Engineering <i>In Situ</i> Weldable Vascular Devices

Abstract

Endovascular Aneurysm Repair (EVAR) procedures are based on the implantation of a stent graft consisting of a metallic stent and a polymeric fabric attached to it. A leading trend fueling much research activity in this field is the minimization of the insertion profiles of the stent grafts used. Aiming at solving the key problems marring current stent grafts, a stenting strategy whereby the metal stent and the graft are deployed sequentially and welded together at the aneurysmal site is presented. Decoupling the stent and the graft greatly reduces the stent graft profile, which largely eases insertion and increases maneuverability through hostile anatomies. To render the metallic stent in vivo weldable, its struts were coated with an in vivo weldable polymer. Polyurethane thermoplastic elastomers were used to generate the graft - called in this study the sleeve - and to coat the stent struts, and their composition was fine-tuned, to optimize their welding properties. The device was successfully implanted in pigs through an 8F introducer, remarkably smaller than the 14-18F introducers currently used in the clinic. In situ welded devices implanted in pigs for 3 months were navigated to the site and deployed straightforwardly and demonstrated that the strength of the welded connection was retained, with no de-welding being observed. To our knowledge, this is the first time that the welding phenomenon is performed inside the body.