基于扩展卡尔曼滤波和奇异值分解算法的单通道胎儿心电提取方法

提出一种将扩展卡尔曼滤波(EKF)算法和奇异值分解(SVD)算法相结合的单通道胎儿心电提取方法。首先,建立母体心电的动态模型,利用该模型通过扩展卡尔曼滤波或扩展卡尔曼平滑(EKS),从孕妇的单通道腹部信号中估计出母体心电成分,然后与单通道腹部信号相减得到胎儿心电信号的初步估计,随后再利用奇异值分解算法,对初步估计出的胎儿心电信号进行去噪处理,以期得到高信噪比的胎儿心电信号。另外,针对胎儿心律不齐的情况,在奇异值分解算法中提出一种改进的心电信号重构矩阵构造方法。对合成腹部信号和实际腹部信号(源于DaISy数据库和PhysioNet中的非侵入式胎儿心电数据库,共计49个腹部通道的数据),进行胎儿心电提取实验。结果表明,使用EKF+SVD或EKS+SVD的算法比单独使用EKF或EKS的算法,提取出的胎儿心电信号的信噪比提高约5 dB,胎儿心电提取的准确性分别达95.60%和95.94%。结合EKF和SVD算法的单通道胎儿心电提取方法,可以有效地提高胎儿心电信号的信噪比和提取的准确性,并且适用于母体或胎儿心律不齐的情况。

Fetal ECG Extraction from Single-Channel Abdominal ECG Based on EKF Combined with SVD

In this paper, an approach based on extended Kalman filtering (EKF) combined with singular value decomposition (SVD) was proposed to extract fetal electrocardiogram (fECG) from single-channel abdominal ECG recording. First, on the basis of the dynamic model of maternal electrocardiogram established, the maternal ECG component was estimated from the single-channel abdominal signal by EKF or extended Kalman smoothing (EKS). Next, the preliminary estimation of fetal ECG was obtained by subtracting the maternal ECG component from the single-channel abdominal signal. To obtain the fetal ECG with high signal-to-noise ratio, the preliminary fetal ECG was denoised using SVD. In addition, an improved construction method of the ECG signal reconstruction matrix was proposed in the SVD algorithm for the case of fetal arrhythmia. Synthetic abdominal signals and real abdominal signals (49 abdominal channels in total from DaISy database and PhysioNet non-invasive fetal ECG database) were used for fetal ECG extraction. The results showed that the signal-to-noise ratio of fetal ECG extracted by EKF+SVD or EKS+SVD was about 5 dB higher than that by EKF or EKS alone, and the accuracy of fetal ECG extraction was 95.60% and 95.94%, respectively. In conclusion, the single-channel fetal ECG extraction method based on the combination of EKF and SVD could effectively improve the signal-to-noise ratio and accuracy of fetal ECG signals extraction, and would be suitable for maternal or fetal arrhythmia.