Sato Michiyoshi, Kimura Yoshitaka, Chida Shinichi, Ito Takuya, Katayama Norihiro, Okamura Kunihiro, Nakao Mitsuyuki
Graduate School of Information Sciences, Tohoku University, Sendai 980-8575, Japan.
IEEE Trans Biomed Eng. 2007 Jan;54(1):49-58. doi: 10.1109/TBME.2006.883791.
In contrast to the ultrasonic measurement of fetal heart motion, the fetal electrocardiogram (ECG) provides clinically significant information concerning the electrophysiological state of a fetus. In this paper, a novel method for extracting the fetal ECG from abdominal composite signals is proposed. This method consists of the cancellation of the mother's ECG and blind source separation with the reference signal (BSSR). The cancellation of the mother's ECG component was performed by subtracting the linear combination of mutually orthogonal projections of the heart vector. The BSSR is a fixed-point algorithm, the Lagrange function of which includes the higher order cross-correlation between the extracted signal and the reference signal as the cost term rather than a constraint. This realizes the convexity of the Lagrange function in a simple form, which guarantees the convergence of the algorithm. By practical application, the proposed method has been shown to be able to extract the P and T waves in addition to the R wave. The reliability and accuracy of the proposed method was confirmed by comparing the extracted signals with the directly recorded ECG at the second stage of labor. The gestational age-dependency of the physiological parameters of the extracted fetal ECG also coincided well with that of the magnetocardiogram, which proves the clinical applicability of the proposed method.
与胎儿心脏运动的超声测量不同，胎儿心电图（ECG）提供了有关胎儿电生理状态的临床重要信息。本文提出了一种从腹部复合信号中提取胎儿心电图的新方法。该方法包括消除母亲的心电图和利用参考信号进行盲源分离（BSSR）。通过减去心脏向量相互正交投影的线性组合来消除母亲的心电图成分。BSSR是一种定点算法，其拉格朗日函数将提取信号与参考信号之间的高阶互相关作为代价项而非约束条件。这以简单的形式实现了拉格朗日函数的凸性，保证了算法的收敛性。通过实际应用表明，该方法除了能提取R波外，还能提取P波和T波。通过将提取的信号与分娩第二阶段直接记录的心电图进行比较，证实了该方法的可靠性和准确性。提取的胎儿心电图生理参数的孕周依赖性也与心磁图的依赖性非常吻合，这证明了该方法的临床适用性。
