支架作用下主动脉血管壁应力分析
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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)


Stress Analysis of Aortic Vessels under Stent Graft
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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梯度,从而在理想化健康人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。支架作用下血管壁最大应力位于覆膜支架波峰与血管壁接触处。支架放大率为20%时,血管壁最大周向、轴向应力分别为412、132 kPa,面内切应力σrθ、σrz均为78 kPa。残余应力作用下,最大径向、周向与轴向应力分别下降14.9%、40.5%和33.8%,最大切应力σrθ、σrz和σθz分别下降2.5%、7.1%、27.0%。支架放大率从10%增加到20%,最大径向、周向与轴向应力分别增加316%、129%、41%,最大切应力σrθ、σrz和σθz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最大应力有较大影响。

    Abstract:

    Objective To simulate the interaction between the stent graft (SG) and the aortic wall with finite element (FE) analysis by considering the influence of residual stress field, so as to study the stent influence on stress distributions of the aortic wall. Methods The three-dimensional (3D) residual stress field was generated in an idealized bi-layered thick-wall aortic model via a stress-driven anisotropic growth model by reducing the transmural stress gradient. Upon virtually deploying the SG, the stress on the aortic wall was calculated. Results The 3D residual stress field, corresponding to an opening angle of 117.5°, was shown to reduce the transmural stress gradient in both the circumferential and axial directions. The maximum stress was found at the contact area between aortic wall and wave peak of the stent. At 20% oversize ratio of the stent, the maximum stresses on the aortic wall in circumferential and axial direction were 412 and 132 kPa, respectively, while the in-plane shear stresses σrθ and σrz were both 78 kPa. Under residual stress, the maximum radial, circumferential and axial stresses were decreased by 14.9%, 40.5% and 33.8%, respectively, while the maximum shear stresses σrθ ,σrz,σθz were reduced by 2.5%, 7.1% and 27%, respectively. With the increase of oversize ratio from 10% to 20%, the maximum radial, circumferential and axial stresses were increased by 316%, 129% and 41%, respectively, while the maximum shear stresses σrθ ,σrz,σθz were increased by 661%, 450% and 466%, respectively. Conclusions The residual stress can effectively reduce the transmural stress gradient. Both the residual stress and the oversize ratio of the stent play an important role in modulating the wall stress distribution and the maximum stress.

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杨帅星,张明,戴向晨,薛玉国,刘浩飞.支架作用下主动脉血管壁应力分析[J].医用生物力学,2021,36(1):14-21

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  • 收稿日期:2019-11-19
  • 最后修改日期:2020-01-10
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  • 在线发布日期: 2021-02-26
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