家兔颈动脉粥样硬化壁面剪应力分布及作用的探讨

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

目的探讨家兔颈总动脉粥样硬化（As）发病过程中动脉血管壁上壁面剪应力（WSS）的分布及其对AS进程的影响。方法24只新西兰大白兔随机分为对照组（正常饲料喂养，12只）和实验组（采用空气干燥加高脂饮食制造AS模型，12只）。空气干燥术后2、4、8、12周采用彩色多普勒超声及血流剪应力定量分析软件测定血流动力学参数，分别于术后第4、8、12周处死实验组兔4只，处死前检测血脂，并做病理切片观察颈动脉病变的形态特征，对照组兔在第4周全部处死，获得相应的数据，进行对照分析。结果实验组的各项血脂指标呈不同程度的升高，与对照组比较差异具有统计学意义（P〈0．01）。实验组从实施手术开始至术后4周，颈总动脉低WSS数目的分布增加，实验组左侧颈总动脉内约45％的WSS集中在0．2～0．4N／m2，右侧约36％，左侧颈总动脉WSS降低的速度比右侧进展快。至术后8～12周，实验组颈总动脉低WSS分布反而减少，而高WSS血流点数目增加，实施干燥术后12周，实验组颈总动脉管壁逐渐僵硬、增厚，脂质沉积增加，平滑肌移行增殖，胶原增生，弹性降低，实验组左侧颈总动脉AS程度重于右侧。各项实验结果均证实实验组出现较典型的AS改变。结论随着AS进程的延长，实验兔颈总动脉局部wSS逐步降低，低WSS进一步刺激血管内皮细胞增生，出现颈总动脉内中膜增厚及血管重构，提示颈总动脉WSS减低与动脉AS的形成有关。

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,Sth, 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, statistically significant （ P d0.01）. In the 4th week,the and the difference between the two groups was 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.