基于小波变换的心电信号降噪处理

实测的心电信号不可避免地存在一些强干扰和噪声,为了实现准确地提取反映心电信号的特征信息,该文应用一维离散小波变换实现了对心电信号的降噪处理。实验研究结果表明,该方法能够有效地去除心电信号中的噪声,从而为心电信号特征信息的提取奠定了理论基础。     

基于AD8232的心电实时监测及分析系统设计

为了方便对患者心电信号进行实时监测,实现对心脏疾病的及时预防及诊断,利用一款基于ATmega328p微控制器的Arduino开发板、一块心电监测前端模块AD8232及上位机软件LabVIEW开发出一套心电实时监测系统,并利用LabVIEW设计出多种软件滤波方法来抑制心电信号中的噪声。由于心电信号的时频特性能提供反映患者心脏活动动态行为的信息,该系统还包括基于LabVIEW设计出的多种用于心电信号实时分析的程序,使被试心电信号所包含的生理特性能够及时地被分析出来。利用所开发的心电实时监测分析系统对被试的心电信号进行采集和分析,发现系统能够非常灵敏、准确地检测心电信号,并对信号噪声有着很好的抑制能力。此外系统能够对信号进行各式的实时分析,且分析结果可靠,能够运用于临床诊断。利用该系统对心电信号进行实时采集和分析,其测量结果准确、去噪效果良好、分析结果可靠,为今后心电实时监测分析系统的设计提供了借鉴。     

无线数传技术在远程心电监护系统中的应用

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WebECG: A novel ECG simulator based on MATLAB Web Figure

Electrocardiogram is a signal containing information about the condition and operation of heart. Nowadays, many heart diseases can be efficiently diagnosed using these signals. However, a proper recognition and classification of the heart signals are essential requirement for the diagnosis of heart diseases. In this study, emphasizing on this requirement, a new ECG simulator based on MATLAB Web Figure called WebECG is designed and implemented to facilitate the education on ECG signals. Advanced flexibility and good visualization capabilities including 3-dimension view, zoom and move on ECG graphics are provided by WebECG. The users are able to plot ECG signals with different parameters, to plot the ECGs of nine arrhythmia types. Furthermore, WebECG is capable to add three different noises to ECG and to plot/analyze long-term ECGs. These properties of the WebECG support efficient web-based education of ECG signals.     

无线数传技术在远程心电监护系统中的应用

心脏病是严重威胁人类健康和生命的主要疾病之一.现有的远程心电监护系统存在难以充分释放医院的专业资源、服务范围有限等不足,将心电监护从医院扩展到家庭,实现远程监护具有非常重要的现实意义.本文讨论了利用无线数传技术实现远程心电数据采集的解决方案,使用PTR2000无线通信模块设计了便携式心电数据采集发送盒和心电数据接收转发器,实现了对病人心电数据的远程采集和传输,为通过宽带网实现病人心电数据的远程采集和传输创造了条件.     

人体HRV信号的检测及其最大李雅普诺夫指数估算

介绍了一种便携式心电监测仪器,用于监测人心电(ECG)信号.根据获得的心电信号数据,采用小波变换技术进行心电R峰的准确定位,进而得到心率变异(Heart Rate Variability,HRV)信号序列.在对HRV信号进行相空间重构的基础上进行关联维、最大李雅普诺夫指数的估算.结果表明,健康者和心率不齐者的HRV信号的最大李雅普诺夫指数均为正值,但处于心率不齐状态HRV的最大李雅普诺夫指数低于健康状态的最大李雅普诺夫指数.     

A comparative analysis of principal component and independent component techniques for electrocardiograms

Principal component analysis (PCA) is used for ECG data compression, denoising and decorrelation of noisy and useful ECG components or signals. In this study, a comparative analysis of independent component analysis (ICA) and PCA for correction of ECG signals is carried out by removing noise and artifacts from various raw ECG data sets. PCA and ICA scatter plots of various chest and augmented ECG leads and their combinations are plotted to examine the varying orientations of the heart signal. In order to qualitatively illustrate the recovery of the shape of the ECG signals with high fidelity using ICA, corrected source signals and extracted independent components are plotted. In this analysis, it is also investigated if difference between the two kurtosis coefficients is positive than on each of the respective channels and if we get a super-Gaussian signal, or a sub-Gaussian signal. The efficacy of the combined PCA–ICA algorithm is verified on six channels V1, V3, V6, AF, AR and AL of 12-channel ECG data. ICA has been utilized for identifying and for removing noise and artifacts from the ECG signals. ECG signals are further corrected by using statistical measures after ICA processing. PCA scatter plots of various ECG leads give different orientations of the same heart information when considered for different combinations of leads by quadrant analysis. The PCA results have been also obtained for different combinations of ECG leads to find correlations between them and demonstrate that there is significant improvement in signal quality, i.e., signal-to-noise ratio is improved. In this paper, the noise sensitivity, specificity and accuracy of the PCA method is evaluated by examining the effect of noise, base-line wander and their combinations on the characteristics of ECG for classification of true and false peaks.     

