Clinical Assessment
Claudication
- Calf or thigh pain precipitated by exercise
- Usually occurs after predictable distance
- Described as 'cramp' or 'tightness'
- Relieved by rest
- Progression of symptoms is important - worsening or improvement
- Impact on social function should be identified
- Need to differentiate form spinal stenosis
- Also cause exercise induced leg pain
- Usually associated with neurological symptoms and relieved by spinal flexion
- Peripheral pulses can be present in patients with intermittent claudication
Critical limb ischaemia
- Characterised by rest pain
- Occurs when foot is elevated (e.g. in bed)
- Improved with foot dependent
- May be associated with ulceration or gangrene
- Foot pulses are invariably absent
Non-invasive testing of arterial patency
Arterial investigations are used to:
- Confirm the clinical impression of arterial disease
- Assess disease severity
- Preoperative planning of surgical or radiological interventions
Hand-held doppler
- Reflection of an ultrasound wave off a stationary object does not change its frequency
- Reflection off a moving object results in a change of frequency
- The change in frequency is proportional to velocity or blood flow
- Hand held 8 MHz doppler probe is used to assess arterial system
- Can be used to measure arterial pressures
- Measurements can be made at rest and after exercise
- In normal individual lower limb pressures are greater than upper limb
- Ankle-brachial pressure index (ratio of best foot systolic to brachial systolic pressure)
- In normal individuals pressures do not fall flowing exercise
- In claudicants the ABPI falls and recovery is delayed
- In diabetic lower limb pressures are falsely elevated due to calcification in the vessel wall
Toe pressures
- Provides accurate assessment of distal circulation
- Not influenced by calcification in pedal vessels
- Medical calcification particularly seen in diabetics
- Normal toe pressures are 90-100 mmHg
- Toe pressure less than 30 mmHg suggests critical limb ischaemia
Duplex ultrasound
- Combined pulsed doppler and real time B mode ultrasound
- Allows imaging of vessels and any stenotic lesion
- Flow and pressure wave form can be also be assessed
Doppler wave forms from normal and diseases arteries
In normal individuals a 'triphasic' wave is obtained
- Rapid antegrade flow during systole
- Transient reverse flow in early diastole
- Slow antegrade flow in late diastole
An arterial stenosis results in the following distal to the lesion:
- Decreased rate of rise of the antegrade flow
- A reduced amplitude of the forward velocity
- Loss of reverse flow (i.e. a 'biphasic' wave form)
- At the stenosis velocity is increased
- Severe stenosis result in a monophasic waveform
- Duplex ultrasound has sensitivity of 80% and specificity of 90% for stenotic lesions in the femoral and
popliteal segments
Pulse generated run off
- Proximal occlusion often causes poor filling of crural vessels on arteriography
- Rapid cycling of a proximal cuff generates arterial pulse wave
- P GR allows functional testing of distal arterial patency
Magnetic resonance angiography
- Time of flight sequences
- No contrast required.
Invasive vascular assessment
Angiography
- Usually performed using digital subtraction techniques
- Catheter inserted using Seldinger technique
- Femoral artery is commonest site of venous access
- Generally safe procedure performed under local anaesthetic
- Potential complications include
- Contrast-related
- Anaphylactic reaction
- Toxic reactions
- Deterioration in renal function
- Technique-related
- Haematoma
- Arterial spasm
- Sub-intimal dissection
- False aneurysm
- Arteriovenous fistula
- Embolisation
- Infection
CT angiography
- Required intravenous contrast and ionising radiation
- Spiral CT and reconstruction can provide detailed images
- Particularly useful for the assessment of aneurysmal disease
Bibliography
Donnelly R, Hinwood D, London N J M. Non-invasive methods of arterial and venous
assessment. Br Med J 2000; 320: 698-701.
Ubbink D T, Tulevski I I, Hartog D et al. The value of non-invasive techniques for
the assessment of critical limb ischaemia. Eur J Vasc Endovasc Surg 1997; 13: 396-300.
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