Continuous and online analysis of heart rate variability

Spectral analysis of heart rate variability provides a probe to assess the function of the sympathetic and parasympathetic nervous systems. Time-frequency analysis of heart rate variability is useful for investigating autonomic nervous function in patients with syncope or non-sustained ventricular tachycardia, or in anaesthesia, etc. In this paper, we developed an algorithm for continuous and online analysis of heart rate variability. The algorithm was simulated and evaluated in MATLAB, and implemented on the digital signal processor. The electrocardiogram signals from MIT/BIH arrhythmia database and one patient with syncope demonstrate the capability of the proposed method in the continuous and online analysis of heart rate variability.     

Time-Frequency Analysis of Heart Rate Variability During Transient Segments

The spectral characteristics of heart rate variability (HRV) are related to the modulation of the autonomic nervous system. As the physiological condition is changed by such external stimuli such as drugs, postural changes, and anesthesia, or by internal deregulation such as in syncope, adjective autonomic responses could alter HRV characteristics. Time-frequency analysis is commonly used to investigate the time-related HRV characteristics. An alteration of the autonomic regulation resulting in a change in mean heart rate induces a transient component in heart rate, which, with any analysis method based on signals from multiple beats, results in the apparent spread of the spectrum of frequencies. This obscures the spectral components related to the autonomic function. In this paper we investigated the influence of the transient component in several time-frequency methods including the short-time Fourier transform, the Choi-Williams distribution, the smoothed pseudo Wigner–Ville distribution (SPWVD), the filtering SPWVD compensation, and the discrete wavelet transform. One simulated signal and two heart rate signals during general anesthesia and postural change were used for this assessment. The result demonstrates that the filtering SPWVD compensation and the discrete wavelet transform have small spectrum interference from the transient component. © 2001 Biomedical Engineering Society. PAC01: 8719Hh, 8780-y     

Music,perceived arousal,and intensity: Psychophysiological reactions to Chopin's “Tristesse”

The present study investigates the relation of perceived arousal (continuous self‐rating), autonomic nervous system activity (heart rate, heart rate variability) and musical characteristics (sound intensity, musical rhythm) upon listening to a complex musical piece. Twenty amateur musicians listened to two performances of Chopin's “Tristesse” with different rhythmic shapes. Besides conventional statistical methods for analyzing psychophysiological reactions (heart rate, respiration rate) and musical variables, semblance analysis was used. Perceived arousal correlated strongly with sound intensity; heart rate showed only a partial response to changes in sound intensity. Larger changes in heart rate were caused by the version with more rhythmic tension. The low‐/high‐frequency ratio of heart rate variability increased—whereas the high frequency component decreased—during music listening. We conclude that autonomic nervous system activity can be modulated not only by sound intensity but also by the interpreter's use of rhythmic tension. Semblance analysis enables us to track the subtle correlations between musical and physiological variables.     

Can central neuropeptides be implicated in carotid sinus reflex hypersensitivity?

Carotid sinus reflex hypersensitivity involves profound and intermittent changes in heart rate and blood pressure associated with symptoms of dizziness and syncope. This involves a reflex arc in which the main defect is believed to lie within the central nervous system. The discovery of classical and peptidergic neurotransmitters within the same neurone, and the presence of these peptides within the central nervous system raises the possibility that carotid sinus reflex hypersensitivity may be related to an abnormality of peptide distribution or function.     

Power spectral analysis of heart rate and blood pressure variability in anaesthetized dogs.

Short-term oscillation of heart rate and blood pressure are mainly regulated by the automatic nervous system. It has been proposed that non-neural factors, such as changes in intrathoracic pressure, can strongly modulate this rhythmicity. Our aim was to evaluate the effect of changing intrathoracic pressure and central autonomic nervous activity on heart rate and blood pressure variability. Evaluation was performed by using spectral analysis techniques with autoregressive modelling. The variability in heart rate and blood pressure remained in animals with open chest or paralysed respiratory muscles. After vagotomy, the variability in heart rate decreased, but not that of blood pressure. Total spinal anaesthesia elicited a decrease in the variability in blood pressure. The pharmacological blockade of alpha- and beta-receptors further decreased both variabilities. It was concluded that in anaesthetized dogs heart rate and blood pressure variability are mainly of central origin and non-neural factors have only minor effect on these central rhythms. High (> 0.15 Hz), medium (0.07-0.15 Hz) and, obviously low (0.00-0.07 Hz) frequency variations in heart rate are mostly mediated vagally. In blood pressure, medium and obviously low frequency variations are modulated by sympathetic nervous system, whereas high frequency variations are secondary to the heart rate variation.     

