心电记录仪频响范围不同时人和小鼠QRS波群峰峰值及波宽的比较研究

本文分析了当心电记录仪频响范围分别在０～５０Ｈｚ,０～１００Ｈｚ,０～２００Ｈｚ,０～５００Ｈｚ,０～１０００Ｈｚ５个频响范围时正常人和小鼠ＱＲＳ波群的峰峰值（Ｖｐ－ｐ）及波宽的变化。结果：正常人（ｎ＝２０）和正常小鼠（ｎ＝２０）,Ⅱ导联、ａＶＦ导联及Ｖ３导联的ＱＲＳ波群的Ｖｐ－ｐ,在０～１０００Ｈｚ频响范围内,均随着记录仪频响范围的增宽而增大。但正常人增幅极小,Ⅱ导联０～１０００Ｈｚ频响范围的ＱＲＳ波群的Ｖｐ－ｐ比０～１００Ｈｚ的仅增加了００３５ｍｖ,增幅仅为５９％;而小鼠的ＱＲＳ的Ｖｐ－ｐ增幅比人的大得多,Ⅱ导联０～１０００Ｈｚ频响范围的ＱＲＳ波群的Ｖｐ－ｐ比０～１００Ｈｚ的增加了０２５２ｍｖ,增幅为５２６％,是人的８９倍。小鼠及人的心电信号是在同一条件下记录的,通过对二者的比较,可认为小鼠的心电活动中,确实存在着高频信号,即小鼠高频心电图中的高频信号并非来自外界环境。人与小鼠Ⅱ、ａＶＦ、Ｖ３三个导联各频响范围的ＱＲＳ波宽均无明显差异。     

QRS波群功率谱与心率、QRS波宽、QRS峰-峰值相关性的研究

本文分别对２０个人和２１只小鼠各作为一个群体以及将２０个人和２１只小鼠合在一起作为一个群体,研究了ＱＲＳ波群功率谱与心率、ＱＲＳ波宽、ＱＲＳ峰－峰值的相关性（本文只分析了Ⅱ、ａＶＦ、Ｖ３导联）。发现人、鼠各作为一个群体时,ＱＲＳ波群的１００－１０００Ｈｚ、８０－３００Ｈｚ的相对能量及绝对能量,０－１０００Ｈｚ的总能量与心率、ＱＲＳ波宽、ＱＲＳ波群的峰－峰值之间的相关关系,在不同导联中,无明显的规律性。而当人、鼠合在一起作为一个群体时,ＱＲＳ波群功率谱中１００－１０００Ｈｚ、８０－３００Ｈｚ的相对能量和绝对能量都与心率呈显著正相关（Ｐ＜０．０１）,而０－１０００Ｈｚ总能量与心率呈显著负相关（Ｐ＜０．０１）;ＱＲＳ波群功率谱中１００－１０００Ｈｚ、８０－３００Ｈｚ的相对能量和绝对能量都与ＱＲＳ波宽呈显著负相关（Ｐ＜０．０１）,而０－１０００Ｈｚ总能量与ＱＲＳ波宽呈正相关（Ｐ＜０．０５）;１００－１０００Ｈｚ、８０－３００Ｈｚ的相对能量、绝对能量和０－１０００Ｈｚ总能量与ＱＲＳ波群的峰－峰值均呈正相关。     

正常人不同年龄组QRS波群频谱特征的研究

本文分析了１３１例健康者的Ⅱ、ａＶＦ、Ｖ２、Ｖ５导联中ＱＲＳ波群的频谱，并在各年龄组之间进行了各频段相对能量分布的比较。其结果：Ⅱ导中，４０－１００Ｈｚ频段内的相对能量，中老年组低于幼儿组，６０－８０Ｈｚ频段内表现的更加明显（Ｐ＜０．０５），ａＶＦ、Ｖ２、Ｖ５导联分别在３０－７０Ｈｚ、３１－５０Ｈｚ、３０－１００Ｈｚ频段内，随着年龄的增加，相对能量呈逐渐降低趋势；０－１０Ｈｚ的能量与１１－２０Ｈｚ的能量之比的均数，在各年龄组，各导联中几乎全部≥１（Ｖ５导联中学龄儿童组除外）；各年龄组各导联的相对能量，主要分布于０－８０Ｈｚ频段内，占总能量的９９．８％，８０－１０００Ｈｚ频段内的能量仅占０．２％，在１０１－１０００Ｈｚ频段内的能量占０．１％；年龄与最高频率之间呈负相关（Ｐ＜０．０１），心率与最高频率呈正相关（Ｐ＜０．０１）。     

