What is an abdominal aortic aneurysm (AAA)?
An aneurysm is a blood vessel whose wall has become weak and allows the blood vessel to expand and bulge out. Most aneurysms have no definite cause, although most are associated with atherosclerosis. The most common site is in the abdominal aorta, the large artery that carries blood from the heart through the abdomen to the legs. This is called an abdominal aortic aneurysm (AAA). Aneurysms sometimes occur in the branches of the aorta that go to the legs (iliac arteries) and in the legs themselves in the popliteal artery, the main artery that runs behind the knee.
What is the significance of an AAA?
The most significant risk of an aneurysm is rupture, which results in severe bleeding and death if not corrected with surgery. Sometimes an aneurysm will fill with blood clot that can break loose causing a blockage in the downstream arteries. AAA causes more than 10,000 deaths per year in the USA and many of these are preventable through early diagnosis and treatment. Approximately 50,000 patients undergo surgery for AAA in the USA alone every year.
Who is at risk of AAA?
After the age of 65 a man has a risk of approximately 7%, whereas it less <1% for a woman. By the age of 80 the risk is up to 10% for a male vs. 2% for a woman. A person's risk is also increased with a family history of AAA.
Patients who are at increased risk of AAA:
- Smokers
- Patients with circulation problems in the legs
- Emphysema
- Coronary artery disease
- Carotid artery disease, prior stroke, or ministroke
- High blood pressure
How are AAA diagnosed?
Aneurysms in the abdominal area enlarge slowly over a period of years. In theory, this means they can be discovered before they cause problems. Unfortunately, aneurysms frequently produce no symptoms before they leak or rupture that would prompt a person to seek medical attention. But they can be picked up at a regular physical examination. For example, an abdominal aneurysm often feels like a tender, throbbing lump under the skin and the patient or an examining doctor may discover the pulsating mass. Even if the lump cannot be felt, the doctor can often hear suspicious sounds of turbulent blood flow through a stethoscope on the abdomen.
When an examining doctor discovers signs suspicious of an abdominal aneurysm, an abdominal X-ray or ultrasound examination may reveal its size and location. More advanced tests, like a CT scan and M.R.I., are usually included in the diagnostic workup. Some vascular specialists, ourselves included, recommend that ultrasound, a simple, quick, non-invasive test, be used to screen people at high risk of abdominal aneurysm. Once an aneurysm has been diagnosed an arteriogram (angiogram) may be required to plan treatment.
What are the different treatments for AAA?
There is no drug that has been shown to treat aneurysms effectively. Patients are encouraged to stop smoking and to control their other medical conditions such as hypertension.
There are two methods to repair aneurysms, and both involve surgery.
Open Surgery: The traditional treatment for AAA is a surgical procedure performed under general anesthesia. An incision is made in the abdomen and the surgeon replaces the diseased artery with an artificial graft. In skilled hands, this procedure can be performed with a mortality of 2-5%. Patients stay approximately 5-7 days in the hospital. Patients usually recover fully by 6 weeks . Although very rare, complications such as gangrene of the legs, kidney failure, need for a colostomy, pneumonia, and even paralysis can occur. Because this is major surgery, heart attacks may also unusually complicate these operations. For this reason it is sometimes recommended that patients have a cardiology checkup, which may include a stress test, prior to surgery. In some men sexual dysfunction can occur. Rarely this may be impotence, but in some men a condition known as retrograde ejaculation can result. This implies that vaginal penetration and orgasm still can be achieved, but the semen ejaculates into the bladder rather than externally. This can result in infertility. It is important to note, however, that once the AAA is repaired by open surgery it is rare that there will be any lasting problems or need for further intervention.
Endovascular repair (stent-graft repair): In this new, less invasive technique, a catheter, or small tube, is inserted into the arteries through a small incision in the groin. Under x-ray guidance, a vascular stent graft is delivered through the catheter and placed inside the aneurysm. This graft fits snugly into the normal artery above and below the aneurysm and so forms a new pathway for the blood to flow thus excluding the aneurysm sac, which then usually goes on to shrink. Patients usually go home the next day and frequently are able to resume normal activity by one week, although hospital stay and recovery time varies from patient to patient. Complications such as gangrene of the leg, claudication, kidney failure, need for colostomy, pneumonia, paralysis and heart attack can also with this procedure, however sexual dysfunction should not occur. Unfortunately, not all patients are candidates for this type of procedure. The vascular surgeon must evaluate each patient on a case-by-case basis and approximately ten percent of patients may require a further procedure at some stage in the future to fix problems that may develop overtime with the graft or the aneurysm. Normally, these procedures can be performed as an outpatient. Because this is a relatively new procedure, long-term surveillance of the patient must be performed usually by means of a CAT scan or ultrasound test. A few patients have ruptured the AAA despite an apparently successful procedure.
Who should undergo treatment for AAA?
The risk of rupture for aneurysms under 5.0 centimeters in diameter is small, and there is little benefit for treatment for aneurysms under this size unless patients have symptoms related to the aneurysm. Once the aneurysm reaches 5.0 cm in diameter, the risk of rupture increases significantly, and repair is usually recommended. Under such circumstances most surgeons would advise repair of the aneurysm unless the patient has severe medical conditions that would make surgery too risky.
Testing for Abdominal Aneurysm can be done in our office and Vascular Lab Appointment Request