Abstract
<jats:p>In the United States, roughly 550,000 people receive routine hemodialysis for end-stage renal disease. This treatment requires an arteriovenous access, most commonly a brachiocephalic fistula. However, these accesses often fail due to stenosis in the cephalic arch (CA), a common complication whose underlying causes remain unclear (Bennet et al., 2015). To characterize the hemodynamic environment in the CA, we employed patient-specific millifluidic models that were perfused with blood-mimicking fluid containing fluorescently labelled beads to visualize flow behaviors. We perfused our models across physiologic (28-45 mL/min) and elevated (60-423 mL/min) flow rates and quantified wall shear stress (WSS) and streamline angle as a measure of flow disturbance. Our findings show that the bulk curvature and remodeled wall topography each create regions of persistently low WSS, consistent with prior clinical observations (Hammes et al., 2016). Moreover, remodeled wall topography promotes disturbed flow at elevated flow rates, a hemodynamic profile associated with various vascular pathologies (Chiu & Chien, 2011). Independently performed computational fluid dynamics (CFD) modeling complements these results, showing that remodeled wall topography promotes vortex formation at elevated flow rates, as assessed by Q-criterion. Collectively, our experimental and computational results provide strong evidence for geometry-driven disturbed flow in the CA at elevated flow rates. Notably, we observed disturbed flow at flow rates as low as 81 mL/min, far below the 600 mL/min required for hemodialysis. Disturbed flow thus offers a plausible mechanism that relates access flow rates to the vascular pathologies that precede access failure.</jats:p>