Apr 15, 2011

AV nodal dual pathway electrophysiology and Wenckebach periodicity

Journal of Cardiovascular Electrophysiology
Youhua Zhang, Todor N Mazgalev

Abstract

The precise mechanism(s) governing the phenomenon of AV nodal Wenckebach periodicity is not fully elucidated. Currently 2 hypotheses, the decremental conduction and the Rosenbluethian step-delay, are most frequently used. We have provided new evidence that, in addition, dual pathway (DPW) electrophysiology is directly involved in the manifestation of AV nodal Wenckebach phenomenon. AV nodal cellular action potentials (APs) were recorded from 6 rabbit AV node preparations during standard A1A2 and incremental pacing protocols. His electrogram alternans, a validated index of DPW electrophysiology, was used to monitor fast (FP) and slow (SP) pathway conduction. The data were collected in intact AV nodes, as well as after SP ablation. In all studied hearts the Wenckebach cycle started with FP propagation, followed by transition to SP until its ultimate block. During this process complex cellular APs were observed, with decremental foot formations reflecting the fading FP and second depolarizations produced by the SP. In addition, the AV node cells exhibited a progressive loss in maximal diastolic membrane potential (MDP) due to incomplete repolarization. The pause created with the blocked Wenckebach beat was associated with restorat...Continue Reading

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  • Citations7

Citations

Mentioned in this Paper

Biochemical Pathway
Heart Block
Periodicity
Action Potentials
Refractory Period, Electrophysiological
Structure of Atrioventricular Node
Electrophysiology (Science)
NODAL gene
Familial Mediterranean Fever
Catheter Ablation, Transvenous

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