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Shen J, Liu Y, Zhang M, Pumir A, Mu L, Li B, Xu J. Multi-channel electrohysterography enabled uterine contraction characterization and its effect in delivery assessment. Comput Biol Med 2023; 167:107697. [PMID: 37976821 DOI: 10.1016/j.compbiomed.2023.107697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 11/03/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
Uterine contractions are routinely monitored by tocodynamometer (TOCO) at late stage of pregnancy to predict the onset of labor. However, TOCO reveals no information on the synchrony and coherence of contractions, which are important contributors to a successful delivery. The electrohysterography (EHG) is a recording of the electrical activities that trigger the local muscles to contract. The spatial-temporal information embedded in multiple channel EHG signals make them ideal for characterizing the synchrony and coherence of uterine contraction. To proceed, contractile time-windows are identified from TOCO signals and are then used to segment out the simultaneously recorded EHG signals of different channels. We construct sample entropy SamEn and Concordance Correlation based feature ψ from these EHG segments to quantify the synchrony and coherence of contraction. To test the effectiveness of the proposed method, 122 EHG recordings in the Icelandic EHG database were divided into two groups according to the time difference between the gestational ages at recording and at delivery (TTD). Both SamEn and ψ show clear difference in the two groups (p<10-5) even when measurements were made 120 h before delivery. Receiver operating characteristic curve analysis of these two features gave AUC values of 0.834 and 0.726 for discriminating imminent labor defined with TTD ≤ 24 h. The SamEn was significantly smaller in women (0.1433) of imminent labor group than in women (0.3774) of the pregnancy group. Using an optimal cutoff value of SamEn to identify imminent labor gives sensitivity, specificity, and accuracy as high as 0.909, 0.712 and 0.743, respectively. These results demonstrate superiority in comparing to the existing SOTA methods. This study is the first research work focusing on characterizing the synchrony property of contractions from the electrohysterography signals. Despite the very limited dataset used in the validation process, the promising results open a new direction to the use of electrohysterography in obstetrics.
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Affiliation(s)
- Junhua Shen
- Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Zhejiang Provincial Clinical Research Center for Obstetrics and Gynecology, Hangzhou, China
| | - Yan Liu
- College of Computer Science, Zhejiang University of Technology, Hangzhou, China
| | - Meiyu Zhang
- College of Computer Science, Zhejiang University of Technology, Hangzhou, China
| | - Alain Pumir
- Laboratoire de Physique, Ecole Normal Superieure de Lyon, Lyon, France
| | - Liangshan Mu
- Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Baohua Li
- Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Jinshan Xu
- College of Computer Science, Zhejiang University of Technology, Hangzhou, China.
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Garrett AS, Means SA, Roesler MW, Miller KJW, Cheng LK, Clark AR. Modeling and experimental approaches for elucidating multi-scale uterine smooth muscle electro- and mechano-physiology: A review. Front Physiol 2022; 13:1017649. [PMID: 36277190 PMCID: PMC9585314 DOI: 10.3389/fphys.2022.1017649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/21/2022] [Indexed: 11/13/2022] Open
Abstract
The uterus provides protection and nourishment (via its blood supply) to a developing fetus, and contracts to deliver the baby at an appropriate time, thereby having a critical contribution to the life of every human. However, despite this vital role, it is an under-investigated organ, and gaps remain in our understanding of how contractions are initiated or coordinated. The uterus is a smooth muscle organ that undergoes variations in its contractile function in response to hormonal fluctuations, the extreme instance of this being during pregnancy and labor. Researchers typically use various approaches to studying this organ, such as experiments on uterine muscle cells, tissue samples, or the intact organ, or the employment of mathematical models to simulate the electrical, mechanical and ionic activity. The complexity exhibited in the coordinated contractions of the uterus remains a challenge to understand, requiring coordinated solutions from different research fields. This review investigates differences in the underlying physiology between human and common animal models utilized in experiments, and the experimental interventions and computational models used to assess uterine function. We look to a future of hybrid experimental interventions and modeling techniques that could be employed to improve the understanding of the mechanisms enabling the healthy function of the uterus.
