Abdominal Aortic Aneurysm

Question 1

At what level does the abdominal aorta bifurcate

Answer 1

L4 (approx level of the umbilicus)

Bifurcation of the abdominal aorta into the common iliac arteries

Question 2

In which patients are abdominal aortic aneurysms most common

Answer 2

Men
Aged over 60
Smokers
Hypertensive patients
Often strong family history

Question 3

What are the indications for surgery for repair of a AAA

Answer 3

Symptomatic aneurysms
Asymptomatic aneurysms:-
Over 5.5 cm diameter OR
Increase of diameter of greater than 1cm/yr (suggesting rapidly expanding aneurysm)

UK Small Aneurysm Trial:-
If aneurysm between 4.0 and 5.5cm diameter, open surgical repair not recommended
Aneurysms over 5.5cm diameter - patient will benefit from surgery

Question 4

What symptoms might someone with an AAA present with

Answer 4

Back pain
Tenderness over the aneurysm on palpation
Distal embolic evens
Ruptured/leaked aneurysms

Question 5

What is the risk of rupture of a greater than 5.5cm aneurysm

Answer 5

10% per year

Increasing with the size of the aneurysm

Question 6

What is the operative mortality of AAA repair

Answer 6

Elective mortality is 5%
If the patient suffers a ruptured aneurysm:-
50% reach hospital alive
Of those, operative mortality is 50%

Question 7

What is most often the cause of mortality in AAA repair

Answer 7

Haemorrhage
Subsequent MI
Renal failure

Question 8

What are the surgical options for AAA

Answer 8

Endovascular AAA repair (EVAR)

Open repair

Question 9

What is the principal behind an EVAR

Answer 9

Endovascular repair using grafts placed into the abdominal aorta from the femoral artery
Performed by a vascular surgeon and a radiologist

Operative mortality lower than for open repair

Question 10

What are the complications of EVAR

Answer 10

Intraoperative:-
Local wound complications in groin
Access artery injury - thrombosis, dissection
25% operative mortality

Immediate:-
Clot formation or embolization into aortic side branches (eg. colonic, renal)
Renal/pelvic ischaemia - due to misplacement of stent graft covering side branch

Early and Late:-
Endoleaks
Stent-graft failure or migration
Limb thrombosis
Infection

Question 11

What infectious agents are associated with AAA

Answer 11

Salmonella typhi - most common
Staphylococcal infection - sometimes
Syphilitic aneurysms - consigned to history

Question 12

What is the MASS trial

Answer 12

Significantly reduced prevalence of aneursym-related death in the screened male population between 65 and 74
53% reduction

Question 13

What age do we screen for AAA

Answer 13

65

Question 14

What is the commonest way aneurysms present?

Answer 14

Incidental finding on scan for something else (e.g. prostate or renal USS)

Question 15

What is the screening programme for aneurysms in the UK?

Answer 15

65 yo men have one-off USS

Normal at this stage- very low chance of aneurysm

Question 16

What percentage of patients have an aneurysm identified on screening?

Answer 16

1%

Question 17

What are the complications of aneurysms (AAA and popliteal)?

Answer 17

Rupture
Pain in back, tender aneurysm
Embolisation- “trash foot” (AAA- embolism formed from thrombosis, small ischaemic lesions visible on foot), missing pulses in popliteal artery aneurysm
Thrombosis- acutely ischaemic leg
Pressure- DVT due to popliteal aneurysm (occludes popliteal vein)
Fistulation- abnormal and permanent connection between two epithelial surfaces e.g. aorta and IVC (aortocaval fistula)

Question 18

What percentage of patients with a AAA will also have a popliteal aneurysm?

Answer 18

10%

Question 19

What is an intra-arterial digital subtraction angiogram?

Answer 19

Needle, wire and catheter passed into artery to insert contrast into artery.
X-ray of area then taken, then dye inserted, then another x ray taken
“One x-ray subtracted from the other”- left with inside of artery visualised

Question 20

What is an intra-arterial digital subtraction angiogram used for?

Answer 20

Visualising where the normal artery is above and below an abnormality.

Not good for identifying an aneurysm or for sizing.

Question 21

What is the definition of a AAA?

Answer 21

Abnormal dilatation of the abdominal aorta to over 50% its normal diameter i.e. 3cm+

Question 22

What are the requirements for a conventional EVAR

Answer 22

The aneurysm needs a proximal neck of at least 5mm between the aneurysm and the renal arteries, that doesn’t contain a thrombus

Question 23

How would you treat an aneurysm without a suitable neck

Answer 23

Fenestrated EVAR - side branches within the graft for visceral artery extensions

*Must be custom made and are very expensive