Evaluating the reliability of fetal electrocardiogram monitoring that acts via the abdominal wall of pregnant rabbits

A next generation fetal electrocardiogram (ECG) that can assess fetal well-being accurately is required in clinical settings. We developed a fetal ECG monitoring system that acts via the maternal abdominal wall and measured the ECG in our clinical studies. To assess the accuracy of the clinical fetal ECG monitoring records, it was necessary to confirm that the waveforms obtained by the indirect lead had the same accuracy as those by the direct lead. This study is translational research in which a murine fetal ECG system with the direct lead that we had already developed was applied and pregnant rabbits that had enough space to place electrodes on the maternal abdominal surface were used. In this study, fetal ECG was measured using the direct and indirect lead simultaneously using pregnant rabbits. The R-squared value between the RR-intervals obtained by the direct lead and those by the indirect lead of the same fetus was used to determine the reliability of the clinically developed fetal ECG monitoring system. The fetal ECG waveform, both with the direct and indirect lead, was obtained from three out of five pregnant rabbits. The average R-squared value was 0.99. Although one of the three pregnant rabbits presented with an atrioventricular block during the measurement, the fetal ECG waveform was successfully extracted with both the direct and indirect lead. The results of this study demonstrate that the fetal ECG monitoring system that acts via the maternal abdominal wall has the same accuracy as that of the direct lead.