Time-frequency representation of systolic murmurs using wavelets

This paper describes a signal processing technique aimed at complementing cardiac auscultation in the detection of heart valve disease. The method provides a means of keeping objective records by analysing the characteristics of the murmurs. The Continuous Wavelet Transform (CWT) is calculated to extract Time-Frequency (TF) information of systolic murmurs from 10 patients diagnosed as suffering from Aortic Stenosis (AS). Results from the Morlet Wavelet are presented. The coefficients of the CWT are depicted in a three-dimensional diagram and the dominant frequencies are highlighted in order to provide a simple representation which shows the variation in frequency and intensity during the murmur. Some interesting observations show a characteristic rising and falling tones suggesting different degrees of severity.