MIT-BIH心率失常数据库的识读及应用

本文对美国MIT-BIH心率失常数据库的数据文件的格式进行了研究,提出的识读方法可使使用该数据库数据的研究人员能绕过其工具包而灵活地使用这些数据.本文还以其中一段数据记录为例进行了说明.     

HRV的最大李雅普诺夫指数估计

对心率变异性(HRV)进行了研究,比较了心率正常者与心率失常者HRV之间的最大李雅普诺夫指数上的差别。人在正常状态和病理状态下的HRV信号最大李雅普诺夫指数是不同的,当出现病理心血管事件时,指数α减少,因此李雅普诺夫指数可作为人体是否异常或处于何种异常状态的特征刻画指标,本文心率正常者HRV信号的最大李雅普诺夫指数为0.45907,心率不齐者的最大李雅普诺夫指数是0.41472。它们均为混沌信号,但是处于心率不齐状态的节律混沌程度明显比处于心率正常状态的节律混沌程度低。     

R-R Lorenz图实现心电信号混沌特征识别的研究

鉴于心电信号的非线性特征,采用混沌理论分析其混沌特征.从几类常见的窦性心率的心电信号中提取R-R间期,并绘制R-R Lorenz图,再对其图形特征进行处理及识别,得出结论性结果.研究结果可做为动态心电监护仪识别软件中的一项参考指标,提高心电监护仪的检测效率及精度,以期达到早期诊断心血管疾病的目的.     

普通高校田径教学课中的生理负荷强度分析

调查普通高校田径教学课中的生理负荷强度分布。采用抽样调查的方法,对80名普通高校一年级不同班级学生,在上田径课时的运动心率进行了监测调查。结果显示:(1)生理负荷变化的瞬时时间点,开始时刻心率为80次/min,第一拐点出现的时间是运动开始后的第28 min,此时的心率是132次/min,斜率是-0.031,表示心率变化的快慢和方向。(2)动员阶段和疲劳阶段都持续了28 min左右,负荷量分别是90.09 kUw和104.126 kUw(kUw,表示单位)。在动员阶段的平均反应强度是133次/分,而在疲劳阶段达140次/min。稳定阶段的负荷量是84.231 kUw。(3)各强度水平区间(PMI max)负荷量的分布情况。心率在区间120～140次/min和140～150次/min,负荷比值分别占总的32.786%和31.316%。心率在120～150次/min之间,负荷比值达到64.102%,而在150～160次/min之间,负荷比值仅占17.639%。普通高校田径课的生理负荷强度分布符合人体机能变化规律,但生理负荷强度处在较低的水平,不能充分起到增强和提高学生体能、体质的目的。教师应充分重视心率在训练过程中...     

多目标优化方法检测随机受迫系统的混沌现象以及在心率变异信号分析中的应用

心率变异信号往往很不规则 ,确定它是混沌还是噪声是目前研究的焦点。从非线性动力学的角度 ,虽然已进行了大量的工作 ,但迄今还没有明确的证据表明心率变异信号是混沌的。本文假设心率变异信号是其内在动力学机制和外部环境影响混合的产物 ,并提出一种多目标优化方法 ,以此获得一组既与心率变异信号尽可能接近又对于某种非线性动力学系统为确定的序列 ,然后计算依赖于初始值敏感的特征指数 ,定量刻划系统中确定性因素的动力学特性。在成功地检验了两类受迫混沌模型后 ,应用于心率变异信号分析 ,结果表明 :心脏动力学系统的确定性部分是混沌的     

基于非负盲分离的胎儿心率检测方法

胎儿心率监测是一种有效评估胎儿当前健康状况的重要参考依据。为了可以快速准确地获取胎儿心率,该文提出一种基于非负盲分离的胎儿心率检测方法。该方法首先对采集得到的腹壁信号进行预处理,平稳小波变换后重构出母亲心电信号;接着,采用相减法去除母亲心电信号,再把剩下含有噪声的胎儿心电信号通过时频变换得到Born-Jordan分布;最后,利用非负矩阵分解得到胎儿心电的特征信号,检测其R波位置求得胎儿瞬时心率。实验结果表明,该方法可以快速、准确有效地获得胎儿地瞬时心率数据。     

妊娠期糖尿病孕妇心率变异性变化

目的:探讨妊娠期糖尿病孕妇心率变异性变化.方法:选取阳春市妇幼保健院2018年1月至2020年4月收治的50例妊娠期糖尿病患者作为观察组,选取同期健康孕检孕妇50例作为对照组,年龄20～36岁,孕周24～40周.所有孕妇给予动态心电图监测,比较两组孕妇平均心率(AHR)、正常窦性RR间期的总体标准差(SDNN)、每5 ...     

