Hemodynamics are associated with subsequent lumen remodeling and clinical maturation of hemodialysis arteriovenous fistula

Abstract

The pathogenesis of arteriovenous fistula (AVF) maturation failure is unclear. We evaluated the associations of wall shear stress (WSS) with subsequent AVF remodeling and clinical maturation using regression models in this prospective cohort study. Participants underwent duplex ultrasound at postoperative Day 1, Week 2, and Week 6 to measure AVF blood flow rate and diameter of the draining vein and proximal artery. The median vein WSS of 602 participants decreased from Day 1 to Week 6 (from 33.4 to 21.6 dyne/cm²) but did not change noticeably for the artery (from 58.4 to 55.1 dyne/cm²). WSS was positively associated with subsequent lumen expansion, with doubling of Day-1 WSS presaging a 9% (95% confidence interval (CI) 5%-14%; P < 0.001) greater Day 1-to-Week 6 increase in vein lumen cross-sectional area and a 5% (95% CI: 1%-10%; P = 0.020) greater increase in artery lumen area. The odds of unassisted clinical maturation increased by 45% (95% CI: 11%-89%; P = 0.006) with each doubling of Day-1 vein WSS, and by 82% (95% CI: 39%-250%; P < 0.001) with each doubling of Day-1 artery WSS. These findings show that WSS was positively associated with subsequent lumen expansion and AVF unassisted clinical maturation.

Fig. 1

Postoperative fistula vein lumen diameter and wall shear stress (WSS). Box plots of vein diameters at 2, 5, 10, and 15 cm from the anastomosis (panel A), diameters averaged over these four locations (panel B), WSS at 2, 5, 10, 15 cm from the anastomosis (panel C), and WSS averaged over these four locations (panel D). The whiskers were placed 1.5 times the interquartile range beyond the first and third quartiles, and more extreme values were treated as outliers and not shown.

Fig. 2

Postoperative fistula artery lumen diameter and wall shear stress (WSS). Box plots of diameters at 2 cm from the anastomosis (panel A) and WSS (panel B). The whiskers were placed 1.5 times the interquartile range beyond the first and third quartiles, and more extreme values were treated as outliers and not shown.

Fig. 3

Associations between wall shear stress (WSS) and subsequent fistula lumen remodeling. Data on the vein are presented in panels A-C, while data on the proximal artery are presented in panels D-F. Plotted are lumen cross-sectional area ratio of Week-2 area to Day-1 area (A and D), Week-6 area to Week-2 area (B and E), and Week-6 area to Day-1 area (C and F) on y axis and the corresponding WSS in each period on the x axis. The 5^th, 10^th, 25^th, 50^th, 75^th, 90^th, and 95^th percentiles of WSS are labeled in each panel. Note that the plots do not show the entire range of WSS. The prediction is the result of a full linear-regression model (model IV) after logarithmic transformations of WSS and cross-sectional area ratios, adjusting for vein or artery diameter at the beginning of each period, baseline age, sex, race, diabetes, dialysis history, clinical center, preoperative artery and vein diameters, AVF location (forearm versus upper arm), flow-mediated dilation, and nitroglycerin-mediated dilation. A positive association between WSS and subsequent relative lumen area change was found for each time period for both vessels.

Fig. 4

Vein lumen area changes at different locations from the anastomosis with each doubling of wall shear stress (WSS). The mixed effect models were adjusted for baseline age, sex, race, diabetes, dialysis history, clinical center, preoperative artery and vein diameters, arteriovenous fistula location (forearm versus upper arm), flow-mediated dilation, and nitroglycerin-mediated dilation. The area ratio and its 95% confidence interval are presented in the y axis.

Fig. 5

Associations between wall shear stress (WSS) and subsequent arteriovenous fistula lumen remodeling according to fistula location. Plotted are the predicted remodeling presented as lumen cross-sectional area ratio of Week-6 area to Day-1 area on y axis and corresponding WSS at Day 1 in the Day 1 to Week 6 period on x axis for vein (A and C) and artery (B and D). The 5^th, 10^th, 25^th, 50^th, 75^th, 90^th, and 95^th percentiles of WSS are labeled in each panel. The prediction is the result of a linear regression model after logarithmic transformations of WSS and cross-sectional area ratios, adjusting for vein or artery diameter at Day 1, baseline age, sex, race, diabetes, dialysis history, clinical center, preoperative artery and vein diameters, arteriovenous fistula location (forearm versus upper arm), flow-mediated dilation, and nitroglycerin-mediated dilation. Associations between WSS and lumen remodeling were not different between forearm and upper-arm AVFs for both vein and artery.