産業医学および健康問題

抽象的な

Systolic Fetal Heart Murmur Detected in Fetal Phonocardiography

Kazuo Maeda and Hitoo Nakano

Although clear fetal heart tones were auscultated with high-pitched tones, a sinusoidal fetal heart rate (FHR) was unable to be diagnosed, thus it was concluded that no fetal heart tone auscultation was suitable for the fetal monitoring. Fetal heart systolic period was stable and the diastolic duration varied when the FHR changed. FHR curve was traced with the triggers formed by single negative signal from the two tones of heart sound in the instantaneous FHR meter, of which microphone touching noise in FHR curve was prevented using autocorrelation heart rate meter, which made the automatic computerized FHR diagnosis successful. Fetal phonocardiography (fPCG) was studied by the tracing of fetal heart tones with the high-pass and low-cut frequency character. The oscilloscopic image recorded on a photographic film and the ink-writing record with slow-down tape technique using a data recorder achieved the recognition of high frequency component of fetal heart sound. The fetal heart tones of 105 normal pregnancies were studied and diamond shaped 100-200 Hz systolic murmur was recorded in 16.8% of the cases, which was not recorded and no cardiac abnormality was realized in the neonates after birth. Continuous wave ultrasonic record did not realize the murmur, therefore, the murmur was considered physiologically developed by the blood flow of fetal ductus arteriosus limitedly in antenatal life.