Ventricular Tachycardia with AlternateVentriculo-atrial Wenckehach Conduction Dueto Two-level Block

MICHAEL WEHR*, PEDRO BRUGADA. MARTIN GREEN**, HOSHIARABDOLLAHt, and HEIN JJ. WELLENSFrom the Department of Cardiology, Annadal Hospital, University of Limburg, Maastricht,The Netherlands

WEHR, ET AL.: Ventricular tachycardia with alternate ventriculo-atrial Wenckehach conduction due totwo-level block. A 54-year-oJd patient was studied because of ventricular tachycardia following aninferior myocardial infarction. During one episode o/non-sustained ventricular tachycardia a 9:4 al-ternating ventriculo-atrial Wenckehach block was noted. This was based upon a 2:1 block between theventricles and the bundle of His and a 5:4 Wenckebach block between the bundle of His and the atria.Our study shows that alternate Wenckebach periods during ventricuio-atriaj conduction may be causedby two or more levels of block in the ventriculo-atrial conduction system. [PACE, Vol. 7, March-April,1984)

ventricular tachycardia, alternating Wenckebach conduction.

Some form of ventriculo-atria! conduction occursin approximately 50% of patients with clinicallyoccurring ventricular tachycardia studied by pro-grammed stimulation of the heart.^ An interestingtype of ventriculo-atrial conduction has beendescribed^^ which shows progressive lengtheningof the ventriculo-atrial conduction time of everyalternate conducted beat until the sequence ter-minates with two or more blocked ventricular beats.We recently studied a patient with ventriculartachycardia in whom a 9:4 ventriculo-atrial blockcould be attributed to block at two different levelsof the ventriculo-atrial conduction system.

Case Report

The patient was a 54-year-old male who devel-oped ventricular tachycardia two weeks after an

•Supported by the Deutsche Forschungsgemeinschaft.

*''Fellow of the Medical Research Council of Canada.

tResearch Fellow of the Ontario Heart Foundation.

Address for reprints: Hein J. ]. Wellens, M.D., Department ofCardiology. Annadal Hospital, Postbus 1918, 6201 Bx Maas-tricht/The Netherlands.

Received March 2, 1983: revision received August 9, 1983:accepted August 10, 1983.

inferior myocardial infarction. The arrhythmiacould not be controlled by oral treatment withamiodarone and procainamide. Following in-formed consent an electrophysiological study wasperformed in the resting postabsorptive. non-se-dated state while the patient was still on amio-darone and procainamido. Using the femoral ap-proach four quadripolar catheters were introducedand positioned respectively in the right ventric-ular apex, the tricuspid valve ring, the coronarysinus and retrogradely over the aortic valve into aleft ventricular aneurysm. Our methods of pro-grammed stimulation and of recording and anal-ysis of tracings have previously been described.""

Electrophysiological Study

During sinus rhythm the AH interval was 150ms and the HV interval was 50 ms. Using the ex-trastimulus technique during right atrial pacing ata basic pacing cycle length of 600 ms, dual AVnodal pathways were demonstrated in the anter-ograde direction. The effective refractory periodswere 390 ms for the fast AV nodal pathway and350 ms for the slow AV nodal pathway. The an-terograde effective refractory period of the His-Purkinje system was shorter than the functional

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WEHR. ET AL.

refractory period of the fast AV nodal pathway of420 ms. Single test stimulation during right apicalventricular pacing with a basic cycle length of 620ms revealed a discontinuous ventriculo-atrial con-duction curve with an atrioventricular echo-heatat a coupling interval of 370 ms using the slowAV nodal pathway in the retrograde and a fast AVnodal pathway in the anterograde direction. Bun-dle branch reentrant beats were seen at couplingintervals of 430 and 330 ms. The effective refrac-tory period of the His-Purkinje system in the re-trograde direction was less than the functional re-fractory period of the right ventricle of 260 ms.The maxima! V2-H2 interval was 280 ms and themaximal H2-A2 interval was 260 ms.

Two different types of ventricular tachycardiawith similar morphology but different cycle lengthswere initiated by two ventricular premature beatsduring right ventricular apical pacing with a basicpacing cycle length of 620 ms: a sustained ven-tricular tachycardia with a cycle length of 350 ms,a right axis deviation and a right bundle branchblock-like morphology was initiated by two ven-tricular premature heats with premature heat in-tervals of 230 ms each. This arrhythmia could beterminated by two ventricular premature beats with

premature beat intervals of 290 ms and 190 ms,respectively.

A non-sustained ventricular tachycardia with acycle length of 240-250 ms, a right axis deviationand a right hundie branch block-like morphologywas initiated hy two ventricular premature beatswith premature beat intervals of 240 ms each (Fig.1), The morphology of this tachycardia was similarto that of the clinical episodes. There was a regular2:1 relationship between the ventricular electro-grams in the right ventricular lead [RV) and thepotentials of the bundle of His in the His-bundlerecording. Between these signals and the atrial sig-nals in the coronary sinus lead there was a 5:4Wenckehach conduction resulting, altogether, ina 9:4 ventriculo-atrial block. Figure 2 shows atgreater magnification that the retrograde alternat-ing Wenckebach sequence terminates with blockbetween the bundle of His and the atria. AlternateWenckehach conduction was not ohserved duringprogrammed right apical ventricular pacing (sin-gle test stimulation) and overdrive pacing; how-ever, we did not pace at a rate similar to the oneduring ventricular tachycardia. The sequence ofatrial activation during ventricular tachycardia wassimilar to that during right ventricular pacing.

