Aragón Institute of Engineering Research, University of Zaragoza, Spain.
J Mech Behav Biomed Mater. 2012 Jun;10:166-75. doi: 10.1016/j.jmbbm.2012.02.006. Epub 2012 Feb 18.
The goal of this work is to study the influence of the main geometrical parameters on the radial force of a self-expanding stent, and using them to advance towards a new design of a variable radial force stent to improve the interaction vessel-device. Using finite element simulations, a parametric analysis of a commercial stent model (Acculink, Abbot Vascular) was developed to estimate the influence of geometrical variables, mainly radial and circumferential strut thicknesses and the initial diameter of the stent. The radial expansion force was compared for the different values of each geometrical variable. The previous results were used to propose a new stent design with variable radial stiffness. Their effects on healthy and atheromatous vessels were studied and compared for both stent models, constant and variable radial stiffness respectively. The developed analysis reveals a notable decrease of the contact pressure over the inner arterial wall in healthy areas using a variable radial force (VF) stent with respect to the same model with a constant expansion force (CF) stent. In the case of a vessel model with a fibrotic core plaque, the lumen healthy areas that suffer a contact pressure higher than 0.25 MPa are reduced from 36.86% to 22.38% for the left healthy area (LHA), and from 40.13% to 21.36% in the right healthy area (RHA). Furthermore, this pressure reduction in the healthy areas does not cause a decrease in the expansion pressure in an atheromatous section, where it is necessary to maintain a recovery of the lumen section. In the case of lipid core, the flow section with plaque is 70.8% of the healthy flow section using a VF stent, and 70.9% with a CF stent, while 66.87% and 66.89% were found respectively in the case of a calcified core.
这项工作的目的是研究主要几何参数对自膨式支架径向力的影响，并利用这些参数来设计一种新的可变径向力支架，以改善血管-器械的相互作用。通过有限元模拟，对一种商业支架模型（Acculink，Abbot Vascular）进行了参数分析，以评估几何变量（主要是径向和周向支柱厚度以及支架的初始直径）的影响。比较了不同几何变量值下的径向膨胀力。根据先前的结果，提出了一种新的具有可变径向刚度的支架设计。研究并比较了这两种支架模型（分别为恒定和可变径向刚度）在健康和粥样硬化血管中的效果。所开发的分析表明，与具有恒定膨胀力（CF）的支架相比，在健康区域使用可变径向力（VF）支架可显著降低内动脉壁的接触压力。在具有纤维化核心斑块的血管模型中，承受接触压力高于 0.25 MPa 的健康区域面积从左健康区域（LHA）的 36.86%减少到 22.38%，从右健康区域（RHA）的 40.13%减少到 21.36%。此外，这种健康区域压力的降低不会导致动脉粥样硬化区域的扩张压力降低，而在动脉粥样硬化区域有必要保持管腔截面的恢复。在脂质核心的情况下，使用 VF 支架时，带有斑块的流动截面占健康流动截面的 70.8%，而使用 CF 支架时则占 70.9%，而在钙化核心的情况下则分别为 66.87%和 66.89%。
