Study of the role and distribution of wall shear stress in rabbit atherosclerotic carotid artery

Abstract

Objective To dynamically observe the distribution of wall shear stress (WSS) in the carotid artery of rabbit and its impact on atherosclerosis(AS) by using AS model.Methods Twenty-four New Zealand white rabbits were randomly divided into control group (normal diet,n =12) and experimental group (air-drying plus high fat diet,n =12).In the 2nd,4th,8th,12th week after operation,hemodynamic parameters were measured by using color Doppler flow imaging and shear stress quantitative analysis software.Four rabbits in the experimental group were sacrificed at various times (from 4th to 12th week).And all animals of the control group were sacrificed in the 4th week.Serum lipids,pathology and other data were obtained,and morphological characteristics results were analyzed.Results Serum lipids in the experimental group increased to varying degrees,and the difference between the two groups was statistically significant (P ＜0.01).In the 4th week,the number of low WSS distribution in common carotid artery of the experimental group increased.WSS in left common carotid arteries concentrated in 0.2-0.4 N/m2 was approximately 45％,and 36％ in the right common carotid arteries.The reduced speed of WSS in left carotid arteries was much faster than in right carotid arteries.However,the number of low WSS distribution in common carotid artery of experimental group rabbits decreased in the 8-12 weeks,and the number of high WSS increased.Until the 12 weeks after surgery,carotid arterial wall in the experimental group became stiffer and thickening.The changes included proliferation of smooth muscle,formation of connective tissue matrix comprising elastic and collagen,accumulation of lipid and cholesterol in associated cells in the carotid artery of the experimental group.The degree of atherosclerotic disease in the left carotid artery of experimental group was heavier than that in the right.Experimental results had confirmed that the typical atherosclerotic plaque was presented in the experimental group.Conclusions Reduced WSS in local common carotid artery was found during the progress of AS.The low WSS stimulated vascular endothelial cells with carotid artery intima-media thickening and vascular remodeling.Reduced WSS in the vessel was associated with the development of atherosclerosis. Key words: Ultrasonography; Carotid artery; Atherosclerosis; Wall shear stress