The effect of assumed boundary conditions on the accuracy of patient-specific CFD arteriovenous fistula model.

Computational fluid dynamics (CFD) modelling has been a useful non-invasive measurement tool to analyse the effects of blood flow in diseased arteriovenous fistula (AVF). To translate CFD findings for clinical use, it is essential to model the AVF as closely as possible to the physiological conditions. The AVF geometry consists of three boundary nodes, which require appropriate flow conditions prescribed to each of them. To this end, we modelled three AVF geometries, with three different, commonly used boundary conditions: velocity based on patient-specific waveforms, assumed flow split condition for the retrograde flow and assumed flow split condition for the antegrade flow. Three patient-specific geometries were acquired from an in-house ultrasound scanning system. The patient-specific waveforms were also obtained during these scanning sessions for the CFD models. WSS distribution and recirculating flows were observed at different locations for the three patient datasets, with different sets of boundary conditions. These effects were prominent at the anastomosis and dependent on the geometry of the AVF. There were also discrepancies between resistance values estimated from the patient-specific CFD models and the Hagen–Poiseuille model. These findings highlight the importance of modelling patient-specific AVFs with appropriate boundary conditions for better identification of diseased AVF. [ABSTRACT FROM AUTHOR]