Fetal Electrocardiogram Monitoring Research Articles

Binarized spiking neural network optimized with momentum search algorithm for fetal arrhythmia detection and classification from ECG signals

Diagnosing the fetal cardiac abnormalities by fetal electrocardiogram (FECG) is a difficult task, but it is essential to identify the fetus health condition. FECG monitoring is essential to provide accurate information on the state of the fetus. Severe fetal arrhythmia can cause heart failure or death. Therefore, it must be required to identify fetal arrhythmias early. The obtained ECG signals are very noisy and have artifacts from breathing and muscle contraction, which makes ECG extraction difficult. Misdiagnosis of fetal arrhythmias can lead to inappropriate treatment, which may result in further complications. If a defect has occurred in the heart of the fetus, it leads to death. To overcome these issues, Binarized spiking neural network optimized with Momentum search algorithm for Fetal Arrhythmia Detection and Classification from ECG signals is proposed in this manuscript for classifying the output as normal and arrhythmia. Initially, the input ECG signals are considered as Fetal ECG data base. The pre-processed ECG signals are extracted by Hexadecimal Local Adaptive Binary Pattern (HLABP). These extracting features are given to BSNN classifier for categorizing the output as normal and arrhythmia. Generally, BSNN does not adopt any optimization methods to determine the optimal parameters and to guarantee an exact classification. Hence, Momentum search algorithm (MSA) is employed to enhance the weight parameters of BSNN. The proposed technique is activated in python and utilizing some performance metrics, like sensitivity, precision, recall, f-measure, specificity, accuracy compared with existing approaches.

Fetal Electrocardiogram Extraction Using Dual-Path Source Separation of Single-Channel Non-Invasive Abdominal Recordings.

The development of a method for non-invasive monitoring of fetal electrocardiogram (FECG) signals from single-channel abdominal recordings. The dual-path source separation (DPSS) architecture is introduced for the simultaneous separation of fetal and maternal ECG signals from abdominal ECG recordings. DPSS initially denoises abdominal ECG (AECG) recordings using a generative dual-path long short-term memory (DP-LSTM) network. An inception module along with a series of DP-LSTM blocks is then employed to extract the masking maps associated with fetal and maternal components. Finally, these masking maps are weighted by the AECG recording to separate maternal and fetal ECG signals. The performance of this network is evaluated on 10 pregnancies from the fetal ECG synthetic database (FECGSYNDB), 22 cases of labor and pregnancy from the abdominal and direct fetal ECG database (ADFECGDB), and 69 pregnancies from set A of non-invasive FECG challenge (NIFECGC) datasets. F1-scores of 99.03%, 97.7%, and 95.3% are reported for the detection of fetal QRS complexes in FECGSYNDB, ADFECGDB, and NIFECGC respectively. DPSS technique is also evaluated in terms of separability of fetal and maternal clusters. According to the clustering-based analyses, the average purity index of 0.9750, Jaccard index of 0.9705, and Davies-Bouldin index of 0.7429 demonstrate the high source separation capability of DPSS. The achieved performance suggests that DPSS enables accurate single-channel FECG extraction, and can replace state-of-the-art source separation techniques for this purpose. This study signifies a fundamental step towards non-invasive fetal ECG monitoring systems, which favors at-home prenatal care.

Non-Invasive Fetal Electrocardiogram Monitoring Techniques: Potential and Future Research Opportunities in Smart Textiles

During the pregnancy, fetal electrocardiogram (FECG) is deployed to analyze fetal heart rate (FHR) of the fetus to indicate the growth and health of the fetus to determine any abnormalities and prevent diseases. The fetal electrocardiogram monitoring can be carried out either invasively by placing the electrodes on the scalp of the fetus, involving the skin penetration and the risk of infection, or non-invasively by recording the fetal heart rate signal from the mother’s abdomen through a placement of electrodes deploying portable, wearable devices. Non-invasive fetal electrocardiogram (NIFECG) is an evolving technology in fetal surveillance because of the comfort to the pregnant women and being achieved remotely, specifically in the unprecedented circumstances such as pandemic or COVID-19. Textiles have been at the heart of human technological progress for thousands of years, with textile developments closely tied to key inventions that have shaped societies. The relatively recent invention of smart textiles is set to push boundaries again and has already opened the potential for garments relevant to medicine, and health monitoring. This paper aims to discuss the different technologies and methods used in non-invasive fetal electrocardiogram (NIFECG) monitoring as well as the potential and future research directions of NIFECG in the smart textiles area.

