Effects of chronic atenolol therapy on cardiovascular response to isometric exercise in essential hypertension.

Cardiovascular response to 2 min of isometric handgrip exercise at 50% of maximum voluntary contraction was studied echocardiographically in 10 essential hypertensives, before and during treatment with atenolol for a mean of 2 months. The patients responded with increases in heart rate, systolic and diastolic blood pressures, cardiac output and calculated triple product, no changes in stroke volume and total peripheral resistance, and decreases in ejection fraction, mean velocity of circumferential shortening and mean diastolic posterior wall velocity of the left ventricle before treatment. Chronic atenolol therapy attenuated the increases in heart rate, blood pressure and triple product, and the decreases in ejection fraction, mean velocity of circumferential shortening and mean diastolic posterior wall velocity of the left ventricle but resulted in a marked increase in total peripheral resistance. The pressure response and triple product rise in response to isometric handgrip exercise were also decreased. This suggests an obvious advantage to hypertensive patients who may, therefore, be protected from the risk of cardiovascular complications following isometric exercise.