正常家兔心率变异特点

目的:记录测定正常家兔在体和离体短程心率变异情况,探讨心脏自主神经功能的变化情况,为进一步研究家兔冠状动脉粥样硬化、冠脉痉挛时自主神经变化反映在心率变异性上的特点提供基础数据.方法:在体组用正交法记录胸前心电;离体组,采用兰氏(Langendorff)心脏灌流系统基础上,用正交悬浮电极法记录心电.采用Powerlab/8sp多道生理仪采集心电波.利用Chart模块对电信号进行短程心率变异分析.结果:正常家兔在体和离体组,短程心率变异分析结果值有明显不同.结论:正常家兔短程HRV特征较人体有明显区别,其频段取值范围有明显差异;在体与离体组HRV差异与神经体液调节因素有关.     

心率缺失数据插值方法探讨

在信号的记录和处理中,缺失数据导致信号不完整的情况常常存在。在记录心电信号时,由于种种原因,RR间期信号偶尔会出现连续的一段空白,即存在缺失数据。为了探究RR间期缺失数据的几种插值方法的优劣,本文提出并应用了一种用logistic混沌序列插值的新方法。采用年老组和年轻组各13名健康受试者的RR间期序列为实验数据,随机除去部分连续数据段,构造数据缺失序列。根据除去数据段的长短不同,构造不同缺失率的模拟数据。用线性插值、样条插值和Logistic混沌序列插值三种方法对缺失段进行模拟,分别计算原始数据和模拟数据的近似熵和样本熵两个指标,比较同一缺失率下三种插值方法的模拟效果。通过计算,得到结果:在相同的缺失率下,混沌序列可以较好的模拟缺失数据,插值200个点后的样本熵与原始值无明显变化(年老组p=0.3;年轻组p>0.2),而线性、样条模拟的样本熵与原始值相比有明显改变(p<<0.01)。最终我们有初步结论:在缺失率较小时,三种方法的模拟效果差异不大。随着缺失数据的增多,三种方法的模拟效果都有逐渐降低的趋势。三种方法的模拟效果与缺失率有关。在一定缺失率下,混沌序列插值方法优于线性插值和样条插值方法。     

贴敷式局部亚低温脑保护作用的研究

人类应用低温于医疗可以追溯到两千多年前,那时古埃及人就已经应用冷敷的方法止痛获得效果.20世纪50年代,人们曾在心血管手术中应用深低温(＜28℃)以保护脑和其他重要器官.自此以后,国外学都致力于将中、深低温用于脑保护和脑复苏的研究,发现确有显著的脑保护作用,然而深低温同时不可避免引起心率失常、凝血功能障碍等严重的并发症,限制了其临床应用.     

Inhibition of neuronal nitric oxide reduces heart rate variability in the anaesthetised dog

In the vagally intact anaesthetised dog, we have investigated the role of nitric oxide (NO) on a normal sinus arrhythmia using an inhibitor of neuronally released NO, 1-(2-trifluoromethylphenyl) imidazole (TRIM). The mean and S.D. of the R-R interval was used to describe mean heart rate and heart rate variability, respectively. TRIM (0.8 mg I.C.) injected into the sinus node artery increased the mean heart rate slightly but reduced heart rate variability 3-fold from a control of 790 +/- 124 ms (mean +/- S.D.; n = 5) to 666 +/- 36 ms (P < 0.01 Student's paired t test, n = 5). These results suggest that neuronally released NO may have a vagal facilitatory role in the maintenance of sinus arrhythmia in the normal heart.     

Better quantification of neonatal respiratory sinus arrhythmia—progress by modelling and model-related physiological examinations

A large interindividual variability of parameters quantifying respiratory sinus arrhythmia were found in a well defined group of healthy neonates during constant conditions of examination. Reasons for this can be found by means of a mathematical model which is based on physiological data. The results indicate sharp inconsistencies in the transfer function between respiratory movements and resulting respiratory sinus arrhythmia and are dependent on a relative frequency unit f_N (ratio of mean respiration rate to mean heart rate). The values of the coherence (as a function of this relative frequency unit) between respiratory movements and heart rate are also distinguished by a systematic decrease from lower to higher f_N values (f_N=0·1–0·5) and inconsistencies in modelling as well as in physiological examinations. The reasons for both effects can be demonstrated. The study is the basis of a new qualitative step of quantification of respiratory sinus arrhythmia in neonates by power spectral and coherence analyses.     

