Component Analysis (ICA) to separate FECG from maternal ECG recordings measured on the maternal abdomen. And we also compared the results of ICA with the results of Principal Component Analysis (PCA) [3]. The aim of this article is to show the FECG after ICA and to identify the P wave, QRS complex, and T wave by using CWT. With large fluctuations, we used wavelet-based multiresolution analysis (MRA) to exclude those trends. We also used wavelet thresholding to remove noise.
PATIENTS AND METHODSMaternal and fetal ECG. It is almost impossible for the naked eye to recognize the admixture of the fetal ECG waveform in standard ECG leads from that of a pregnant woman. The signals were recorded from 8 skin electrodes with the wrist leads placed over the maternal abdomen on both sides of the uterine fundus, the left leg lead placed just above the pubic bone, and the remaining 4 leads placed orthogonally around the maternal abdomen. The ECG data are Japanese Journal of Physiology Vol. 54, No. 5, 2004 457 As with adults, the analysis of a fetal electrocardiogram (FECG) would be a reliable method for diagnosing cardiac diseases, especially fetal arrhythmias. During delivery, accurate recordings can be made by placing an electrode on the fetal scalp. However, other methods should be used during pregnancy because of the inaccessibility of the fetus. Ideally, recording FECG from the maternal abdomen is a highly desirable method. In our earlier report [1, 2], we detected FECG waveforms from ECG on the maternal abdomen by wavelet theory based methods. However, special situations frequently occur not only for the fetal QRS complex superimposed by the maternal QRS complex, but also for the fetal P wave and T wave in close vicinity to the maternal QRS complex. When superimposed by the maternal QRS complex, the fetal QRS cannot be visualized, and also when in close vicinity to the maternal QRS complex, the fetal P wave and T wave cannot be identified by the use of continuous wavelet transform (CWT). To resolve these problems, we resorted to Independent Japanese Journal of Physiology Vol. 54, [457][458][459][460][461][462][463] 2004 Received on February 27, 2004; accepted on October 13, 2004 Correspondence should be addressed to: Yasuhiro Ishikawa, Ishikawa Medical Clinic, 1-3-16 Honmachi-Nishi, Cyu-ou-ku, Saitama, 338-0004 Japan. Phone: +81-48-852-3123, Fax: +81-48-857-7481, E-mail: ishiyasu@uinet.or.jp, wavelet@nifty.ne.jp Abstract: Once the fetal electrocardiogram (FECG) waveforms from ECG on the maternal abdomen are detected, the fetal P wave and T wave cannot always be identified by using continuous wavelet transform (CWT). We took noninvasive FECG from the maternal abdomen, extracted it from the maternal electrocardiogram waveforms after an Independent Component Analysis (ICA), and identified the features of those waveforms by using CWT. We also simultaneously analyzed the observed signals by Primary Component Analysis (PCA). FECG has been extracted by ICA from 25 of 30 pregnant women. The fetal P wave and T wave could ...