Abdominal Aortic Aneurysm

Question 1

Define Abdominal Aortic Aneurysm

Answer 1

Abdominal aortic aneurysm is a permanent pathological dilation of ALL 3 LAYERS of the aorta with a diameter >1.5x the expected anteroposterior (AP) diameter of that segment, given the patient’s sex and body size

• AAAs are classified by location as either suprarenal or infrarenal aneurysms.
• More than 90% of aneurysms are infrarenal

Question 2

Explain the aetiology / risk factors of an abdominal aortic aneurysm

Answer 2

• Smoking (most important risk factor)
• Advanced age
• Positive family history
• Hypertension
• Hyperlipidaemia
• COPD
• Connective tissue disorders (Marfan’s, Ehler-Danlos)
• Atherosclerosis

Question 3

Summarise the epidemiology of AAA

Answer 3

• Males (5x more likely)
• Rupture likelihood is more common in Females
• 60-70 years

Question 4

Recognise the presenting symptoms of an abdominal aortic aneurysm

Answer 4

• Usually ASYMPTOMATIC and an incidental finding
• May have lower back, abdominal or groin pain especially if RUPTURED (abdominal aorta has many tiny perforators going to supply the back muscles so AAA rupture causes ischaemic pain)

Question 5

Signs on Physical Examination

Answer 5

Triad of Ruptured AAA:

• Laterally expansile and palpable pulsatile mass in the abdomen
• Hypotension
• Lower back/Abdominal pain
• Cullen’s sign/Grey-Turner’s sign

Question 6

Investigations

Answer 6

1ST LINE: Abdominal Ultrasound

• abdominal aortic dilation of >1.5 x the expected anterior-posterior diameter of that segment
• This is also used for surveillance –> All men between 65 and 75 years of age with a history of smo​king should be screened once with an ultrasound to exclude an AAA
  
  • An AAA between 3-4.4cm are scanned annually
  • An AAA between 4.4.-5.4cm are scanned every 3 months
  • An AAA >5.5cm OR >4 cm and rapidly enlarging (>1cm/year) requires 2 week vascular referral for repair
  • symptomatic AAA (e.g. back pain) REGARDLESS OF SIZE require URGENT ENDOVASCULAR REPAIR

CT Angiography is better as visualising aneurysms close to the origins of, or proximal to, the renal arteries.

MRI Angiography can be used if allergic to iodinated contrast

Question 7

Management

Answer 7

Conservative

• stop smoking (offer smoking cessation)

Medical

• Optimise/Initiate anti-hypertensive treatment

Surgical (aortic repair)

• Open laparotomy aortic repair if ruptured AAA and haemodynamically unstable
• Endovascular repair (EVAR) if:
  
  • AAA diameter >5.5cm
  • AAA any size growing >1cm/year
  • AAA any size if symptomatic (pain)