Relationship between heart rate and sinus arrhythmia in air traffic controllers at work

Summary Sinus arrhythmia and mean heart rate were calculated from continuous electrocardiogram recordings of ten air traffic controllers. The telemetric recordings were carried out during 1 day of work and the following day's night shift. The individual variations of sinus arrhythmiz were very large. The different situations (rest, relaxed work, intense work, eating, movements within the control room) had no specific effect on sinus arrhythmia. For each subject and for each group it was the value of the mean heart rate and its temporal variations that had the greatest influence on variations of sinus arrhythmia. This study was carried out thanks to a financial support of the D.G.R.S.T.     

Development and Stability in Visual Sustained Attention in 14, 20, and 26 Week Old Infants

Infants were studied at 14, 20, and 26 weeks of age in a longitudinal design. They were presented with varying and complex patterns on a TV screen. Two-thirds of the presentations were accompanied by a stimulus in the periphery delayed in time from the onset of fixation on the central stimulus. As in previous research, the infants were not as easily distracted by the interrupting stimulus when the presentation occurred at the point of maximal heart rate deceleration as when the presentation occurred at the end of the heart rate response. Infants with large amounts of respiratory sinus arrhythmia (i.e., heart rate variability) in a baseline recording were less distractible during the deceleration-defined trials than were infants with low amounts of respiratory sinus arrhythmia. Intra-individual patterns of development in respiratory sinus arrhythmia over the testing ages were closely paralleled by patterns of heart rate responding during sustained attention. Individual differences in baseline levels of heart rate and respiratory sinus arrhythmia were more stable than individual differences in sustained attention. The stability of attention responses over age may be mediated by the stability of the physiological system (e.g., heart rate, respiratory sinus arrhythmia, etc.), and by the within-age relation of attention to heart rate variability.     

Atropine abolishes electroencephalogram-associated heart rate changes without an effect on respiratory sinus arrhythmia during anaesthesia in humans

Heart rate fluctuates with the electroencephalogram burst suppression pattern during anaesthesia: increasing at burst onset and decreasing at suppression. Heart rate also oscillates with positive pressure ventilation. The effects of atropine on these heart rate changes were studied in 12 patients during isoflurane anaesthesia and positive pressure ventilation at a frequency of 6 cycles min^-1. Four additional patients served as controls. A bolus dose of atropine (20µg kg^-1 intravenously) abolished the electroencephalogram-correlated heart rate changes; however, the amplitude of respiratory sinus arrhythmia was not changed after atropine. The control mechanism of the burst suppression pattern in electroencephalogram also affects parasympathetic heart rate control. The control mechanisms of respiratory sinus arrhythmia during anaesthesia with positive pressure ventilation differ from those during spontaneous breathing awake.     

Prediction of Tonic Parasympathetic Cardiac Control Using Respiratory Sinus Arrhythmia: The Need for Respiratory Control

Respiratory sinus arrhythmia (RSA) has received much attention in recent years due to the large body of evidence indicating that variations in this phenomenon represent alterations in parasympathetic cardiac control. Although it appears that respiratory sinus arrhythmia is mediated by vagal mechanisms, the extent to which the well-known respiratory influences (i.e., rate and tidal volume) on respiratory sinus arrhythmia (in altering its magnitude) may moderate the relationship between RSA and cardiac vagal tone has never been systematically studied. We addressed this issue by examining intraindividual relationships among RSA magnitude, respiration (rate and tidal volume), and heart period among six healthy male adults after intravenous administration of 10 mg propranolol, a beta-adrenergic blocker. Subjects were exposed to various behavioral tasks which altered all physiological variables measured. Variations in heart period after beta blockade were assumed to be predominantly vagally mediated. Within-subject regression analyses consistently showed that respiratory parameters influenced RSA magnitude, but not tonic variations in beta-blocked heart period, suggesting that respiratory-mediated RSA alterations are not associated with changes in cardiac vagal tone. Only when respiratory variables were statistically controlled was there evidence of a reasonable correspondence between beta-blocked heart period and RSA amplitude, providing support for the idea that respiratory parameters need to be controlled when using RSA amplitude as an index of cardiac vagal tone. Repeated-measures analyses of variance of mean levels of heart period and respiratory sinus arrhythmia across subjects supplemented and supported the intraindividual results. These findings point to the importance of controlling for respiratory parameters when using respiratory sinus arrhythmia as a cardiac vagal index.     

