Evaluation of standardized, computerized Dawes/Redman heart-rate analysis based on different recording methods and in relation to fetal beat-to-beat heart rate variability

Correlation of short-term variation derived from novel ambulatory fetal electrocardiography monitor with computerized cardiotocography

OBJECTIVES

To compare short-term variation (STV) outputs from a novel self-applied non-invasive fetal electrocardiography (NIFECG) device with those obtained on computerized cardiotocography (cCTG). Technological and algorithmic limitations and mitigation strategies were also evaluated.

METHODS

This was a prospective cohort study of women with a singleton pregnancy over 28 + 0 weeks' gestation attending a tertiary London hospital for cCTG assessment between June 2021 and June 2022. Women underwent concurrent monitoring with both NIFECG and cCTG for up to 1 h. Postprocessing of NIFECG data using various filtering methods produced NIFECG-STV (eSTV) values, which were compared with cCTG-STV (cSTV) outputs. Linear correlation, mean bias, precision and limits of agreement were assessed for STV derived by the different methods of computation and mathematical correction.

RESULTS

Overall, 306 concurrent NIFECG and cCTG traces were collected from 285 women. Fully filtered eSTV was correlated very strongly with cSTV (r = 0.911, P < 0.001), but generated results only in 142/306 (46.4%) 1-h traces owing to the removal of traces with lower-quality signals. Partial filtering generated more eSTV data (98.4%), but with a weak correlation with cSTV (r = 0.337, P < 0.001). The difference in STV between the monitors (eSTV - cSTV) increased with signal loss; in traces with > 60% signal loss, the values became highly discrepant. Removal of traces with > 60% signal loss resulted in a stronger correlation with cSTV, while still generating eSTV results for 65% of traces. Correcting these remaining eSTV values for signal loss using linear regression analysis further improved correlation with cSTV (r = 0.839, P < 0.001).

CONCLUSIONS

The discrepancy between STV computed by NIFECG and cCTG necessitates signal filtering, exclusion of poor-quality traces and eSTV correction. This study demonstrates that, with such correction, NIFECG is able to produce STV values that are strongly correlated with those of cCTG. This evidence base for NIFECG monitoring and interpretation is a promising step forward in the development of safe and effective at-home fetal heart-rate monitoring. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Can fetal heart rate variability obtained from cardiotocography provide the same diagnostic value like from electrophysiological interbeat intervals?

OBJECTIVE

Fetal heart rate variability (HRV) is widely used for monitoring fetal developmental disturbances. Only expensive fetal magnetocardiography (fMCG) allows the precise recording of the individual fetal heart beat intervals uncovering also highly frequent vagal modulation. In contrast, transabdominal fetal electrocardiography (fECG) suffers from noise overlaying the fetal cardiac signal. Cardiotocography (CTG) is the clinical method of choice, however, based on Doppler ultrasound, improper to resolve single beats concisely. The present work addresses the transferability of established electrophysiological HRV indices to CTG recordings during the fetal maturation period of 20-40 weeks of gestation (WGA).

APPROACH

We compared (a) HRV indices obtained from fMCG, CTG and fECG of short-term amplitude fluctuations (sAMPs) and long-term amplitude fluctuations (lAMPs) and complexity, and (b) their diagnostic value for identifying maturational age, fetal growth restriction (FGR) and small for gestational age (SGA). We used the functional brain age score (fABAS) and categories of long- and short-term regulation and complexity.

MAIN RESULTS

Integrating all substudies, we found: (a) indices related to long-term regulation, and with modified meaning and values of short-term regulation and sympathovagal balance (SVB) according to electrophysiological HRV standards can be obtained from CTG. (b) Models using HRV indices calculated from CTG allow the identification of maturational age and discriminate FGR from controls with almost similar precision as electrophysiological means. (c) A modified set of HRV parameters containing short- and long-term regulation and long-term/short-term ratio appeared to be most suitable to describe autonomic developmental state when CTG data is used.

