Pilot study on the separability of the native heart sounds and device support noise in patients implanted with left ventricular assist devices

The assessment of heart sounds in patients with Left Ventricular Assist Devices (LVADs) presents significant challenges. The persistent mechanical hum produced by the pump obscures the natural heart sounds, complicating the detection of critical issues such as valve dysfunction, suction events, and abnormal blood flow patterns. Currently, echocardiography is frequently employed for monitoring; however, its application is not practical for home environments. This study explores the potential of phonocardiography (PCG) as a non-invasive method for monitoring cardiac function in patients with LVADs, specifically by accurately estimating cardiac time intervals (CTIs). PCG signals were collected from patients equipped with the HM3 LVAD, Abbott™. We employed Power Spectral Density (PSD) and Time-Frequency (TF) analysis to identify the dominant frequency components produced by the pump and their respective timings. A template-matching technique was applied to isolate the pulsatility mode of the LVAD from the PCG, thereby enabling the detection of native heart sounds. From this refined signal, we extracted the closure times of the heart valves. Our approach successfully differentiated native heart sounds from the in-band noise generated by the device, demonstrating the efficacy of PCG in LVAD patients. The identified CTIs provide important insights into the heart's compensatory mechanisms under these conditions and hold promise for continuous, non-invasive cardiac monitoring. This study presents the significant potential of PCG as an alternative to echocardiography for evaluating cardiac health in LVAD patients. Future research should focus on refining automated detection algorithms and validating this technique across larger patient populations to enhance its feasibility for monitoring in home settings.Clinical Relevance- This study provides clinicians with a non-invasive method to assess cardiac function in LVAD patients, overcoming issues from pump noise. Phonocardiography helps detecting complications early and reduces reliance on echocardiography, allowing for easier home monitoring and improved patient management.