What is an abdominal aortic aneurysm?

An abdominal aortic aneurysm (AAA) is a dilatation or ballooning of the major artery in the abdomen that takes blood from the heart to the intestines, kidneys, liver and to the legs. Aneurysms, or enlarged arteries, can affect arteries throughout the body, but tend to occur in the lowest part of the aorta, just above the belly button. They occur mainly in elderly males and those with a family history of AAAs.

The normal aorta is about 2cm in diameter. Due to weakness in the artery wall caused by smoking, hypertension or genetic predisposition, the aorta can dilate (get larger) over many years. If it dilates out to about 5cm, then there is a significant risk that the aorta will rupture, causing massive internal bleeding which usually leads to death within minutes to hours. Thus, once the aneurysm reaches a diameter of 5cm, treatment is the preferred option to prevent it from rupturing.

AAA treatments

Abdominal aortic aneurysm surgery has been practised for over 60 years. It is a major operation with a high chance of complications and a long recovery period. Open surgery involves a long incision in the abdomen and repairing the AAA by suturing a bypass graft into it. However, although open surgery is occasionally still required to repair an aneurysm, almost 80% of all AAAs are now repaired via minimally invasive stenting procedures.

The stenting of an AAA involves a small incision in each groin (to get access to the femoral arteries) and with the aid of sophisticated X-ray equipment, a stent is placed in the correct position to repair the AAA. It requires only a 1-2 day stay in hospital with a very quick recovery time.

Dr Shakibaie has treated many aneurysms with both minimally invasive methods and surgery when required. During the initial consultation, he will discuss the management of your aneurysm and answer any questions you may have about abdominal aortic aneurysms.

An abdominal aortic aneurysm (AAA) is a ballooning outwards of the wall of the aorta. The aorta is the major artery that supplies blood to most of the body. If an aneurysm develops, it means that the wall of the aorta has weakened and could be at risk of rupturing. A rupture of an abdominal aortic aneurysm causes massive internal bleeding and is almost always fatal.

Causes of abdominal aortic aneurysm

Abdominal aortic aneurysm is not often seen in people under the age of 50, but its prevalence increases significantly as age increases. About 4-7% of men and 1-2% of women aged 65 years or older are affected by AAA.

Factors which put someone at higher risk of having an abdominal aortic aneurysm include:

  • Smoking
  • Family history
  • Increased age
  • Male

Men are more likely to have an abdominal aortic aneurysm than women, but women are more likely to have an AAA rupture.

Abdominal aortic aneurysm symptoms

An abdominal aortic aneurysm often has no obvious symptoms and is only discovered through screening or by tests done for other reasons. Sometimes people with an abdominal aortic aneurysm may have pain in their abdomen, groin or back.  

Examinations and investigations

Patients who have a number of risk factors and are suspected to have an AAA will be sent for imaging tests.

Abdominal ultrasound is widely used to check for the presence (or absence) of an aneurysm and to measure its size.  In order for AAA to be diagnosed, the aorta must have dilated to at least 1.5 times its normal diameter. Ultrasounds are inexpensive, non-invasive and reliable for diagnosing AAA.

Alternatively, doctors may perform an abdominal computed tomography angiography, which is usually done if surgery is being considered.

Abdominal aortic aneurysm stenting or surgery is usually the recommended treatment in order to repair an abdominal aortic aneurysm. However, surgery may not be necessary depending on the size of the aneurysm.  Intervention may not be recommended for small aneurysms because the likelihood of the aneurysm bursting is low. Similarly, for some people who have other health conditions or problems, the risks of intervention may outweigh the benefits. People who have a small AAA and no symptoms are usually monitored with abdominal ultrasounds at regular intervals and are not advised to have surgery straight away.

Ruptured AAA

The risk of an AAA rupturing increases significantly as the size of the AAA grows. For example, an AAA smaller than 4 cm in diameter has a less than 0.5% risk of rupturing in a given year, whereas an AAA with a diameter greater than 8 cm has a 30-50% annual risk of rupturing.

Generally, people who have an AAA with the following characteristics are usually recommended for surgery to repair the AAA:

  • AAA with symptoms
  • AAA greater than 5.0 cm in diameter (male)
  • AAA that is rapidly growing by more than 1 cm a year

There are two types of surgeries that are performed to repair AAAs: open repair and endovascular aneurysm repair.

Open AAA repair

In an open repair of an AAA, the surgeon will make an incision in the abdomen and remove the section of the aorta that has swelled, replacing it with a tube that is then sutured into place.

The surgery will usually last between two and four hours and is performed under a general anaesthetic and has a long recovery period.

Endovascular aneurysm repair (EVAR)

Endovascular aneurysm repair is a less invasive procedure that is used to repair abdominal aortic aneurysms. It involves the surgeon making a small incision in the groin. Using small tools, they can access the AAA through the femoral arteries (the large arteries in the legs). The surgeon then places a stent-graft of an artificial artery-like substance into the aneurysm under x-ray guidance. This allows the blood to flow through the stent-graft rather than the aneurysm, relieving pressure on the weakened wall and preventing it from rupturing. It can be performed under a general or regional anaesthetic.

EVAR is a newer procedure and given that it is less invasive, it has a faster recovery than open repair. You can usually return home within 2-3 days. 

People with an AAA must meet certain criteria in order to be eligible for EVAR. The part of the aorta near the aneurysm should be clear of blockage, be long enough and not too wide in order for EVAR to be successful. If EVAR is performed under unfavourable conditions, then there can be an increased risk of the procedure not working or complications  after the operation.