Electrophysiological control of ventricular rate during atrial fibrillation

Thirteen anesthetized canine subjects (17-29 kg) were used to demonstrate t hat mild cervical left vagal stimulation could control ventricular rate eff ectively during atrial fibrillation (AF). Two studies are presented, The fi rst study used six subjects to demonstrate the inverse relationship between (manually applied) left vasal stimulation and ventricular excitation (R wa ve) rate during AF. As left vagal stimulation frequency was increased, vent ricular excitation rate decreased. In these studies, a left vagal stimulus frequency of 0-10 per second reduced the ventricular excitation rate from > 200/min to < 50/nlin. The decreasing Ventricular excitation rare with incr easing left vagal stimulation frequency was universal, occurring in all 26 trials with the six subjects. This fundamental principle was used to constr uct an automatic controller for use in the second study, in which seven sub jects were used to demonstrate that ventricular rate can be brought to and maintained within a targeted range with the use of an automatic (closed-loo p) controller, A 45-minute record of automatic ventricular rate control is presented. Similar records were obtained in all seven subjects.