The treatment options for asymptomatic AAA are conservative management, surveillance with a view to eventual repair, and immediate repair.
There are currently two modes of repair available for an AAA: open aneurysm repair (OR), and endovascular aneurysm repair (EVAR). An intervention is often recommended if the aneurysm grows more than 1 cm per year or it is bigger than 5.5 cm.
Conservative
Conservative management is indicated in patients where repair carries a high risk of mortality and in patients where repair is unlikely to improve life expectancy. The two mainstays of the conservative treatment are smoking cessation.
Surveillance is indicated in small asymptomatic aneurysms ( less than 5.5 cm ) where the risk of repair exceeds the risk of rupture. As an AAA grows in diameter the risk of rupture increases. Surveillance until the aneurysm has reached a diameter of 5.5 cm has not been shown to have a higher risk as compared to early intervention. The threshold for repair varies slightly from individual to individual, depending on the balance of risks and benefits when considering repair versus ongoing surveillance. The size of an individual's native aorta may influence this, along with the presence of comorbitities that increase operative risk or decrease life expectancy. Studies have suggested possible protective effects of therapy with angiotensin converting enzyme inhibitors, beta-blockers
Surgery
- Open repair
Open repair is indicated in young patients as an elective procedure, or in growing or large, symptomatic or ruptured aneurysms. It was the main surgical intervention used from the 1950s until other procedures developed.
- Endovascular repair
Endovascular repair first became practical in the 1990s and although it is now an established alternative to open repair, its role is yet to be clearly defined. It is generally indicated in older, high-risk patients or patients unfit for open repair. However, endovascular repair is feasible for only a proportion of AAAs, depending on the morphology of the aneurysm. The main advantage over open repair is that there is less peri-operative mortality, less time in intensive care, less time in hospital overall and earlier return to normal activity. Disadvantages of endovascular repair include a requirement for more frequent ongoing hospital reviews, and a higher chance of further procedures being required. According to the latest studies, the EVAR procedure does not offer any benefit for overall survival or health-related quality of life compared to open surgery, although aneurysm-related mortality is lower. In patients unfit for open repair, EVAR plus conservative management was associated with no benefit, more complications, subsequent procedures and higher costs compared to conservative management alone. Endovascular treatment for paraanastomotic aneurysms after aortobiiliac reconstruction is also a possibility.
Further Reading
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"Abdominal aortic aneurysm"
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