NUMERICAL SIMULATION OF THE EFFECT OF VENOUS NEEDLE'S FLOW ON FLOW PARAMETERS OF HEMODIALYSIS GRAFT AND ITS HEMODYNAMIC CONSEQUENCES

Abstract

Arterio-Venous (AV) grafts which are used for hemodialysis, frequently develop intimal hyperplasia (IH) in venous anastomosis and ultimately leads to graft failure which is the major cause of morbidity and mortality in patients with the end stage renal disease (ESRD). Although the high AV access blood flow has been implicated in the pathogenesis of graft stenosis, the potential role of needle turbulence during hemodialysis is relatively unexplored. In the current study, a numerical survey is carried out to investigate the effect of venous needle's flow on hemodynamic parameters of the flow inside a hemodialysis graft. Two cases include the individual graft flow and the graft flow combined with a needle flow which both of them are evaluated and their results are compared to the cell morphology are represented in this research. Blood is considered as an incompressible Newtonian fluid with density of 1050 [Kg/(m3)] and dynamic viscosity of 0.0035 [Pa.s] and the graft was considered as a rigid vessel due to its low compliance. Flow rates were considered 500 and 100 [mL/min] as inlet conditions of the graft and the needle, respectively. Results show that the presence of the needle's flow causes to increase the amount of shear stress and nonuniformity of the shear stress distribution on the graft wall, where the cell alignment is lost in the presence of needle flow. These findings suggest the presence of potential relationship between venous needle flow during hemodialysis and endothelial dysfunction which may lead to vascular injury and graft failure.