  The transitional flow which initiates within the junction (anastomosis) of an
arteriovenous fistula (AVF) is known to be a contributing factor in the onset
of vascular disease. A novel treatment method involving the implantation of a
flexible stent across the anastomosis has enabled the retention of a large
proportion of functioning AVFs, despite the propensity for stent malapposition
to occur at the sharp inner curve of the anastomosis. Large Eddy Simulations
(LES) of a patient-specific AVF with and without the presence of a stent
captured oscillatory flow behaviour emanating from the interface of the two
inlet flows in the stent-absent case, however, these oscillatory features were
subdued in the stented case. The stent-absent case generally had higher
Turbulent Kinetic Energy (TKE) in the anastomosis which led to larger
cycle-to-cycle variations in wall shear stress (WSS). The significantly lower
TKE generated at the heel of the stented AVF was contained within the
malapposed stent, thereby resulting in lower WSS fluctuations. However, a
slight increase in turbulence downstream of the malapposed stent edge was
noted. This detailed study reveals a significant decrease in turbulence within
the AVF in the presence of the stent, thereby, providing a level of
understanding underpinning the success of the treatment strategy from a fluid
dynamic perspective.