心电信号及各组分的频率分布和有效带宽研究

本文用等长数据分析法对３４例１９－３０岁健康人的心电信号进行ＦＦＴ分析，以自身整个心动周期信号总功率的千分之一水平为标准（自适应的）确定了整个心动周期心电信号各频段功率（绝对和相对）的分布，报告了整个心动周期信号带宽为０－５８±１９Ｈｚ，Ｐ波带度为０－８±３Ｈｚ，ＱＲＳ波带宽为０－５５±１９Ｈｚ，Ｔ波带宽为０－１１±２Ｈｚ．研究表明心电信号的能量主要集中在低频段，随着频率增高相应的能量逐渐降低．心电信号存在高频成分，甚至是５００Ｈｚ以上的成分．     

急性心肌梗塞高频心电谱的动态变化

采用小波转换的三维频谱分析,对兔急性心肌梗塞模型的高频心电信号进行对比研究,结果提示急性心肌梗塞三维高频心电谱呈动态变化趋势,在缺血１０ｍｉｎ内出现频谱增宽,高频、甚高频能量增加;而后出现甚高频能量与高频能量分离现象。提示高频能量增加及其与甚高频能量的分离现象可能对急性心肌缺血的诊断有指导意义。     

老年及青年Wistar大鼠心电图QRS波时域及频域分析的比较研究

本文报道了老年及青年Ｗｉｓｔａｒ大鼠Ⅱ导联心电图ＱＲＳ波的时程、波幅及频谱特性，并分析了老龄对其时域值及频谱的影响，结果如下：（１）ｍ青年及老年鼠ＱＲＳ波时程及波幅；老年鼠与青年鼠相比，ＱＲＳ波时程延长（Ｐ〈０．０１）崦波幅减少（Ｐ〈０．０５）；（２）青年及老年鼠ＱＲＳ波频谱特征；青年鼠ＱＲＳ波频产呈双峰型，可分为两型：大部分鼠（１３／２１只）第一峰大，少部分鼠（８／２１只）第二峰大，老年鼠频谱图     

心肌炎患者高频心电图QRS波群的功率谱分析

本文选取６９名心肌炎患者，９４名正常人做为对照。依其年龄不同，共分６组：幼儿心肌炎组，正常幼儿组，学龄心肌炎组，正常学龄组，成人心肌炎组，正常成人组。分别对这６组的Ⅱ导、ａＶＦ导、Ｖ２导、Ｖ５导ＱＲＳ波群０－１０００Ｈｚ、８０－３００Ｈｚ、１００－１０００Ｈｚ３个频段的功率谱（用绝对能量表示）进行了分析。结果提示，不同年龄的心肌炎患者，其心电信号高频频段的能量变化规律不一致。     

一种抑制50Hz工频干扰的方法——基于FTF算法的自适应滤波

在长时间动态心电记录（ＨＯＬＴＥＲ）系统中５０Ｈｚ工频干扰会影响ＥＣＧ信号的质量和可诊断性，从而对ＱＲＳ复波的自动识别及节律分析产生不良影响。因此消除５０Ｈｚ工频干扰在ＥＣＧ信号予自理中占有重要地位。５０Ｈｚ工频干扰的频率和幅度是随着电网我参数的波动而变化的。从本质上讲，５０Ｈｚ工频干扰的波动过程是一种非平稳随机过程，采用固定的窄带隐波器对５０Ｈｚ工频干扰进行去除，不可能完全抑制５０Ｈｚ工频干扰，     

CoxsackieB＿3病毒对小鼠Ⅱ导联QRS波群功率谱的影响

将健康Ｂａｌｂ／ｃ小鼠腹腔注射Ｃｏｘｓａｃｋｉｅ病毒（ＣＢ＿３Ｖ），对其种毒前及种毒后第１，３，５，７天的高频心电图（ＨＦ－ＥＣＧ）Ⅱ导联ＱＲＳ波群的功率谱进行分析。结果表明，种毒后低频（０－８０Ｈｚ）相对能量较种毒前降低，而高频（７８０Ｈｚ）各频段相对能量均较种毒前升高，即病毒使心电活动的高频相对能量升高，对照组无此变化。结果提示：功率谱可能成为检测病毒性心肌炎的一项新的辅助指标。     

