A magnetic approach to decrease stent graft endoleak: ex-vivo validation

Stent graft endoleak is a major problem in endovascular aneurysm repair (EVAR). Endoleak occurs after EVAR and may lead to aneurysm rupture, acute vessel thrombosis or occlusion. This study presents a novel design to potentially reduce endoleak with use of magnets. A ferromagnetic stent is deployed into the vessel lumen, and two external flexible magnetic rings are used to clamp on the proximal and distal necks of the stent. The rings impose epivascular magnetic pressure on the vessel wall to prevent the vessel wall from separating from the stent under elevated blood pressure. The geometry and magnetic properties of the stent and rings were designed to produce sufficient pressure, without overly compressing the vessel wall. Feasibility of this design was demonstrated with in vitro experiments using porcine abdominal aortas. The experiments showed that magnetic ring significantly improved the seal between the stent and vessel wall with use of moderate-sized stent. For aortas subjected to physiological axial stretch, rings that generate magnetic pressure of about 45 mmHg were found sufficient to prevent endoleak at pressure of 140 mmHg. Evaluation of this design in an in vivo animal model of aortic aneurysm is warranted.