Low wall shear stress contributes to atherosclerosis of the carotid artery in hypertensive patients.

Numerous in vitro studies have indicated that low shear stress may contribute to intimal thickening and development of atherosclerosis. In the present study, we investigated wall shear stress in hypertensive patients and its relevance to atherosclerosis in the carotid arteries by means of a non-invasive technique. Fifty-five hypertensive patients and 23 normotensive controls were investigated. Intima-media thickness, number of plaques, internal dimension and blood flow velocity of the carotid artery were evaluated. Wall shear stress was calculated using the Poiseuillean parabolic model of velocity distribution as follows: shear stress = 4 X blood viscosity X central line flow velocity/internal dimension. Hypertensive patients showed increased intima-media thickness and dilated common carotid arterial dimension relative to normotensive controls. There was no difference in blood viscosity between the two groups. Both the mean shear stress and systolic peak shear stress were significantly lower in hypertensive patients than normotensive controls. Further, wall shear stress at both mean and peak velocity was significantly and negatively related to intima-media thickness and number of plaques in hypertensive patients, as well as in the total study population. These findings indicate that structural and functional alterations in the common carotid artery of hypertensive patients further precipitates atherosclerosis through low shear stress.