心电特征点定位算法

作者对心电特征点的定位进行实验研究，采有 域变换算法对ＱＲＳ波及Ｔ波特征点进行准确提取，提出根据正负峰点位置对ＱＲＳ波群模式分类和利用峰值差别Ｔ波极性的方法。局域变换算法使心电特征点的特性更为突出，唯一性较好；ＱＲＳ波群形成的峰值位置判别和Ｔ波极性的峰值判别方法计算简单，为局域变换算法的实现打下了基础。     

家兔心房电活动的频谱分析

本文报道家兔正常心电图P波的频谱特征及损伤心房后P波频谱的变化。结果表明,正常家兔心电图P波频谱能量主要集中在1—4 Hz的低频峰段。损伤心房肌后,表现为P波变宽,频谱能量分布发生变化,1Hz的功率明显增加,而2Hz的功率明显减弱。提示 心房损伤后,P波频谱能量分布向更低频率段转移。     

正常人QRS波群高频频段功率谱稳定性初探

本文分析了１３例正常青年大学生的高频心电图ＱＲＳ波群高频频段功率谱（＞８０Ｈｚ）在不同个体之间以及同一个体不同时间的变异程度，并与临床上常用的生理指标和心电图时域值指标（包括体温、动脉血压、心率、Ｐ、Ｒ间期ＱＲＳ波宽、Ｑ－Ｔ间期）的变异程度作了比较结果表明，高频频段功率谱的测量值在人群中因人体和时间的不同变化很大，其变异系致是常用生理指标变异系数的１０－１００倍。由此，对高频心电图高频频段功率谱的稳定性提出了疑认为能否作为一项判断指标厘用于临床尚需进一步研究。     

Pseudo-real-time low-pass filter in ECG,self-adjustable to the frequency spectra of the waves

The electrocardiogram (ECG) acquisition is often accompanied by high-frequency electromyographic (EMG) noise. The noise is difficult to be filtered, due to considerable overlapping of its frequency spectrum to the frequency spectrum of the ECG. Today, filters must conform to the new guidelines (2007) for low-pass filtering in ECG with cutoffs of 150 Hz for adolescents and adults, and to 250 Hz for children. We are suggesting a pseudo-real-time low-pass filter, self-adjustable to the frequency spectra of the ECG waves. The filter is based on the approximation procedure of Savitzky–Golay with dynamic change in the cutoff frequency. The filter is implemented pseudo-real-time (real-time with a certain delay). An additional option is the automatic on/off triggering, depending on the presence/absence of EMG noise. The analysis of the proposed filter shows that the low-frequency components of the ECG (low-power P- and T-waves, PQ-, ST- and TP-segments) are filtered with a cutoff of 14 Hz, the high-power P- and T-waves are filtered with a cutoff frequency in the range of 20–30 Hz, and the high-frequency QRS complexes are filtered with cutoff frequency of higher than 100 Hz. The suggested dynamic filter satisfies the conflicting requirements for a strong suppression of EMG noise and at the same time a maximal preservation of the ECG high-frequency components.     

QRS subtraction for atrial electrograms: flat,linear and spline interpolations

The main objective of this article is to implement and compare QRS subtraction techniques for intra-cardiac atrial electrograms based on using the surface ECG as a reference. A band-pass filter between 8 and 20 Hz followed by rectification, and then a low-pass filter at 6 Hz are used for QRS detection. QRS subtraction was performed using three different approaches: flat, linear and spline interpolations. QRS subtraction affects the power of the signals but it normally does not affect the dominant frequency. The average power of the atrial electrograms after QRS subtraction is significantly reduced for frequencies above 10 Hz.     

家兔心肌缺血再灌注前后心电高频成分的变化

急性心肌梗塞溶栓治疗过程中冠状动脉是否再通的判断比较困难。结扎家兔冠状动脉左室支３０分钟再灌注２１０分钟，用高频心电图三维谱分析法观察中高频成分、甚高频成分的变化。结果表明：心肌缺血时，中高频成分、甚高频成分减少，再灌注后逐渐恢复。     

Fast and reliable QRS alignment technique for high-frequency analysis of signal-averaged ECG

