The diameter, blood velocity, and blood flow of the brachial artery were evaluated with a pulsed-Doppler apparatus before and after wrist occlusion in 16 normocholesterolemic and 27 hypercholesterolemic male subjects of similar age and body mass index. Before occlusion, no hemodynamic differences were observed between the two groups. Occlusion significantly reduced blood velocity and blood flow in the two groups (p< 0.001), but such reductions were not different between hypercholesterolemic and

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... normocholesterolemic groups. Occlusion decreased the arterial diameter in the hypercholesterolemic group only (p<0.001), and absolute diameter changes after occlusion were significantly different between the two groups (p< 0.001). No correlation was found between the change in arterial diameter after occlusion and the baseline diameter before occlusion in the normocholesterolemic and hypercholesterolemic population overall. Absolute and percent diameter changes after occlusion were correlated with total cholesterol (r=-0.73, r= -0.72; p<0.001) and with low density lipoprotein (LDL) cholesterol (r=-0.68, r=-0.69;/><0.001) in the normocholesterolemic and hypercholesterolemic population overall, respectively. These findings indicate that the low-flow state induces a reduction in large-artery diameter in the hypercholesterolemic but not in the normocholesterolemic state and is closely related to the degree of elevation of blood cholesterol and of its LDL fraction. (Arteriosclerosis and Thrombosis 1991;11:161-166)