Session P81.1

Analysis of Cardiac Cells Field Potentials Using Wavelet Transform

S Jacquir*, B Xu, T Bakir, JM Bilbault, S Binczak

Université de Bourgogne
Dijon, France

Heart rate variability (HRV) is a reliable reflection of the many physiological factors modulating the normal rhythm of the heart. It shows that the structure generating the signal is not only simply linear, but also involves nonlinear contributions. HRV corresponds to the variation over time of the period between consecutive heartbeats and is predominantly dependent on the extrinsic regulation of the heart rate (HR). In this study, the HRV is investigated at a microscopically level in a cardiac cells culture by analysing the field potential (FP) signals using a time-frequency method. A number of alternative time–frequency methods are now available for signal analysis. Among them, the wavelet transform has emerged over recent years as the most favored tool by researchers for analysing problematic signals across a wide variety of areas in science, engineering and medicine. It is especially valuable because of its ability to elucidate simultaneously local spectral and temporal information from a signal by employing a window of variable width. The aim of this work is to characterize the electrical activity of cardiac cells by applying wavelet transform on experimental signals. In first, synchronous multifocal FP recorded using a non-invasive technology based on 60 substrate-integrated microelectrode arrays (MEA; 8x8 matrix, 30 µm electrode diameter, 200 µm inter-electrode distance) are denoised using a wavelet based method. Then choosing a pattern representing the FP signal in a normal rhythm of cardiac cell, an adapted wavelet function called mother wavelet has been synthesized. Using a wavelet transform and this mother wavelet, a time–frequency decomposition of the FP train has been realized in the case of the normal and abnormal rhythms leading to extract FPs from the signal and to obtain easily characterizing parameters, such as FP duration and positions. Our results suggest that wavelet analysis provides useful information for the assessment of dynamic changes and patterns of FP train. Finally, using this method, we show that during a normal rhythm (constant frequency between FP signal), fluctuations appear in the FP duration. These local spontaneous variations in the FP duration may be a safety process protecting against microscopically discontinuous conduction, and abnormality of this natural process could contribute to the genesis of some heart arrhythmias.

(Abstract Control Number: 134)