Enhancement of low-quality fetal electrocardiogram based on time-sequenced adaptive filtering

AbstractExtraction of a clean fetal electrocardiogram (ECG) from non-invasive abdominal recordings is one of the biggest challenges in fetal monitoring. An ECG allows for the interpretation of the electrical heart activity beyond the heart rate and heart rate variability. However, the low signal quality of the fetal ECG hinders the morphological analysis of its waveform in clinical practice. The time-sequenced adaptive filter has been proposed for performing optimal time-varying filtering of non-stationary signals having a recurring statistical character. In our study, the time-sequenced adaptive filter is applied to enhance the quality of multichannel fetal ECG after the maternal ECG is removed. To improve the performance of the filter in cases of low signal-to-noise ratio (SNR), we enhance the ECG reference signals by averaging consecutive ECG complexes. The performance of the proposed augmented time-sequenced adaptive filter is evaluated in both synthetic and real data from PhysioNet. This evaluation shows that the suggested algorithm clearly outperforms other ECG enhancement methods, in terms of uncovering the ECG waveform, even in cases with very low SNR. With the presented method, quality of the fetal ECG morphology can be enhanced to the extent that the ECG might be fit for use in clinical diagnostics. Graphical abstractThe extracted fetal ECG signals from non-invasive abdominal recordings still contain a substantial amount of noise. The time-sequenced adaptive filter provides a relatively accurate estimate of the underlying fetal ECG signal when the quality of the reference channels is enhanced prior to filtering.

[1]  Gang Wang,et al.  An efficient semi-blind source extraction algorithm and its applications to biomedical signal extraction , 2009, Science in China Series F: Information Sciences.

[2]  Sylvain Sardy.  Minimax threshold for denoising complex signals with Waveshrink , 2000, IEEE Trans. Signal Process..

[3]  Bernard Widrow,et al.  Multichannel adaptive filtering for signal enhancement , 1981 .

[4]  B. Widrow,et al.  Adaptive noise cancelling: Principles and applications , 1975 .

[5]  Teresa H. Y. Meng,et al.  Normalized data nonlinearities for LMS adaptation , 1994, IEEE Trans. Signal Process..

[6]  D L Kirk,et al.  Can fetal electrocardiography improve the prediction of intrapartum fetal acidosis? , 1986, British journal of obstetrics and gynaecology.

[7]  Jeffrey M. Hausdorff,et al.  Physionet: Components of a New Research Resource for Complex Physiologic Signals". Circu-lation Vol , 2000 .

[8]  Reza Sameni,et al.  Noninvasive fetal ECG: The PhysioNet/Computing in Cardiology Challenge 2013 , 2013, Computing in Cardiology 2013.

[9]  B. Widrow,et al.  The time-sequenced adaptive filter , 1981 .

[10]  Hamid Hassanpour,et al.  Fetal ECG Extraction Using Wavelet Transform , 2006, 2006 International Conference on Computational Inteligence for Modelling Control and Automation and International Conference on Intelligent Agents Web Technologies and International Commerce (CIMCA'06).

[11]  Gari D Clifford,et al.  An open-source framework for stress-testing non-invasive foetal ECG extraction algorithms , 2016, Physiological measurement.

[12]  Christian Jutten,et al.  Fetal ECG Extraction by Extended State Kalman Filtering Based on Single-Channel Recordings , 2013, IEEE Transactions on Biomedical Engineering.

[13]  Ee-Chien Chang,et al.  Blind separation of fetal ECG from single mixture using SVD and ICA , 2003, Fourth International Conference on Information, Communications and Signal Processing, 2003 and the Fourth Pacific Rim Conference on Multimedia. Proceedings of the 2003 Joint.

[14]  Hagen Malberg,et al.  Robust fetal ECG extraction and detection from abdominal leads , 2014, Physiological measurement.

[15]  Alberto Macerata,et al.  A multi-step approach for non-invasive fetal ECG analysis , 2013, Computing in Cardiology 2013.

[16]  G. Saha,et al.  Fetal ECG extraction from single-channel maternal ECG using singular value decomposition , 1997, IEEE Transactions on Biomedical Engineering.

[17]  Julien Oster,et al.  Non-invasive FECG extraction from a set of abdominal sensors , 2013, Computing in Cardiology 2013.

