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When Fistula cannot be used: Causes of AV Graft Failure

By Laminate Medical
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When kidney function is compromised and hemodialysis is deemed to be necessary, vascular access must be made in order to allow the repeated needle insertions.  The preferred and safest method of gaining dialysis access is via an AV fistula, directly connecting the vein and the artery. Approximately one fifth of end stage renal disease patients require an alternative access method, usually due to small or weak veins, a lack of fistula maturation or underlying disease that prevents creating a functioning fistula.

In cases where an AV fistula cannot be used, the preferential method of vascular access is the arteriovenous graft. The AV graft is a surgically created artificial conduit, tunneling under the skin and connecting an artery to a vein in order to allow for easy cannulation during hemodialysis.

While the procedure is relatively simple and in most cases cannulation can be done as soon as 2-3 weeks after procedure, AV grafts are prone to infection and clotting and have a short lifespan. Studies show that more than half of the grafts placed will fail after approximately 6 months, the number rising to 95% fail after 2 years, requiring salvage procedures, new grafts and costly treatments.  Arteriovenous graft failure is the leading cause of hospitalization of end stage renal disease patients.

Main Causes of AV graft failure

The majority of arteriovenous grafts develop stenosis or thrombosis. The main cause of AV graft failure is hyperplasia, a narrowing and blockage at the point of graft vein connection, resulting in graft flow decline and eventually causing graft thrombosis. Graft thrombosis accounts for approximately 80% of graft failures

The next most common cause of arteriovenous graft failure is infection.

Incidence of infection is reported at 11-35%, with infection being ten time more common with AV grafts as opposed to AV fistulas. Infected grafts tend to thrombosis (blood clots that form inside the blood vessel and obstruct the blood flow), peri-graft hematomas (blood collecting outside of the blood vessels, near the graft, and causing pain and a risk of clotting) and pseudo-aneurysms (hematomas resulting from a leaking hole in a blood vessel, often resulting in a painful, infected mass). The incidence of graft infection increases with time. Hospitalization due to sepsis is associated with heart failure and strokes.

As stated before, the risk of thrombosis and infection of AV grafts is 10 times higher than with AV fistulas and rapidly rises when secondary health issues such as obesity, diabetes, etc. are involved.

When considering your vascular access options, it is important to take all risk factors into consideration. AV fistulas are by far the safest and longest lasting form of vascular access. Read about Laminate Medical Technology’s VasQ, external support that allows for improving maturation and patency rates of AV fistula.

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