Predicting computed tomography angiography-measured arteriovenous fistula anastomosis angles using intraoperative non-contrast measurements: a prospective validation study
Year: 2026
Type: article
Study design: Observational Study
Abstract: The anastomotic angle is a modifiable determinant of arteriovenous fistula (AVF) hemodynamics, maturation, and patency. Postoperative assessment typically relies on computed tomography angiography (CTA); however, factors such as contrast exposure, radiation, and cost limit its utility for repeated evaluations. In this study, we derived a correction factor for CTA-measured anastomotic angles. The primary aim was to validate the measurement method, rather than to establish a direct link between the angle and clinical outcomes. This study collected intraoperative measurements from patients undergoing AVF surgeries and used these data to construct a predictive model for CTA-measured anastomosis angles. The model was validated using 20% of the data, with the remaining data used for model fitting. Bootstrap resampling (1,000 samples) was employed to estimate the mean squared error (MSE) and confidence intervals. The Bland-Altman plot indicated a mean difference of −16.90 between CTA and intraoperative measurements, with the majority of data points falling within the 95% limits of agreement. The Intraclass Correlation Coefficient was 0.79, suggesting acceptable reliability despite notable bias, while the Concordance Correlation Coefficient was 0.45, reflecting the impact of bias. Bootstrap validation yielded a mean MSE of 24.58 with a standard deviation of 15.17. The 95% percentile confidence interval was [2.66, 51.85]. This study provides a preliminary adjustment estimate to bridge the gap between intraoperative and CTA-measured angles. While not a fully developed predictive framework, this correction factor offers a practical, radiation-free method for surgeons to approximate the final anastomotic configuration. What was knownThe anastomotic angle in radiocephalic arteriovenous fistulas (AVFs) is a critical modifiable surgical parameter potentially influencing hemodynamics, maturation, and patency rates, with moderate angles (30°–70°) often preferred.Postoperative angle assessment typically requires computed tomography angiography (CTA), which involves contrast agents, radiation exposure, high costs, and patient reluctance, limiting large-scale or repeated studies.No validated noninvasive method existed to correlate intraoperative measurements with postoperative angles, creating a gap for practical, real-time surgical guidance and follow-up. The anastomotic angle in radiocephalic arteriovenous fistulas (AVFs) is a critical modifiable surgical parameter potentially influencing hemodynamics, maturation, and patency rates, with moderate angles (30°–70°) often preferred. Postoperative angle assessment typically requires computed tomography angiography (CTA), which involves contrast agents, radiation exposure, high costs, and patient reluctance, limiting large-scale or repeated studies. No validated noninvasive method existed to correlate intraoperative measurements with postoperative angles, creating a gap for practical, real-time surgical guidance and follow-up. This study addsIntraoperative manual measurements of AVF anastomotic angles show a consistent systematic bias (−16.90°) compared to CTA but remain clinically acceptable (ICC = 0.79), enabling prediction via a simple linear model: CTA angle = Surgical angle − 16.90°.Bootstrap validation confirmed the model’s reliability (mean MSE = 24.58), with 70% of adjusted angles aligning within the same ordinal group as CTA measurements, offering a radiation-free alternative for angle assessment.The discrepancy arises partly from surgical techniques (e.g., vein displacement during wound closure) and postoperative changes, highlighting the need to account for these factors when interpreting angles. Intraoperative manual measurements of AVF anastomotic angles show a consistent systematic bias (−16.90°) compared to CTA but remain clinically acceptable (ICC = 0.79), enabling prediction via a simple linear model: CTA angle = Surgical angle − 16.90°. Bootstrap validation confirmed the model’s reliability (mean MSE = 24.58), with 70% of adjusted angles aligning within the same ordinal group as CTA measurements, offering a radiation-free alternative for angle assessment. The discrepancy arises partly from surgical techniques (e.g., vein displacement during wound closure) and postoperative changes, highlighting the need to account for these factors when interpreting angles. Potential impactStandardization of Vascular Access Protocols: This approach could be integrated into clinical guidelines for vascular access surgery, facilitating the standardization of anastomosis techniques and reducing variability between surgeons.Intraoperative Decision Support: By providing real-time feedback, the model could serve as a decision-support tool during surgery, helping surgeons achieve target angles (e.g., 40°–50°), which have been previously associated with improved patency in other studies.Cost-Effective Monitoring: The method could facilitate frequent angle monitoring in dialysis centers, reducing the need for expensive and potentially risky CTA scans while maintaining quality control over fistula maturation. Standardization of Vascular Access Protocols: This approach could be integrated into clinical guidelines for vascular access surgery, facilitating the standardization of anastomosis techniques and reducing variability between surgeons. Intraoperative Decision Support: By providing real-time feedback, the model could serve as a decision-support tool during surgery, helping surgeons achieve target angles (e.g., 40°–50°), which have been previously associated with improved patency in other studies. Cost-Effective Monitoring: The method could facilitate frequent angle monitoring in dialysis centers, reducing the need for expensive and potentially risky CTA scans while maintaining quality control over fistula maturation.
Source: Figshare
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7204241576