Operative Interventions
Off-pump coronary artery bypass operations for both cohorts were followed the standard care and processes of Hua Shan Hospital. In brief, after general anesthesia and well prepared mechanical circulatory support (both intra-aortic balloon pumps and extra-corporal circulation units), patients were performed conventional median sternotomy incision with harvesting of the left internal thoracic artery. Right internal mammary artery and/or radial artery and saphenous vein graft was performed as needed. Heparin was given at a low dose of 1 mg/kg to achieve a target activated clotting time (ACT) of at least 280s before ligation of the distal internal thoracic artery. The strategy of grafts was decided after the pericardium opened and the size of target vessels and heart assessed. Temporary stabilization of the target vessel achieved by an Octopus tissue stabilizer (Medtronic, Inc., Minneapolis, MN, USA) and if necessary supported with a deep pericardial traction suture. Intraluminal shunts (ClearView Intracoronary Shunt; Medtronic) and a blower mister (Guidant, Indianapolis, IN, USA) with carbon dioxide and warm isotonic sodium chloride were used to remove blood from the sites of arteriotomy and obtain a clear surgical field. An appropriately sized intra-coronary shunt was placed to maintain perfusion of the dependent myocardium and distal anastomosis performed using 7-0 polypropylene. Proximal anastomosis was done, if needed, using a partial occluding vascular clamp on the ascending aorta, an aortomoy punch and 5-0 polypropylene. Ultrasounds were routinely used to measure the patency and the flow of anastomosed grafts.