Time course of spontaneous ventricular arrhythmias following acute coronary occlusion in the dog

In this study, the arrhythmias occurring in dogs between 4 and 15 hr after occlusion of the left anterior descending coronary artery were continuously monitored by recording the electrocardiogram from bipolar leads. At 4.5 hr the number of dogs with less than 50% of sinus beats had increased and at 5 hr 15 min sinus beats represented on average 80% of total heart beats. In the period up to 6 hr isolated ventricular beats and ventricular salvos were seen in 95% and 63% of the dogs respectively and at 7 hr there were, on average, 50% of sinus beats and monomorphic ventricular rhythm was observed in 58% of the dogs. From 7 hr half the dogs had over 50% of ventricular ectopic beats and by 9 hr ventricular rhythm disturbances were permanently present in all the dogs. The ventricular arrhythmias reached a peak at about 11–12 hr (mean % sinus beats < 10) when all dogs had a predominantly monomorphic (42%) and/or polymorphic (63%) ventricular heart rhythm. The characteristic time course of these cardiac disturbances suggest that it may form the basis for an experimental model that may be useful in analyzing the effects of potential antiarrhythmic drugs.