Question: How does a surgeon decide whether to use veins from the legs or arteries from the chest to do bypass surgery?
Answer: When we do a bypass operation, we have several options for conduit where the vessels that we'll use for the bypass graft. We like to use the internal mammary artery, or internal thoracic artery, which is on the left side of the sternum. And the reason that we like to use that artery is that it stays open longer than veins, in general. For that reason, we use the internal mammary artery or the internal thoracic artery to bypass the most important vessel on the heart; that's the left anterior descending artery, the one that goes down the front and supplies about two-thirds of the left ventricle. The left ventricle is the main pumping chamber of the heart.
Internal mammary artery graft to the left anterior descending to that most important vessel in the front of the heart has about a 95 percent chance of being open ten years after your bypass operation. And it's well recognized, it's proven that an internal mammary graft to the left anterior descending can actually improve your chances of long-term survival. So in today's day and age, about 95 percent of bypass operations are done, including a left internal mammary artery to the left anterior descending.
Now, depending on what disease you have and how many bypasses you need, we may need other bypass grafts. For candidates that are good candidates for using the other internal mammary artery, we like to use that for the same reason: arteries stay open longer than veins. Although some patients are not good candidates for using the right internal mammary artery because they may have diabetes, they may be smokers that have lung disease, they may have underlying emphysema, or they may be overweight -- in which case the stress on the sternum is greater -- and there may be healing problems if we use both internal mammary arteries. In those instances we use some vein from the leg.
Now there are other instances where we may not want to use vein from the leg, where people have peripheral vascular disease that makes healing of the leg wound harder, and in those cases we'll actually prefer to use both internal mammary arteries.
So in each case, it's a selection process that has to be made tailored to the patient's specific characteristics, whether we use veins, arteries, and how much of each we use.