A fixed-lag Kalman smoother to filter power line interference in electrocardiogram recordings

G.J.J. Warmerdam, R. Vullings, L. Schmitt, J.O.E.H. van Laar, J.W.M. Bergmans

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Objective: Filtering power line interference (PLI) from electrocardiogram (ECG) recordings can lead to significant distortions of the ECG and mask clinically relevant features in ECG waveform morphology. The objective of this study is to filter PLI from ECG recordings with minimal distortion of the ECG waveform. Methods: In this paper, we propose a fixed-lag Kalman smoother with adaptive noise estimation. The performance of this Kalman smoother in filtering PLI is compared to that of a fixed-bandwidth notch filter and several adaptive PLI filters that have been proposed in the literature. To evaluate the performance, we corrupted clean neonatal ECG recordings with various simulated PLI. Furthermore, examples are shown of filtering real PLI from an adult and a fetal ECG recording. Results: The fixed-lag Kalman smoother outperforms other PLI filters in terms of step response settling time (improvements that range from 0.1 to 1 s) and signal-to-noise ratio (improvements that range from 17 to 23 dB). Our fixed-lag Kalman smoother can be used for semi real-time applications with a limited delay of 0.4 s. Conclusion and Significance: The fixed-lag Kalman smoother presented in this study outperforms other methods for filtering PLI and leads to minimal distortion of the ECG waveform.

Original languageEnglish
Article number7738541
Pages (from-to)1852-1861
Number of pages10
JournalIEEE Transactions on Biomedical Engineering
Issue number8
Early online date8 Nov 2016
Publication statusPublished - 1 Aug 2017


  • Electrocardiography
  • Kalman filter (KF)
  • Kalman smoother (KS)
  • Power line interference (PLI)


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