[Flow-dependent vasodilation of the brachial artery in the normotensive and essential hypertensive patient].

Brachial artery hemodynamics including brachial artery diameter (D), local blood flow velocity (V) and local volumic blood flow, was studied in 10 normotensive subjects (NT) and 10 age-matched hypertensive patients (HT) (50 +/- 4 vs 43 +/- 4 years; m +/- SEM; NS), using a bidimensional pulsed doppler system at rest (control period), during a 2 (or 4) mn-period of distal circulatory occlusion (DO) and during the following reactive hyperemia (RH). Kinetics of change in blood flow velocity and diameter were determined during successive and reproducible manoeuvres. V and D decreased significantly during DO. During RH (1) V reached similar maximum values in both groups (after 2 mn DO: NT: from 2.4 +/- 1.1 to 19.0 +/- 6.9 cm/s; HT: from 2.9 +/- 0.8 to 17.2 +/- 7.6 cm/s) and (2) D increased significantly in both groups (after 2 mn DO: NT: from 0.395 +/- 0.016 to 0.450 +/- 0.025 cm; p less than 0.001; HT: from 0.408 +/- 0.018 to 0.467 +/- 0.018 cm; p less than 0.001), reaching levels significantly higher than during the control period. The brachial artery vasodilation observed in both groups (NT: +12 +/- 3 p. 100; HT: +15 +/- 3 p. 100 of initial diameter) was significantly greater (p less than 0.001), than the reproducibility of the diameter measurement (3 +/- 1 p. 100). Mean arterial pressure and heart rate dit not change during the whole investigation. Increasing the duration of DO from 2 to 4 mn further enhanced the reactive blood flow velocity but did not change the magnitude of the reactive brachial artery vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)