冠脉可降解支架介入的血管力学特性数值模拟与实验研究

Numerical Simulation and Experimental Study on Vascular Mechanical Properties of Coronary Degradable Stent Intervention

目的探究可降解支架在动态降解过程中,血管应力变化对内皮功能恢复以及血管再狭窄抑制作用的影响。方法拟合超弹性血管本构关系的材料参数,通过数值模拟计算支架介入前以及动态降解过程中血管内膜应力分布;采用体外培养实验,设置硅胶腔体拉伸率分别为0%、5%、10%、15%,模拟不同降解阶段的力学环境,探究不同拉伸率下对内皮细胞生长状态的影响。结果支架完全降解后,血管内膜周向应力、应变恢复到0.137 MPa、5.5%,与支架介入前生理参数(0.122 MPa、4.8%)接近;体外实验表明,在0.1 MPa周向应力、5%应变条件下,内皮细胞成活率最高,能实现全部黏附生长。结论支架随降解进程的发生,内膜周向应力、应变恢复到接近生理参数范围,促进内皮细胞的生长,完整内皮功能的维持有效抑制了血管再狭窄进程。结果可为研究冠脉介入治疗血管再狭窄问题提供理论依据和实验平台。

Objective To explore the effect of vascular stress changes on endothelial function recovery and vascular restenosis inhibition in dynamic degradation process of the degradable stent. Methods The material parameters of the hyper-elastic vascular constitutive relationship was fitted,and the stress distribution on the intima of the blood vessel before stent implantation and during dynamic degradation was calculated by numerical simulation. In vitro culture experiments were carried out,and the stretch ratios of the silicon chambers were 0%,5%,10% and 15%,respectively,to simulate the mechanical environment at different degradation stages,and to explore the effects of different stretch ratios on growth state of the endothelial cells( ECs). Results After the stent was completely degraded,the circumferential intimal stress and strain of the vessel were restored to0. 137 MPa and 5. 5%,which were close to the physiological parameters( 0. 122 MPa,4. 8%) before stent implantation. In vitro experiments showed that the survival rate of ECs was the highest under the condition of0. 1 MPa circumferential stress and 5% strain,and adhesion growth could be achieved. Conclusions With the occurrence of stent degradation process,the circumferential stress and strain of the intima were restored to a range close to physiological parameters,which promoted the growth of ECs. The recovery of intimal function could effectively inhibit the process of vascular restenosis. The results can provide the theoretical basis and experimental platform for studying coronary intervention for the treatment of vascular restenosis.