Off-pump revascularization of the coronary arteries can be done through minimally invasive approaches or through a full sternotomy. When a full sternotomy is used as in off-pump coronary artery bypass surgery (OPCAB), the heart is lifted and manipulated using various support devices to permit the completion of multiple coronary bypass grafts. For the minimally invasive approach, a small thoracotomy is used and only the left internal mammary artery is generally grafted to the left anterior descending artery as in the minimally invasive direct coronary artery bypass (MIDCAB) technique. In either approach during "off-pump" bypass surgery the surgeon will occlude blood flow to the vessel being bypassed both proximally and distally using silastic snares and other occlusive devices. The surgical field is occasionally flooded with carbon dioxide to minimize entrainment of air into the coronary artery during surgical manipulation. Since the beating heart, when operated upon, presents the surgeon with a moving target there are various stabilization devices (Figure 13–1) commercially available, which relatively immobilize that region of the myocardium where the surgeon plans to create the bypass anastomoses. The surgeon must position the heart in such a manner that their access is suitable to complete the surgical repair. During positioning of the heart, venous return can be impaired leading to hemodynamic instability and hypotension. Often, however, once the heart is positioned in such a way that the graft can be placed, venous return becomes adequate and the heart pumps a suitable cardiac output to maintain the blood pressure even when lifted and retracted in the thorax. Frequently, the surgeon occludes the coronary artery to be bypassed for a brief period to determine the patient's response to vessel occlusion and to possibly provide ischemic preconditioning. Following this trial the surgeon reperfuses the vessel in the hope that through ischemia preconditioning the myocardium supplied by that vessel will be more resilient to ischemia. The vessel is reoccluded and the anastomosis completed. During this period, the coronary artery being bypassed is ligated, and, thus, the myocardium dependent on that vessel's flow distribution may become ischemic. Of course, since the vessel requires bypass in the first place there may have been little flow from it to the myocardium, thereby minimizing the effect of vessel occlusion. However, if that vessel provides sufficient flow to an area of viable heart muscle not supplied by collaterals, the heart may become rapidly ischemic during surgical repair. Systemic heparin (a dose of 100-300 units/kg but typically lower than the doses used for CPB, usually to a target activated clotting time of 250-300 s) is administered before vessel occlusion. Should efforts to support the circulation be inadequate during "off-pump" bypass the surgical team should be prepared for full heparinization and conversion to an on-pump approach. The CPB pump should be fully primed and on standby with the perfusionist in attendance for the case.