Coronary artery bypass surgery, also known as coronary artery bypass graft (CABG, pronounced "cabbage") surgery, and colloquially heart bypass or bypass surgery, is a surgical procedure consisting of either diverting the left internal thoracic artery (left internal mammary artery or "LIMA") to the left anterior descending (LAD) branch of the left main coronary artery; or a harvested great saphenous vein of the leg, attaching the proximal end to the aorta or one of its major branches, and the distal end to immediately beyond a partially obstructed coronary artery (the "target vessel") - usually a 50% to 99% obstruction. The purpose is to restore normal blood flow to that partially obstructed coronary artery. It is performed to relieve angina unsatisfactorily controlled by maximum tolerated anti-ischemic medication, prevent or relieve left ventricular dysfunction, and/or reduce the risk of death. It does not prevent heart attacks. This surgery is usually performed with the heart stopped, necessitating the usage of cardiopulmonary bypass; however, two alternative techniques are also available allowing CABG to be performed on a beating heart either without using the cardiopulmonary bypass deemed as "off-pump" surgery or performing beating surgery using partial assistance of the cardiopulmonary bypass called as "on-pump beating" surgery. The latter gathers the advantages of the on-pump stopped and off-pump while minimizing their respective side-effects.