Arterial Occlusive Disease Flashcards
What are the crural vessels?
three vessels that run below knee
Posterior Tibial Artery
Anterior Tibial Artery
Peroneal Artery
Meaning of ischaemia?
lack of oxygenated blood supply to part of the body- leading to anaerobic respiration
Meaning of thrombus?
blood clot that forms in situ ( for e.g. at site of plaque rupture)
Meaning of embolus?
blood clot that travels to a different site (distal)
meaning of atherosclerosis?
build up of plaque (atheroma) inside arteries
described as narrow and hardening of blood vessels
What does peripheral arterial disease refer to?
arteries only
What does peripheral vascular disease relate to?
describes any circulatory disorders- including venous and lymphatic systems
Likely diagnosis for worsening pain in left leg on exertion, smoker and hypertension?
intermittent claudication
Pathophysiology of intermittent claudication?
atherosclerosis causes areas within arteries (supplying the legs) to become narrowed over time.
narrowed arteries cannot supply blood quickly enough when demand is high and this leads to anaerobic respiration and release of painful metabolites.
What diseases could corelate with patients describing cramping pain in one or both calves?
corelates with disease in UPSTREAM blood vessels
for e.g. femoral or popliteal arteries
What diseases could corelate with patients describing cramp in buttocks, thighs and erectile dysfunction?
distal aorta or iliac arteries affected
Differential diagnosis for exertional leg pain?
osteoarthritis - pain comes on after variable amount of exercise
neurogenic (impingement of nerves exiting spinal foramen) - relived by bending over
venous- patients with history of proximal DVT (deep vein thrombosis) can suffer from pain in leg or legs due to impaired venous return but relived by elevation of leg
Risk factors for PAD? Peripheral arterial disease
smoking
hypertension
diabetes
and dislipodaemia
Examination for PAD?
lose hair from legs and feet
shiny skin appearance
slow growing and brittle toenails
cooler and paler skin
What would we feel for in PAD?
Examine for presence or absence of peripheral pulses i.e femoral, politeal , posterior tibial and dorsalis pedis (comparing sides)
Results from using a hand held doppler?
Normal = triphasic waveform (systole, diastole, recoil)
ie: three sounds
Abnormal = biphasic or monophasic waveform (loss of recoil)
ie: two sounds or single ‘woosh’
or absent
Where are primary areas to check blood flow in peripheral arteries?
Dorsalis Pedis Artery (DPA): Located on the top of the foot.
Posterior Tibial Artery (PTA): Found behind the ankle, slightly to the inside of the Achilles tendon. These are primary areas to check for blood flow in the lower extremities.
What does ankle brachial pressure index involve?
measuring systolic blood pressure in arm and leg and dividing one by the other
What do ABPI results mean?
normal ABPI- between 0.8-1.3
ABPI less than 0.5- indicates severe arterial disease
ABPI > 1.3- reflects arterial calcification
Management of intermittent claudication?
secondary prevention
Modify risk factors and manage cardiovascular risk
1. Medications (antiplatelet, statin)
2. Smoking cessation*
3. BP control*
4. Good glycaemic control*
exercise
Improve collateral circulation improve pain-free walking distance
- Self-directed: can encourage to record daily step count/measurable distance ie: number of lampposts
- Supervised – not available in all areas
Pathophysiology of critical limb threatening ischaemia?
progressive atherosclerosis causes severe narrowing or complete occlusion in arteries
even without gravity, supply cannot match demand even at rest
anaerobic metabolites releases- leads to pain
Patients keep leg(s) hanging down -oedema - skin breakdown/ulceration which doesn’t heal
Symptoms of critical limb threatening ischaemia?
rest pain and/ or tissue loss
Describe buergers test?
Another test to assess peripheral blood supply
- Elevate leg >45 degrees and hold
- in critical limb threating ischaemia have feet becoming pale and see veins empty (venous guttering) - Patient sits with leg dependant (legs dangling over bed)
-foot appears red (sunset foot)
Initial management of CLTI?
Full blood count (FBC)
Urea and electrolytes (U&Es)
Coagulation
G&S (incase blood transfusion required)
ECG
Antiplatelet, statin
Analgesia- relief of pain
DVT prophylaxis - prevention of DVT
+/- Antibiotics- infection in ulcer
CT angiogram of lower limbs
ECHO and pulmoanry function tests
Why should patients with peripheral arterial disease never have TEDS? (Compression stockings)
could further compromise the peripheral blood supply
instead should have a small dose of an injectable blood thinner
Decision making factors in vascular surgery?
Pattern of disease
- symptoms
- imaging
Complexity
- previous surgeries
- operative plan
Conduit
- vein vs prosthetic
- quality, length
Operative risk
- co-morbidities
- tests of fitness
- frailty
- previous level of function
- anaesthetic risks
- recovery
Patient wishes
- shared decision making
Different types of operative management?
conservative/ palliative-Symptom management
endovascular intervention -Angioplasty
+/- stent
open surgery -Endarterectomy
Bypass
Amputation*
hybrid procedure-eg: endarterectomy and stent
When might amputation be required?
