Thrombosis and stenosis are major complications for dialysis patients. Previous research posits that areas of low Wall Shear Stress (WSS) influence dialysis complication risk in patients. Fluidic devices that replicate vein geometries of the cephalic arch of those with brachiocephalic arteriovenous fistulas (AVF) allow for characterization of WSS and flow behavior in a patient specific way. This study reviews design changes made to the fluidic devices in order to recreate pathologic flow rates on chip (from 20 mL/min to 300 mL/min), along with time series imaging of pathologic flow and resultant WSS. These changes revealed flow transitions from laminar to turbulent as flow rates increased. Interestingly, this transition from laminar to turbulent flow occurs at different flow-rates in different regions of the device, and is strongly influenced by overall device geometry as well as local topography of the wall surface. WSS profiles were generated for five fluidic models at a flow rate of 300 mL/min to model. This includes an idealized 9 mm diameter cephalic arch model in AVF patients, and four total patient specific models: two patients, each with a model at 3 and 12 months after AVF creation. These profiles recapitulate WSS values expected under pathologic flow while capturing systematic changes in WSS over time due to vein remodeling, in a patient-specific manner. These results will help understand overall changes in hemodynamics and WSS in patients under dialysis treatment and why certain patients are prone to AVF complications.
Maren Klineberg (Thu,) studied this question.