허혈성심실빈맥 (ischemic ventricular tachycardia) 은심장의반흔과경색의경계부위의회귀기전에의해서발생하는것이가장중요한기전으로알려져왔다. 심근경색에따른반흔의형성에서정상심근과는달리정상적인혈액공급을받지못하는상태에놓인경계부위가혼재하면서, 서로다른성질의기질이함께존재해회귀기전은당연한것처럼평가되어왔다. 2010년 Indiana University 그룹의 Das 등은 9% 정도가국소성 (focal type) 이며대부분회귀기전으로발생한다고보고하였으나, 최근 2012년에발표된동물실험모델에기초한실험연구에의하면초기심실빈맥의유도및유지는 triggered activity에의한국소성기전에의해발생하다가오래지속되면서심실벽간회귀 (intramural reentry) 에의해다형성심실빈맥이나심실세동으로전환되는것으로밝혀졌다. 3,4 본실험은각심실박동을 3D mapping하여얻은자료를기초로한보고로초기심실빈맥의유발및유지는회귀가아닌국소성기전에의한것임을시사하며, 추후보다많은연구를통해인간에게도같은기전이존재하는지확인해야할것이다. 허혈성심실빈맥의치료 1. 항부정맥제와이식형제세동기회귀기전에결정적인역할을하는기질 (substrate) 에대한항부정맥효과와빈맥발생의방아쇠 (trigger) 를억제하는효과로인해항부정맥제가치료로흔히사용된다. 하지만약물치료 2년내 40% 이상의환자가재발을경험하게되고, 심실빈맥의재발은급사의위험도를증가시키게된다. 5 이런경우대안으로제시할수있는것이이식형제세동기 (implantable cardioverter defibrilator, ICD) 이다. 1997년과 2000년에발표된항부정맥제와 ICD의비교에대한연구들에서항부정맥제에비해 ICD가고위험군의생존기간을향상시킨것으로나타나이후 ICD가일차치료로인정받게되었고, 항부정맥제의부작용을줄이면서서맥에대한예방효과를보여주었다. 6-8 하지만 ICD가심실부정맥의발생을예방하지는못하고, 이미발생한부정맥에대한치료에있어국한된역할을함으로써항부정맥제의사용이필요하고, 환자에따라서잦은전기충격 (electrical shock) 으로인해삶의질문제를야기하기도한다. 또항부정맥제, 특히 amiodarone은심율동전환에너지의역치 (defibrillation threshold) 를증가시켜때로심율동전환을더어렵게하는것으로입증되었다. 따라서약물과의료기에의한치료가아닌전극도자절제술의필요성이부각되었다. 2. 전극도자절제술고주파절제술 (radiofrequency ablation) 은전술한것과같이자주재발되는심실빈맥에서부가적치료 (adjunctive therapy) 의의미가있으며, 항부정맥제를사용중임에도재발한허혈성심실빈맥의재발을 75% 이상감소시키는것으로알려졌다. 9-12 허혈성심실빈맥은혈역학적으로안정된상태인경우 (hemodynamically stable state) 와그렇지못한경우로나눠볼수있다. 전자의경우는빈맥의지도화 (mapping of ventricular tachycardia) 및전극도자절제술 (radiofrequency catheter ablation) 이심실빈맥을유도한상태에서진행하기때문에보다정밀한지도화와절제술로치료가용이한 Main Topic Reviews Vol.14 No.3 17

Main Topic Reviews Outer loop Bystander 1 Entrance site Common pathway (scar tissue) Exit site Inner loop Bystander 2 Bystander 3 Figure 1. Illustration of the circuit of ischemic ventricular tachycardia Table 1. The points of differential diagnosis of variable sites of the reentrant circuit. Site Electrogram timing in VT Entrainment with concealed fusion Entrained stimulus- QRS (S-QRS) VTCL Post-pacing interval Sinus rhythm pacemap QRS vs VT Stimulus- QRS Common pathway diastolic present =Egm-QRS <0.7 =TCL Same =Egm-QRS Inner loop systolic present <Egm-QRS >0.7 =TCL Same =Egm-QRS Outer loop systolic absent <Egm-QRS >0.7 =TCL Different <Egm-QRS Entrance site early diastolic present* =Egm-QRS <0.7 =TCL Different <Egm-QRS Exit site late diastolic present >Egm-QRS >0.7 >TCL Same =Egm-QRS Bystander 1 mid-diastolic* present >Egm-QRS >0.7 >TCL Same >Egm-QRS Bystander 2 late diastolic* present >Egm-QRS >0.7 >TCL Same >Egm-QRS Bystander 3 early diastolic* present* >Egm-QRS >0.7 >TCL Same >Egm-QRS *variable depends on whether captured orthodromically or antidromically 18 The Official Journal of Korean Heart Rhythm Society

V1 MAPp MAPd Main Topic Reviews V1 MAPp MAPd V1 MAPp MAPd V1 MAPp MAPd V1 MAPp MAPd V1 MAPp MAPd V1 MAPp MAPd Figure 2. Voltage mapping of substrate with 3D electroanatomic mapping system (CARTO ) not published data) 반면, 혈역학적으로불안정한경우는빈맥에대한자세한지도화가불가능하기때문에빈맥의발생과유지에결정적역할을하는심실의기질에대한지도화및이에대한절제술이진행된다. 회귀기전에대한이해와반흔사이의잠재적회귀로를확인하는방법등이발전함에따라여러다른회귀로에의한심실빈맥이나불 안정형심실빈맥에대한전극도자절제술에의한치료가확대되기에이르렀다 (Figure 1, table 1). 9,10 특히삼차원입체전기해부학적지도화 (3D electroanatomical mapping) 는전기생리학적자료를 3차원으로구현된해부학적자료와결부함으로써, 경색으로인한반흔의부위와정상부위, 경계부위를시술자에게직관적으로 Vol.14 No.3 19

