The Effect of Aortic Endovascular Graft Oversizing on Barb Penetration and Fixation Strength

Endovascular repair of abdominal aortic aneurysm (AAA), where an endovascular graft (EVG) — a stented vascular graft — is implanted intraluminally into the AAA has shown excellent short term outcome. However, long term outcome of implanted EVGs is fraught with new complications, the most severe of which is endoleak from graft migration, which can lead to re-pressurization of the AAA and potentially rupture. Graft migration is defined as the distal drift of an implanted EVG of 5mm or more from its initial anchor site (Figure 1). There have been many design changes to help decrease the rate of EVG migration including the addition of proximal attachment barbs to grafts to help secure them to the aortic wall. However, studies show that freedom from migration rates have not significantly increased for those grafts containing barbs compared to grafts without barbs [1]. We believe that controlled studies of endovascular graft parameters can lead to improvements in its design that increase graft attachment strength and hence decrease the risk of migration. The aim of the current study was to assess a key design variable in barbed grafts namely, graft oversizing (GO), defined as the ratio of expanded graft dia to aorta dia. We sought to assess the relationship between GO and attachment strength in barbed EVGs. Specifically, we hypothesized that a high GO will impede the ability of the EVG barbs to effectively penetrate the aortic wall.