典型胸主动脉裸支架的力学性能

目的 研究两种胸主动脉镍钛裸支架（Ze、Fa支架）的力学性能，为裸支架的设计和临床选择提供理论依据。方法建立两种裸支架的有限元模型和实物模型。分别完成两种裸支架弯曲、径向力和模拟使用的有限元分析，并进行对应的实物模型测试。通过实测结果验证有限元分析的准确性，预测支架植入后血管的应力和应变。结果 有限元分析表明，Ze、Fa支架弯曲90°时截面扁平率分别为3.83%和18.83%（实测为8.57%和14.27%），弯曲180°时截面扁平率分别为12.02%和23.72%（实测为14.37%和23.35%）。Ze、Fa支架在心脏收缩期最大径向力分别为33、429 N/m（实测为31、433 N/m），在心脏舒张期最大径向力分别为27、146 N/m（实测为29、179 N/m）。Ze、Fa支架在植入后对血管造成的最大应力分别为4、18 kPa,最大应变分别为4.17%和13.92%,最大直径扩张率分别为103%和898%。有限元分析和实测结果无显著性差异（P>0.05）。结论Ze、Fa支架植入后对健康血管造成的最大应力、应变在许可范围内。Ze支架的弯曲性能较优，适合被植入弯曲血管。Ze支架径向力较弱，适合被作为仅提供内膜支撑的Petticoat支架。较强的径向力有助于加强Fa支架在血管内的稳定性，降低脊髓缺血风险，故Fa支架适合被作为限制性裸支架。

Mechanical Properties of Typical Thoracic Aortic Bare Stents

Objective To study mechanical properties of two thoracic aortic bare stents (stent Ze and stent Fa), so as to provide the theoretical basis for the design and clinical selection of bare stents. Methods The finite element models and experimental models of two bare stents were constructed. Finite element analysis (FEA) on bending, radial force, simulated use of the two models were conducted. The accuracy of FEA was verified by experiment result and the vessel stress and strain after stent implantation were predicted. Results The FEA indicated that section flattening rates of stent Ze and stent Fa were 3.83% and 18.83% at 90° bending (8.57% and 14.27% in test results) and 12.02% and 23.72% at 180° bending (14.37% and 23.35% in experiment results). The maximal radial forces of stent Ze and stent Fa were 33 and 429 N/m in systolic phase (31 and 433 N/m in experiment results), and 27 and 146 N/m in diastolic phase (29 and 179 N/m in experiment results). The maximal stresses, strains, and diameter expansion rates of vessels implantation of stent Ze and stent Fa were 4 and 18 kPa, 4.17% and 13.92%, and 1.03% and 8.98%, respectively. There was no significant difference between the FEA and experiment results (P>0.05). Conclusions After implantation of stent Ze and stent Fa, the maximum stress and strain of vessels were within the allowable range. Stent Ze is suitable for curved vessel implantation with a better bending performance. Meanwhile, stent Ze has a lower radial force, and it can provide intimal support as the Petticoat stent with a lower radial force. Stent Fa has a higher radial force, and it can enhance its stability in vessels and reduce the risk of spinal ischemia, thus being suitable for restrictive bare stents.