Main Topic Reviews 제공하여시술이더욱용이하게되었다 (Figure 2). 최근 Michigan 그룹에서발표한 24명의심근경색환자를대상으로하는후향적연구에의하면반흔사이의채널이모두심실빈맥과관련되어있지않고, late potential 과함께존재하는채널이심실빈맥과연결된결정적경로 (critical pathway) 임을확인하였다. 13 이보고는기존의구조적질환과동반된심실빈맥의전극도자절제술의연구와일관된결과를보여주고있다. 예를들면부정맥유발형우심실이형성증 (arrhythmogenic right ventricular dysplasia) 이나브루가다증후군에서도비슷한결과를보여주고있다. 14-16 또하나심내막뿐아니라심외막에서도심실빈맥의유발이가능하기에동시에두부위에접근할필요가있는경우도고려해야한다. 최근증례보고에서심장이식수술을받은심실빈맥환자의전극도자절제술후심장병리소견을보면 lesion size를증폭시키는 irrigation tip catheter를사용했음에도 transmural lesion을얻지못하였음을알수있다. 이는심실빈맥치료시심내막으로의접근으로심외막에서유래하는심실빈맥이나심외막을결정적경로로이용하는심실빈맥을치료할수없음을반증하며, 반드시심외막에대한접근도고려해야함을시사한다. 17 또한 2013년 UCLA의 Tung 등이발표한자료를보면비허혈성심실빈맥환자에비해허혈성심실빈맥의경우심내막, 심외막양쪽으로모두전극도자절제술을시행한환자군에서심실빈맥의재발이의미있게적었음을알수있었다. 이는허혈성심실빈맥의전극도자절제술을시행하는경우반드시심내막과더불어심외막으로접근하는것도함께고려해야함을뒷받침한다. 18 3. 심실빈맥의수술치료심근경색후발생하는심근의재형성과심실류 (ventricular aneurysm) 와관련하여발생하는심실부정맥의치료목적으로수술적교정 (surgical correction or left ventricular aneurysmectomy) 이시도되었다. 1970~1980년대초기성적은항부정맥제치료성적에비해좋았으나수술후조기사망률이문제가되었고, 1990년대 Dor 등이수술법을변형한 subtotal endocardiectomy를 시행하여좋은결과를얻었으며, 이후 cryoablation이도입되면서수술후심기능향상및심실부정맥을줄이는결과를얻을수있었다. 19-22 하지만수술적응증에해당하지않는환자들에게는도움이되지않고, 수술경험이많은기관과적은기관의성적차이가커치료법이확대되지는못하였다. 현재에는관상동맥질환에심한심근재형성이동반되어수술치료를고려할때부가적인치료로받아들여지고있는실정이다. 결론 허혈성심실빈맥은관상동맥치료가발전함에따라그발생빈도가줄었지만, 아직도가장많은형태의심실빈맥이며예후가좋지않아적극적인치료가필요하다. 현재 ICD의보편화로허혈성심실빈맥으로인한사망률은줄었으나이로인해더많은부정맥이발견되고 ICD shock으로인해환자불편감이증가한경우전극도자절제술이부가적인의미로중요한치료법이될수있다. 현재시행되고있는전극도자절제술에대한이론적발전과기술의발전으로인하여시술에대한성적이향상되고있고, 아직도많은부분에서발전할여지가있기에보다더좋은결과가나올것으로예상된다. 또한카테터를이용한치료외에도국한된환자군에서는수술적치료도고려해야할것이다. References 1. Wit A, Janse MJ. The ventricular arrhythmia of ischemia and infarc tion: Electrophysiological mechanisms. Mount Kisco, NY: Futura; 1993. 2. Andresen D, Steinbeck G, Brüggemann T, Müller D, Haberl R, Behrens S, Hoffmann E, Wegscheider K, Dissmann R, Ehlers HC. Risk stratification following myocardial infarction in the thrombolytic era. J Am Coll Cardiol.1999;33:131 138. 3. Das MK, Scott LR, Miller JM. Focal mechanism of ventricular tachy cardia in coronary artery disease. Heart Rhythm. 2010;7:305 311. 4. Johnson CM, Pogwizd SM. Focal initiation of sustained and nonsustained ventricular tachycardia in a canine model of ischemic cardiomyopathy. J Cardiovasc Electrophysiol. 2012;23: 543 552. 20 The Official Journal of Korean Heart Rhythm Society

