[Orthotopic arteriovenous fistula in dialysis patients: a special application of fluid dynamic processes]

Our experiments describe the flow patterns in translucent models of AV fistulas. The elasticity of the models is similar to human vessels walls. Dying of particular flow threads with methylene blue visualizes the flow and its disturbances in 4 classical models. The flow dynamics were 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 pattern in side to side fistulas and in end to side fistulas with a narrow angle show regions of separation. This may lead to microthrombus formation and early failure. High shear stress causes endothelial lesions and thus induces stenosing intimal reactions. A favourable flow pattern was seen in end to side fistulas with a broad angle, as well as in end to end fistulas.