国家自然科学基金(51735003), 国家自然科学基金( 51901137),上海市科委项目(17441901300)。
目的 针对药物洗脱支架植入后引起的早期再狭窄问题，对镍钛合金血管支架进行结构上的可回收设计和生物力学分析。方法 采用Solidworks软件建立可回收血管支架及其回收系统的几何模型，其中支架回收部为圆台形网状结构，由四个对称分布的回收筋组成；通过有限元方法，对支架的一些重要性能指标（压握过程最大主应变分布、压握及自膨胀均匀性等）进行生物力学研究，并对支架的回收过程进行仿真实验。结果 当支架被压握至最小尺寸时，其最大应变值为3.7%，不均匀性指数为0.62%；当支架自膨胀结束时其不均匀性指数为1.31%；当支架的一半被回收进外鞘管时，其最大应变值为1.52%；而支架在回收过程中并未发生断裂或“卡顿”情况。结论 初步实验表明，从生物力学角度，支架的应变值在其安全范围之内，且支架的压握及自膨胀过程较均匀，能够被安全、顺利地回收进外鞘管中；本文所提出的研究结果可以为可回收血管支架的结构设计、生物力学分析和临床应用提供重要参考依据。
Objective In order to avoid early restenosis after DES implantation, the retrievable structure of the NiTi alloy stent and its biomechanical analysis were studied. Methods The models of the stent and the retrieval system were established using Solidworks. The retrieval structure involving four symmetrically distributed tendons is designed as circular meshes. The primary biomechanical properties of the stent such as the distribution of the maximum strain in the compression process and its uniformity in the compression and self-expansion processes were investigated through the finite element analysis, and the simulation experiments were also performed to study the retrieval process, indicating that no fracture or stumble occurred. Results The maximum strain of the stent was 3.7% and the index of non-uniformity was 0.62% as it was compressed to the minimum size. While the non-uniformity index was 1.31% after the self-expansion process completed. Furthermore, the maximum strain value was 1.52% when half of the stent was retrieved into the outer sheath. Conclusions Results of the preliminary experiments demonstrate that the stent can be safely and successfully retrieved into the outer sheath as the strain value is within the bearable range of the material and the compression and self-expansion process is relatively uniform. Thus, this paper presents our more recent efforts on the study of a new type of retrievable vascular stent, which provides an in-depth understanding of the structural design, biomechanical analysis as well as its potential clinical applications.