5. The ESVEM investigators. Determinants of predicted efficacy of antiarrhythmic drugs in the electrophysiologic study versus electrocar diographic monitoring trial. Circulation. 1993;87: 323 329. 6. The Antiarrhythmics versus Implantable Defibrillators (AVID) Investigators. A comparison of antiarrhythmic-drug therapy with implanable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias. N Engl J Med. 1997;337:1576 1583. 7. Connolly SJ, Gent M, Roberts RS, Dorian P, Roy D, Sheldon RS, Mitchell LB, Green MS, Klein GJ, O'Brien B. Canadian implantable defibrillator study (CIDS); a randomized trial of the implantable cardioverter defibrillator against amiodarone. Circulation. 2000; 101:1297 1302. 8. Kuck KH, Cappato R, Siebels J, Rüppel R. Randomized comparison of antiarrhythmic drug therapy with implantable defibrillators in patients resuscitated from cardiac arrest. The cardiac arrest study Hamburg (CASH). Circulation. 2000;102:748 754. 9. Marchlinski FE, Callans DJ, Gottlieb CD, Zado E. Linear ablation lesions for control of unmappable ventricular tachycardia in patients with ischemic and nonischemic cardiomyopathy. Circulation. 2000;101:1288 1296. 10. Soejima K, Suzuki M, Maisel WH, Brunckhorst CB, Delacretaz E, Blier L, Tung S, Khan H, Stevenson WG. Catheter ablation in patients with multiple and unstable ventricular tachycardias after myocardial infarction: short ablation lines guided by reentry circuit isthmuses and sinus rhythm mapping. Circulation. 2001;104: 664 669. 11. Stevenson WG, Friedman PL, Sweeney MO. Catheter ablation as an adjunct to ICD therapy. Circulation. 1997;96:1378 1380. 12. Strickberger SA, Man KC, Daoud EG, Goyal R, Brinkman K, Hasse C, Bogun F, Knight BP, Weiss R, Bahu M, Morady F. A prospective evaluation of catheter ablation of ventricular tachycardia as adjuvant therapy in patients with coronary artery disease and implantable cardioverter-defibrillator. Circulation.1997;96:1525 1531. 13. Mountantonakis SE, Park RE, Frankel DS, Hutchinson MD, Dixit S, Cooper J, Callans D, Marchlinski FE, Gerstenfeld EP. Relationship between voltage map "channels" and the location of critical isthmus sites in patients with post-infarction cardiomyopathy and ventricular tachycardia. J Am Coll Cardiol. 2013;61:2088-2095. 14. Jaïs P, Maury P, Khairy P, Sacher F, Nault I, Komatsu Y, Hocini M, Forclaz A, Jadidi AS, Weerasooryia R, Shah A, Derval N, Cochet H, Knecht S, Miyazaki S, Linton N, Rivard L, Wright M, Wilton SB, Scherr D, Pascale P, Roten L, Pederson M, Bordachar P, Laurent F, Kim SJ, Ritter P, Clementy J, Haïssaguerre M. Elimination of Local Abnormal Ventricular Activities : A New End Point for Substrate Modification in Patients With Scar-Related Ventricular Tachycardia. Circulation. 2012;125:2184-2196. 15. Marcus FI, Abidov A. Arrhythmogenic right ventricular cardiomyopathy 2012: diagnostic challenges and treatment. J Cardiovasc Electrophysiol. 2012;23:1149 1153. 16. Nademanee K, Veerakul G, Chandanamattha P, Chaothawee L, Ariyachaipanich A, Jirasirirojanakorn K, Likittanasombat K, Bhuripanyo K, Ngarmukos T. Prevention of ventricular fibrillation episodes in Brugada syndrome by catheter ablation over the anterior right ventricular outflow tract epicardium. Circulation. 2011;123:1270-1279. 17. Kelesidis I, Yang F, Maybaum S, Goldstein D, D'Alessandro DA, Ferrick K, Kim S, Palma E, Gross J, Fisher J, Krumerman A. Examination of explanted heart after radiofrequency ablation for intractable ventricular arrhythmia. Circ Arrhythm Electrophysiol.2012;5:e109 110. 18. Tung R, Michowitz Y, Yu R, Mathuria N, Vaseghi M, Buch E, Bradfield J, Fujimura O, Gima J, Discepolo W, Mandapati R, Shivkumar K. Epicardial ablation of ventricular tachycardia: an institutional experience of safety and efficacy. Heart Rhythm. 2013;10:490 498. 19. Guiraudon G, Fontaine G, Frank R, Escande G, Etievent P, Cabrol C. Encircling endocardial ventriculotomy: A new surgical treatment for life-threatening ventricular tachycardias resistant to medical treatment following myocardial infarction. Ann Thorac Surg. 1978; 26:438 444. 20. Josephson, M. E., Harken, A. H., Horowitz, L. N. Endocardial excision: A new surgical technique for the treatment of recurrent ventricular tachycardia. Circulation. 1979;60:1430 1439. 21. Cox JL, Gallagher JJ, Ungerleider RM. Encircling endocardial ventriculotomy for refractory ischemic ventricular tachycardia. Clinical indication, surgical technique, mechanism of action, and results. J Thorac Cardiovasc Surg. 1982; 83: 865 872. 22. Dor V, Sabatier M, Montiglio F, Rossi P, Toso A, Di Donato M. Results of nonguided subtotal endocardiectomy associated with left ventricular reconstruction in patients with ischemic ventricular arrhythmias. J Thorac Cardiovasc Surg. 1994;107:1301 1307. Main Topic Reviews Vol.14 No.3 21

Main Topic Reviews 확장성심근증환자에서심실빈맥 세종병원심장내과김진석 Jin-Seok Kim, MD. Department of Cardiology, Sejong Cardiovascular Center, Sejong General Hospital, Bucheon, Gyeonggi-do, Korea Ventricular tachycardia in patients with dilated cardiomyopathy Abstract Dilated cardiomyopathy (DCM) is the most common cardiomyopathy characterized by left or biventricular dilatation and systolic dysfunction. Ventricular tachycardia (VT) may be an important cause of sudden death and morbidity in patients with DCM. Although advances in both drug and device therapy have led to an improvement in overall survival of patients with DCM, symptomatic VT and the risk of sudden death are still issues that must be considered. Recent advances in catheter ablation technology have led to an improved success rate, and they have facilitated the use of catheter ablation in VT related to DCM. Key words: ablation dilated cardiomyopathy implantable cardioverter defibrillator ventricular tachycardia 서론 확장성심근증 (dilated cardiomyopathy, DCM) 은좌심실또는양심실의확장과심근수축기능저하를특징으로하는심근병증으로서울혈성심부전의중요한원인이되며, 질병의경과중심실성또는심방성부정맥이잘생기고급사의발생이증가하는것으로알려져있 다. 1, 2 특히심실빈맥은 DCM이동반된환자에서급사와연관되는주요한원인이다. 본논문에서는 DCM 환자에서의심실빈맥의임상양상, 발생관련인자, 발생기전, DCM의예후와관련된예측인자, 치료방법등에대해요약해서다루고자한다. DCM 환자에서의심실빈맥및급사 전체심부전환자의약 50% 는부정맥에의한급사 Received: May 30, 2013 Accepted: September 28, 2013 Correspondence: Jin-Seok Kim, MD, Department of Cardiology, Sejong Cardiovascular Center, Sejong General Hospital, Bucheon, Gyeonggi-do, Republic of Korea Tel: 82-32-340-1154, E-mail: heartmania@nate.com 이고나머지 50% 정도는심부전의악화로인해사망 하는것으로알려져있으며, 심부전증상이심해질수 록부정맥에의한급사보다는진행되는심부전으로사 22 The Official Journal of Korean Heart Rhythm Society

