Haemodialysis access maintenance

What is haemodialysis access maintenance?

Haemodialysis is a treatment in which a machine is used to filter out fluids and waste from the blood to restore a proper electrolyte balance in patients with kidney failure. There are three main access routes for this: intravenous catheters (thin plastic tubes which are placed in a blood vessel at the level of the shoulder or less often in the groin); arteriovenous (AV) fistulas, and synthetic grafts.

The most common vascular access method used is the AV fistula. This is a channel created by directly connecting an artery and a vein. A synthetic AV graft is small artificial tube placed under the skin connecting an artery to a vein, and tends to be used when the patient is unsuitable for an AV fistula.

Both AV fistulas and synthetic grafts may become narrowed, thrombosed (obstructed by blood clots) or blocked. In order to keep them clear, you may undergo a percutaneous (through your skin) treatment, such as percutaneous thrombolysis, thrombectomy, balloon angioplasty and stenting. The process of keeping the AV fistula or graft clear is called haemodialysis access maintenance.

How do the procedures work?

Haemodialysis access maintenance procedures are performed on an out-patient basis and use X-ray guidance. Your vital signs will be monitored during the procedure.

After numbing your skin, the interventional radiologist will insert thin wires and small tubes (catheters) through a tiny hole in your skin into your arm’s blood vessels and the AV fistula or synthetic graft. If there is a blood clot present, the interventional radiologist can remove it by performing a procedure called “thrombectomy” or try dissolving the thrombus with pharmacologic agents (thrombolysis).

If you undergo combined therapy with a thrombectomy or thrombolysis, you will be kept under observation for 24-48 hours with repeated follow-ups using angiography.

In order to accurately diagnose the location and severity of any narrowing in the AV fistula, the interventional radiologist will inject a contrast dye into the fistula and will perform a fistulogram on the area. The interventional radiologist will then insert a tiny inflatable balloon into the narrowed area using a guidewire. As the balloon expands, it gently widens the vessel wall and restores the flow through the AV fistula or graft. In some cases, the interventional radiologist will place a stent (a specially designed metal tube) in the vessel to support the vessel walls and keep them open.

Why perform it?

If there is a blockage or narrowing in an AV fistula or synthetic graft, it will not be possible to undergo an efficient haemodialisys. The development of percutaneous maintenance techniques has prolonged the life of AV fistulas and grafts. As a result, haemodialysis access maintenance procedures reduce the need for temporary central catheters that are at higher risk of infection.

What are the risks?

Some complications occur in up to 10% of patients whose AV fistulas or synthetic grafts are blocked by blood clots. However, major complications are less common in patients in whom access is not threatened by blood clots. Risks include blood clots in arteries, bruising, bleeding and perforating or rupturing the wall of the vessel.

As with other percutaneous procedures, there is a small risk of infection and damage to a blood vessel.

Bibliography

1. Aruny JE, Lewis CA, Cardella JF, Cole PE, Davis A, Drooz AT, Grassi CJ, Gray RJ, Husted JW, Jones MT, McCowan TC, Meranze SG, Van Moore A, Neithamer CD, Oglevie SB, Omary RA, Patel NH, Rholl KS, Roberts AC, Sacks D, Sanchez O, Silverstein MI, Singh H, Swan TL, Towbin RB, Trerotola SO, Bakal CW; Society of Interventional Radiology Standards of Practice Committee. Quality Improvement Guidelines for Percutaneous Management of the Thrombosed or Dysfunctional Dialysis Access.  J Vasc Interv Radiol. 2003 Sep; 14(9 Pt 2):S247-53.