%0 Journal Article
%T 两种覆膜支架的生物力学对比分析
%A 谷雪莲
%A 胡方遒
%A 于凯
%A 李中华
%A 宋成利
%J 医用生物力学
%D 2015
%R 10.3871/j.1004-7220.2015.05.410
%X 目的 应用数值模拟方法研究两种直管型覆膜支架在植入过程中自膨胀释放、平衡状态、支架弯曲3种工况下的生物力学特性，并对比支架结构变化对其各生物力学指标的影响。方法建立两款环状覆膜支架（支架Ⅰ、II，其中支架II各独立支架单元间添加连杆加固）和目标血管的有限元模型。使用输送鞘将支架输送到目标血管中，释放输送鞘使支架自膨胀释放，并建立血管和覆膜支架的接触关系；释放完全后，在支架内表面施加6.65~19.95 kPa（50~150 mmHg）动脉压；在支架两端施加角位移以使其弯曲变形。最后分析变形血管的等效应力峰值，覆膜支架在各工况下的最大主应变峰值、等效应力峰值及形态的变化。结果 在自膨胀释放过程中，支架Ⅰ、II造成血管壁应力集中的峰值分别为0.349、0.371 MPa；平衡状态中，支架Ⅰ、II平均应变分别为0.086%、0.053%，振荡应变分别为0.049%、0.027%，覆膜应力峰值分别为2.098、2.430 MPa；支架弯曲变形时，支架Ⅰ、II最大主应变峰值分别为0.069%、0.101%，覆膜变化形态上支架Ⅰ褶皱更为严重。结论 两种覆膜支架在各状态下应力应变都满足相应材料屈服极限；支架II由于单元间存在连杆而使其在释放过程中具有更大的径向支撑力，动脉压作用下具有较低应变水平，支架弯曲变形时也能具备更好的贴壁性。研究结果可以为覆膜支架的结构设计以及覆膜材料选择提供一种分析方法，并给临床覆膜支架介入手术操作提供直观、准确的技术指导。</br>Objective To study biomechanical properties of two types of cylindrical nitinol stent-grafts under working condition of self-expanding, full deployment and bending, and analyze effects of structural change on biomechanical indexes of the grafts by numerical simulation methods. MethodsFirstly, the finite element models of two annular stent-grafts (i.e. stent-graft Ⅰ, stent graft Ⅱ, and a connecting rod was added to each stent unit of stent-graft Ⅱ for reinforcement) and target vessels were built. The stent-graft was transported to target vessel by delivery sheath, which was then removed to self-expand the stent-graft, and the contact between the vessel and the stent-graft was established. Secondly, the arterial pressure of 6.65-19.95 kPa (50 150 mmHg) was applied to inner surface of the stent-graft when the stent graft was fully deployed. Thirdly, the angular displacement was applied to both ends of the stent-graft to bend and deform the stent-graft. Finally, the maximum Von Mises stress (VMS) of the deformed vessel, the maximum principal strain (MPS), the maximum VMS and structural changes of the stent-graft were analyzed. ResultsFor both the stent-graft Ⅰ and Ⅱ, when they were self-expanding, the maximum VMS on the vessel was 0.349 MPa and 0.371 MPa, respectively; when they were fully deployed, the mean strain was 0.086% and 0.053%, the alternating strain was 0.049% and 0.027%, the maximum VMS on the membrane was 2.098 MPa and 2.430 MPa, respectively; when they were bent, the MPS was 0.069% and 0.101%, respectively, with more serious deformation on stent-graft Ⅰ. ConclusionsThe strain and stress of two stent-grafts under each working condition were less than their own material yielding limit. Stent-graft Ⅱ showed larger radial force in self-expanding, smaller strain under arterial pressure and better flexibility in bending deformation due to its connecting rod between each stent unit. These research results would provide an
%K 覆膜支架
%K 腹主动脉瘤
%K 镍钛合金
%K 数值模拟
%K 力学特性&lt
%K /br&gt
%K Stent-graft
%K Abdominal
%K aortic
%K aneurysm
%K Nitinol
%K alloy
%K Numerical
%K simulation
%K Biomechanical
%K properties
%U http://www.mechanobiology.cn/yyswlx/ch/reader/view_abstract.aspx?file_no=201505005&flag=1