EXPERIMENTAL EVALUATION OF SMALL-INTESTINAL SUBMUCOSA AS A MICROVASCULAR GRAFT MATERIAL

The evaluation of porcine small intestine submucosa (SIS) in a microsu rgical model was conducted using an interpositional graft in the rat f emoral artery. The SIS grafts were fabricated from processed porcine m aterial that was wrapped around a glass tube and oversewn longitudinal ly to produce a tubular structure. Of the 42 animals studied, 7 receiv ed grafts of untreated SIS (group I), 7 of grafts were presoaked (PSH) in heparin (Group II), 7 animals were treated with systemic heparin p rior to implantation of PSH-SIS (group III), 7 animals received SIS gr afts crosslinked to heparin (group IV), 7 animals received SIS grafts crosslinked to urokinase (group V), and 7 animals received untreated a utologous epigastric vein grafts (group VI). Patency was assessed post operatively and selected grafts were evaluated by histology. All SIS g rafts failed to maintain patency beyond the first postoperative hour. Histologic examination of the thrombosed graft surfaces revealed a smo oth luminal surface with a thick layer of attached fibrin and platelet s with a central occluding thrombus. The thickness of the induced fibr in layer appears to narrow intraluminal space significantly at the mic rovascular level. While having excellent success at vessel diameters g reater than 3 mm, and in a variety of nonporcine animal models without xenographic rejection, SIS in this model was thrombogenic despite a f avorable surface morphology as demonstrated by SEM. Even with use of h eparin and urokinase SIS graft thrombosis occurred.