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Kidney Week

Abstract: PO1344

Assessment of Arteriovenous Fistula Dysfunction with Access Stenosis in Hemodialysis Patients Using Smartphone Videos

Session Information

  • Vascular Access
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

  • 704 Dialysis: Vascular Access

Authors

  • Wang, Lin-Chun, Renal Research Institute, New York, New York, United States
  • Zhu, Fansan, Renal Research Institute, New York, New York, United States
  • Thwin, Ohnmar, Renal Research Institute, New York, New York, United States
  • Tisdale, Lela, Renal Research Institute, New York, New York, United States
  • Tao, Xia, Renal Research Institute, New York, New York, United States
  • Maheshwari, Vaibhav, Renal Research Institute, New York, New York, United States
  • Cherif, Alhaji, Renal Research Institute, New York, New York, United States
  • Shtaynberg, Norbert, Azura Vascular Care, New York, New York, United States
  • Preddie, Dean C., Azura Vascular Care, New York, New York, United States
  • Thijssen, Stephan, Renal Research Institute, New York, New York, United States
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
Background

Hemodynamically relevant stenoses in arteriovenous fistulas (AVF) lead to a reduction in access flow rate (Qa). We hypothesized that these changes in blood flow patterns may be detectable in video recordings done with commercially available smartphones.

Methods

We studied HD patients with AVF dysfunction requiring balloon angioplasty. One-minute video recordings of the skin above the AVF and Qa measurements were conducted before and after the intervention by an iPhone 6S. Qa was measured by HVT100 Transonic flowmeter. Degree of stenosis was assessed by angiography. Frame-to-frame pixel changes in video images were amplified; time-domain data were transformed into the frequency-domain signals. Fifty random 10-second segments were sampled per one-minute video, and the frequency with the lowest magnitude (Fmin) was determined in each sample (Fig. 1). The average Fmin was assessed for its association with the degree of stenosis.

Results

Ninety subjects were studied (63±14 years, HD vintage 4.1±3.5 years). Post-intervention Qa (1638±714 ml/min) was on average 1.23-fold higher than pre-intervention Qa (1373±684 ml/min; P<0.01, paired t-test). Subjects were grouped by degree of stenosis, and the number of subjects in each category is shown in Fig. 1B. Higher degrees of stenosis were associated with greater increases in Qa from before to after the intervention (Fig. 1C). Interestingly, the degree of AVF stenosis was also positively related with the change in Fmin from before to after the intervention (Fig. 1D).

Conclusion

Smartphone video recordings of AVF appear to contain frequency-domain information that correlates with hemodynamic changes caused by AVF stenoses. While the Fmin metric employed in our analysis is not ideal, these results should encourage the quest for other parameters that exhibit higher correlations with vascular access dysfunction, allowing timely referrals and avoidance of emergency interventions.