The aorta is the main artery which carries blood from the heart. It gives off branch arteries which supply blood to the brain, arms, legs, kidneys, intestines, etc. After leaving the heart, the aorta passes backward and then down next to the spine. At the level of the belly button, it divides into two branches to the legs.
In some people, a combination of degeneration of the wall of the aorta (atherosclerosis) and high blood pressure produces dilation and thinning of the aortic wall. This bulging section of the aorta is called an aneurysm. Usually it occurs in the aorta below the arteries to the kidneys and above the branches to the legs.
No one knows exactly why some people get aneurysms.
They are more common in men, and are more likely if there is high blood pressure and other signs of atherosclerosis (hardening of the arteries). Aneurysms also tend to run in families; if you have one, you should make sure that your brothers, sisters, and children are checked too. Two things may help to prevent growth of an aneurysm: good blood pressure control, and stopping smoking.
Aneurysms tend to grow as the blood pressure stretches the wall of the aorta. The danger of an aneurysm is that it may rupture without warning. If the aneurysm ruptures, there is massive bleeding internally, and this is almost always fatal. The bigger the aneurysm, the more likely it is to bleed. Aneurysms which are growing are more likely to bleed than those which stay the same size.
Once an aneurysm has reached a dangerous size (about twice the normal size of the aorta), there is about a one-in-twenty chance per year that it will bleed. If it grows to three times normal size (about three inches), there is about a one-in-two chance! The only way to prevent rupture is to repair the aorta with an artificial graft. At this time, this is best done with an operation. In the future, it may be possible for some people to have it done without major surgery, using a graft placed through a needle into the blood vessel.
The operation to repair an aortic aneurysm is quite serious. In most cases, the operation goes well, and recovery is routine. However, as with all major operations, there are possible complications. The risk of these complications must be balanced against the risk of bleeding from the aneurysm if it is not fixed.
The operation involves replacing the diseased section of the aorta with a dacron cloth tube. This "graft" is a permanent replacement, like a new heart valve. It carries the blood instead of the weakened aorta. In order to place the graft, the surgeon makes an incision in the abdomen, usually up-and-down from the breastbone to the pubic bone. The intestines are moved aside, and the aorta is clamped above and below the aneurysm. The aneurysm is then opened, the blood sucked out and recycled, and the graft sewn into place. In some cases, the aneurysm involves the arteries to the legs; in this case, the graft used looks like an upside-down Y, and the lower ends are sewn to the arteries below the aneurysm. The aneurysm sac is then closed over the graft, and the abdomen is sewn shut.
After the operation, you may need to be on a respirator temporarily to help you breathe. There will be a tube in your mouth connecting you to the respirator, a tube in your nose down to your stomach to drain it so you don't feel nauseated, and a catheter in your bladder to drain urine. There won't be much pain, although all the tubes and iv's can be uncomfortable. Pain medication is usually given through an epidural catheter (a small tube which goes through the back into the spinal canal), and most people are able to rest quite comfortably. If all goes well, you will be able to get out of bed with help the next day. Most people spend one or two days in the intensive care unit. After three days or so, the intestines start working, and the tube in your nose can be removed, and you can start taking liquids. Once you are able to eat and move yourself around, you can go home (about five to seven days). Recovery at home takes about three or four weeks, but most people don't feel back to normal for two or three months.
Risks of operation
This operation is as serious as operations get. The average risk of dying from a complication is less than 5%, but there are other complications which can occur. These include bleeding, pneumonia, heart attack, stroke, kidney failure (which may be temporary or permanent), intestinal damage or obstruction, problems with circulation to the legs which could lead to amputation if severe enough, damage to the spinal cord causing paralysis (possibly permanent), blood clots in the veins which could travel to the lungs, and clotting or infection of the graft (which sometimes happens many years later). All of these complications are unusual, but do occur. The risk of having a major complication from the operation depends on your general health, but is usually less than 10%. Because the operation is so serious, it is not recommended unless the risk from the aneurysm is clearly bigger than the risk of surgery. The surgeon will discuss this with you in detail.
Blood transfusion is often necessary during or after the operation. We use a machine to recycle the blood which is lost, and this can prevent or reduce the need for transfusion. If you require a transfusion, you will have a slight risk of a reaction to the blood or of getting an infection from the blood. All the blood is tested for HIV and hepatitis, and the risk of getting HIV from a blood transfusion is very low - about 1 in 600,000. The risk of getting hepatitis is also low, about 1 in 1,000. We try to avoid blood transfusion, of course, but you will be asked to give permission for it if necessary.
