Intima–Adventitia Apposition in End-to-Side Arterial Anastomosis: An Experimental Study in the Pig

Background. To prevent ischemic complications during coronary bypass grafting on the beating heart, a nonocclusive distal anastomosis technique is needed. One recently developed nonocclusive technique requires apposition of the intima of the graft to the adventitia of the recipient artery, in contrast to current surgical practice, which dictates apposition of both intimas. Methods. To compare the sole effect of intima–adventitia apposition (n = 18) versus traditional intima–intima apposition (n = 18), we investigated radiolabeled platelet deposition and histomorphologic aspects of vascular wall healing quantitatively in a porcine carotid artery bypass graft model. Both groups were evaluated at 2 hours, 2 days, or 4 weeks. Results. Within the first 2 hours, 3 of 6 pigs with intima–adventitia apposition exhibited cyclic flow reductions as a result of massive mural thrombosis. After intima–adventitia apposition, the number of deposited platelets was significantly higher compared with intima–intima apposition, 147.1 ± 73.0 × 106 and 4.6 ± 1.0 × 106 platelets/cm2 (mean ± standard error of the mean), respectively (p = 0.03). At 2 days, the suture line was covered with small mural thrombi, whereas no thrombi were found after intima–intima apposition. At 4 weeks, intimal hyperplasia at heel and toe was not significantly different from that with intima–intima apposition. Conclusions. Despite thrombotic phenomena in the early phase, intima–adventitia apposition yielded a patent anastomosis with a small intimal hyperplasia response.