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Xu Y, Hao D, Taggart MJ, Zheng D. Regional identification of information flow termination of electrohysterographic signals: Towards understanding human uterine electrical propagation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 223:106967. [PMID: 35763875 DOI: 10.1016/j.cmpb.2022.106967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 06/13/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE The uterine electrohysterogram (EHG) contains important information about electrical signal propagation which may be useful to monitor and predict the progress of pregnancy towards parturition. Directed information processing has the potential to be of use in studying EHG recordings. However, so far, there is no directed information-based estimation scheme that has been applied to investigating the propagation of human EHG recordings. To realize this, the approach of directed information and its reliability and adaptability should be scientifically studied. METHODS We demonstrated an estimation scheme of directed information to identify the spatiotemporal relationship between the recording channels of EHG signal and assess the algorithm reliability initially using simulated data. Further, a regional identification of information flow termination (RIIFT) approach was developed and applied for the first time to extant multichannel EHG signals to reveal the terminal zone of propagation of the electrical activity associated with uterine contraction. RIIFT operates by estimating the pairwise directed information between neighboring EHG channels and identifying the location where there is the strongest inward flow of information. The method was then applied to publicly-available experimental data obtained from pregnant women with the use of electrodes arranged in a 4-by-4 grid. RESULTS Our results are consistent with the suggestions from the previous studies with the added identification of preferential sites of excitation termination - within the estimated area, the direction of surface action potential propagation towards the medial axis of uterus during contraction was discovered for 72.15% of the total cases, demonstrating that our RIIFT method is a potential tool to investigate EHG propagation for advancing our understanding human uterine excitability. CONCLUSIONS We developed a new approach and applied it to multichannel human EHG recordings to investigate the electrical signal propagation involved in uterine contraction. This provides an important platform for future studies to fill knowledge gaps in the spatiotemporal patterns of electrical excitation of the human uterus.
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Affiliation(s)
- Yuhang Xu
- Research Center for Intelligent Healthcare, Institute of Health and Wellbeing, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
| | - Dongmei Hao
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Michael J Taggart
- Biosciences Institute, Newcastle University, International Center for Life, Newcastle upon Tyne, NE1 4EP, UK
| | - Dingchang Zheng
- Research Center for Intelligent Healthcare, Institute of Health and Wellbeing, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
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Kuijsters NPM, Sammali F, Ye X, Blank C, Xu L, Mischi M, Schoot BC, Rabotti C. Propagation of spontaneous electrical activity in the ex vivo human uterus. Pflugers Arch 2020; 472:1065-1078. [PMID: 32691139 PMCID: PMC7376519 DOI: 10.1007/s00424-020-02426-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 05/21/2020] [Accepted: 06/26/2020] [Indexed: 12/18/2022]
Abstract
Contractions of the non-pregnant uterus play a key role in fertility. Yet, the electrophysiology underlying these contractions is poorly understood. In this paper, we investigate the presence of uterine electrical activity and characterize its propagation in unstimulated ex vivo human uteri. Multichannel electrohysterographic measurements were performed in five freshly resected human uteri starting immediately after hysterectomy. Using an electrode grid externally and an electrode array internally, measurements were performed up to 24 h after hysterectomy and compared with control. Up to 2 h after hysterectomy, we measured biopotentials in all included uteri. The median root mean squared (RMS) values of the external measurements ranged between 3.95 μV (interquartile range (IQR) 2.41–14.18 μV) and 39.4 μV (interquartile range (IQR) 10.84–105.64 μV) and were all significantly higher than control (median RMS of 1.69 μV, IQR 1.13–3.11 μV), consisting of chicken breast meat. The RMS values decreased significantly over time. After 24 h, the median RMS (1.27 μV, IQR 0.86–3.04 μV) was comparable with the control (1.69 μV, IQR 1.13–3.11 μV, p = 0.125). The internal measurements showed a comparable pattern over time, but overall lower amplitude. The measured biopotentials propagated over the uterine surface, following both a plane-wave as well as an erratic pattern. No clear pacemaker location nor a preferred propagation direction could be identified. These results show that ex vivo uteri can spontaneously generate propagating biopotentials and provide novel insight contributing to improving our understanding of the electrophysiology of the human non-pregnant uterus.
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Affiliation(s)
- Nienke P M Kuijsters
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands. .,Department of Obstetrics and Gynaecology, Catharina Hospital, Michelangelolaan 2, 5623 EJ, Eindhoven, the Netherlands.
