Antenatal assessment using the FECG obtained via abdominal electrodes

Abstract

During the past decade a variety of intrapartum fetal monitors have been constructed that process the entire fetal electrocardiogram (FECG), obtained via a scalp electrode. They therefore differ from conventional monitors in aiming to extract relevant timing and magnitude information from the morphology of the FECG rather than simply the RR interval and hence heart rate. An intrapartum monitor such as this has been successfully developed by ourselves. This paper describes the early results obtained whilst attempting to extend this form of monitoring forward into the antenatal period. In order to achieve this the FECG must be acquired via surface electrodes placed on the maternal abdomen, which yields a signal containing the FECG amidst a number of noise sources. Our investigations into the feasibility of "antenatal abdominal FECG analysis" have been on two fronts. The first has been to produce a bedside monitor similar in function to our intrapartum device, whilst the second has been to address the possibility of performing such monitoring in ambulant subjects. At present the antenatal bedside monitor has successfully extracted and processed the FECG in approximately 75% of the cases studied, with subjects ranging from 20 weeks through to term having been monitored. We also have demonstrated the feasibility of the long term monitoring of maternal and fetal heart rate using a portable instrument.

Successful Detection of the Fetal Electrocardiogram Waveform Changes during Various States of Singletons

“…Twelve subjects were suspected to have fetal abnormalities, non-immune fetal hydrops (Cicinelli et al 1994), cardiomegaly (Cremer 1906), intrauterine fetal death (Cicinelli et al 1994), heart anomaly (Crowe et al 1996), and arrhythmia (Sato et al 2007), and they were determined by ultrasonogram, fetal heart rate monitoring or significant clinical symptoms. P, PR and QRS intervals and QTc were compared with those of normal subjects, i.e., normal ECG values.…”

“…Taylor et al (2003) in Oxford developed a new method to measure fetal ECG using a neural network method, namely blind source separation (BSS), which estimates very small signals in large noise without any prior information. This method helps a separation of fetal ECG, including P, QRS and T waves, noninvasively (Cicinelli et al 1994;Crowe et al 1996). However, the long-term measurement using the method to perceive the fetal ECG still remains difficult especially during fetal movement, including frequent changes in fetal position and presentation.…”

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

“…Suppression of the dominant component in abdominal signals -the MECG -is the decisive step in abdominal fetal electrocardiography [3,5,33,35] . The MECG amplitude of about 200 μ V is much higher than the FECG amplitude (only about 20 μ V).…”

Clinical application of magnetocardiography

“…Since then, FMCG, which provides information about fetal cardiac electrophysiology as early as the 13th week of gestation, has been considered the most reliable method for noninvasive surveillance of fetal cardiac electrophysiology, particularly during the second half of pregnancy when the presence of electrically insulating vernix caseosa impedes the recording of satisfactory fetal ECG with abdominal leads [157][158][159][160][161]. However, the latter assumption could be questionable on the light of very recent improvements in detecting the fetal ECG, not only during labor [162,163], but also with surface electrodes during pregnancy [164,165].…”