2 options for HD

• AVF: anastomosis b/n artery and vein allowing vein to enlarge and arterialize to become accessible and provide adequate flow for HD; takes 8-12 weeks to mature (~50% never mature)

  • Radiocephalic/forearm (preferred)

    • Low rates of maturation

    • Typical stenosis at juxtaanastomotic segment (w/n 2 cm).

  • Brachiocephalic/upper arm (2nd preferred)

    • Used when radial artery or forearm cephalic vein are unsuitable for RC creation

    • High rate of dialysis associated steal syndrome which precludes subsequent ipsilateral forearm fistula creation

    • Typical stenosis at cephalic arch.

  • Brachiobasilic/upper arm (requires 2 surgeries)

    • Used when upper arm cephalic vein unsuitable for AVF creation.

    • Difficult surgery; high rate of steal syndrome

    • Typical stenosis at proximal swing segment.

• HD graft: artificial graft with prosthetic conduit that connects artery to vein like AVF; takes less time to mature but poorer long-term patency and higher rates of infection.

  • Forearm loop

  • Upper arm

  • Thigh

Vessels must be a minimum diameter to be used:

• Veins: 2.5 mm AVF; 4.0 mm for AVG

  • Measured after dilation via tourniquet or BP cuff.

• Artery for both 2.0 mm

High volume, low resistance, monophasic flow.

Rule of 6s

• Flow >600 mL/min in draining vein measured 10 cm from anastamosis over 3 cardiac cycles.

• Diameter >0.6 cm in draining vein

• No more than 0.6 cm deep

• Should mature by 6 weeks

Occurs in >50% of newly created AVFs; investigate if no maturation by 6 weeks.

Causes:

• Inflow stenosis: MCC; does not allow for dilation and arterialization of fistula.

• Competing outflow veins:

  • Accessory veins: naturally occurring branches arising from venous outflow tract; treat with ligation and embolization.

  • Collateral veins: alternative drainage pathways; develop in setting of downstream stenosis; treat by addressing underlying stenosis.