망한다. 2 그러나부정맥에의한급사또한 NYHA (New York Heart Association) class가높을수록증가하는것으로알려져있다. 3 심실빈맥은 DCM이동반된환자의 50~60% 에서관찰되며, 비지속형심실빈맥은 80% 까지관찰되지만, 심실빈맥이급사의유일한원인은아니다. 4 Luu 등에의하면말기심부전환자에서발생한심정지의 38% 만이일차적심실빈맥에의한것이었고, 나머지 62% 는서맥또는전기기계해리 (electromechanical dissociation) 등에의한것으로보고되었다. 5 심실빈맥발생관련인자및발생기전 DCM에서심실성부정맥의발현에는 DCM의병태생리와관련된다양한인자들이기여하는것으로보인다. 저칼륨혈증이나저마그네슘혈증등의전해질이상, 혈전또는색전에의한심근허혈등이부정맥발생에관여할수있다. DCM 환자의부검을통한연구중대상 DCM 환자의상당수에서좌심실심내막하반흔 (subendocardial scar) 및섬유화가진행된다수의부위가관찰되었는데, 이들병변은회귀성부정맥의기질로작용할수도있다. DCM에서진행되는심실의구조적및역학적변화는심실의다양한전기생리학적변화를초래하며, 비정상적자동능이나방아쇠활동등에의한부정맥이발생할수도있다. 체내 catecholamine의상승은직간접적으로부정맥의발생에기여할수있는것으로알려져있으며, DCM의치료에사용되는다양한약제역시부정맥을야기할수있다. 실제임상에서 DCM에서의심실빈맥발생기전에대해서는많은이견이있으나심근의반흔등에의한심근회귀빈맥 (myocardial reentry), 국소성심실빈맥 (focal origin), 각회귀심실빈맥 (bundle branch reentry) 등으로구분할수있다. Pogwizd 등은심장이식수술을받는 DCM 환자에서수술중시행한 mapping을통해심실빈맥이국소성기전에의해발생함을주장했으나, 6 DCM에서의심실빈맥은반흔과관련된심근내회귀기전에의한것이라고여겨진다. 7 Soejima 등은심실빈맥을보인 28명의 DCM 환자에대한전기해부학적 mapping 을통한연구에서 심실빈맥의 79% 는반흔과관련된심근회귀기전에의 한것이었고, 17% 는국소성이었으며, 7% 가각회귀에의 한것임을보고하였다. 8 각회귀심실빈맥은 DCM 에서매우특징적이며 His- Purkinje system 을포함하는대회귀 (macro-reentry) 기전에의한빈맥으로, 대체로전향전도 (antegrade conduction) 는우각으로, 역향전도 (retrograde conduction) 는좌각으로이루어진다. 이는전극도자절제술 로치료될수있는빈맥이므로 DCM 환자에서발생한 심실빈맥의 QRS 파의형태가동율동때의 QRS 파형태 와동일할경우, 반드시각회귀심실빈맥을의심해보 아야한다. DCM 환자의사망률의예측인자와심실빈맥 DCM 의예후는기저원인에따라차이가나는것으 로알려져있다. 9 특발성의경우 5 년사망률이약 20% 이 고, 이중급사는약 30% (8~51%) 에해당한다. 1, 2 DCM 의사망률을예측할수있는인자로는좌심실구혈률 이가장신뢰도가높으며, 그외에도폐모세혈관쐐기 압 (pulmonary capillary wedge pressure, PCWP 20 mmhg), 심박출계수 (cardiac index 2.5 L/min/m 2 ), 폐고혈압, 그리고중심정맥압상승등의혈역학적변수 들이있다. 10 또한 NYHA class III/IV, S3 sound 등도 DCM 환자의예후와관련이있으며, 실신 (syncope) 은 급사의고위험과연관되어있다. 저나트륨혈증이나혈중 norepinephrine, renin 등의 상승또한예후와관련이있다. 11, 12 DCM 환자에서의조 직생검소견이나좌심실의확장정도등은 DCM 환자의 생존과관련성은없는것으로알려져있다. 심전도에서 보이는좌각차단, 1 도또는 2 도방실차단, QRS 파간격 의연장등은 DCM의불량한예후와연관이있었다. 13, 14 비지속성심실빈맥 (non-sustained VT, NSVT) 의경 우 NYHA class I, II 의환자에서약 15~20%, NYHA class IV 에해당하는환자의 50~70% 에서발견되지만, 이 NSVT 와 DCM 에서의사망률이나급사와의연관성은 Main Topic Reviews Vol.14 No.3 23

