Xu Jiang, Yang Jie, Sohrabi Salman, Zhou Yihua, Liu Yaling
School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China e-mail:
Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015 e-mail:
J Med Device. 2017 Jun;11(2):0210101-210109. doi: 10.1115/1.4036391. Epub 2017 May 3.
Overlapping stents are widely used in vascular stent surgeries. However, the rate of stent fractures (SF) and in-stent restenosis (ISR) after using overlapping stents is higher than that of single stent implantations. Published studies investigating the nature of overlapping stents rely primarily on medical images, which can only reveal the effect of the surgery without providing insights into how stent overlap influences the implantation process. In this paper, a finite element analysis of the overlapping stent implantation process was performed to study the interaction between overlapping stents. Four different cases, based on three typical stent overlap modes and two classical balloons, were investigated. The results showed that overlapping contact patterns among struts were edge-to-edge, edge-to-surface, and noncontact. These were mainly induced by the nonuniform deformation of the stent in the radial direction and stent tubular structures. Meanwhile, the results also revealed that the contact pressure was concentrated in the edge of overlapping struts. During the stent overlap process, the contact pattern was primarily edge-to-edge contact at the beginning and edge-to-surface contact as the contact pressure increased. The interactions between overlapping stents suggest that the failure of overlapping stents frequently occurs along stent edges, which agrees with the previous experimental research regarding the safety of overlapping stents. This paper also provides a fundamental understanding of the mechanical properties of overlapping stents.
重叠支架在血管支架手术中被广泛应用。然而，使用重叠支架后的支架断裂（SF）和支架内再狭窄（ISR）发生率高于单支架植入。已发表的关于重叠支架性质的研究主要依赖医学图像，这些图像只能揭示手术效果，而无法深入了解支架重叠如何影响植入过程。本文对重叠支架植入过程进行了有限元分析，以研究重叠支架之间的相互作用。基于三种典型的支架重叠模式和两种经典球囊，研究了四种不同情况。结果表明，支柱之间的重叠接触模式为边对边、边对表面和非接触。这些主要是由支架在径向方向上的不均匀变形和支架管状结构引起的。同时，结果还表明接触压力集中在重叠支柱的边缘。在支架重叠过程中，接触模式开始时主要是边对边接触，随着接触压力增加变为边对表面接触。重叠支架之间的相互作用表明，重叠支架的失效经常发生在支架边缘，这与先前关于重叠支架安全性的实验研究一致。本文还提供了对重叠支架力学性能的基本理解。
