Time-frequency analysis of heart sounds before and after angioplasty

Heart sounds have been recorded from patients with coronary artery disease before and after angioplasty in the cardiology department of the Royal Adelaide Hospital. We present an algorithm to decompose the recorded signals to beat cycles synchronized with electrocardiogram (ECG) and detect the most correlated cycles. Time-frequency analysis is carried out on the isolated beat cycles, and another algorithm is used to detect local maxima in the time-frequency plane. The detected maxima are then compared before and after angioplasty.