Use of a Digital Stethoscope to Evaluate Arteriovenous Fistulae Before and After Intervention

By Shariff, Saad Mohammed; Haddad, Samuel; Lee, Sora; Kieu, Spencer; Mathew, George; Xi, Gang; Roy-Chaudhury, Prabir
Posted in Published Research

Background: Arteriovenous fistula (AVF) maturation failure, defined as the inability of the AVF to support dialysis via two-needle cannulation, remains a common, costly, and deleterious problem among dialysis patients, with stenosis within the venous segment a common cause. Evaluation of AVF patency and flow currently relies on imaging techniques like doppler ultrasound and fistulagrams to assess AVF dysfunction, procedures that both generally occur outside of the dialysis unit. In an attempt to develop screening tools for vascular access dysfunction that could be used in the hemodialysis unit itself, we herein present before and after phonocardiogram recordings obtained from patients undergoing AVF angioplasty for AVF maturation failure.

Methods: By physical examination, we identified the site of the arteriovenous anastomosis. We used the Eko Littman® CORE Digital Stethoscope and Eko smartphone app to obtain phonocardiogram recordings from three sites associated with the AVF: distal venous (8cm distal to the anastomosis), proximal arterial (2cm proximal to the anastomosis), and distal arterial (2cm distal to the anastomosis). De-identified recordings were labeled by location and exported prior to analysis.

Results: We observed differences in both the amplitude and profile (Fig. 1) of phonocardiogram recordings taken at the same site before and after intervention (angioplasty).

Conclusion:

  1. We have demonstrated the technical feasibility of using a portable, user-friendly, digital stethoscope and smartphone app in the setting of AVF maturation failure.
  2. Clear differences in both the amplitude and profile of AVF phonocardiograms suggest that the Eko device could be used to risk stratify patients at high risk of a failed angioplasty for AVF maturation.
  3. The Eko phonocardiograms could be an effective, low-cost screening tool for angioplasty success or failure in the setting of AVF maturation failure in the hemodialysis unit itself.

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