Surgical techniques
All patients underwent OPCABG operation were through a standard median-sternotomy with the left internal mammary artery (LIMA) harvested. Standard anesthetic induction was performed with intravenous propofol or dexmedetomidine, fentanyl, and vecuronium, which was followed by a standard monitoring of arterial catheterization and Swan-Ganz catheter. Heparin was administered to maintain adequate heparinization (ACT, activated clotting time>250seconds). Commercially available mechanical stabilization devices such as the Octopus 2 were used to stabilize the coronary targets on the beating heart and pericardial traction sutures were used where appropriate. Retrograde bleeding was controlled with a sterile, humidified carbon dioxide blower. Distal anastomoses were constructed with a continuous running 7-0 polypropylene suture and proximal anastomoses 6-0 polypropylene suture1,31-35.