Reconstruction of fetal vector electrocardiogram from maternal abdominal signals under fetus body rotations.

Fetal electrocardiogram (fECG) and its vector form (fVECG) could provide significant clinical information concerning physiological conditions of a fetus. So far various independent component analysis (ICA)-based methods for extracting fECG from maternal abdominal signals have been proposed. Because full extraction of component waves such as P, Q, R, S, and T, is difficult to be realized under noisy and nonstationary situations, the fVECG is further hard to be reconstructed, where different projections of the fetal heart vector are required. In order to reconstruct fVECG, we proposed a novel method for synthesizing different projections of the heart vector, making good use of the fetus movement. This method consists of ICA, estimation of rotation angles of fetus, and synthesis of projections of the heart vector. Through applications to the synthetic and actual data, our method is shown to precisely estimate rotation angle of the fetus and to successfully reconstruct the fVECG.

Robustness of the blind source separation with reference against uncertainties of the reference signals.

The fetal electrocardiogram (ECG) could provide clinical information concerning physiological conditions of the fetus. In order to extract fetal ECG, we proposed the novel algorithm, the blind source separation with reference (BSSR), which successfully extracts a complete waveform of QRS complex and avoids uncertainty in the order of the extracted signals. In the BSSR, the reference signal is supposed to be generated from the ultrasonic Doppler signal. Thus generated reference is expected to suffer from uncertainties in waveform and occurrence timing. Based on simulations, the BSSR is shown to have robustness against the uncertainties of reference signals. In addition, it is shown how the robustness depends on the order of power of correlation function between the reference and extracted signals, which composes a performance function of the BSSR.