Fetal ECG extraction during labor using an adaptive maternal beat subtraction technique

Abstract

Fetal ECG (FECG) monitoring using abdominal maternal signals is a non-invasive technique that allows early detection of changes in fetal wellbeing. Several other signal components have stronger energy than the FECG, the most important being maternal ECG (MECG) and, especially during labor, uterine EMG. This study proposes a new method to subtract MECG after detecting and removing abdominal signal segments with high-amplitude variations due to uterine contractions. The method removes MECG from abdominal signals using an approximation of the current MECG segment based on a linear combination of previous MECG segments aligned on the R-peak. The coefficients of the linear model are computed so that the squared error of the approximation over the whole current segment is minimized. Abdominal signal segments strongly affected by uterine contractions are detected by applying median filtering. The methods proposed are tested on real abdominal data recorded during labor, with FECG recorded using scalp electrodes synchronously recorded for comparison.

Determination of fetal heart rate from abdominal signals: evaluation of beat-to-beat accuracy in relation to the direct fetal electrocardiogram

“…The main problem of its practical implementation is the interfering maternal electrocardiogram (MECG), many times exceeding the signal of interest. A number of different approaches for the suppression of the MECG and the detection of fetal QRS complexes have been presented in the literature [18,34,36] ; however, thus far, there has been no comprehensive study evaluating the accuracy of FHR measurement in abdominal FECG signal, on a beat-to-beat basis. It should be mentioned that accuracy is a crucial issue in the interpretation of the FECG, as it directly affects the variability assessment.…”

Noninvasive Fetal Electrocardiography: An Overview of the Signal Electrophysiological Meaning, Recording Procedures, and Processing Techniques

“…In this study, three major classes have been identified, namely the ICA, 31 template subtraction, 20,36,40 and adaptive filtering, 37, 38 even though several others have been proposed in the literature. 42,43 The suitability of ICA technique for fECG extraction is not obvious considering that the purely mathematical basis of the method does not consider the several characteristics of the involved physiological signals.…”

“…36 More rarely, the template is computed from all segmented beats using particular adaptive filters. 40 Once the template has been constructed, all maternal beats are reconstructed and concatenated to estimate amECG, which is eventually subtracted from faLead. 36…”

“…The suppression of amECG from faLead occurs by correlative detraction so that the output can be considered as only fECG. 40 …”

Extract Fetal ECG from Single-Lead Abdominal ECG by De-Shape Short Time Fourier Transform and Nonlocal Median

“…On the other hand, fewer algorithms depend on the singlelead aECG signal; e.g., template subtraction (TS) [13,[23][24][25][26], and its variation based on singular value decomposition (SVD) or principal component analysis [27,28], the time-frequency analysis, like wavelet transform, pseudo-smooth Wigner-Ville distribution [29][30][31][32] (in practice, three aECG channels are averaged in [30]), and S-transform [33], sequential total variation [34], adaptive neuro-fuzzy inference system and extended Kalman filter [35], particle swarm optimization and extended Kalman smoother [36] state space reconstruction via lag map [37,38], etc. We refer the reader to, e.g., Sameni and Clifford [4] and Andreotti et al [39] for a more detailed review.…”