Morphology extraction of fetal electrocardiogram by slow-fast LSTM network

Fetal electrocardiogram (FECG) morphology plays an essential role in the early diagnosis of fetal health conditions. However, it is intractable to extract the clean morphology of FECG signals, which are usually contaminated by maternal ECG (MECG) and various noises. To extract the clean morphology of FECG signals from non-invasive abdominal ECG records, a high-performance and high-efficient two-stage slow-fast long short-term memory (SFLSTM) based architecture is proposed. The MECG elimination and the FECG enhancement are realized by the elaborately designed slow LSTM and fast LSTM to filter out the MECG and the residual noise components. Qualitative and quantitative experiments are conducted on the records from two public datasets. The experimental results reveal that our designed scheme achieves the best performance in kSQI, signal-to-noise ratio (SNR), and root mean square error (RMSE). The MECG elimination and the FECG enhancement improve SNR by 3.09 and 1.81 dB, respectively. The proposed fast LSTM reduces computation cost by approximately 50%, without any degradation in performance. Our method may leverage non-invasive FECG monitoring for the early detection of fetal heart diseases.

Fetal heart rate during maternal sleep.

Despite prolonged and cumulative exposure during gestation, little is known about the fetal response to maternal sleep. Eighty-four pregnant women with obesity (based on pre-pregnancy BMI) participated in laboratory-based polysomnography (PSG) with continuous fetal electrocardiogram monitoring at 36weeks gestation. Multilevel modeling revealed both correspondence and lack of it in maternal and fetal heart rate patterns. Fetal heart rate (fHR) and variability (fHRV), and maternal heart rate (mHR) and variability (mHRV), all declined during the night, with steeper rates of decline prior to 01:00. fHR declined upon maternal sleep onset but was not otherwise associated with maternal sleep stage; fHRV differed during maternal REM and NREM. There was frequent maternal waking after sleep onset (WASO) and fHRV and mHRV were elevated during these episodes. Cross-correlation analyses revealed little temporal coupling between maternal and fetal heart rate, except during WASO, suggesting that any observed associations in maternal and fetal heart rates during sleep are the result of other physiological processes. Implications of the maternal sleep context for the developing fetus are discussed, including the potential consequences of the typical sleep fragmentation that accompanies pregnancy.

Wireless ECG and cardiac monitoring systems: State of the art, available commercial devices and useful electronic components

Wireless ElectroCardioGram (ECG) systems are employed in manifold application fields: tele-monitoring, sport applications, support to ageing people at home, fetal ECG, wearable devices and ambulatory monitoring. The presence of cables often hinders user’s free movements, alongside clinicians’ routine operations. Therefore, wireless ECG systems are desirable. This paper aims at reviewing the solutions described in the literature, besides commercially available devices and electronic components useful to setup laboratory prototypes. Several systems have been developed, different in terms of the adopted technology; when approaching the development of a wireless ECG system, some important aspects should be considered: electrodes (disposable, wet/dry, without contact, insulated), analog front-end, data acquisition systems (including amplifiers, multiplexer), wireless transmission technology (e.g. WiFi, Bluetooth) and power consumption (battery lifetime, miniaturization purposes). Technological advancements and continuous research have already brought to miniaturized and comfortable devices, but there is still room for improvement on multiple sides.

A study of a fetal heart rate calculation system based on R-R interval.

