Current Development in Theory and Applications of Wavelets
Volume 3, Issue 2, Pages 169 - 192
(August 2009)
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TIME-FREQUENCY ANALYSIS OF CTG SIGNALS
M. Romano (Italy), M. Cesarelli (Italy), P. Bifulco (Italy), M. Ruffo (Italy), A. Fratini (Italy) and G. Pasquariello (Italy)
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Abstract:
Monitoring foetal health is a very important task in clinical practice to appropriately plan pregnancy management and delivery. In the third trimester of pregnancy, cardiotocography (CTG) is the most employed diagnostic technique. In CTG monitoring, foetal heart rate (FHR) and uterine contractions (UC) signals are simultaneously recorded and analysed in order to ascertain foetal health. In particular, indexes related to variability of FHR (FHRV) are usually utilised, which enrich information provided by CTG. FHRV is acknowledged as an important parameter for the evaluation of foetal well-being. Moreover, HR fluctuations analysis allows for a non-invasive estimation of both the sympathetic and parasympathetic branches of the autonomic nervous system (ANS). Hence, one can observe all of the FHRV frequency components and their modifications by applying a time-frequency approach. Time dependent spectrum analysis, in fact, allows for a distinct understanding of the spectral components during dynamic or active foetal states and their change over time. This work aims to show some specific very useful examples of FHRV time-frequency analysis purposes. Furthermore, the necessity of a data pre-processing before FHRV signal processing is considered here. Obtained results showed important modifications of power spectral density (PSD) correlated to different foetal conditions. Hence they confirmed that FHRV provides extremely significant information concerning the cardiac and ANS activities. Our results showed also that some important clinical parameters related to PSD of FHRV (such as sympatho-vagal balance) can be erroneously estimated due to a not appropriate storage rate of CTG data. |
| Keywords and phrases: cardiotocography, time-frequency analysis, FHRV. |
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