Fetal electrocardiogram using signal-averaged electrocardiography

我们开发了使用单次平均心电图无创记录胎儿心电图的方法。首先，我们确定了信号平均心电图的最佳设置。胎儿心电图显示高频心动过速。建立了胎儿心电图与母亲低频信号噪声分离系统。采用模拟滤波器降低噪声，放大真实心电图分量。将这些数据转换为数字信号后，减去母体心电图，只保留胎儿心电图。为了获得更纯净的胎儿心电图，我们使用了几种资源。为了降低母亲的噪音，在她的腹部皮肤上使用Ag/AgCl电极和角质霜。低通滤波器的频率为2Hz，适合于降低胎儿运动和呼吸产生的伪影。产妇心电图减法时间设定为QRS波峰值±400 msec。近年来，采用了更灵敏的0.3 mV滤波器。临床可记录胎儿心律失常（室性早搏）和长QT综合征的心电图。特别是对于长QT综合征，此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.