REVEW ARTCLES doi: http://dx.doi.org/10.18501/arrhythmia.2015.036 박예민 가천대학교길병원심장내과 Papillary Muscle Ventricular Tachycardia Yae Min Park, MD Cardiology Division, Gachon University Gil Medical Center, ncheon, Korea Received: June 9, 2015 Revision Received: November 5, 2015 Accepted: December 15, 2015 Correspondence: Yae Min Park, MD Division of Cardiology, Gachon University Gil Medical Center 774-21 Namdong Daero, Namdonggu, ncheon, Republic of Korea, 405-760 Phone: 82-32-460-3054, Fax: 82-32-469-1906 E-mail: ypruimin@naver.com Copyright 2015 The Official Journal of Korean Heart Rhythm Society Editorial Board & MMK Co., Ltd. ABSTRACT The papillary muscles are potential sites of reentry that may contribute to the maintenance of ventricular arrhythmia in animal models. Recently, the papillary muscles in the left ventricle have been reported as an arrhythmogenic focus in patients with and without structural heart disease. Over recent decades, the introduction of new catheter ablation technology has led to improvements in treatment, and catheter ablation is often curative for idiopathic ventricular tachycardia, including papillary muscle ventricular tachycardia. This review discusses the current knowledge of ventricular tachycardia originating from the papillary muscles, and explores recent advances in ablation techniques. Key Words: Papillary Muscle Ventricular Tachycardia Catheter Ablation 서론 유두근 (papillary muscle, PM) 은전기적으로활동적인조직이기때문에 reentry가일어날수있으며, 심실빈맥및심실세동이지속되는데에기여한다는것이동물실험에서보고되었다. 1 이후 2008년 Doppalapudi 등이처음으로구조적심질환이없는환자에서후내측유두근 (posteromedial PM) 에서기인하는특발성심실빈맥을보고하였다. 2 현재좌심실의유두근에서기인하는심실빈맥은특발성심실부정맥의한종류로따로분류가되고있으며빈도는약 7% 정도로보고되고있다. 3 두개의승모판막은좌심실의앞쪽 (antero-lateral PM) 과뒤쪽 (postero-medial PM) 으로각각연결이되어있다. 유두근에서유발하는심실빈맥은 후내측유두근에서유발하는경우가훨씬흔하다. 심전도에서모양은우각차단형태를나타내며, 후내측유두근에서유발하는경우에는 frontal plane에서 superior axis 형태를보이며, 2 전외측유두근 (antero-lateral PM) 에서유발하는경우에는 inferior axis 형태를보이는경우가많았다 (Figure 1). 4 섬유속심실빈맥과의비교분석 유두근은해부학적으로전도시스템에관여하는구조물인좌심실의섬유속과인접해있어섬유속심실빈맥 (fascicular ventricular tachycardia) 과의감별진단이필요하며, 몇몇연구가발표되었다 (Table 1). 유두근에서기인하는 219
A B V2 V2 V3 V3 avr avr avl V5 avl V5 AVF V6 AVF V6 Figure 1. VT originating from postero-medial PM exhibited a right bundle branch block with superior axis QRS morphology (A) while VT from antero-lateral PM exhibited a right bundle branch block with inferior axis QRS morphology (B). PM, papillary muscle; VT, ventricular tachycardia. Table 1. Comparison of clinical, electrocardiographic and electrophysiological characteristics between PM VT and fascicular VT PM VT Fascicular VT Manifestation of arrhythmia Sustained VT<PVC or non-sustained VT PVC or non-sustained VT<Sustained VT Mechanism Abnormal automaticity or triggered activity Re-entrant ECG during arrhythmia QRS morphology RBBB RBBB QRS duration Longer Shorter qr or R rsr' Q wave in limb leads (-) (+) Response to verapamil (-) (+) nduction mode during EPS Spontaneously or during an infusion of isoproterenol or epinephrine Programmed electrical stimulation Recurrence rate after RFCA Relatively high Low High frequency potential preceding the earliest local ventricular electrogram (-) (+) ECG, electrocardiogram; EPS, electrophysiologic study; PM, papillary muscle; PVC, premature ventricular complex; RBBB, right bundle branch block; RFCA, radiofrequency catheter ablation; VT, ventricular tachycardia. 220
