Human umbilical artery for microvascular grafting. Experimental study in the rat.

As microvascular surgery has developed, the necessity for smaller arterial prostheses of less than 2 mm in internal diameter (ID) has increased markedly. Glutaraldehyde-stabilized human umbilical arteries with 1.5 to 2.0 mm ID are smaller than any other graft material currently available. This study was designed to determine whether this graft material has potential clinical application for microanastomosis. Twenty male albino rats, each weighing 400 to 500 gm, were used in this study. The abdominal aorta was exposed and a 3- to 4-mm segment was resected. A 10-mm interposition graft of glutaraldehyde-stabilized human umbilical artery was implanted by end-to-end anastomosis. The patency of the grafts was determined by repeated operative exploration at intervals of 1 week, and 1, 3, 9, and 12 months. Two grafts were found to be occluded each time at the 1-, 3-, and 9-month explorations. At each exploration time, five rats were sacrificed and histopathological studies conducted. All five remaining grafts were patent at 12 months. There was no evidence of endothelial proliferation on the luminal surface of the patent grafts as determined by scanning electron microscopy. The luminal surface and underlying region consisted of an amorphous proteinaceous-like material. Significant degeneration of the vessel wall was noted in all grafts surviving over 9 months. Central necrosis surrounded by a chronic inflammatory process that extended to and included the adventitia was observed in the occluded grafts. While the patency demonstrated was good, the tissue changes noted in the walls of the grafts indicate that further study is necessary before this material can be used as a graft in humans.