| | - Federica Sammali
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands
| | - Xin Ye
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands
| | - Celine Blank
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands.,Department of Obstetrics and Gynaecology, University Hospital (UZ) Gent, C. Heymanslaan 10, 9000, Ghent, Belgium
| | - Lin Xu
- School of Information Science and Technology, ShanghaiTech University, Shanghai, China
| | - Massimo Mischi
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands
| | - Benedictus C Schoot
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands.,Department of Obstetrics and Gynaecology, Catharina Hospital, Michelangelolaan 2, 5623 EJ, Eindhoven, the Netherlands.,Department of Obstetrics and Gynaecology, University Hospital (UZ) Gent, C. Heymanslaan 10, 9000, Ghent, Belgium
| | - Chiara Rabotti
- Department of Electrical Engineering (Signal Processing Systems: Biomedical Diagnostics), Eindhoven Technical University, Post box 513, 5600 MB, Eindhoven, the Netherlands
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Zhang M, La Rosa PS, Eswaran H, Nehorai A. Estimating uterine source current during contractions using magnetomyography measurements. PLoS One 2018; 13:e0202184. [PMID: 30138376 PMCID: PMC6121809 DOI: 10.1371/journal.pone.0202184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 05/29/2018] [Indexed: 11/28/2022] Open
Abstract
Understanding the uterine source of the electrophysiological activity of
contractions during pregnancy is of scientific interest and potential clinical
applications. In this work, we propose a method to estimate uterine source
currents from magnetomyography (MMG) temporal course measurements on the
abdominal surface. In particular, we develop a linear forward model, based on
the quasistatic Maxwell’s equations and a realistic four-compartment volume
conductor, relating the magnetic fields to the source currents on the uterine
surface through a lead-field matrix. To compute the lead-field matrix, we use a
finite element method that considers the anisotropic property of the myometrium.
We estimate the source currents by minimizing a constrained least-squares
problem to solve the non-uniqueness issue of the inverse problem. Because we
lack the ground truth of the source current, we propose to predict the
intrauterine pressure from our estimated source currents by using an
absolute-value-based method and compare the result with real abdominal
deflection recorded during contractile activity. We test the feasibility of the
lead-field matrix by displaying the lead fields that are generated by putative
source currents at different locations in the myometrium: cervix and fundus,
left and right, front and back. We then illustrate our method by using three
synthetic MMG data sets, which are generated using our previously developed
multiscale model of uterine contractions, and three real MMG data sets, one of
which has simultaneous real abdominal deflection measurements. The numerical
results demonstrate the ability of our method to capture the local contractile
activity of human uterus during pregnancy. Moreover, the predicted intrauterine
pressure is in fair agreement with the real abdominal deflection with respect to
the timing of uterine contractions.
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Affiliation(s)
- Mengxue Zhang
- Preston M. Green Department of Electrical and Systems Engineering,
Washington University in Saint Louis, Saint Louis, Missouri, United States of
America
| | - Patricio S. La Rosa
- Geospatial Analytics, Global IT Analytics, Monsanto Company, Saint Louis,
Missouri, United States of America
| | - Hari Eswaran
- Department of Obstetrics and Gynecology, University of Arkansas for
Medical Sciences, Little Rock, Arkansas, United States of America
| | - Arye Nehorai
- Preston M. Green Department of Electrical and Systems Engineering,
Washington University in Saint Louis, Saint Louis, Missouri, United States of
America
- * E-mail:
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Comparison of electrohysterogram signal measured by surface electrodes with different designs: A computational study with dipole band and abdomen models. Sci Rep 2017; 7:17282. [PMID: 29229922 PMCID: PMC5725603 DOI: 10.1038/s41598-017-17109-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/21/2017] [Indexed: 11/23/2022] Open
Abstract
Non-invasive measurement of uterine activity using electrohysterogram (EHG) surface electrodes has been attempted to monitor uterine contraction. This study aimed to computationally compare the performance of acquiring EHG signals using monopolar electrode and three types of Laplacian concentric ring electrodes (bipolar, quasi-bipolar and tri-polar). With the implementation of dipole band model and abdomen model, the performances of four electrodes in terms of the local sensitivity were quantified by potential attenuation. Furthermore, the effects of fat and muscle thickness on potential attenuation were evaluated using the bipolar and tri-polar electrodes with different radius. The results showed that all the four types of electrodes detected the simulated EHG signals with consistency. That the bipolar and tri-polar electrodes had greater attenuations than the others, and the shorter distance between the origin and location of dipole band at 20 dB attenuation, indicating that they had relatively better local sensitivity. In addition, ANOVA analysis showed that, for all the electrodes with different outer ring radius, the effects of fat and muscle on potential attenuation were significant (all p < 0.01). It is therefore concluded that the bipolar and tri-polar electrodes had higher local sensitivity than the others, indicating that they can be applied to detect EHG effectively.
