Removing ECG noise from surface EMG signals using adaptive filtering

• Published in: Neuroscience letters Vol. 462; no. 1; pp. 14 - 19
• Main Authors: Lu, Guohua, Brittain, John-Stuart, Holland, Peter, Yianni, John, Green, Alexander L., Stein, John F., Aziz, Tipu Z., Wang, Shouyan
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 02.10.2009; Elsevier
• Subjects: Adaptive filter; Adaptive noise cancellation; Algorithms; Biological and medical sciences; Dystonia; Electrocardiogram; Electrocardiography - methods; Electromyography - methods; Fundamental and applied biological sciences. Psychology; Heart - physiology; Humans; Least-Squares Analysis; Muscle, Skeletal - physiopathology; Recursive-least-square; Signal Processing, Computer-Assisted; Surface electromyogram; Torticollis - physiopathology; Vertebrates: nervous system and sense organs; Surface electromyogram; Dystonia; Adaptive filter; Electrocardiogram; Adaptive noise cancellation; Recursive-least-square; Noise; Electrophysiology; Electromyography
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2009.06.063

Surface electromyograms (EMGs) are valuable in the pathophysiological study and clinical treatment for dystonia. These recordings are critically often contaminated by cardiac artefact. Our objective of this study was to evaluate the performance of an adaptive noise cancellation filter in removing electrocardiogram (ECG) interference from surface EMGs recorded from the trapezius muscles of patients with cervical dystonia. Performance of the proposed recursive-least-square adaptive filter was first quantified by coherence and signal-to-noise ratio measures in simulated noisy EMG signals. The influence of parameters such as the signal-to-noise ratio, forgetting factor, filter order and regularisation factor were assessed. Fast convergence of the recursive-least-square algorithm enabled the filter to track complex dystonic EMGs and effectively remove ECG noise. This adaptive filter procedure proved a reliable and efficient tool to remove ECG artefact from surface EMGs with mixed and varied patterns of transient, short and long lasting dystonic contractions.