Ecole Nationale Supérieure des Mines de Saint-Etienne, Center for Health Engineering, CNRS UMR 5146, INSERM SFR IFRESIS, Saint-Etienne F-42023, France.
J Mech Behav Biomed Mater. 2012 Jan;5(1):272-82. doi: 10.1016/j.jmbbm.2011.09.006. Epub 2011 Sep 21.
Secondary interventions after endovascular repair of abdominal aortic aneurysms are frequent because stent-graft (SG) related complications may occur (mainly endoleak and SG thrombosis). Complications have been related to insufficient SG flexibility, especially when devices are deployed in tortuous arteries. Little is known on the relationship between SG design and flexibility. Therefore, the aim of this study was to simulate numerically the bending of two manufactured SGs (Aorfix--Lombard Medical (A) and Zenith--Cook Medical Europe (Z)) using finite element analysis (FEA). Global SG behavior was studied by assessing stent spacing variation and cross-section deformation. Four criteria were defined to compare flexibility of SGs: maximal luminal reduction rate, torque required for bending, maximal membrane strains in graft and maximal Von Mises stress in stents. For angulation greater than 60°, values of these four criteria were lower with A-SG, compared to Z-SG. In conclusion, A-SG was more flexible than Z-SG according to FEA. A-SG may decrease the incidence of complications in the setting of tortuous aorto-iliac aneurysms. Our numerical model could be used to assess flexibility of further manufactured as well as newly designed SGs.
腹主动脉瘤血管内修复术后的二级干预很常见，因为支架移植物（SG）相关并发症可能会发生（主要是内漏和 SG 血栓形成）。并发症与 SG 柔韧性不足有关，尤其是当装置在迂曲的动脉中部署时。关于 SG 设计与柔韧性之间的关系知之甚少。因此，本研究的目的是使用有限元分析（FEA）对两种制造的 SG（Aorfix--Lombard Medical（A）和 Zenith--Cook Medical Europe（Z））的弯曲进行数值模拟。通过评估支架间距的变化和横截面变形来研究 SG 的整体行为。定义了四个标准来比较 SG 的柔韧性：最大管腔缩小率、弯曲所需的扭矩、移植物中的最大膜应变和支架中的最大 Von Mises 应力。对于大于 60°的角度，与 Z-SG 相比，A-SG 的这四个标准的值较低。总之，根据 FEA，A-SG 比 Z-SG 更具柔韧性。A-SG 可能会降低在迂曲的腹主动脉-髂动脉瘤情况下发生并发症的概率。我们的数值模型可用于评估进一步制造和新设计的 SG 的柔韧性。
