Evaluation of a porcine internal mammary artery (No-React II) as a small-diameter conduit

Background. The patency of biologic small-diameter vascular grafts in the a ortocoronary position is still unsatisfactory. Most of the studies suggest that xeno-grafts are to be avoided as an aortocoronary bypass. Methods. The porcine internal mammary artery treated by the No-React II pro cedure was developed for use as an alternative coronary artery bypass condu it. The attempt of this study was to evaluate the patency and histologic ch anges of the porcine internal mammary artery in animals. Five calves underw ent coronary artery bypass grafting with a porcine internal mammary artery graft to the right coronary artery. After euthanasia of the animals 103 day s later, the samples of these grafts were studied morphologically for paten cy, structural changes, calcifications, acid inflammatory and immunologic r esponse. Results. One animal died during the procedure as result of acute thrombosis of the porcine internal mammary artery graft. In the other 4 animals all g rafts became occluded. In the histologic sections of the grafts we noted mu ltiple calcifications and a host-graft immunologic reaction (severe chronic rejection). Conclusions. The present study demonstrates a very poor experience with the porcine internal mammary artery (No-React II) conduit. We do not recommend this prosthesis for clinical use in humans. (C) 1998 by The Society of Tho racic Surgeons.