Main Topic Reviews 명확하지않다. 또한 NSVT를가진환자들에서급사의고위험군을평가하기위한방법으로신호평균화심전도 (signal average electrocardiogram), 전기생리학검사등이이용되어왔으나, DCM 환자에서의그유용성은아직확실하지않다. 15 실의 dyssynchrony 를가진심부전환자를대상으로 한 CARE-HF (CArdiac REsynchronisation in Heart Failure) 와 COMPANION (Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure) 연구등에서사망률및유병률을낮추 는데효과가있음을보여주었다. 19, 20 약물치료및 device 치료 DCM 환자에서의안지오텐신전환효소억제제, 안지오텐신수용체차단제, 베타차단제등을이용한약물치료는좌심실기능저하를개선하여생존율을향상시키는것으로알려져있다. 하지만장기간의약물치료에도호전이없는경우이식형제세동기 (implantable cardioverter defibrillator, ICD) 나심장재동기화치료 (cardiac resynchronization therapy, CRT) 등이도움이될수있다. ICD는허혈성혹은비허혈성심근병증또는심실기능이낮고증상을동반하는지속성심실빈맥을가진환자의이차예방효과에서 amiodarone보다우월하다는것이입증되었다. 16 고위험군에서 ICD의일차적예방역할또한 DEFINITE (Defibrillator in Non-Ischemic Cardiomyopathy Treatment Evaluation) 연구와 SCD-HeFT (Sudden Cardiac Death Heart Failure Trial) 연구등을통해긍정적으로보고되었다. DEFI- NITE 연구에서 ICD는 DCM 환자에서부정맥에의한사망률을 80% 낮추고, 이러한사망률의감소는 NYHA class II 보다는 III의환자에서보다큰것으로보고되었다. 17 SCD-HeFT 연구에서는 NYHA class II 혹은 III의심부전을가지고좌심실구혈률이 35% 미만인관상동맥질환혹은비허혈성 DCM 환자에서표준약물치료와 amiodarone을사용한경우전체사망률개선효과는없었으나, ICD를시술한군에서는 5년후에 7.2% 의의미있는사망률감소를보였다. 18 DCM 환자의 30~50% 에서심전도상심실내전도장애및좌각차단이동반되는것으로알려져있다. CRT의경우 NYHA class III 또는 IV, 좌심실구혈률 35% 미만, QRS파의간격이 120 ms 이상이면서좌심 전극도자절제술 ICD가 DCM 환자의사망률은감소시키지만, 증상을동반하는심실빈맥의재발을예방하지는못한다. 또한고위험도환자에서일차적예방목적으로 ICD를삽입한환자중 2.5~12% 가부정맥을경험하는것으로알려져있다. 21 따라서전극도자절제술의역할이중요시되고있으며, 심실빈맥에대한전극도자절제술은 3차원영상의전기해부학적 mapping 시스템의도입등기술적발전과더불어서그치료성공률또한향상되고있다. 특히전극도자절제술은 DCM 환자에서자주관찰되는각회귀심실빈맥에효과적일수있다. 결론 DCM 환자에서심실빈맥의치료목적은첫째, 급사의위험을줄이는것이고, 둘째, 증상을동반하는심실빈맥발현을최소화하는것이다. DCM 환자는좌심실의기능저하가악화됨에따라급사및심부전과관련된사망이증가하는것으로보고되었다. 그러나베타차단제, 안지오텐신전환효소억제제및안지오텐신수용체차단제등의약물치료및의료기치료가발전됨에따라전반적인생존율이높아지고있다. 이와함께 DCM의유병률또한높아지고, 심실성부정맥의빈도가높아짐에따라이에대한적절한치료가요구된다. 최근전극도자절제술의발전으로 DCM에동반된심실빈맥에서이를이용한치료성공률이점차높아지고있다. 24 The Official Journal of Korean Heart Rhythm Society

References 1. Komajda M, Jais JP, Reeves F, Goldfarb B, Bouhour JB, Juillieres Y, Lanfranchi J, Peycelon P, Geslin P, Carrie D, Grosgogeat Y. Factors predicting mortality in idiopathic dilated cardiomyopathy. Eur Heart J. 1990;11:824-831. 2. Sugrue DD, Rodeheffer RJ, Codd MB, Ballard DJ, Fuster V, Gersh BJ. The clinical course of idiopathic dilated cardiomyopathy. A population-based study. Ann Intern Med. 1992;117:117-123. 3. Effect of metoprolol cr/xl in chronic heart failure: Metoprolol cr/ xl randomised intervention trial in congestive heart failure (merit-hf).lancet. 1999;353:2001-2007. 4. Larsen L, Markham J, Haffajee CI. Sudden death in idiopathic dilated cardiomyopathy: Role of ventricular arrhythmias. Pacing Clin Electrophysiol. 1993;16:1051-1059. 5. Luu M, Stevenson WG, Stevenson LW, Baron K, Walden J. Diverse mechanisms of unexpected cardiac arrest in advanced heart failure. Circulation. 1989;80:1675-1680. 6. Pogwizd SM, McKenzie JP, Cain ME. Mechanisms underlying spontaneous and induced ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy. Circulation. 1998;98: 2404-2414. 7. Hsia HH, Marchlinski FE. Characterization of the electroanatomic substrate for monomorphic ventricular tachycardia in patients with nonischemic cardiomyopathy. Pacing Clin Electrophysiol. 2002;25:1114-1127. 8. Soejima K, Stevenson WG, Sapp JL, Selwyn AP, Couper G, Epstein LM. Endocardial and epicardial radiofrequency ablation of ventricular tachycardia associated with dilated cardiomyopathy: The importance of low-voltage scars. J Am Coll Cardiol. 2004;43:1834-1842. 9. Felker GM, Thompson RE, Hare JM, Hruban RH, Clemetson DE, Howard DL, Baughman KL, Kasper EK. Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy. N Engl J Med. 2000;342:1077-1084. 10. Dec GW, Fuster V. Idiopathic dilated cardiomyopathy. N Engl J Med. 1994;331:1564-1575. 11. Keogh AM, Baron DW, Hickie JB. Prognostic guides in patients with idiopathic or ischemic dilated cardiomyopathy assessed for cardiac transplantation. Am J Cardiol. 1990;65:903-908. 12. Lee WH, Packer M. Prognostic importance of serum sodium concentration and its modification by converting-enzyme inhibition in patients with severe chronic heart failure. Circulation. 1986; 73:257-267. 13. Unverferth DV, Magorien RD, Moeschberger ML, Baker PB, Fetters JK, Leier CV. Factors influencing the one-year mortality of dilated cardiomyopathy. Am J Cardiol. 1984;54:147-152. 14. Schoeller R, Andresen D, Buttner P, Oezcelik K, Vey G, Schroder R. First- or second-degree atrioventricular block as a risk factor in idiopathic dilated cardiomyopathy. Am J Cardiol. 1993;71:720-726. 15. Grimm W, Christ M, Bach J, Muller HH, Maisch B. Noninvasive arrhythmia risk stratification in idiopathic dilated cardiomyopathy: Results of the marburg cardiomyopathy study. Circulation. 2003; 108:2883-2891. 16. A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias. The antiarrhythmics versus implantable defibrillators (avid) investigators. N Engl J Med. 1997;337:1576-1583. 17. Kadish A, Dyer A, Daubert JP, Quigg R, Estes NA, Anderson KP, Calkins H, Hoch D, Goldberger J, Shalaby A, Sanders WE, Schaechter A, Levine JH, Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation I. Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy. N Engl J Med. 2004;350:2151-2158. 18. Bardy GH, Lee KL, Mark DB, Poole JE, Packer DL, Boineau R, Domanski M, Troutman C, Anderson J, Johnson G, McNulty SE, Clapp-Channing N, Davidson-Ray LD, Fraulo ES, Fishbein DP, Luceri RM, Ip JH, Sudden Cardiac Death in Heart Failure Trial I. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med. 2005;352:225-237. 19. Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kap penberger L, Tavazzi L, Cardiac Resynchronization-Heart Failure Study I. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med. 2005;352:1539-1549. 20. Saxon LA, Bristow MR, Boehmer J, Krueger S, Kass DA, De Marco T, Carson P, DiCarlo L, Feldman AM, Galle E, Ecklund F. Predictors of sudden cardiac death and appropriate shock in the comparison of medical therapy, pacing, and defibrillation in heart failure (companion) trial. Circulation. 2006;114:2766-2772. 21. Moss AJ, Greenberg H, Case RB, Zareba W, Hall WJ, Brown MW, Daubert JP, McNitt S, Andrews ML, Elkin AD, Multicenter Automatic Defibrillator Implantation Trial IIRG. Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator. Circulation. 2004;110:3760-3765. Main Topic Reviews Vol.14 No.3 25

