Histology and electron microscopy of explanted bifurcated endovascular aortic grafts: Evidence of early incorporation and healing

Purpose: To report an examination of explanted bifurcated endovascular aort ic grafts for histologic evidence of early healing and incorporation. Method: Two bifurcated endovascular aortic grafts composed of polycarbonate urethane and Elgiloy wire were explanted 42 and 21 days after successful e ndovascular exclusion of abdominal aortic aneurysms. Both patients expired from causes unrelated to endograft deployment. The explanted devices were e xamined using immunohistochemical analysis and electron microscopy. Results: On explantation, both grafts appeared to have excluded the aneurys m with no evidence of endoleak, graft migration, or thrombosis. Histologica l examination showed numerous inflammatory cells and good ingrowth of tissu e into the proximal 2 cm of the graft. Collagen and smooth muscle cells wer e evident in the proximal portion of the graft with only collagen in the di stal segments. Neointimal formation was seen within the proximal 2 cm also, but not at the distal segments. Macrophages were present in the graft. Sca nning electron microscopy showed an extensive matrix of fibers that most li kely represented collagen. Conclusions: Bifurcated endovascular aortic grafts show inflammatory and mi ld foreign body reactions, collagen formation, and intimal ingrowth during healing. These findings are similar to some of the healing properties repor ted for sutured grafts, as well as other endovascular grafts.