Aortic aneurysm (CV)

Question 1

Define abdominal aortic aneurysm (AAA).

Answer 1

Permanent pathological dilation of the aorta with a diameter >1.5x (or >3cm) expected anteroposterior diameter of that segment, given the patient’s sex and body size

Question 2

Describe the pathophysiology of AAA.

Answer 2

• primary event is loss of the intima with loss of fibres from the media
  
  • associated with and potentiated by increased proteolytic activity and lymphocytic infiltration
• aneurysms typically represent dilatation of all layers of the arterial wall

Question 3

Where do the majority of AAAs occur?

Answer 3

Below the renal arteries (infrarenal)

Question 4

What is the difference between a true aneurysm vs a pseudoaneurysm?

Answer 4

• a true aneurysm is abnormal dilatation involving all layers of the arterial wall - these can be fusiform (most AAAs) or sac-like
• false aneurysms (pseudoaneurysms) involve a collection of blood in the outer layer only (adventitia) which communicates with the lumen e.g. after trauma

Question 5

What is the difference between unruptured and ruptured AAAs?

Answer 5

• unruptured aneurysms occur due to degeneration of elastic lamellae and smooth muscle loss
• ruptured AAAs can leak into retroperitoneal space (relatively haemodynamically stable) or intraperitoneal space (likely to result in shock)

Question 6

Which groups does AAA affect most? (2)

Answer 6

• M>F
• 60-70 years old

Question 7

What is the screening population for AAA?

Answer 7

Males >65 years - single USS done at 65

Question 8

What are the clinical features of an unruptured AAA?

Answer 8

• ASYMPTOMATIC
• usually an incidental finding on USS or CT
• may have pain in back, abdomen, loin or groin

Question 9

What are the clinical features of a ruptured AAA?

Answer 9

• life-threatening
• severe, central abdominal pain radiating to the back(/iliac fossae/groin)
• palpable pulsative + expansile abdominal mass
• shock - hypotension + tachycardia
• syncope

Question 10

What might you see on examination in ruptured AAA? (7)

Answer 10

• pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta
• abdominal bruit
• Grey-Turner’s sign (retroperitoneal haemorrhage)
• hypotension + tachycardia (shock)
• loss of consciousness
• pallor
• embolic phenomena - lower leg purpura

Question 11

What is the most important risk factor for AAA?

Answer 11

Smoking

Question 12

What are some risk factors for AAA? (7)

Answer 12

• smoking
• Fx
• increased age (60-70)
• male
• connective tissue disorder (Marfan syndrome)
• atherosclerosis
• hypercholesterolaemia

Question 13

What is the first-line investigation for AAA?

Answer 13

Aortic ultrasound

Question 14

What should you not do while waiting for aortic ultrasound results for AAA?

Answer 14

Do not delay diagnosis and management of a ruptured AAA while waiting because imaging does not tell you that AAA is ruptured

Question 15

When do we do a CT angiogram for AAA?

Answer 15

Only in haemodynamically stable patients to visualise ruptured AAA

Question 16

Who is ultrasound screening offered to for AAA?

Answer 16

All men >65 in UK to determine diameter of abdominal aorta

Question 17

What bloods can be done for AAA? (5)

Answer 17

• FBC
• clotting screen
• renal function
• LFTs
• ESR & CRP

Question 18

What imaging modalities can be used for AAA? (4)

Answer 18

• aortic ultrasound - 1st line
• CT angiogram - to visualise ruptured AAA in haemodynamically stable
• CT with contrast - show whether aneurysm has ruptured
• MRI angiography

Question 19

What are some differential diagnoses for AAA? (8)

Answer 19

• diverticulitis - constipation, LLQ pain, leukocytosis
• ureteric colic - loin–>groin
• IBS - flares lasting 2-4 days
• IBD
• appendicitis
• ovarian torsion
• GI haemorrhage
• mesenteric artery aneurysms/acute occlusion

Question 20

What is the management plan for unruptured AAA?

Answer 20

Regular ultrasound surveillance + aggressive cardiovascular risk management (smoking cessation, antiplatelet therapy with aspirin, statins, antihypertensives, lifestyle)

Question 21

How often should you repeat ultrasound for AAA of different sizes?

Answer 21

• if small AAA (3-4.4cm) - offered yearly repeat US
• if medium AAA (4.5-5.4cm) - offered repeat ultrasound every 3 months
• if large AAA (>5.5cm) or symptomatic - elective surgery generally recommended (refer within 2 weeks)

Question 22

When do you do surgical management of an aortic aneurysm? (3)

Answer 22

• ruptured (or symptomatic) - emergency surgery
• > /=5.5cm
• rapidly enlarging (>1cm/year)

Question 23

What is the surgical management plan for ruptured AAA? (6)

Answer 23

• open surgical repair or EVAR (endovascular aneurysm repair)
• resuscitation measures (oxygen, IV access, arterial and urinary catheter, FFP)
• perioperative Abx
• analgesia
• VTE prophylaxis (enoxaparin/heparin)
• IV fluids (saline or Hartmann’s solution)

Question 24

What are some complications of AAA? (10)

Answer 24

• abdominal compartment syndrome
• ileus, intestinal obstruction and ischaemic colitis
• AKI
• post-implantation syndrome
• amputation due to limb ischaemia
• spinal cord ischaemia
• impaired sexual function
• anastomotic pseudoaneurysm
• aortic neck dilation
• graft infection

Question 25

Name a complication of EVAR (AAA surgery).

Answer 25

• endo-leak if the stent fails to exclude blood from aneurysm (persistent blood flow outside graft and within aneurysm sac after EVAR)
• presents without symptoms on routine follow-up

Question 26

What is the prognosis of a ruptured AAA?

Answer 26

Patients will not survive to reach theatre (very poor)