Oﬀ-Pump Coronary Artery Bypass Surgery
The development of advanced epicardial stabiliz-ing devices, such as the Octopus (Figure 22–16), has facilitated coronary artery bypass grafting with-out the use of CPB, also known as off-pump coro-nary artery bypass (OPCAB). This type of retractor uses suction to stabilize and lift the anastomotic site rather than compress it down, which allows for
greater hemodynamic stability. Full (CPB) dose hep-arinization is usually given and the CPB machine is usually immediately available if needed.
Intravenous fluid loading together with inter-mittent or continuous infusion of a vasopressor may be necessary while the distal anastomoses are sewn. In contrast, a vasodilator may be required to reduce the systolic pressure to 90–100 mm Hg during partial clamping of the aorta for the proximal anastomosis. Intravenous nitroglycerin is often used because of its ability to ameliorate myocardial ischemia.
Although OPCAB was initially proposed for “simple” one- or two-vessel bypass grafting in patients with good left ventricular function, careful application of the technique has allowed it to be used routinely for multigraft surgery, redo operations, and patients with compromised left ventricular func-tion (and it may be the “sicker” patients who benefit most from avoidance of CPB). Some surgeons use an intraluminal shunt to maintain coronary blood flow during sewing of distal anastomoses. Myocardial preconditioning, brief periods of coronary occlusion prior to the more prolonged occlusion, reduce areas of necrosis following prolonged periods of isch-emia in animal studies, but the technique has found limited use in OPCAB. On the other hand, volatile anesthetic agents and morphine provide myocardial protection during prolonged periods of ischemia. Maintenance of anesthesia with a volatile agent may therefore be desirable. When the surgeon is skill-ful, long-term graft patency may be comparable to procedures done with CPB. Patients with extensive coronary disease, particularly those with poor target vessels, may not be good candidates. OPCAB may decrease the incidence of postoperative neurological complications and the need for transfusion relative to conventional coronary bypass with CPB.