Coronary bypass surgery
What is Coronary bypass surgery?
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.
The obstruction being bypassed is due to arteriosclerosis, atherosclerosis, or both. Arteriosclerosis is characterized by thickening, loss of elasticity, and calcification of the arterial wall, most often resulting in a generalized narrowing in the affected coronary artery. Atherosclerosis is characterized by yellowish plaques of cholesterol, lipids, and cellular debris deposited into the inner layer of the wall of a large or medium-sized coronary artery, most often resulting in a focal partial obstruction in the affected artery, Each can limit blood flow if it causes a cross-sectional narrowing of at least 50%.