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7
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Mischi M, Chen C, Ignatenko T, de Lau H, Ding B, Oei SGG, Rabotti C. Dedicated Entropy Measures for Early Assessment of Pregnancy Progression From Single-Channel Electrohysterography. IEEE Trans Biomed Eng 2017; 65:875-884. [PMID: 28692959 DOI: 10.1109/tbme.2017.2723933] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Preterm birth is a large-scale clinical problem involving over 10% of infants. Diagnostic means for timely risk assessment are lacking and the underlying physiological mechanisms unclear. To improve the evaluation of pregnancy before term, we introduce dedicated entropy measures derived from a single-channel electrohysterogram (EHG). METHODS The estimation of approximate entropy (ApEn) and sample entropy (SampEn) is adjusted to monitor variations in the regularity of single-channel EHG recordings, reflecting myoelectrical changes due to pregnancy progression. In particular, modifications in the tolerance metrics are introduced for improving robustness to EHG amplitude fluctuations. An extensive database of 58 EHG recordings with 4 monopolar channels in women presenting with preterm contractions was manually annotated and used for validation. The methods were tested for their ability to recognize the onset of labor and the risk of preterm birth. Comparison with the best single-channel methods according to the literature was performed. RESULTS The reference methods were outperformed. SampEn and ApEn produced the best prediction of delivery, although only one channel showed a significant difference () between labor and nonlabor. The modified ApEn produced the best prediction of preterm delivery, showing statistical significance () in three channels. These results were also confirmed by the area under the receiver operating characteristic curve and fivefold cross validation. CONCLUSION The use of dedicated entropy estimators improves the diagnostic value of EHG analysis earlier in pregnancy. SIGNIFICANCE Our results suggest that changes in the EHG might manifest early in pregnancy, providing relevant prognostic opportunities for pregnancy monitoring by a practical single-channel solution.
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Degbedzui DK, Mills GA, Kaufmann EE. DEVELOPMENT OF UTERINE CONTRACTION MONITORING SYSTEM FOR RESOURCE-LIMITED SETTINGS. BIOMEDICAL ENGINEERING-APPLICATIONS BASIS COMMUNICATIONS 2016. [DOI: 10.4015/s1016237216500459] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A need assessment exercise at various resource-limited hospitals in Ghana revealed that a conventional method of monitoring uterine contractions is employed. This method is time consuming and ineffective with a likelihood of misrepresenting data on uterine contractions. There is therefore a need for a system that can potentially overcome the identified challenges. In this paper, the authors present the proof of concept for development of an automated uterine contraction monitoring system designed for use in resource-limited settings. Following the engineering design process, data were gathered to draft product specifications. Various concepts were evaluated and a mathematical model of chosen concept was built and simulated. A functional prototype was constructed to test the system’s ability to measure the frequency and average duration of muscle contractions over a specified interval. The results indicate the capability of the chosen concept to meet design specifications. The design can also be enhanced to provide the intensity of contractions.
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Affiliation(s)
- Derek Kweku Degbedzui
- Department of Biomedical Engineering, School of Engineering Sciences, University of Ghana, Legon, Accra, Ghana
| | - Godfrey A. Mills
- Department of Computer Engineering, School of Engineering Sciences, University of Ghana, Legon, Accra, Ghana
| | - Elsie Effah Kaufmann
- Department of Biomedical Engineering, School of Engineering Sciences, University of Ghana, Legon, Accra, Ghana
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Rabotti C, Mischi M. Propagation of electrical activity in uterine muscle during pregnancy: a review. Acta Physiol (Oxf) 2015; 213:406-16. [PMID: 25393600 DOI: 10.1111/apha.12424] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/13/2014] [Accepted: 11/07/2014] [Indexed: 11/29/2022]
Abstract
The uterine muscle (the myometrium) plays its most evident role during pregnancy, when quiescence is required for adequate nourishment and development of the foetus, and during labour, when forceful contractions are needed to expel the foetus and the other products of conception. The myometrium is composed of smooth muscle cells. Contraction is initiated by the spontaneous generation of electrical activity at the cell level in the form of action potentials. The mechanisms underlying uterine quiescence during pregnancy and electrical activation during labour remain largely unknown; as a consequence, the clinical management of preterm contractions during pregnancy and inefficient uterine contractility during labour remains suboptimal. In an effort to improve clinical management of uterine contractions, research has focused on understanding the propagation properties of the electrical activity of the uterus. Different perspectives have been undertaken, from animal and in vitro experiments up to clinical studies and dedicated methods for non-invasive parameter estimation. A comparison of the results is not straightforward due to the wide range of different approaches reported in the literature. However, previous studies unanimously reveal a unique complexity as compared to other organs in the pattern of uterine electrical activity propagation, which necessarily needs to be taken into consideration for future studies to be conclusive. The aim of this review is to structure current variegated knowledge on the properties of the uterus in terms of pacemaker position, pattern, direction and speed of the electrical activity during pregnancy and labour.
