Effect of Noise Sources on the Averaged PQRST Morphology

摘要

We analysed noise interference on the PQRST waveform of the electro- and magnetocardiogram as recovered by an average technique. Three signals (adult A, neonatal N, and fetal F) were corrupted with breathing, electromyographic and power-line noise at different levels of the QRS amplitude. Using the correlation coefficient r, averaged PQRST patterns from corrupted signals were compared with corresponding uncorrupted templates. Lower r values were obtained at higher noise levels; this effect was more critical for the F signal. Noise sources caused different distortion; e.g. at 0.8 level and 50 averaged beats, r remained high for breathing (0.996 A, 0.995 N, 0.972 F); lower for electromyography (0.990 A, 0.972 N, 0.905 F), and even lower for power-line (0.931 A, 0.852 N, 0.574 F). Thus, to perform morphological analysis of the PQRST waveform the source, noise level and signal's nature should be considered for defining an optimal number of beats to be averaged.