基于STM32便携式心电监护装置的设计

综合运用传感器技术、嵌入式技术和无线通信技术,设计了一种以STM32F103C8T6微处理器为核心的家用便携式心电监护装置.利用Pulse Sensor脉搏心率传感器采集心电信号,经STM32内置的模数转换器(ADC)处理得到数字信号.LCD屏用于实时显示心率值和心电图(ECG),心率数据通过蓝牙通信模块实时传输到手机...     

自适应小波尺度谱阈值在膈肌信号降噪的应用

膈肌肌电信号是人体微弱的生物电信号,此信号常受到心电信号的严重干扰。为了提高阈值在膈肌肌电信号降噪的准确度,提出了一种小波尺度谱阈值自适应的降噪算法。该算法先对膈肌肌电信号进行小波变换,再把小波系数转化为小波尺度谱,然后确定心电干扰位置,并且根据心电邻域小波能量自动调整阈值从而去除心电干扰。通过对膈肌肌电信号进行实验分析,并且与小波阈值方法进行对比,结果表明该方法降低了心电干扰并且保留了膈肌肌电信号的特征。     

Detection of electrocardiogram beats using a fuzzy similarity index

Abstract: A new approach based on the computation of a fuzzy similarity index (FSI) is presented for the detection of electrocardiogram (ECG) beats. Four types of ECG beats (normal beat, congestive heart failure beat, ventricular tachyarrhythmia beat, atrial fibrillation beat) obtained from the Physiobank database were analysed. The ECG signals were decomposed into time–frequency representations using the discrete wavelet transform and wavelet coefficients were calculated to represent the signals. The aim of the study is detection of ECG beats by the combination of wavelet coefficients and the FSI. Toward achieving this aim, fuzzy sets were obtained from the feature sets (wavelet coefficients) of the signals under study. The results demonstrated that the similarity between the fuzzy sets of the studied signals indicated the variabilities in the ECG signals. Thus, the FSI could discriminate the normal beat and the other three types of beats (congestive heart failure beat, ventricular tachyarrhythmia beat, atrial fibrillation beat).     

基于DSP的EASI十二导联多功能Holter系统

一种以数字信号处理器(DSP)为核心,具有实时检测、无线传输和24小时心电数据连续记录功能的多功能Holter系统。在该系统中,通过EASI导联系统模块采集心电信号,然后采用小波变换算法对心电信号进行实时特征提取,并将心电数据存入MicroSD卡实现24小时心电数据记录;或者通过Zigbee无线传输模块将心电数据传输到电脑进行远程实时监测及十二导联心电数据的推导。     

一种改进的心电信号基线漂移矫正方法

传统滑动平均滤波法有实现容易、计算简单的优点,但在矫正心电信号的基线漂移时容易造成有用心电信号的丢失,从而使滤波后的心电信号产生失真.文中在传统滑动滤波器的基础上,考虑心电数据的采样率并进行跳跃采样对算法进行改进,给出了改进算法的数学模型,并利用MIT-BIH心电数据库中的实测数据对两种算法进行了比较验证.实验表明改进算法处理后得到的结果,在矫正心电信号的基线漂移时与原算法相比,减少了有用心电信号的损失,滤波后的心电信号失真更小,与原始数据的吻合度更高,效果更理想.     

Motion artifact removal based on periodical property for ECG monitoring with wearable systems

Motion artifact removal (MR) is one of the essential issues in processing raw ECG signals since it could not be simply solved by using classic filtering. In this paper, a QRS detection based Motion Artifact Removal algorithm (QRSMR) is proposed. The proposed method detects the entire QRS complex and removes the noise between two QRS complexes, while recovering P and T-waves. As verified in the tests on simulated noisy ECG signals, QRSMR outputs with seriously contaminated ECG signals have an increase of the correlation with their original clean signals from 40% to nearly 80%, demonstrating the improved noise removal ability of QRSMR. Moreover, in the tests on real ECG signals measured on volunteers with a flexible wearable ECG monitoring device developed at Fudan University, QRSMR is able to recover P-wave and T-wave from the contaminated signal, which shows its enhanced performance on motion artifact reduction comparing with adaptive filtering method and other methods based only on empirical mode decomposition.     

