Head orientation and electrode placement potentially influence fetal scalp ECG waveform

Autoři: Alexandra D. J. Hulsenboom aff001;  Guy J. J. Warmerdam aff002;  Janna Weijers aff001;  Paul J. Blijham aff003;  S. Guid Oei aff001;  Judith O. E. H. van Laar aff001;  Rik Vullings aff002;  Tammo Delhaas aff004
Působiště autorů: Department of Obstetrics and Gynaecology, Máxima Medical Center, Veldhoven, the Netherlands aff001;  Faculty of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands aff002;  Department of Clinical Neurophysiology, Máxima Medical Center, Veldhoven, the Netherlands aff003;  Department of BioMedical Engineering, Maastricht University Medical Center, Maastricht, the Netherlands aff004
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article
doi: https://doi.org/10.1371/journal.pone.0223282



Fetal monitoring based on electrocardiographic (ECG) morphology is obtained from a single unipolar fetal scalp electrode. Ideally, it should be obtained from multiple leads, as ECG waveform depends on alignment between electrode and electrical heart axis. This alignment is unknown in fetuses. Besides, fetuses are surrounded by conductive media, which may influence ECG waveform. We explored the influence of electrode position and head orientation on ECG waveforms of unipolar and bipolar scalp ECGs recorded in air and in conductive medium.


We recorded ECGs in one adult subject at five different scalp positions in five different head orientations both in dry and immersed conditions. The ratio between T-amplitude and QRS-amplitude (T/QRS ratio) of unipolar and bipolar scalp ECGs was determined and compared between all conditions.


In the dry condition, we observed in the unipolar leads little to no difference between different electrode positions (maximal T/QRS difference 0.00–0.01) and minor differences between head orientations (0.02–0.03), whereas bipolar leads showed no recognizable ECG signal at all. During the immersed condition, we found variation in the unipolar leads, both between electrode positions (maximal T/QRS difference 0.02–0.05) and between head orientations (0.03–0.06). Bipolar leads showed different ECG signals in contrasting head orientations.


Both unipolar and bipolar scalp lead-derived ECG waveforms are influenced by electrode position and head orientation when the subject is submerged in a conductive medium. Fetal monitoring based on single scalp lead ECG waveform might be suboptimal, as it lacks correction for fetal head orientation and electrode position.

Klíčová slova:

Electric conductivity – Electrocardiography – Electrode potentials – Head – Scalp – Electrode recording – Fetuses


1. Greene KR, Dawes GS, Lilja H, Rosen KG. Changes in the ST waveform of the fetal lamb electrocardiogram with hypoxemia. Am J Obstet Gynecol. 1982;144(8):950–8. doi: 10.1016/0002-9378(82)90190-9 7148927

2. Rosén KG, Dagbjartsson A, Henriksson BA, Lagercrantz H, Kjellmer I. The relationship between circulating catecholamines and ST waveform in the fetal lamb electrocardiogram during hypoxia. A J Obstet Gynecol. 1984;149(2):190–5.

3. Westgate J, Harris M, Curnow JSH, Greene KR. Plymouth randomized trial of cardiotocogram only versus ST waveform plus cardiotocogram for intrapartum monitoring in 2400 cases. Am J Obstet Gynecol. 1993;169(5):1151–60. doi: 10.1016/0002-9378(93)90273-l 8238177

4. Verdurmen KMJ, Hulsenboom ADJ, van Laar JOEH, Wijn PFF, Vullings R, Oei SG. Orientation of the electrical heart axis in mid-term pregnancy. Eur J Obstet Gynecol Reprod Biol. 2016;207:243–6. doi: 10.1016/j.ejogrb.2016.10.030 27865582

5. Wilson FN, Johnston FD, Macleod AG, Barker PS. Electrocardiograms that represent the potential variations of a single electrode. Am Heart J. 1934;9(4):447–58. https://doi.org/10.1016/S0002-8703(34)90093-4%0A

6. Bolte A. Zur Ableitung und Bewertung fetaler Herzaktionspotentiale bei schwangeren Frauen. Archiv für Gynaekologie. 1961;194(6):594–610.

7. Rooijakkers MJ, Rabotti C, Oei SG, Mischi M. Low-complexity R-peak detection for ambulatory fetal monitoring. Physiol Meas. 2012;33(7):1135–50. doi: 10.1088/0967-3334/33/7/1135 22735075

8. Vullings R, Verdurmen KMJ, Hulsenboom ADJ, Scheffer S, de Lau H, Kwee A, et al. The electrical heart axis and ST events in fetal monitoring: a post-hoc analysis following a multicentre randomised controlled trial. PLoS One. 2017 Apr 14;12(4):e0175823. doi: 10.1371/journal.pone.0175823 28410419

9. Lindecrantz KG, Lilja H, Widmark C, Rosén KG. Fetal ECG during labour: a suggested standard. J Biomed Eng. 1988;10(4):351–3. https://doi.org/10.1016/0141-5425(88)90067-2 3236856

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2019 Číslo 10
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