The preferred vascular access
The surgically created arteriovenous (AV) fistula is the standard of care and preferred access for hemodialysis.
The AV fistula is constructed by suturing together an artery and a vein so that the arterial pressure in the anastomosis dilates the vein, enabling accommodation of two needles needed for hemodialysis. A newly created fistula must mature (i.e., undergo dilation and remodeling) in order to be functional for dialysis, a process that takes 6-8 weeks.
AV fistulas often fail to mature
Studies over several decades have consistently demonstrated that native mature fistulas have superior longevity, spanning 4 to 5 years, and require minimal secondary interventions compared with other access types. However, despite the clear benefits of mature fistulas, early failure occurs in over 40% of fistulas.
Failure is often due to clotting and thrombosis of the fistula which is caused by turbulent flow patterns around the anastomosis region. Later failures are associated with exposure of the vein to high pressure and wall tension. These pressures cause a thickening of the intimal layer, called intimal hyperplasia, subsequently leading to a narrowing (stenosis) of the vessel lumen. Dember et al, 20081 report a failure rate of 53.4% at 120-150 days after fistula placement.
Local flow patterns and the exposure of the vein to high arterial pressures and flow trigger the onset of remodeling and intimal hyperplasia (wall thickening).
The Need for Innovation
The technique for AV fistula placement has not changed significantly since its introduction in 1966. Given the high failure rates and the lack of a better vascular access, there is a strong need for a new solution that addresses the root causes of access failure.