Abdominal Aoritc Aneurysm Flashcards
What is an aneurysm?
https://www.youtube.com/watch?v=FgcHtmry3iA
A localized, blood-filled balloon-like bulge in the wall of a blood vessel. The arteries most frequently involved are the abdominal aorta, iliac, popliteal, femoral artery and thoracic aorta (in decreasing frequency)
What are the different types of aneurysms?
- True aneurysm
- False aneurysm
What is a true aneurysm?
One that involves all three layers of the wall of an artery (intima, media and adventitia).
True aneurysms include atherosclerotic, syphilitic, and congenital aneurysms, as well as ventricular aneurysms that follow transmural myocardial infarctions (aneurysms that involve all layers of the attenuated wall of the heart are also considered true aneurysms).
What are the subtypes of true aneurysms?
- Fusiform
- Saccular
What is the difference between a fusiform and saccular true aneurysm?
The more common fusiform-shaped aneurysm bulges or balloons out on all sides of the blood vessel. A saccular-shaped aneurysm bulges or balloons out only on one side.
What disease processes are true aneurysms associated with?
- Hypertension
- Atherosclerosis
- Smoking
- Collagen abnormalities - e.g. Marfan’s, Ehler-Danlos
- Trauma
- Infection - syphilis, E. coli, Salmonella
What is a pseudo-aneurysm?
A collection of blood leaking completely out of an artery or vein, but confined next to the vessel by the surrounding tissue. Therefore, the surrounding tissues form the wall of the aneurysm, not the walls of the vessel. This blood-filled cavity will eventually either thrombose (clot) enough to seal the leak, or rupture out of the surrounding tissue.
What is the most common location for a AAA to occur?
Infrarenal - 95%
Which sex do AAA’s occur in more commonly?
Males
When does aortic dilation become classified as an aneurysm?
Exceeds 3.0 cm
or
Increases by 50% of normal circumference
What are the common sites for AAA’s to occur?
- Aorta
- Iliac artery
- Femoral Artery
- Popliteal artery
What are complications of AAA’s?
- Rupture
- Thrombosis/Embolism
- Fistulae
- Pressure on other structures
How would someone with an unruptured AAA present?
Asymptomatically - often discovered incidentally
If symptomatic:
- Central abdominal pain/back pain
- Distal embolic events - due to aneurysmal emboli formation
- Evidence of aortic occlusion - due to thrombus formation
How would someone with a ruptured AAA present?
- Intermittent/continuous abdominal pain - radiates to the back, iliac fossa or groins
- Collapse/Shock - hypovolaemic
- Expansile abdominal mass
What might you see on an abdominal examination in someone with an AAA?
Expansile abdominal mass
If you suspected a ruptured AAA, what investigations would you do?
- Ultrasound
- CT
- MRI
What age does screening for AAAs take place?
65 years
What threshold diameter of an aneurysm is used to determine whether endovascular repair would be beneficial?
5.5cm
What is the incremental risk of rupture for an aneurysm if it is less than 5.5cm?
1% per year
What is the incremental risk of rupture if an aneurysm is above 6.0cm?
10% per year
What factors increase the risk of an aneurysm rupturing?
- HTN
- Smoking
- Female
- Strong FH
Why is operating on an aneurysm <5.5 cm not advisable?
You risk doing more harm than good to the patient.
When assessing an individuals fitness for surgery for a AAA, what Pre-operative investigations would you perform?
Anaesthetic Work up
- Routine bloods
- ECG, Echo, cardiac perfusion scan
- CXR, PFTs
- CT abdomen - assess anatomy
What is the risk of operative mortality for open surgery on a AAA?
Approximately 5%
What are complications of open surgery on a AAA?
- Spinal/visceral ischaemia
- Haemorrhage
- Aorto-duodenal fistula
- Infected graft
What non-operative measures would you take for someone with an unruptured AAA?
- Control of hypertension
- Stop smoking
- Lipid-lowering medication - statins
Why is ultrasound used as part of AAA screening programmes?
CT Abdomen is not suitable for AAA screening programs because of radiation exposure and cost.
If an individual had a AAA <5.5cm, how would you manage them?
Modify risk factors - HTN, Smoking, lipid lowering
What are the typical causes of Arterial aneurysms?
Atheroma
Trauma
Infection
Connective tissue disorders
Inflammatory - takayasu’s aortitis
If someone had a AAA >5.5 cm, how would you manage them?
Manage risk factors
Assess for either:
- Endovascular repair
- Open repair
What is an EVAR?
Endovascular Aortic repair
Involves placing a stent graft inside the aneurysm via a femoral arteriotomy.
http://www.vascularinfo.co.uk/aortic-aneurysm-surgery/endovascular-aneurysm-stent-repair-evar/
What is involved in open repair of an abdominal aortic aneurysm?
Making a cut in the belly in order to get to the aneurysm and sewing in an artificial artery (graft) into the normal artery just above where the aneurysm starts and into the normal artery just below where it finishes.
What type of graft(s) is/are used in an open surgical repair of a AAA?
- Dacron
- Gore-Tex
What are disadvantages of EVAR?
- “Endoleak”
- Fragmention of device
- Migration of endovascular stent
- Long term follow-up required
- Increased complication rate
- Increased post-op intervention rate
What is the difference in terms of follow up between an open repair and a EVAR insertion?
Open repair only needs a few clinics and then can be sent on their merry way, whereas EVAR requires long term follow up
What is endoleak?
Sac not excluded from circulation (still have blood going into the aneurysm sac). This means there is a continuing risk of rupture if endoleak develops.
How would you manage a ruptured AAA?
- ABCDE
- Call vascular surgeon - warn them
- ECG
- Bloods - amylase, Hb, crossmatch
- IV access
