Praveen Kumar Gideon, Liang Leo Hwa, Cui Fangsen
a Institute of High Performance Computing, A*STAR , Singapore.
b Department of Biomedical Engineering , National University of Singapore , Singapore.
Comput Methods Biomech Biomed Engin. 2019 Apr;22(5):533-546. doi: 10.1080/10255842.2019.1569636. Epub 2019 Feb 18.
To design a hooked self-expandable caval valve stent and determine the best crimping scenario for its percutaneous implantation in the Superior and Inferior Vena Cava (SVC & IVC) for the treatment of tricuspid regurgitation (TR). A hooked, Nitinol based stent design was modeled using SOLIDWORKS and finite element analysis (FEA) was carried out using ABAQUS. The Nitinol material used in this study was modeled in ABAQUS as superelastic-plastic. Two cases were simulated. In case A, the stent model was crimped to 18 F by compressing the stent main body and then: (i) bending both the proximal and distal hooks; (ii) straightening the proximal hooks and bending the distal hooks. In case B, the stent model was crimped to 18 F by: (i) bending the proximal and distal hooks and then compressing the stent main body; (ii) straightening the proximal hooks and bending the distal hooks and then compressing the stent main body. The maximum strain after crimping was used to evaluate the best crimping scenario. Hook straightening produced strains of 10.7% and 10.96% as opposed to 12.6% and 13.0% produced by hook bending. From comparison of results of both cases simulated, it was found that straightening the hooks gave lower strain and thus was the best crimping procedure. The analysis performed in this paper may help understand the critical issue of crimpability of the new stent design. The best crimping scenario can be found based on finite element modeling and simulation. Identifying the best crimping way will also help the design team to optimize the delivery system that will eventually be used to deploy this caval valve stent.
设计一种带钩的自膨胀腔静脉瓣膜支架，并确定其经皮植入上、下腔静脉（SVC和IVC）治疗三尖瓣反流（TR）的最佳压接方案。使用SOLIDWORKS对基于镍钛诺的带钩支架设计进行建模，并使用ABAQUS进行有限元分析（FEA）。本研究中使用的镍钛诺材料在ABAQUS中被建模为超弹塑性材料。模拟了两种情况。在情况A中，通过压缩支架主体将支架模型压接到18F，然后：（i）弯曲近端和远端钩；（ii）拉直近端钩并弯曲远端钩。在情况B中，通过以下方式将支架模型压接到18F：（i）弯曲近端和远端钩，然后压缩支架主体；（ii）拉直近端钩并弯曲远端钩，然后压缩支架主体。压接后的最大应变用于评估最佳压接方案。钩拉直产生的应变分别为10.7%和10.96%，而钩弯曲产生的应变分别为12.6%和13.0%。通过对两种模拟情况结果的比较，发现拉直钩产生的应变较低，因此是最佳压接程序。本文进行的分析可能有助于理解新支架设计的可压接性这一关键问题。基于有限元建模和模拟可以找到最佳压接方案。确定最佳压接方式也将有助于设计团队优化最终用于部署这种腔静脉瓣膜支架的输送系统。
