Cardiac bypass surgery is an operation to restore the flow of blood through the arteries that supply blood to the heart, when a blockage or partial blockage occurs in these arteries.
The arteries that supply the heart muscle with oxygen and nutrients are known as the coronary arteries. The word "coronary" means a crown, and is the name given to these arteries that circle the heart like a crown. The narrowing of the arteries of the heart is known as coronary artery disease, which is the most common form of heart disease.
The operation, also known as a coronary artery bypass graft (CABG), involves rerouting the blood flow around the obstructed part of the artery. This is done by using a portion of a blood vessel taken from another part of the body, usually the leg or chest, and surgically attaching it across a severely narrowed or blocked coronary artery, thus "bypassing" the blockage. These "new" blood vessels carry blood around the obstruction, so that the blood supply to and from the heart is restored.
Coronary artery disease develops when one or more of the coronary arteries that supply the blood to the heart become narrower than they used to be, due to the buildup of cholesterol and other substances in the wall of the artery. This affects the blood flow to the heart muscle. Without an adequate blood supply, heart muscle tissue can be damaged.
Deposits of cholesterol and other fat-like substances can build up in the inner lining of these blood vessels and become coated with scar tissue, forming a cholesterol-rich bump in the blood vessel wall known as plaque. Plaque buildup narrows and hardens the blood vessel, a process called atherosclerosis, or hardening of the arteries.
Eventually these plaque deposits can build up to significantly reduce or block blood flow to the heart. A person may experience chest pain or discomfort from inadequate blood flow to the heart, especially during exercise when the heart needs more oxygen. This is known as angina.
For further information about angina, go to Angina.