BACKGROUND: Fetal electrocardiogram (FECG) can be obtained in a non-invasive manner to monitor fetal growth status.OBJECTIVE: In this study, a fetal heart rate (FHR) calculation system was proposed, which consists of the FECG recorder (MF-HOLTER) and the FECG monitoring software (FECG-MS). The abdomen electrocardiogram (AECG) of pregnant woman is acquired through the MF-HOLTER. The FECG-MS packs the AECG data and calls the FECG separation algorithm to obtain the separated FECG and the fetal QRS (FQRS) position. The FHR is further obtained by calculating the R-R interval value. At the same time, this study proposed a FQRS position correction algorithm to calculate the correct FHR values.METHOD: In order to verify the accuracy of the FHR calculation, the ECG signal of FLUKE’s PS320 FETAL SIMULATOR and clinical data were simultaneously tested.RESULTS: The accuracy rate is over 98% in processing the simulator’s data. In processing clinical data, the FHR values obtained by both the system proposed in this study and Monica AN24 are very close, and the difference is less than 1 bpm.CONCLUSION: The results show that the FHR calculation system is accurate and stable, and has a positive application value and prospect.

Investigation of Methods to Extract Fetal Electrocardiogram from the Mother's Abdominal Signal in Practical Scenarios.

Monitoring of fetal electrocardiogram (fECG) would provide useful information about fetal wellbeing as well as any abnormal development during pregnancy. Recent advances in flexible electronics and wearable technologies have enabled compact devices to acquire personal physiological signals in the home setting, including those of expectant mothers. However, the high noise level in the daily life renders long-entrenched challenges to extract fECG from the combined fetal/maternal ECG signal recorded in the abdominal area of the mother. Thus, an efficient fECG extraction scheme is a dire need. In this work, we intensively explored various extraction algorithms, including template subtraction (TS), independent component analysis (ICA), and extended Kalman filter (EKF) using the data from the PhysioNet 2013 Challenge. Furthermore, the modified data with Gaussian and motion noise added, mimicking a practical scenario, were utilized to examine the performance of algorithms. Finally, we combined different algorithms together, yielding promising results, with the best performance in the F1 score of 92.61% achieved by an algorithm combining ICA and TS. With the data modified by adding different types of noise, the combination of ICA-TS-ICA showed the highest F1 score of 85.4%. It should be noted that these combined approaches required higher computational complexity, including execution time and allocated memory compared with other methods. Owing to comprehensive examination through various evaluation metrics in different extraction algorithms, this study provides insights into the implementation and operation of state-of-the-art fetal and maternal monitoring systems in the era of mobile health.

Evaluation of an external fetal electrocardiogram monitoring system: a randomized controlled trial

The objective of the study was to compare interpretability of 2 intrapartum abdominal fetal heart rate-monitoring strategies. We hypothesized that an external fetal electrocardiography monitoring system, a newer technology using wireless abdominal pads, would generate more interpretable fetal heart rate data compared with standard external Doppler fetal heart rate monitoring (standard external monitoring). We conducted a randomized controlled trial at 4 Utah hospitals. Patients were enrolled at labor admission and randomized in blocks based on body mass index to fetal electrocardiography or standard external monitoring. Two reviewers, blinded to study allocation, reviewed each fetal heart rate tracing. The primary outcome was the percentage of interpretable minutes of fetal heart rate tracing. An interpretable minute was defined as >25% fetal heart rate data present and no more than 25% continuous missing fetal heart rate data or artifact present. Secondary outcomes included the percentage of interpretable minutes of fetal heart rate tracing obtained while on study device only, the number of device adjustments required intrapartum, clinical outcomes, and patient/provider device satisfaction. We determined that 100 patients per arm (200 total) would be needed to detect a 5% difference in interpretability with 95% power. A total of 218 women were randomized, 108 to fetal electrocardiography and 110 to standard external monitoring. Device setup failure occurred more often in the fetal electrocardiography group (7.5% [8 of 107] vs 0% [0 of 109] for standard external monitoring). There were no differences in the percentage of interpretable tracing between the 2 groups. However, fetal electrocardiography produced more interpretable fetal heart rate tracing in subjects with a body mass index ≥30 kg/m2. When considering the percentage of interpretable minutes of fetal heart rate tracing while on study device only, fetal electrocardiography outperformed standard external monitoring for all subjects, regardless of maternal body mass index. Maternal demographics and clinical outcomes were similar between arms. In the fetal electrocardiography group, more device changes occurred compared with standard external monitoring (51% vs 39%), but there were fewer nursing device adjustments (2.9 vs 6.2 mean adjustments intrapartum, P < .01). There were no differences in physician device satisfaction scores between groups, but fetal electrocardiography generated higher patient satisfaction scores. Fetal electrocardiography performed similarly to standard external monitoring when considering percentage of interpretable tracing generated in labor. Furthermore, patients reported overall greater satisfaction with fetal electrocardiography in labor. Fetal electrocardiography may be particularly useful in patients with a body mass index ≥30 kg/m2.

