Suppression of atrial fibrillation by multisite and septal pacing in a novel experimental model

To evaluate the preventive efficacy of multisite and septal atrial pacing in an experimental model.

Sterile right atrial pericarditis was induced in 12 foxhounds to provide an anatomical substrate for atrial fibrillation (AF). As a trigger mechanism, atrial extrasystoles were simulated by constant asynchronous pacing at a cycle length of 1000 ms from randomly selected right or left atrial electrodes, using a biatrial epicardial multielectrode with 128 bipoles. Additionally, a transvenous pacing lead was screwed into the interatrial septum. Four electrodes located in the high and low right (HRA/LRA) and left atrium (HLA/LLA) were selected for preventive multisite stimulation. Constant pacing at a cycle length 30 ms below sinus rate was applied from the following site(s): HRA, septal, HRA+LRA, HRA+LLA, HRA+LRA+LLA and HRA+LRA+HLA+LLA (order randomized). Number and duration of AF episodes were studied during 10 min intervals, separated by 5 min pauses, respectively. To validate the model, the protocol was repeated 10 min after i.v. bolus administration of D,L-sotalol (1 mg/kg body weight).

The number of AF episodes decreased with increasing number of pacing sites, reaching statistical significance compared to HRA stimulation for quadruple-site and single-site septal pacing only (P<0.05). Single-site septal was as efficient as quadruple-site pacing in suppressing AF. The duration of AF episodes was not significantly affected by the pacing configuration. D,L-sotalol almost completely suppressed AF irrespective of the pacing configuration used.

In this novel experimental model, quadruple-site and septal pacing effectively suppress paroxysmal AF.