Beneficial effects of propranolol and digitalis on contraction and S-T segment elevation after acute coronary occlusion

Abstract Propranolol and digitalis each have limltations in acute myocardial infarction, the former because of negative inotropic effects and the latter because of increased ischemia. To evaluate their combined effects, ouabain (in a priming dose of 7.5 μg/kg body weight followed by 2 to 3 μg/kg per min intravenous infusion) and propranolol (1 mg/kg intravenously) were administered randomly in 22 open chest dogs after acute coronary occlusion, and changes were observed in epicardial S-T segment (10 to 14 sites) and local tension (strain gauge measurements). Heart rate was controlled by atrial pacing. After acute coronary occlusion, tension in the nonischemic zone decreased to 92.8 ± 3.4 percent of control level. Propranolol reduced It further to 67.3 ± 4.9 percent ( P P P P P P P P