覆膜支架治疗主动脉夹层的有限元分析

Finite Element Analysis of Aortic Dissection Treated with Stent Graft

目的利用有限元方法模拟覆膜支架植入治疗主动脉夹层的过程,通过观察覆膜支架在血管不同位置处释放对血管壁上的应力分布情况,分析覆膜支架植入后血管出现新发破口的生物力学机制。方法根据主动脉的计算机断层血管造影影像数据,进行图像分割和三维重建,建立具有病人特异性的主动脉夹层的三维几何模型;根据文献数据,给定主动脉夹层壁厚和材料属性;利用CAD软件设计出不同几何参数的覆膜支架环;利用有限元分析软件模拟覆膜支架的释放过程。结果当覆膜支架处于稳定状态时,血管最大Von Mises应力与覆膜支架的释放位置有关;血管壁上的最大Von Mises应力点分布在裸支架及第1节细小镍钛合金环接触处,该作用力的长期存在可能是这个部位出现新发破口的原因。结论覆膜支架的释放位置对主动脉上的最大Von Mises应力分布影响较弱,但对主动脉上的Von Mises应力影响较为明显。研究结果对临床上覆膜支架释放位置的选择具有指导意义。

Objective To study the process of stent graft implantation into the aortic dissection model by finite element simulation,calculate the stress distribution at different locations of the aorta after the implantation,and analyze the biomechanical mechanism of new lesions for implantation of stent grafts. Methods Based on the computed tomography angiography（ CTA） image data of the aorta,a three-dimensional geometric model of patient-specific aortic dissection was established with image segmentation and reconstruction. The wall thickness and material properties of the aortic dissection of the computational models were set according to the literature data. Stent grafting rings with different geometric parameters were designed in a computer-aided design（ CAD） software,and the procedure of stent graft implantation was simulated by a finite element analysis software. Results When the implanted stent graft reached a steady-state,the maximum Von Mises stress of the aorta was markedly related to the position of the stent graft and located at the bare stent or small nickel-titanium alloy ring. In the long-term,this force might cause a new tear to appear at the treated aorta. Conclusions The position of the stent graft had a weak effect on the distribution of the maximum Von Mises stress of the aorta,but there was an obvious effect on the Von Mises stress of the aorta. These research outcomes may provide significant guidance for selecting the position of the stent graft.