Aorta-coronary bypass grafting with heparinized vascular grafts in dogs: A preliminary study

Abstract

At present, only the autogenous saphenous vein is acceptable in aorta-coronary bypass grafting. We developed a small-caliber vascular graft and evaluated the potential application for aorta-coronary bypass grafting. Canine carotid arteries were cross-linked with polyepoxy compounds, such as polyglycerol polyglycidyl ether, which is a new cross-linking reagent, and then heparinized by our own method. The polyepoxy compound-cross-linked graft can keep the natural vessel compliance and is stronger than the glutaraldehyde-cross-linked graft; thus, it provides excellent suturability and compliance match. Heparin was gradually released from the graft wall, and thrombus formation was completely prevented during the period before development of the endothelial lining. As a pilot study, the grafts, 2 to 3 mm in internal diameter and 5 to 7 cm in length, were evaluated as bilateral carotid replacements in five dogs. All grafts were patent at intervals of 14 to 177 days. Histologic examinations showed excellent antithrombogenic and healing characteristics, although the endothelialization was delayed by heparin, which inhibits cell adhesion and fibrin deposition. The 3 mm internal diameter graft was evaluated as an aorta-coronary bypass grafting model in eight dogs. Flow within grafts to the right coronary artery ranged from 25 to 35 ml/min, and flow in the circumflex or left anterior descending grafts ranged from 75 to 100 ml/min. Cineangiography was performed to confirm graft patency. Three dogs died of viral infection and one was killed. At necropsy, the grafts remained patent without thrombi along the graft length. Four dogs were allowed to survive for long-term evaluation. All grafts were patent at time intervals to 21 to 113 days with 100% patency. These results led us to conclude that our newly developed small-caliber vascular graft shows great promise in application for aorta-coronary bypass grafting.