vascular

Question 1

Describe vascular anatomy of the lower limb

Answer 1

Abdominal aorta begins at T12 and bifurcates at L4 into the left and right common iliac arteries
Common iliac bifurcate into the internal and external iliacs.
External iliac becomes the common femoral artery, which bifurcates into the superficial femoral artery, and the deep femoral artery (profunda femoris)
Superficial femoral artery becomes the popliteal artery, which divides into the anterior tibial artery and the tibioperoneal trunk
Anterior tibial artery becomes the dorsalis pedis
Tibioperoneal trunk divides into the posterior tibial artery and the peroneal artery

Question 2

What is acute limb ischaemia?

Answer 2

A sudden reduction in the perfusion to a limb causing potential threat to limb viability

Question 3

What are the causes of acute limb ischaemia?

Answer 3

Embolus
Thrombus
Trauma
Dissection
Illicit drug use
External compression

Question 4

What are the causes of embolus causing acute limb ischaemia?

Answer 4

Atrial fibrillation (80%)
Mural thrombus following acute MI (thrombi that attach to the wall of a blood vessel and cardiac chamber)
Valvular genetation
Proximal aneurysms or plaque

Question 5

Describe CHA2DS2Vasc score

Answer 5

Congestive cardiac failure
Hypertension
Age >65 (+1), >75 (+2)
Diabetes
Stroke or prev thromboembolism (+2)
Vascular (PAD)

Question 6

What are the thrombotic causes of acute limb ischaemia?

Answer 6

Atherosclerosis
Popliteal aneurysm
Graft/stent/stent-graft occlusion

Question 7

What are the classifications of graft/stent/stent-graft occlusions?

Answer 7

Within 1 month - technical
Within 1 year - neointimal hyperplasia
>1 year - progression of atherosclerotic disease

Question 8

What is the clinical classification of acute limb ischaemia?

Answer 8

I - viable (limb not immediately threatening, cap refill normal, no paralysis and normal sensation)
IIa - marginally threatened (salvageable if treated promptly, slow cap refill, partial loss of sensation, negative arterial Doppler signal)
IIb - immediately threatened (salvageable if immediately treated, as above but partial paralysis, may have complete loss of sensation)
III - unsalvageable (absent cap refill, fixed staining, complete paralysis, complete sensation loss, negative Doppler signal)

Question 9

Presentation of acute limb ischaemia?

Answer 9

Pain
Pallor
Paraesthesia
Paralysis
Perishingly cold
Pulselessness
Calf tenderness (concerning, implies severe muscle ischaemia)

Question 10

What is the pathophysiology of limb colour changes in acute limb ischaemia?

Answer 10

1. White - vasospasm and no venous filling
2. Mottling - vasodilation due to smooth muscle hypoxia and capillaries fill with stagnant cyanotic blood (mottling) which blanches on pressure
3. Fixed - if repercussion is not achieved arteries thrombus and capillaries rupture causing fixed blue mottling that does not blanch on pressure
   In acute-on-chronic these changes might not be seen due to collaterals