The process of QRS alignment as required in signal-averaged ECG can impose serious limitations on the spectral range of the signal output. This effect depends basically on the particular alignment technique being used and on the level and type of noise present in the recorded ECG. In clinical studies where a wide-band (1000 Hz) ECG averager is required, the conventional QRS alignment technique, based on maximum coherence matching (MCM) with a template beat, may not perform consistently well. An alternative QRS alignment technique based on the accurate detection of a single fiducial point (SFP) in the bandpass filtered (3–30 Hz) QRS complex was developed. Using computer simulation methods, a comparative assessment of the frequency bandwidths (3 dB points) offered by both MCM and SFP techniques as a function of noise level (15–100 μ RMS) and type (EMG and 50 Hz interference), was carried out. The results of the comparative assessment indicated a better performance by the SFP technique in all cases of noise. Hence, the SFP technique would perform more reliably for high-frequency analysis of a noisy ECG, especially when 50 Hz interference is high. Furthermore, SFP is considerably faster than MCM (about four times) when implemented digitially, and its analogue realisation is feasible. The SFP technique is suitable for late-potential analysis in the signal-averaged ECG.     

Hand dominance during constant force isometric contractions: evidence of different cortical drive commands

The purpose of this study was to investigate force variability and sensoriomotor strategies of dominant and nondominant hands of right and left-handed subjects during a submaximal isometric force production task. Twelve right-handed adults (9 men and 3 women; 23?±?3?year) and twelve left-handed adults (4 men and 8 women; 24?±?3?year) performed an isometric constant force contraction sustained at 30 and 50% of maximal force for 10?s. Surface EMG signals were obtained from forearm flexors and extensors. Force signals were analyzed in the time (CV of force) and frequency (0-10?Hz) domain. The neural activation of the involved muscles was investigated from the EMG structure using the cross-wavelet spectra of the interference EMG signals of six different frequency bands of the EMG signals were quantified (5-13, 13-30, 30-60, 60-100, 100-150 and 150-200?Hz). The major findings were: (1) dominant and nondominant hands of right- and left-handed subjects exhibited similar CV of force; (2) the power spectrum of force is influenced by handedness, with greater 1-3?Hz oscillations for left-handed subjects when compared to right-handed subjects; (3) right-handed subjects have greater 30-60?Hz neuromuscular activation when compared to left-handed subjects. Our results indicate that right-handed individuals may rely preferentially in visual feedback to carry out a task with visual and proprioceptive feedback because of the left hemisphere specialization on the visuomotor control.     

Effect of frequency and pulse duration on human muscle fatigue during repetitive electrical stimulation

Different combinations of stimulation frequency and intensity can generate a targeted force during functional electrical stimulation (FES). This study compared isometric performance and muscle fatigue during repetitive stimulation with three different combinations of frequency and pulse duration that produced the same initial peak forces: protocol 1 used long pulse duration (fixed at 600 micros) and 11.5 +/- 1.2 Hz (low frequency); protocol 2 used 30 Hz (medium frequency) and medium pulse duration (150 +/- 21 micros); and protocol 3 used 60 Hz (high frequency) and short pulse duration (131 +/- 24 micros). Twenty and 60 Hz pre- and postfatigue testing trains were delivered at the pulse duration used by the fatiguing trains and at 600 micros pulse duration. The percentage decline in peak force between the first and last fatiguing train of each protocol was the measure of muscle performance. The declines in peak force of the 60 Hz testing trains were used to measure muscle fatigue. The 20 Hz:60 Hz peak force ratio was used as a measure of low-frequency fatigue. The results showed that protocol 1 produced the least decline in peak force in response to the fatiguing trains, as well as the least muscle fatigue and low-frequency fatigue when the pulse duration was maintained at the level used by the fatiguing trains. Interestingly, protocol 2 produced the least muscle fatigue, and there were no differences in the levels of low-frequency fatigue across protocols when a comparable motor unit population was tested using 600 micros pulse duration. The results suggest that if the frequency and intensity are kept constant during FES, using the lowest frequency and longest pulse duration may maximize performance.     

神经网络分析方法用于心脏病诊断的研究

神经网络可以很好的拟合任意的非线性函数。我们从 QRS波群的高频三维频谱中提取出一些定量的特征参数 ,用神经网络的方法对这些参数进行有监督的学习训练 ,最终能在由这些特征参数张成的 m维空间中构建出一个 m维的曲面来区分病人和健康人的 QRS波群高频三维频谱 ,从而使得训练后的网络能基于 QRS波群的高频三维频谱自行诊断出病人和健康人