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Pathology

1. Abnormal communication between arterial and venous circulation
2. 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

1. 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
2. Palpate
   • Thrill palpable
3. Percuss
4. Auscultate
   • "Machinery" continous murmur

Completion

1. Examine rest of patient
2. Determine why fistula formed in the first place

Formation of Cimino-Bresica arteriovenous fistula

1. LA
2. 3-4cm incision over distal 1/3 of forearm midway between radial artery and cephalic vein
3. Cephalic vein mobilised, tributaries ligated
4. Radial artery identified and dissected
5. Ligate distal ends
6. Anastamose ends

Operative complications

1. Thrombosis
2. Venous hypertension
3. High-output cardiac failure secondary to massive run-off through fistula
4. Pseudoaneurysm formation

Clinical determination of degree of shunt caused by fistula

1. 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