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Continuing investigations of vascular graft materials suggest that unacceptable graft complications continue and that the ideal graft material has not yet been found. We have developed and tested a biologic vascular graft material, small intestine submucosa (SIS), in normal dogs. This material, when used as an autograft, allograft, or xenograft has demonstrated biocompatibility and high patency rates in aorta, carotid and femoral arteries, and superior vena cava locations. The grafts are completely endothelialized at 28 days post-implantation. At 90 days, the grafts are histologically similar to normal arteries and veins and contain a smooth muscle media and a dense fibrous connective tissue adventitia. Follow-up periods of up to 5 years found no evidence of infection, intimal hyperplasia, or aneurysmal dilation. One infection-challenge study suggested that SIS may be infection resistant, possibly because of early capillary penetration of the SIS (2 to 4 days after implantation) and delivery of body defenses to the local site. We conclude that SIS is a suitable blood interface material and is worthy of continued investigation. It may serve as a structural framework for the application of tissue engineering technologies in the development of the elusive ideal vascular graft material.

Autogenous saphenous vein, human umbilical vein, modified bovine collagen, Dacron, and PTFE have been used as small-diameter arterial grafts with moderate success. We tested autogenous small intestine submucosa as a small-diameter arterial graft in both a carotid and femoral artery (mean ID 4.3 mm) of 18 dogs (total of 36 grafts). All dogs received aspirin and warfarin sodium for the first 8 weeks after surgery. Graft patency was evaluated by Doppler ultrasound techniques and angiography. Two grafts ruptured and 5 grafts occluded by 21 days after surgery. One graft became occluded at 14 weeks. Fifteen dogs were sacrificed at periodic intervals until 48 weeks after surgery. Patent grafts had no evidence of infection, propagating thrombus, or intimal hyperplasia. Graft aneurysmal dilation occurred in 4 grafts (11%). The grafts were composed of a dense organized collagenous connective tissue with no evidence of endothelial cell growth on the smooth luminal surface. Three dogs are alive at 76 to 82 weeks after surgery. Overall, graft patency was 75%. Graft patency after cessation of anticoagulation therapy was 92.3% (12 of 13 grafts). We conclude that autogenous small intestinal submucosa can be used as a small-diameter arterial graft in the dog and is worthy of further investigation.

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