Abdominal aortic aneurysm
First let us define some terms:
AAA are present in about one in twenty men (5%) and one in fifty to a hundred (1-2%) women aged over 60 years. The main risk factors are smoking and high blood pressure and, possibly, high cholesterol levels.
If an AAA is large then it may be felt either by the patient or their doctor on examination. However, as the swelling in the tummy is usually non-tender and grows very slowly, many patients are unaware that they have an AAA. If a patient has a waist circumference of greater than 42 inches then even if the AAA is large there is a greater than 50% chance that even an experienced doctor will not be able to feel it on abdominal examination.
For these reasons all patients suspected of having an AAA should undergo an ultrasound scan of their abdomen to confirm (or refute) the diagnosis and to obtain an accurate measurement of the size of any aneurysm detected.
Most patients with AAA do not know they have one and most do not cause any symptoms until, suddenly one day, they burst (called a ruptured AAA) usually without any warning. Only about 10% of patients who suffer a ruptured AAA survive.
The treatment of AAA depends largely on their size as the bigger an AAA the more likely it is to burst (rupture) and cause premature death:
*The estimated 5 year risk is more than 5 times the estimated annual risk because over that 5 years the AAA, if left untreated, will continue to grow in size
All patients found to have an AAA should be started on Best Medical Therapy (BMT) comprising:
BMT will reduce the risks of the AAA growing and so the risks of rupture.
Once formed, most AAA continue to grow in size; especially if patients continue to smoke and do not control their blood pressure. The rate of growth is unpredictable so all patients with an AAA should be enrolled in an AAA surveillance programme where patients are seen and examined, and undergo an ultrasound scan of their abdomen, every 3-6 months.
Large trials have indicated that, in general, the risks of repairing small AAA outweigh the benefits. So, unless an AAA is causing pain or other symptoms (which is unusual) most vascular surgeons will not recommend repairing an AAA unless it exceeds 5.5cm in maximum diameter.
There are two ways of repairing an AAA:
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