Heart bypass

Coronary artery bypass surgery
Intervention
Early in a coronary artery bypass operation, during vein harvesting from the legs (left of image) and the establishment of cardiopulmonary bypass by placement of an aortic cannula (bottom of image). The perfusionist and heart-lung machine are on the upper right. The patient's head (not seen) is at the bottom.
ICD-10-PCS	021209W
ICD-9-CM	36.1
MeSH	D001026
MedlinePlus	002946
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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 to restore normal blood flow to an obstructed coronary artery.

There are two main approaches. In one, the left internal thoracic artery (internal mammary artery) is diverted to the left anterior descending branch of the left coronary artery. In the other, a great saphenous vein is removed from a leg; one end is attached to the aorta or one of its major branches, and the other end is attached to the obstructed artery immediately after the obstruction to restore blood flow.

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.

Arteries usually have a 50% to 99% obstruction. 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%.