Analysis of cardiac health using fractal dimension and wavelet transformation

Analysis of heart rate variation (HRV) has become a popular non-invasive tool for assessing the activities of the autonomic nervous system (ANS). HRV analysis is based on the concept that fast fluctuations may specifically reflect changes of sympathetic and vagal activity. It shows that the structure generating the signal is not simply linear, but also involves nonlinear contributions. These signals are essentially non-stationary; may contain indicators of current disease, or even warnings about impending diseases. The indicators may be present at all times or may occur at random in the time scale. However, to study and pinpoint abnormalities in voluminous data collected over several hours is strenuous and time consuming. This paper presents the continuous time wavelet analysis of heart rate variability signal for disease identification. Fractal dimension (FD) of heart rate signals are calculated and compared with the wavelet analysis patterns. The FD obtained indicates more than 90% confidence interval for all the classes studied.     

心率变异光谱分析定量测定偏头痛患者自主神经功能

心率变异光谱分析(SAHRV)定量测定65例偏头痛患者和50例健康人仰卧位和站立位自主神经系统(ANS)功能。结果发现,偏头痛患者站立位中频段积分较对照组显著降低(P<0.001),表明其交感功能低下,且随着疼痛程度的增加及病程的延长,其交感功能低下的程度亦越重。本文还初步探讨了其机理及临床应用意义。     

The effect of beta adrenergic stimulation on QT and QTc interval in syncope children with or without coexisting ventricular arrhythmias

We investigated the effect of beta-adrenergic stimulation on the heart rate and QT interval in syncope children with or without coexisting ventricular arrhythmias (VA). Of the 24 children who presented with syncope or presyncope and showed negative tilt test, 13 were classified into a group with VA and the remaining 11 without VA. The provocative test was performed in bolus infusion and continuous infusion. RR, QT, and QTc intervals on routine 12-lead surface electrocardiogram were obtained during each stage of isoproterenol infusion. In all cases, malignant ventricular arrhythmia and syncope were not induced by isoproterenol provocative test. RR and QT intervals were shortened and QTc intervals were prolonged as the isoproterenol dose was increased in both groups and methods. The QTc interval reached its peak level after the bolus injection of 1.0 microgram and during the continuous infusion of 0.03 microgram/kg/min. The two groups showed no significant difference in the QTc interval change according to the infusion methods. This study indicates that changes in the heart rate and QT interval by beta-adrenergic stimulation were not different according to the coexisting ventricular arrhythmias in syncope children with negative head-up tilt test.     

Heart rate variability in mice: a theoretical and practical guide

The mouse is the animal model principally used to study biological processes in mammals. The mutation, overexpression or knockout of one or several genes can provide insight into human disease. In cardiovascular research, evaluation of autonomic nervous function is an essential tool for a better understanding of the pathophysiological conditions in which cardiomyopathy arises and develops. Analysis of heart rate variability is the least invasive method to evaluate the sympathovagal balance on the sino-atrial level. The need to perform this technique on freely moving mice emerged in the 1990s, but despite previous studies it has been difficult to set up and standardize a common protocol. The multitudes of techniques used, plus subtle differences in methodology, impede the comparison and clear interpretation of results. This article aims to make a survey of heart rate variability analysis and to establish a standardized protocol for the assessment of the autonomic neural regulation of heart rate in mice.     

基于心率变异性谱分析的经穴磁刺激效应分析

目的：应用心率变异性（HRV）功率谱分析，探讨疲劳状态下，经穴磁刺激对自主神经功能的调整作用。方法：健康志愿人员20名，执行警惕操作任务90分钟后，施加经穴磁刺激15分钟。同时，时实记录实验者心电信号。结果：实验人员疲劳状态下，施加经穴磁刺激后，心率变异性发生显著性变化，表现为交感神经张力降低，迷走神经张力提高，主观评估疲劳程度降低。结论：经穴磁刺激有利于改善心率变异性，可一定程度上缓解精神疲劳。     

