ECG waveform analysis by significant point extraction. II. Pattern matching

From a set of significant points which characterizes the ECG waveform, the pattern matching algorithm detects and classifies QRS complexes. R waves are detected from the analysis of global curvature. Next, the morphology of the QRS complex is determined. QRS complexes with different morphologies are classified by a correlation algorithm. This method is sensitive to changes in shape, such as that of abnormal QRS complexes. The algorithm should be useful in automated analysis of waveforms, such as ECG signals recorded in clinical environments.     

Kernel-based nonlinear dimensionality reduction for electrocardiogram recognition

The human heart is a complex system that reveals many clues about its condition in its electrocardiogram (ECG) signal, and ECG supervising is the most important and efficient way of preventing heart attacks. ECG analysis and recognition are both important and tempting topics in modern medical research. The purpose of this paper is to develop an algorithm which investigates kernel method, locally linear embedding (LLE), principal component analysis (PCA), and support vector machine(SVM) algorithms for dimensionality reduction, features extraction, and classification for recognizing and classifying the given ECG signals. In order to do so, a nonlinear dimensionality reduction kernel method based LLE is proposed to reduce the high dimensions of the variational ECG signals, and the principal characteristics of the signals are extracted from the original database by means of the PCA, each signal representing a single and complete heart beat. SVM method is applied to classify the ECG data into several categories of heart diseases. Experimental results obtained demonstrated that the performance of the proposed method was similar and sometimes better when compared to other ECG recognition techniques, thus indicating a viable and accurate technique.     

Using SEEK for multichannel pattern recognition

The author's work on computerized analysis of the 2-channel, 24-hr electrocardiogram has previously resulted in the development of multichannel signal processing systems that learn by observation. A new tool for implementing such algorithms is described: the pattern recognition language SEEK. Programs written in SEEK build a knowledge base containing treelike data structures, each of which stores acquired information about a particular multichannel waveform. Input data are interpreted by performing an efficient parallel evaluation of the structures in the knowledge base. The work is applicable to a wide variety of pattern recognition problems that arise in medical signal processing. The approach is illustrated with examples drawn from ECG analysis.     

基于小波变换和粗糙集的早搏信号识别算法

心电特征参数的选择和提取是心电图(ECG)分析的基础,提升检测算法的识别率和特征分类的精度是自动分析技术的关键。提出了基于小波变换和属性约简的心电早搏信号识别算法。该算法首先依据心血管专家的诊断标准选择了12个心电特征参数;然后运用基于小波变换的特征检测算法进行了特征提取,并利用基于粒计算的属性约简算法对特征参数进行了属性约简;最后,将约简后的数据用于模式分类并通过MIT-BIH数据库对结果进行验证。实验表明,约简后的分类精度大大高于约简前的数据,特征参数的合理选择(约简)是提高识别效率的重要因素。     

ECG biometric authentication based on non-fiducial approach using kernel methods

Identity recognition faces several challenges especially in extracting an individual's unique features from biometric modalities and pattern classifications. Electrocardiogram (ECG) waveforms, for instance, have unique identity properties for human recognition, and their signals are not periodic. At present, in order to generate a significant ECG feature set, non-fiducial methodologies based on an autocorrelation (AC) in conjunction with linear dimension reduction methods are used. This paper proposes a new non-fiducial framework for ECG biometric verification using kernel methods to reduce both high autocorrelation vectors' dimensionality and recognition system after denoising signals of 52 subjects with Discrete Wavelet Transform (DWT). The effects of different dimensionality reduction techniques for use in feature extraction were investigated to evaluate verification performance rates of a multi-class Support Vector Machine (SVM) with the One-Against-All (OAA) approach. The experimental results demonstrated higher test recognition rates of Gaussian OAA SVMs on random unknown ECG data sets with the use of the Kernel Principal Component Analysis (KPCA) as compared to the use of the Linear Discriminant Analysis (LDA) and Principal Component Analysis (PCA).     

