Nicoud F, Vernhet H, Dauzat M
University Montpellier II-CNRS UMR 5149, CC 051, Montpellier, France.
J Biomech. 2005 Oct;38(10):2019-27. doi: 10.1016/j.jbiomech.2004.09.011.
This theoretical/numerical study aims at assessing the haemodynamic changes induced by endovascular stenting. By using the classical one-dimensional linear pressure waves theory in elastic vessels, we first show that the modulus of the reflection coefficient induced by an endovascular prosthesis is most likely small since it is proportional to the stent-to-wavelength ratio. As a direct consequence, the wall motion of the elastic (stented) artery can be prescribed a priori and the coupled fluid-structure problem does not have to be solved for assessing the haemodynamic changes due to stenting. Several 2D axisymetric calculations are performed to solve the unsteady incompressible Navier-Stokes equations on moving meshes for different types of (stented) arteries. The numerical results suggest that endovascular stenting increases the systo-diastolic variations of the wall shear stress (by 35% at the middle of the stent, by almost 50% in the proximal transition region). Additional calculations show that over-dilated stents produce less haemodynamic perturbations. Indeed, the increase of the amplitude of the wall shear stress variations over the cardiac cycle is only 10% when the stent radius is equal to the radius of the elastic artery at systole (instead of being equal to the mean artery radius).
这项理论/数值研究旨在评估血管内支架置入术引起的血流动力学变化。通过在弹性血管中运用经典的一维线性压力波理论，我们首先表明，血管内假体引起的反射系数模量很可能较小，因为它与支架与波长的比值成正比。直接的结果是，弹性（置入支架的）动脉的壁运动可以预先确定，并且在评估支架置入术引起的血流动力学变化时无需求解流固耦合问题。针对不同类型的（置入支架的）动脉，在移动网格上进行了几次二维轴对称计算，以求解非定常不可压缩纳维-斯托克斯方程。数值结果表明，血管内支架置入术增加了壁面切应力的收缩-舒张变化（在支架中部增加35%，在近端过渡区域几乎增加50%）。额外的计算表明，过度扩张的支架产生的血流动力学扰动较小。实际上，当支架半径等于收缩期弹性动脉半径（而非等于动脉平均半径）时，心动周期内壁面切应力变化幅度的增加仅为10%。
