Forearm Resistance-Vessel Dilatation Function During Reactive Hyperemia in Patients With Resistant Hypertension

Forearm blood flow (FBF) measured during reactive hyperemia by venous-occlusion plethysmography assesses resistance-vessel dilatation function but has never been investigated in resistant hypertension. The aim was to evaluate the independent correlates of forearm resistance-vessel function parameters in resistant hypertensives.

In a cross-sectional study, 274 resistant hypertensives performed 24-hour ambulatory blood pressure (BP) monitoring, 2D-echocardiography, aortic pulse wave velocity, and venous-occlusion plethysmography with baseline and hyperemic FBF and vascular resistance measurements. A subsample of 103 patients also performed ultrasonographic brachial artery endothelial function examination. Independent correlates of baseline and hyperemic vascular parameters were assessed by multiple linear regressions.

Median (interquartile range) baseline FBF was 3.1 (2.4-4.0) ml/min/100ml of tissue, and during hyperemia mean FBF rose to 7.0 (5.2-9.4) ml/min/100ml of tissue. Baseline FBF and resistance were independently associated with left ventricular mass index (partial correlations -0.14 and 0.13, respectively), whereas hyperemic parameters were independently associated with body mass index (BMI) (inversely for FBF, partial correlation: -0.18 to -0.21) and with the nocturnal BP fall (directly for FBF, partial correlation: 0.12-0.15), after adjustments for age, sex, mean arterial pressure, and baseline vascular parameters. In a separate analysis, a larger brachial artery diameter was associated with higher hyperemic FBF, but there were no associations between resistance-vessel and conduit-vessel dilatation function parameters.

In patients with resistant hypertension, left ventricular mass was the only correlate of baseline FBF and resistance, whereas higher BMI and lower nocturnal BP fall were independently associated with lower FBF and higher resistance during reactive hyperemia.