Systematic methods for fetal electrocardiographic analysis: Determining the fetal heart rate, RR interval and QT interval

Non-invasive fetal electrocardiographic (FECG) monitoring plays an important role for detecting and diagnosing the fetal diseases due to its negligible risk. In the present study, we aimed to propose systematic methods for accurately locating the fetal QRS complexes and estimating the QT interval in non-invasive FECG signals. The methods included 4 steps. In Step 1, we firstly used the wavelet decomposition and comb notching filter to pre-process the original maternal abdominal ECG (AECG). Then we used the entropy method to assess the signal quality. Finally principal component analysis (PCA) and signal quality flags were used to obtain an optimal AECG reference signal for maternal R-peaks detection. Step 2 determined the actual maternal R-peaks for the channels with good signal quality. In Step 3, maternal ECG (MECG) templates were constructed using the coherent averaging method and the constructed MECG signals were obtained by first compressing the MECG template according to the real length of each period and then joining period-by-period. The pure FECG signals from the channels with good signal quality were obtained by removing the corresponding MECG signals. In Step 4, after the pre-processing for the obtained FECG signals, fetal R-peaks were determined by a combination method of adaptive threshold and PCA and then fetal heart rate, fetal RR and QT intervals were determined. Our best entry results on set B were: average score for event 4 is 264.87 and average score for event 5 is 9.04, which is a significant improvement compared with the sample submission (event 1/4 is 3258.56 and event 2/5 is 102.75).