Circulatory effects of propranolol and cardiopulmonary bypass

Clinical experience has indicated a high operative risk due to depressed ventricular function in certain patients receiving chronic oral propranolol therapy for control of the symptoms of obstructive coronary artery disease. This has led to the recommendation that propranolol be discontinued 2 wk prior to elective coronary bypass surgery [5]. However, the half-life of propranolol in man is less than 6 hr [3] and other workers have reported no significant difference in mortality rates when comparing coronary artery bypass graft patients who had chronic propranolol therapy discontinued 36-48 hr prior to surgery with graft patients who had never received propranolol[4]. Because of the large number of angina patients receiving propranolol, the increasing performance of emergency coronary artery bypass surgery, and the occasional occurrence of acute myocardial infarction after propranolol withdrawal [l] the residual effects of chronic propranolol therapy on cardiac function after induction of anesthesia and after cardiopulmonary bypass were further investigated.