[Evaluation of cardiac performance in the hypertensive patient. Effect of a beta-blocking agent: atenolol].

Cardiac output (isotopic dilution method) and systolic time intervals were studied in 11 sustained and 8 borderline essential hypertensive patients, before and after intravenous administration of atenolol, a potent beta-blocking agent. Atenolol decreased significantly (p less than 0.01) cardiac output and heart rate. In borderline hypertensives, the preejection periods were significantly reduced. Atenolol prolonged the preejection periods more significantly (p less than 0.01) in borderline than in permanent hypertensives. Non invasive hemodynamic technics enabled the cardiac performance to be evaluated in hypertensives and the contribution of neurogenic factors in borderline hypertension to be estimated.