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

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

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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
Pages (from-to)1254-1267
Number of pages14
JournalCirculation research
Issue number5
StatePublished - Nov 1992


  • Atrial fibrillation
  • Multiple wavelet hypothesis
  • Reentrant tachyarrhythmias


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