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Seventeen patients with hypertrophic obstructive cardiomyopathy, were studied using non-invasive techniques before and after the intravenous injection of 5 mg propranolol. The following were analysed: left ventricular ejection time index, derivedfrom the carotid pulse and heart rate; the isovolumic relaxation time, derived from the apex cardiogram andphonocardiogram; the diastolic closure rate of the mitral valve; and 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 offilling and the volume of the left ventricle, indicating that an improvement in distensibility is produced by beta-adrenergic blockade.Since the first description of hypertrophic obstruc-HOCM, using simple bedside non-invasive techtive cardiomyopathy (HOCM) or idiopathic hyper-niques, and see if these methods are sensitive trophic subaortic stenosis (Brock, 1957; Braunwald enough The acute effects of beta-adrenergic blockade HOCM. Eleven were women and six men. The with propranolol in HOCM suggest that it pro-diagnosis was proven by previous catheterization duces an improvement in distensibility and filling and angiocardiography. All patients stopped propranolol therapy 4 to 7 Propranolol has been thought to be the treatment days before the investigation, which was carried of choice (Hubner et al., 1973). out in the early afternoon with the patient lying Because most drug studies involve using invasive supine. techniques, they are not applicable for the repeated assessment of patients, and therefore the beneficial Non-invasive studies effects of propranolol in HOCM must be judged These were recorded using a 6-channel Cambridge mainly by symptomatic assessment of the patient Machine (model 72112, Cambridge Scientific In- (Cohen and Braunwald, 1967;Hubner et al., 1973). struments, England), at a paper speed of 100 mmThe purpose of the present paper is to study the per second. The sensitivity settings of the control acute effect of propranolol (5 mg intravenously) in study were used in the post-propranolol state.

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