Hemodynamic analysis of edge stenosis in peripheral artery stent grafts

Purpose: The purpose of this study was to characterize the hemodynamics of peripheral artery stent grafts to guide intelligent stent redesign.

Materials and methods: Two surgically explanted porcine arteries were mounted in an ex vivo system with subsequent deployment of an Xpert self-expanding nitinol stent or Viabahn stent graft. The arteries were casted with radiopaque resin, and the cast then scanned using micro-computed tomography at 8μm isotropic voxel resolution. The arterial lumen was segmented and a computational mesh grid surface generated. Computational fluid dynamics (CFD) analysis was subsequently performed using COMSOL Multiphysics 5.1.

Results: CFD analysis demonstrated low endothelial shear stress (ESS) involving 9.4 and 63.6% surface area of the central stent graft and bare metal stent, respectively. Recirculation zones were identified adjacent to the bare metal stent struts, while none were identified in the central stent graft. However, the stent graft demonstrated malapposition of the proximal stent graft edge with low velocity flow between the PTFE lining and arterial wall, which was associated with longitudinally and radially oriented recirculation zones and low ESS.

Conclusion: Computational hemodynamic analysis demonstrates that peripheral artery stent grafts have a superior central hemodynamic profile compared to bare metal stents. Stents grafts, however, suffer from malapposition at the proximal stent edge which is likely a major contributor to edge stenosis.