Comparison of SVD methods to extract the foetal electrocardiogram from cutaneous electrode signals

Abstract

The paper presents and compares three methods making use of the singular value decomposition (SVD) of a matrix to extract the foetal electrocardiogram (FECG) from cutaneously recorded electrode signals. The first method constructs a set of orthogonal foetal signals (the so-called principal foetal signals) from the recordings, but needs electrode positions far from the foetal heart, in addition to the abdominal electrodes that pick up a mixture of maternal and foetal electrocardiogram. An online adaptive algorithm has been developed such that a real-time implementation becomes feasible. The second method is a new online approach to a technique presented by van Oosterom. Although this method has some important drawbacks and is suboptimal as far as foetal signal-to-noise ratio is concerned, it is still very useful when only a foetal trigger is required, as the signal obtained is not a complete FECG. Finally, a third method is proposed, based on the generalised SVD and interpreted with the new concept of oriented signal-to-signal ratio. An online version is also presented for this method and some results are shown.

ICA-Based Fetal Monitoring

“…This approach (and its variants) has been conveniently addressed in several papers (see e.g. Callaerts et al (1990);De Lathauwer et al (2000b); Kanjilal et al (1997)). We shall try to focus on the most relevant aspects: consider that we are given q samples v(1),...,v(q) of the vector signal v(t).…”

“…The complete procedure can be accomplished in real time with low computational cost. In any case, the performance of the whitening-based approaches is strongly dependent on the position of the electrodes (Callaerts et al, 1990), which usually becomes a matter of trial and error.…”

A real-time intrauterine catheter technique for fetal electrocardiogram monitoring

“…However, obtaining a FECG from the abdominal wall is non-trivial. The FECG signal strength is very weak, and corrupted with interfering noise from the maternal electrocardiogram (ECG) and muscle activity of the abdominal surface [1][2].…”

“…However, obtaining a FECG from the abdominal wall is non-trivial. The FECG signal strength is very weak, and corrupted with interfering noise from the maternal electrocardiogram (ECG) and muscle activity of the abdominal surface [1][2].Since the IC technique is non-invasive to the fetus but invasive to the mother, the catheter makes a nice compromise between the non-invasive abdominal wall and scalp electrode techniques. Since the catheter is placed in close proximity to the fetus and even touches the fetus in some places, the adjacency allows for a greater chance of obtained a FECG with a favorable signal-to-noise ratio.…”

“…These methods include non-invasive and invasive techniques. The non-invasive methods can further be divided into noninvasive to the mother and fetus which include the abdominal wall approaches, and non-invasive to the fetus which includes the intrauterine catheter (IC) procedure [1][2][3][4]. The clinically accepted scalp electrode is categorized as an invasive method since the electrode is invasive to the mother and fetus [5].…”