심실빈맥의경우환자연령이더많았다. 5 은대개 focal, non-reentrant 기전을가지기때문에지속성심실빈맥보다는조기심실수축또는비지속성심실빈맥의형태로많이나타나며, 전기생리학검사도중인위적인전기자극 (programmed electrical stimulation) 으로는유발되지않았다. 2 대신자발적으로발생하거나 isoproterenol 또는 epinephrine 주입으로유발되는경우가많았다. 해부학적으로인접해있기때문에심전도에서모양이비슷하게나타날수있으나, QRS 너비가의경우훨씬컸다 (150±15 msec vs. 127±11 msec). 3 세부적인심전도모양으로 lead 의경우에서는 qr 또는 R 형태인경우가많으나섬유속심실빈맥의경우에는 rsr 인경우가많았다. 또한에서는 lead 과 avl에서 Q wave가없는경우가많았다. 3 의 QRS의모양이약간씩변할수있는데, 이는유두근내부의복잡한구조물내에서다양한 exit site로인해나타날수있다. 치료 은섬유속심실빈맥과다르게 verapamil에효과가없었으며, class C 항부정맥약제에도효과가없는경우가많았다. 4 특발성심실부정맥중에서모양이단일형 (monomorphic) 이면서심한증상을유발하거나부정맥약제에효과가없는경우최근에전극도자절제술이많이행해지고있으며, 에서도근치적치료로전극도자절제술이많이시도되고있다. 시술방법으로는 activation mapping이유용했으며, pacemapping도도움이되었다. 하지만유두근에카테터를안정적으로접근하기가쉽지가않으며, 유발부위가심내막이아니라유두근의깊은내부인경우가많기때문에 pacemapping이잘맞지않는경우도있었다. 6 섬유속심실빈맥에서는성공적인시술부위에서항상 Purkinje 전위 (potential) 가보였지만에서는전도시스템이관여하지않기때문에보이지않는경우가많았다. 2,3 동리듬중에 Purkinje 전위가보인다하더라도심실부정맥이발생했을때에는섬유속심실빈맥과같이 Purkinje 전위가선행하는것이아니라심실근육에서기인하는전위 (ventricular potential) 가선행한다고보고하였다 (Figure 2). 2 또한 Purkinje 시스템이관여하지않기때문에정상동리듬중에는이완기전위가나타나지 않는경우가대부분이었다. 4 또한심실부정맥이있을때에선행하는심실전위가클수록전극도자절제술의성공률이높았는데, 이는부정맥을유발하는부위와의근접성이높기때문인것으로생각된다. 7 다른연구에서는 Purkinje 전위가보일수록성공률이높았다고하며, 전극도자절제술이실패한군에서심장자기공명영상촬영에서측정한유두근의무게가더컸다. 6 유두근의해부학적구조및심장이수축하는특징, 카테터의불안정성등으로인해전극도자절제술은쉽지않은경우가많다. 또한유두근아래쪽의심근은대개두꺼워실제로부정맥이유발되는부위가심장내막에서거리가상당히먼경우가많이때문에고주파전극도자절제술로충분히깊은병변을만들기어려운경우가많다. 따라서섬유속심실빈맥에비해성공률이낮은편으로보고되고있다. 4 대안으로 irrigated-tip 카테터또는 8 mm-tip 카테터등을사용하여에너지를 30 W부터시작해서점차적으로 50 W까지상향조정하면서저항 (impedance) 이 8-10 ohm 낮아지는지, 최대온도가 40 에도달하는지등을살펴보는방법이있다. 2 하지만 steam pop 또는심장내천공에대한주의가필요하다. 고주파에너지전달도중부정맥이유발이되면서카테터의안정성이떨어지는경우가많은데, 이때빈맥의주기보다좀더빠르게우심실을자극하면카테터의안정성에도움을줄수있다. 6 또한심장내초음파 (intracardiac echocardiography) 의사용이카테터의위치를확인하는데도움을줄수있다 (Figure 3). 시술후에는승모판막역류가발생하지않았는지심장초음파검사를시행해서체크해보아야한다. 4 결론 좌심실의유두근에서기인하는심실부정맥은특발성심실부정맥의한종류로빈도는약 7% 정도로보고되고있다. 심전도에서우각차단형태를나타내며, 조기심실수축또는비지속성심실빈맥으로많이나타난다. 치료로전극도자절제술을시행할수있으며, activation mapping 또는 pacemapping이유용하고, 심장내초음파의사용이성공률을높일수있다. 하지만유두근의수축하는특징, 카테터의불안정성등으로인해아직까지성공률에는제한이있으며, 향후더나은전극도자절제술결과를위해서는새로운테크닉의개발및연구가필요하다. 221
ABL d ABL p unipolar His d His m His p L2 LV34 LV56 LV78 LV910 L112 RVd RVP Figure 2. Activation mapping showing bipolar electrograms from distal bipoles of the ablation catheter (ABL d) at the site of earliest local activation during VT. The local ventricular electrogram recorded from the distal bipole of the ablation catheter preceded the onset of QRS by 30 msec. RF ablation at this site successfully terminated VT. During VT, high-frequency potentials likely representing the Purkinje network (red arrows) were recorded. However, it was not the earliest potential, suggesting that the conduction system was not directly involved in the tachycardia.,,, and are surface ECG leads; ABL d and ABL p are distal and proximal bipolar electrograms from the ablation catheter; His d, His m, and His p are proximal, mid, and distal bipolar His-bundle electrograms; and LV 1/2 through to 11/12 are bipolar electrograms recorded from the left ventricle, with the LV 3/4 pair located at the antero-lateral PM. ECG, electrocardiogram; LV, left ventricle; PM, papillary muscle; RF, radiofrequency; VT, ventricular tachycardia. LV Ablation catheter ALPM Figure 3. ntra-cardiac echocardiographic image of the successful ablation site. A 2-dimensional intra-cardiac echocardiographic image demonstrating that the ablation catheter was positioned at the ALPM. ALPM, antero-lateral papillary muscle; LV, left ventricle. 222
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