Heart bypass or coronary artery bypass graft (CABG, pronounced cabbage) is a surgery that may become necessary when the arteries that supply blood and oxygen to the heart muscle become hardened and narrowed. This procedure treats blocked heart arteries by using arteries or veins from other parts of the body, called grafts, to create new passages for blood to flow to the heart muscle.

Heart bypass surgery is a relatively common procedure that requires expertise with the use of complex equipment; technical errors while using this equipment may lead to significant complications such as heart attack, stroke or death. Better processes of care in hospitals may reduce the risk of death (mortality) from heart bypass surgery.