Endoluminal treatment of ruptured abdominal aortic aneurysm with small intestinal submucosa sandwich endografts: A pilot study in sheep

Purpose: To evaluate efficacy of small intestinal submucosa (SIS) Sandwich endografts for the treatment of acute rupture of abdominal aortic aneurysms (AAA) and to explore the short-term reaction of the aorta to this material . Methods: In eight adult sheep, an infrarenal AAA was created transluminally by dilation of a short Palmaz stent. In six sheep, the aneurysm was then r uptured by overdilation of the stent with a large angioplasty balloon. Two sheep with AAAs that were not ruptured served as controls. A SIS Sandwich e ndograft, consisting of a Z stent frame with 5 bodies and covered inside an d out with SIS, was used to exclude the ruptured and non-ruptured AAAs. Fol low-up aortography was done immediately after the procedure and before sacr ifice at 4, 8, or 12 weeks. Autopsy and histologic studies followed. Results: Endograft placement was successful in all eight sheep. Both ruptur ed and non-ruptured AAAs were successfully excluded. Three animals with AAA rupture developed hind leg paralysis due to compromise of the arterial sup ply to the lower spinal cord and were sacrificed 1 day after the procedure. In five animals, three with rupture and two controls, follow-up aortograms revealed no aortic stenoses and no perigraft leaks: Gross and histologic s tudies revealed incorporation of the endografts into the aortic wall with r eplacement of SIS by dense neointima that was completely endothelialized in areas where the endograft was in direct contact with the aortic wall. In c entral portions of the endograft, in contact with the thrombosed aneurysm, endothelialization was incomplete even at 12 weeks. Conclusion: The SIS Sandwich endografts effectively excluded simple AAAs an d ruptured AAAs. They were rapidly incorporated into the aortic wall. A det ailed long-term study is warranted.