Peripheral Artery Disease Flashcards
What is peripheral artery disease?
Obstruction of large arteries of systemic vascular system NOT including coronary or cerebral circulation which leads to reduced blood supply to these areas (LL usually affected)
What is atherosclerosis? How is it different to arteriosclerosis?
Atheroma (fatty deposits on artery walls) and hardening/stiffening of blood vessel walls which affected medium and large vessels and narrows lumen
Arteriosclerosis is when there is only stiffening of arterial walls due to loss of elasticity
What are the consequences of atheromatous plaques?
Hypertension and strain on heart due to increased resistance caused by stiffened BV walls
Stenosis= reduced blood flow
Thrombus formation due to plaque rupturing which can lead to ischaemia
What are the risk factors for atherosclerosis?
Non-modifiable:
- older age
- family history
- male
Modifiable:
- smoking
- alcohol consumption
- diet high in sugar and trans-fats i.e. poor diabetic control and hyperlipidaemia
- low exercise
- obesity
- poor sleep
- stress
Which medical conditions can increase the risk of developing atherosclerosis?
Diabetes Hypertension Chronic kidney disease RA Atypical antipsychotic medication
What is the difference between acute, chronic and critical limb ischaemia?
Acute= rapid onset of ischaemia due to thrombus blocking artery
Chronic= narrowing of arteries leading to reduced blood flow but not complete occlusion. Associated with collateralisation
Critical= end-stage of peripheral artery disease where blood supply inadequate to limb to enable normal function i.e. advanced stage of chronic limb ischaemia
What are signs of critical limb ischaemia?v (6 Ps +)
What is the likely outcome if someone is presenting with these signs?
Pain (at rest) Pallor Pulseless Paralysis Paraesthesia i.e. pins and needles Perishing cold
+
- non-healing ulcers
- gangrene
Poor outcome as tissue likely to be no longer viable
What are the causes of acute limb ischaemia?
Thrombus (due to rupturing of atherosclerotic plaque)
Embolism (associated with AF)
Trauma (crushing injuries preventing blood flow)
Transaction (severing of arteries)
Dissection (prevents blood passing through true lumen)
NOTE: can be acute or acute on chronic i.e. blockage of already narrowed vessels
What are the signs and symptoms of acute limb ischaemia?
Pain disproportionate to symptoms
Decreased strength of pulse (or absent pulse if critical)
AF
Radio-radial delay or radio-femoral delay = aortic dissection/coarctation (location of coarctation determines whether R-R or R-F delay)
How can acute limb ischaemia be managed conservatively, medically and surgically?
Conservative:
-position limb at lower level
Medical:
-analgesia
- aspirin
- anti-coagulation (Rivaroxiban)
- endovascular thrombolysis= thrombolytic injected directly into clot meaning increased dose can be given
Surgical:
-Embolectomy= cutting vessel to remove emboli when only small segment occluded
- Bypass= when longer segment affected due to blood distal to emboli coagulating
- amputation proximal to clot
Why does reperfusion injury occur in acute limb ischaemia and what are the consequences?
What can be done to decrease the risk of reperfusion injury occuring?
Tissue death/breakdown leads to accumulation and release of NO and inflammatory mediators
Cardiovascular collapse
-inflammatory mediators cause wide spread vasodilation inducing distributive shock and secondary injury to kidneys and bowel
ARDS
-inflammatory mediators increase vascular permeability leading to fluid leaking from vessels into alveoli= pulmonary oedema
Renal failure
-myoglobin release from tissue induces myoglobinanemia leading to accumulation of proteins in glomerular basement membrane
What does compartment syndrome occur in acute limb ischaemia?
What are the consequences?
How is it managed?
Increased tissue permeability leads to increase fluid accumulation in compartment, raising the intra-compartmental pressure
- Loss of venous outflow
- Loss of arterial inflow
- Tissue death due to loss of blood supply
Faciotomy
Why does chronic limb ischaemia occur?
What adaptive process occurs in chronic limb ischaemia?
Narrow arteries due to plaques and stiffening
Leads to reduced flow which causes reduced oxygen delivery
Adaption:
- blood travels in arteries at higher pressure to try and deliver adequate oxygen against increased resistance
- collateralisation= new blood vessels form to maintain a blood flow
What signs and symptoms would you expect to see in chronic limb ischaemia?
Intermittent claudication
Resting pain
Absent pulses = collateralisation means blood not flowing through arteries
Arterial ulcers = decrease blood supply compromises healing
Skin changes = hairless due insufficient oxygen to enable growth
What is intermittent claudication?
What is the absolute claudication index?
Crampy, achy pain in calf, thigh, buttock which comes on with exertion (think of as angina of the leg)
ACI= how far patient can walk on flat plane before experiencing pain
