Effect of treatment on flow-dependent vasodilation of the brachial artery in essential hypertension

Abstract

The aim of our study was to evaluate the effect of antihypertensive treatment on flow-mediated dilation (FMD)of a large artery, a noninvasive estimate of endothelial function, in hypertensive patients. In 78 consecutive hypertensive patients (40%men; age range, 42 to 67 years) we measured by a high-resolution ultrasound system the changes of brachial artery diameter during reactive hyperemia and after sublingual glyceryl trinitrate (400 μg); brachial artery flow velocity was measured by pulsed Doppler. The results of 2 studies are reported. In the first study, this procedure was repeated in 58 patients after 6 and 12 months of treatment with a combination of antihypertensive drugs; in a second study, the FMD was assessed in 20 patients after 2 months of monotherapy with either nifedipine or hydrochlorothiazide. In the first study, FMD was significantly increased after treatment compared with baseline (from 3.1±3% at baseline to 6.5±4.5% at 6 months and to 8.12±4.6% at 12 months; P<0.001 by ANOVA), concomitant with blood pressure reduction (from 162±24/102±13 mm Hg to 141±12/89±6 mm Hg and to 141±9/89±6 mm Hg; P<0.001 by ANOVA); significant changes of endothelium-independent dilation were also observed, but only after 12 months of treatment (from 14.2±4.8 at baseline to 15.5±4.7 at 6 months and 16.8±5.9% at 12 months; P=0.03 by ANOVA). In the second study, FMD was significantly increased during nifedipine treatment as compared with baseline (from 5±6.18% at baseline to 9.45±3.94%, P<0.001), while it did not change in patients receiving hydrochlorothiazide (from 5.15±5.28% at baseline to 4.69±4.34%, NS). No significant changes of endothelium-independent dilation were observed with both drugs (from 17.10±2.4% to 18.14±3.76% and from 18.73±4.07% to 17.46±4.27% during nifedipine and hydrochlorothiazide, respectively, NS). Thus, in essential hypertensive patients an improvement of the impaired FMD of the brachial artery, evaluated by noninvasive ultrasound, may be observed after long-term, effective blood pressure reduction, suggesting a beneficial effect of antihypertensive treatment on endothelial function. It seems that beyond blood pressure control, a calcium antagonist may be more effective than a diuretic in this respect.