SIGNIFICANCE

Whereas the predominantly vagally modulated beat-to-beat precise high frequencies of HRV are not assessable from CTG, we identified relevant related HRV indices and categories for CTG recordings with diagnostic potential. They require further evaluation and confirmation with respect to any issues of fetal developmental and perinatal problems in subsequent studies. This methodology significantly extends the measures of established CTG devices. Novelty and significance HRV indices provide predestinated diagnostic markers of autonomic control in fetuses. However, the established CTG does not provide the temporal precision of electrophysiological recordings. Beat-to-beat related, mainly vagally modulated behavior is not exactly represented in CTG. However, a set of CTG-specific HRV indices that are mainly comparable to established electrophysiological HRV parameters obtained by magnetocardiography or electrocardiography provided almost similar predictive value for fetal maturational age and were helpful in characterizing FGR. These results require validation in the monitoring of further fetal developmental disturbances. We recommend a corresponding extension of CTG methodology.

Maternal Serotonin Reuptake Inhibitor Antidepressants Have Acute Effects on Fetal Heart Rate Variability in Late Gestation

Background: Prenatal exposure to serotonin reuptake inhibitor (SRI) antidepressants increases risk for adverse neurodevelopmental outcomes, yet little is known about whether effects are present before birth. In relation to maternal SRI pharmacokinetics, this study investigated chronic and acute effects of prenatal SRI exposure on third-trimester fetal heart rate variability (HRV), while evaluating confounding effects of maternal depressed mood. Methods: At 36-weeks' gestation, cardiotocograph measures of fetal HR and HRV were obtained from 148 pregnant women [four groups: SRI-Depressed (n = 31), SRI-Non-Depressed (n = 18), Depressed (unmedicated; n = 42), and Control (n = 57)] before, and ~5-h after, typical SRI dose. Maternal plasma drug concentrations were quantified at baseline (pre-dose) and four time-points post-dose. Mixed effects modeling investigated group differences between baseline/pre-dose and post-dose fetal HR outcomes. Post hoc analyses investigated sex differences and dose-dependent SRI effects. Results: Maternal SRI plasma concentrations were lowest during the baseline/pre-dose fetal assessment (trough) and increased to a peak at the post-dose assessment; concentration-time curves varied widely between individuals. No group differences in fetal HR or HRV were observed at baseline/pre-dose; however, following maternal SRI dose, short-term HRV decreased in both SRI-exposed fetal groups. In the SRI-Depressed group, these post-dose decreases were displayed by male fetuses, but not females. Further, episodes of high HRV decreased post-dose relative to baseline, but only among SRI-Non-Depressed group fetuses. Higher maternal SRI doses also predicted a greater number of fetal HR decelerations. Fetuses exposed to unmedicated maternal depressed mood did not differ from Controls. Conclusions: Prenatal SRI exposure had acute post-dose effects on fetal HRV in late gestation, which differed depending on maternal mood response to SRI pharmacotherapy. Importantly, fetal SRI effects were sex-specific among mothers with persistent depressive symptoms, as only male fetuses displayed acute HRV decreases. At trough (pre-dose), chronic fetal SRI effects were not identified; however, concurrent changes in maternal SRI plasma levels suggest that fetal drug exposure is inconsistent. Acute SRI-related changes in fetal HRV may reflect a pharmacologic mechanism, a transient impairment in autonomic functioning, or an early adaption to altered serotonergic signaling, which may differ between males and females. Replication is needed to determine significance with postnatal development.

Antenatal cardiotocography with and without computer analysis in high-risk pregnancy: a randomized clinical trial

BACKGROUND

Cardiotocography or nonstress test is a technical means of recording the fetal heartbeat and uterine contractions for antenatal monitoring.

OBJECTIVE

This study aimed to evaluate whether antepartum cardiotocography with computer analysis (computerized cardiotocography) increases the incidence of cesarean delivery in women with high-risk pregnancies but without intrauterine growth restriction.

STUDY DESIGN

This was a parallel group nonblinded randomized clinical trial of singletons with high-risk pregnancies admitted for inpatient monitoring between 24 0/7 and 37 6/7 weeks' gestation. Eligible participants were randomly allocated in a 1:1 ratio to antenatal monitoring with either standard cardiotocography or computerized cardiotocography. Women randomized to the computerized cardiotocography arm received cardiotocographic monitoring with computerized analysis in a central monitoring station. The primary outcome was the incidence of cesarean delivery.

RESULTS

Overall, 28 women were enrolled in this trial. In addition, 14 women were randomized to the computerized cardiotocography group and 14 women to the control group. No woman was excluded after randomization or lost to follow-up. Cesarean delivery occurred in 9 women (64.3%) in the computerized cardiotocography group and 9 women (64.3%) in the control group (relative risk, 1.00; 95% confidence interval, 0.21-4.69).There was no significant between-group difference in preterm birth, gestational age at delivery, Apgar score, and birthweight.

