Time course of vulnerability to fibrillation after experimental coronary occlusion

Abstract

The early time course of vulnerability of the ventricles to fibrillation after coronary artery occlusion was measured in 6 dogs. The duration of a train of 60 Hz stimuli with currents of 2 to 3 times the diastolic threshold was used as the measure of vulnerability to fibrillation. Within 2 minutes of coronary occlusion the duration of the train of 60 Hz stimuli inducing fibrillation fell by an average of 25 percent of control values. Five minutes after coronary occlusion the duration of the train was an average of 34 percent shorter than control values. In all animals, the duration of the train required to produce fibrillation began to increase 30 minutes after coronary occlusion and approached control values. The relation of these findings to the time course of arrhythmias in experimental infarction and the early high mortality rate in cases of infarction in man is discussed.