Individual differences in the autonomic origins of heart rate reactivity: the psychometrics of respiratory sinus arrhythmia and preejection period

Heart rate reactivity has been conceptualized, at least implicitly, as a unidimensional construct ranging from low to high, reflecting individual differences in adrenergic reactivity to daily stressors. However, an individual's classification as high in heart rate reactivity ignores possible individual differences in the autonomic origins of this reactivity. Sixty-eight women were exposed to orthostatic and speech stressors to determine the psychometric properties (postural stability, convergent and discriminant validity) of heart rate, preejection period, and respiratory sinus arrhythmia. Results revealed that (a) basal, stress, simple reactivity (stress - baseline), and residualized change indices of heart rate, preejection period, and respiratory sinus arrhythmia were stable across postures and (b) heart rate reactivity was significantly related to preejection period and respiratory sinus arrhythmia reactivity, whereas the latter two measures were unrelated. Reactivity classifications may therefore be significantly improved by attention to concurrent estimates of the activity of both autonomic branches.     

Respiratory sinus arrhythmia is reversed during positive pressure ventilation

In order to study the relationship between heart rate and depth of anaesthesia, respiratory sinus arrhythmia (RSA) was investigated during enflurane and isoflurane anaesthesia in 28 patients (15-39 years). Positive pressure ventilation (six breaths min-1) was used. Respiratory sinus arrhythmia was evaluated during light anaesthesia, deep anaesthesia (burst suppression in EEG) and light anaesthesia again by using signal averaging technique. In most patients, decrease of the heart rate was seen during inspiration (positive tracheal pressure), and increase during expiration. Respiratory sinus arrhythmia did not disappear in deep anaesthesia. Inter-individual variation in the magnitude and phase relationship of respiratory sinus arrhythmia was considerable, and was not associated to the level of anaesthesia.     

Heart rate and heart rate variability in chicken embryos at the end of incubation

Our immediate goal was to study heart rate variability (HRV) in chicken embryos in the egg. Instantaneous heart rate data were needed for this purpose, and accordingly an ECG recording method in the egg was developed. The aim of this work was to test the hypothesis that autonomic nervous cardiac modulation, as shown from HRV parameters, is present at the end of development and that it reaches a constant value during the last days of incubation. Embryonic chicken heart rate was obtained at the final incubation period (days 19 and 20) from ECG recordings. Tachograms were computed and time- and frequency-domain indices of HRV were determined. No significant differences were found between HRV indices from day 19 and day 20. The power spectra extended in two frequency bands with centre frequency around 0.6-0.7 Hz (low frequency (LF) component), and another around 1.2-1.5 Hz (high frequency (HF) component); the latter was shown to reflect respiratory sinus arrhythmia. A relation between mean RR interval and some HRV parameters (rMSSD, pNN5 and HF power) was shown. HRV results obtained from embryonic chickens, showed the presence of modulation of cardiovascular function by the autonomic nervous system. The results suggested that sympathetic and parasympathetic activities have already reached a constant level at day 19 of incubation. High frequency oscillations (0.78-2.5 Hz) were detected and are considered to reflect respiratory sinus arrhythmia.     

Respiratory Sinus Arrhythmia and Cardiovascular Responses to Stress

The parasympathetic nervous system provides mechanisms that could attenuate sympathetically mediated heart rate stress responses and might have even more general antagonistic actions on stress reactivity. Individuals characterized by higher levels of parasympathetic tone might, through such mechanisms, be less reactive when stimuli elicit sympathetically mediated responses. Respiratory sinus arrhythmia (RSA) is considered to be a noninvasive index of cardiac parasympathetic (vagal) tone. The present study investigated whether individual differences in RSA level at rest could predict variations among individuals in the magnitude of cardiovascular responses to psychological stress. None of the measures of resting respiratory sinus arrhythmia, derived from spectral analysis of beat-to-beat changes in resting heart rate, predicted the observed variations in cardiovascular task reactivity. However, scores reflecting respiratory sinus arrhythmia as the percentage of total heart rate variability (RSAnorm) were negatively correlated with blood pressure levels, both at rest and during the task. Furthermore, subjects with higher scores for RSAnorm demonstrated a faster adaptation of heart rate responses during stress, which suggests the development of parasympathetic antagonism to ongoing sympathetic arousal. Although a simple relationship between respiratory sinus arrhythmia and reactivity was not observed, these results encourage further investigation of RSA measures as psychophysiological indices of individual differences in parasympathetic (vagal) cardiac tone, or perhaps of general parasympathetic/sympathetic balance, which could modulate the expression of potentially pathogenic stress responses.