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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: To study the hemodynamic causes of atherosclerosis by analyzing the effect of blood flow in the blood vessels on blood vessels and the behavior of low density lipoprotein (sLDL) particles in the blood. Methods: In the first step, a CFD model of arterial vascular bifurcation was established using the CFD software. In the second step, the blood flow characteristics were analyzed and the sLDL particles in the blood range of 15-25 nm were tracked in the arterial bifurcation model The hydrodynamic behavior of sLDL was studied in the blood vessels in the stable blood flow velocity and the distribution of the flow field characteristics. Results: There was a high pressure area in the beginning of blood vessel. Blood flows slowly outside the branches at the medial and bifurcations of the arterial vessels, and areas of higher pressure appear at these sites. At the lateral and branch points of vascular flexion, the sLDL collides with the vascular wall is more likely to collide with other sites, and the particles are distributed in a patchy manner in these areas where the vascular deposition is high. DISCUSSION AND CONCLUSION: The high pressure at the beginning of the blood vessel may be the main reason leading to this part of vascular injury, which in turn leads to the formation of atherosclerosis. The distribution of high pressure and low velocity blood flow at the lateral and bifurcation points of arterial vessels, Increases the contact time of blood-borne pathogenic factors, including sLDL particles, with the vessel wall, and on the other hand increases the leakage of serum at these sites, with the so-called ’concentration polarization’ resulting in these sites The distribution of sLDL with high concentration increased the contact probability of sLDL particles with the vessel wall. Particles with high incidence of deposition on the blood vessels often existed at the bifurcation point of arterial vessels, The role of shear pressure in long-term mild vibration changes the properties of most vascular endothelial cells and promotes the formation of arteriosclerosis. The low velocity distribution of blood, the high deposition rate of sLDL particles and the low shear stress are the important factors in the development and evolution of atherosclerosis at the beginning of arterial blood vessels, at the bending and at the bifurcation point.