Coronary artery bypass surgery is a type of surgery that relieves chest pain, caused by lack of blood flow, and reduces the risk of death from heart disease. It is also known as coronary artery bypass graft (CABG, pronounced "cabbage") surgery, and known by doctors as heart bypass or bypass surgery. In this surgery, blood vessels from elsewhere in the patient's body are added to the heart vessels to go around blood vessels blocked by fat and get more blood into the heart so it can keep running. This surgery usually happens with the heart stopped, which makes machines that act as lungs and heart needed. However, it is possible to have the surgery with the heart still pumping, called "off-pump" surgery. 