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Arteriovenous fistula

An arteriovenous fistula is a surgically created anastomosis between an artery and a vein. Its main use is to dilate a vein for easier access in patients requiring regular haemodialysis.

Examining an AV fistula

Look

  • General inspection
    • Patient well/unwell
    • In pain
  • Fistula
    • Type of fistula
      • Radiocephalic AV fistula (most): radial artery to cephalic vein at wrist
      • Brachiocephalic AV fistula = brachial artery to cephalic vein in antecubital fossa
      • Brachiobasilic transposition AV fistula = brachial artery to transposed basilic vein in upper arm
    • Scars
    • Signs of inflammation: rash, erythema, swelling
    • Arm elevation test (for outflow obstruction): fistula should collapse on arm elevation
  • Veins              
    • Presence of collateral veins (suggest venous stenosis)
  • Hands – compare to other side
    • Oedema
    • Signs of ischaemia (Steal syndrome = vascular insufficiency secondary to AV fistula)

Feel

  • Thrill: a thrill is normal but it shouldn’t be pulsatile
  • Consistency: should be soft and easily compressible
  • Augmentation test (for anastomotic stenosis): occlude vein 1-2 cm above anastomosis. If arterial pressure is adequately conducted (i.e. there is no anastomotic stenosis), a pulsation in the vein will be seen. NB: if vein is pulsatile anyway, there is venous outflow stenosis.

Listen

  • Bruit: should be a soft machinery–like rumbling sound (high-pitched = stenosis)

Questions

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