(H-293) Using the Second Heart Sound as a Noninvasive Assessment of Markers Indicative of Heart Failure

Introduction:: Heart failure (HF) is a leading cause of cardiovascular morbidity. Patients with HF require regular monitoring to assess therapeutic efficacy and prevent hospitalization. Current technology to remotely monitor HF patients has a high cost and requires implantation, which makes it inaccessible to some patients. Elevated right ventricular (RV) systolic pressure is an indicator of worsening HF. Second heart sound (S2) splitting occurs from the asynchronous closures between aortic (A2) and pulmonary valves (P2). Increases in RV volume or pressure can affect S2 split time. In this study, we assess whether S2 duration correlates to RV pressure and determine the feasibility of using the S2 as a tool to noninvasively monitor HF.


Materials and Methods:: Adult C57Bl/6J mice were either placed on a normal-chow diet or a high-adenine diet, which induces chronic kidney disease (CKD) and CKD-induced cardiac dysfunction. Control (n=80) and Adenine-fed (n=80) mice were placed on either a normal chow or Adenine diet, respectively. Endpoint measures were collected at either 3, 6, 9 or 12 weeks after administering the diet. Phonocardiogram (PCG) signals were recorded using a digital stethoscope and used to determine S2 duration. Right-heart catheterization was performed to evaluate cardiac function. Levels of cardiac biomarkers (CTnI, and NT-proBNP) were identified and correlated to measures of cardiac function and S2 duration

Results, Conclusions, and Discussions:: Data from 108 mice show that the Adenine mice have markers indicative of HF as early as week 6. Adenine mice (25.92 ± 8.48 mmHg) had significantly higher RV pressure (Figure 1a) at week 6 when compared to control mice (19.10 ± 2.81 mmHg). The Adenine group had significantly decreased S2 duration at week 12 (Figure 1b). The S2 duration and RV pressure had a weak linear correlation (r=-0.511) (Figure 1c). However, sensitivity and specificity for detecting high RV pressure ( >25 mm Hg) were 91.67% (11/12) and 85.71% (24/27), respectively, for S2 duration (cutoff value: 14ms). So far, our data shows the potential of using S2 duration as a noninvasive measure of increased RV pressure. Future analysis will assess whether S2 characteristics correlate to cardiac biomarkers and function. The overall study outcomes could yield low-cost, point-of-care techniques to assess HF in underserved populations.


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