Abstract

Intravenous injections of 20-25 mg. d-propranolol did not change the heart rate or systemic pressure in 13 patients with cardiac infarction. Cardiac output was depressed in 10, but there was no clinical deterioration. d-Propranolol was better tolerated than dl-propranolol under these conditions and justifies further investigation as an anti-dysrhythmic agent. The major depressant effects of dl-propranolol following cardiac infarction appear to be due to beta-adrenergic blockade and not to a direct depressant action on cardiac muscle.