Regular Endurance Exercise Decreases Susceptibility to Ventricular Fibrillation during Acute Ischemic Events

Abstract

Regular physical activity is often associated with a decreased incidence of sudden cardiac death (1–3). Since long-term participation in exercise programs is difficult to achieve, it has not been possible to confirm whether these results were due to a beneficial effect of the physical activity itself or whether it was a consequence of selfselection of those engaging in regular exercise. To examine the role of regular exercise in the prevention of sudden cardiac death we studied the effects of a two-month exercise program on the incidence of ventricular fibrillation after acute ligation of a coronary artery in domestic Yorkshire pigs. The latter was chosen as the experimental animal, since its coronary circulation is similar to that of man and because of its high susceptibility to ventricular fibrillation after sudden interruption of myocardial perfusion. Results were compared with those of a sedentary group. Some animals of both groups were subjected to an atrial pacing test and (or) to a brief graded coronary artery constriction prior to ligation of the coronary artery to evaluate the influence of the exercise program on cardiovascular performance.