Fetal electrocardiogram using signal-averaged electrocardiography

我们发展了一种无创记录胎儿心电图的方法--单平均心电图法。首先，我们确定了信号平均心电图仪的最佳设置。胎儿心电图示高频心动过速。建立了胎儿心电信号与母亲带噪声低频分量的分离系统。通过模拟滤波降低了噪声，放大了真实的心电成分。将这些数据转换为数字信号后，减去母体心电，仅保留胎儿心电。为了获得更纯净的胎儿心电图，对这几种资源进行了管理。为了减少母体噪声，在她的腹部皮肤上使用了银/氯化银电极和克雷汀乳膏。2赫兹的低通滤波适合于减少胎儿运动和呼吸引起的伪影。母体心电图减影时间设定为QRS波峰值±400毫秒。最近，使用了更灵敏的滤光片，0.3 mV。在临床环境下，可以记录到胎儿心律失常(室性早搏)和长QT综合征的心电图。特别是在长QT综合征中，这种方法对其出生后的诊断和处理非常有用。

We developed the method for non-invasive recording of fetal electrocardiogram using singal-averaged electrocardiography. At first, we determined the optimal setting for signal-averaged electrocardiography. Fetal electrocardiography shows tachycardia with high frequency. We established the system which separated fetal electrocardiography from mother's low frequent component with signal noise. The noise was decreased by using analog-filter, and true electrocardiographic components were amplified. After changing these data to digital-signal, maternal electrocardiography was subtracted, and only fetal electrocardiography kept remained. The several resources was administered in order to get more purified fetal electrocardiography. To decrease maternal noise, Ag/AgCl electrodes were used with keretin-cream on her abdominal skin. As a low pass filter of 2Hz was suitable for reducing artifact due to movement and respiration of fetus. Time duration for subtraction of maternal electrocardiography was set at the peak of her QRS wave ±400 msec. Recently, more sensitive filter with 0.3 mV was used.In clinical setting, electrocardiogram of fetal arrhyihmia (ventricular premature beat) and long QT syndrome could be recorded. Especially in long QT syndrome, this method is quite useful for its diagnosis and management after birth.