Vascular: AAA

Question 1

Outline the pathophysiology of a AAA

Answer 1

Dilatation of a blood vessel by more than 50% of its normal diameter

AAA = dilation >3cm

Question 2

Outline the aetiology of a AAA

Answer 2

Unknown

Possible = atherosclerosis, trauma, infection, connective tissue disease (e.g. Marfan’s disease, Ehler’s Danlos, Loey Dietz), or inflammatory disease (e.g. Takayasu’s aortitis)

Question 3

What are the symptoms of a AAA?

Answer 3

Asymptomatic, incidental finding

Abdominal pain, radiating to back or loin pain

Distal embolisation producing limb ischaemia

Aortoenteric fistula

Ruptured = tearing pain, shock, syncope, vomiting

Question 4

What investigations should be done for a AAA?

Answer 4

O/E = abdominal pulsatile mass above umbilical level, rare signs of retroperitoneal haemorrhage

G+S, cross match

USS

CT contrast

Question 5

Who is screened for a AAA?

Answer 5

Male 65 = abdo US

Question 6

How should a AAA be managed?

Answer 6

3. 0-4.4 cm = yearly ultrasound
4. 5-5.4 cm = 3-monthly ultrasound

Smoking cessation (reduces rate of expansion and risk of rupture)

Improve blood pressure control

Statin and aspirin therapy

Weight loss and increased exercise

Surgical (>5/5.5cm, expanding at >1cm/year, symptomatic)

1. Open repair = incision exposing aorta, clamping proximally and the iliac arteries distally, segment removed, replaced with prosthetic graft
2. Endovascular repair = graft via femoral arteries, fixing stent across aneurysm

Question 7

Outline the complications of a AAA

Answer 7

Endovascular leaking = incomplete seal forms around the aneurysm resulting in blood leaking around the graft

Rupture

Retroperitoneal leak

Embolisation – distal limb ischaemia

Aortoduodenal fistula

Question 8

What is the management if a AAA ruptures?

Answer 8

NBM

High flow O2

IV access (2x large bore cannulae), IV fluids, catheter

Urgent bloods = FBC, U+Es, clotting, lactate, crossmatch for minimum 6 units

Aim to keep BP <100 = permissible hypotension (raising BP will dislodge and clot and precipitate further bleeding)

FAST scan - fluid in pelvis, around liver/spleen, CT angio if unsure

Transfer to local vascular unit

Pt unstable = immediate transfer to theatre for open surgical repair

Pt stable = CT angiogram, determine whether the aneurysm is suitable for endovascular repair

Question 9

Describe the different types of endovascular leaks

Answer 9

1 = at graft ends due to inadequate seal

2 = filling from branch vessels

3 = defect in graft fabric

4 = graft porous

5 = expansion without demonstrable leak

Question 10

What are the associated risk factors for a AAA?

Answer 10

Smoking

HTN

Hyperlipidaemia

FH

Male

Increasing age