动脉硬化仿真模拟分析

The Simulation Analysis of Atherosclerosis

目的:通过对血管中血液流动对血管的影响及血液内低密度脂蛋白(sLDL)微粒行为的模拟分析,研究动脉粥样硬化产生的血流动力学原因。方法:第一步,使用流体力学软件CFD,建立动脉血管弯曲分叉仿真模型;第二步,分析血液流动特性,跟踪血液中15-25纳米尺度范围类的sLDL粒子在动脉分叉模型中的流体力学行为,研究sLDL在血液流速稳定下在血管中的空间分布及流场特征分布。结果:血管起始段出现压强很高的区域。在动脉血管弯曲内侧处及分岔处的分支外侧血液流动较慢,并且在这些部位出现压强较高的区域。在血管弯曲外侧处及分岔点处,sLDL与血管壁发生碰撞的几率较其它位置较高,粒子在血管上沉积高发区域在这些部位呈斑块状分布。讨论及结论:在血管起始段的高压,可能是导致这一部分血管损伤,并进而引起动脉硬化形成的主要原因;在动脉血管弯曲外侧处及分岔点处出现的高压低速血流分布,一方面增大了血液中包括sLDL粒子在内的致病因子与血管壁的接触时间,另一方面则引起这些部位血清的侧漏加强,出现所谓的'浓度极化'现象,从而导致这些部位出现高浓度的sLDL分布,增大sLDL粒子与血管壁的接触几率;粒子在血管上沉积高发区域往往存在于动脉血管分岔点处,而在血管弯曲外侧处也有较高几率沉淀,呈斑状分布;长期性轻微性振动的剪切压力的作用使多数血管内皮细胞性质改变,促进动脉硬化形成。在动脉血管起始段、弯曲处及分岔点处血液的高压低速分布、sLDL粒子的高沉积率及低剪切应力等是动脉硬化产生及演化的重要因素。

Objective： In this work, the blood flow and the behavior of small dense low density lipoprotein （sLDL） in artery were simulated, and the blood hydrodynamics mechanism in the generation of atherosclerosis was analyzed subsequently. Methods： The emulational blood vessel crotched model was built using hydrokinetics soft-ware, the blood inflow was selected as steady flow and it was analyzed. And the behavior of sLDL particles in 15-25 nanometer range was simulated. The space distributing, the pressure of blood on vessel and the flow field of sLDL, and etc. were studied in this paper. Results： The result shows： a） The blood flow nearby the crook of vessel and the crotched vessel were slower than others position; b） There were some high pressure regions nearby the start and the crook of vessel and the crotched vessel; c） The particles deposited usually nearby the crook of vessel and the crotched vessel. Conclusions： The high pressure nearby the crook of vessel and the crotched vessel would accelerate the leak of the blood serum from these regions, and the blood flows in these areas were slow. These would induce high density of sLDL in these areas, this was recognized as the important causation for the damnification of vessel endoderm. The high pressure nearby the start of vessel may be the main cause of atherosclerosis in this area. The sLDL particles always hit the vessel nearby the crook and the crotched areas, this would increase the contact probability between the sLDL and the vessel endoderm, and there would be long-standing shearing strength which may change the property of endothelial cell and induce the atherosclerosis. We could draw the conclusion that the high pressure, slow blood flow and high deposit probability nearby the crook of vessel and the crotched vessel play an important role in the generation of atherosclerosis, in which the sLDL is the main causation.