Influence of Wall Compliance on the Flow Patterns in a Patient-Specific Brachio-Cephalic Arterio-Venous Fistula

Abstract

Patients with end stage renal disease require some form of vascular access for treatment, with Arterio-Venous Fistulas (avf) being the preferred form available due to better patency rates. However, they continue to present complications after creation, leading to early or late failure. While many studies are examining the flow in patient-specific fistulas, they often neglect the influence of vessel compliance on its hemodynamics. The objective of this study is to investigate the effect of wall compliance on the complex hemodynamics of a patient-specific brachio-cephalic avf and how it differs from a rigid fistula. Particle Image Velocimetry (piv) was used to capture the flow pattern within the fistula for both steady (Re = 1817) and pulsatile (Reav=1817, Remax=2232) flow conditions. The results were compared to rigid model measurements performed under the same Reynolds number. The streamline plots and coefficient of variation results did not differ significantly between the models; however, the non-dimensional velocity and directional variability results did vary between the two fistulas. A difference of approximately 8% was seen between the two models for both steady and pulsatile flow. The findings of this study suggest that to determine the bulk flow, a rigid model is adequate, but to capture the finer details of the flow, a compliant model is necessary.

Pressure Analysis in Rigid and Flexible Real Arteriovenous Fistula with Thickness Variation In Vitro

“…An arteriovenous fistula (AVF) is considered by most authors as the better vascular access for hemodialysis treatment [ 1 , 2 , 3 , 4 ]. However, this type of vascular access can be affected by problems related to the construction process and its prolonged use, which we can highlight: pseudoaneurysms, intimal hyperplasia, hand edema, among others [ 5 , 6 , 7 , 8 , 9 ].…”

“…Several studies have aimed to analyze the AVF with a rigid wall, disregarding the influence of wall deformation on the flow of these accesses [ 9 ]. Variations in velocity, pressure and shear stress on vascular walls are parameters that directly influence the external remodeling of the vein (increase in vascular diameter).…”

“…Several studies have sought to investigate the phenomena and parameters that influence the result of AVF maturation, highlighting pressure, flow rate and shear stress. Several studies have aimed to analyze the AVF with a rigid wall, disregarding the influence of wall deformation on the flow of these accesses [9]. Variations in velocity, pressure and shear stress on vascular walls are parameters that directly influence the external remodeling of the vein (increase in vascular diameter).…”