Fu Wenyu, Xia Qixiao, Yan Ruobing, Qiao Aike
College of Mechanical and Electrical Engineering, Beijing Union University, Beijing 100020, China.
College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China.
Biomed Mater Eng. 2018;29(1):81-94. doi: 10.3233/BME-171714.
Braided stents, such as Pipeline Embolization Device (PED; ev3 Neurovascular, Irvine, CA, USA), are commonly used to treat cerebral aneurysms. However, little information is available on the compression and bending characteristics of such stents.
This paper investigates how geometrical parameters of braided stents influence their radial compression and bending characteristics.
Six groups of braided stent models with different braiding angles, numbers of wires and wire diameters are constructed. Parametric analyses of these models are conducted using Abaqus/Explicit software. The numerical results of a finite element analysis are validated by comparison with data of theoretical analysis.
The results show that the radial stiffness is not uniform along the longitudinal direction of the stent. When the braiding angle increases from 30° to 75°, the minimum radial deformation decreases from 0.85 mm to 0.0325 mm (at a pressure of 500 Pa, for 24 braided wires). When the wire diameter increases from 0.026 mm to 0.052 mm, the minimum radial deformation decreases from 0.65 mm to 0.055 mm (at a pressure of 500 Pa and a braiding angle of 60°, for 24 braided wires). Frictions don't affect stent diameter and its axial length when braided stent is crimping, but the friction must be considered when it is related to the radial pressure required for compression the braided stent.
Compared with commonly used intracranial stents, a braided stent with geometrical parameters close to PED stent has a smaller radial stiffness but a considerably greater longitudinal flexibility. The results of this analysis of braided stents can help in the design and selection of flow diverter stents for clinical treatment of cerebral aneurysms.
编织型支架，如Pipeline栓塞装置（PED；ev3神经血管公司，美国加利福尼亚州欧文市），常用于治疗脑动脉瘤。然而，关于此类支架的压缩和弯曲特性的信息却很少。
本文研究编织型支架的几何参数如何影响其径向压缩和弯曲特性。
构建六组具有不同编织角度、金属丝数量和金属丝直径的编织型支架模型。使用Abaqus/Explicit软件对这些模型进行参数分析。通过与理论分析数据进行比较，验证有限元分析的数值结果。
结果表明，支架径向刚度沿纵向方向并不均匀。当编织角度从30°增加到75°时，最小径向变形从0.85毫米降至0.0325毫米（对于24根编织金属丝，在500帕压力下）。当金属丝直径从0.026毫米增加到0.052毫米时，最小径向变形从0.65毫米降至0.055毫米（对于24根编织金属丝，在500帕压力和60°编织角度下）。在编织型支架压接时，摩擦力不影响支架直径及其轴向长度，但在涉及压缩编织型支架所需的径向压力时必须考虑摩擦力。
与常用的颅内支架相比，几何参数接近PED支架的编织型支架具有较小的径向刚度，但纵向柔韧性明显更大。这种编织型支架的分析结果有助于用于脑动脉瘤临床治疗的分流支架的设计和选择。
