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

The aim of our study was to evaluate the effect of antihypertensive treatme nt on flow-mediated dilation (FMD)of a large artery, a noninvasive estimate of endothelial function, in hypertensive patients. In 78 consecutive hyper tensive 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 mu g); br achial 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 antihy pertensive drugs; in a second study, the FMD was assessed in 20 patients af ter 2 months of monotherapy with either nifedipine or hydrochlorothiazide. In the first study, FMD was significantly increased after treatment compare d 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 pressu re 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 treat ment (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 pat ients receiving hydrochlorothiazide (from 5.15+/-5.28% at baseline to 4.69/-4.34%, NS). No significant changes of endothelium-independent dilation we re 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, res pectively, NS). Thus, in essential hypertensive patients an improvement of the impaired FMD of the brachial artery, evaluated by noninvasive ultrasoun d, may be observed after long-term, effective blood pressure reduction, sug gesting a beneficial effect of antihypertensive treatment on endothelial fu nction. It seems that beyond blood pressure control, a calcium antagonist m ay be more effective than a diuretic in this respect.