The Role of Duplex Ultrasound in Assessing AVF Maturation

Background

Arteriovenous fistulas (AVFs) are favored for hemodialysis (HD) access. However, in many instances, AVFs fail to mature. We examined the utility of postoperative color duplex ultrasound (CDU) in assessing AVF maturation and determining the need for balloon-assisted maturation (BAM).

Methods

A total of 633 patients underwent AVF creation at a single institution from 2015 to 2018. A total of 339 patients (54%) underwent CDU at a median of 8 weeks postoperatively. We collected the following parameters: vein diameter, volume flow (VF), peak systolic velocities in arterial inflow and venous outflow, and presence of stealing branches. A peak systolic velocity ratio (SVR) of ≥2 correlated with ≥50% stenosis in venous outflow, and SVR ≥3 correlated with ≥50% stenosis at the anastomosis. AVFs were considered mature when they were successfully cannulated on dialysis. A generalized linear mixed model (GLMM) was created to compare duplex criteria associated with successful use of AVF (maturation) to those AVFs that required further intervention or failed to mature. Fistulography images, the current gold standard, were compared with findings from CDU studies to determine validity of the duplex ultrasound.

Results

Of the 339 AVFs with postoperative CDU, 31.3% matured without interventions, 38.3% required BAM, 9.7% thrombosed, and the remaining patients were not yet on HD. Based on GLMM analysis, the probability of AVF maturation increases if CDU demonstrated one of the following: the vein diameter is ≥ 6 (odds ratio [OR] = 38.7), no evidence of stenosis in the venous outflow tract (OR = 35.6), no stealing branches (OR = 21.6) and VF ≥ 675 (OR = 5.0). Fistulography was performed in 195 patents. Sensitivity and specificity for each are as follows: vein diameter (84.3%, 28.6%), stenosis (59.3%, 78.8%), and stealing branches (20.7%, 92.7%).

Conclusions

Postoperative CDU should be considered routine to correct anatomical findings that might limit AVF maturation and identify the need for further interventions.