An arteriovenous fistula (AVF) is a surgically created vascular connection between a vein and an artery in an extremity that serves as an access for hemodialysis. AVF patency ranges between a few weeks and several years. The major cause of AVF failure is stenosis, a local narrowing of the vessel, that is associated with oscillations in wall shear stresses (WSS) which occur at sites where the flow is disturbed. Flow disturbances result from the geometric features of AVF and the pulsatility of arterial blood flow. However, little is known about the effects of variations in different characteristics of arterial pulse wave, such as waveform, amplitude or frequency on flow patterns and disturbance in AVF. Ten cases of pulsatile flow in end-to-side AVF were defined with different amplitudes and frequencies, all within their physiological ranges for AVF. Employing computational fluid dynamics, these cases were simulated, and their wall areas with WSS oscillations were compared. The amount of AVF wall with oscillatory WSS was found correlated linearly with pulse amplitude (R2=0.92), whereas pulse frequency was found to have much weaker correlation with WSS oscillations (R2≈0). Moreover, the distributions of WSS oscillations were roughly equal in all cases. It was concluded that pulse wave amplitude is the dominant factor in the intensity of flow disturbance in end-to-side AVF. Correlations between pulsatility and flow disturbance can be used by clinicians in assessing probability of complications, which may help in AVF surveillance and care.
