冠脉支架虚拟植入过程的流固耦合动力学模型

A Dynamic Fluid-solid Interaction Model for Virtual Implantation of Coronary Stents

考虑了弯曲冠脉和血管支架的变形对腔内血流动力学特性的影响,构建了扩张冠脉-剪切细化血液流体的顺序流固耦合动力学模型。研究了血管支架连接筋几何结构(S型和N型)和血管狭窄率(24%、40%、50%)对血流动力学特性的影响,分析了血管支架介入引起的血管等效应力和血流脉动作用下的壁面剪切应力,进而评价了血管斑块的生物力学损伤。数值结果表明,血管斑块的高等效应力位于与血管支架连接筋接触的血管内最狭窄区域,血管斑块的高壁面剪切应力位于斑块组织径向下垂最显著区域。随着血管狭窄率的增加,血管斑块的等效应力和时间平均的壁面剪切应力显著上升,血管斑块面临的脆性断裂风险增强。与N型血管支架相比,S型血管支架具有更高的峰值壁面等效应力和壁面剪切应力,易于引起血管斑块壁面的脆性断裂。综上,所建立的冠脉支架虚拟植入过程的流固耦合动力学模型,对于评价血管损伤进而优化血管支架设计具有重要理论意义。

A sequential fluid-solid interaction model of expanded coronary-shear thinning blood is developed accounting for effect of both stent and vessel deformation on haemodynamics.The proposed computational model is employed to investigate the influence of stent link with different geometrical configurations(S-,N-shape)and vascular stenosis rates(24%,40%,50%)on haemodynamics.Both induced equivalent stress during stent implantation and wall shear stress by pulsating blood flow are obtained for biomechanical injury assessment within atherosclerosis plaque.The numerical results indicate that the developed high equivalent stress is located at the interface between the narrowest vascular lumen and stent link while high wall shear stress on the plaque with maximal radical tissue prolapse.With increasing vascular stenosis rates,the experienced equivalent stress and time-averaged wall shear stress remarkably increase leading to higher risk of plaque rupture.Compared with N-type stent,higher peak equivalent stress and wall shear stress are observed on the plaque for S-type stent implying a more vulnerable plaque prone to rupture.Consequently the developed fluid-interaction model will provide a theoretical significance for assessment of vascular injure and optimal design of coronary stent.