Beat-to-beat noise removal in non-invasive His-bundle electrocardiogram.

His-bundle electrocardiogram micropotentials are usually obtained by serial-signal averaging, because no acceptable, satisfactory solution for beat-by-beat removal of power-line interference and electromyographic noise has been found. A method has been developed for surface beat-to-beat His-bundle potential recovery, with the hypothesis that no distortion in the signal shape is admissible. It is based on consecutive power-line interference subtraction and wavelet-domain electromyographic noise suppression, modified to match the strict criteria for detecting low-amplitude His potentials. The beat-to-beat wavelet-domain Wiener filtering uses a pilot signal estimate obtained from a limited number (around 20) of heart beat averages. The method resulted in an improvement of more than 4.5 dB in the signal-to-noise ratio and more than 20% reduction in mean absolute error, both measured along the P-Q segment. It is applicable for ECG signals contaminated by moderate electromyogram noise, with an initial signal-to-noise ratio of 15 dB or higher.