12 research outputs found
Mapování elektrických potenciálů z povrchu hrudníku - předzpracování a vizualizace
The aim of the paper is to present current research activity in the area of computer supported ECG processing.
Analysis of heart electric field based on standard 12lead system is at present the most frequently used method of heart disease
diagnostics. However body surface potential mapping (BSPM) that measures electric potentials from several tens to hundreds
of electrodes placed on thorax surface has in certain cases higher diagnostic value given by data collection in areas that are
inaccessible for standard 12lead ECG. For preprocessing, wavelet transform is used; it allows detect significant values on the
ECG signal. Several types of maps, namely immediate potential, integral, isochronous, and differential
Fractal Analysis and Hurst Parameter for Intrapartum Fetal Heart Rate Variability Analysis: A Versatile Alternative to Frequency Bands and LF/HF Ratio
International audienceBackgroun
Investigating pH based evaluation of fetal heart rate (FHR) recordings
Cardiotocography (CTG) is a standard tool for the assessment of fetal well-being during pregnancy and delivery. However, its interpretation is associated with high inter- and intra-observer variability. Since its introduction there have been numerous attempts to develop computerized systems assisting the evaluation of the CTG recording. Nevertheless these systems are still hardly used in a delivery ward. Two main approaches to computerized evaluation are encountered in the literature; the first one emulates existing guidelines, while the second one is more of a data-driven approach using signal processing and computational methods. The latter employs preprocessing, feature extraction/selection and a classifier that discriminates between two or more classes/conditions. These classes are often formed using the umbilical cord artery pH value measured after delivery. In this work an approach to Fetal Heart Rate (FHR) classification using pH is presented that could serve as a benchmark for reporting results on the unique open-access CTU-UHB CTG database, the largest and the only freely available database of this kind. The overall results using a very small number of features and a Least Squares Support Vector Machine (LS-SVM) classifier, are in accordance to the ones encountered in the literature and outperform the results of a baseline classification scheme proving the utility of using advanced data processing methods. Therefore the achieved results can be used as a benchmark for future research involving more informative features and/or better classification algorithms.Validerad;2017;Nivå 2;2017-12-05 (rokbeg)</p
Wavelet coefficients, Wavelet Spectrum and Hurst Parameter.
<p>Wavelet coefficients, Wavelet Spectrum and Hurst Parameter.</p
ROC curves.
<p>for </p><p></p><p></p><p></p><p></p><p><mi>H</mi><mo>^</mo></p><p><mn>0</mn><mo>.</mo><mn>04</mn><mo>−</mo><mn>0</mn><mo>.</mo><mn>40</mn></p><p></p><p></p><p></p><p></p> superimposed to that obtained from LF/HF<sub>0.15</sub> are found to yield equivalent performance while the former avoids the recourse to the arbitrary and irrelevant choice of the intermediate frequency <i>f</i><sub><i>interm</i></sub> = 0.15Hz.<p></p
Fetal heart rate BpM time series PSD.
<p>From left to right, BpM time series, Fourier spectrum (or Power Spectral Density) and Wavelet Spectrum (Logscale Diagram (LD)), From top to bottom, example from the Index group, example from the Control group with abnormal fetal heart rate, example from the Control group with normal fetal heart rate. The power-law shaped Fourier and wavelet spectra indicate fractal dynamics, rather than frequency band-type dynamics.</p
ROC curves for LF/HF ratios.
<p>ROC curve for representative LF/HF<sub><i>f</i><sub><i>interm</i></sub></sub> ratios computed from ranges LF = [0.04, <i>f</i><sub><i>interm</i></sub>], HF = [<i>f</i><sub><i>interm</i></sub>, 0.40] with different intermediate frequencies <i>f</i><sub><i>interm</i></sub>. The classical adult bands, <i>f</i><sub><i>interm</i></sub> = 0.15Hz corresponds to the dark black solid line.</p