球囊扩张式血管支架介入对弯曲血管的生物力学损伤研究

构建了球囊扩张式血管支架介入系统的非线性有限元模型,考虑了血管斑块类型对其本构模型的影响,分析了A型与B型血管支架在血管狭窄率-24%、40%、50%,曲率半径-6 mm、10 mm、20 mm,狭窄血管的壁面应力分布规律,研究了血管支架构型、狭窄血管几何参数和血管生物力学损伤的关系。数值分析结果表明,血管壁面应力随着狭窄率的增加而显著升高,随着血管曲率半径的增加而下降相对平缓;但是,扩张加载阶段的血管壁面应力显著高于卸载阶段,易于引起血管斑块的脆性断裂引起血管生物力学损伤。由于A型血管支架相对于B型血管支架具有纵向柔顺性更优的联接筋构型,导致A型血管支架引起的血管壁面应力低于B型支架,因而降低了A型血管支架对于血管的生物力学损伤。

NUMERICAL INVESTIGATION OF BIOMECHANICAL INJURE OF CURVED VESSELS INDUCED BY INTERVENED BALLOON EXPANDABLE VASCULAR STENT

The schematic nonlinear finite element model of intervened vascular stent is developed to investigate the relationship between stent design,arterial geometry and injures induced by implantation of a balloon expandable vascular stent into a stenosed artery.The influence of plaque composition in its constitutive model is also considered.The arterial wall stress distribution and magnitude are obtained and analyzed during A-stent and B-stent intervened to a curved vessel with varying restenosis rate of-24%,40%and 50%,and curvature radius of-6 mm,10 mm and 20 mm.The numerical results show that the arterial wall stress remarkably increases with increasing restenosis rate,while it decreases slowly with increasing curvature radius of the curved vessel.However,the arterial wall stress is much higher during expanding the stent than that during unloading the stent.Consequently,the resulting high arterial wall stress during expanding the stent can lead to plaque or arterial rupture and subject them to biomechanical injure.In addition,the stresses induced within plaque tissues and arteries by A-stent implantation is less than those by B-stent implantation because the former equipped with more flexible links exhibits larger longitudinal flexibility than the latter.These findings suggest a lower risk of arterial biomechanical injury for A-stent as compared with B-stent.