Arteriovenous graft (AVG)
A type of vascular access made with prosthetic interposition between an artery and a vein. The main aim is to:
- link two vessels which are located apart from each other
- create a high capacity prosthetic segment between an artery and a vein which can also be used for the insertion of HD catheters.
AVG is the second method of choice for vascular access in haemodialysis after arteriovenous fistula (AVF). It is however indicated as the first line of treatment in:
- cases of paucity of autologous material and/or for a short predictable period of hemodialytic treatment (children)
- patients with short obese limbs
- patients with extreme vascular fragility e.g.- thrombocytopenic purpura
Prosthetic arteriovenous grafts can be:
- biological
- e.g. - Denatured homologous vein allograft, Cryopreserved saphenous vein Sheep collagen grafts
- they are of limited availability and expensive
- can be used safely in patients with a history of multiple failed synthetic grafts
- synthetic
- e.g. - Dacron, polytetrafluoroethylene (PTFE)
Upper limb is the preferred insertion site however the thigh can be used if the upper-limb sites are exhausted.
Lifespan of AVG is much shorter when compared to AVF. Complications of AVG include:
- thrombosis
- caused by stenosis, hypotension, and excessive compression for hemostasis
- dypiridamole, sulfinpyrazone, ticlopidina, and combined aspirin and dipyridamole can be used to reduce the risk of graft thrombosis
- infections
- incidence of HD-related bacteremia in AVG is ten times more than in AVFs (2.5 episodes per 1,000 dialysis procedures versus 0.2)
- patients should be advised on the importance of hygiene since it seems to be the most important modifiable risk factor
- management include intravenous antibiotics and total or subtotal or partial graft excision
- pseudo aneurysm
- refer for resection if they are >2 times wider than the graft or rapidly increasing in size or when the overlying skin appears under duress.
- ischemia
- more common in AVGs than AVFs
- vascular steal syndrome and ischemic monomelic neuropathy should be differentiated
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