Science Fair Project Encyclopedia
Coronary artery bypass surgery
A coronary artery bypass graft (CABG) or heart bypass is a surgical procedure performed in patients with coronary artery disease (see atherosclerosis) for the relief of angina and possible improved heart muscle function. Veins or arteries from elsewhere in the patient's body are grafted from the aorta to the coronary arteries, bypassing coronary artery narrowings caused by atherosclerosis and improving the blood supply to the myocardium (heart muscle).
First, the sternum is cut down the middle with a special bone saw and the chest opened (a procedure known as "cracking the chest" or a median sternotomy). Depending on a number of factors, the surgeon may decide to place the patient on cardiopulmonary bypass ("on-pump") or use suction-stabilizing devices to hold the heart still while sewing the anastamoses ("off-pump"). Blood vessels are harvested from elsewhere in the body for grafting. Sometimes artery end branches supplying tissues near the heart are rerouted to create the bypass.
Typically, the saphenous vein from the leg and the left internal mammary artery (LIMA ) are used for the bypass. Veins used either have their valves removed or are turned around so that the valves in them do not occlude blood flow in the graft. LIMA grafts are longer-lasting than vein grafts, both because the artery is more robust than a vein and because, being already connected to the aorta, the LIMA need only be grafted at one end. For this reason, the LIMA is usually grafted to the left anterior descending artery (LAD), which supplies the left ventricle, the part of the heart that pumps oxygenated blood around the body. Alternatively, an artery such as the radial artery from the arm, may be used in place of a vein. This is believed to prolong the life of the grafts but this has yet to be proven.
Prognosis following CABG depends on a variety of factors, but successful grafts typically last around 10-15 years.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details