基于SOPC的复合式生理信号检测系统设计

设计完成了一种多生物电信号采集能力并能完成生物电信号模式识别和辅助诊断的复合式生物电信号检测系统。系统通过具备双通道的低噪声高共模抑制比的前置采集放大电路,可实现心电信号和表面肌电信号两种体表生物电信号的检测。通过FPGA硬件化实现的小波分解模块和在NiosⅡ软核中实现的FFT和BP神经网络算法,可以完成对采集到的心电信号心率监测、QRS波群的检测和ST段形态识别反馈监护者的健康信息;并通过提取表面肌电信号活跃段数据和时频域参数为运动性肌肉疲劳评估提供参考。系统通过LCD屏、音频输出和SD卡存储能够完成对信号实时波形和监护参数显示、报警输出和长时间监护数据的存储。     

High performance data compression method with pattern matching for biomedical ECG and arterial pulse waveforms

Biomedical waveforms, such as electrocardiogram (ECG) and arterial pulse, always possess a lot of important clinical information in medicine and are usually recorded in a long period of time in the application of telemedicine. Due to the huge amount of data, to compress the biomedical waveform data is vital. By recognizing the strong similarity and correlation between successive beat patterns in biomedical waveform sequences, an efficient data compression scheme mainly based on pattern matching is introduced in this paper. The waveform codec consists mainly of four units: beat segmentation, beat normalization, two-stage pattern matching and template updating and residual beat coding. Three different residual beat coding methods, such as Huffman/run-length coding, Huffman/run-length coding in discrete cosine transform domain, and vector quantization, are employed. The simulation results show that our compression algorithms achieve a very significant improvement in the performances of compression ratio and error measurement for both ECG and pulse, as compared with some other compression methods.     

A switchable scheme for ECG beat classification based on independent component analysis

A switchable scheme is proposed to discriminate different types of electrocardiogram (ECG) beats based on independent component analysis (ICA). The RR-interval serves as an indicator for the scheme to select between the longer (1.0 s) and the shorter (0.556 s) data samples for the following processing. Six ECG beat types, including 13900 samples extracted from 25 records in the MIT-BIH database, are employed in this study. Three conventional statistical classifiers are employed to testify the discrimination power of this method. The result shows a promising accuracy of over 99%, with equally well recognition rates throughout all types of ECG beats. Only 27 ICA features are needed to attain this high accuracy, which is substantially smaller in quantity than that in the other methods. The results prove the capability of the proposed scheme in characterizing heart diseases based on ECG signals.     

基于SVM的ECG传感器信号身份识别方法

通过心电图（ECG）传感器采集的信号在身份识别中得到了越来越广泛的应用.但小波滤噪结果往往通过主观判断,没有量化指标,滤波效果不理想;同时,对于ECG特征的提取没有考虑心率变化的影响,鲁棒性不佳.针对这2个问题,提出了一种通过信噪比和相关系数衡量预处理结果的办法,并且在特征的提取上只采用QRS波形,避开了易受心率影响的间期特征.最后使用了多种分类识别方法进行测试,得到了小样本下支持向量机（SVM）最适用于ECG识别的结论.     

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.     

Recognition of underwater transient patterns

Underwater transients present an unusual but unique recognition problem in that pattern characteristics and categories are not well defined, and the patterns are highly nonstationary. This paper examines the characterization, segmentation and classification of the transient events. A comparison with speech processing and recognition is also made. Although it is difficult to fully characterize the transient data, it is shown that by extracting event portions of the transient waveform through segmentation, a low order autoregressive model can provide an effective feature set for cluster analysis and event classification. Both the segmentation procedure and the recognition experiments with real data are presented in detail.     

Decision-based neural networks with signal/image classificationapplications

Supervised learning networks based on a decision-based formulation are explored. More specifically, a decision-based neural network (DBNN) is proposed, which combines the perceptron-like learning rule and hierarchical nonlinear network structure. The decision-based mutual training can be applied to both static and temporal pattern recognition problems. For static pattern recognition, two hierarchical structures are proposed: hidden-node and subcluster structures. The relationships between DBNN's and other models (linear perceptron, piecewise-linear perceptron, LVQ, and PNN) are discussed. As to temporal DBNN's, model-based discriminant functions may be chosen to compensate possible temporal variations, such as waveform warping and alignments. Typical examples include DTW distance, prediction error, or likelihood functions. For classification applications, DBNN's are very effective in computation time and performance. This is confirmed by simulations conducted for several applications, including texture classification, OCR, and ECG analysis.     

