Elastic recovery of polymeric braided stents under cyclic loading: Preliminary assessment

Over the last decades, stents have been largely used to treat vascular diseases such as coronary artery or peripheral vessel stenosis. Among the solutions which are commercially available to treat vascular stenosis, metallic stents represent the gold standard. However, issues such as restenosis, corrosion and fractures have been reported with these devices and are especially due to the material which is used. Braided polymeric stents could present an alternative to replace metallic stents especially in peripheral vessels where flexibility is required. Among polymeric materials, polyethylene terephthalate (PET), could be a good candidate as its biocompatibility has already been widely proven especially in the field of cardiovascular applications. Moreover, braided devices have been already used for the stenting of peripheral zones, providing locally outstanding flexibility due to the discontinuity of these structures. The goal of this work was to evaluate the radial strength and the recovery performances of polymeric braided stents made from PET monofilaments. In particular, the behavior of these stents under repeated cyclic radial compression loading was assessed and compared to results obtained with a metallic braided stent of same diameter. Results show that polymeric braided stents provide 100% elastic recovery after 20% diameter compression over 2000 repetitive loading cycles. However, radial strength goes slightly down with cycling, which points out that friction occurs in the braid. It comes out from the study that a braided polymer stent shows suitable mechanical behavior compared to a metallic stent over cyclic loading up to 2000 cycles. Moreover, it is shown that the mechanical behavior of these stents depend highly on the braid angle.