Effect of long-term diltiazem treatment on central haemodynamics and exercise endurance in essential hypertension.

The effects of long-term treatment with diltiazem on blood pressure, central haemodynamics and exercise endurance were studied in 16 men (mean age 52 years) with essential hypertension. Intra-arterial pressure and heart rate (HR) were monitored continuously. Cardiac output (CO) was measured by Cardiogreen at rest (supine and sitting) and during 50 W, 100 W and 150 W bicycle exercise. Haemodynamic measurements were repeated after continuous bicycling at 150 W for 20 min or until exhaustion. After 1 year on diltiazem (mean daily dose 278 mg) intra-arterial pressure was reduced (P less than 0.001) in all situations (at rest sitting from 183/108 mmHg to 157/92 mmHg (14%] due to reduction in total peripheral resistance. HR was reduced at rest (7%) and during exercise (10%). Stroke volume tended to increase while CO was unchanged. Exercise time at constant workload increased by 25%. After a peak level, intra-arterial pressure fell by 3% to 5% (P less than 0.05) due to a decrease in total peripheral resistance both before and during diltiazem treatment. Stroke volume and CO remained unchanged during endurance exercise while HR showed a small increase. Thus, there was no reduction in the overall cardiac pump function after long-term diltiazem treatment, and blood flow during exercise was maintained.