Enhanced constriction of the peripheral large artery in response to acute induction of a low-flow state in human hypercholesterolemia.

Abstract

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 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) H ypercholesterolemia is recognized as a major cardiovascular risk factor, 1 but the determination of its dominant hemodynamic changes associated with early lesion development remains unclear.2 Recent observations of aortas isolated from animals fed cholesterol-rich diets have shown several alterations in vascular reactivity, such as an augmented contractile responsiveness to certain vasoactive substances.3 These alterations were reversible with a switch to cholesterol-poor diets, 4 and it has been speculated that changes in endothelial function might play an important role in their mechanisms. 5 The objective of our study was to investigate in vivo the influence of hypercholesterolemia on large-artery reactivity in humans. The bra-

Low-Flow Mediated Constriction is Endothelium-Dependent

“…There is some evidence that impaired vascular function in the radial artery is associated with diminished L-FMC responses, 1,3 whereas brachial artery L-FMC may be increased in subjects with risk factors or coronary disease. 5,21,22 Our findings are in broad agreement with previous studies of the radial artery, 1,3 but contrast with those in the brachial artery, reinforcing a previous suggestion of arterial site specificity in vasoconstrictor function. 4 Furthermore, the impact of coronary catheterization on systemic conduit artery This study had a number of limitations.…”

Does lowering of cholesterol levels influence functional properties of large arteries?

“…However, in this group of patients mean total cholesterol and LDL levels were rather high and the study population also contained patients with cardiovascular complications, including hypertension. Data in the literature have shown that, in the brachial artery, diameter and blood flow were no different in normocholesterolaemic subjects than in patients with hypercholesterolaemia, although the arterial diameters tended to be somewhat larger in the hypercholesterolaemic group [34]. In the latter study it was suggested that cholesterol probably does not influence the arterial circulation under basal conditions, but might be still able to alter large artery reactivity.…”

Vessel Wall Properties of Large Arteries in Uncomplicated IDDM

“…Arterial diameters of the CCA and FA were slightly larger in IDDM patients. During the early stages of atherosclerotic disease, arterial diameter may indeed become increased (33,34). Since the CCA and FA, in contrast to the BA, are most prone to atherosclerosis in diabetic patients, the presence of early (still below the detection limit of B-mode scanning) atherosclerosis cannot be excluded.…”