Cardio-circulatory effects of beta-adrenergic blockade in organic heart disease. Comparison between propranolol and CIBA 39,089-Ba.

Abstract

In order to evaluate the risk of precipitating heart failure with beta-adrenergic blocking drugs, 34 patients with organic disease of the left heart were given either 5 mg propranolol or 5 mg CIBA 39,089-Ba [l-isopropylamino-3-(o-allyloxyphenoxy-2-propanol HC1], a new specific beta-receptor antagonizer, during the course of pre-operative catheterization. Propranolol slowed the heart rate by 16% at rest and 9% during exercise, and reduced the cardiac output by 15% at rest and 17% during exercise. While the left ventricular stroke work remained practically unchanged, there was a 4 mm Hg increase in pulmonary wedge pressure at rest and a 7 mm Hg increase during exercise following propranoloL This is evidence of a depressant effect of the drug on myocardial contractility. This effect was slight in well-compensated patients, but was considerable in patients with increased resting pulmonary wedge pressure. CIBA 39,089-Ba produced an effect similar to that of propranolol as regards heart rate, which was lowered by 15% atrestand 16% during exercise, but produced only a small induced bradycardia being to a large extent offset by a higher stroke output This drug did not significantly change the resting or exercising pulmonary wedge pressure even inseverly disabled patients in frank heart failure. CIBA 39,089-Ba is a potent beta-receptor blocker in terms of its negative chronotropic effect, but differs from propranolol in that it produces a significantly less conspicuous decrease in myocardial contractile force. This difference may be ascribed to the difference in the chemical structures of the 2 drugs.