Acute Limb Ischaemia

Question 1

Acute Limb Ischaemia General

Answer 1

• Most often due to either thrombotic occlusion of previously occluded or thrombosed, or embolus from different site
• Without surgical revascularisation, necrosis within 6 hours
• Effect of arterial occlusion depends on state of collateral supply
• Collateral supply in leg is usually inadequate unless there has been pre-existing occlusive disease
• Subclavian artery has many collateral vessels
• Critical limb ischaemia different to acute, critical is chronic at-rest iscaemic pain, ulcers or gangrene in both legs attributable to occlusive arterial disease

Question 2

Acute Limb Ischaemia Aetiology

Answer 2

• Embolism (AF, mural, valves, aneurysm, tumour, foreign body)
• Thrombosis: most cases result from thrombus at sight of atherosclerotic narrowing can be acute due to rupture or chronic due to gradual extension of thrombus with development of collateral vessels
• Trauma
• Reynaud’s
• Compartment syndrome (ortho, vascular (phlegmasia cerulea dolens), soft tissue injury)
• Arm ischaemia is most often cardiac

Question 3

Acute Limb Ischaemia Presentation

Answer 3

• H/E can identify embolic vs thrombotic
• Differentiated by rapidity of onset of symptoms, features of pre-existing disease, potential source of embolus, state of pulses (contralateral leg will be absent if thrombotic, present if embolic), palpation of artery (will be calcified in thrombotic)
• Affected limb becomes pale, pulseless, painful, paralysed, paraesthetic and perishing with cold
• Onset of fixed mottling implies irreversible change

Question 4

Acute Limb Ischaemia Ix

Answer 4

• Doppler then CT-angiogram if salvagable
• Bloods
• If diagnosis in doubt, perform urgent arteriography
• Ix to find source of embolus
  
  • ECG, echo, aortic USS, popliteal and femoral USS

Question 5

Acute Limb Ischaemia Management

Answer 5

• Heparin, surgery; aspirin, statins
• Urgent admission, often requires surgery
• Heparinisation required immediately
• Ischaemia following trauma may require reconstruction
• Check for compartment syndrome
• If occlusion is embolic then surgical embolectomy (Fogarty balloon embolectomy catheter) or local intra-arterial thrombolysis, anticoagulation needed to prevent recurrence
• If due to thrombotic disease, intra-arterial thrombolysis, angioplasty or bypass surgery, anticoagulation needed to prevent recurrence
• Intra-arterial thrombolysis is a slow process, so only used in non-life threatening limb ischaemia
• Low dose aspirin for most cases
• Statins

Question 6

Acute Limb Ischaemia Complications

Answer 6

-Reperfusion injury may cause more damage than initial ischaemia

Question 7

Acute Limb Ischaemia Prognosis

Answer 7

• Complete ischaemia will lead to extensive necrosis within six hours unless limb revascularised
• Mortality associated with acute limb ischaemia is high