Quasi-supervised learning for biomedical data analysis

We present a novel formulation for pattern recognition in biomedical data. We adopt a binary recognition scenario where a control dataset contains samples of one class only, while a mixed dataset contains an unlabeled collection of samples from both classes. The mixed dataset samples that belong to the second class are identified by estimating posterior probabilities of samples for being in the control or the mixed datasets. Experiments on synthetic data established a better detection performance against possible alternatives. The fitness of the method in biomedical data analysis was further demonstrated on real multi-color flow cytometry and multi-channel electroencephalography data.     

Evaluation of bagging ensemble method with time-domain feature extraction for diagnosing of arrhythmia beats

We explore the effect of using bagged decision tree (BDT) as an ensemble learning method with proposed time-domain feature extraction methods on electrocardiogram (ECG) arrhythmia beat classification comparing with single decision tree (DT) classifier. RR interval is the main property which defines irregular heart rhythm, and its ratio to the previous value and difference from mean value are used as morphological feature extraction methods. Form factor, its ratio to the previous value and difference from mean value are used to express ECG waveform complexity. In addition, skewness and second-order linear predictive coding coefficients are added to the feature vector of 56,569 ECG heart beats obtained from MIT–BIH arrhythmia database as time-domain feature extraction methods. The quarter of ECG heart beat samples are used as test data for DT and BDT. The performance measures of these classifiers are evaluated using the metrics such as accuracy, sensitivity, specificity and Kappa coefficient for both classifiers, and the performance of BDT classifier is examined for number of base learners up to 75. The BDT results in more predictive performance than DT according to the performance measures. BDT with 69 base learners has 99.51 % of accuracy, 97.50 % of sensitivity, 99.80 % of specificity and 0.989 of Kappa coefficient while DT gives 98.78, 96.05, 99.57 and 0.975 %, respectively. These metrics show that the suggested BDT increases the numbers of successfully identified arrhythmia beats. Moreover, BDT with at least three base learners has higher distinguishing capability than DT.     

可佩戴式远程心电采集终端的设计与实现

心电数据是诊断人体心脏状态的重要指标,在互联网大数据时代,远程医疗已成为一种趋势。为解决传统心电采集移动性和远程传输问题,而研制出一款可佩戴式远程心电采集终端。它由心电采集模块ADS1198、中央处理模块STM32、显示OLED液晶模块、USB模块、4G模块构成。能实时采集人体心电信号,并进行滤波处理,再通过OLED液晶模块大致显示心电波形。该设备具有通过USB模块传输数据至电脑实行近程心电数据管理或4G模块传输数据至医院监听端实现远程心电接收的功能。其体积为,重量仅为50g,工作电流仅为12.8mA。设备体积小巧,功耗低,便于佩戴,能采集医院分析病理的标准12导联心电数据,适用于在家庭中使用。     

An Interleaving Transformation for Parallelizing Reductions for Distributed-Memory Parallel Machines

Reduction operations frequently appear in algorithms. Due to their mathematical invariance properties (assuming that round-off errorscan be tolerated), it is reasonable to ignore ordering constraints on the computation of reductions in order to take advantage of the computing power of parallel machines.One obvious and widely-used compilation approach for reductions is syntactic pattern recognition. Either the source language includes explicit reduction operators, or certain specific loops are recognized as equivalent to known reductions. Once such patterns are recognized, hand optimized code for the reductions are incorporated in the target program. The advantage of this approach is simplicity. However, it imposes restrictions on the reduction loops—no data dependence other than that caused by the reduction operation itself is allowed in the reduction loops.In this paper, we present a parallelizing technique, interleaving transformation, for distributed-memory parallel machines. This optimization exploits parallelism embodied in reduction loops through combination of data dependence analysis and region analysis. Data dependence analysis identifies the loop structures and the conditions that can trigger this optimization. Region analysis divides the iteration domain into a sequential region and an order-insensitive region. Parallelism is achieved by distributing the iterations in the order-insensitive region among multiple processors. We use a triangular solver as an example to illustrate the optimization. Experimental results on various distributed-memory parallel machines, including the Connection Machines CM-5, the nCUBE, the IBM SP-2, and a network of Sun Workstations are reported.     

