Coronary artery bypass surgery, performed to relieve angina and reduce the risk of death from coronary artery disease. Arteries or veins from elsewhere in the patient's body are grafted to the coronary arteries to bypass atherosclerotic narrowings and improve the blood supply to the coronary circulation supplying the myocardium (heart muscle). Possibilities include direct end-to-end, side-to-side and end-to-side anastomosis of the vessels
