A Cost-effective, Patient-facing Electronic Stethoscope For Telemedical Cardiac Auscultation

INTRODUCTION: The COVID19 pandemic spurred an unprecedented growth in telehealth utilization across medical specialties which challenged providers to adapt their standard history and physical protocols for the virtual realm. Heart failure clinicians could readily translate some aspects of physical examination such as jugular venous distention and lower extremity edema assessment over video incorporating bendopnea to gain additional information. However, objective data for clinicians to rely on and guide therapy was often missing. A myriad of technology is available to bridge this gap ranging from simple wearables to invasive hemodynamic monitors though come with varying price tags and avenues of accessibility. OBJECTIVE: We sought to develop an affordable, patient-facing electronic stethoscope of comparable quality to those existing that could seamlessly integrate with any telemedicine platform for real-time or asynchronous clinician review. METHODS: A rigorous design process guided by clinician and patient input generated nearly 100 concepts stratified through a pugh decision matrix in reference to an existing product, the Eko Core, to decide on the most suitable design - the AusculBand. With the form factor of a wrist-band, the AusculBand encases a custom bell with a high fidelity microphone and unique circuitry to sit comfortably in the palm of a user's hand to facilitate self-auscultation over the chest wall for real-time clinician review via telemedicine. Recognizing cardiac sounds to fall between 20 Hz and 2000 Hz, frequency response testing was conducted to determine the cut-off frequency of the AusculBand. With knowledge of an industry standard signal-to-noise ratio of 10.31 dB, a simple comparative study was devised between our novel AusculBand and the commercial Eko Core. With each device, a single-user in replicative fashion collected cardiac signals from the chest wall and background noise from the bicep to generate signal-to-noise ratio readouts and compare overall sound quality. RESULTS: In response to frequency testing, the AusculBand was found to attenuate frequencies higher than 1997 Hz when testing a signal that swept through a range of 0 to 3,000 Hz at a constant amplitude. This result was within 0.2% of the 2000 Hz upper-limit of cardiac sounds and surpassing our design input goal of ≤ 1%. Signal-to-noise ratio analysis revealed 27.29 dB for the AusculBand and 24.02 dB for the Eko Core each exceeding the industry standard of 10.31 dB. Head-to-head comparison revealed the AusculBand achieved nearly double the loudness of the Eko Core. The projected price of the AusculBand is $80. The Eko Core is currently marketed at $350. CONCLUSIONS: The AusculBand is a cost-effective, patient-facing electronic stethoscope that surpasses industry standards in signal-to-noise ratio and is readily adaptable to popular telemedicine platforms. Additional modification is underway to add a single-lead electrocardiogram to bolster the device as an all-in-one, affordable and accessible telemedicine tool for cardiac analysis.