Hemodynamic effects of calcium channel blockers at rest and during exercise in essential hypertension
The main hemodynamic disturbance occurring in patients with essential hypertension is an increase in the total peripheral resistance. In young patients with hypertension, this disturbance is clearly seen during muscular exercise, even though the calculated resistance might be normal during rest. This article reports results of studies on the long-term hemodynamic effects of two calcium channel blockers, verapamil and nifedipine, in patients with mild to moderate hypertension. Twenty-five men, aged 20 to 64 years, with diastolic blood pressures between 100 and 120 mm Hg before treatment were studied at rest and during exercise on ergometer bicycles. Blood pressure was recorded intra-arterially, and cardiac output was measured. After this initial study, 10 patients were treated with verapamil (from 40 to 80 mg, three times daily) and 15 patients with nifedipine (long-acting form, from 40 to 80 mg daily). After one year, the hemodynamic study was repeated. Both drugs induced a reduction in blood pressure and in the total peripheral resistance without any reduction in the cardiac index. Verapamil reduced heart rate, particularly during exercise, but this effect was compensated by an increase in the stroke volume. The hemodynamic profile of these two calcium channel blockers clearly differs from the hemodynamic effects of beta blockers.
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