IN-VIVO ASSOCIATION BETWEEN LOW WALL SHEAR-STRESS AND PLAQUE IN SUBJECTS WITH ASYMMETRICAL CAROTID ATHEROSCLEROSIS

Background and Purpose It is known that atherosclerosis does not invol ve both carotid arteries to the same extent. Pathological investigatio ns have demonstrated that lesions develop in regions of low wall shear stress. The aims of the present study were to verify the degree of ca rotid atherosclerosis asymmetry in a population-based study and to eva luate whether wall shear stress is lower in carotids with atherosclero tic lesions than in carotids without lesions. Methods Participants in a cardiovascular disease prevention campaign (n=1166) were screened fo r carotid atherosclerosis by echo-Doppler examination. Of these, 23 su bjects who pre -sented plaque in the common carotid or bulb of one sid e and no plaque in the contralateral carotid tree were enrolled for co mmon carotid wall shear stress measurement. Shear stress was calculate d according to the following formula: Shear Stress=Blood ViscosityxBlo od Velocity/Internal Diameter. Results Of the 1166 subjects screened, 400 (34%) had plaque and/or stenosis in the carotids. Ninety subjects had lesions exclusively in the right carotid, 111 had lesions exclusiv ely in the left, 70 had lesions in both carotids but with different de grees of severity, and only 129 had similar lesions in both carotids. In the 23 subjects in whom wall shear stress was measured, peak shear stress was 18.7+/-4.1 and 15.3+/-4.0 dynes.cm(-2) (mean+/-SD) (P<.0001 ) in the side without and the side with plaque, respectively. Mean she ar stress yielded similar results. Conclusions The present results dem onstrate that the atherosclerotic involvement of carotid arteries is u sually asymmetrical and that wall shear stress is lower in the carotid arteries where plaques are present than in plaque-free arteries. Thes e findings provide in vivo evidence for a strong association between s hear stress and atherosclerotic lesions.