CONCLUSION

Among women with high-risk pregnancies, use of computerized cardiotocography for antenatal monitoring did not result in a significant increase in cesarean delivery compared with standard cardiotocography. The results of this single-center randomized trial require confirmation in multicenter studies.

A feasibility study on non-invasive fetal ECG to evaluate prenatal autonomic nervous system activity

BACKGROUND

Maturity of the autonomic nervous system (ANS) is of paramount importance for fetal adaptation to extrauterine life and for early neurological development. Markers of ANS maturity, such as electrophysiological heart rate parameters, are of interest as tools to determine prenatal fetal maturity. The available technology, fetal magnetocardiography is expensive and not suitable for clinical use. Detection of fetal electrocardiographic signals using traditional ECG leads on the maternal abdomen may be brought to the bedside, but is technically challenging. Our group has recently developed an innovative system consisting of a standard ECG with external leads applied on the maternal abdomen coupled with a software that extracts the fetal heart signal from the maternal noise.

OBJECTIVE

To validate the use of this innovative non-invasive system to detect fetal ECG (fECG) and its ability to detect changes in electrophysiological fetal cardiac parameters associated with ANS maturation.

STUDY DESIGN

we recruited 50 pregnant women between 24 and 41 weeks and they received non-invasive recording of fECG.

RESULTS

fECG was measurable at all gestational ages. Fetal heart rate variability (RR interval) and other associated parameters, such as low and high frequency increased with gestational age, particularly up to the 31st week.

CONCLUSIONS

This study shows that non-invasive fECG is feasible throughout a broad range of gestational ages and allows detecting electrophysiological parameters of the fetal heart that may be used a surrogate of ANS maturity. Technological implementation of this system and its further exploitation may generate new tool to estimate fetal maturity.

Relative accuracy of computerized intrapartum fetal heart rate pattern recognition by ultrasound and abdominal electrocardiogram detection

INTRODUCTION

Noninvasive fetal heart rate monitoring using transabdominal fetal electrocardiographic detection is now commercially available and has been demonstrated to be an effective alternative to traditional Doppler ultrasonographic techniques. Our objective in this study was to compare the results of computerized identification of fetal heart rate patterns generated by ultrasound-based and transabdominal fetal electrocardiogram-based techniques with simultaneously obtained fetal scalp electrode-derived heart rate information.

MATERIAL AND METHODS

We applied an objective computer-based analysis for recognition of fetal heart rate patterns (Monica Decision Support) to data obtained simultaneously from a direct fetal scalp electrode, Doppler ultrasound, and the abdominal-fetal electrocardiogram techniques. This allowed us to compare over 145 hours of fetal heart rate patterns generated by the external devices with those derived from the scalp electrode in 30 term singleton uncomplicated pregnancies during labor. The direct fetal scalp electrode is considered to be the most accurate and reliable technique used in current clinical practice, and was, therefore, used as the standard for comparison. The program quantified the baseline heart rate, long- and short-term variability. It indicated when an acceleration or deceleration was present and whether it was large or small.

RESULTS

Ultrasound was associated with significantly greater deviations from the fetal scalp electrode results than the abdominal fetal electrocardiogram technique in recognizing the correct baseline heart rate, its variability, and the presence of small and large accelerations and small decelerations. For large decelerations the two external methods were each not significantly different from the scalp electrode results.

CONCLUSIONS

Noninvasive fetal heart rate monitoring using maternal abdominal wall electrodes to detect fetal cardiac activity more reliably reproduced the computerized analysis of heart rate patterns derived from a direct fetal scalp electrode than did traditional ultrasound-based monitoring. Abdominal-fetal electrocardiogram should, therefore, be considered a primary option for externally monitored patients.

A systematic review on the utility of non-invasive electrophysiological assessment in evaluating for intra uterine growth restriction

Background

Non-invasive electrophysiological assessment (NIEA) is an evolving area in fetal surveillance and is attracting increasing research interest. There is however, limited data outlining its utility in evaluating intra uterine growth restriction (IUGR). The objective of this study was to carry out a systematic review to outline the utility of NIEA parameters in evaluating IUGR.