Figure 1. Initiation of ventricular tachycardia during right ventricular pacing at a basic pacingcycle length of 620 ms by 2 ventricular premature b<;ats at premature-beal intervals of 240 ms.Six surface leads were simultancousiy recorded with the endocavitury eiectrograms from theright ventricle (RV). two different sites of the left ventricular aneury.sm (LV 10, LV 12], coronarysinus (CS) and (he bundle of His (His). As discussed in the texl and further explained by aladder diagram in Fig. 2. there was 2:1 V-H and a 5:4 U-A relationship during tachycardiaresulting in a 9:4 ventriculo-atrial block.

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ALTERNATE WENCKEBACH CONDUCTION IN VENTRICULAR TACHYCARDIA

Discussion

Alternating Wenckebach conduction has heenshown to occur within the atria, the AV node, theleft bundle and right bundle, the Kent hundle andthe bundle of His.^ Block at different levels hasbeen postulated as the mechanism for this phe-nomenon.'*'̂ Levy et aF could induce anterogradealternate Wenckebach periods during right atriaipacing in 80.5% of 36 patients and decided thatthe site of block was in the AV node. The highincidence of this finding suggests that alternateWenckebach periodicity in the AV node may be aphysiologic phenomenon. Castellanos et ai" dem-

onstrated tbe presence of two- or three-level blockin different parts of the conduction system. Duringright atriai pacing at rapid rates an intra-atrialWenckebach pattern of stimulus-to-response in-tervals coexisted with distal AV nodal and His-Purkinje block. Although Halpern et aP suggestedthat some alternating Wenckebach periods couldhe due to a single level of block, most authors agreethat two levels of block usually occur in one struc-ture.

There are few reports about retrograde alternateWenckebach conduction. Levy et al reported 3 casesof pacing-induced retrograde alternate Wencke-bach periods. In only one of their patients could

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Figure 2. Part o/ i\\e sequence o/events s\\o^NT\ in Fig. ]. As shown in the laddei diagram thealternating Y^enckehach sequence terminates wiih block befween Xhe bundle of His and the atvia.The HHintervai o/510 ms mighl be explained by some degree o/functionaJ bJock thai occurredsponlaneousiy during ventricular Xachycaxdia.

824203'

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WEHR, ET AL.

the site of block be localized within the AV node.^Castillo et al demonstrated a two-level AV blockin two anatomically different structures both inanterograde and retrograde direction during atriaiand ventricular pacing.-̂

To our knowledge, retrograde alternatingWenckebach conduction and the exact localiza-tion of two levels of block in two different struc-tures have not been descrihed during ventriculartachycardia. Thanks to multiple endocavitary re-cordings during tachycardia we were able to showa 2:1 block in the specific conduction system be-tween the ventricles and the bundle of His and a

5:4 Wenckebach conduction between the bundleof His and the atria, probably within the AV node.

Theoretically, retrograde alternate Wenckebachcan also be based upon longitudinal dissociationof the bundle of His. the AV node or both.^"" Bothdual AV nodal pathways and AV nodal echo heatswere demonstrated in our patient during pro-grammed right ventricular stimulation. Because ofthe short episode of ventricular tachycardia, wecould not study this possibility further. However,our patient clearly showed two levels of hlock be-tween the ventricles and the atria during this ep-isode of ventricular tachycardia.

References

Wellena. H.).)., Bar. F.W.. and Lie. K.I.: The valueof the electrocardiogram in the differential diag-noses of a tachycardia with a wide QRS complex.Am. /. Med.. 64:27. 1978.Levy, S., Roudaut. R., Bouvier. E.. et al.: Alternateventriculoatrial Wenckebach conduction. Circu-lation, 61:648, 1980.Castillo, C. Maytin. O.. Castellanos. A.: His bundlerecordings in atypical AV nodal Wenckebach blockduring cardiac pacing. Am./. Cardiol., 27:579.1971.Ross, D.L., Farr6, |.. Bar, F.H..etal.: Comprehensiveclinical electrophysioiugic studies in the investi-gation of documented or suspected tachycardias.Time, staff, problems, and costs. Circuiation,61:1010. 19H().Schamroth. L.: The Disorders of Cardiac Rhythm.Oxford, Blackwell Scientific Publications. 1980, p.184.Katz, L.N.. and Pick, A.: Clinical Elecirocardiog-rtiphy. Part I. The Arrhythmias. Philadelphia, Lea& Febiger. 1956, p. 413.

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Levy. S.. Pouget, B., Clementy, J., et al.: Pacing-induced alternate Wenckebach periods, (abstr.)Transactions of the First Joint Meeting of the Work-ing Croups of the European Society of Cardiology,Brighton, June 22-25, 1978.Castellanos, A., Sung. R.J., Mallon, S.M.. et al.:Effects of proximal intra-atrial Wenckebach on dis-tal atrioventricular nodal and His-Purkinje block.Am. Heart /.. 95:228. 1978.Halpern. M.S., Nau, G.J., et al.: Wenckebach pe-riods of alternate beats. Clinical and experimentalobservations. Circulation, 48:41. 1973.Myerburg. RJ., Nilsson, K., Befeler. B.. et al.:Transverse spread and longitudinal dissociation inthe distal A-V conducting system. /. Ciin. Invest.,52:885. 1973.Schuilenburg, R.M,: Ob.servutions on Alrioventric-uiar Conduction in Man Using Intracardiac EJec-frocardiography and StimuJafion. Thesis, Amster-dam. 1974.

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