aneurysms and aortic dissection Flashcards
why does atherosclerosis increase the risk of aneurysms?
Atherosclerosis induced pressure or ischaemic atrophy of the underlying media, with loss of elastic tissue causing weakness resulting in aneursmal dilation
risk factors for AAA (6)
age >50yrs; male; smoking; hypertension; family history; connective tissue disorders
presentation of an AAA
usually asymptomatic; can cause pain or tenderness
what is a mycotic aneurysm
an infection in the blood vessels arising due to haematogenous spread of an infection
presentation of a ruptured AAA
abdominal pain radiating to the back; collapse; pulsatile abdominal mass; tachycardia; drop in BP (if ruptures to the front)
ruptures AAA triad
hypotension; abdominal/back pain/ pulsatile abdominal mass
presentation of AAA embolisation and what causes it
caused by part of the thrombus inside the aneurysm breaking off and emobolising; acute limb ischaemia (6 Ps) and blue toe syndrome
what is blue toe syndrome
when there is a microembolism from atherosclerotic plaques/aneurysms that results in ischaemic toes with palpable foot pulse
size of normal aorta
around 2.5cm
at what size is an AAA referred to vascular
> 5.5cm; urgent referral, to be seen within 2 weeks
what should be done with an AAA 4.5-5.5cm AAA (screening)
screen every 3-6 months
rules for driving with an AAA
can continue to drive if <6cm; must notify DVLA if 6-6.4cm; must stop driving if >6.5; if a lorry/bus driver then must notify is <5.5 and stop if >5.5
management for a small AAA (<5.5) (4)
give antiplatelet and statins (decrease CVD risk); smoking cessation; treat hypertension; increase surveillance (12mo for 3-4.5cm and 3/6mo for 4.5-5.5)
indications for AAA surgery (3)
diameter >= 5.5cm; increase in size by >1cm per year; symptomatic (indicative of rupture/emboli)
what should be checked in the AAA pre-op assessment (8)
age; comorbidities; family/patient wishes; frailty; CT aortogram; bloods; CXR/ECG/lung function test etc.; optimal cardio/resp/renal function has been obtained
why should you clamp an AAA above and below during an open repair surgery
to stop blood flow to it - there is a collateral supply to the legs which can result in back bleeding
when is an open repair done over EVAR
younger patients (lasts for longer, less risky); aneurysm not suitable for EVAR; patient unstable
complications of open repair (8)
death; bleeding; ischaemia (colon and limbs); cardiac/resp/renal failure; wound infection/dehiscene; adhesive small bowel obstruction; graft infection; aorto-enteric fistula
what is trash foot
Acute lower limb ischaemia following aortic surgery
what is an aorto-enteric fistula
when a fistula between the small bowel and the aorta occurs allowing bleeding from the aorta into the bowel - life threatening
what must be considered anatomically for an EVAR (6)
infra renal neck - length (1.5cm min), diameter (30mm max), shape, angulation; iliac access - patency, tortuosity, diameter
pros of an EVAR
keyhole - less time in hospital, safer
complications of an EVAR (5)
contrast/radiation toxicity; wound haemotoma/infection; damage to access vessel; high reintervention rate (due to slipping, knotting, thrombosis, endoleak etc.); life long surveillance required
what are endoleaks
blood flowing outside the stent graft but inside the aneurysm sack - may spontaneous seal or may rupture
what is the worst type of endoleak?
endoleak 1
what is a type 1 endoleak?
when there is a poor seal between the graft neck and the iliacs; it is rare but high risk (bc high pressure) and prone to rupture so usually treated
what is a type 2 endoleak?
