Evaluation of arteriovenous fistula maturation and early prediction of clinical eligibility, using ultrasound: The Fistula Maturation Evaluation (FAME) Study.

INTRODUCTION: The study of time-related alterations of ultrasound-determined parameters during maturation, and the assessment of time to hemodynamic maturation, enabling early prediction of clinical eligibility, of hemodialysis autologous arteriovenous fistulae (AVF). METHODS: This is an observational, prospective, study of only AVF-eligible patients referred for access creation, from 02/2019 to 02/2022 (ClinicalTrials.gov identifier: NCT0473687). Brachial artery diameter (dBA), access flow volume (FV), non-augmented efferent vein diameter (dEV), resistivity index (RI), and efferent vein total wall thickness (tEV), were assessed by ultrasound. Measurements were conducted daily in the first week and repeated on days 14, 21, 30, 60, and 90, postoperatively. The primary endpoint included the documentation of serial changes of flow and structural parameters related to AVF maturation in the first 90 days of the post-operative period and maturation early prediction. Secondary endpoints included the determination of factors affecting maturation. RESULTS: One hundred one participants (mean age, 67 ± 6 years; 76 males) were enrolled. Average dBA and FV reached maximum on day 60 (5.64 ± 0.85 mm) and 90 (1.172 ± 617 mL/min), respectively. Day 7 values of dBA (5.48 ± 0.73 mm) and FV (1.039 ± 531 mL/min) did not alter significantly during the follow-up period. Parameters indicative of clinical functionality, dEV (5.82 ± 0.90 mm) and tEV (0.493 ± 0.10 mm), reached approximately 90% of maximum (6.66 ± 1.42 mm and 0.526 ± 0.11 mm), by day 14. RI reached minimum on day 30 (0.46 ± 0.09), without significant changes after day 2 (0.48 ± 0.09, p = 0.284). A significant correlation was identified, between day 7 FV and day 60 dEV (r = 0.40, p = 0.0002). A FV cut-off value ⩾657.51 mL/min, on day 7, predicted successful fistula maturation with 85% sensitivity and 100% specificity. Multivariate analysis identified female gender, age >75, diabetes, and wrist access as independent predictors of decreased values of maturation parameters. CONCLUSION: Hemodynamic maturation is completed by the first postoperative week, while AVF is clinically functional, by the second. FV can be used for early prediction of maturation.

Results of a hemodialysis vascular access routine ultrasound surveillance protocol and frequency of surveillance guided pre-emptive access maintenance interventions.

BACKGROUND: To evaluate the implementation of routine surveillance using ultrasound on hemodialysis vascular access (VA) outcomes and determine the number and frequency of corrective, surveillance-guided procedures performed. METHODS: Multicenter, prospective, observational study that includes consecutive hemodialysis patients receiving therapy from native arteriovenous fistulae (AVF) or grafts (AVG). Participants were assigned to a routine VA Color Doppler ultrasound surveillance (DUS) protocol from January 2019 to December 2021. Patients were referred for corrective procedures (endovascular or surgical) based on clinical or DUS findings (pre-emptive procedures; PEP). Primary endpoint was the estimation of primary unassisted (PUP) and secondary patency (SP) rates. Secondary endpoints were the determination of the number and frequency of PEP and VA survival rates. RESULTS: In total, 223 patients with 243 VA (192 AVF and 51 AVG) were included. Access PUP and SP rates were 83% and 93% at 12 months, 75% and 88% at 24 months, and 72% and 83% at 36 months follow-up. Autologous fistulae PUP and SP were 89% and 96% at 12 months, 81% and 93% at 24 months, and 80% and 89% at 36 months, respectively. Graft PUP and SP were 56% and 80% at 12 months, 44% and 65% at 24 months, and 39% and 54% at 36 months, respectively. In total, 56 corrective procedures (38/56 PEP; 65.5%) were performed (0.13 procedures/year), of which 34 were in AVF patients (0.09 procedures/year) and 22 in AVG patients (0.40 procedures/year). Overall, 33 VA losses occurred (0.06 failures/year), 17 in AVF (0.04 failures/year), and 16 in AVG patients (0.20 failures/year). CONCLUSION: The use of DUS resulted in the timely diagnosis of dysfunction, satisfactory overall VA survival, and patency rates, with a low PEP frequency. Randomized controlled trials are required to establish the value of DUS surveillance on access patency and whether DUS-guided interventions could improve VA outcomes.

VOLume flow assistance for optimizing outcomes of dysfunctional autologous arteriovenous fistula Angioplasty: the VOLA Pilot Study.

OBJECTIVES: To investigate the feasibility of VF-assisted angioplasty (VFA) in dysfunctional AVF using sequential intraprocedural duplex ultrasound (DUS), to utilize intraprocedural VF as a quantifiable, functional endpoint in endovascular treatment. METHODS: This prospective study included 20 consecutive patients (23 lesions; 16 men; mean age 67 ± 16 years) with dysfunctional AVF undergoing fluoroscopically guided balloon angioplasty between June 2019 and May 2020. Primary endpoints were quantification of outcome using sequential DUS VF analysis following each dilation, 6-month target lesion re-intervention (TLR)-free rate, standard technical success, procedural success (achievement of a postprocedural VF value equal (or 10% less) or superior to the baseline steady-state access), and correlation between procedural success and TLR-free rate. Secondary endpoints included 6-month lesion late lumen loss (LLL), correlation between balloon diameter used and intraprocedural VF values, and correlation between VF and LLL at 6 months follow-up. RESULTS: Mean VF increase was 168.5% ± 102.5% (range: 24.24-493.33%). Procedural success was 80% (16/20 cases). VFA improved procedural success by 20% (4/20 cases) compared to standard assessment (< 30% residual stenosis and palpable thrill). TLR-free rate was 78.3% and 67.3% at 6 and 12 months. Significantly less TLR was noted in cases of procedural success (82.4% vs. 66.7% 6 months; p = 0.041). Unweighted linear regression showed a significant positive relationship between diameter of balloon and VF (146.9 ± 42.3 mL/min VF gain per mm of balloon diameter; p = 0.001, R2 = 0.23) and a significant negative relationship between LLL and VF decline at follow-up (102.0 ± 34.6 mL/min loss per mm of LLL; p = 0.01, R2 = 0.35). Optimal VF cutoff value and percentile increase to predict access failure were 720 mL/min (sensitivity 58.3%, specificity 71.4%) and 153% (sensitivity 66.7%, specificity 85.7%), respectively. CONCLUSION: Intraprocedural VF assessment could be used to optimize AVF angioplasty. KEY POINTS: • A newly proposed functional endpoint of angioplasty in dysfunctional dialysis fistula was evaluated and angioplasty outcome was quantified using volume flow (VF) assessment with sequential intraprocedural DUS. • Intraprocedural VF assessment improved immediate procedural success; increased balloon diameter was correlated with VF gain and late lumen loss with VF decline. • Intraprocedural VF values ≥ to baseline steady-state values were correlated with less re-interventions.