[Effects of nifedipine on carotid blood flow and baroreflex response in essential arterial hypertension. Preliminary results].

The objective of this prospective study was to evaluate the effect of nifedipine administered at usual daily doses of 30 to 40 mg on the carotid flow in arterial hypertension. The study included 15 patients (8 men and 7 women), 50 to 79 (mean 59.5) years old suffering from long-standing, fixed essential hypertension becoming instable under central antihypertensive drug therapy. For calculating the carotid blood flow, vascular echotomography combined with Doppler ultrasonography and spectral analysis (Duplex probe) determining the vascular section and flow velocity were used. Arterial pressure using a mercury tonometer, flow velocity, common carotid artery diameter, carotid blood flow, Pourcelot's index, parietal tension and heart rate were measured before treatment and at the 8th day of nifedipine administration. It could be shown that the drug produced a significantly (p less than 0.001) increased carotid blood flow, in spite of a marked (p less than 0.001) decrease in systolic (p less than 0.001) and diastolic (p less than 0.005) blood pressure. The increase in carotid blood flow was directly related to the increase in flow velocity (p less than 0.001) and in the diameter of common carotid artery (p less than 0.01) and was associated with a significant decrease in the Pourcelot's index. Analysis of two groups of patients isolated from the total group according to the elevation of carotid blood flow, showed that the degree of hypotensive effect of nifedipine is negatively correlated with the baroreflex response determined by the variation of parietal tension.(ABSTRACT TRUNCATED AT 250 WORDS)