Effect of acute administration of propranolol on ventricular function in hypertrophic obstructive cardiomyopathy...

Seventeen patients with hypertropic obstructive cardiomyopathy, were studied using non-invasive techniques before and after the intravenous injection of 5 mg propranolol. The folloeing were analysed: left ventricular ejection time index, derived from the carotid pulse and heart rate; the isovolumic relaxation time, derived from the apex cardiogram and phonocardiogram; the diastolic closure rate of the mirtal valve; and the left ventricular diameters, systolic and diastolic, both measured by echocardiography. Propranolol produced shortening of the isovolumic relaxation time, increase in both the diastolic closure rate of the mitral valve and left ventricular systolic and left ventricular diastolic diameters. These results show that propranolol increases the rate of filling and the volume of the left ventricle, indicating that an improvement in distensibility is produced by beta-adrenergic blockade.