Brachial artery wall shear stress as measured by ultrasound vector flow imaging for evaluating arteriovenous fistula stenosis in patients on hemodialysis.

Background: Wall shear stress (WSS) is a key hemodynamic factor influencing vascular remodeling. Abnormal vascular remodeling may lead to arteriovenous fistula (AVF) stenosis. This study aimed to investigate the relationship between AVF stenosis and brachial artery WSS in patients on hemodialysis using vector flow imaging (V-flow). Methods: Data from patients with 113 end-stage renal disease (ESRD) (66 males and 47 females; mean age 57.7±13.1 years) undergoing hemodialysis via AVF between December 2024 and February 2025 were included. Brachial artery parameters ipsilateral to the AVF constituted the study group, while the contralateral side served as the control group. Based on the Chinese expert consensus on ultrasound interventional therapy for hemodialysis vascular access (2024 edition), the study group was further divided into stenosis (n=43) and non-stenosis (n=70) groups. Maximum wall shear stress (WSSmax), mean wall shear stress (WSSmean), and oscillatory shear index (OSI) were measured bilaterally with V-flow. Least absolute shrinkage and selection operator (LASSO) regression was used for predictor selection, and diagnostic performance was assessed via receiver operating characteristic (ROC) analysis. The correlation of WSSmean with peak systolic velocity (PSV) and blood flow (BF) was evaluated with Spearman analysis. Results: WSSmax and WSSmean were significantly higher in the study group than in the control group [study group WSSmean: median 1.48 Pa, interquartile range (IQR), 1.08-2.24 Pa; control group WSSmean: median 0.52 Pa, IQR, 0.36-0.70 Pa; P<0.001]. Within the study group, the stenosis subgroup exhibited a lower WSSmax and WSSmean compared to the non-stenosis subgroup (stenosis WSSmean: median 1.18 Pa, IQR, 0.93-1.50 Pa; non-stenosis WSSmean: median 1.65 Pa, IQR, 1.26-2.51 Pa; P<0.001). The OSI did not differ significantly between the groups (P=0.978). LASSO regression identified inner diameter, resistive index (RI), and WSSmean as the most sensitive predictors of AVF stenosis. The combined model incorporating these three parameters yielded an area under the ROC curve (AUC) of 0.806 [95% confidence interval (CI): 0.710-0.902], which was superior to any single parameter (diameter: AUC =0.721; RI: AUC =0.728; WSSmean: AUC =0.719; P<0.05 for comparison with combined model). WSSmean showed a weak positive correlation with PSV (r=0.291; P<0.01) and with BF (r=0.364; P<0.001). Conclusions: V-flow imaging was found to be feasible for assessing brachial artery WSS in patients on hemodialysis, and reduced WSSmean was associated with AVF stenosis. These findings support the potential clinical utility of V-flow-derived hemodynamic parameters for fistula surveillance.