Macroporous polyester-covered stent in an experimental abdominal aortic aneurysm model.

Abstract

To validate a recently described animal model of abdominal aortic aneurysm (AAA) and to assess a new macroporous polyester-covered stent for endovascular AAA exclusion. Twenty adult sheep had AAAs surgically created by replacing a segment of the infrarenal aorta with an autologous jugular venous graft. Three months later, surviving animals underwent percutaneous implantation of macroporous polyester-covered nitinol stents; 3 animals with untreated AAAs served as controls. Follow-up surveillance included spiral computed tomography at 1 month and digital subtraction angiography at 3 and 6 months. Endografted animals were sacrificed at 1, 3, and 6 months after implantation; specimens from all animals were examined grossly and microscopically. Seven (35%) animals died within 24 hours of causes related to the technique; 1 animal developed paraplegia and was sacrificed on day 1. Three (25%) animals died of spontaneous aneurysm rupture at <10 days, and 6 received the stent-graft at 3 months. The macroporous cover did not prevent continued perfusion of the sac early after stent-graft deployment, but all aneurysms were excluded on the 1-month CT. Spontaneous AAA rupture occurred earlier and was not as frequent as previously described for this model. Implantation of the covered stent was feasible, but aneurysm exclusion was not immediate.