Comparison of endothelial function evaluated by strain gauge plethysmography and brachial artery ultrasound

Strain gauge plethysmography and brachial artery ultrasound are widely used to study endothelial function. No data on correlation between these two pr ocedures are reported. The present study compared these two methods and inv estigated the correlation between vasodilation and brachial wall shear stre ss. In six healthy subjects and ten patients with hypertension or obesity, strain gauge plethysmography was performed in resting conditions and after infusion of 7.5, 15 and 30 mug/min of acetylcholine, and brachial artery ul trasound in resting conditions and after 5 min hand ischemia. Wall shear st ress was calculated as: blood viscosity x blood velocity/internal diameter. Forearm blood flow following acetylcholine infusion increased more in heal thy subjects than in patients with hypertension or obesity. In addition, br achial artery dilated more in the former group. Change in brachial artery d iameter correlated with change in forearm blood flow, calculated as area un der the curve of acetylcholine infusion (r = 0.739, P < 0.001). Wall shear stress was higher in healthy subjects (67.8 +/- 20.0 dynes/cm(2)) than in p atients with either hypertension or obesity (39.2 +/- 16.7, P < 0.001), and correlated with variations of diameter (r = 0.796, P < 0.0002), and margin ally of blood flow (r = 0.516, P < 0.05). The present findings demonstrate that there is a high correlation between endothelial function evaluated by strain gauge plethysmography and brachial artery ultrasound. Wall shear str ess correlates with brachial artery diameter change following hand ischemia , and marginally with blood flow change following acetylcholine infusion. ( C) 2001 Elsevier Science Ireland Ltd. All rights reserved.