What is an abdominal aortic aneurysm?

An abdominal aortic aneurysm (AAA) is where the major artery feeding blood to the lower half of the body is affected. The abdominal aorta is a very large artery and the blood flowing inside is under high pressure, so a weakness in the artery wall may result in an aneurysm. If the aneurysm leaks or bursts, then the health consequences can be extremely serious.

Aneurysms can occur anywhere in the body, but happen mostly on the wall of the aorta. The aorta itself extends from the left side of the heart, runs down through the chest and into the abdomen, where it divides into two branches (iliac arteries).

In England and Wales, between 6,000 and 10,000 people each year experience a rupture of their abdominal aortic aneurysm ⁽¹⁾.

Who is at risk?

Aneurysms can affect anyone regardless of age and sex, but they are commonest in:

• People with hypertension (high blood pressure).
• Men over the age of 60 ⁽¹⁾
• Younger men with a brother or father who has had an aneurysm
• People over the age of 65 ⁽²⁾

What are the main symptoms of an abdominal aortic aneurysm?

• abdominal pain that can spread outward toward the spine
• a pulsing/ throbbing sensation in the abdomen
• back pain

Symptoms of an aneurysm depend on size, how quickly the aneurysm grows and where on the aorta it is. If the aneurysm is small or doesn't enlarge, there are often few or no symptoms, and it may go undetected.

Most aortic aneurysms occur in the abdominal aorta, under the diaphragm (the muscular sheet that separates the chest cavity from the abdominal cavity). You can have this type of aneurysm for a long time and not notice that anything is wrong.

Some abdominal aortic aneurysms are found by GPs during a routine examination of the abdomen. It may be felt as a lump that beats to the same rhythm as the heart. Other patients have their aneurysm discovered when they have a scan for another medical condition, such as kidney or gall stones.

If your GP suspects an abdominal aortic aneurysm, s/he will probably refer you for an ultrasound examination. The ultrasound operator will pass a probe across the abdominal skin right over the suspected aneurysm. The scan will tell the doctor if there is an aneurysm present and how big it is. The procedure is painless, as the detector uses sound waves.

If an abdominal aortic aneurysm increases in size, it may start to press on the spine and organs in the chest, such as the heart and lungs. This causes pain, coughing fits and sometimes problems with swallowing, speaking and breathing.

Am I at risk?

You risk of having an abdominal aortic aneurysm is increased by the following:

• Hardening of the arteries (atherosclerosis), where fatty plaques build up on the inside of the artery wall and damage it
• High blood pressure (hypertension) can increase the risk of the aneurysm bursting
• Genetic factors - aneurysms can run in the family
• Bacterial infections of the heart (bacterial endocarditis)

How is abdominal aortic aneurysm treated?

Not all abdominal aortic aneurysms need an operation because the risk of the artery bursting and the need for an operation depend on the size of the aneurysm.

Rupture risk increases as the aneurysm grows. If it is large, your doctor may decide that an operation to repair it would be better than doing nothing. If the abdominal aortic aneurysm does rupture, your chances of survival are not good.

Only twenty per cent of people who experience a rupture will survive, while 50 per cent will die before they even get to hospital ⁽¹⁾. This is because of massive blood loss into the body cavity.

The operation itself carries a certain amount of risk, so whether you can undergo it or not will be dictated by any other health problems that you might have (co-morbidities). If you have certain lung, kidney or heart diseases, for example, an operation may be more dangerous for you than for someone who is otherwise healthy.

If your aneurysm isn't large, or if it doesn't pose a risk, your consultant will monitor any change in growth with yearly ultrasound scans and advise you if anything has changed or you are in danger.

How will the surgeon repair my abdominal aortic aneurysm?

Most abdominal aortic aneurysms are treated by an operation where the bulging section of artery is replaced with a very strong artificial artery made from a special plastic called Dacron. The artificial artery section is stitched into place and is designed to last for the rest of your life.

Some aneurysms may also be suitable for treatment by a new method called endovascular stenting (EVAR), where the graft is threaded up into the aneurysm through a small incision in each groin. If your aneurysm can be treated with this type of artificial artery, your surgeon will discuss this with you.

Surgical risks for repair of abdominal aortic aneurysm

All surgical procedures carry some form of risk, but for repair of abdominal aortic aneurysm the following can occur ⁽³⁾:

• The risk of death is about one in 20 for open surgery. As mentioned above, risk is lower if you're young and don't suffer from other medical problems (co-morbidities). Death after EVAR surgery is lower (one in 100)
• Infection - antibiotics are given to reduce the risk of infection
• Blood clots can form in the arteries of the toes and feet and deep vein thrombosis can occur in the legs. There is also a risk of blood clots passing to the lung (pulmonary embolism)
• Organ failure
• Blood supply to the spinal cord can be compromised on very rare occasions and can cause paraplegia (paralysis of the legs)
• Leaking of the replacement Dacron artery in open surgery
• After endovascular stenting (EVAR) surgery blood can leak into the old aneurysm, while the stent graft itself can move out of alignment. You will need to have follow-up scans to check that this is not happening

How long does it take to recover from the surgery?

If the repair to your abdominal aortic aneurysm is successful, there is every chance that you can lead a relatively normal life.

Recovery can take between three and six months ⁽³⁾, but this can depend on your age and fitness, whether you smoke or not and if your hypertension is under control. You should always ask your surgeon about risk and how it applies to you individually.

Can I prevent my aneurysm from getting worse?

There is nothing you can do to make your abdominal aortic aneurysm better, but there's nothing you can do to prevent it happening either. Even if you do not need an operation right now, your whole circulatory system will benefit from eating well, taking regular exercise, keeping control of your weight, stopping smoking and lowering cholesterol and blood pressure levels.

Screening programmes

In the UK, offering screening for abdominal aortic aneurysm to men aged 65 years and over was being considered provided that patients are given clear information about the risks of elective (non-emergency) surgery as of March 2007 ⁽⁴⁾.

Infolinks:

• The Vascular Society