Abnormalities of Left Ventricular Contraction Induced by Beta Adrenergic Blockade

To understand better the hemodynamic effects caused by propranolol, its effect on the geometry of left ventricular contraction was studied in ten subjects, four with angiographic evidence of coronary artery disease and six without demonstrable heart disease. Heart rate was controlled in four subjects with right atrial pacing. After 5 mg of intravenous propranolol, there were decreases in heart rate and cardiac index in most subjects with a variable effect on left ventricular end-diastolic pressure.Left ventricular end-diastolic volume increased in the majority of instances with a reduction in both volume ejected and per cent circumferential fiber shortening of the left ventricle. Furthermore, after propranolol the left ventricle assumed a more elongated shape. Propranolol either induced or exaggerated asynergy in five subjects, three of whom had coronary heart disease. These changes provide a morphologic basis for some of the cardiac hemodynamic effects of propranolol.