Association between risk factors for atherosclerosis and mechanical forces in carotid artery.

BACKGROUND AND PURPOSE Mechanical stresses on the arterial wall participate in the pathogenesis of atherosclerosis as local factors. The relationships between local mechanical forces and risk factors for atherosclerosis were investigated. METHODS Mechanical forces on the arterial wall were evaluated in the carotid artery in 117 patients with risk factors for atherosclerosis including hypertension, dyslipidemia, diabetes mellitus, and smoking, as well as in 20 age- and sex-matched normal controls. Circumferential wall tension and shear stress were evaluated with Laplace's law and a poiseuillean parabolic model of velocity distribution. Circumferential wall strain was also evaluated as carotid mechanical force. RESULTS Mechanical forces in subjects with risk factors were characterized by low wall shear stress, high circumferential wall tension, and reduced strain. Systolic blood pressure was significantly negatively associated with shear stress and circumferential wall strain. HDL cholesterol showed a significant positive correlation with shear stress and a negative correlation with wall tension. Fasting blood glucose was significantly associated with shear stress, while smoking showed a negative correlation with shear stress and a positive correlation with wall tension. Accumulation of risk factors was associated with further deterioration of mechanical forces. Furthermore, stepwise regression analysis showed that the number of risk factors was significantly associated with mechanical forces independently of carotid intima-media thickness. CONCLUSIONS These findings suggest that risk factors for atherosclerosis were associated with alteration of mechanical forces. Consequent alteration in mechanical forces could be an underlying local mechanism for the progression of atherosclerosis.