Decomposition and analysis of the second heart sound based on the matching pursuit method

In this study, the matching pursuit method (MP) was used to decompose the second heart sound S2 into a series of time-frequency atoms. From these parameterized atoms, A2 and P2 can be separated. The first two dominant frequencies of A2 were identified and used as features of a linear classifier to diagnose aortic valve abnormality. This method was applied to two sets of S2 data recorded from 28 patients with normal, and 3-4 patients with abnormal, bioprosthetic aortic valves respectively, it was found that the values of both features exhibit significant differences between the normal and abnormal set (p< 5.0e-8). Using these two features, a correct classification of 90.3% was obtained. In addition, when the Wigner distribution of S2 was calculated from the decomposed atoms and compared with a spectrogram of S2, the MP method provided better results. The study demonstrates that the MP method may be promising technique for heart sound analysis.