Abdominal aortic aneurysm

Question 1

Define Abdominal aortic aneurysm

Answer 1

Permanent pathological dilation of the aorta with a diameter >1.5x the expected AP diameter of that segment, given the patient’s sex and body size

Commonly 3cm or more

Question 2

Aetiology of abdominal aortic aneurysm

Answer 2

Atherosclerotic disease
Either fusiform (equally round) or saccular (outpouching)
Loeys-Dietz syndrome

Classification:
- Congenital: bicuspid aortic valves and Marfan’s
- Infectious: aortic wall infection by Staph and salmonella
- Inflammation

Loeys-Dietz syndrome is typically associated with findings of hypertelorism, a bifid uvula, and increased arterial tortuosity. It is highly associated with aortic aneurysms and dissections, and regular screening echocardiograms must be initiated for these patients

Question 3

Risk factors for abdominal aortic aneurysm

Answer 3

Smoking
Family history
Increased age
Male sex
Congenital/connective tissue disorders
Hyperlipidaemia, COPD, atherosclerosis, HTN, height, central obesity, non-diabetic

Question 4

Symptoms of abdominal aortic aneurysm

Answer 4

Usually symptomatic

Epigastric pain that radiates to the back (May also be back or groin), intermittent/continuous

Question 5

Signs of abdominal aortic aneurysm

Answer 5

Palpable pulsatile expansile abdominal mass (thin patients, AAA>5cm)
Hypotension
Retroperitoneal bleed - Grey Turner’s or Cullen’s

Question 6

Investigations for abdominal aortic aneurysm

Answer 6

ESR/CRP: elevated
FBC: leucocytosis and anaemia
cultures +ve if infectious cause

Abdominal USS: >1.5x the expected
CT/MRI: dilation >1.5x expected AP diameter

Question 7

What is the standard follow up for unruptured abdominal aortic aneurysm

Answer 7

USS to assess diameter
<3 - normal
<4.4 - yearly scan
4.5-5.5 - every 3 months
>5.5, - 2 week referral for surgery

Question 8

What is the screening for abdominal aortic aneurysm

Answer 8

Single screen for all men at 65

Question 9

Management for abdominal aortic aneurysm

Answer 9

1. A-E assessment
2. US to assess diameter
   - Asymptomatic aneurysms smaller than 5.5cm → observe
   - Rapidly enlarging aneurysms (>1cm/year) of any size should be repaired even if asymptomatic
3. Medical: statins, aspirin, BP management
4. Smoking, exercise, weight loss

Surgical intervention
1st: elective endovascular aortic repair (EVAR) (<2w) – emergency is only for perforated AAA
Or open aortic surgery (young patients, longer recovery time)

Question 10

Advantages and disadvantages of EVAR

Answer 10

Reduced perioperative mortality (1% vs 5%)
Reduced hospital stay time
Better cosmetic outcome

No mortality benefit ≥5 years
Significant late complications
Not better than medical tx for those unfit

Question 11

Complications of EVAR

Answer 11

Poor perfusion (MI, spinal/mesenteric ischaemia, renal failure)
Graft migration, stenosis, infection
Leakage
Distant thromboembolism (trash foot)
Aorto-enteric fistula
Death

Question 12

Complications of abdominal aortic aneurysm

Answer 12

Rupture
Distal embolization (commonly affecting digits leading to blue-toe syndrome, may result in limb ischaemia)
- Embolism (trash foot)
- Thrombus
- DVT
Fistulation
Ureteral obstruction (ureter encasement in inflammatory perianeurysmal fibrosis of unresolved aetiology
Functional gastric outlet obstruction (compression of duodenum in its fixed retroperitoneal course between aneurysmal aorta and SMA)

Question 13

Prognosis of abdominal aortic aneurysm

Answer 13

Nature course involves slow, steady growth with progression to rupture
If rupture: 90% mortality
Repair is typically deferred until the theoretical risk of rupture exceeds the estimated risk of operative mortality