[18]  Yanjun Zeng,et al.  Research of fetal ECG extraction using wavelet analysis and adaptive filtering , 2013, Comput. Biol. Medicine.

[19]  K G Rosén,et al.  STAN--the Gothenburg model for fetal surveillance during labour by ST analysis of the fetal electrocardiogram. , 1989, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[20]  Chunlan Yang,et al.  Fetal ECG extraction based on adaptive linear neural network , 2010, 2010 3rd International Conference on Biomedical Engineering and Informatics.

[21]  Earl R. Ferrara,et al.  Fetal Electrocardiogram Enhancement by Time-Sequenced Adaptive Filtering , 1982, IEEE Transactions on Biomedical Engineering.

[22]  Hagen Malberg,et al.  Maternal signal estimation by Kalman filtering and Template Adaptation for fetal heart rate extraction , 2013, Computing in Cardiology 2013.

[23]  Zhenwei Shi,et al.  Semi-blind source extraction algorithm for fetal electrocardiogram based on generalized autocorrelations and reference signals , 2009 .

[24]  Piotr Podziemski,et al.  Fetal heart rate discovery: Algorithm for detection of fetal heart rate from noisy, noninvasive fetal ECG recordings , 2013, Computing in Cardiology 2013.

[25]  Salina Abdul Samad,et al.  A Review of Adaptive Line Enhancers for Noise Cancellation , 2012 .

[26]  Rik Vullings,et al.  Normal ranges for fetal electrocardiogram values for the healthy fetus of 18–24 weeks of gestation: a prospective cohort study , 2016, BMC Pregnancy and Childbirth.

[27]  Gari D Clifford,et al.  Non-invasive fetal ECG analysis , 2014, Physiological measurement.

[28]  Susana Hornillo-Mellado,et al.  Fast Technique for Noninvasive Fetal ECG Extraction , 2011, IEEE Transactions on Biomedical Engineering.

[29]  G. Camps,et al.  Fetal ECG extraction using an FIR neural network , 2001, Computers in Cardiology 2001. Vol.28 (Cat. No.01CH37287).

[30]  Olivier Sibony,et al.  Fetal electrocardiogram extraction based on non-stationary ICA and wavelet denoising , 2003, Seventh International Symposium on Signal Processing and Its Applications, 2003. Proceedings..

[31]  Janusz Jezewski,et al.  Determination of fetal heart rate from abdominal signals: evaluation of beat-to-beat accuracy in relation to the direct fetal electrocardiogram , 2012, Biomedizinische Technik. Biomedical engineering.

[32]  D. Shavit,et al.  Complete foetal ECG morphology recording by synchronised adaptive filtration , 2006, Medical and Biological Engineering and Computing.

[33]  Rik Vullings,et al.  An Adaptive Kalman Filter for ECG Signal Enhancement , 2011, IEEE Transactions on Biomedical Engineering.

[34]  Shahriar Negahdaripour,et al.  A new method for the extraction of fetal ECG from the composite abdominal signal , 2000, IEEE Transactions on Biomedical Engineering.

[35]  S. Houterman,et al.  Fetal heart rate variability during pregnancy, obtained from non‐invasive electrocardiogram recordings , 2014, Acta obstetricia et gynecologica Scandinavica.

[36]  S Cerutti,et al.  The clinical relevance of the abdominal fetal electrocardiogram. , 1986, Journal of perinatal medicine.

[37]  G. Pardi,et al.  Fetal electrocardiogram changes in relation to fetal heart rate patterns during labor. , 1974, American journal of obstetrics and gynecology.

[38]  Rubén Martín-Clemente,et al.  The Maternal Abdominal ECG as Input to MICA in the Fetal ECG Extraction Problem , 2011, IEEE Signal Processing Letters.

[39]  K. Greene,et al.  Changes in the ST waveform of the fetal lamb electrocardiogram with hypoxemia. , 1982, American journal of obstetrics and gynecology.

[40]  D A Coast,et al.  Enhancement of low-level ECG components in noise with time-sequenced adaptive filtering. , 1990, Journal of electrocardiology.

[41]  Massimo Mischi,et al.  Low-complexity R-peak detection for ambulatory fetal monitoring , 2012, Physiological measurement.

[42]  D. L. Kirk,et al.  Can fetal electrocardiography improve the prediction of intraparturn fetal acidosis? , 1986 .