Aneurysm Flashcards
What is an aneurysm
Localised dilatation of an artery with a permanent diameter that is 1.5x its usual size
What is a true aneurysm
wall of the artery forms aneurysm
What is a false aneurysm
Other surrounding tissue forms the wall of the aneurysm (small hole in the blood vessel wall allows blood to leak out and pool)
What are the two types of true aneurysms
Fisuform- artery wall balloons out symmetrically
Saccular (berry)- Where artery wall only balloons out on one side (possibly due to weakening of that artery wall)
Why does an aneurysm occur
1) Due to weakening of blood vessel wall
2) When weakened, BV can’t contain pressure of blood so it dilates (aneurysm)
3) When pressure increases, there is further dilatation of BV wall
4) When the diameter of the vessel lumen increases, the pressure flowing through it increases
5) Leads to a positive feedback loop of continuous bulging of arterial wall so aneurysm gets bigger
6) Therefore as pressure increases, diameter increases which causes further increase in BP
Where do most aneurysms occur
Aorta
Abdo aorta most common
–>Mostly below the point where renal arteries branch out of AA
Risk factors for aneurysms
Hypertension Smoking Male + >60yo Diabetes High LDL levels Pregnancy Coarcation of aorta
What genetic disorders are risk factors for
Marfan’s syndrome - fibrillin and other elastic properties are impaired causing weak blood vessel walls
Ehlers Danlos syndrome -Abolity to form collagen is disrupted
Complications of an aneurysm
Compressing nearby structures such as IVC
Rupture
Effect of thoracic aneurysm near aortic valve
Prevents valve from shutting properly meaning back flow of blood into left ventricle during diastole
What is Grey-Turner’s sign
AAA rupture causes blood to flow into retroperitoneal space. Causes a purple discolouration in the flanks
Signs and symptoms of a ruptured aneurysm
Hypotension Collapse Tachycardia Syncope Vimiting Shock Anaemia severe pain in left flank Expansile mass in abdomen
Aneurysm investigations
Abdo ultrasound to stage and locate
CT angiography- to see if compressing other structures or potential for rupture
Management of aneurysm
A-E assessment (ECG, analgesia, inform ITU of potential admission)
Bloods and crossmatch
Imaging (USS to check size and if rupture)
ICU
Fluids (fluid boluses to increase BP then maintenance fluid)
Surgery (EVAR or open surgery)
Major haemorrhage protocol (if signs of acute haemorrhage with significant blood loss)
Vascular team
What are the options for surgery for a ruptured aneurysm
EVAR (end-vascular aneurysm repair)
Open surgery
Whats an EVAR
aortic graft transmitted through femoral artery into abdo aorta
When would you offer surgery for aneurysm if unruptured
Symptomatic
or
asymptomatic and >5.5cm
or asymptomatic, larger than 4cm and has grown by more than 1cm in 1 year
What is aneurysm surveillance
All men >66yo are screened nationally by USS. If they have risk factors, they are at an increased risk of developing aneurysms so these patients also require surveillance
Risk factors: COPD Coronary, cerebrovascular or peripheral arterial disease European family origin family history of AAA Hyperlipidaemia Hypertension Smoking history
Reduce risk of rupture by modifying behaviours and diseases
Presentations of popliteal aneurysm
Asymptomatic
- If chronic, can exhibit mass symptoms on nearby structures such as tibial nerve which can cause leg pain and paraesthesia
- Can have compression of popliteal vein which can lead to leg swelling
Popliteal aneurysm thrombosis presentation
Lower extremity ischaemia causing:
-LEg pain, paraesthesia, pallor and cold legs
Investigations for popliteal aneurysm
Duplex USS scan (screening and diagnostic)
CT or MR angiography (can measure true lumen diameters)
management of popliteal aneurysm
Conservatively if <2cm and continue with surveillance
Surgical- EVAR, Open
What is aortic dissection
Where inner layer of aorta tears (intima) tears. Causes blood to surge through the tear causing inner and middle layers (media) to separate
Creates new false lumen which can lead to a rupture
Where do dissections usually occur
In first 10cm of thoracic aorta
What can weakening of aorta lead to
Aneurysm or a dissection
