Acoustic Detection of Coronary Occlusions before and after Stent Placement Using an
Electronic Stethoscope
Andrei Dragomir 1, Allison Post 1, Yasemin
M. Akay 1, Hani Jneid 2,3, David Paniagua 2,3,Ali Denktas 2,3, Biykem Bozkurt
2,3 and Metin Akay 1,*1 Department of Biomedical Engineering, University of
Houston, Houston, TX 77204, USA;
Andrei.Drag@gmail.com (A.D.);
Allison.Post@central.uh.edu (A.P.); ymakay@uh.edu (Y.M.A.)2 Winters Center for
Heart Failure Research, The Michael E. DeBakey VA Medical Center, Houston, TX
77030,USA; jneid@bcm.edu (H.J.); dpaniagua@bcm.edu (D.P.); ali.denktas@bcm.edu
(A.D.);bbozkurt@bcm.edu (B.B.)
3 Cardiovascular Research Institute, Baylor
College of Medicine, Houston, TX 77030, USA
* Correspondence: makay@uh.edu; Tel.:
+1-832-842-8860
Academic Editors: Raúl Alcaraz Martínez and
Kevin H. Knuth
Received: 27 April 2016; Accepted: 23 July
2016; Published: 29 July 2016
Abstract: More than 370,000 Americans die
every year from coronary artery disease (CAD).Early detection and treatment are
crucial to reducing this number. Current diagnostic and disease-monitoring methods are invasive,
costly, and time-consuming. Using an electronic stethoscope and spectral and
nonlinear dynamics analysis of the recorded heart sound, we investigated the
acoustic signature of CAD in subjects with only a single coronary occlusion
before and after stent placement, as well as subjects with clinically normal
coronary arteries. The CAD signature was evaluated by estimating power ratios
of the total power above 150 Hz over the total power below 150 Hz of the FFT of
the acoustic signal. Additionally, approximate entropy values were
estimated to assess the differences induced
by the stent placement procedure to the acoustic signature of the signals in the
time domain. The groups were identified with this method with 82% sensitivity and
64% specificity (using the power ratio method) and 82% sensitivity and 55%
specificity (using the approximate entropy). Power ratios and approximate
entropy values after stent placement are not statistically different from those
estimated from subjects with no coronary occlusions. Our approach
demonstrates that the effect of stent
placement on coronary occlusions can be monitored using an electronic
stethoscope.