基于改进FastICA的胎儿心电提取算法研究

针对FastICA算法容易陷入局部最优,导致提取的胎儿心电往往含有较多噪声的问题.本文将修正BFGS法(MB?FGS)和混沌优化算法相结合来代替传统的牛顿迭代法,提出一种新的独立分量分析方法,并用于胎儿心电信号的提取.分别用合成信号和临床信号对该算法进行验证,实验结果表明本文提出的算法能提取出清晰并不含母体心电的胎儿心电信号,而且算法性能更优于FastICA.     

非线性格兰杰因果关系在睡眠生理信号分析中的应用

基于非线性格兰杰因果关系分析睡眠生理信号。分别使用多项式核函数、高斯核函数和Sigmoid核函数将低维空间数据映射到高维特征空间,在高维特征空间使用非线性格兰杰因果方法来分析睡眠生理信号。研究结果表明,脑电信号对心电信号的影响比心电信号对脑电信号的影响更为显著,脑电信号对血压信号的影响比血压信号对脑电信号的影响更为显著,血压对心电信号的影响比心电信号对血压信号的影响更为显著,而且睡眠期样本信号间的格兰杰因果关系更为显著。仿真结果验证了睡眠期信号更能客观地反映生理信号的因果关系。     

Detecting variabilities of ECG signals by Lyapunov exponents

An approach based on the consideration that electrocardiogram (ECG) signals are chaotic signals was presented for automated diagnosis of electrocardiographic changes. This consideration was tested successfully using the nonlinear dynamics tools, like the computation of Lyapunov exponents. Multilayer perceptron neural network (MLPNN) architectures were formulated and used as basis for detection of variabilities of ECG signals. Four types of ECG beats (normal beat, congestive heart failure beat, ventricular tachyarrhythmia beat, atrial fibrillation beat) obtained from the Physiobank database were classified. The computed Lyapunov exponents of the ECG signals were used as inputs of the MLPNNs trained with backpropagation, delta-bar-delta, extended delta-bar-delta, quick propagation, and Levenberg–Marquardt algorithms. The performances of the MLPNN classifiers were evaluated in terms of classification accuracies. The results confirmed that the MLPNN trained with the Levenberg–Marquardt algorithm has potential in detecting the variabilities of the ECG signals (total classification accuracy was 95.00%).     

Discriminant analysis of multivariate time series: Application to diagnosis based on ECG signals

In analysing ECG data, the main aim is to differentiate between the signal patterns of healthy subjects and those of individuals with specific heart conditions. We propose an approach for classifying multivariate ECG signals based on discriminant and wavelet analyses. For this purpose we use multiple-scale wavelet variances and wavelet correlations to distinguish between the patterns of multivariate ECG signals based on the variability of the individual components of each ECG signal and on the relationships between every pair of these components. Using the results of other ECG classification studies in the literature as references, we demonstrate that our approach applied to 12-lead ECG signals from a particular database compares favourably. We also demonstrate with real and synthetic ECG data that our approach to classifying multivariate time series out-performs other well-known approaches for classifying multivariate time series.     

Syntactic recognition of ECG signals by attributed finite automata

A syntactic pattern recognition method of electrocardiograms (ECG) is described in which attributed automata are used to execute the analysis of ECG signals. An ECG signal is first encoded into a string of primitives and then attributed automata are used to analyse the string. We have found that we can perform fast and reliable analysis of ECG signals by attributed automata.     

Statistics over features of ECG signals

This paper presented the usage of statistics over the set of the features representing the electrocardiogram (ECG) signals. Since classification is more accurate when the pattern is simplified through representation by important features, feature extraction and selection play an important role in classifying systems such as neural networks. Multilayer perceptron neural network (MLPNN) architectures were formulated and used as basis for detection of variabilities of the ECG signals. Four types of ECG beats (normal beat, congestive heart failure beat, ventricular tachyarrhythmia beat, atrial fibrillation beat) obtained from the Physiobank database were classified. The selected Lyapunov exponents, wavelet coefficients and the power levels of power spectral density (PSD) values obtained by eigenvector methods of the ECG signals were used as inputs of the MLPNN trained with Levenberg–Marquardt algorithm. The classification results confirmed that the proposed MLPNN has potential in detecting the variabilities of the ECG signals.     

基于R峰配准重构的弱胎心电盲分离方法

利用盲分离技术从母亲腹心电中分离出胎心电在胎心电幅度较强的情况下是可行的,但如果胎心电过弱,盲分离中容易将胎心电视作噪声而无法正确分离.在胎心电过弱时,先对腹心电进行形态学滤波后检测胎心电的R峰,然后在配准胎儿R峰的前提下,平移、叠加并重构信号,最后对重构信号应用盲分离方法分离出较好的胎心电信号.实验证明,当胎心电微弱,直接盲分离容易将胎心电作为噪声而无法得到有效胎心电时,R峰配准重构可以有效地增强胎心电的信号强度,对重构后的信号进行盲分离可得到有效的胎心电,进而得到较精确的胎心率.