Low wall shear stress in carotid arteries in subjects with left ventricular hypertrophy.

Left ventricular hypertrophy (LVH) is an independent risk factor for cardiovascular complications including atherosclerosis. The close linkage between LVH and carotid atherosclerosis has been the focus of much research. However, the underlying mechanism linking the two conditions is not fully understood. Low wall shear stress contributes to intimal thickening and atherosclerosis development as a local mechanism. In the present study, we investigated the relationship between wall shear stress and LVH in subjects with risk factors for atherosclerosis. Eighty subjects with at least one risk factor for atherosclerosis; ie, hypertension, diabetes mellitus, hyperlipidemia, or smoking, were enrolled. Intimal-medial thickness (IMT), number of plaques, internal dimensions, and blood flow velocity in the common carotid artery were evaluated. Wall shear stress was calculated using a Poiseuillean parabolic model of velocity distribution: shear stress = 4 x blood viscosity x central flow velocity/internal dimension. Subjects were divided into two groups; LVH(-) (n = 36) and LVH(+) (n = 44), according to their left ventricular mass index (LVMI). Mean shear stress and systolic peak shear stress were significantly lower in subjects with LVH compared with subjects without LVH. Furthermore, mean shear stress (r = -0.42, P < .0001) and peak shear stress (r = -0.31, P < 0.01) were significantly inversely related to LVMI. Stepwise regression analysis revealed that wall shear stress independently correlated with LVMI as well as IMT. These results indicate that low shear stress could function as a local factor in the development of atherosclerosis in subjects with LVH.