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Affiliation(s)
- C. Rabotti
- Electrical Engineering Department; Eindhoven University of Technology; Eindhoven the Netherlands
| | - M. Mischi
- Electrical Engineering Department; Eindhoven University of Technology; Eindhoven the Netherlands
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10
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Dynamic Behavior of Uterine Contractions: An Approach Based on Source Localization and Multiscale Modeling. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/978-3-319-11680-8_42] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Lange L, Vaeggemose A, Kidmose P, Mikkelsen E, Uldbjerg N, Johansen P. Velocity and directionality of the electrohysterographic signal propagation. PLoS One 2014; 9:e86775. [PMID: 24466235 PMCID: PMC3897754 DOI: 10.1371/journal.pone.0086775] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/15/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE The initiation of treatment for women with threatening preterm labor requires effective distinction between true and false labor. The electrohysterogram (EHG) has shown great promise in estimating and classifying uterine activity. However, key issues remain unresolved and no clinically usable method has yet been presented using EHG. Recent studies have focused on the propagation velocity of the EHG signals as a potential discriminator between true and false labor. These studies have estimated the propagation velocity of individual spikes of the EHG signals. We therefore focus on estimating the propagation velocity of the entire EHG burst recorded during a contraction in two dimensions. STUDY DESIGN EHG measurements were performed on six women in active labor at term, and a total of 35 contractions were used for the estimation of propagation velocity. The measurements were performed using a 16-channel two-dimensional electrode grid. The estimates were calculated with a maximum-likelihood approach. RESULTS The estimated average propagation velocity was 2.18 (±0.68) cm/s. No single preferred direction of propagation was found. CONCLUSION The propagation velocities estimated in this study are similar to those reported in other studies but with a smaller intra- and inter-patient variation. Thus a potential tool has been established for further studies on true and false labor contractions.
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Affiliation(s)
- Lasse Lange
- Department of Engineering, Faculty of Science and Technology, Aarhus University, Aarhus, Denmark
| | - Anders Vaeggemose
- Department of Engineering, Faculty of Science and Technology, Aarhus University, Aarhus, Denmark
| | - Preben Kidmose
- Department of Engineering, Faculty of Science and Technology, Aarhus University, Aarhus, Denmark
| | - Eva Mikkelsen
- Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Uldbjerg
- Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark
| | - Peter Johansen
- Department of Engineering, Faculty of Science and Technology, Aarhus University, Aarhus, Denmark
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Comparison of non-invasive electrohysterographic recording techniques for monitoring uterine dynamics. Med Eng Phys 2013; 35:1736-43. [DOI: 10.1016/j.medengphy.2013.07.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 05/30/2013] [Accepted: 07/23/2013] [Indexed: 11/18/2022]
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13
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de Lau H, Rabotti C, Haazen N, Oei SG, Mischi M. Towards improving uterine electrical activity modeling and electrohysterography: ultrasonic quantification of uterine movements during labor. Acta Obstet Gynecol Scand 2013; 92:1323-6. [DOI: 10.1111/aogs.12233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 08/01/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Hinke de Lau
- Department of Obstetrics and Gynecology; Máxima Medical Center; Veldhoven; the Netherlands
| | - Chiara Rabotti
- Department of Electrical Engineering; University of Technology Eindhoven; Eindhoven; the Netherlands
| | - Nicole Haazen
- Department of Electrical Engineering; University of Technology Eindhoven; Eindhoven; the Netherlands
| | - S. Guid Oei
- Department of Obstetrics and Gynecology; Máxima Medical Center; Veldhoven; the Netherlands
| | - Massimo Mischi
- Department of Electrical Engineering; University of Technology Eindhoven; Eindhoven; the Netherlands
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Laforet J, Marque C. Preliminary global sensitivity analysis of a uterine electrical activity model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:7440-3. [PMID: 24111465 DOI: 10.1109/embc.2013.6611278] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A comprehensive multiscale model of the uterine muscle electrical activity would permit understanding the important link between the genesis and evolution of the action potential at the cell level and the process leading to labor. Understanding this link can open the way to more effective tools for the prediction of labor and prevention of preterm delivery.
