Strong postganglionic vagal stimulation applied during simulated atrial fibrillation significantly reduced the mean ventricular rate from 234 to 92 bpm (P<0.001).
Does postganglionic vagal stimulation reduce ventricular rate during simulated atrial fibrillation in rabbit heart preparations?
Postganglionic vagal stimulation significantly slows ventricular rate during simulated atrial fibrillation by inducing acetylcholine-mediated depression of AV node conduction.
Absolute Event Rate: 92% vs 234%
p-value: p=<0.001
BACKGROUND: Postganglionic vagal stimulation (PGVS) by short bursts of subthreshold current evokes release of acetylcholine from myocardial nerve terminals. PGVS applied to the atrioventricular node (AVN) slows nodal conduction. However, little is known about the ability of PGVS to control ventricular rate (VR) during atrial fibrillation (AF). METHODS AND RESULTS: To quantify the effects and establish the mechanism of PGVS on the AVN, AF was simulated by random high right atrial pacing in 11 atrial-AVN rabbit heart preparations. Microelectrode recordings of cellular action potentials (APs) were obtained from different AVN regions. Five intensities and 5 modes of PGVS delivery were evaluated. PGVS resulted in cellular hyperpolarization, along with depressed and highly heterogeneous intranodal conduction. Compact nodal AP exhibited decremental amplitude and dV/dt and multiple-hump components, and at high PGVS intensities, a high degree of concealed conduction resulted in a dramatic slowing of the VR. Progressive increase of PGVS intensity and/or rate of delivery showed a significant logarithmic correlation with a decrease in VR (P<0.001). Strong PGVS reduced the mean VR from 234 to 92 bpm (P<0.001). The PGVS effects on the cellular responses and VR during AF were fully reproduced in a model of direct acetylcholine injection into the compact AVN via micropipette. CONCLUSIONS: These studies confirmed that PGVS applied during AF could produce substantial VR slowing because of acetylcholine-induced depression of conduction in the AVN.
Mazgalev et al. (Tue,) conducted a other in Atrial fibrillation (n=11). Postganglionic vagal stimulation (PGVS) vs. Baseline was evaluated on Ventricular rate (p=<0.001). Strong postganglionic vagal stimulation applied during simulated atrial fibrillation significantly reduced the mean ventricular rate from 234 to 92 bpm (P<0.001).