Abdominal Aortic Aneurysms

An AAA is an increase in aortic diameter by greater than 50% of normal
Usually regarded as aortic diameter of greater than 3 cm diameter
More prevalent in elderly men
Male : female ratio is 4:1
Risk factors - hypertension, peripheral vascular disease, family history
Accounts for 2% male deaths above the age of 55 years
3000 elective and 1,500 emergency operations in Maharashtra each year
Mortality of emergency operation is greater than 50%
Mortality of elective surgery is less than 5%
Selection of patients for operation depends on risk of operation vs. risk of rupture

Natural history

AAA diameter expands exponentially at approximately 10% / year
Risk of rupture increases as aneurysm expands
5 year risk of rupture:
- 5.0 - 5.9 cm = 25%
- 6.0 - 6.9 cm = 35%
- More than 7 cm = 75%
Overall only 15% aneurysms ever rupture
85% of patients with a AAA die from an unrelated cause

AAA are suitable for screening as elective operation of asymptomatic aneurysms can reduce mortality associated with rupture
Who should be screened?
Probably males over 65 years - especially hypertensives
Single US at 65 years reduces death from ruptured AAA by 70% in screened population
Patients with small aneurysms should undergo regular surveillance
Repeated ultrasound every 6 months

75% are asymptomatic
Possible symptoms include
- Epigastric pain
- Back pain
- Malaise and weight loss (with inflammatory aneurysms)
Rupture presents with
- Sudden onset abdominal pain
- Hypovolaemic shock
- Pulsatile epigastric mass
Rare presentations include
- Distal embolic features
- Aorto-caval fistula
- Primary aorto-intestinal fistula

Need to determine
- Extent of aneurysm
- Fitness for operation
Ultrasound, CT Scan
Determines - aneurysm size, relation to renal arteries, involvement of iliac vessels
Most significant post op morbidity and mortality related to cardiac disease
If pre-operative symptoms of cardiac disease need cardiological opinion
May need thallium scan or cardiac catheterisation
Cardiac revascularisation required in up to 10% patients

Introduced into clinical practice with few clinical trials over the past 10 years
Exact role unclear and medium and late-complications only recently recognised
Morbidity of conventional open aneurysm surgery related to
- Exposure of infra-renal aorta
- Cross clamping of aorta
Endovascular repair may be associated with
- Reduced physiological stress
- Reduced morbidity
- Reduced mortality

Endovascular repair achieved by transfemoral or transiliac placement of prosthetic graft
Proximal and distal cuffs / stents anchor graft
Exclude aneurysm from circulation
Three main types of graft
- Aorto-aortic
- Bifurcated aorto-iliac
- Aorto-uniiliac graft with femoro-femoral crossover and contralateral iliac occlusion
Use of technique depends on aneurysm morphology
Aneurysm morphology is best assessed with spiral CT
Only ~40% of aneurysms suitable for this type of repair
Aorto-aortic grafts less frequently used due to high complication rate
Successful stenting associated with reduced aneurysm expansion
Still has 1% per year risk of aneurysm rupture

Dr. Pankaj Patel a vascular surgeon has expertise in peripheral vascular diseases, varicose veins and deep vein thrombosis

Open surgery for Aneurysm repair nowadays is done only on young and fit patients.