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

	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

Screening

	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

	Rupture
	Symptomatic aneurysm
	Rapid expansion
	Asymptomatic > 6 cm - exact lower limit controversial

Pre-operative investigation

Need to determine   Extent of aneurysm Fitness for operation Ultrasound, conventional CT and more recently spiral CT 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

Endovascular aneurysm repair

	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

Technique

	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

Complications

	Graft migration
	Endovascular leak
	Graft kinking
	Graft occlusion

Popliteal artery aneurysms

	Defined as a popliteal artery diameter greater than 2 cm
	Account for 80% of all peripheral aneurysms
	50% are bilateral
	50% are associated with an abdominal aortic aneurysm
	50% are asymptomatic
	Symptomatic aneurysms present with features of:
Compression of adjacent structures (veins or nerves) Rupture   Limb ischaemia due to emboli or acute thrombosis
	Treatment is by proximal and distal ligation
	Revascularisation of the leg with a femoropopliteal bypass
	With a symptomatic popliteal aneurysm 20% patients will undergo an amputation