Seismocardiography: An alternate method to estimate electro-mechanical window

Analysis of electromechanical (E-M) window provides an early marker of several cardiovascular diseases. The E-M window is defined as the duration between the electrical systole (QT) and the mechanical systole (QS2). Traditional methods for the estimation of the electrical systole and the mechanical systole are electrocardiography (ECG) and phonocardiography (PCG). PCG is a widely used method due its features such as portability and cost effectiveness. However, it needs to be improvise in terms of its size and weight, to make it convenient to wear for long-term. Further, the PCG signal is susceptible to various noises, which limits its use in clinical environment. Henceforth, in this paper, we presented a novel system to estimate the E-M window using seismocardiogaphy (SCG) in replacement of the PCG. The SCG uses a sensor called accelerometer, which is small in size and low weight and hence it is convenient to wear. Furthermore, it does not require a microphone, as required in case of the PCG, and hence it is robust to environmental noises. We analysed the performance of the proposed system compared to the PCG, for the estimation of the E-M window. For this purpose ECG, PCG, and SCG signals are acquired simultaneously, for 10 subjects and then validated the obtained results using Bland-Altman plots. Results show that the proposed method is a suitable alternative to estimate the E-M window.