article REVIEW 브루가다증후군에서 milrinone 그리고 cilostazol 이부정맥발생을억제하는세포기전 고신대학교의과대학내과학교실차태준 Tae-Joon Cha, MD, PhD Division of Cardiology, Department of Internal Medicine, Kosin University College of Medicine, Busan, South Korea. Cellular mechanism underlying the effects of milrinone and cilostazol to suppress arrhythmogenesis associated with Brugada syndrome Szél T, Koncz I, Antzelevitch C. Heart Rhythm. 2013 Aug 1. pii: S1547-5271(13)00795-9. doi: 10.1016/j.hrthm.2013.07.047. [Epub ahead of print] 배경 브루가다증후군은젊은남성에서주로발생하고심실빈맥에의해서심장돌연사가일어나는유전질환이다. Milrinone과 cilostazol 등의 phosphodiesterase (PDE) 3 억제제는 L type calcium current (ICaL) 를증가시키고세포내 camp 농도를상승시킨다. Cilostazol 은혈소판응집을억제하며혈관을확장시키고특히다리쪽혈관을확장시킨다. 그렇기때문에 cilostazol은간헐적파행 (intermittent claudication) 그리고뇌혈관동맥경화증과뇌졸증의 2차예방에사용된다. Milrinone은심부전증에사용하며, camp를증가시켜서심부전증심장의수축력을증가시키고혈관확장 기능이있다. 이연구는브루가다증후군에서 milrinone 을 cilostazol 대신사용할수있을것으로생각되어 milrinone의사용가능성에대해알아보았다. 방법 관상동맥관류를하는우심실 wedge preparation을이용하여 epicardial 그리고 endocardial site에서활동전위 (action potential, AP) 그리고 electrocardiographic 기록을시행하였다. Transient outward current (Ito) 활성제 NS5806 (5 μm) 그리고칼슘차단제 verapamil (2 μm) 을사용하여인위적으로브루가다표현형을유발하였다. Received: September 10, 2013 Accepted: September 28, 2013 Correspondence: Tae-Joon Cha, MD, PhD, Division of Cardiology, Department of Internal Medicine, Kosin University College of Medicine, 34 Amnam-Dong, Seo-Gu, Busan, 602-702, South Korea. Tel: 051-990-6105, Fax: 051-990-3047, E-mail: chatjn@gmail.com 결과 NS5806+verapamil 을투여하니 all-or-none repolarization 이 epicardium 어떤곳에서는발생하고또 26 The Official Journal of Korean Heart Rhythm Society

다른곳에서는발생하지않아서 epicardium의 ST분절상승, epicardial dispersion of repolarization (EDR), transmural dispersion of repolarization (TDR) 등의발생증가가일어나게되었다. 이런상태에서는 epicardial AP dome이유지되는곳에서 AP dome이유지되지않는곳으로 phase 2 reentry가발생하여선행하는박동과매우근접한시점에심실기외수축, 심실빈맥등이발생하였다. Epicardium의 AP dome의소실은 endocardium AP dome 사이에서 TDR이발생하게된다. 이런 EDR TDR 등이부정맥이잘발생하게되는위험한시점 (vulnerable window) 을만들게된다. 이런것을치유하기위해서는활동전위 2기에 inward calcium current 를활성화하게하면 AP dome이복원화되며부정맥발생을억제하게된다. PDE inhibitor 인 milrinone (2.5 μm) 혹은 cilostazol (5~10 μm) 을관상동맥으로관류시키니 epicardial AP dome을회복시키고, dispersion을감소시키며, 기외수축과심실빈맥을유발시키는 phase 2 reentry를소멸시켰다. Milrinone과 cilostazol은 inward calcium current를증가시키는효과가있어서심근의수축력을증가시키고심장박동을빠르게한다. 심장박동수가빨라지면간접적으로 Ito의감소를유발시키며, 특히 cilostazol은고농도에서직접적으로 Ito를억제시키는효과가있다. 결론 이연구는브루가다증후군의심전도적그리고부정맥적인표현인재분극의결함을반전시키기위해 cilostazol과 milrinone을사용할수있음을보여주었다. 이약들은우심실 epicardium에서 ICa를증가시켜서 AP dome을복원시키며우심실심근의전기적이질성 (heterogeneity) 의발생을억제시켰다. 그래서 PDE 3 inhibitor 특히 cilostazol 그리고 milrinone이브루가다증후군의치료약제로사용할수있음을실험적으로증명하였다. article REVIEW Vol.14 No.3 27