back bleeding lumbar arteries/IMA; common but low risk as it is low pressured; kept under surveillance - concerning if sack expanding; may resolve spontaneously
how many lumbar arteries are there and why might there be an endoleak
4 arteries; they may already be occluded and so blood may flow into the low pressure sac instead
Open repair vs EVAR (5 each)
OR - higher early mortality, HDU bed, longer hospital stay/recovery, lasts longer, less expensive; EVAR - lower early mortality, ward bed, shorter hospital stay/recovery, higher mortality rate, more expensive
what is permissive hypotension
maintaining a low blood pressure after trauma (one that the body has stabilised itself) in order to prevent bleeding out as a result of higher BP - don’t give fluids
management of ruptured AAA (6)
bloods (FBC, U&Es, LFT, glucose, clotting and cross matching for transfusion etc.); ECG; Large bore IV + catheter; fluid resuscitation (permissive hypotension 70-90); assess age/comorbidities/functional status etc.; CT to diagnose anatomical EVAR suitability
wilson and junger
criteria for screening disease
national AAA screening program criteria
offered to men >= 65yrs; is <3cm then discharged, 3-5.5 then enrolled for further screening; >=5.5 referred to vascular (within 2 weeks)
pathophysiology of aortic dissection
tear in intima -> flowing blood enters and dissects through the media -> intimal flap, false lumen and re-entry tear occurs
types or aortic dissection
type A - proximal to the L subclavian and involved the ascending aorta, more severe; type B - distal to L subclavian and involves the descending aorta
aortic dissection epidemiology
men x3 more likely; people aged 50-65 (if under 40 likely to have a CT disease);
risk factors for aortic dissection (10)
hypertension; atherosclerosis; aortic aneurysm; bicuspid aortic valve; coarctation; FH; CT disorder; pregnancy; cocaine use; high intensity weight lifting
presentation of aortic dissection (7)
tearing chest pain radiating to back; collapse; pulse deficits; radial-radial/ radial-femoral delay; difference >20mmHg between arms; new aortic regurgitation murmur; neurological signs of stroke/ paraplegia
aortic dissection investigation (3 - 2,1,3)
CXR - widened mediastinum, pleural effusion/haemothorax; ECG - Mi mimic due to ischaemic changes if coronary arteries mal perfused; CT angiogram - intimal flap, true/false lumen, branch vessel perfusion
what is the definitive investigation for an aortic dissection
CT angiogram
complications of aortic dissection (3)
malperfusion; rupture; aneurysmal dilation
malperfusion of different organs…
coronary - MI; carotid - stroke; spinal - paraplegia; renal - renal failure; mesenteric - acute mesenteric ischaemia; limb - acute limb ischaemia
management of type A aortic dissection
open repair to replace aortic arch/valve; may require reimplantation of coronary/great arteries
management of type B dissection
uncomplicated - management of BP using IV labetalol, analgesia, surveillance; complicated (malperfusion, fluctuating BP etc.) - TEVAR (Thoracic endovascular repair) to cover entry tear and promote thrombosis of false lumen
what is an aneurysm
localised dilation of an artery with >50% increase in diameter (otherwise called ectasia)
true vs false aneurysm
true - involves all 3 walls, fusiform or saccular in shape; false - hole in arterial wall, pulsatile haematoma contained by externa
where are false aneurysms likely to occur
radial; femoral; anastomotic
what is a type 3 endoleak
poor seal between graft compnents
what is a type 4 endoleak
porosity of the graft
what is a type 5 endoleak
‘endotension’; sac expansion with no demonstrable endoleak
when is a popliteal aneurysm indicative for surgery?
diameter >2-3cm; significant lining thrombus; symptomatic (DVT, PE, ALI etc.)
treatment for popliteal aneurysm
stent grafting; thrombolysis (may clear vessels to allow for stenting); exclusion bypass surgery
treatment for popliteal aneurysm
stent grafting; thrombolysis (may clear vessels to allow for stenting)
treatment of radial/femoral aneurysm
spontaneous thrombus; US guided compression; thrombin injection; surgery
how to popliteal aneurysms present?
ALI due to thrombosis; chronic limb ischaemia; CVT due to compression of popliteal vein
