Head orientation and electrode placement potentially influence fetal scalp ECG waveform

Alexandra D.J. Hulsenboom, Guy J.J. Warmerdam, Janna Weijers, Paul J. Blijham, S. Guid Oei, Judith O.E.H. van Laar, Rik Vullings, Tammo Delhaas (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)
71 Downloads (Pure)


Background 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. Methods 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. Results 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. Conclusions 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.

Original languageEnglish
Article numbere0223282
Number of pages9
JournalPLoS ONE
Issue number10
Publication statusPublished - 10 Oct 2019

Fingerprint Dive into the research topics of 'Head orientation and electrode placement potentially influence fetal scalp ECG waveform'. Together they form a unique fingerprint.

Cite this