Coronary Artery Bypass Surgery
Coronary artery bypass grafting is one of the most common operations
performed in the United States, with over 150,000 procedures performed
annually. It is the most common operation performed by heart surgeons.
When plaque builds up in the coronary arteries, the flow of blood to
the heart muscle is slowed or stopped. When the heart muscle can not
get enough oxygen and nutrients carried by the blood, angina or pain
results. In extreme cases, when there is no blood flow to the muscle,
a heart attack occurs. The symptoms of a heart attack are variable,
ranging from no symptoms to chest pain to sudden death. In order to
prevent or limit these symptoms, heart surgeons can perform Coronary
Artery Bypass Grafting (CABG) to reroute blood flow beyond the areas
of blockage. The typical CABG operation uses arteries from behind the
breast bone and veins from the legs to use as a conduits for the bypass
procedure. Cardiac catheterization performed by a cardiologist provides
the surgeon a road map to properly place the bypasses. Click here
to view a cardiac cateterization movie.
After a patient is asleep,
the vein from the leg is removed by the surgeon or surgical assistant
to use for bypass grafting. The length of vein removed depends on the
number of vein segments required for the bypasses. The vein can safely
be removed from the leg because there are many other veins in the leg
to take over the function of the removed vein. Often the leg will swell
for a few weeks until the other veins enlarge to take over the return
of blood from the leg. 
At the same time that the vein is taken out of the leg, the surgeon
opens the chest, usually through an incision in the breast bone. Once
the breast bone has been opened, the surgeon prepares an artery which
lies just under the ribs for use as a bypass graft. This artery is called
the Internal Mammary or Internal Thoracic Artery. Once all of the conduits
have been prepared, the patient is placed on the cardiopulmonary bypass
machine, otherwise known as the heart-lung machine. This machine takes
over the function of the heart (pumping blood to all the organs in the
body) and lungs (allowing oxygen to enter the blood and carbon dioxide
to leave the blood). This allows the surgeon to work on the heart while
it is motionless and bloodless in order to sew bypass grafts to the
coronary arteries downstream from the blockages. In some cases, the
heart-lung machine is not required. Special devices are then used to
immobilize a small area of the heart so the surgeon can sew the grafts
onto the coronary arteries.
Once the conduits are sewn to the coronary arteries, the other ends
of the veins are sewn to the large artery arising from the heart, the
aorta. This allows blood to flow from the aorta (which is upstream from
the blockage), through the vein graft, and then into the coronary artery
downstream from the blockage. 
The
final image is that of the completed coronary artery bypass operation
showing two saphenous vein grafts and one internal mammary artery graft.