调控支架构型预防主动脉弓部夹层平行支架术后内漏的生物力学研究

Biomechnical study of manipulating the configuration of the stent-graft to prevent endoleak after parallel stent technique treating aortic arch dissection

目的通过改变主体支架构型并在体外模拟和力学测试下筛选支架优化构型,为进一步提高平行支架技术的临床效果提供科学的实验依据和应用指导。方法建立5种适于烟囱技术的支架移植物模型,结合支架丝粗细、支架口径、冠数、波幅等参数,在有限元分析下测量5种支架移植物与烟囱支架作用后产生的缝隙大小。制作相应单环支架后进行体外释放、CT扫描及管壁应力分析,进一步验证有限元分析结果。结果有限元计算不同结构下P(波头数平均分布8个,波幅为15 mm)、P1(波头数为单边4个+单边8个,波幅为10 mm)、P2(波头数为单边4个+单边8个,波幅为15 mm)、P3(波头数为单边4个+单边12个,波幅为10 mm)、P4(波头数为单边4个+单边12个,波幅为15 mm)的缝隙面积分别为45.58 mm2、16.46 mm2、38.24 mm2、23.96 mm2、42.08 mm2(P4)。支架对血管壁应力分析评估管壁破裂风险方面,支架P1与P2在支架贴附良好的同时不会增大管壁应力。体外模拟释放中发现,支架P1和P2展开与贴附均较好,支架P3与P4都不同程度出现了支架折叠及倾斜的现象。CT扫描结果为(47.49±1.44)mm2 (P)、(19.55±0.98)mm2 (P1)、(40.05±1.05) mm2 (P2)、(27.77±0.90)mm2(P3)、(50.99±1.47)mm2(P4)。结论从缝隙面积有限元分析、CT扫描、支架与管壁应力分析及制作可行性综合考虑,P1结构方案最优。该支架移植物仍然需要更细致地进行材料及结构优化,体外模拟实验和动物实验仍需验证其安全性及可行性。

Objective To investigate on how to prevent it after parallel stent technique(PST) has been least carried out. By manipulating the stent configuration and In vitro simulation and mechanical test,the optimized configuration was screened out. This study will provide important insight on the endoleak after parallel stent technique in the aortic arch. As biomechanical rationales of endovascular treatment of aortic dissection, the outcomes of this study may have great clinical potential. Methods 5 models of stent-graft suitable for PST were established. Combined with parameters such as wire diameter, caliber, crown number and wave amplitude, gutter in different stent configuration were measured in finite element analysis. In vitro release, CT scan and the pressure stress of tube wall, the single ring stents were made to further verify the results of the finite element analysis. Results The finite element calculation of the gutter area under stent configuration were 45.58 mm2(P), 16.46 mm2(P1), 38.24 mm2(P2), 23.96 mm2(P3), 42.08 mm2(P4).The risk evaluation of wall rupture from stress analysis of stent on vascular wall revealed that stent P1 and P2 are well attached to the vessel wall without increasing stress. It was found in vitro that P1 and P2 were well expanded and attached to the wall while folding and tilting of the stent were both found in stent P3 and P4. The results of CT scan were 47.49±1.44 mm2(P), 19.55±0.98 mm2(P1), 40.05±1.05 mm2(P2), 27.77±0.90 mm2(P3), 50.99±1.47 mm2(P4). Conclusion Considering the finite element analysis of gutter area,CT scan, pressure stress of tube wall and production feasibility, the P1 structure was optimal. Manipulating the configuration of the stent-graft still needs more detailed material and structure optimization. In vitro simulation experiment and animal experiment need to verify its safety and feasibility.