Evaluating the reliability of fetal electrocardiogram monitoring that acts via the abdominal wall of pregnant rabbits

Evaluating the reliability of fetal electrocardiogram monitoring that acts via the abdominal wall of pregnant rabbits

Computer-based intrapartum fetal monitoring and beyond: A review of the 2nd Workshop on Signal Processing and Monitoring in Labor (October 2017, Oxford, UK).

The second Signal Processing and Monitoring in Labor workshop gathered researchers who utilize promising new research strategies and initiatives to tackle the challenges of intrapartum fetal monitoring. The workshop included a series of lectures and discussions focusing on: new algorithms and techniques for cardiotocogoraphy (CTG) and electrocardiogram acquisition and analyses; the results of a CTG evaluation challenge comparing state-of-the-art computerized methods and visual interpretation for the detection of arterial cord pH<7.05 at birth; the lack of consensus about the role of intrapartum acidemia in the etiology of fetal brain injury; the differences between methods for CTG analysis "mimicking" expert clinicians and those derived from "data-driven" analyses; a critical review of the results from two randomized controlled trials testing the former in clinical practice; and relevant insights from modern physiology-based studies. We concluded that the automated algorithms performed comparably to each other and to clinical assessment of the CTG. However, the sensitivity and specificity urgently need to be improved (both computerized and visual assessment). Data-driven CTG evaluation requires further work with large multicenter datasets based on well-defined labor outcomes. And before first tests in the clinic, there are important lessons to be learnt from clinical trials that tested automated algorithms mimicking expert CTG interpretation. In addition, transabdominal fetal electrocardiogram monitoring provides reliable CTG traces and variability estimates; and fetal electrocardiogram waveform analysis is subject to promising new research. There is a clear need for close collaboration between computing and clinical experts. We believe that progress will be possible with multidisciplinary collaborative research.

Home-based mobile fetal/maternal electrocardiogram acquisition and extraction with cloud assistance.

Electrocardiogram (ECG) monitoring of the fetus during pregnancy, before and during labor, can provide crucial information for the assessment of fetal well-being and development, as well as labor progress. An out-of-clinics fetal ECG monitoring system may pave the way for instant diagnosis, suggesting immediate intervention, which could help reduce the fetal mortality rate. In this paper, we present an unobtrusive fetal maternal ECG monitoring system which can operate in the home setting. The acquisition of the mother's abdominal ECG is done using the non-contact electrode approach. The extraction of the fetal ECG from the combined fetal/maternal ECG signal is investigated using both Fast Independent Component Analysis (FastICA) and RobustICA algorithms. An accelerometer is integrated for motion artifact detection which would help reduce interferences due to movement. The device also is connected to a cloud server, allowing doctors to access the data in real time.

A Fetal ECG Monitoring System Based on the Android Smartphone.

In this paper, a fetal electrocardiogram (ECG) monitoring system based on the Android smartphone was proposed. We designed a portable low-power fetal ECG collector, which collected maternal abdominal ECG signals in real time. The ECG data were sent to a smartphone client via Bluetooth. Smartphone app software was developed based on the Android system. The app integrated the fast fixed-point algorithm for independent component analysis (FastICA) and the sample entropy algorithm, for the sake of real-time extraction of fetal ECG signals from the maternal abdominal ECG signals. The fetal heart rate was computed using the extracted fetal ECG signals. Experimental results showed that the FastICA algorithm can extract a clear fetal ECG, and the sample entropy can correctly determine the channel where the fetal ECG is located. The proposed fetal ECG monitoring system may be feasible for non-invasive, real-time monitoring of fetal ECGs.

Women's experience of wearing a portable fetal-electrocardiogram device to monitor small-for-gestational age fetus in their home environment.

