Maturation Rates of Arteriovenous Fistulas Using Small Veins in the Era of Endovascular Interventions.

Background: Traditional practice suggests the abandonment of veins smaller than 3 mm in diameter for arteriovenous fistula (AVF) creation because of a low rate of maturation. This study aims to show that with balloon-assisted maturation (BAM), undersized veins can be used to create functional AVFs with a high rate of success.

Methods: All patients who underwent AVF creation between 2014 and 2018 at a tertiary academic medical center were retrospectively reviewed. The patients without preoperative vein mapping, those who failed to follow-up, and the patients who were not on dialysis were excluded. A fistula was considered to be mature if it was successfully cannulated for dialysis. A total of 596 patients were identified for analysis. The cohort was divided into the small-vein group (SVG, <2.5 mm) and large-vein group (LVG, ≥2.5 mm) based on preoperative vein size. Categorical variables were analyzed with the chi-squared test for their association with maturation status. Continuous variables were analyzed with the Wilcoxon rank sum test. A P-value less than 0.05 was considered significant.

Results: In the study cohort, 61.9% of the patients were male, with an average age of 62.8 ± 13.7 years, and an average preoperative vein size of 2.9 ± 1.1 mm. With similar demographic distribution, the participants in the SVG (n = 216) had significantly smaller preoperative vein size of 1.9 ± 0.4 mm than the patients in the LVG (n = 380), 3.5 ± 0.8 mm (P = 0.001). There were significantly more radio-cephalic AVFs created in the SVG (77.8% versus 48.7%, P < 0.0001). The overall maturation rate was 83.1% (n = 495), 219 fistulas (36.7%) matured primarily and 276 (46.3%) required interventions. Ninety-one percent of the patients required only 1 or 2 BAMs to achieve maturation. The SVG achieved a maturation rate of 75.9% as compared with 87.1% in the LVG (P = 0.002). A significantly higher number of patients in the SVG required BAM for maturation as compared with the LVG (67.7% versus 49.9%, P = 0.0002); however, there was no difference in the average number of BAMs required for fistula maturation between the groups (1.5 ± 0.8 for the SVG vs. 1.4 ± 0.7 for the LVG). In multivariable logistic regression analysis, vein size ≥2.5 mm (odds ratio (OR) = 2.11, confidence interval (CI): 1.36-3.27, P = 0.0009) and male sex (OR = 2.30, CI: 1.49-3.57, P = 0.0002) were independent predictors of maturation.

Conclusions: Small veins can be used for AVF creation with lower but still favorable maturation rates using BAM interventions, especially in male patients. This practice can increase the creation of autogenous dialysis access and potentially reduce complications related to prosthetic dialysis access.