Acute + Chronic Limb Ischaemia

Question 1

What is chronic limb ischaemia?

Answer 1

• Peripheral arterial disease, typically of lower limbs causing reduced blood supply
• 5% of males >50yrs have intermittent claudication

Question 2

What are risk factors for chronic limb ischaemia?

Answer 2

• Smoking
• Diabetes mellitus
• Age
• Hyperlipidaemia
• Family history
• Hypertension
• Obesity
• Physical inactivity

Question 3

What are the causes of chronic limb ischaemia?

Answer 3

• Atherosclerosis
• Vasculitis (rarely)

Question 4

What are the clinical features as per the Fontaine classification, for chronic limb ischaemia?

Answer 4

• Stage I → asymptomatic
• Stage II → intermittent claudication
• Stage III → ischaemic rest pain
• Stage IV → ulceration +/- gangrene

The commonest presentation is with pain in the lower limb on exercise (claudication)

Question 5

What is intermittent claudication?

Answer 5

• cramping/aching pain in buttock or calf
• after walking a fixed distance (claudication distance)
• relieved quickly by rest

Question 6

What is critical limb ischaemia?

Answer 6

• Unremitting pain at rest (esp at night)
• May be improved by hanging feet out of bed

Question 7

What is Leriche’s syndrome/triad?

Answer 7

• Aorto-iliac obstruction
  
  • → Buttock + thigh pain
  • → Male impotence
  • → Absent femoral pulses

Question 8

What are signs of chronic limb ischaemia?

Answer 8

• Pulseless
• Pale
• Cool
• Paraesthesia
• Poor wound healing
• Nail dystrophy
• Loss of hair
• Pallor
• Skin changes

Question 9

What is the ABPI classification in limb ischaemia?

Answer 9

• 1 = normal
• 0.6-0.9 = claudication
• 0.3-0.6 = rest pain
• <0.3 = impending gangrene

Question 10

Apart from ABPI, what investigations are done for chronic limb ischaemia?

Answer 10

• FBC → anaemia may exacerbate
• ESR → raised in arteritis
• Blood glucose → DM
• Lipids
• ECG → 60% have evidence of coronary artery disease
• Imaging for site, length + degree of stenosis
  
  • Duplex ultrasound (Gold standard)
  • Also, CT or MR angiography

Question 11

How do you interpret doppler USS waveforms for the degree of stenosis?

Answer 11

• Triphasic → normal
• Biphasic → mild stenosis
• Monophasic → severe stenosis

Question 12

What is the conservative management for chronic limb ischaemia?

Answer 12

• Stop smoking
• Regular exercise
• Weight loss
• Foot care

Question 13

What is the medical management of chronic limb ischaemia?

Answer 13

• Lipid lowering drugs
• Hypertension control
• Diabetes control
• Antiplatelets (clopidogrel / aspirin)
• Peripheral vasodilator → nafridrofuryl oxalate
• Analgesia

Question 14

What are the two surgical options for chronic limb ischaemia?

Answer 14

1. Endovascular - angioplasty +/- stent:
   
   • Cross the narrowing or blockage w/ wire, pass balloon over wire, stretch open artery + place stent if needed; less invasive/less risk - better for high risk pts; good for short lesions
2. Open surgical reconstruction:
   
   • Use a conduit (vein or plastic pipe) to go around blockage + restore blood flow distally
   • May be anatomical - fem-pop, fem-distal, aorto-bifemoral
   • Or extra-anatomical - axillo-femoral, fem-fem crossover
   • Ultimately @ 1yr following attempted lower limb bypass operation, 12% of those who initially had critical limb ischaemia + 1% of those with intermittent claudication end up having a major amputation

Question 15

What is acute limb ischaemia?

Answer 15

• Sudden onset (<2 weeks)
• Painful lack of blood flow to a limb

Question 16

What are the presenting features of acute limb ischaemia (6Ps)?

Answer 16

• Pain
• Pallor
• Paralysis
• Paraesthesia
• Perishingly cold
• Pulseless

Question 17

What are causes of acute limb ischaemia?

Answer 17

• Thrombosis in situ - plaque rupture in vessel w/ stenosis (same pathology as MI)
• Embolism → arrhythmia, fat embolism, heart valve replacement, surgery/angio
• Dissection (usually aortic)
• Trauma
• Stent/graft occlusion
• Compartment syndrome

Question 18

How is a thrombus different to embolus in presentation for acute limb ischaemia?

Answer 18

• Thrombus has slower onset (hours to days, not immediate)
• History of intermittent claudication
• Less severe
• Absent contra-lateral foot pulses

Question 19

What investigations are done for acute limb ischaemia?

Answer 19

• Bloods → FBC, U+Es, G+S, INR (pre-op bloods)
• ECG → ?cause of embolus, pre-op assessment
• Imaging → Duplex USS

Question 20

What is the management of acute limb ischaemia?

Answer 20

• This is an emergency!
• ABCDE
• NBM + IV fluids
• Unfractionated heparin to prevent extension
• Antibiotics if infection
• Further management depends on extent of occlusion:
  
  • if complete → urgent surgery → embolectomy/bypass
  • if not complete → angiogram + observation