AAA

Question 1

definition of AAA

Answer 1

>3cm across

an aneurysm is a permanent localised dilation of an artery at least >1.5 times original vessel diameter, if less than this it is ectasia, not an aneurysm

most AAA are fusiform (rugby ball shape)

Question 2

true aneurysms

Answer 2

dilatation of all layers of the arterial wall

can be degenerative (atherosclerotic)

secondary to connective tissue problem eg Marfans

post-dissection - thoracic/Type B

infection - salmonella or syphilitic

inflammatory - takayasus, PAN

congenital

Question 3

false aneurysms

Answer 3

collection of blood in outer layer only (adventitia) which communicates with lumen eg after trauma

usually iatrogenic or traumatic

connective tissue wall

post-haematoma

Question 4

pseudoaneurysms

Answer 4

defect in part of wall of artery and the blood pools under the remaining 2 layers of the wall

Question 5

thoracoabdominal aortic aneurysm

Answer 5

varying types

can go from the L subclavian artery (and sometimes over arch) all the way down to iliacs

treated by thoracolaparotomy - cut between shoulder blades

lose 5l blood/min - high mortality

risk of paraplegia because risk of lack of blood supply to intercostal arteries and so spinal cord

Question 6

aetiology of AAA

Answer 6

degeneration of elastic lamellae and smooth muscle loss

genetic component

most result from a degenerative process

some from a connective tissue disease - marfan’s, ehlers-danlos type IV

95% due to atherosclerosis

inflammatory (variant of atherosclerotic aneurysms eg Takayasu’s aortitis)

traumatic

infective (mycotic in endocarditis, tertiary syphilis - especially thoracic aneurysms)

Question 7

RF for AAA

Answer 7

HTN

smoking

FH

Question 8

epidemiology of AAA

Answer 8

• 3% >50yrs
• 5% of the population
• >60 years and 15%>80 years will have an AAA.

male more than female - most common in elderly men

less common in diabetics

most result from a degenerative process

Question 9

sx of AAA

Answer 9

asx

may cause epigastric/back pain - often discovered incidentally

other distributions of pain:

• central abdominal pain
• epigastric pain
• flank pain
• R iliac fossa pain
• L iliac fossa pain
• loin to groin pain
• (Can cause pain virtually anywhere in the abdomen – even mimic other conditions eg renal calculi, An elderly male with loin to groin pain who has never had stones before is more likely to have AAA)

Can present with thromboembolic events – affecting one or both lower limbs

symptoms by pressure effect or vessel rupture occasionally with fistula formation or they may be a source of emboli

lower limb purpura - small emboli from the aneurysm

compression = sciatica, leg swelling, hydronephrosis

fistulation (abnormal communication between aorta and another hollow fistula - bad news) - aorto-duodenal, aorto-caval

distal embolism - atheroma break off

Question 10

sx of ruptured AAA

Answer 10

surgical emergency presenting with epigastric pain radiating to the back and hypovolaemic shock

In itself backpain doesn’t suggest rupture (could be just pressure of the aneurysm on the lumbar spine) but acute onset means it needs to be ruled out

lightheadedness suggests reduced cerebral perfusion - due to hypovolaemic shock and sweating is a sympathetic response to this

Question 11

emergency presentation of AAA

Answer 11

epigastric/back pain ranging from vague discomfort to excruciating pain,

or collapse associated with leakage/rupture.

Rarely, present with GI bleeding due to erosion into the duodenum

or high output cardiac failure due to aortocaval fistula

Question 12

signs of AAA

Answer 12

pulsating mass on an abdominal examination - ABOVE THE UMBILICUS (ABDOMINAL AORTA BIFURCATES AT L4 - UMBILICUS)

if expansile mass is felt below likely iliac aneurysm

If leaking or rupture, abdominal and back tenderness with pallor, tachycardia, hypotension and hypovolaemic shock.

Question 13

Ix for AAA

Answer 13

CT evaluates the aorta and the retroperitoneum acutely - only indicated in haemodynamically stable patients when diagnosis is in doubt. Quick, reliable confirms diagnosis gives extent of aneurysm and the size of the teflon graft that is needed. Important to know if renal/iliac arteries are involved

if no evidence of leak the CT scan is useful to look for other pathologies, calcification and thrombus

if pt is bleeding actively = theatre for repair

present with calcifications on a plane X-Ray

diagnosis by US or CT

bloods

arteriography/MRA - measure involvement of renal arteries

Question 14

bloods for AAA

Answer 14

FBC,

UE,

clotting,

crossmatch blood in acute presentation