Abdominal aortic aneurysms are the most common form of aortic aneurysm, making up three quarters of aortic aneurysm cases. They most commonly occur after the age of 60 years and men are affected about three times more frequently than women are. Each year in New Zealand approximately 400 deaths are attributed to abdominal aortic aneurysms.
The reason why abdominal aortic aneurysms develop is not fully understood. It is known that they have a tendency to run in families, so it is thought that genetic factors may play a role. Other risk factors for developing abdominal aortic aneurysms include:
- Being a male aged over 60 years (around 5% of men overe 60 years of age will develop AAA)
- Atherosclerosis (a build up of fatty deposits in the arteries)
- High blood pressure
- Congenital abnormalities (eg: Marfan’s syndrome)
- Diseases that can weaken the aorta wall (eg: Tuberculosis, Syphilis)
Signs and symptoms
Symptoms of abdominal aortic aneurysms may be vague and non-specific such as backache or abdominal pain. Patients may also note a pulsating bulge in the abdomen – particularly when lying down. An abdominal aortic aneurysm is usually lined by a blood clot. Occasionally, parts of this blood clot can be dislodged and travel downwards to block arteries to the leg (embolism). This may produce symptoms such as pain in the lower legs.
More acute symptoms, which may occur when an abdominal aortic aneurysm is expanding quickly or leaking, can include:
- A deep, pulsating, boring pain in the abdomen
- Pain in the left flank spreading down the left side towards the groin.
If an abdominal aortic aneurysm ruptures, sudden pain, dizziness or weakness may be felt. Loss of consciousness may also occur.
An ultrasound scan is usually the first diagnostic test undertaken to confirm the presence of an abdominal aortic aneurysm. Other tests undertaken to confirm the diagnosis and pinpoint the location and size of the aneurysm may include computerised tomography scan (CT scan) and X-rays. Tests to assess the functioning of the heart, lungs and kidneys may also be undertaken.
Many factors are taken into account when deciding how to treat an abdominal aortic aneurysm:
- The size of the aneurysm – the greater the size, the greater the risk of rupture
- The location of the aneurysm
- The proximity to or involvement with any of the arteries that branch from the aorta
- The person’s general state of health and the presence of other medical conditions.
The two main treatment approaches include watchful waiting and surgical repair:
The two main surgical techniques used to treat an abdominal aortic aneurysm are:
Open Surgical Repair:
During open surgical repair an incision is made in the abdomen and the aneurysm is located and exposed. The aorta is clamped to prevent bleeding and the aneurysm is then opened and repaired, often using a synthetic patch made of Dacron or Teflon. A one to two day stay in an intensive care unit is expected after surgery, followed by a five to 10 day stay in hospital. Complete recovery is usually achieved within two to three months.
Endovascular Stent Graft:
This technique involves inserting a specialised synthetic stent graft into the aneurysm via a tube inserted in an artery in the groin. Under x-ray guidance the graft is fed up into the aorta until it lies within the aneurysm. It is then expanded so that it snugly lines the inside of the aneurysm. This enables blood to flow through the aorta without putting pressure on the aneurysm. This technique only requires a small incision in the groin and has the advantage of a shorter hospital stay and a much quicker recovery time.
Nair, N., Sarfati, D., Shaw, C. (2012) Population screening for abdominal aortic aneurysm: evaluating the evidence against screening criteria. In the New Zealand Medical Journal. 24-February-2012, Vol 125 No 1350