Haemodynamic effects of acebutolol

Abstract

We studied the haemodynamic effects of acebutolol, administered in intravenous doses of 0.5 mg/kg and 1.0 mg/kg body weight, in 7 patients who had undergone coronary artery bypass surgery and in 4 patients who had cardiac transplants. Myocardial contractility and ventricular volumes were assessed by computerized fluoroscopic analysis of the motion of surgically implanted left ventricular intramyocardial markers. In both groups of patients, acebutolol reduced all 4 measured indices of contractility. The end-diastolic and end-systolic volumes were increased by 13 per cent and 16 per cent, respectively. There was a mean reduction of 8 per cent in cardiac output. The mean heart rate fell by 12 per cent. Blood pressure and stroke volume were not significantly affected. Considered separately, the surgical patients with normal cardiac innervation and the transplant patients with denervated hearts showed the same direction and magnitude of change in all haemodynamic measurements except cardiac output, which fell only in the bypass patients. These results suggest that, while acebutolol exerts a mild cardiac depressant effect, it can be administered safely to patients with normal cardiac function in intravenous doses of at least 1.0 mg/kg body weight resulting in peak serum levels of over 2000 ng/ml. Furthermore, cardiac autonomic nervous reflexes do not appear to alter the haemodynamic effects of acebutolol in man.