Robust Detection of AO and IM Points in the Seismocardiogram Using CWT

Abstract

The seismocardiogram (SCG) records the mechanical vibrations resulting from cardiac movements, and it is acquired on the chest. The SCG is a non-invasive and inexpensive technique for monitoring cardiac activity. This paper propose a new method to detect the points associated with the opening of the aortic valve (AO) and isovolumic moment (IM) at the SCG, without using the reference of electrocardiogram (ECG) signal. This method uses continuous wavelet transform (CWT) as a base and a decision rule as a first approximation, followed by a fine position detection points. The performance achieved by the detector is 99% of sensitivity, and error less than 3%. Detector performance was evaluated for several wavelets, and the best results were obtained with the Daubechies wavelet of order 4. Finally, it was evaluated robustness to noise with good results. The simplicity of the proposed method allows a starting point to segment the SCG and reliable use for monitoring elderly people at home.