支架作用下主动脉血管壁有限元应力分析
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1.天津大学机械学院;2.天津医科大学总医院 普通血管外科;3.首都医科大学附属北京安贞医院 心脏中心

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国家自然科学基金面上项目(11872267),天津市自然科学基金青年项目(18JCQNJC14400)


A finite element stress simulation of aortic vessels under stent graft
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1.Department of Mechanics,Tianjin University;2.Department of Surgery,Tianjin Medical University General Hospital;3.Heart Center,Beijing Anzhen Hospital Affiliated to Capital Medical University;4.China

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    摘要:

    目的 利用有限元方法模拟主动脉覆膜支架与考虑残余应力的主动脉血管壁的耦合作用,研究支架对主动脉血管壁应力分布的影响。方法 采用应力驱动的主动脉各向异性生长模型,降低轴向和周向跨壁应力均匀分布,从而在理想化双层主动脉模型中生成三维残余应力场;建立覆膜支架模型实现其虚拟植入;对覆膜支架作用下的主动脉血管壁进行应力分析。结果 残余应力场对应的主动脉张开角117.5°在正常范围内,残余应力的存在降低了血管壁在周向和轴向的跨壁应力梯度。支架作用下血管壁的应力最大值位于覆膜支架波峰与血管壁接触处。支架放大率为20%时,血管壁周向应力最大值为412kpa,轴向应力最大值为132.1kPa,面内剪切应力 为77.5kpa、 为77.8kpa,且应力最大值与支架放大率成正比。残余应力作用下,径向应力、环向应力与轴向应力最大值分别下降14.9%、40.5%和33.8%,剪应力最大值分别下降2.5%、7.1%、27.0%,放大率从10%增加到20%,径向应力、环向应力与轴向应力最大值分别增加316%,129%,41%,剪应力最大值分别增加661%,450%,466%。结论 残余应力有效降低了血管壁应力梯度。残余应力和支架放大率对血管壁的应力分布及应力最大值有较大影响。本研究可为支架源性新破口和夹层扩展的力学机理研究提供帮助,同时为手术方案及覆膜支架优化设计提供理论支撑。

    Abstract:

    Objective To study the stent graft coupling with the aortic vessel considering residual stress model by finite element simulation, calculate the stress distribution of the aorta vessel after the coupling with the stent graft. Methods A stress-induced aorta anisotropic growth vessel model was used to homogenize transmural stress distribution in both axial and circumferential directions,three dimensional residual stresses are generated in the bilayer cylindrical idealized aortic model;Stent grafts were designed;and analysis the stress state of the vessel wall coupling with the stent graft. Results The residual stress field corresponds to the aortic opening Angle 117.5°within the normal range, the presence of residual stress reduces the circumversely and axially cross-wall stress gradient of the vascular wall. The maximum stress of the vessel was located at the contact position between the stent wave and the vessel wall. When the oversize of the stent was 20%, the maximum circumferential stress of the vessel wall was 412kpa, the maximum axial stress is 132.1kpa, the in-plane shear stress is 77.5kpa and 77.8kpa, Sand the maximum stress is proportional to the oversize of the stent.Under the residual stress, the maximum values of radial stress, circumferential stress and axial stress decreased by 14.9%, 40.5% and 33.8%, respectively. The maximum shear stress decreased by 2.5%, 7.1% and 27.0%, respectively.The oversize of the stent increased from 10% to 20%,the maximum values of radial stress, circumferential stress and axial stress increased by 316%, 129%, 41%, respectively. The maximum shear stress increases by 661%, 450% and 466% , respectively. Conclusions Residual stress effectively reduced the stress gradient of vascular wall. Residual stress and the oversize of stent graft have a great influence on the stress distribution and maximum stress value of vessel wall.The results provide help for analyzing the mechanism of new entry and propagation of aortic dissection for implantation of stent grafts, and the optimization design of stent graft,as well as theoretical calculation reference for the optimal design of surgical procedure and stent graft .

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  • 收稿日期:2019-11-19
  • 最后修改日期:2020-02-08
  • 录用日期:2020-02-21
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