Cholinergically Mediated Tachyarrhythmias Induced by a Single Extrastimulus in the Isolated Canine Right Atrium
作者:
Richard Schuessler,
Thomas Grayson,
Burt Bromberg,
James Cox,
John Boineau,
期刊:
Circulation Research
(OVID Available online 1992)
卷期:
Volume 71,
issue 5
页码: 1254-1267
ISSN:0009-7330
年代: 1992
出版商: OVID
关键词: atrial fibrillation;multiple wavelet hypothesis;reentrant tachyarrhythmias
数据来源: OVID
摘要:
Cholinergic agonists and vagal stimulation potentiate the inducibility of atrial fibrillation. To describe the activation patterns and determine the mechanisms that sustain cholinergic fibrillation, tachyarrhythmias were induced with a single extrastimulus in the isolated Krebs-Henseleit-perfused canine right atrium (n=11) at increasing concentrations of acetylcholine (from 10−7.5to 10−4.5M). 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 nonsus-tained (<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.
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