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15
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Mikkelsen E, Johansen P, Fuglsang-Frederiksen A, Uldbjerg N. Electrohysterography of labor contractions: propagation velocity and direction. Acta Obstet Gynecol Scand 2013; 92:1070-8. [PMID: 23730731 DOI: 10.1111/aogs.12190] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 05/27/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Electrohysterographic assessment of the propagation velocity of uterine depolarization has been introduced as a promising predictor of preterm labor. Therefore, the objectives of this study were to characterize the uterine electrohysterographic signals during labor and to determine the propagation velocity and propagation direction of electrohysterographic signals. DESIGN Descriptive study. SETTING Department of Obstetrics and Gynecology, Aarhus University Hospital, Denmark. POPULATION Eight women in active labor at term. METHODS Electrohysterograms (three channels) were recorded using surface electrodes placed abdominally along the vertical median axis with an inter-electrode distance of 6.5-11.2 cm. In total, 89 contractions were analyzed. RESULTS Electrohysterographic characteristics: The duration of the contractions was 61.0 ± 18.0 s (mean ± SD). The median frequency of the power spectrum density was 0.51 (0.44; 0.51) Hz (median; 10th; 90th percentile). The greatest signal magnitude was obtained by the electrode in the centermost position. The propagation velocity: 2.15 (0.66; 13.8) cm/s in the upper part and 1.53 (0.58; 6.7) cm/s in the lower part of the uterus. Propagation direction: Both downward (58%) and upward (42%) propagation of the electrohysterographic signals occurred. Moreover, downward and upward propagations were recorded simultaneously in the upper and lower part of the uterus, suggesting a multidirectional propagation pattern. CONCLUSIONS Labor contractions, expressed by electrohysterographic signals, propagate both in the downward and upward direction, a phenomenon that must be taken into account when determining the propagation velocity for preterm labor diagnostics.
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Affiliation(s)
- Eva Mikkelsen
- Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark.
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16
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Sharp GC, Saunders PTK, Norman JE. Computer models to study uterine activation at labour. Mol Hum Reprod 2013; 19:711-7. [PMID: 23778245 DOI: 10.1093/molehr/gat043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Improving our understanding of the initiation of labour is a major aim of modern obstetric research, in order to better diagnose and treat pregnant women in which the process occurs abnormally. In particular, increased knowledge will help us identify the mechanisms responsible for preterm labour, the single biggest cause of neonatal morbidity and mortality. Attempts to improve our understanding of the initiation of labour have been restricted by the inaccessibility of gestational tissues to study during pregnancy and at labour, and by the lack of fully informative animal models. However, computer modelling provides an exciting new approach to overcome these restrictions and offers new insights into uterine activation during term and preterm labour. Such models could be used to test hypotheses about drugs to treat or prevent preterm labour. With further development, an effective computer model could be used by healthcare practitioners to develop personalized medicine for patients on a pregnancy-by-pregnancy basis. Very promising work is already underway to build computer models of the physiology of uterine activation and contraction. These models aim to predict changes and patterns in uterine electrical excitation during term labour. There have been far fewer attempts to build computer models of the molecular pathways driving uterine activation and there is certainly scope for further work in this area. The integration of computer models of the physiological and molecular mechanisms that initiate labour will be particularly useful.
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Affiliation(s)
- G C Sharp
- MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
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Laforet J, Rabotti C, Mischi M, Marque C. Improved multi-scale modeling of uterine electrical activity. Ing Rech Biomed 2013. [DOI: 10.1016/j.irbm.2012.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Rabotti C, de Lau H, Haazen N, Oei G, Mischi M. Ultrasound analysis of the uterine wall movement for improved electrohysterographic measurement and modeling. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:7436-7439. [PMID: 24111464 DOI: 10.1109/embc.2013.6611277] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
During pregnancy, analysis of the electrohysterogram (EHG), which measures the uterine electrical activity, can provide a fundamental contribution for the assessment of uterine contractions and the diagnosis of preterm labor. However, several aspects concerning uterine physiology and its link with EHG measurements are still unclear. As a consequence, the EHG is not yet part of the clinical practice. There is general consensus that modeling and analysis of the EHG can be improved only by understanding and integrating the main properties of the uterine physiology at different levels, e:g:, cellular, tissue, and organ, and of different nature, e:g:, electrical, mechanical, and structural. In this study, we use transabdominal ultrasound (US) measurements to investigate the mechanical changes that the uterus undergoes during pregnancy under the effect of contractions. We refer to this measurement as mechanohysterogram. Analysis of the mechanohysterogram highlights, for the first time, two phenomena that can influence EHG signal interpretation, namely, changes in uterine wall thickness during contractions and respiration-induced uterine wall movements. Our results suggest that these phenomena can affect the interpretation of the EHG and should therefore be taken into account for accurate modeling and assessment of the uterine electrical activity.
