management
Once an AAA is diagnosed, management decisions depend mainly on maximum aortic diameter since natural course of AAA is continued expansion and the risk of rupture is exponentially related to diameter (1).
- if aneurysm is less than 5.5 cm - patients should be entered into an ultrasound surveillance programme
- a Cochrane review of two large randomised controlled trials reported that surveillance alone was equivalent to early surgical intervention for aneurysms of 4.0-5.5 cm, but that surveillance was more cost effective.
- data from Chichester trial further suggested that majority of these aneurysms grew slowly enough never to need any intervention
- if aneurysm is greater than 5.5 cm - patients should be referred to vascular specialists for optimisation of medical treatment and consideration of surgical repair (1).
Medical treatment
The optimal medical management of AAAs is unknown. Several important interventions are as follows:
- smoking cessation
- will reduce the risk of AAA
- will reduce aneurysm growth by 15-20% in patients with existing AAA
- will minimise complications if stopped four to eight weeks before surgery
- statins
- the role of statins in the treatment of AAA is unconfirmed, however they are recommended in patients with cardiovascular risk factors
- antihypertensives
- antihypertensives do not appear to be effective in management of AAA
- the role of angiotensin converting enzyme inhibitors is unclear
- a case-control study of 15 326 patients found that use of these drugs was associated with reduced risk of rupture
- however, the UK Small Aneurysm Trial patients taking these drugs had more rapid aneurysm growth—3.33 mm annually versus 2.77 in unmedicated patients and those using other antihypertensive drugs
- β blockers
- no strong evidence exist regarding the use of this drug in reducing the growth of an aneurysm and rupture risk
- β blockers are beneficial in patients with high cardiac risk and if there is time to optimise treatment before surgery
- antiplatelet agents
- European Society for Vascular Surgery guidelines suggest starting low dose aspirin on diagnosis of AAA and continuing indefinitely
Surgical options
Consider aneurysm repair for people with an unruptured abdominal aortic aneurysm (AAA), if it is (4):
- symptomatic
- asymptomatic, larger than 4.0 cm and has grown by more than 1 cm in 1 year (measured inner-to-inner maximum anterior-posterior aortic diameter on ultrasound)
- asymptomatic and 5.5 cm or larger (measured inner-to-inner maximum anterior-posterior aortic diameter on ultrasound)
There are two approaches to repairing aneurysms:
- open repair
- involves making a large incision in the abdomen and inserting a prosthetic graft above and below the aneurysmal tissue (to replace the damaged section of the aorta)
- can also be performed laparoscopically, either by hand-assisted laparoscopic surgery or totally laparoscopic surgery
- 30-day mortality on average is between 4% and 5% (for the past 20 years), hospital stay is on average 9 days
- endovascular repair
- involves a stent–graft being inserted through a small incision in the femoral artery in the groin.
- it is carried to the site of the aneurysm using catheters and guide wires and placed in position under X-ray guidance
- once in position, the stent–graft is anchored to the wall of the aorta using a variety of fixing mechanisms
- is the preferred method for morphologically suitable aneurysms
- has lower operative mortality and morbidity than open repair
- 30-day mortality is approximately 1%, the hospital stay is on average 3 days (1,2,3)
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