Study Of The Efficacy Of Extracellular Matrix Arterial Interposition Grafts In A Sheep (Ovis aries) Model

Abstract : Objective: This study evaluated the long term performance of small intestine sub mucosa carotid artery grafts in sheep. Methods: Twelve sheep had both carotid arteries removed. Grafts were created by tubularizing extracellular matrix sheets with staples and anastomosed end-to-end. Groups of animals were survived for nine and twelve months. Results: 4 of 12 animals succumbed within weeks of the procedure due to failure of an anastomosis. Among 8 sheep, 11 of 16 grafts were patent. The remaining 5 grafts were occluded by organized thrombi. All of the patent grafts were aneurysmal with mid-graft diameters 3.1-fold greater than adjacent native carotid arteries. Ten of 11 patent grafts had ante mortem thrombi. Four of 11 appeared to have delaminating graft material. Degenerating material was visible in 5 of 11 grafts. Mononuclear cell infiltration was present in various amounts, forming lymphoid follicles in some grafts. Immunohistochemical staining of endothelial cells for vonWillebrand factor was only positive in 2 of 11 grafts. Conclusion: The tubularized stapled grafts were problematic, resulting in thrombus formation in nearly every graft. The extracellular matrix tended to be unincorporated and delaminating or degenerating in many cases. Overall, we cannot recommend tubularized extracellular matrix interposition grafts in a sheep model.