Like conventional bypass surgery, off-pump coronary artery bypass surgery (OPCAB) is an operation that treats patients with blocked coronary arteries. The coronary arteries lie on the surface of the heart and supply the heart muscle with oxygen-rich blood. They may become clogged with deposits of plaque, thus reducing the amount of oxygen-rich blood that can flow to the heart. By dramatically improving the flow of oxygen-rich blood to the heart (a process called revascularization), an off-pump bypass greatly reduces the risk of  angina and heart attack.

Off-pump bypass involves the same two procedures that are performed during traditional bypass surgery. In the first, the surgeon removes (harvests) one of the patient’s blood vessels – usually either the saphenous vein in the leg or the mammary artery. In the second procedure, the surgeon uses the blood vessel to create a detour (bypass graft) around the blockages in the coronary arteries.

However, off-pump bypass differs from traditional bypass surgery because the surgeon is able to operate on the heart while it is still beating, rather than stopping the heart and using the heart-lung machine. Thus, off-pump surgery is sometimes nicknamed “beating heart” surgery. By forgoing use of the heart-lung machine, the risk of complications associated with the machine is avoided. These complications include depression and/or mood swings that are common after use of the heart-lung machine. Other side effects of the machine include possible stroke and memory problems after the surgery (post-pump syndrome). In addition, bleeding is greatly reduced, so patients are less likely to need a blood transfusion.

Off-pump surgery may be performed with a traditional chest incision, or by using newer minimally invasive techniques. About 25 percent of the bypass operations performed in the United States are off-pump surgeries using a traditional chest incision.

During this procedure, the surgeon makes an incision in the chest, cutting through the breastbone (sternum), after harvesting the vessel for the bypass graft. The two halves of the breastbone are divided (median sternotomy), and a retractor will be used to pull back the two halves of the breastbone to give the surgeon plenty of room to work. The ribs are not divided, thereby reducing discomfort during recovery.

The surgeon will then use certain heart stabilizers and positioners to keep the targeted region of the heart virtually motionless while working on a particular coronary artery. The heart maintains its own rhythm throughout the procedure.

The next step is to sew the bypass graft into place in the chest. For each blockage, the surgeon will graft one end of the harvested vein to a larger artery (e.g., the aorta) and will sew the other end into place beyond the blockage in the coronary artery. Once this is finished, blood can flow freely through the bypass graft, around the blockage and into the coronary artery, restoring healthy blood flow to the heart muscle.

When the surgeon is satisfied that complete blood circulation has been restored to the heart, the surgical site will be carefully closed layer by layer. The sternum will be closed, usually with wire, and the surface incision will be closed with staples or sutures, depending on the surgeon’s preference. The entire surgery takes approximately two to five hours. Recovery from OPCAB is similar to traditional bypass surgery because of the surgical incision.

Because off-pump bypass surgery is still a new procedure, studies on the long-term effect of OPCAB are still emerging. It appears that the results of OPCAB are similar to conventional surgery, and it is effective in treating patients with single- or multi-vessel coronary artery disease. OPCAB may also be recommended for patients who cannot tolerate having their heart stopped, including those who are elderly with widespread disease.  Patients who may undergo bypass operation should discuss all the possible benefits and disadvantages of each procedure with their physician.

Off pump surgery is not suitable for patients who, in addition to the coronary bypass, require surgery to repair/replace their heart valves or to close a defect within the heart.