Hemodynamics in Treatment with Calcium Antagonists

Summary

The hemodynamic mechanisms responsible for increased blood pressure in the elderly differ greatly from the hemodynamic situation in younger patients. Recent data from our 20-year follow-up study on central hemodynamics in essential hypertension show that in elderly hypertensive subjects (aged 60–69 years with mean arterial blood pressure (MABP) of 113 mmHg), cardiac index (CI) was 42% lower than in young hypertensives (17–29 years) with the same MABP. Total peripheral resistance was 69% higher. During exercise, the blood pressure increased more steeply in the older group.

The hemodynamic changes induced by 5 different calcium antagonists were studied invasively at rest and during exercise in 76 patients aged 19–64 years with mild to moderate essential hypertension. Acute studies (nisoldipine and tiapamil) demonstrated that the initial fall in blood pressure was due to a marked decrease in total peripheral resistance and was associated with reflex tachycardia and an increase in cardiac output. During long-term treat¬ment the reflex tachycardia disappeared. Chronic studies with verapamil (n = 9), tiapamil (n = 18), diltiazem (n = 16), nifedipine (n = 15), and nisoldipine (n = 17) demonstrated that all compounds reduced blood pressure 10%-17% at rest and during exercise. In all drug therapy, the fall in blood pressure was associated with reduction in total peripheral resistance. No reduction in heart pump function at rest or during exercise was seen. Exercise heart rate was reduced on verapamil, diltiazem, and tiapamil, but was compensated with an increase in stroke volume.

Since calcium antagonists induce few biochemical side effects, do not disturb pulmonary function, and maintain total and regional blood flow, they are well suited for treatment of hypertension in the elderly. Due to a rapid initial effect, however, the first dose should be small.