多重力学刺激作用下新内膜重塑模型构建和数值模拟研究

Construction and numerical simulation of neointimal remodeling model under multiple mechanical stimulation

目的支架植入造成血管内膜损伤引起新内膜重塑。本文旨在构建支架植入后力学刺激新内膜重塑模型,探讨支架植入后动脉应力和壁面切应力对新内膜重塑的影响及新内膜重塑过程中的血管应力分布。方法建立支架植入模型、支架段血流模型,计算支架植入后血管壁力学刺激;通过促生长因子g描述力学刺激与细胞增殖的关系,并构建细胞增殖迁移模型,模拟细胞聚集形成新内膜过程。模拟动脉应力、壁面切应力单独作用下新内膜重塑,以探讨两种力学刺激作用效果的差异;模拟动脉应力和壁面切应力共同作用下新内膜重塑过程,得到重塑过程血管应力分布的变化。结果在动脉应力作用下,新内膜集中在支架段,对支架段管腔影响更大;在壁面切应力作用下新内膜重塑范围更广,除支架段还包括上、下游。新内膜重塑会使血管壁应力峰值和高应力区域减小,重塑后血管壁应力峰值由0.277 MPa下降至0.098 MPa,高应力区域体积减少了64.6%。结论新内膜重塑模型可得到支架植入后血管形貌和应力的动态变化。不同力学刺激作用下,新内膜位置与重塑速度有显著性差异,具有不同特征。新内膜可对血管壁起到一定程度的支撑作用,使血管壁的高应力区域明显减少。

Objective The implantation of stents causes endothelial injury in blood vessels,leading to neointimal remodeling.This article aims to construct a model of neointimal remodeling under mechanical stimulation after stent implantation,explore the effects of arterial stress and wall shear stress on neointimal remodeling,and investigate the distribution of vascular stress during the neointimal remodeling process.Methods A stent implantation model and a blood flow model in the stent segment were established to calculate the mechanical stimulation on the vessel wall after stent implantation.The relationship between mechanical stimulation and cell proliferation was described by growth factor g,and a cell proliferation and migration model was constructed to simulate the process of cell aggregation forming the neointima.The neointimal remodeling process was simulated separately under arterial stress and wall shear stress to explore the differences in the effects of the two mechanical stimulations.The changes in vascular stress distribution during the neointimal remodeling process under the combined effects of arterial stress and wall shear stress were also obtained.Results Under arterial stress,the neointima was concentrated in the stent segment,with a greater impact on the lumen of the stent segment.Under wall shear stress,the neointimal remodeling range was wider,including both upstream and downstream of the stent segment.Neointimal remodeling reduced the peak and high-stress areas of vascular wall stress,with the peak stress value decreasing from 0.277 MPa to 0.098 MPa,and the volume of high-stress areas decreasing by 64.6%after remodeling.Conclusions The neointimal remodeling model can capture the dynamic changes in vascular morphology and stress after stent implantation.Different mechanical stimulations lead to significant differences in the neointima location and remodeling speed,with distinct features.The neointima can provide a certain degree of support to the vascular wall,leading to a significant reduction in high-stress areas of the vascular wall.