A numerical study of hemodynamic effects on arteriovenous fistula calcification

Arteriovenous fistula (AVF) calcification is a common complication in hemodialysis patients that leads to AVF dysfunction and decreases the AVF survival, but the mechanisms of AVF calcification, especially the role of hemodynamic changes in AVF calcification have not been fully investigated. In this study, a computational fluid dynamics (CFD) model was carried out based on AVF, at the distal anastomosis of the cephalic vein and radial artery, generated from a patient-specific computed tomography (CT) angiography and Doppler ultrasound image. Hemodynamic factors were considered to explore the mechanisms responsible for the initiation and progression of AVF calcification. Five stages in one cardiac cycle were chosen to be studied for the velocity field, pressure, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI). Blood pressure was higher in the arteriovenous anastomosis, and variations of great amplitude of pressure were examined during the cardiac cycle. Blood pressure, transient shear stress, TAWSS, and OSI were higher in the arteriovenous anastomosis and at the bottom of expanded outflow vein, and these sites were highly consistent with the calcified areas shown on CT angiography. On the contrary, no calcification was found in sites where streamline was stable, blood pressure did not change dramatically, as well as TAWSS and OSI were lower. It was shown that AVF calcification was correlated with hemodynamic changes, which may contribute to further understanding the mechanisms of AVF calcification and providing scientific evidence to inform the optimization of surgical strategies and the development of personalized interventional measures in clinical contexts.