Coronary artery bypass graft surgery (CABG) is a procedure used to treat coronary artery disease. Coronary artery disease (CAD) is the narrowing of the coronary arteries – the blood vessels that supply oxygen and nutrients to the heart muscle. CAD is caused by a build-up of fatty material within the walls of the arteries. This build-up narrows the inside of the arteries, limiting the supply of oxygen-rich blood to the heart muscle.
One way to treat the blocked or narrowed arteries is to bypass the blocked portion of the coronary artery with a piece of a healthy blood vessel from elsewhere in the body. Blood vessels, or grafts, used for the bypass procedure may be pieces of a vein from the legs or an artery in the chest. An artery from the wrist may also be used. One end of the graft is attached above the blockage and the other end is attached below the blockage. Blood is routed around, or bypasses, the blockage by going through the new graft to reach the heart muscle. This is called coronary artery bypass surgery.
Traditionally, to bypass the blocked coronary artery, a large incision is made in the chest and the heart is temporarily stopped so that the surgeon can perform the delicate procedure. To open the chest, the breastbone (sternum) is cut in half and spread apart. Once the heart is exposed, tubes are inserted into the heart so that the blood can be pumped through the body by a cardiopulmonary bypass machine (heart-lung machine). The bypass machine is necessary to pump blood while the heart is stopped and kept still in order for the surgeon to perform the bypass operation.
While the traditional "open heart" procedure is still commonly done and often preferred in many situations, less invasive techniques have been developed to bypass blocked coronary arteries. "Off-pump" procedures, in which the heart does not have to be stopped, were developed in the 1990's. Other minimally invasive procedures, such as keyhole surgery (performed through very small incisions) and robotic procedures (performed with the aid of a moving mechanical device), may be used.