Aortic Aneurysms
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WHAT IS AN ABDOMINAL AORTIC ANEURYSM (AAA)
When an artery wall weakens it can bulge out and expand. This is called an aneurysm.
The exact cause is not fully understood but can be contributed from a genetic component.
The most common site is in the abdominal aorta which is a large artery that carries blood from the heart through the abdomen to the legs. In rare instances aneurysms can occur following trauma to the artery or infections of the blood stream. Abdominal aortic aneurysms (AAA or “triple A”) are the most common occurring aneurysm, however they can affect any artery in the body.
WHAT IS THE SIGNIFICANCE OF AAA?
The serious danger of an aneurysm is that it can rupture, resulting in profuse bleeding and death. The risk of aneurysm rupture rises exponentially with the size of the aneurysm and surgical intervention is recommended once the aneurysm is 5.5cm or greater in diameter. This may vary for each individual patient depending on their general health and fitness for surgery.
Once the AAA has ruptured, the chance of dying is greater than 70%. These deaths are avoidable with early diagnosis, surveillance and treatment.
HOW ARE AAA DIAGNOSED?
Abdominal aortic aneurysms gradually enlarge over many years. Patients often do not develop symptoms before reaching a critical size or rupture. However, they can be identified by regular physical examination and ultrasound.
If something suspicious is found the examining doctor will recommend an ultrasound to determine the precise location and size. Advanced tests like a CT or MRI may also be recommended.
Once an aneurysm has been diagnosed, an angiogram may be required to plan treatment.
HOW IS AN ABDOMINAL AORTIC ANEURYSM TREATED?
There is no medical treatment for aneurysms. People with small aneurysms are encouraged to not smoke and control their blood pressure.
There are two methods to repair aneurysms. Both involve surgery.
Open Surgical Repair
The traditional treatment for AAA is a surgical procedure performed under general anaesthetic. The surgeon opens the aneurysm and sews a vascular graft in place to replace the diseased artery. In skilled hands, this procedure can be performed with low morbidity/mortality. This is major surgery but it is important to note, however, that once the AAA is repaired by open surgery it is uncommon that there will be any lasting problems or need for further intervention.
Endovascular 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 endograft is delivered through the catheter and placed inside the aneurysm. This endograft 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. Patients go home the next day and frequently are able to resume normal activity by one week.
Complications such as gangrene of the leg, claudication, kidney failure, bowel ischaemia, need for colostomy, pneumonia, paralysis and heart attack can still occur 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 twenty percent of patients may require a further procedure in the future to fix problems that may develop over time with the graft or the aneurysm sac. Therefore long-term surveillance of the patient must be performed usually by means of a CT scan or ultrasound. A few patients have ruptured the AAA despite an apparently successful procedure.