The heart is a beating muscle that pumps oxygen-rich blood to the body's cells. The coronary arteries supply the heart itself with the blood it needs to function effectively. Coronary means, "crown". The arteries crown or surround the heart muscles.

If the coronary arteries become narrowed or blocked due to the fatty buildup called plaque, the flow of blood to certain parts of the heart can decrease or stop. When this happens, it causes the cells in that region to die, and leaves the heart without the proper amount of blood it needs to function.

Coronary artery bypass surgery, also called CABG, is commonly performed to re-route the flow of blood around the blockage. In traditional bypass surgery, the chest is opened and the heart temporarily stopped to allow the surgeon to perform the bypass.

Traditional bypass surgery requires the use of a heart-lung machine, which infuses the patient's blood with oxygen and pumps it back into the body during the proceedure. In some patients, however, surgeons may perform bypass operations without stopping the heart and without using a heart-lung machine. These procedures are called "beating heart" operations.

In both traditional and beating heart procedures, the surgeon attaches a blood vessel from the aorta to a point below the blocked artery. The saphenous vein in the leg is often used for the bypass. In the past, an incision running almost the length of the leg was required to harvest this blood vessel. Today, a technique called endoscopic vein harvesting enables the surgeon to harvest the vessel through one to three small incisions.

Medical advances, such as beating heart surgery and endoscopic vein harvesting, are making bypass surgery a less traumatic and less painful proceedure for thousands of people every year.