Objective:To determine the acceptability, to women, of wearing a portable fetal electrocardiogram recording device at different stages of pregnancy and to gain insight into their experience of its use for long-periods of monitoring of small-for-gestational fetuses in the home environment.Methods:A qualitative study using both a questionnaire and focus group involving women with singleton pregnancy >24 weeks gestation, no evidence of fetal malformation and an estimated fetal weight below 10th gestational centile on ultrasound scan. Fetal heart rate recordings were collected for up to 20 h.Results:In total, 59 questionnaires were completed; 35 after wearing the monitor for the first time and an additional 24 from the women who wore the device for a second time. Six women participated in the focus group; the principal theme identified related to the practicality of the fetal electrocardiogram device. Other themes identified were the discomfort that resulted from wearing the monitor and the reassurance provided in knowing that the baby’s heart rate was being monitored.Conclusion:Long-term ambulatory fetal electrocardiogram monitoring is an acceptable method of monitoring small-for-gestational fetuses. Overall, women concluded that benefits of wearing the device outweighed any discomfort it caused.

Fetal Non-invasive Electrocardiography Contributes to Better Diagnostics of Fetal Distress: A Cross-sectional Study Among Patients with Pre-eclampsia

Fetal distress is a result of acute or chronic disturbances in the system of "mother-placenta-fetus" in pre-eclampsia (PE). The aim of the investigation was to compare the accuracy of antenatal fetal distress diagnostics in cases of traditional cardiotocography (CTG) waveform evaluation and analysis of morphological non-invasive electrocardiogram (ECG) parameters in anterpartum patients with PE. Fetal non-invasive ECG antenatal recordings of 122 pregnant patients at 34 to 40 weeks of gestation were examined. In Group I, there were 32 women with physiological gestation and normal fetal condition according to haemodynamic Doppler values. Group II involved 48 patients with mild and moderate PE whom were performed Doppler investigation. In Group III, 42 patients with severe PE were monitored with haemodynamic Doppler. Fetal autonomic tone was lower with the relative increase of low frequency (LF) branch in the patients of pre-eclamptic group. The increased value of the amplitude of mode (AMo) and stress index (SI) was associated with adrenergic overactivity. It has induced pQ and QT shortening, increased T/QRS ratio and decelerations appearance. The rate of antenatal fetal distress retrospectively was 31.1 % in PE. The traditional analysis of CTG parameters has showed sensitivity (72.7%) and specificity (87.1%). In addition to the conventional CTG analysis, evaluation of ECG parameters has contributed to better diagnostics of fetal distress. Sensitivity and specificity of non-invasive fetal ECG were absolutely equal in this study (100%). The results suggest that fetal non-invasive ECG monitoring is more objective than conventional CTG.

A multi-step method with signal quality assessment and fine-tuning procedure to locate maternal and fetal QRS complexes from abdominal ECG recordings

Non-invasive monitoring of fetal electrocardiogram (fECG) plays an important role in detecting and diagnosing fetal diseases. This study aimed to develop a multi-step method for locating both maternal and fetal QRS complexes from abdominal ECG (aECG) recordings. The proposed method included four major steps: abdominal ECG pre-processing, maternal QRS complex locating, maternal ECG cancellation and fetal QRS complex locating. Signal quality assessment (SQA) and fine-tuning for maternal ECG (FTM) were implemented in the first and third steps, respectively. The method was then evaluated using 75 non-invasive 4-channel aECG recordings provided by the PhysioNet/Computing in Cardiology Challenge 2013. The F1 measure, which is a new index introduced by Behar et al ( Proc. Comput. Cardiol. 40 297–300), was used to assess the locating accuracy. The other two indices, mean squared error of heart rate (MSE_HR) between the fetal HR signals estimated from the reference and our method (MSE_HR in bpm2) and root mean squared difference between the corresponding fetal RR intervals (MSE_RR in ms) were also used to assess the locating accuracy. Overall, for the maternal QRS complex, the F1 measure was 98.4% from the method without the implementation of SQA, and it was improved to 99.8% with SQA. For the fetal QRS complex, the F1 measure, MSE_HR and MSE_RR were 84.9%, 185.6 bpm2 and 19.4 ms for the method without both SQA and FTM procedures. They were improved to 93.9%, 47.5 bpm2 and 7.6 ms with both SQA and FTM procedures. These improvements were observed from each individual subject. It can be concluded that implementing both SQA and FTM procedures could achieve better performance for locating both maternal and fetal QRS complexes.

