Fetal Movement Counting Using Optical Fibre Sensors

Daily fetal movement counting based on maternal perception is widely deployed to monitor fetal wellbeing. However, the counting performed by the mother is prone to errors for various reasons. There are limited devices on the market that can provide reliable and automatic counting. This paper presents a prototype of a novel fetal movement monitoring device based on fibre Bragg grating sensors. Deformation of the skin caused by a fetal movement can lead to a change of the strain and stress on the optical fibre sensors, therefore can induce distortions to the breathing pattern of the mother. In the study data was gathered by the sensors through strain measurement and was post-processed using independent component analysis (ICA) and high-pass filtering to show the instances of the fetal movements. Information gathered during user trials with the prototype suggests that the system detects significantly higher numbers of fetus movements than that observed based on the mother’s perception. Among the various techniques available for fetal movement monitoring, fibre optic sensing provides many advantages including multiplex capability, flexibility and minimal size, making the concept an attractive solution for reliable monitoring of antenatal fetal movements

Minimizing discordances in automated classification of fractionated electrograms in human persistent atrial fibrillation

Ablation of persistent atrial fibrillation (persAF) targeting complex fractionated atrial electrograms (CFAEs) detected by automated algorithms has produced conflicting outcomes in previous electrophysiological studies. We hypothesize that the differences in these algorithms could lead to discordant CFAE classifications by the available mapping systems, giving rise to potential disparities in CFAE-guided ablation. This study reports the results of a head-to-head comparison of CFAE detection performed by NavX (St. Jude Medical) versus CARTO (Biosense Webster) on the same bipolar electrogram data (797 electrograms) from 18 persAF patients. We propose revised thresholds for both primary and complementary indices to minimize the differences in CFAE classification performed by either system. Using the default thresholds [NavX: CFEMean ≤ 120 ms; CARTO: ICL ≥ 7], NavX classified 70 % of the electrograms as CFAEs, while CARTO detected 36 % (Cohen’s kappa κ ≈ 0.3, P < 0.0001). Using revised thresholds found using receiver operating characteristic curves [NavX: CFE-Mean ≤ 84 ms, CFE-SD ≤ 47 ms; CARTO: ICL ≥ 4, ACI ≤ 82 ms, SCI ≤ 58 ms], NavX classified 45 %, while CARTO detected 42 % (κ ≈ 0.5, P < 0.0001). Our results show that CFAE target identification is dependent on the system and thresholds used by the electrophysiological study. The thresholds found in this work counterbalance the differences in automated CFAE classification performed by each system. This could facilitate comparisons of CFAE ablation outcomes guided by either NavX or CARTO in future works

An interactive platform to guide catheter ablation in human persistent atrial fibrillation using dominant frequency, organization and phase mapping

Background and Objective: Optimal targets for persistent atrial fibrillation (persAF) ablation are still debated. Atrial regions hosting high dominant frequency (HDF) are believed to participate in the initiation and maintenance of persAF and hence are potential targets for ablation, while rotor ablation has shown promising initial results. Currently, no commercially available system offers the capability to automatically identify both these phenomena. This paper describes an integrated 3D software platform combining the mapping of both frequency spectrum and phase from atrial electrograms (AEGs) to help guide persAF ablation in clinical cardiac electrophysiological studies. Methods: 30 s of 2048 non-contact AEGs (EnSite Array, St. Jude Medical) were collected and analyzed per patient. After QRST removal, the AEGs were divided into 4 s windows with a 50% overlap. Fast Fourier transform was used for DF identification. HDF areas were identified as the maximum DF to 0.25 Hz below that, and their centers of gravity (CGs) were used to track their spatiotemporal movement. Spectral organization measurements were estimated. Hilbert transform was used to calculate instantaneous phase. Results: The system was successfully used to guide catheter ablation for 10 persAF patients. The mean processing time was 10.4 ± 1.5 min, which is adequate comparing to the normal electrophysiological (EP) procedure time (120∼180 min). Conclusions: A customized software platform capable of measuring different forms of spatiotemporal AEG analysis was implemented and used in clinical environment to guide persAF ablation. The modular nature of the platform will help electrophysiological studies in understanding of the underlying AF mechanisms

Continuous speech with pauses inserted between words increases cortical tracking of speech envelope

