Atualização sobre endopróteses vasculares (stents): dos estudos experimentais à prática clínica

Mechanical characteristics of braided composite stents for carotid artery stenosis using finite element method

Self-expandable braided stents are widely used for carotid artery stenosis due to flexibility. Finite element (FE) models of braided composite stents with different proportions of NiTi and Mg-2.1Nd-0.2Zn-0.5Zr (JDBM) alloy (24NiTi (24:0), 20NiTi (20:4), 16NiTi (16:8), 12NiTi (12:12), 8NiTi (8:16), 4NiTi (4:20)) were constructed to analyze their radial compression strength and longitudinal bending flexibility. The 4NiTi stent showed the highest radial support (16.39N) and decreased bending strength by 7.72%. These results suggest that replacing more NiTi with JDBM wires enhances the stent's radial strength and reduces bending stiffness, providing new insights into stent design.

A hazardous boundary of Poly(L-lactic acid) braided stent design: Limited elastic deformability of polymer materials

Poly (L-lactic acid) (PLLA) braided stents, which are expected to replace metal stents, are promising in peripheral vascular therapy due to their superior biocompatibility. Although various design ideas have been proposed and investigated on metal stents, few researches are related to the design theory of PLLA braided stent. In this article, mechanical performance of PLLA braided stents with different parameters was systematically evaluated, and a design theory based on material properties was proposed. Different from metal materials, the risk of filament deformation beyond elastic zone should be evaluated and controlled in PLLA stent design. The findings were obtained through combination study of experiments and simulations. Design parameters, including pitch angle and stent diameter, played a crucial role in mechanical performance of PLLA braided stent. The deformation of PLLA stents with larger pitch angles and stent diameters was in elastic zone and thus presented better mechanical performance with satisfactory resilience. This work could provide meaningful suggestions for preparing bioresorbable braided stents with suitable design parameters.