ORTHOTOPIC ARTERIOVENOUS-FISTULAS FOR HEMODIALYSIS - AN EXCEPTIONAL FLUID DYNAMIC PROBLEM

Our experiments describe the flow patterns in translucent models of AV fistulas. The elasticity of the models is similar to human vessels wa lls. Dying of particular flow threads with methylen blue visualizes th e flow and its disturbances in 4 classical models. The flow dynamics w ere investigated with parallel inflow. The volume flow was constant at 200 and 400 ml/min., with a volume flow ratio of 80:20. The flow patt ern in side to side fistulas and in end to side fistulas with a narrow angle show regions of separation. This may lead to microthrombus form ation and early failure. High shear stress causes endothelial lesions and thus induces stenosing intimal reactions. A favourable flow patter n was seen in end to side fistulas with a broad angle, as well as in e nd to end fistulas.