Abrasion behaviour of polymeric textiles for endovascular stent-grafts

Endovascular aneurysm repair (EVAR) is a type of endovascular surgery used to treat abdominal aortic aneurysms (AAA). The prosthesis used for the purpose, called stent-grafts, are made of polymeric materials reinforced by metallic stents. The polymers used for the graft construction are usually woven PET fibres or extruded ePTFE. After implantation and due to blood flow and to the relative motion between the stent and the graft, abrasion, erosion and fatigue of the graft material can occur, leading to fibre separation/fracture and perforation of the graft. In this paper, abrasion wear tests results are presented for three different materials used in stent–grafts, using the Martindale method. Mass loss as function of wear cycles is presented. Scanning electron microscopy, before and after tests was used to analyse the materials surface. ePTFE specimens presented ruptures between 45,000 and 55,000 cycles and PET specimens at 70,000 cycles. PET-LP (low profile) specimens did not reveal any rupture until 150,000 cycles. These results show an increased life resistance, due to different wear mechanisms of PET-LP fabric, when compared with ePTFE and PET fabric for vascular prosthesis applications.