Cholinergically mediated tachyarrhythmias induced by a single extrastimulus in the isolated canine right atrium

Richard B. Schuessler*, Thomas M. Grayson, Burt I. Bromberg, James Lewis Cox, John P. Boineau

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

239 Scopus citations

Abstract

Cholinergic agonists and vagal stimulation potentiate the inducibility of atrial fibrillation. To describe the activation patterns and determine the mechanisms that sustain cholinergic fibrillation, tachyanrhythmias were induced with a single extrastimulus in the isolated Krebs-Henseleit-perfused canine right atrium (n=11) at increasing concentrations of acetylcholine (from 10-7.5 to 10-4.5 M). Bipolar electrograms were recorded from 250 epicardial sites simultaneously during control conditions and during extrastimulation (S1S1, 300 msec; S1S2, effective refractory period+5 msec) with and without acetylcholine. Activation sequence maps were constructed from each recording. Without acetylcholine, no tachyarrhythmias were induced. With increasing concentrations of acetylcholine, the refractory period decreased, and nonsustained (<2 seconds) rapid repetitive responses were induced. At higher concentrations, a sustained (>2-minute) fibrillation was induced. Activation sequence maps revealed that the rapid repetitive responses were characterized by multiple reentrant circuits. The number of circuits and wavelets increased in a dose-dependent fashion. However, unexpectedly, this trend did not continue when the tachyarrhythmia became sustained. Instead, the reentry tended to stabilize to a small, single, relatively stable reentrant circuit. In conclusion, the data suggest that, in this model, below a critical level of refractory period (<95 msec) atrial reentrant circuits, unassociated with anatomic obstacles, can become stable and dominate activation.

Original languageEnglish (US)
Pages (from-to)1254-1267
Number of pages14
JournalCirculation research
Volume71
Issue number5
DOIs
StatePublished - Nov 1992

Keywords

  • Atrial fibrillation
  • Multiple wavelet hypothesis
  • Reentrant tachyarrhythmias

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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