Effects of alcohol and smoking during pregnancy on infant autonomic control

Prenatal exposure to smoking and alcohol increases the risk for Sudden Infant Death Syndrome (SIDS). Physiological changes associated with these exposures are not well studied. Full‐term infants were tested within the first 3 days of life. We hypothesized that maternal alcohol consumption and/or smoking during pregnancy would alter autonomic nervous system function. Newborns whose mothers smoked during pregnancy had lower beat‐to‐beat heart rate variability in quiet sleep. Infants whose mothers consumed alcohol had lower global heart rate variability, but only in active sleep. Unexposed infants demonstrated increases in heart rate with head‐up tilt and decreases in heart rate with head‐down tilt, but smoking and alcohol‐exposed infants showed no significant responses. These results indicate that autonomic function is altered by prenatal exposure to alcohol and smoking. Such markers may provide early identification of infants at greatest risk for SIDS. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 234–242, 2009     

训练学参数与自主神经系统的适应

文题释义： 自主神经系统：是脊椎动物的末梢神经系统,由躯体神经分化、发展,形成功能上独立的神经系统,在调整心血管系统以适应肌肉活动的代谢需求过程中有重要调节作用,并且是身体活动最重要的表现者和支撑者。 心率变异性：是反映自主神经系统中交感神经和副交感神经(迷走神经)共同调控心功能的敏感标志物,其中包含着心血管系统、激素和体液等调节信息,可用来评价个体运动训练适应性效果。 背景：自主神经系统在调整心血管系统以适应肌肉活动的代谢需求过程中有重要调节作用,并且是身体活动最重要的表现者和支撑者。 目的：通过对国内外关于运动与自主神经系统、心率变异性评定自主神经系统的相关文献进行综述,系统梳理在运动中及运动后,运动强度、运动形式、运动时长对自主神经系统调控的可能影响,进而了解满足适应机体活动代谢需求的相关机制。 方法：检索PubMed等数据库,英文检索词为：“Autonomic nerves system” “Heart rate variability” “Exercise intensity”“Exercise modality”“Exercise duration”;并在中国知网数据库进行检索,中文检索词为：“自主神经系统”“心率变异性”“交感神经”。对文献进行筛选,时限为1999年至2018年,语言限制为中文和英文。 结果与结论：当前,心脏自主神经调节通常采用基于RR间期变化的心率变异性指标进行评定,心率变异性是反映自主神经系统中交感神经和副交感神经(迷走神经)共同调控心功能的敏感标志物,包含着心血管系统、激素和体液等调节信息。但目前对运动训练诱导心脏自主神经系统适应的机制尚不明确。运动强度可能是影响运动中和运动后心脏自主神经系统调节的主要影响因素,而运动形式、运动持续时间等训练学参数,以及它们的交互效应也可能影响心脏自主神经系统的调节适应过程。 ORCID: 0000-0001-8476-2771(陈艳林) 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Heart rate variability in diabetic patients during orthostatic load — A spectral analytic approach

Summary Spectral analysis of heart rate variability (HRV) was used to assess the autonomic nervous control of cardiac function during orthostatic load in insulin-dependent diabetic patients and healthy subjects. The diabetic patients were divided into three groups: diabetics without neuropathy (group 1), diabetics with peripheral neuropathy (group 2), and diabetics with peripheral and autonomic neuropathy (group 3). Resting mid-frequency (MF, 0.05–0.15 Hz) and respiration-related (RF, power around respiration rate) HRV were significantly lower in group 2 and 3 diabetics than in controls, indicating a reduced parasympathetic nervous system influence on the heart. Standing MF and RF spectral power data were significantly lower in all diabetic groups than in controls, suggesting marked alterations in the autonomic cardiovascular control during a mild physical load not only in symptomatic diabetics but also in patients with no signs and symptoms of neuropathy. The difference between supine and standing MF power, an estimate of-adrenergic influence on the heart, was significantly lower in all diabetic subject groups studied than in controls. This suggests a reduced sympathetic nervous system influence on the heart in diabetic patients. Our data suggest that computerized spectral analysis of HRV during orthostatic load seems to be a very sensitive method of evaluating of the autonomie nervous systems influence on the heart in patients suffering from diabetes niellitus.Abbreviations dB decibel - HRV heart rate variability - LF low-frequency component - MF mid-frequency component - RF respiration related frequency component     