The decoding multivariate Temporal Response Function (decoder) or speech envelope reconstruction approach is a well-known tool for assessing the cortical tracking of speech envelope. It is used to analyse the correlation between the speech stimulus and the neural response. It is known that auditory late responses are enhanced with longer gaps between stimuli, but it is not clear if this applies to the decoder, and whether the addition of gaps/pauses in continuous speech could be used to increase the envelope reconstruction accuracy. We investigated this in normal hearing participants who listened to continuous speech with no added pauses (natural speech), and then with short (250 ms) or long (500 ms) silent pauses inserted between each word. The total duration for continuous speech stimulus with no, short, and long pauses were approximately, 10 minutes, 16 minutes, and 21 minutes, respectively. EEG and speech envelope were simultaneously acquired and then filtered into delta (1–4 Hz) and theta (4–8 Hz) frequency bands. In addition to analysing responses to the whole speech envelope, speech envelope was also segmented to focus response analysis on onset and non-onset regions of speech separately.Our results show that continuous speech with additional pauses inserted between words significantly increases the speech envelope reconstruction correlations compared to using natural speech, in both the delta and theta frequency bands. It also appears that these increase in speech envelope reconstruction are dominated by the onset regions in the speech envelope.Introducing pauses in speech stimuli has potential clinical benefit for increasing auditory evoked response detectability, though with the disadvantage of speech sounding less natural. The strong effect of pauses and onsets on the decoder should be considered when comparing results from 3 different speech corpora. Whether the increased cortical response, when longer pauses are introduced, reflect improved intelligibility requires further investigation

Dataset for: Hearing aids do not alter cortical entrainment to speech at audible levels in mild-to-moderately hearing-impaired subjects

Dataset supports: Vanheusden, Frederique Jos et al. (2019). Hearing aids do not alter cortical entrainment to speech at audible levels in mild-to-moderately hearing-impaired subjects. Frontiers in Human Neuroscience</span

Development of Reduced-Lead Body Surface Mapping Systems Using Spatial Frequency Analysis

•Body Surface Maps (BSMs) are starting to be used in clinic. •An enormous amount of data is obtained, which can be cumbersome to handle. Reduction of data can significantly decrease analysis time. •Here, the minimum number of electrodes necessary to reconstruct BSM maps accurately is determined by Lomb-Scargle spatial frequency analysis (LSSA) and singular value decomposition (SVD). [Taken from the Introduction

Characterization of Density of High Dominant Frequency Sites in Persistent Atrial Fibrillation Patients

Characterization of Density of High Dominant Frequency Sites in Persistent Atrial Fibrillation Patient

Contributing Factors Concerning Inconsistencies in Persistent Atrial Fibrillation Ablation Outcomes

Abstract In the present work, we investigated current methods for complex fractionated atrial electrogram (CFAE

A Platform to guide Catheter Ablation of Persistent Atrial Fibrillation using Dominant Frequency Mapping

Introduction: Dominant frequency (DF) analysis has been widely used to understand the pathophysiology of atrial fibrillation (AF). An interactive digital platform was developed to provide real-time DF mapping during DF-guided AF ablation. Methods: A user oriented graphic interface was developed in Matlab for real-time analysis of data exported from the non-contact balloon array (St. Jude Ensite Velocity System). The platform performs QRST subtraction on all electrograms (EGM) and Fast Fourier transform with 4 seconds windows (50% overlap) to compute DF, organization index (OI), regularity index (RI) and phase. DF, OI and RI of each window can be colour-coded and plotted on a 3D left atrium mesh, and 3D phase movies can also be played using a slider. High DF areas and the trajectory of their centres of gravity can be shown per individual window. Also any EGM of interest on the 3D mesh is easily accessible using the mouse. Results: 30 seconds of EGM data sampled at 2034.5 Hz with 2048 chan-nels are processed within 10 mins, which is acceptable for practical use dur-ing catheter ablation. The figure shows the percentage of processing time of each part of the program. Till now the software was tested and used success-fully in 5 catheter ablation cases. Conclusion: The proposed platform is fully automated with user-oriented graphic interface that provides a 3 dimensional representation of the left atrium with the DF behaviour. This software might provide further online information to relate DF to remodelled atrial substrate