A new alignment method based on the wavelet multi-scale cross-correlation for noisy high resolution ECG records

The coherent signal averaging process requires an accurate estimation of the fiducial point in all beats to be averaged. The temporal cross-correlation between the detected beat and a template beat is the typical alignment method used with high-resolution ECG (HRECG) records. However, this technique does not produce a precise fiducial mark in records with high noise levels. In this study, we propose a new alignment method based on the multi-scale cross-correlation between the wavelet transforms of the template and the detected beat, respectively. The wavelet and temporal methods were tested for several simulated records corrupted with white noise and electromyographic (EMG) noise of different RMS levels. The results indicate that wavelet alignment method produces a lower trigger jitter than the temporal method in all tests. We conclude that the proposed alignment method can be used in records with high noise levels, like those found in Holter HRECG systems.