Adaptive Electrocardiogram Feature Extraction on Distributed Embedded Systems

Tiny embedded systems have not been an ideal outfit for high performance computing due to their constrained resources. Limitations in processing power, battery life, communication bandwidth, and memory constrain the applicability of existing complex medical analysis algorithms such as the Electrocardiogram (ECG) analysis. Among various limitations, battery lifetime has been a major key technological constraint. In this paper, we address the issue of partitioning such a complex algorithm while the energy consumption due to wireless transmission is minimized. ECG analysis algorithms normally consist of preprocessing, pattern recognition, and classification. Considering the orientation of the ECG leads, we devise a technique to perform preprocessing and pattern recognition locally in small embedded systems attached to the leads. The features detected in the pattern recognition phase are considered for the classification. Ideally, if the features detected for each heartbeat reside in a single processing node, the transmission will be unnecessary. Otherwise, to perform classification, the features must be gathered on a local node and, thus, the communication is inevitable. We perform such a feature grouping by modeling the problem as a hypergraph and applying partitioning schemes which yield a significant power saving in wireless communications. Furthermore, we utilize dynamic reconfiguration by software module migration. This technique, with respect to partitioning, enhances the overall power saving in such systems. Moreover, it adaptively alters the system configuration in various environments and on different patients. We evaluate the effectiveness of our proposed techniques on MIT/BIH benchmarks and, on average, achieve 70 percent energy saving.     

Multistage approach for clustering and classification of ECG data

Accurate and fast approaches for automatic ECG data classification are vital for clinical diagnosis of heart disease. To this end, we propose a novel multistage algorithm that combines various procedures for dimensionality reduction, consensus clustering of randomized samples and fast supervised classification algorithms for processing of the highly dimensional large ECG datasets. We carried out extensive experiments to study the effectiveness of the proposed multistage clustering and classification scheme using precision, recall and F-measure metrics. We evaluated the performance of numerous combinations of various methods for dimensionality reduction, consensus functions and classification algorithms incorporated in our multistage scheme. The results of the experiments demonstrate that the highest precision, recall and F-measure are achieved by the combination of the rank correlation coefficient for dimensionality reduction, HBGF consensus function and the SMO classifier with the polynomial kernel.     

小型化心电信号检测系统设计

为了克服心脏疫病突发就医不及的安全隐患,早期心脏疾病早发现、早治疗,开发了一种基于嵌入式微控制器的小型化心电信号检测系统,该系统包含心电信号采集硬件、控制系统软件以及心率转换算法设计,实现对被测者心电图、呼吸波及心率的获取,利用串口通信方式,上传给串口屏显示模块,并且设计了一套基于心电信号检测的Qt上位机软件系统,可实...     

Electrocardiogram (ECG) pattern modeling and recognition via deterministic learning

A method for electrocardiogram （ECG） pattern modeling and recognition via deterministic learning theory is presented in this paper. Instead of recognizing ECG signals beat-to-beat, each ECG signal which contains a number of heartbeats is recognized. The method is based entirely on the temporal features （i.e., the dynamics） of ECG patterns, which contains complete information of ECG patterns. A dynamical model is employed to demonstrate the method, which is capable of generating synthetic ECG signals. Based on the dynamical model, the method is shown in the following two phases： the identification （training） phase and the recognition （test） phase. In the identification phase, the dynamics of ECG patterns is accurately modeled and expressed as constant RBF neural weights through the deterministic learning. In the recognition phase, the modeling results are used for ECG pattern recognition. The main feature of the proposed method is that the dynamics of ECG patterns is accurately modeled and is used for ECG pattern recognition. Experimental studies using the Physikalisch-Technische Bundesanstalt （PTB） database are included to demonstrate the effectiveness of the approach.