RESUMEN
Objective To analyze the change of the shear stress in atherosclerotic carotid artery of rabbits and its effect on the plaque and intimia-media pathological morphology. Methods Totally 36 male Japanese White rabbits were randomly divided into blank control group (n=6), sham operation control group (n=6) and the surgery group (n=24). The blank control group was fed by normal diet. The sham operation control group was fed by the high-cholesterol diet. The surgery group was fed by high-cholesterol diet and treated by air-drying. In the 2nd, 4th, 8th and 12th week after operation, the hemodynamic parameters were measured using Color Doppler Flow Imaging. Blood viscosity was determined and the degree of artery stenosis was showed by digital subtraction angiography (DSA). The stenosis rate, mean shear stress, intimia-media ratio and mean integrated optical densities (IOD) of media smooth muscle cells (SMC) were calculated respectively. Results The typical atherosclerotic plaque was presented in surgery group. The thickness of media and mean IOD of SMC were increased at the 2nd week after operation. However, following the increase of the stenosis rate and shear stress, the flow field was changed on the stenotic artery. The pathological morphology showed the character of vulnerable plaque such a large lipid core, thin fibrous cap, and plaque rupture at 4th, 8th week after operation. The media showed atrophy and became thin, mean IOD of SMC was decreased. Statistic analysis showed significant difference in the 2 week group compared with other group. Conclusion Following the increase in the degree of stenosis, the flow shear stress is increased, turbulent flow presents, and flow field changes on the stenotic artery. Thus the plaque become unstable , and the vessel occurs remodeling.