ECG & EP Cases Ventricular Tachycardia Originating from the Right Ventricular Outflow Tract Terminated by Steam Pop Ki-Hun Kim, MD Cardiology Division, Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea Abstract Steam pops occur when tissue temperature exceeds 100 C. This can lead to tissue disruption and sometimes subsequent cardiac tamponade, especially in thin-walled structures such as the right ventricular outflow tract (RVOT). This event is potentially disastrous; however, in our case, ventricular tachycardia originating from the RVOT was successfully terminated by a steam pop, although it required pericardiocentesis and drainage. Key words: catheter ablation complication ventricular tachycardia Introduction Steam pops are infrequent in radiofrequency (RF) ablation for ventricular tachycardia (VT); although they have been reported to occur in only 1~1.5% of all RF ablations, they can cause cardiac tamponade, especially in the right ventricular outflow tract (RVOT). 1-3 Case Report Received: July 19, 2013 Accepted: September 28, 2013 Correspondence: Ki-Hun Kim, MD, Division of Cardiology, Department of Internal Medicine, Inje University College of Medicine, Busan, Korea Tel: 82-51-797-3010, Fax: 82-51-797-3009 E-mail: iron9411@gmail.com A 57-year-old woman presented to our emergency department with a 1-week history of waxing and waning palpitations that worsened and persisted on the day of admission, with associated dizziness and chest discomfort. Hypertension had been diagnosed 2 years earlier and was controlled by an angiotensin receptor blocker. Her family and social history were unremarkable. Her initial blood pressure (BP) was 130/98 mmhg, with a pulse rate of 170 beats/min and a respiration rate of 22 breaths/min. Her electrocardiogram showed a wide QRS tachycardia with left bundle branch block morphology, inferior axis, QRS width 140 ms, avl size slightly greater than avr, and a small r wave of 0.2 mv in the V2 lead, which suggested that the tachycardia originated from the left superior free wall of the RVOT (Figure 1). Rapid administration of intravenous adenosine and slowly repeated infusions of diltiazem and verapamil had no effect. After 28 The Official Journal of Korean Heart Rhythm Society

ECG & EP Cases Figure 1. Initial electrocardiogram of the ventricular tachycardia originating from the right ventricular outflow tract A B Figure 2. A, Catheter tip position on the ablation success point, targeting the ventricular tachycardia originating from the right ventricular outflow tract. Right anterior oblique view (30 ). B, 3D electroanatomic mapping shows that the focus of ventricular tachycardia originated from the right ventricular outflow tract. sedation, biphasic direct cardioversion (50 J) was performed twice; however, the tachycardia continued, and her BP dropped to 70/56 mmhg. A flecainide infusion was started, and the tachycardia stopped during that infusion. Laboratory test results were within normal limits, and a transthoracic echocardiogram showed normal left ventricular ejection fraction (64%) and mild Vol.14 No.3 29

ECG & EP Cases Figure 3. Electrogram when the ventricular tachycardia originating from the right ventricular outflow tract was terminated. Presystolic potential at the ablation catheter (ABLd) was earlier than the surface QRS onset at lead V2 by approximately 22 ms. Figure 4. Electrogram when the steam pop developed 30 The Official Journal of Korean Heart Rhythm Society

ECG & EP Cases Figure 5. Final electrogram after the steam pop showing sinus rhythm mitral regurgitation (grade I). The next day, an electrophysiology study was performed. With the patient fasting and unsedated, a 6 Fr quadripolar catheter was placed in the right ventricular (RV) apex and a 7 Fr deflectable non-irrigation catheter (Celsius TM, Biosense Webster, Diamond Bar, CA, USA) via an SR-0 sheath (St. Jude Medical, St. Paul, MN, USA) was placed in the RVOT via the right femoral vein. After performing an angiogram of the RVOT area, 3D electroanatomic mapping (Ensite TM, St. Jude Medical) was performed. The baseline rhythm was sinus with occasional ventricular premature contractions (VPC), whose morphology was compatible with the clinical VT. VT originating from the RVOT (cycle length 400 ms) was repeatedly induced by the RV burst pacing. The earliest ventricular potential was recorded at the left-superior area between the free wall and septum of the RVOT, and pace-mapping showed an identical VT morphology. The presystolic potential at the ablation catheter was earlier than the surface QRS onset at lead V2 by approximately 22 ms, and the 3D mapping point was compatible with the point. During RF ablation at the point on the VT state, VT was successfully terminated (Figures 2 and 3). However, some VPCs and non-sustained VTs remained after several additional ablations, which might have been associated with improper power delivery because of impedances and temperature limitations. Therefore, we changed the ablation catheter to a 7 Fr unidirectional irrigated form (Celsius TM Thermocool, Biosense Webster) for increased power delivery. RF ablation (45 W, with the maximum catheter tip temperature set to 50 C) was repeated at the same ablated site. Catheter irrigation was started automatically at a flow rate of 30 ml/min at the start of the ablation. During ablation, a sudden audible steam pop developed (Figure 4). Energy delivery was immediately stopped after the pop occurred. However, the patient s BP suddenly dropped and she became stuporous. After confirmation of cardiac tamponade by Vol.14 No.3 31

ECG & EP Cases portable transthoracic echocardiography, pericardiocentesis with drainage was performed. After drainage, the patient s BP improved to 100/70 mmhg. Fortunately, after this event, no more VPCs or VTs were observed for 30 min (Figure 5). We finished the procedure, keeping the pericardial drainage in place. After 3 days of supportive care, she was discharged. There were no further events over the 2-year follow-up period. Discussion RF ablation causes lesion development by inducing cell death when tissue temperature exceeds 50 C; however, it can also cause steam pops when the tissue temperature is 100 C, sometimes far exceeding the catheter tip temperature. 1,3 When steam explosions occur, which maybe audible as steam pops, they can cause cardiac perforation. This dangerous situation occurs more commonly in the RV than in the left ventricle because of the thin-walled structure of the RV. 2,4 Externally irrigated RF ablation can cool the catheter-tissue interface, making it possible to increase power delivery and reduce coagulum formation. However, irrigated RF also causes an imbalance between tissue and catheter tip temperatures during ablation, causing difficulty in predicting steam pops. 3 Cooper et al. found a relationship between pops and electrode temperature during atrial ablation and recommended maintaining a catheter tip temperature 40 C to prevent steam pops. 5 However, steam pops were observed when the mean catheter tip temperature was 39 C with open irrigation and even occurred with catheter tip temperatures as low as 34 C. 1 Yokoyama et al. demonstrated that steam pops occurred more frequently as power was increased from 30 to 50 W. 6 Hsu et al. suggested that pops occurred when power exceeded 48 W, and pop formation was limited when power remained under 42 W. 7 However, Seiler et al. showed no significant difference between power settings for lesions with and without pops, and found that limiting RF power to achieve an impedance decrease of 18 Ω is a feasible method of reducing steam pops. 1 Nonetheless, higher maximum energies and larger impedance falls are associated with steam pops. 4 Koruth et al. demonstrated that steam pops can be predicted by the rate of temperature rise and the maximum volumetric temperature measured by microwave radiometry during irrigated RF ablation. 3 Increasing contact force also was proportionally associated with more steam pops. 8 In our case, the relatively high power (45 W) and technically increasing contact force may have been related causes of the steam pops, but we could not check the spike in impedance because of the unstable situation. Whether the VT focus was abolished by elevated RF power delivery or the steam pop, the interpretation was tangled. Anyway careful handling of the ablation catheter and monitoring of impedance and catheter tip temperature, and possibly a low power setting, is required to prevent steam pops. References 1. Seiler J, Roberts-Thomson KC, Raymond JM, Vest J, Delacretaz E, Stevenson WG. Steam pops during irrigated radiofrequency ablation: feasibility of impedance monitoring for prevention. Heart Rhythm. 2008;5:1411-1416. 2. Tokuda M, Kojodjojo P, Epstein LM, Koplan BA, Michaud GF, Tedrow UB, Stevenson WG, John RM. Outcomes of cardiac perforation complicating catheter ablation of ventricular arrhythmias. Circ Arrhythm Electrophysiol. 2011;4:660-666. 3. Koruth JS, Dukkipati S, Gangireddy S, McCarthy J, Spencer D, Weinberg AD, Miller MA, D'Avila A, Reddy VY. Occurrence of 32 The Official Journal of Korean Heart Rhythm Society

