There is a natural tendency for an AAA to dilate until rupture occurs, unless the patient dies from other causes. The decision to repair an AAA is based on the patients operative risk balanced against risk of aneurysm rupture. Therefore the main factors in this equation are the size of the aneurysm and the general health of the patient (principally the presence of cardiac, respiratory, renal and peripheral arterial disease).
Current opinion suggests that symptomatic, rapidly expanding or ruptured aneurysms should be repaired as long as the patient’s co-morbidity and quality of life do not preclude operation. The UK small aneurysm trial concluded that asymptomatic AAAs of diameter < 5.5cm can be managed by continued ultrasound surveillance. Therefore the current recommendation in asymptomatic AAAs is to consider surgery in patients with an aneurysm diameter > 5.5 cm or with an expansion of > 1cm/year. Small aneurysms require regular ultrasound surveillance, annually for those with AP diameter 3.5- 3.9 and 6 monthly for those between 4-5.5cm.
Medical management of small AAAs involves treating the risk factors such as smoking, hypertension, and hypercholesterolaemia. Experimental evidence suggests that drugs such as Doxycycline (a matrix metalloproteinase inhibitor) and statins may have the potential to reduce aneurysm expansion but results of clinical trials are awaited.
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