Changes in Cardiac Refractory Period During Signalled Shock Avoidance in Dogs

The effect of training during an aversive conditioning schedule on the ventricular effective refractory period (ERP) and the occurrence of repetitive extrasystoles (RE) was investigated in 11 dogs. The ERP was decreased significantly at avoidance onset during the first 5 days of the experiment. but remained unaltered during the second 5 days of testing. The changes in ERP were most pronounced on the first day. REs were observed most during avoidance in the animal with the greatest decrease in ERP but inconsistently in other animals. The potential use of aversive Training procedures to study the role of neural factors in cardiac arrhythmias is discussed.