Hemodynamic Effect of Bunitrolol on Patients with Ischemic Heart Disease

Comparison with Propranolol

Abstract

Acute hemodynamic changes induced by two beta-blocking agents, bunitrolol and propranolol, in patients with ischemic heart disease were studied.
Besides possessing negative chronotropic and inotropic effects which were demonstrated by decreased heart rate (HR), cardiac index (CI) and double product (DP) of the heart, propranolol significantly increased systemic vascular resistance (SVR, 12%, p<0.05) and the time constant of left ventricular (LV) isovolumic pressure fall (T, 10%, p<0.01). With bunitrolol, no significant changes were observed in indexes reflecting chronotropic and inotropic states of the heart, and CI and DP were essentially unchanged. Only LV systolic pressure (-5%, p<0.01), LV enddiastolic pressure (EDP, -17%, p<0.01) and T (-10%, p<0.05) decreased significantly. Systemic vascular resistance (SVR) decreased, though insignificantly.
Myocardial oxygen supply-demand balance in the resting state was not improved by propranolol as evidenced by the fact that CI decreased in proportion to the decline in DP. In contrast, ischemia at rest was apparently improved by bunitrolol because LV wall stress decreased due to the reduction in LV volume which was suggested by the decline in LV systolic pressure and LVEDP while CI remained constant. Improvement of the time constant T might be strong evidence of relief from ischemia.
Bunitrolol might be effective even in patients with overt heartfailure, especially that due to ischemic heart disease because of its lack of negative inotropic action and its ameliorating effect on ischemia at rest.