An aneurysm is a bulge in an artery due to the weakening of its wall. The bulge or "ballooning" of the artery may grow larger and eventually tear or rupture if it is not diagnosed and treated. One of the most common places for aneurysms to form is in the aorta, which is the main artery that goes from your heart down to the chest, kidneys, intestines and other organs in the abdomen and pelvis. In the abdomen the aorta divides into the arteries that supply the legs. Aneurysms of the abdominal aorta (AAA) occur between the diaphragm (the muscle that divides the chest cavity from the abdomen) and the place where the aorta divides (near the umbilicus, "belly button"). Sometimes aneurysms can extend above and below this area. If the AAA continues to expand, it will eventually rupture and cause death.
About 15,000 people die of a ruptured AAA in the United States every year. A ruptured AAA is a truly life-threatening emergency and must be repaired immediately to prevent death and disability.
Causes of Aneurysms of the Abdominal Aorta
Proteins in the wall of the aorta, called elastin and collagen, provide strength and flexibility to this large artery. Aneurysms are caused by the breakdown of these proteins that then lead to a weakness of the wall. This can cause the walls to expand like a balloon. These proteins, collagen and elastin, may gradually deteriorate with age. Inflammation that often accompanies atherosclerosis (hardening of the arteries) helps to speed up this degenerative process. Some of the body's naturally occurring enzymes may also cause the breakdown of collagen and elastin in the wall of the aorta. An excess of these enzymes or conditions that activate the enzymes may cause the formation of an aneurysm, or lead to its sudden growth in size. In rare cases an aneurysm may be caused by infection or injury.
Symptoms of AAA
Usually there are no symptoms associated with AAA. Sometimes a patient will notice a particularly strong pulse in the abdomen, but this is also noticeable in a thin person with a normal aorta. When symptoms do occur, they are generally lower abdominal or back pain. Most AAA's are found during tests (particularly x-rays) that are performed for other reasons.
The older you are, the higher your risk of aneurysms of the abdominal aorta . Men are also more likely to have an AAA than women. Smoking greatly increases your risk eight-fold.
Risk Factors for Aneurysms of the abdominal aorta
- Age over 60 years
- Family history of abdominal aorta aneurysms
- Tobacco use
- History of heart disease
- History of peripheral arterial disease (PAD)
- High blood pressure (hypertension)
If you have a family history of AAA, you should discuss this with your health-care provider, especially if you have any of the other risks for AAA.
Diagnosis of AAA
Early diagnosis of AAA is essential to prevent rupture, death or disability. Knowing your risk factors and discussing them with your health-care provider are very important. Tests to diagnose AAA are simple and require an ultrasound or CT scan to identify the aneurysm and also measure its size. AAA can also be identified by physical examination, but this is difficult if the person is overweight.
Treatment of AAA
Treatment before rupture is very important. AAA's that are 5-6 centimeters (lemon-sized) need to be repaired. Those that are smaller and cause no symptoms can be watched carefully, so that if they grow, they can be repaired. The method of repair depends upon the size and place of the AAA as well as on the general health of the person needing the repair. Only your doctor can decide which method is appropriate for you.
For over 50 years, the standard treatment of AAA has been to replace the area with a synthetic graft in the operating room under anesthesia. These are very durable and permanently cure the AAA. Most patients stay in the hospital for up to 10 days and enjoy full recovery in several months.
More recently, less invasive methods of AAA repair have emerged. Now, endovascular grafting technology repairs AAA by inserting a graft through small incisions in the groin. The endovascular method delivers the graft through a catheter or tube inserted in the groin arteries. X-ray guidance is then used to position the graft accurately in the AAA. The graft is then expanded inside the aorta and held in place with metallic hooks rather than sutures. The hospital stay is usually only one or two days, and most patients can return to work or normal daily activities in about a week. Endovascular grafts are followed regularly with scans to check on the status of the repair.
Not everyone is a candidate for endovascular repair. Graphs may not be a good fit for some AAA's and open surgery may be the only option.
With early detection and treatment, an AAA is a very treatable problem. Be sure to discuss risk factors with your health-care provider and ask questions.