Arteriovenous fistula
Pathology
- Abnormal communication between arterial and venous circulation
- Types
- Congenital
- Multiple
- Traumatic
- Iatrogenic
- Surgical:
- synthetic PTFE (poly-tetra-fluoro-ethylene) graft#
- vein
Types of upper-limb surgical AV fistula
- Radio-cephalic
- Cimino
- Ulna-basic (nb, ulnar artery is the dominant artery)
- Brachio-cephalic (problems with distal steal phenomenon; can be overcome with a proximal jump graft)
- Brachio-basilic
AV-fistulae fail due to neo-intimal hyperplasia; causing progressive thickening and occlusion of the intima
Principles in fistula formation
- Start peripheral
- Work proximally
Approach
- Expose area
- Check both sides exposed
- Inspect
- Swelling over distal forearm
- Describe as for any lump / swelling
- AV fistula may be iatrogenic (Cimin-Bresica fistula) or traumatic or congential
- Lump may be pulsatile
- Palpate
- Thrill palpable
- Percuss
- Auscultate
- "Machinery" continous murmur
Completion
- Examine rest of patient
- Determine why fistula formed in the first place
Formation of Cimino-Bresica arteriovenous fistula
- LA
- 3-4cm incision over distal 1/3 of forearm midway between radial artery and cephalic vein
- Cephalic vein mobilised, tributaries ligated
- Radial artery identified and dissected
- Ligate distal ends
- Anastamose ends
Operative complications
- Thrombosis
- Venous hypertension
- High-output cardiac failure secondary to massive run-off through fistula
- Pseudoaneurysm formation
Clinical determination of degree of shunt caused by fistula
- Branham-Nicoladoni sign
-
Carotid pulse palpated and tourniquet placed around proximal affected limb and inflated above systolic pressure
-
Pulse during period when tourniquet inflated compared with pulse beforehand
- Normally AV fistula causes hyperdynamic circulation - sinus tachycardia
- When fistula cut off, circulation should correct itself
- Indicator of left to right shunt
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