OBJECTIVE: We evaluated the effect of close contact between the stent and the graft on the induction of endothelial covering on the stent graft placed over an aneurysm. MATERIALS AND METHODS: Saccular abdominal aortic aneurysms were made with Dacron patch in eight dogs. The stent graft consisted of an inner stent, a expanded polytetrafluoroethylene graft, and an outer stent. After sacrificing the animals, the aortas with an embedded stent graft were excised. The aortas were inspected grossly and evaluated microscopically. RESULTS: The animals were sacrificed at two (n = 3), six (n = 3), and eight months (n = 2) after endovascular repair. In two dogs, the aortic lumen was occluded at two months after the placement. On gross inspection of specimens from the other six dogs with a patent aortic lumen, stent grafts placed over the normal aortic wall were covered by glossy white neointima, whereas, stent grafts placed over the aneurysmal aortic wall were covered by brownish neointima. On microscopic inspection, stent grafts placed over the normal aortic wall were covered by thin neointima (0.27 +/- 0.05 mm, mean +/- standard deviation) with an endothelial layer, and stent grafts placed over the aneurysmal aortic wall were covered by thick neointima (0.62 +/- 0.17 mm) without any endothelial lining. Transgraft cell migration at the normal aortic wall was more active than that at the aneurysmal aortic wall. CONCLUSION: Close contact between the stent and the graft, which was achieved with stent grafts with endo-exo-skeleton, could not enhance endothelial covering on the stent graft placed over the aneurysms.
Animals ; Aortic Aneurysm, Abdominal/pathology/*therapy ; Blood Vessel Prosthesis Implantation ; Disease Models, Animal ; Dogs ; Endothelium, Vascular/cytology/pathology ; *Stents ; Tomography, X-Ray Computed

Primary aortoenteric fistula (PAEF) is a rare disease with a high mortality rate due to massive hemorrhaging and diagnostic difficulties. Although hemorrhagic regions can be identified by endoscopy, it is difficult to diagnose PAEF by this method. If PAEF is suspected, endoscopic procedure should be terminated and abdominal CT should be performed. Overlooking the herald bleeding of PAEF can lead to massive bleeding and death. An 85-year-old previously healthy male presented with a complaint of melena. Gastrointestinal endoscopy identified a hemorrhagic site in the third portion of the duodenum and endoscopic hemostasis was performed. However, during the procedure, it became apparent that the hemorrhage was probably not the result of a simple duodenal ulceration and abdominal CT was performed immediately. An aortic aneurysm connected to the duodenum was identified, confirming the diagnosis of PAEF. However, the patient died of massive hemorrhaging before an operation could be performed.
Aged, 80 and over ; Aortic Aneurysm, Abdominal/*diagnosis/pathology ; Diagnosis, Differential ; Endoscopy, Gastrointestinal ; Fibrin Tissue Adhesive/therapeutic use ; Fistula/*diagnosis/pathology ; Gastrointestinal Hemorrhage/diagnosis/therapy ; Humans ; Male ; Tomography, X-Ray Computed