A Recurrence Plot Based Method for the Detection of End of T-Wave in Abnormal Non-Invasive Fetal Electrocardiogram Signals

Features of fetal electrocardiogram (fECG) can convey a lot of information about the function of the heart of the fetus. Up until now, there is little to no research that ad-dresses automatic detection techniques for non-invasive fECG (nfECG). This study discusses a detection technique based on recurrence plots to locate end of T-waves. Identification of the ending timings of T-waves is important to estimate ST and QT intervals. ST and QT intervals are good biomarkers for several cardiovascular diseases that include hypoxia and ischemia. The proposed technique was applied on nfECG records that included normal and abnormal cases. The proposed method could detect end of T-waves in most of the analyzed beats. Bland Altman plots of QT and QTc intervals show that at least 95% of the analyzed beats fall within the limits of agreement (LoA).