Andrea Fanelli

Quantitative Assessment of Fetal Well-Being Through CTG Recordings: A New Parameter Based on Phase-Rectified Signal Average

Since the 1980s, cardiotocography (CTG) has been the most diffused technique to monitor fetal well-being during pregnancy. CTG consists of the simultaneous recording of fetal heart rate (FHR) signal and uterine contractions and its interpretation is usually performed through visual inspection by trained obstetric personnel. To reduce inter- and intraobserver variabilities and to improve the efficacy of prenatal diagnosis, new quantitative parameters, extracted from the CTG digitized signals, have been proposed as additional tools in the clinical diagnosis process. In this paper, a new parameter computed on FHR time series and based on the phase-rectified signal average curve (PRSA) is introduced. It is defined as acceleration phase-rectified slope (APRS) or deceleration phase-rectified slope (DPRS) depending on the slope sign of the PRSA curve. The new PRSA parameter was applied to FHR time series of 61 healthy and 61 intrauterine growth restricted (IUGR) fetuses during CTG nonstress tests. Performance of APRS and DPRS was compared with 1) the results provided by other parameters extracted from the PRSA curve itself but already existing in the literature, and 2) other clinical indices provided by computerized cardiotocographic systems. APRS and DPRS indices performed better than any other parameter in this study in the distinction between healthy and IUGR fetuses. Our results suggest this new index might reliably contribute to the quality of early fetal diagnosis.

Monitoring fetal heart rate during pregnancy: contributions from advanced signal processing and wearable technology.

Monitoring procedures are the basis to evaluate the clinical state of patients and to assess changes in their conditions, thus providing necessary interventions in time. Both these two objectives can be achieved by integrating technological development with methodological tools, thus allowing accurate classification and extraction of useful diagnostic information. The paper is focused on monitoring procedures applied to fetal heart rate variability (FHRV) signals, collected during pregnancy, in order to assess fetal well-being. The use of linear time and frequency techniques as well as the computation of non linear indices can contribute to enhancing the diagnostic power and reliability of fetal monitoring. The paper shows how advanced signal processing approaches can contribute to developing new diagnostic and classification indices. Their usefulness is evaluated by comparing two selected populations: normal fetuses and intra uterine growth restricted (IUGR) fetuses. Results show that the computation of different indices on FHRV signals, either linear and nonlinear, gives helpful indications to describe pathophysiological mechanisms involved in the cardiovascular and neural system controlling the fetal heart. As a further contribution, the paper briefly describes how the introduction of wearable systems for fetal ECG recording could provide new technological solutions improving the quality and usability of prenatal monitoring.

Prototype of a wearable system for remote fetal monitoring during pregnancy

Fetal Heart Rate (FHR) monitoring gives important information about the fetus health state during pregnancy. This paper presents a new prototype for remote fetal monitoring. The device will allow to monitor FHR in a domiciliary context and to send fetal ECG traces to a hospital facility, where clinicians can interpret them. In this way the mother could receive prompt feedback about fetal wellbeing. The system is characterized by two units: (i) a wearable unit endowed with textile electrodes for abdominal ECG recordings and with a Field Programmable Gate Array (FPGA) board for fetal heart rate (FHR) extraction; (ii) a dock station for the transmission of the data through the telephone line. The system will allow to reduce costs in fetal monitoring, improving the assessment of fetal conditions. The device is actually in development state. In this paper, the most crucial aspects behind its fulfillment are discussed.

Telefetalcare: A first prototype of a wearable fetal electrocardiograph

Fetal heart rate monitoring is fundamental to infer information about fetal health state during pregnancy. The cardiotocography (CTG) is the most common antepartum monitoring technique. Abdominal ECG recording represents the most valuable alternative to cardiotocography, as it allows passive, non invasive and long term fetal monitoring. Unluckily fetal ECG has low SNR and needs to be extracted from abdominal recordings using ad hoc algorithms. This work describes a prototype of a wearable fetal ECG electrocardiograph. The system has flat band frequency response between 1–60Hz and guarantees good signal quality. It was tested on pregnant women between the 30th and 34th gestational week. Several electrodes configurations were tested, in order to identify the best solution. Implementation of a simple algorithm for FECG extraction permitted the reliable detection of maternal and fetal QRS complexes. The system will allow continuative and deep screening of fetal heart rate, introducing the possibility of home fetal monitoring.

