Flow-induced vasodilation of the human brachial artery is impaired in patients <40 years of age with coronary artery disease

zThe objective of this study was to determine whether abnormal flow-induced endothelium-dependent vasodilation in the brachial artery identifies young patients with coronary artery disease (CAD). High-resolution ultrasonography was used to measure vascular reactivity in a peripheral conduit vessel, the brachial artery, in 14 young men with CAD and in 11 age-matched, healthy, merle volunteers, Endothelium-dependent vasodilation was determined by measuring the change in brachial artery diameter during increases in flow induced by reactive hyperemia. Endothelium-independent vasodilation was assessed by administration of sublingual nitroglycerin. To ascertain whether flow-mediated vasodilation in humans is mediated by endothelium-derived nitric oxide, brachial artery diameter was measured during reactive hyperemia, before and during administration of the nitric oxide synthase antagonist N-G-monomethyl-L-arginine (L-NMMA). Brachial artery diameter was also measured during intraarterial infusion of acetylcholine and nitroprusside before and after administration of L-NMMA. Flow-induced vasodilation was less in patients with CAD than in healthy volunteers (1.3+/-1.1% vs 6.2+/-0.7%, p <0.05). Nitroglycerin increased brachial artery diameter similarly in each subject group (11.3+/-1.0% vs 15.8+/-1.2%, p=NS). L-NMMA inhibited flow-mediated vasodilarion and the vasodilative response to acetylcholine, but did not affect the response to nitroprusside. It is concluded that abnormal flow-induced endothelium-dependent vasodilation occurs in the brachial artery of young patients with CAD. (C) 1996 by Excerpta Medica, Inc.