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

Accurate assessment of fetal well-being is one of the most important tasks for obstetricians. It is still difficult to measure fetal electrocardiogram (ECG) during fetal movements. Recently, a new method, blind source separation with reference signals, was proposed for stable measurements. This method distinguishes weak signals from noisy mixed signals with little information about the sources. The aim of this study is to estimate the ability of this method for fetal ECG monitoring and to establish standard fetal ECG electrocardiogram values of normal singletons including during fetal movement. The subjects enrolled were 167 pregnant women with normal single pregnancy from 18- to 41-week gestation, who regularly visited Tohoku University Hospital, and 12 pregnant women with fetal abnormality. Fetal signals were successfully separated in 163 of 179 subjects at 91.1% success rate regardless of fetal movements. Time intervals of ECG (P, PR and QRS intervals and QTc) were measured. The standard curves of each interval through the gestational period were obtained. The data in active phase were compared to that in rest phase and the data obtained from normal and abnormal fetuses were investigated. PR intervals in the rest phase were prolonged compared to those in the active phase. Fetal ECG showed anomalous values such as PR interval or QTc prolongation in the abnormal fetuses. The fetal ECG was measured by the new method with or without fetal movements, and the standard fetal ECG values have been established. This study provides a foundation for further detailed clinical studies.

Clinical assessment of fetal electrocardiogram monitoring in labor

Clinical assessment of fetal electrocardiogram monitoring in labor

Clinical assessment of fetal electrocardiogram monitoring in labour.

To assess the potential clinical value of fetal electrocardiographic (ECG) monitoring in labour. Descriptive study of the use of ECG waveform analysis during labour and its correlation with other indices of fetal and neonatal well-being. Teaching hospital in Oxford. 86 high risk pregnancies. Suitability of ST Segment Analyser (Cinventa, Sweden) for clinical use; relation between the T/QRS ratio during labour (an index of ST segment and T wave elevation) and intrapartum cardiotocography, umbilical artery pH at birth and Apgar scores; T/QRS ratio trends in labour. The system was robust and user-friendly. No statistically significant relation was found between T/QRS ratios in labour and FHR abnormalities in the cardiotocograph. There was a weak relation between T/QRS ratios and umbilical artery acidosis: at a cervical dilatation of 4 cm, the Spearman rank correlation of the mean T/QRS ratio with umbilical artery actual base deficit was r = -0.31, 0.05 greater than P greater than 0.01. The correlation of T/QRS with the umbilical artery pH was not statistically significant, although a trend was present (Spearman rank: r = -0.26, P greater than 0.05). Correlation of the T/QRS ratio with Apgar scores at 1 and at 5 min was not statistically significant. Only 3 of 16 infants with an Apgar score of less than 7 at 1 min had a mean T/QRS ratio above 0.25 at any time during labour. Further research is necessary before a decision can be made whether this new method of fetal monitoring should be introduced into clinical practice.

Changes in the conduction of the fetal electrocardiogram to the maternal abdominal surface during gestation

A technique for recording high-quality vectorcardiograms from the fetus in utero is described. A study was conducted to clarify conflicting views on the mechanism of fetal electrocardiogram (FECG) signal transmission to the maternal abdominal surface during the latter half of gestation. The results of this study support the view that a general pattern of uniform conduction of FECG currents exists between 20 and 28 weeks' gestation in most subjects, that signal magnitudes decrease markedly between 28 and 34 weeks' gestation and conduction tends to behave as if it is nonuniform through the maternal abdominal volume, and that a preferred signal pathway, possibly through the oronasal cavities of the fetus, appears to develop after 34 weeks gestation and continues until term. Two different abdominal FECG lead systems are recommended on the basis of these findings which should maximize the accuracy of FECG monitoring of the preterm fetus.