EP ROUNDS

Premature Ventricular Contractions with a RightBundle Branch Block and Inferior QRS AxisMorphology: Where is the Site of the Origin?TAKUMI YAMADA, M.D., JOSE F. HUIZAR, M.D., HUGH T. MCELDERRY, M.D.,and G. NEAL KAY, M.D.From the Division of Cardiovascular Diseases, University of Alabama at Birmingham, Birmingham, Alabama

A 63-year-old woman with symptomatic premature ventricular contractions (PVCs) underwent electro-physiologic testing. The PVCs were suggested to originate from the infra-aortic valvular left ventricularoutflow tract because the PVCs had S-waves in leads I, V5, and V6, and an R/S ratio >1 in lead V1. How-ever, during some PVCs without S-waves, the ST segment had negative retrograde P-waves with a longerventricularatrial (VA) interval. A Radiofrequency (RF) application in the left coronary cusp completelyeliminated the PVCs, suggesting that negative retrograde P-waves might have been observed as pseudoS-waves during the PVCs. (PACE 2007; 30:1009–1011)

premature ventricular contraction, coronary cusp, left ventricular outflow tract, radiofrequencycatheter ablation

Case PresentationA 63-year-old woman with symptomatic pre-

mature ventricular contractions (PVCs) was re-ferred for electrophysiologic testing (EPS) andcatheter ablation. A 24-Holter recording revealedmore than 14,000 PVCs and more than 1,300 PVCsin a bigeminal form. The PVCs had a right bundlebranch block configuration and right inferior QRSaxis (Fig. 1). Where is the site of the PVC origin?

CommentaryRadiofrequency (RF) catheter ablation has

been used for the ablation of idiopathic ven-tricular tachycardia (VT) and symptomatic PVCsoriginating from the left ventricular outflow tract(LVOT) as well as the right ventricular outflowtract (RVOT).1,2 Ventricular arrhythmias originat-ing from the LVOT are anatomically classified intotwo groups (those with a supraaortic valvular ori-gin vs. those with an infraaortic valvular origin).2,3

Though it has been reported that RF catheter abla-tion can be safely performed in the LVOT,1–3 seri-ous complications such as a chronic left main coro-nary artery occlusion4 or aortic regurgitation may

There was no financial support for this study.

Address for reprints: Takumi Yamada, M.D., Ph.D., Divisionof Cardiovascular Diseases, Cardiac Rhythm Management Lab-oratory, University of Alabama at Birmingham, VH B147,1670 University Boulevard, 1530 3rd AVE S, Birmingham, AL35294–0019. Fax: +1-205-975-4720; e-mail: takumi-y@fb4.so-net.ne.jp

Received February 21, 2007; accepted March 21, 2007.

occur. Simple mapping and a limited number ofRF applications may reduce the risk of those com-plications. Therefore, it is important to predict thePVC origin on the basis of the electrocardiographiccharacteristics before the catheter ablation.

Before the catheter ablation, the PVCs in thiscase were suggested to originate from the LVOT be-cause S-waves in lead I and an R/S ratio >1 in leadsV1 and V2 were observed in the PVC morphology. Ithas been reported that with PVCs originating fromthe LVOT, a right bundle branch block morphologyand S-waves in leads V5 and V6 can differentiatean infraaortic valvular origin from a supraaorticvalvular one.2,3 Using that criteria, the PVC mor-phology in this case suggested an origin below theaortic valve. During the EPS, frequent PVCs with atrigeminal form appeared spontaneously. The QRSmorphology of those PVCs had a left bundle branchblock configuration, inferior axis, and transitionzone between leads V2 and V3 (Fig. 2A). In our lab-oratory, the transition zone during the EPS some-times differed from that before the catheter abla-tion probably because the precordial leads werepositioned superior to the typical position, where acutaneous pad for extrathoracic cardioversion wasplaced. In this case, the QRS morphology in leadI recorded in the supine position during the EPSalso differed from that before the catheter ablation,probably because the ECG before the catheter ab-lation was recorded in the sitting position. Actu-ally, the prominent S-wave in lead I recorded be-fore the catheter ablation could not be reproducedanywhere in the LVOT during the EPS. After noearly activation was found in the RVOT duringthe PVCs, mapping of the LVOT was performed.Because S-waves in leads V5 and V6 predicted

C©2007, The Authors. Journal compilation C©2006, Blackwell Publishing, Inc.

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YAMADA, ET AL.

Figure 1. Twelve-lead ECG during trigeminal premature ventricular contractions (PVCs).

Figure 2. Cardiac tracings showing (A) the pseudo S-waves (arrowheads) and (B) the negativeretrograde P-waves (arrows) and successful ablation site. ABL (His, RV)-D, P = the distal andproximal electrode pairs of the ablation (His bundle, right ventricular) catheter.

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PVCs WITH PSEUDO S-WAVE

an infraaortic valvular PVC origin, mapping belowthe aortic valve was performed first. However, noearlier activation than the onset of the QRS wasfound below the aortic valve. Next, after perform-ing a coronary artery angiogram, mapping in theaorta above the aortic valve was performed. Fol-lowing that, some PVCs without any S-waves inleads V5 and V6 were observed (Fig. 2B). Duringthose PVCs, negative retrograde P-waves with alonger VA interval than during the PVCs with S-waves in leads V5 and V6 were observed in theST segment. During pace mapping in the left coro-nary cusp, decremental VA conduction provokedby rapid ventricular pacing demonstrated a QRSwithout S-waves in leads V5 and V6 and negativeretrograde P-waves in the ST segment. The earliestlocal activation preceding the onset of the QRS by

20 ms was found in the left coronary cusp duringthe PVCs (Fig. 2B). An RF application to that sitecompletely eliminated the PVCs.

S-waves in leads V5 and V6 can be a reliablepredictor for differentiating a PVC origin below theaortic valve from that above the aortic valve.2,3

However, the negative retrograde P-waves wererecognized as pseudo S-waves in leads V5 andV6 in this case. Therefore, careful observation ofall the leads in the 12-lead ECG will be neededto avoid missing a pseudo S-wave. Recording theatrial electrograms in the His bundle region shouldalso be performed during the mapping of the VT orPVCs originating from the LVOT. Rapid ventricularpacing may be useful for separating the pseudo S-waves from the QRS in cases with a fast retrogradeVA conduction.

References1. Ouyang F, Fotuhi P, Ho SY, Hebe J, Volkmer M, Goya M, Burns M, et al.

Repetitive monomorphic ventricular tachycardia originating from theaortic sinus cusp: Electrocardiographic characterization for guidingcatheter ablation. J Am Coll Cardiol 2002; 39:500–508.

2. Ito S, Tada H, Naito S, Kurosaki K, Ueda M, Hoshizaki H, MiyamoriI, et al. Development and validation of an ECG algorithm for identify-ing the optimal ablation site for idiopathic ventricular outflow tracttachycardia. J Cardiovasc Electrophysiol 2003; 14:1280–1286.

3. Hachiya H, Aonuma K, Yamauchi Y, Harada T, Igawa M, Nogami A,Iesaka Y, et al. Electrocardiographic characteristics of left ventricularoutflow tract tachycardia. Pacing Clin Electrophysiol 2000; 23:1930–1934.

4. Pons M, Beck L, Leclercq F, Ferriere M, Albat B, Davy JM. Chronicleft main coronary artery occlusion: A complication of radiofrequencyablation of idiopathic left ventricular tachycardia. Pacing Clin Elec-trophysiol 1997; 20:1874–1876.

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