Methods

A systematic review of peer reviewed literature was performed, searching PUBMED, Ovid MEDLINE and EMBASE. The outcomes of interest included NIEA parameters [P wave duration, PR interval, QRS duration, QT interval, T/QRS ratio, short term variability (STV) and long term variability (LTV)] and a descriptive summary of relevant studies as well.

Results

Sixteen studies were identified as suitable for inclusion. The utility of NIEA parameters were investigated in tabular form. In particular, QRS and QT duration, T/QRS ratio, STV and PRSA analysis displayed utility and merit further consideration in evaluating for IUGR. Issues identified in the review were in relation to variances in definition of IUGR, small sample sizes and the lack of technological consistency across studies.

Conclusion

NIEA shows promise as an adjunct surveillance tool in fetal diagnostics for IUGR. Larger prospective studies should be directed towards establishing reliable parameters with a focus on uniformity of IUGR definition, technological consistency and the individualisation of NIEA parameters.

Electronic supplementary material

The online version of this article (10.1186/s12884-019-2357-9) contains supplementary material, which is available to authorized users.

An antenatal marker of neurodevelopmental outcomes in infants with congenital heart disease

OBJECTIVE

Prenatal exposures are known to alter fetal neurodevelopment and autonomic control. We aimed to explore the correlation between fetal autonomic activity, measured by fetal heart rate variability, and 18-month developmental outcome in subjects with congenital heart disease.

STUDY DESIGN

From 2010 to 2013, 5 fetuses with hypoplastic left heart syndrome, 9 with transposition of the great arteries and 9 with tetralogy of Fallot were included in this prospective cohort study. A maternal abdominal fetal electrocardiogram monitor recorded fetal heart rate at 34 to 38 weeks gestational age. We assessed associations between fetal heart rate parameters including interquartile range and s.d. of the fetal RR intervals and 18-month Bayley Scales of Infant Development-III scores using Pearson's correlation coefficient. Multivariable regression modeling identified predictors of neurodevelopmental scores.

RESULTS

Fetal heart rate variability parameters at 34 to 38 weeks gestational age correlated with 18-month Cognition (r=0.47, P=0.03) and Motor scores (r=0.66, P=0.001). The interquartile range of the fetal RR intervals predicted Cognition (β=0.462, P=0.028, R2=0.282) and Motor (β=0.637, P<0.001, R2=0.542) scores.

CONCLUSIONS

In fetuses with congenital heart disease, low heart rate variability at 34 to 38 weeks gestational age predicts diminished 18-month Cognitive and Motor performance. Prenatal autonomic activity may serve as a marker of early childhood development in these high-risk patients.

Monitoring fetal maturation-objectives, techniques and indices of autonomic function

Monitoring the fetal behavior does not only have implications for acute care but also for identifying developmental disturbances that burden the entire later life. The concept, of 'fetal programming', also known as 'developmental origins of adult disease hypothesis', e.g. applies for cardiovascular, metabolic, hyperkinetic, cognitive disorders. Since the autonomic nervous system is involved in all of those systems, cardiac autonomic control may provide relevant functional diagnostic and prognostic information. The fetal heart rate patterns (HRP) are one of the few functional signals in the prenatal period that relate to autonomic control and, therefore, is predestinated for its evaluation. The development of sensitive markers of fetal maturation and its disturbances requires the consideration of physiological fundamentals, recording technology and HRP parameters of autonomic control. Based on the ESGCO2016 special session on monitoring the fetal maturation we herein report the most recent results on: (i) functional fetal autonomic brain age score (fABAS), Recurrence Quantitative Analysis and Binary Symbolic Dynamics of complex HRP resolve specific maturation periods, (ii) magnetocardiography (MCG) based fABAS was validated for cardiotocography (CTG), (iii) 30 min recordings are sufficient for obtaining episodes of high variability, important for intrauterine growth restriction (IUGR) detection in handheld Doppler, (iv) novel parameters from PRSA to identify Intra IUGR fetuses, (v) evaluation of fetal electrocardiographic (ECG) recordings, (vi) correlation between maternal and fetal HRV is disturbed in pre-eclampsia. The reported novel developments significantly extend the possibilities for the established CTG methodology. Novel HRP indices improve the accuracy of assessment due to their more appropriate consideration of complex autonomic processes across the recording technologies (CTG, handheld Doppler, MCG, ECG). The ultimate objective is their dissemination into routine practice and studies of fetal developmental disturbances with implications for programming of adult diseases.