abdominal aortic aneurysm Flashcards
what is an aneurysm?
An aneurysm is defined as an abnormal dilatation of a blood vessel by more than 50% of its normal diameter.
what is an AAA?
An abdominal aortic aneurysm (AAA) is defined as a dilatation of the abdominal aorta greater than 3cm.
what are the risk factors for AAA?
- smoking
- hypertension
- hyperlipidaemia
- FH
- male
- increasing age
NB: DM is a negative risk factor for AAA
what are some possible causes for AAA?
largely unknown
possible causes
- atherosclerosis
- trauma
- infection
- Connective tissue disease
- inflammatory disease
what are the clinical features of AAA?
usually asymptomatic and found incidentally on screening
- abdo pain
- back/ loin pain
- distal embolisation producing ischaemia
- aortoenteric fistula
on examination, a pulsatile mass can be felt in the abdomen
signs of retroperitoneal haemorrhage are rare but can be evident
how are AAA screened for ?
the national abdominal aortic aneurysm screening programme (NAAASP) offer an abdominal US scan for all men in their 65th year.
detected AAA, these en will spend 3-5 years in surveillance prior to reaching the threshold for elective AAA repair
what are the differentials for AAA?
symptomatic
- renal colic due to presence of back pain and no other symptoms
- diverticulitis
- IBD
- IBS
- GI haemorrhage
- appendicitis
- ovarian torsion
- ovarian rupture
- splenic infarctions
what investigations are done into AAA?
- USS scan initially
- once USS has confirmed diagnosis, CT scan with contrast when at threshold diameter of 5.5 cm
- this provides more anatomical details to determine stability for endovascular procedures
how are AAA managed medically?
Less than 5.5 cm can be monitored via duplex USS as surgery prior to this gives no survival benefit
- 3-4.4 cm = yearly US
- 4.5 - 5.4 cm = 3 monthly US
CV risk factors should be reduced
- smoking cessation
- improve BP control
- statin and aspirin therapy
- weight loss and exercise
when should an AAA be managed surgically?
consider if AAA >5.5cm or is expanding at >1cm per year, or if symptomatic in otherwise well patient
if patient is unfit for surgery, can leave till 6cm
what are the main surgical treatment options for AAA?
open repair = midline laparotomy or long transverse incision, exposing the aorta, and clamping the aorta proximally and the iliac arteries distally, before the segment is then removed and replaced with a prosthetic graft
endovascular repair = Introducing a graft via the femoral arteries and fixing the stent across the aneurysm. This has improved short term outcome with hospital stay and 30 day mortality, but has higher rate of aneurysm rupture and reintervention.
what is endovascular leaking?
A complication for EVAR is endovascular leak, where an incomplete seal forms around the aneurysm resulting in blood leaking around the graft.
often asymptomatic so regular surveillance (usually USS unless a complication is noted) is needed. If left untreated, the aneurysm can expand and rupture. Any aneurysm expansion following EVAR warrants investigation for endoleak.
what are the complications of an AAA?
- rupture
- retroperitoneal leak
- embolisation
- aortoduodenal fistula
what increases the risk of AAA rupture?
- smoking
- hypertension
- female gender
- risk increases exponentially with diameter of the aneurysm
how does an AAA rupture present?
- abdo pain
- back pain
- syncope
- vomiting
- haemodynamically compromised
