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Abstract: SA-PO015

Differences in Early Hemodynamics Between Arteriovenous Fistulas and Grafts in Porcine Models

Session Information

  • Bioengineering
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Bioengineering

  • 300 Bioengineering

Authors

  • Vranes, Samantha, The University of Utah, Salt Lake City, Utah, United States
  • Fairbourn, Brayden, The University of Utah, Salt Lake City, Utah, United States
  • Northrup, Hannah M., The University of Utah, Salt Lake City, Utah, United States
  • He, Yong, University of Florida, Gainesville, Florida, United States
  • Berceli, Scott A., University of Florida, Gainesville, Florida, United States
  • Cheung, Alfred K., The University of Utah, Salt Lake City, Utah, United States
  • Shiu, Yan-Ting Elizabeth, The University of Utah, Salt Lake City, Utah, United States
Background

The formation of neointimal hyperplasia (NH) leads to shortened patency rates for long-term hemodialysis vascular accesses – the arteriovenous fistula (AVF) and the arteriovenous graft (AVG). NH is more severe in AVG than AVF in patients, though the reasons are not yet completely understood and may be multifactorial. Blood flow parameters (e.g., wall shear stress (WSS)) are linked to NH formation. Here we investigated and compared hemodynamics and NH in porcine AVF and AVG models. We hypothesized that a higher WSS value leads to less NH formation and better vascular access outcomes. Therefore, we compared early flow hemodynamics to late NH formation.

Methods

Carotid-jugular fistulas and grafts were created in young pigs (n=3 each). They were scanned by magnetic resonance imaging (MRI) 1 week after surgery. Black-blood and phase-contrast velocity MRI scans were used to calculate cross-sectional area (CSA) and perform computational fluid dynamics to analyze hemodynamic parameters, including flow rate, velocity, WSS, and oscillatory shear index (OSI). Since NH formation occurs near the venous anastomosis, we focused on the proximal venous segments closer to the anastomosis. Early hemodynamics were obtained at week 1. NH was visualized at weeks 4-6 by histology.

Results

The venous CSA in the AVFs (mean±SD, 14.87±7.38 mm2) and the AVGs (19.58±5.63 mm2) were similar (p=0.06) at week 1. However, the AVF venous flow rate (532.24±87.27 mL/min), velocity (67.70±20.02 cm/s), and WSS (196.68±91.12 dyn/cm2) were significantly larger than the AVG (346.49±127.92 mL/min, 31.80±15.65 cm/s, 73.59±51.53 dyn/cm2) (p=0.01 – 0.02) at week 1. OSI in the AVF and AVG were similar (0.031±0.029 vs. 0.027±0.03 rotation/s; p=0.07). Histology showed that the AVG had more NH than the AVF at weeks 4-6.

Conclusion

Our results reveal differences between the AVF and AVG in early hemodynamics and late NH formation. Specifically, AVFs had less NH than AVGs in our porcine models, similar to human. Our results suggest that higher WSS values in AVF may prevent NH formation and lead to better vascular access outcomes. Future research can consider hemodynamic parameters at later time points, in other regions of the vessel (i.e. the arterial anastomosis), and fluid-structure interactions.

Funding

  • NIDDK Support