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Marque C, Laforêt J, Rabotti C, Alexandersson A, Germain G, Gondry J, Karlsson B, Leskosek B, Mischi M, Muszinski C, Oei G, Peuscher J, Rudel D. A multiscale model of the electrohysterogram the BioModUE_PTL project. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:7448-7451. [PMID: 24111467 DOI: 10.1109/embc.2013.6611280] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The electrohysterogram (EHG) is a promising means of monitoring pregnancy and of detecting a risk of preterm labor. To improve our understanding of the EHG as well as its relationship with the physiologic phenomena involved in uterine contractility, we plan to model these phenomena in terms of generation and propagation of uterine electrical activity. This activity can be realistically modeled by representing the principal ionic dynamics at the cell level, the propagation of electrical activity at the tissue level and then the way it is reflected on the skin surface through the intervening tissue. We present in this paper the different steps leading to the development and validation of a biophysics based multiscale model of the EHG, going from the cell to the electrical signal measured on the abdomen.
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La Rosa PS, Eswaran H, Preissl H, Nehorai A. Multiscale forward electromagnetic model of uterine contractions during pregnancy. BMC MEDICAL PHYSICS 2012; 12:4. [PMID: 23126570 PMCID: PMC3605117 DOI: 10.1186/1756-6649-12-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 10/14/2012] [Indexed: 11/10/2022]
Abstract
BACKGROUND Analyzing and monitoring uterine contractions during pregnancy is relevant to the field of reproductive health assessment. Its clinical importance is grounded in the need to reliably predict the onset of labor at term and pre-term. Preterm births can cause health problems or even be fatal for the fetus. Currently, there are no objective methods for consistently predicting the onset of labor based on sensing of the mechanical or electrophysiological aspects of uterine contractions. Therefore, modeling uterine contractions could help to better interpret such measurements and to develop more accurate methods for predicting labor. In this work, we develop a multiscale forward electromagnetic model of myometrial contractions during pregnancy. In particular, we introduce a model of myometrial current source densities and compute its magnetic field and action potential at the abdominal surface, using Maxwell's equations and a four-compartment volume conductor geometry. To model the current source density at the myometrium we use a bidomain approach. We consider a modified version of the Fitzhugh-Nagumo (FHN) equation for modeling ionic currents in each myocyte, assuming a plateau-type transmembrane potential, and we incorporate the anisotropic nature of the uterus by designing conductivity-tensor fields. RESULTS We illustrate our modeling approach considering a spherical uterus and one pacemaker located in the fundus. We obtained a travelling transmembrane potential depolarizing from -56 mV to -16 mV and an average potential in the plateau area of -25 mV with a duration, before hyperpolarization, of 35 s, which is a good approximation with respect to the average recorded transmembrane potentials at term reported in the technical literature. Similarly, the percentage of myometrial cells contracting as a function of time had the same symmetric properties and duration as the intrauterine pressure waveforms of a pregnant human myometrium at term. CONCLUSIONS We introduced a multiscale modeling approach of uterine contractions which allows for incorporating electrophysiological and anatomical knowledge of the myometrium jointly. Our results are in good agreement with the values reported in the experimental technical literature, and these are potentially important as a tool for helping in the characterization of contractions and for predicting labor using magnetomyography (MMG) and electromyography (EMG).
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Affiliation(s)
- Patricio S La Rosa
- Department of Electrical and Systems Engineering, Washington University, Saint Louis, Missouri 63130, USA.
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21
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Abstract
INTRODUCTION The purpose of this study was to evaluate the use of intrauterine pressure catheters (IUPCs) to measure uterine activity during the third stage of labor. METHODS The study was conducted in a tertiary-care center. All births were attended by certified nurse-midwives. Low-risk pregnant women at term gestation had intrauterine monitoring attempted during the third stage of labor. Data were analyzed using descriptive statistics and analysis of variance. RESULTS Of the 36 women in the study, 19 had clear contractions recorded, 4 had unclear contractions, and 13 had flat tracings. The IUPC was useful for measuring uterine activity in a small number of women during the third stage of labor. When measured, uterine contractions were variable in strength and frequency. DISCUSSION Intrauterine pressure catheters can be used as a measurement of uterine activity during the third stage of labor and should be considered for future research about third-stage physiology. Further work is needed to determine the best procedure for placement, and IUPC use before expulsion of the placenta will not be useful in all women. Effective measurement of uterine activity may guide future research on interventions to reduce the risk of postpartum hemorrhage.
