Toward noninvasive monitoring of ongoing electrical activity of human uterus and fetal heart and brain

Neurologic Sequelae Associated with Hypertensive Disorders of Pregnancy

Hypertensive disorders of pregnancy (HDP) contribute to adverse gene-environment interactions prior to conception and continue throughout pregnancy. Embryonic/fetal brain disorders occur from interactions between genetic susceptibilities interacting with acquired diseases or conditions affecting the maternal/placental fetal (MPF) triad. Trimester-specific pathophysiological mechanisms, such as maternal immune activation and ischemic placental syndrome, contribute to adverse peripartum, neonatal and childhood outcomes. Two diagnostic approaches provide timelier diagnoses over the first 1000 days from conception until two years of age. Horizontal analyses assess the maturation of the triad, neonate and child. Vertical analyses consider systems-biology from genetic, molecular, cellular, tissue through organ networks during each developmental niche. Disease expressions associated with HDP have cumulative adverse effects across the lifespan when subjected to subsequent adverse events. Critical/sensitive periods of developmental neuroplasticity over the first 1000 days are more likely to result in permanent sequelae. Novel diagnostic approaches, beginning during pre-conception, will facilitate the development of effective preventive, rescue and reparative neurotherapeutic strategies in response to HDP-related trimester-specific disease pathways. Public health policies require the inclusion of women's health advocacy during and beyond their reproductive years to reduce sequelae experienced by mothers and their offspring. A lower global burden of neurologic disease from HDP will benefit future generations.

Uterus Modeling from Cell to Organ Level: towards Better Understanding of Physiological Basis of Uterine Activity

The relatively limited understanding of the physiology of uterine activation prevents us from achieving optimal clinical outcomes for managing serious pregnancy disorders such as preterm birth or uterine dystocia. There is increasing awareness that multi-scale computational modeling of the uterus is a promising approach for providing a qualitative and quantitative description of uterine physiology. The overarching objective of such approach is to coalesce previously fragmentary information into a predictive and testable model of uterine activity that, in turn, informs the development of new diagnostic and therapeutic approaches to these pressing clinical problems. This article assesses current progress towards this goal. We summarize the electrophysiological basis of uterine activation as presently understood and review recent research approaches to uterine modeling at different scales from single cell to tissue, whole organ and organism with particular focus on transformative data in the last decade. We describe the positives and limitations of these approaches, thereby identifying key gaps in our knowledge on which to focus, in parallel, future computational and biological research efforts.

The haemodynamics of the human placenta in utero

We have used magnetic resonance imaging (MRI) to provide important new insights into the function of the human placenta in utero. We have measured slow net flow and high net oxygenation in the placenta in vivo, which are consistent with efficient delivery of oxygen from mother to fetus. Our experimental evidence substantiates previous hypotheses on the effects of spiral artery remodelling in utero and also indicates rapid venous drainage from the placenta, which is important because this outflow has been largely neglected in the past. Furthermore, beyond Braxton Hicks contractions, which involve the entire uterus, we have identified a new physiological phenomenon, the ‘utero-placental pump’, by which the placenta and underlying uterine wall contract independently of the rest of the uterus, expelling maternal blood from the intervillous space.

MRI provides important new insights into the function of the human placenta, revealing slow net flow and high, uniform oxygenation in healthy pregnancies, detecting changes that will lead to compromised oxygen delivery to the fetus in preeclampsia, and identifying a new physiological phenomenon, the ‘utero-placental pump’.

Exploring early human brain development with structural and physiological neuroimaging

Early brain development, from the embryonic period to infancy, is characterized by rapid structural and functional changes. These changes can be studied using structural and physiological neuroimaging methods. In order to optimally acquire and accurately interpret this data, concepts from adult neuroimaging cannot be directly transferred. Instead, one must have a basic understanding of fetal and neonatal structural and physiological brain development, and the important modulators of this process. Here, we first review the major developmental milestones of transient cerebral structures and structural connectivity (axonal connectivity) followed by a summary of the contributions from ex vivo and in vivo MRI. Next, we discuss the basic biology of neuronal circuitry development (synaptic connectivity, i.e. ensemble of direct chemical and electrical connections between neurons), physiology of neurovascular coupling, baseline metabolic needs of the fetus and the infant, and functional connectivity (defined as statistical dependence of low-frequency spontaneous fluctuations seen with functional magnetic resonance imaging (fMRI)). The complementary roles of magnetic resonance imaging (MRI), electroencephalography (EEG), magnetoencephalography (MEG), and near-infrared spectroscopy (NIRS) are discussed. We include a section on modulators of brain development where we focus on the placenta and emerging placental MRI approaches. In each section we discuss key technical limitations of the imaging modalities and some of the limitations arising due to the biology of the system. Although neuroimaging approaches have contributed significantly to our understanding of early brain development, there is much yet to be done and a dire need for technical innovations and scientific discoveries to realize the future potential of early fetal and infant interventions to avert long term disease.

Estimating uterine source current during contractions using magnetomyography measurements

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.

A Comparison of Five Algorithms for Fetal Magnetocardiography Signal Extraction

Fetal magnetocardiography (fMCG) provides accurate and reliable measurements of electrophysiological events in the fetal heart and is capable of studying fetuses with congenital heart diseases. A variety of techniques exist to extract the fMCG signal with the demand for non-invasively obtained fetal cardiac information. To the best of our knowledge, there is no comparative study published in the field as to how the various extraction algorithms perform. We perform a comparative study of the ability of five methods to extract the fMCG using real biomagnetic signals, two of those methods are applied to real fMCG data for the first time. Biomagnetic signals were recorded and processed with each of the five methods to obtain fMCG. The R peaks of the fMCG traces were obtained via a peak-detection algorithm. From whole recording for each method, the fetal heart rate (FHR) was calculated and used to perform FHR variability (FHRV) analysis. Additionally, we calculated durations from the PQRST complex from time-averaged data during sinus rhythm. The five methods recovered the fMCG signals, but two of them were able to extract cleaner fMCG and the morphology was observed from the continuous data. The time-averaged data showed very similar morphologies between methods, but two of them displayed a signal amplitude reduction on the R-waves and T-waves. Values of PQRST durations, FHR and FHRV were in the range of previous fetal cardiac studies. We have compared five methods for fMCG extraction and showed their ability to perform fMCG analysis.