Overdrive suppression of conduction in the canine His-Purkinje system after occlusion of the anterior septal artery

N. Takahashi, R. F. Gilmour, D. P. Zipes

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

The purpose of these experiments was to determine whether overdrive suppression of conduction (OSC), i.e., transient worsening of conduction or development of atrioventricular block after cessation of rapid pacing, could be produced in the canine His-Purkinje system damaged by ligation of the anterior septal coronary artery and to investigate the responsible mechanism. We found that OSC occurred in vivo after rapid ventricular and His bundle pacing but not after atrial pacing, and that it occurred in vitro after rapid pacing from the left bundle branch but not after pacing from the proximal His bundle. OSC was related to the duration and cycle length of pacing. Lidocaine increased while verapamil reduced the duration of OSC in vivo. The mechanism responsible for the unidirectionality of OSC is not clear but is probably related to the geometry of the atrioventricular junction and the anterograde versus the retrograde activation sequence. Changes in regional myocardial blood flow, autonomic tone, hemodynamic variables, or ventricular function do not appear to be required to produce OSC, based on the demonstration of the phenomenon in vitro. The data suggest a time- and rate-dependent change in factors affecting conduction such as excitability or cell-to-cell coupling, possibly due to accumulation of intracellular cations such as calcium.

Original languageEnglish (US)
Pages (from-to)495-505
Number of pages11
JournalCirculation
Volume70
Issue number3 I
DOIs
StatePublished - Jan 1 1984

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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