Electrohysterography of labor contractions: propagation velocity and direction

Mikkelsen, E.; Johansen, Peter; Fuglsang-Frederiksen, Anders; Uldbjerg, Niels

doi:10.1111/aogs.12190

Cited by 32 publications

(30 citation statements)

References 23 publications

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“…The estimated velocities are comparable to those reported in other EHG studies [22], [23], [30] but with a smaller intra- and inter-patient variation. While other studies report that the estimated velocities are within the physiological expected range, we must stress the fact that, to our knowledge, no previous studies have measured the propagation velocity of electrical signals directly on the human myometrium.…”

Section: Discussionsupporting

confidence: 86%

Velocity and Directionality of the Electrohysterographic Signal Propagation

et al. 2014

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ObjectiveThe 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 DesignEHG 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.ResultsThe estimated average propagation velocity was 2.18 (±0.68) cm/s. No single preferred direction of propagation was found.ConclusionThe 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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Section: Discussionsupporting

confidence: 86%

Velocity and Directionality of the Electrohysterographic Signal Propagation

et al. 2014

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“…Based on our present observations, EMG signals preceding myometrial contractions in the pig’s uterus are propagated relatively uniformly in both cervico-tubal and tubo-cervical directions. This is in agreement with the results of myoelectrical burst analyses in women where both upward and multidirectional propagation patterns have been reported [33, 34]. This “mixed” propagation pattern may serve to facilitate sperm transport along the uterine horns and/or re-distribution of semen throughout the two horns in the case of unilateral deposition of semen [35].…”

Section: Discussionsupporting

confidence: 89%

“…All authors recorded myometrial activity directly within the myometrium (EMG) [22, 28, 29, 30, 31] or used intrauterine pressure (IUP) [27]. An alternative method for monitoring the uterine activity based on surface EMG—EHG (electrohysterogram) allowed to application from 3 [32] to 16 [33] and 64 [20] active electrodes located on abdomen skin. The needle EMG picked up the bioelectrical signal directly associated with the muscular activity of myometrium, while EHG collected signal abundant in noise generated between cells and electrodes.…”

Section: Discussionmentioning

confidence: 99%

Biomathematical pattern of EMG signal propagation in smooth muscle of the non-pregnant porcine uterus

2017

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Uterine contractions are generated by myometrial smooth muscle cells (SMCs) that comprise most of the myometrial layer of the uterine wall. Aberrant uterine motility (i.e., hypo- or hyper-contractility or asynchronous contractions) has been implicated in the pathogenesis of infertility due to the failure of implantation, endometriosis and abnormal estrous cycles. The mechanism whereby the non-pregnant uterus initiates spontaneous contractions remains poorly understood. The aim of the present study was to employ linear synchronization measures for analyzing the pattern of EMG signal propagation (direction and speed) in smooth muscles of the non-pregnant porcine uterus in vivo using telemetry recording system. It has been revealed that the EMG signal conduction in the uterine wall of the non-pregnant sow does not occur at random but it rather exhibits specific directions and speed. All detectable EMG signals moved along the uterine horn in both cervico-tubal and tubo-cervical directions. The signal migration speed could be divided into the three main types or categories: i. slow basic migration rhythm (SBMR); ii. rapid basic migration rhythm (RBMR); and iii. rapid accessory migration rhythm (RAMR). In conclusion, the EMG signal propagation in smooth muscles of the porcine uterus in vivo can be assessed using a linear synchronization model. Physiological pattern of the uterine contractile activity determined in this study provides a basis for future investigations of normal and pathologicall myogenic function of the uterus.

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“…However, there is a significant doubt that myometrial action potentials travel in straight paths. In sheep (Parkington et al 1988), rodent ( Lammers et al 2008), and human (Mikkelsen et al 2013, Rabotti & Mischi 2015 action potentials are not found to travel linearly. The highest resolution electrical mapping of myometrium is in the guinea pig, which reveals that action potentials diverge and loop through tortuous paths, self-terminate, and usually do not propagate more than a few centimeters (Lammers et al 2008) (Fig.…”

Section: Problems With Action Potential Propagation As a Mechanism Fomentioning

confidence: 89%

Mechanotransduction mechanisms for coordinating uterine contractions in human labor

Young¹

2016

Reproduction

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This review presents evolving concepts of how the human uterus contracts in pregnancy, with emphasis on the mechanisms of long-distance signaling. Action potential propagation has historically been assumed to be the sole mechanism for signaling and tissue recruitment over both short and long distances. However, data in animals and humans indicate that a single action potential does not travel distances greater than a few centimeters. To address this enigma, a long-distance signaling mechanism based on hydraulic signaling and mechanotransduction is developed. By combining this mechanism for long-distance signaling with the action potential propagation mechanism for signaling over short distances, a comprehensive dual mechanism model (or 'dual model') of uterine function is formulated. Mechanotransduction is an accepted phenomenon of myometrium, but the dual model identifies mechanotransduction as relevant to normal labor. For hydraulic signaling, a local contraction slightly increases intrauterine pressure, which globally increases wall tension. increased wall tension then mechanically induces additional local contractions that further raise pressure. This leads to robust, positive feedback recruitment that explains the emergence of consistently strong contractions of human labor. Three key components of the dual model -rapid long-distance signaling, mechanical triggering, and electrical activityconverge with the concept of mechanically sensitive electrogenic pacemakers distributed throughout the wall. The dual model retains excitation-contraction coupling and action potential propagation for signaling over short distances (<10 cm) and hence is an extension of the action potential model rather than a replacement.Reproduction (2016) 152 R51-R61

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Electrohysterography of labor contractions: propagation velocity and direction

Abstract: 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.

Cited by 32 publications

References 23 publications

Velocity and Directionality of the Electrohysterographic Signal Propagation

Velocity and Directionality of the Electrohysterographic Signal Propagation

Biomathematical pattern of EMG signal propagation in smooth muscle of the non-pregnant porcine uterus

Mechanotransduction mechanisms for coordinating uterine contractions in human labor

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