Quantification of Systolic Time Intervals Using Continuous Wavelet Transform of Electrocardiogram and Phonocardiogram Signals

There are a number of methods and diagnostic tools for assessing the health of the heart. The systolic time intervals (STI) have been clinically useful parameters representing cardiac cycle and measuring the ventricular performance. In this study, a continuous wavelet transform (CWT) based approach for quantifying the systolic time intervals, in particular, the pre-ejection period (PEP) and the left ventricular ejection time (LVET), using electrocardiogram (ECG) and phonocardiogram (PCG) signals are proposed. The proposed CWT-based STI quantification approach is composed of three main stages: ECG signal processing, PCG signal processing, and computation of the systolic time intervals. The proposed CWT-based STI quantification approach is validated using ECG and PCG data recorded from both healthy subjects and subjects suffering from various cardiovascular diseases. The computational results suggest that the proposed CWT-based STI quantification approach has a considerable capability for clinical applications. The means of average absolute errors on PEP and LVET quantifications are, respectively, 13.4251 ms and 27.1348 ms. The best total score achieved is 868.9192.