Human common carotid wall shear stress as a function of age and gender: a 12-year follow-up study

Abstract

Hemodynamic forces play a role in the development of atherosclerosis. Their variations with age have been assessed in cross-sectional, but not longitudinal, studies. The aim of the present study was to investigate in both sexes the age-dependent change in wall shear stress and arterial stiffness in subjects studied twice 12 years apart. Forty-eight subjects (15 women and 33 men) were studied twice 12 years apart. Subjects underwent blood viscosity measurement and echo-Doppler of carotid arteries, from which the intima-media thickness (IMT) was measured and the wall shear stress and Peterson's elastic modulus were calculated. Blood viscosity increased in both sexes, more markedly in women (+13.2%) than men (+7.2%). Common carotid diameter increased in both sexes, but in men (+7.4%) more than in women (+5.5%). Peak and mean velocity decreased at follow-up by 10.7% and 18.9% in women and by 14.2% and 18.1% in men. Peak and mean shear stress significantly decreased in men by 13.0% and 17.5%, respectively, while in women only the mean shear stress was reduced (−11.8%). The IMT of the common carotid artery increased by 29% in women and 20% in men. Arterial stiffness significantly increased (+74.5% in women and +28.0% in men). The percent change in mean shear stress was significantly and inversely associated with the percent change in IMT. The data of this study show that, in a middle-aged population observed for almost 12 years, the mean shear stress decreases significantly in both sexes, while peak shear stress decreases significantly only in men. The change in mean shear stress is inversely associated with changes in IMT. Arterial stiffness, on the other hand, increases with aging.

Carotid endothelial shear stress reduction with aging is associated with plaque development in twelve years

“…In addition, the present results expand our previous prospective data on the relationship between shear stress and intima-media thickness in the same population [16]; in the present data, established carotid atherosclerosis has been considered; tensile forces have been taken into account, and the asymmetric atherosclerosis model has ruled out many possible confounding factors.…”

“…The reproducibility of the measurements has been previously reported, including in terms of coefficients of variations [4,16]. In summary, the haemodynamic data of 36 subjects who participated in the baseline examination were compared to 36 new subjects matched for age, sex and cardiovascular risk factors: no significant differences were detected regarding blood viscosity and velocity, arterial diameter, and shear stress.…”

“…Twelve years later, the same population was recalled in order to repeat the examinations, which showed that shear stress had decreased significantly. This age-related change was independently associated with increases in local intima-media thickness, an early atherosclerosis marker [16].…”

“…Details of follow-up analysis after 11.6 years, in terms of the studied population and applied methods have been reported elsewhere [16].…”

Impact of Age and Aerobic Exercise Training on Conduit Artery Wall Thickness: Role of the Shear Pattern

“…In vitro studies have demonstrated that unidirectional high shear stress induces the expression of antiatherogenic genes (i.e., endothelial nitric oxide synthase and superoxide dismutase) and inhibits the expression of atherogenic genes (i.e., vascular cell adhesion molecule, intercellular adhesion molecule, and endothelin-1), whereas retrograde shear and/or low mean shear promote a proatherogenic phenotype [24]. A previous follow-up study reported that decreases in mean carotid artery shear stress correlated with increases in carotid artery IMT [25]. In peripheral conduit arteries, acute and chronic increases in antegrade shear have beneficial effects on arterial function [12,13,26], whereas acute and chronic increases in retrograde shear are associated with endothelial dysfunction [14,15,27].…”