TY - JOUR
T1 - Cholinergically mediated tachyarrhythmias induced by a single extrastimulus in the isolated canine right atrium
AU - Schuessler, Richard B.
AU - Grayson, Thomas M.
AU - Bromberg, Burt I.
AU - Cox, James L.
AU - Boineau, John P.
PY - 1992/11
Y1 - 1992/11
N2 - 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.
AB - 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.
KW - Atrial fibrillation
KW - Multiple wavelet hypothesis
KW - Reentrant tachyarrhythmias
UR - http://www.scopus.com/inward/record.url?scp=0026736842&partnerID=8YFLogxK
U2 - 10.1161/01.RES.71.5.1254
DO - 10.1161/01.RES.71.5.1254
M3 - Article
C2 - 1394883
AN - SCOPUS:0026736842
SN - 0009-7330
VL - 71
SP - 1254
EP - 1267
JO - Circulation research
JF - Circulation research
IS - 5
ER -