Abdominal aortic aneurysm

What is an abdominal aortic aneurysm (AAA)?

Aorta is the largest artery of the body and its normal diameter is up to 28mm in the chest and around 20mm in the abdomen. When a weak area of the abdominal aorta bulges or expands to reach over 1.5-2 times its normal diameter, it is called an abdominal aortic aneurysm (AAA).

The pressure of the blood with every heart beat can cause a weakened area of the aorta to gradually bulge (much like a balloon).

If the aneurysm is not treated, the aortic wall continues to weaken and the aneurysm to enlarge. Eventually, the aneurysm becomes large enough and its wall too weak and bursts (ruptures). A ruptured aneurysm can cause very severe internal bleeding leading to shock and death in most cases.

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What are the symptoms?

Most people with an aneurysm do not have symptoms, and it is usually diagnosed by investigations done for irrelevant reasons.

If you have symptoms, these may be:

• Feeling of pulsations in your abdomen, similar to a heartbeat
• Severe, sudden pain in the abdomen or the lower back. On this occasion, it is likely that the aneurysm is about to rupture
• In rare cases, your feet and toes may develop areas with bluish discolouration and pain, because of embolization (shedding of debris downstream) from the the aneurysm (“blue toe syndrome”)

If the aneurysm ruptures, you may feel intense weakness, dizziness or pain and lose consciousness. This is a life threatening situation and you should immediately seek medical care.

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Who is at risk of developing an abdominal aortic aneurysm?

Abdominal aortic aneurysms are commoner in men. You are at increased risk of developing an AAA if you are:

• A man over 60 years of age. The risk increases with the age. Among men of 65-80, the percentage of those with an AAA is 2-5%. Among women of the same age, the percenage is up to 1%
• A smoker
• A man whose father or brother has/had got an aneurysm
• A man with either coronary or peripheral arterial disease

Although hypertension, or high blood pressure, (especially if not well controlled) would intuitively seem to enhance the development and expansion of AAA, it has not been documented to be a factor in population-based studies (Risk factors associated with abdominal aortic aneurysm: a population-based study with historical and current data. Journal of Vascular Surgery, 2005).

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How is an abdominal aortic aneurysm diagnosed?

The simplest way to diagnose an AAA is by ultrasound scanning of the abdomen. If your physician suspects you might have an aneurysm, he/she may organize one of the following imaging investigations: duplex ultrasonography of the abdominal aorta & the iliac arteries, computed tomography (CT) or magnetic resonance imaging (MRI) of the abdomen.

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Do I need treatment?

Not all abdominal aortic aneurysms require repair. The risk for rupture, and consequenlty the indication for repair, increases together with the size of the AAA.

Whether you need operative repair for your AAA or not shall be decided by your vascular surgeon who is the only physician capable of performing all types of AAA repair.

If the AAA is large enough (over 50mm), it is generally safer for you to have it repaired. Because the operation carries certain risks, the exact size for which the operation will be elected depends upon any other medical conditions you may have. For example, heart, lung or kidney problems increase the surgical risk. After successful open surgical repair the risk for rupture is zero. Ideally, repair will be recommended when the rupture risk is higher than the surgical risk. Your vascular surgeon will discuss with you in detail the possible risks and complications of the operation.

If your AAA is smaller (30-50mm), your vascular surgeon will generally recommend watchful waiting with follow-up ultrasound scans (usually every 6-12 months).

Abdominal aortic aneurysms in general grow slowly. However, the larger they are, the faster they grow.

If rupture of an abdominal aortic aneurysm occurs, the chance of survival is less than 20%.

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What is the treatment?

The approach may be one of the following:

• Watchful waiting – As mentioned above, aneurysms less than 50mm in diameter, should be followed up every 6-12 months for signs of change with an imaging investigation such as duplex ultrasonography or computed tomography (CT). If you are a smoker you need to quit and if you have a high blood pressure you need to take your relevant medications regularly. Your physician is likely to recommend that you take an antiplatelet drug (Aspirin or similar) and a statin. It is crucial to comply with the medical instructions.
• (Open) surgical repair – If an aneurysm has a maximal diameter of over 50-55mm, if its expansion rate is faster than average regardless of its size, or if symptoms (pain in the abdomen or lower back) in the persence of an aorto-iliac aneurysm of any size occur, repair will probably be required.
• Endovascular repair (EVAR) – Some aneurysms are suitable for repair with this modern method which involves insertion of a stented graft inside the aneurysm via a small insicion in each groin. If your AAA is suitable for this type of repair, your vascular surgeon will discuss it with you.

Most people with an AAA will eventually need repair of their aneurysm with a graft.

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What does the open operation involve?

For open repair, through an incision in your abdomen, the weakened part of your aorta is replaced with a graft, or a plastic tube, which allows your blood to flow through it.

The graft is made of very strong durable plastic material either Dacron (polyester) or polytetrafluorethylene (PTFE) in the size of normal aorta. The graft lasts for a lifetime and is very unlikely to require replacement. The operation is successful in 90-98% of cases.

Following the operation you will stay in the hopital for 5-8 days. It will take you 2-3 months for a complete recovery, but this period depends on your biological age.

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What does the endovascular operation involve?

Instead of the open repair, your vascular surgeon may consider this newer procedure, the endovascular repair. Endovascular or endoluminal means that the procedure is done through the wall of your arteries inside their lumen using very fine and long tubes, called catheters. This type of operation is less invasive and may be performed under regional anasthesia.

Initially, a small incision is made in each groin area. During the procedure, the vascular team will use x-ray pictures viewed on a screen to guide a tube (made of plastic and metal material), called stented graft or endograft, to the site of the aneurysm. Like the graft in open repair the endograft reinforces the aorta.

Your recovery time after EVAR is shorter than with the open repair and hospital stay may be reduced to 2-3 days. However, this procedure requires follow-up for a long time (probably for your lifetime) with imaging inestigations, currently CT scans, to confirm that it continues to function properly.

Your aneurysm may not be suitable for this procedure, because of its shape, its extent, its relation to the renal arteries etc. While endovascular repair may be a good option for some patients, in other cases open repair may be the best way to cure the problem.

Your vascular surgeon is the only physician qualified to offer all types of treatment for an AAA, and will help you decide the best method of repair in your particular situation.

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What can I do to help myself?

It is prudent to improve your general health state even if you don’t need an operation at present:

• Quit smoking completely
• Exercise aerobically (brisk walking, cycling etc) for 25 to 30 minutes daily
• Maintain your ideal body weight
• Eat foods low in animal fat, cholesterol, and calories
• Avoid lifting weights over 10kg
• Take your medication to control blood pressure, blood cholesterol and diabetes

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