AAA Flashcards
What is an aneurysm?
An aneurysm is an abnormal dilation of an artery such that it is greater than 50% of its transverse diameter.
ARTERIAL ECTASIA: dilation of up to 50%
ARTERIOMEGALY: generalised dilation of the arteries
What is a false aneurysm?
True aneurysms are abnormal dilatations that involve all layers of the arterial wall. False aneurysm (pseudoaneurysms) involve a collection of blood in the outer layer only which communicates with the lumen (e.g. after trauma).
What are the two main types of aneurysms?
Aneurysms may be fusiform or sac-like (e.g. berry aneurysms).
What causes an aneurysm?
Atherosclerotic’ disease – degenerative and increasing risk with age
Infection e.g. mycotic aneurysm in endocarditis tertiary syphilis
Inflammatory (10%) e.g. Takayasu’s aortitis
Connective tissue disorder – Marfans syndrome or Ehlers-Danlos syndromes
Where are the common site of an aneurysm?
Aorta, iliac, femoral and popliteal. Other = Visceral (splenic most commonly) and Intracerebral
Describe an aortic aneurysm
An aortic aneurysm is a swelling (dilation or aneurysm) of the aorta to greater than 1.5 times its normal size. It usually represents an underlying weakness in the wall of the aorta and is associated with extensive artherosclerosis in the adjoining regions of the aorta. An abdominal aortic aneurysm (AAA) is the most common type of aortic aneurysm. An AAA may remain asymptomatic for long periods, but there is an increasing risk of rupture if > 5.5 cm.
How is an aneurysm measured and why does size matter?
Aneurysm size is important as it often provides a threshold for surgery
The size of the aneurysms is measured by the maximum transverse diameter. o Normal aorta < 2.5cm o Ectasia < 3.5cm o Small AAA < 4.5cm o Large AAA >5.5cm
Rupture is exponentially associated with MTD
o ~ 1% Annual risk at 4cm
o ~ 7% Annual risk at 6cm
o ~ 50% Annual risk at 8cm
What are the symptoms of an AAA?
– Asymptomatic
– Back pain
– Tenderness
– Limb ischaemia (occasionally)
What are the potential complications of an AAA?
Rupture, thrombosis, embolism, fistulae, pressure on other structure
What are the risk factors of an AAA?
– Male gender (4:1) – Age (60+) – Hypertension – Smoking – Family history of AAA
If risk factors are present the patient has an increased risk of developing an AAA (1 in 6) compare to the risk when risk factors are not present (1 in 25)
AAA are usually incidental findings during investigation for something else (75%) or are detected at national screening programmes for males aged 60+.
When is intervention for a AAA required and what does intervention entail?
If the patient is symptomatic then we intervene regardless of size
If the aneurysm is under 5.5cm - surveillance scan
If the aneurysm is over 5.5cm - intervene on risk balance
Open surgery: replace affected segment with plastic graft, tube or bifurcate
– GA
– Major cardiovascular stress from XC
– Mortality 5% and upwards, usually cardiac
Endovascular surgery: reline aorta – Spinal – reduced CV stress – Mortality ~2% – Only ~70% of aneurysms suitable (approx.) as they need to have a proximal infrarenal aortic neck, and the aneurysms must be clear of the iliac arteries – Lifelong follow-up with CT or Duplex – 6-8% per annum failure rate o Endoleak: sac repressurization o Endovascular reinterventions usually possible
What are the signs and symptoms of a ruptured AAA?
• Symptoms and signs: intermittent or continuous abdominal pain (radiates to the back, iliac fossa or groins), collapse, an expansile abdominal mass or shock
Which factors increase the likelihood of a rupture?
A rupture is more likely if the patients has a high blood pressure, is a smoker, is a female and if they have a strong family history.
