A coronary artery bypass surgery is also known as coronary artery bypass grafting surgery or CABG. If the supply of oxygen-rich blood to the heart gets cut off due to blocks in one or more coronary arteries, CABG is performed to bypass the blocked artery or arteries and restore the normal flow of blood to the heart. Surgeons will use grafts to bypass blocked arteries and restore blood flow to the heart. The graft is a healthy blood vessel taken from arteries or veins in the chest, leg or arm, and it is used to create a new pathway to carry the blood to the heart.