Steam Pops During Irrigated RF Ablation: Novel Insights from Microwave Radiometry. J Cardiovasc Electrophysiol. 2013 [Epub ahead of print]. 4. Tokuda M, Tedrow UB, Stevenson WG. Silent steam pop detected by intracardiac echocardiography. Heart Rhythm. 2012 [Epub ahead of print]. 5. Cooper JM, Sapp JL, Tedrow U, Pellegrini CP, Robinson D, Epstein LM, Stevenson WG. Ablation with an internally irrigated radiofrequency catheter: learning how to avoid steam pops. Heart Rhythm. 2004;1:329-333. 6. Yokoyama K, Nakagawa H, Wittkampf FH, Pitha JV, Lazzara R, Jackman WM. Comparison of electrode cooling between internal and open irrigation in radiofrequency ablation lesion depth and incidence of thrombus and steam pop. Circulation. 2006;113:11-19. 7. Hsu LF, Jais P, Hocini M, Sanders P, Scavee C, Sacher F, Takahashi Y, Rotter M, Pasquie JL, Clementy J, Haissaguerre M. Incidence and prevention of cardiac tamponade complicating ablation for atrial fibrillation. Pacing Clin Electrophysiol. 2005;28 Suppl 1:S106-109. 8. Yokoyama K, Nakagawa H, Shah DC, Lambert H, Leo G, Aeby N, Ikeda A, Pitha JV, Sharma T, Lazzara R, Jackman WM. Novel contact force sensor incorporated in irrigated radiofrequency ablation catheter predicts lesion size and incidence of steam pop and thrombus. Circ Arrhythm Electrophysiol. 2008;1:354-362. ECG & EP Cases Vol.14 No.3 33

ECG & EP Cases A case of left bundle branch block-shaped wide QRS complex tachycardia with diagnostic ambiguity on a surface Electrocardiogram Min-Soo Ahn, MD Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea Abstract A 78-year-old woman presented with palpitations and wide QRS complex tachycardia with left bundle branch block morphology on an electrocardiogram (ECG). The Brugada algorithm suggested that the tachycardia was supraventricular in origin. However, electrophysiological study showed that the tachycardia was ventricular in origin with 1:1 ventriculoatrial conduction. Here, we report a case of broad complex tachycardia with diagnostic ambiguity on a surface ECG. Key words: arrhythmia catheter ablation premature ventricular contraction a Introduction In cases of tachycardia with a broad QRS complex, it is important to differentiate between supraventricular tachycardia (SVT) and ventricular tachycardia (VT). Electrocardiogram (ECG)-based differential diagnoses include VT vs. SVT with aberrant conduction, pre-existing bundle branch block (BBB), intraventricular conduction disturbances, and pre-excitation. Several criteria have been described for differentiation between VT and SVT in the presence of a wide QRS complex. We report a case of wide QRS complex tachycardia with left BBB (LBBB) Received: July 7, 2013 Revision Received: August 28, 2013 Accepted: September 28, 2013 Correspondence: Min-Soo Ahn, MD, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, 162 Ilsan-dong, Wonju, 220-701. Korea. Tel: +82-33-741-0909 Fax: +82-33-741-1219 E-mail: ahnn0102@medimail.co.kr morphology and a retrograde P wave on the surface ECG. Case report A 78-year-old woman presented to our hospital with palpitations and chest discomfort. She had a 6-year history of non-st segment elevation myocardial infarction (MI); however, she had not received treatment. On physical examination, blood pressure, pulse rate, and respiratory rate were 94/63 mmhg, 171 bpm, and 18/ min, respectively. Echocardiography revealed an enlarged left ventricle (5.7 cm) and left atrium (5.0 cm) with preserved left ventricular systolic function (ejection fraction, 53%). There was moderate hypokinesia on the inferior wall from the base to the apex and from the mid-posterolateral wall to the apex of the posterolateral wall. 34 The Official Journal of Korean Heart Rhythm Society

A ECG & EP Cases B Figure 1. Initial surface 12-lead ECG (A) and the ECG after administration of diltiazem (B). A 12-lead ECG showed wide QRS tachycardia with LBBB morphology (Figure 1A). The duration of the QRS complex was 148 ms, and the axis was normal. RS complexes were observed in leads V2-3, and R to S intervals in those leads were 72 and 84 ms, respectively. A retrograde P wave was observed on the terminal portion of the QRS complex. There was no S wave in lead V1, and the duration of the S wave in lead V2 was 40 ms. In lead V6, there was only an R wave Vol.14 No.3 35