室间隔缺损封堵器的有限元建模及分析

目的 分析编织角度与材料对室间隔缺损（ventricular septal defect, VSD）封堵器使用效果的影响，为器械设计提供理论依据与指导。方法 建立3种编织角度（30°、45°、60°）封堵器的有限元模型，分析比较两种编织材料镍钛合金（nickel titanium, NiTi）、聚对二氧环已酮（poly-p-dioxanone, PPDO）封堵器在腰部分别受径向和轴向载荷下的支撑效果。结果 5 kPa径向载荷下，30°、45°、60°NiTi封堵器的腰部径向刚度分别为8.60、1.51、0.99 mN/mm3，45° PPDO封堵器腰部径向刚度为7.35 mN/mm3。0.5 rad轴向弯曲下：30°、45°、60° NiTi封堵器腰部最大径向形变分别为1.17、1.24、0.22 mm，45° PPDO封堵器腰部最大径向形变为0.54 mm。结论 同种材料情况下，编织角度为60°的封堵器腰部径向刚度最小，径向支撑性能最佳；60°封堵器腰部最大径向形变最小，轴向弯曲性能最佳，顺应性最好。同种编织角度情况下，NiTi封堵器腰部径向刚度较小，径向支撑性能较佳；PPDO封堵器腰部最大径向形变较小，轴向弯曲性能较佳，顺应性较好。
Objective To analyze influences of the braiding angle and material on performance of ventricular septal defect (VSD) occluders, so as to provide theoretical basis and guidance for their design. Methods The finite element models of occluders with different braiding angles (30°, 45° and 60°) were developed respectively. The radial supporting and axial bending performances of nickel titanium (NiTi) occlude and poly-p-dioxanone (PPDO) occlude were then compared. Results Under 5 kPa radial loading, radial stiffness of the 30°, 45° and 60° NiTi occluder waists were 8.60, 1.51 and 0.99 mN/mm3,respectively, while that of 45° PPDO occluder waist was 7.35 mN/mm3. Under axial bending of 0.5 rad, the maximum radial deformation of the 30°, 45°, 60° NiTi occluder waists were 1.17, 1.24 and 0.22 mm, while that of the 45° PPDO was 0.54 mm. Conclusions Under the condition of using the same material, occluders with braiding angle of 60° show the lowest radial stiffness, indicating they have the best radial supporting ability. Furthermore, they also show the smallest maximum radial deformation, indicating they have the best axial bending ability and the compliance. On the other hand, under the condition of using the same braiding angle, NiTi occluders show lower radial stiffness, indicating they have better radial supporting ability. However, PPDO occluders show lower maximum radial deformation, indicating they have better axial bending ability and compliance.