Paired pacing after coronary artery ligation

Abstract

Experiments were designed to test the hazards and physiologic effects of paired pacing of the heart before and after coronary ligation. Sustained paired pacing was performed in 13 of 14 “normal” animals in which the left anterior descending coronary artery was identified but not ligated. The technique produced increased myocardial contractility, as manifested by augmented left ventricular dp/dt. Pacer-induced ventricular fibrillation occurred in 7 of 9 other dogs in which paired pacing was attempted after coronary artery ligation. In a third group of 14 dogs pretreated with propranolol, paired pacing was safely accomplished in 11 after coronary artery ligation. Propranolol did not interfere with the inotropic effects of paired pacing. Application of these data to the problem of the “power failure” syndrome associated with myocardial infarction is discussed.