Acute arterial occlusive disease

Question 1

What are the common causes of acute arterial occlusion?

Answer 1

• Embolus (40%)
• Thrombus (40%)
• Trauma (including during angioplasty)

Predisposing factors include dehydration, hypotension, unusual posture, malignancy, hyperviscosity, AF and thrombophilia

Question 2

How can you differentiate between embolic and thrombotic occulsion?

Answer 2

Onset:

• Embolus:
  
  • sudden onset
  • very severe symptoms due to lack of collaterals
• Thrombosis:
  
  • Inidious onset
  • Less severe symptoms as advanced collaterals

Source:

• Embolus
  
  • Normally identifiable e.g. AF/AAA/post MI/endocarditis (heart valve)
• Thrombosis
  
  • No obvious source

Pulses:

• Embolus
  
  • Previously normal
  • normal contralateral pulses
• Thrombosis
  
  • Long-standing decreased pulse bilaterally

History:

• Embolus
  
  • No history of arterial disease
• Thrombosis
  
  • Previous history of intermittent claudication, stroke, MI ect.)

Question 3

What is thombosis prediposed by?

What is embolic occulsion prediposed from?

Answer 3

• Thrombosis is prediposed to by Virchow’s triad:
  
  • Endothelial dysfunction: trauma, inflammation or atheroma
  • Changes in blood flow: statis or slow flow
  • Changes in blood coagulability: inflammatory response/congential causes
• Embolic occulsion is occulsion of a vessel by a mass of material transported in the bloodstream, most commonly fragments of thrombus (thromboemboli).
• Thromboemboli may arise from the left atrium in AF, the left ventricle post MI, heart valve in endocarditis or mural thrombi from an AAA

Question 4

List the clinical symptoms of acute arterial occulsion

Answer 4

The six P’s:

• Pulseless
• Painful
• Pallor
• Perishingly cold
• Paralysis*
• Paraesthesia* (abnormal sensation such as tingling, tickling, pricking, numbness or burning)

*Paralysis and paraesthesia indicate a threatened limb, as well as pain on passive movement or squeezing the calf

Question 5

How can you differentiate the symptoms and signs of acute arterial from acute venous occlusion?

Answer 5

• Acute arterial occlusion will cause the 6 P’s
  
  • Pulseless
  • Painful
  • Pallor
  • Perishingly cold
  • Paralysis
  • Paraesthesia
• Venous occlusion will cause:
  
  • swelling
  • redness
  • warmth
  • pain.
  • Engorgement of superficial vessels, ankle oedema and Homan’s sign (pain on dorsiflexion of foot) may be present

Question 6

Describe the natural history of untreated acute arterial occulsion

Answer 6

Untreated, the patient will lose the limb, and the degeneration process will cause life-threatening illness

Question 7

Describe the natural history of treated arterial occulsion

Answer 7

• Treatment hopes to save the limb, but it is mandatory to observe the risk of reperfusion injury.
• Reperfusion injury may cause more damage than the ischaemia itself.
• The increased blood supply brings nutrients and immune mediators that increase inflammation.
• Cell leakage leads to acidosis and hyperkalaemia.
• Compartment syndrome may occur in tight fascial planes.
• Acute limb ischaemia may lead to peripheral nerve damage and chronic pain syndromes.