Multivariate analysis based on linear and non-linear FHR parameters for the identification of IUGR fetuses

Fetal Heart Rate (FHR) monitoring represents a powerful tool for checking the arousal of pathological fetal conditions during pregnancy. This paper proposes a multivariate approach for the discrimination of Normal and Intra Uterine Growth Restricted (IUGR) fetuses based on a small set of parameters computed on the FHR signal. We collected FHR recordings in a population of 120 fetuses (60 normals and 60 IUGRs) at approximately the same gestational week through a standard CTG non-stress test. A set of 8 linear and non-linear indices were selected and computed on each recording, on the basis of their “stand-alone” discriminative properties, demonstrated in previous studies. By using the Orange® data mining suite we checked various multivariate discrimination models. The results show that a Logistic Regression performed on a limited set of only 4 parameters can reach 92.5% accuracy in the correct identification of fetuses, with 93% sensitivity and 91.5% specificity.

A Mobile Remote Monitoring Service for Measuring Fetal Heart Rate

This paper illustrates an architecture and an implementation of a tele-monitoring service measuring fetal heart rate. The service helps pregnant women in self-accomplishing the exam at their homes wearing a textile garment connected to an 8-channel ECG monitoring device which delivers the signal to a mobile device such as a smartphone or tablet. The mobile device then sends the acquired signal over the air to a clinic server where further processing is performed and a medical report is eventually issued. A web application is available on the clinic server in order to enable the medical staff to retrieve and classify the acquired signals.

Novel Image Processing Methods for the Analysis of Calcium Dynamics in Glial Cells

Calcium (Ca2+) waves and Ca2+ oscillations within cells initiate a wide range of physiological processes including control of cell signaling, gene expression, secretion, and cell migration. A thorough analysis of Ca2+ waves in glial cells provides information not only about the subcellular location of signaling processing events but also about nonneuronal or intercellular signaling pathways, their timing, routes, spatial domains, and coordination. In this study, three novel image processing methods have been applied to the study of Ca2+ dynamics in cells. These bring additional information to the methods already available in the literature, providing insight into the analysis of calcium dynamics in fluorescence recordings and defining bidimensional maps that give a complete and detailed description of calcium intracellular behavior. The application of these processing methods to glial cells highlighted the complex 2-D Ca2+ dynamics phenomena, the location of calcium uptake and release microdomains on the endoplasmic reticulum, and the correlation between different calcium signals inside the cell. A perinuclear zone acting as a filter and regulator of intracellular calcium waves was detected: it acts as a controller of calcium fluxes between the cytoplasm and the nucleus.

Temporal and spatial analysis of astrocyte calcium waves

In the last decade new ideas were born about the temporal and spatial dynamics of intercellular calcium waves in astrocytes. In this paper we introduce a new approach to analyze the ways in which astrocytes communicate in cultures. We present a method to describe the spatial propagation of Ca2+ waves in vitro and a technique to compare the activity of different cells in vivo and in vitro under different stimulation conditions. The proposed method resulted to be an interesting way to distinguish different astrocyte clusters, which can be related to the communication characteristics in the network.

New Indices Extracted from Fetal Heart Rate Signal for the Assessment of Fetal Well-Being

In this paper, new parameters based on the Phase Rectified Signal Average (PRSA) of the Fetal Heart Rate (FHR) signal are introduced to assess fetal wellbeing. They are defined as the positive and negative slopes of the PRSA curve, namely Acceleration Phase Rectified Slope (APRS) and Deceleration Phase Rectified Slope (DPRS), depending on the sign of the slope. The parameters were computed on FHR time series recorded from 59 healthy and 61 Intra Uterine Growth Restricted (IUGR) fetuses, during CTG non-stress tests. The performance of APRS and DPRS was compared with the performance of other parameters extracted from the PRSA curve already existing in literature, and with other clinical indices that are provided by computerized cardiotocographic systems. The APRS and DPRS performed better than any other parameter considered in this study to distinguish between healthy and IUGR fetuses. We believe that these new indices might provide useful improvements of the quality of fetus early diagnosis.

Extraction of fetal heart rate from maternal surface ECG with provisions for multiple pregnancies

Twin pregnancies carry an inherently higher risk than singleton pregnancies due to the increased chances of uterine growth restriction. It is thus desirable to monitor the wellbeing of the fetuses during gestation to detect potentially harmful conditions. The detection of fetal heart rate from the maternal abdominal ECG represents one possible approach for noninvasive and continuous fetal monitoring. Here, we propose a new algorithm for the extraction of twin fetal heart rate signals from maternal abdominal ECG recordings. The algorithm detects the fetal QRS complexes and converts the QRS onset series into a binary signal that is then recursively scanned to separate the contributions from the two fetuses. The algorithm was tested on synthetic singleton and twin abdominal recordings. It achieved an average sensitivity and accuracy for QRS complex detection of 97.5% and 93.6%, respectively.