The axillocoronary bypass: Blood flow and short-term graft histology in a porcine model

Background Bypass grafts arising from the axillary artery may be indicated for complications during minimally invasive direct coronary artery bypass grafting, for redo operations and for management of a severely atherosclerotic ascending aorta. As basic data research on this technique is scanty, we investigated intraoperative function and postoperative morphology of axillocoronary bypass grafts in a porcine model. Methods. Thirteen German domestic pigs received an axillocoronary vein graft (Group I, n=7) or an aortocoronary vein graft (Group II, n=6) to the left anterior descending artery. In Group I the proximal anastomosis was performed to the left axillary artery, and after partial rib resection the graft was brought transpleurally to the target vessel. In both groups the coronary anastomosis was carried out on the beating heart without cardiopulmonary bypass. Graft flow was measured using transit time ultrasonic flow probes. Results. Intraoperatively all grafts showed a typical diastolic flow profile. Stable graft flow was lower in axillocoronary bypass grafts: 47 (30-60 mL/min) in Group I and 65 (35-126 mL/min) in Group II (p=0.005). Flow given as percentage of cardiac output, however, did not differ between the two grafts: 0.9 (0.6-1.2%) in Group I and 1.2 (0.8-2.4%) in Group II (p-NS). At day 4 after surgery there was no clear histologic predilection site for microtrauma and early degenerative changes in the axillocoronary graft. Conclusions. Axillocoronary bypass flow compares well with flow in the aortocoronary graft. Micro trauma after implantation and early degenerative changes in the axillocoronary vein bypass are not particularly impacted by the thoracic entry site.