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Affiliation(s)
- Mavis N Schorn
- Vanderbilt University School of Nursing, Nashville, Tennessee, USA.
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Laforet J, Rabotti C, Terrien J, Mischi M, Marque C. Toward a multiscale model of the uterine electrical activity. IEEE Trans Biomed Eng 2011; 58:3487-90. [PMID: 21968708 DOI: 10.1109/tbme.2011.2167970] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A comprehensive multiscale model of the uterine muscle electrical activity would permit understanding the important link between the genesis and evolution of the action potential at the cell level and the process leading to labor. Understanding this link can open the way to more effective tools for the prediction of labor and prevention of preterm delivery. A first step toward the realization of such a model is presented here. By using as starting point a previously published model of the generation of the uterine muscle action potential at the cell level, a significant reduction of the model complexity is here achieved in order to simulate 2-D propagation of the cellular activity at the uterine tissue level, for tissue strips of arbitrary dimension. From the obtained dynamic behavior of the electrical activity simulated at the tissue level, the use of a previously validated volume conductor model at the organ level permits us to simulate the electrohysterogram as recorded on the abdominal surface by an electrode array. Qualitative evaluation of the model at the cell level and at the organ level confirms the potential of the proposed multiscale approach for further refinement and extension aiming at clinical application.
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Affiliation(s)
- Jeremy Laforet
- Université de Technologie de Compiègne, CNRS UMR 6600, Biomecanique et Bioingenierie, France.
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Rabotti C, Mischi M. Two-dimensional estimation of the electrohysterographic conduction velocity. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2011; 2010:4262-5. [PMID: 21096643 DOI: 10.1109/iembs.2010.5627172] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Propagation of action potentials (APs) through an adequate number of uterine muscle cells induces contraction of the uterus. Monitoring uterine contractions, as the first sign of labor, can provide important information on the course of pregnancy and delivery. Unfortunately, current monitoring methods are affected by serious limitations. The electrohysterogram (EHG), which is the noninvasive recording of the APs propagating through the uterine smooth muscle cells, is here analyzed as a potential alternative to current methods. We focus on estimating the conduction velocity (CV) of surface APs extracted from an EHG recorded in a multielectrode configuration. In this work, a two-dimensional, 64-channel, high density electrode grid is used. Maximum likelihood methods are employed for analyzing the EHG AP propagation in two dimensions. The use of different weighting strategies of the derived cost function is introduced to deal with poor interchannel signal similarity. The presented methods were evaluated by specific simulations proving the best weighting strategy to lead to an accuracy improvement of 58%. EHG measurements on women with uterine contractions confirmed the feasibility of the method by leading to values of conduction velocity within the expected physiological range.
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Affiliation(s)
- Chiara Rabotti
- Department of Electrical Engineering, Eindhoven University of technology, the Netherlands.
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Rabotti C, Mischi M, Oei SG, Bergmans JWM. Noninvasive estimation of the electrohysterographic action-potential conduction velocity. IEEE Trans Biomed Eng 2010; 57:2178-87. [PMID: 20460202 DOI: 10.1109/tbme.2010.2049111] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electrophysiological monitoring of the fetal-heart and the uterine-muscle activity, referred to as an electrohysterogram, is essential to permit timely treatment during pregnancy. While remarkable progress is reported for fetal-cardiac-activity monitoring, the electrohysterographic (EHG) measurement and interpretation remain challenging. In particular, little attention has been paid to the analysis of the EHG propagation, whose characteristics might be predictive of the preterm delivery. Therefore, this paper focuses, for the first time, on the noninvasive estimation of the conduction velocity of the EHG-action potentials. To this end, multichannel EHG recording and surface high-density electrodes are used. A maximum-likelihood method is employed for analyzing the EHG-action-potential propagation in two dimensions. The use of different weighting strategies of the derived cost function is introduced to deal with the poor signal similarity between different channels. The presented methods were evaluated by specific simulations proving the best weighting strategy to lead to an accuracy improvement of 56.7%. EHG measurements on ten women with uterine contractions confirmed the feasibility of the method by leading to conduction velocity values within the expected physiological range.
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Affiliation(s)
- Chiara Rabotti
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven 5600MB, The Netherlands.
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