The effect of acute and chronic nicardipine therapy on forearm arterial haemodynamics in essential hypertension.

By using simultaneous recording curves obtained with pulsed Doppler velocimetry and strain gauge mechanography, forearm arterial haemodynamics were studied in 26 patients with mild to moderate essential hypertension. Fifteen patients received a single oral dose of nicardipine 40 mg, and 11 patients were treated with nicardipine 30 mg three times daily for 3 months. In both groups of patients there was a similar and significant (P less than 0.001) reduction in mean, systolic, and diastolic pressures. There was a slight increase in heart rate (P less than 0.05) after the single dose, but no change after 3 months of treatment. The diameter, blood velocity, and blood flow of the brachial artery increased significantly in both treatment groups. The decrease in forearm vascular resistance was significant for both treatment groups. Brachial artery compliance increased (P less than 0.01) and characteristic impedance decreased (P less than 0.01) after both single-dose and long-term therapy with nicardipine. In patients who received nicardipine for 3 months, there were close correlations between the baseline serum calcium level and the percent change in vascular resistance (r = -0.73, P less than 0.01), blood flow (r = 0.89, P less than 0.001), and blood velocity (r = 0.91. P less than 0.001) of the forearm. No correlation was found between the baseline serum calcium and the change in arterial pressure. This study provided evidence that the blood-pressure-lowering effect of nicardipine was accompanied by a direct vasodilatory action in the small and large arteries of the forearm. An increase in peripheral blood flow with concomitant improvement of arterial compliance are the consequences of these arterial actions.