Amputation may be required if there is no revascularisation option, or if this is not successful
Describe endovascular interventions?
use wires and balloons to open up narrowed blood vessels-angioplasty
- Stent can then be deployed to reduce risk of re-stenosis
Best outcomes for focal lesions
Can be day case under local anaesthetic
Disadvantages of endovascular interventions?
Potential to make blood supply worse – dissection, distal embolisation etc
- Longevity of any improvement variable
- Caution in patients with poor renal function
What are the different operations involving open arterial surgery?
bypass -additional channel for blood to flow
endarterectomy- clearing out plaque from inside of blood vessel. Clamp vessels above and below
Names of bypass operations?
fem-pop bypass: go from either common femoral or superficial femoral artery to the popliteal artery
ax-fem or ax-bifem will gofrom axillary artery to one or both femoral arteries
What is a conduit?
carries the blood for bypass
either vein (preferred) or prosthetic tube
Why is a vein a preferred conduit?
better long term patency
reduced rates of infection
Challenges of open surgery?
significant blood loss, risk of major amputation or death
long hospital stay and post operative recovery
Likely diagnosis for “ painful,cold,pale right arm , unable to move fingers, can’t feel pulses. Was on warfarin for AF but was stopped”
acute limb aschaemia
What are the 6 P’s of acute limb ischaemia?
(also present in CLTI)
pain
pallor
pulseless
perishingly cold
(late signs)
paraesthesia
paralysis
Pathophysiology of acute limb ischaemia?
Sudden blockage to blood flow in a normal artery
leads to
ischaemia
leads to cell death (necrosis)
Clinical appearance of acute limb ischaemia?
Acute arterial spasm - pallor
Deoxygenated blood fills skin - mottling
Stagnant blood coagulated - fixed staining (irreversible ischaemia)
What will an attempt to revascularise the limb lead to?
release lots of metabolites
(potassium, myoglobin and hydrogen ions) into systemic circulation and leading to acidosis , acute kidney injury, cardiac instability and potentially death
What does tenderness of muscle on palpation signal?
indicates the limb is threatened
Acute vs acute-on -chronic limb ischaemia?
similarities
-sudden change in symptoms
disimilarities
-acute limb ischaemia changes happen quicker. on chronic have developed alternative routes for blood flow.
-common aetiology of on chronic limb ischaemia is thrombosis in situ as a result of atherosclerotic plaque rupture. Also occur if there is an intervention to improve blood supply (such as stent, bypass graft) - which then blocks
-in contrast, acute limb ischaemia usually occurs as a result of embolus- which lodges as a place where blood vessels divide (left atrium with conditions that cause turbulent blood flow)
Non cardiac causes include coagulation disorders and malignancy (predisposition to clot formation).
Initial management of ALI?
start an intravenous blood thinner- heparin (reduces propagation of the clot)
blood tests
Full blood count (FBC)
Urea and electrolytes (U&Es)
Coagulopathy screen( if unsure of precipitating factor)- before anticoagulants
G&S (for blood transfusion)
ECG (24 hour tape)
ECHO (to look for clots in heart)
CT angiogram to confirm diagnosis and help plan the intervention
What is the most common operation for acute limb ischaemia and give features?
embolectomy
can do under general anaesthetic, regional block or even local anaesthetic
make a cut above and below the clot (control with clamps)
make small opening in front wall of the artery- which allows us to pass a small plastic tube called a Fogarty catheter up beyond the clot
at the end there is a small balloon which can pull clot through hole made.
Post embolectomy actions?
If unsuccessful - amputation or palliation
Consider need for fasciotomies
Anticoagulation
Further investigations for underlying cause if not already known
What is compartment syndrome?
increased pressure within a closed osteofascial compartment, resulting in impaired local circulation.
Without prompt treatment, acute compartment syndrome can lead to ischemia and eventually, necrosis.
What is an endarterectomy?
surgical operations to clear out the atherosclerotic plaque from the inside of an artery
Which patients would be considered for a carotid endarterectomy?
- symptomatic carotid stenosis
- > 50% ICA stenosis on US
- good neurological recovery
- within 2 weeks from event
why is CEA not offered to patients with ongoing and profound neurological impairment ?
To reduce the risk of further neurological impairment from
an embolic carotid plaque
Studies show future stroke risk reduction greater than with
medical management alone
However, CEA will not improve current neurology (symptoms)
Risks of carotid endarterecetomy?
stroke around time of operation
damage to other structures (numbness along jaw line, facial droop, tongue deviation, changes to voice
How does blood get to the brain during carotid endarterectomy?
Brain perfusion reliant on complete Circle of Willis, with supply from contralateral carotid artery and vertebral arteries OR shunt can be used
