Hemorheologic effects of vasodilation in essential hypertension.

Arterial hypertension is often associated with plasma volume contraction and hemocon centration, which negatively affect the vascular flow resistance and microcirculation. Since some antihypertensive drugs can affect blood rheology, the purpose of this study was to evaluate whether acute and long-term arterial vasodilation with cadralazine influ ences rheologic parameters in essential hypertension. Twelve patients with unsatisfacto rily controlled essential hypertension were studied. In the acute double-blind phase of the study the patients were allocated to treatment with either cadralazine or placebo. Intraarterial blood pressure, cardiac output (dye dilution), and blood rheology (viscosity, hematocrit) were registered before and after the first dose of cadralazine. Then 9 patients (3 dropouts) were treated with cadralazine and placebo during two four-week crossover periods and continued with cadralazine medication during the eight-week open phase of the study. Blood pressure and blood hemoglobin were f...