基于多分辨率分析的心率变异性分析

目的：心率变异性蕴藏了大量有关心血管调节的信息,可作为定量反映自主神经功能及其对心血管的调控作用和反映心脏活动正常与否的重要指标之一。因此,主要研究了几种常用的心率变异性分析方法。方法：本论文应用多分辨率分析方法对HRV信号进行6尺度分解,计算小波系数的能量及其在各频段的分布,对cd3-cd6频段的能量进行分析比较。结果：充血性心衰患者各频段能量均值比正常人都要低,能量分别主要集中在高频段和低频段的偏低频部分,且两组的能量差异更为明显,与频域分析结果相比更为精确。结论：要得到带有普遍规律的实验结果,需要对不同的分析方法进行不断地改进和优化,并进行大量的研究工作。     

Decreased entropy of symbolic heart rate dynamics during daily activity as a predictor of positive head-up tilt test in patients with alleged neurocardiogenic syncope

Entropy measures of RR interval variability during daily activity over a 24h period were compared in 30 patients with a positive head-up tilt (HUT) test and 30 patients with a negative HUT test who had a history of alleged neurocardiogenic syncope. Two different entropies, approximate entropy (ApEn) and entropy of symbolic dynamics (SymEn), were employed. In patients showing a positive HUT test, the entropies were significantly decreased when compared with the patients with a negative HUT test. In addition, SymEn in the patients with a negative HUT test was significantly lower than in the normal controls. Discriminant analysis using SymEn could correctly identify 89.3% (520/582) of the 1 h RR interval data of the patients with a positive HUT test regardless of the time of day. Baseline entropies of heart rate dynamics during daily activity were found to be significantly lower in patients with alleged neurocardiogenic syncope and a positive HUT test than in those with the same history but with a negative HUT test. The decreased entropy of symbolic heart rate dynamics may be of predictive value of a positive HUT test in patients with alleged neurocardiogenic syncope.     

Time-frequency and time-varying analysis for assessing the dynamic responses of cardiovascular control

Time-frequency or time-variant methods have been extensively applied in the study of the heart-rate variability (HRV) signal. In fact, the frequency content of HRV signal has a strong correlation with the control system assessing heart rate. In particular, the power related to the low-frequency (LF) and high-frequency (HF) components have been demonstrated to correlate to the action of sympathetic and parasympathetic branches of the autonomic nervous system. However, the analysis is restricted to stationary conditions, unless time-frequency methods are employed for detecting dynamic changes that may occur during physiological and pathological conditions.This article reviews the most diffused tools for time-frequency analysis, starting from linear decomposition of the signal (including short-time Fourier transform and wavelet and wavelet packet decomposition), to quadratic time-frequency distributions (including Wigner-Ville transform and Cohen's class of distributions), and finally to adaptive or time-variant autoregressive (AR) models, in both the mono- and bivariate forms. In the past few years, these approaches have been applied in several studies related to cardiovascular responses during nonstationary pathophysiological events. Among them, we will recall and discuss myocardial ischemia (spontaneous or induced), drug infusion, rest-tilt maneuver and syncope, neurophysiological, and sleep investigations.     

Changes in autonomic cardiovascular control in mid-pregnancy.

Spectral analysis of heart rate variability was used to study autonomic nervous control in mid-pregnancy. Fifty women (age 22-36 years) with singleton pregnancies (mean duration of gestation 27.7 weeks) and 39 non-pregnant female controls (age 21-39 years) were studied using controlled breathing and orthostatic tests. During spontaneous breathing the overall heart rate variability was lower in pregnant subjects indicating a decreased parasympathetic tone at rest. The decreased parasympathetic tone probably counts for the increased heart rate in pregnancy. The parasympathetic efferent capacity of autonomic cardiac control was found to be similar in pregnant and non-pregnant subjects, as no difference was seen during controlled breathing in periodic heart rate variability between the groups. Standing up caused a similar change in low frequency and mid-frequency bands in both groups, but high frequency heart rate variability increased in pregnant subjects and decreased in the controls indicating an increased sympathetic tone at rest in mid-pregnancy.     

A novel online method to monitor autonomic nervous activity based on arterial wall impedance and heart rate variability

This paper proposes a new method of evaluating autonomic nervous activity using the mechanical impedance of arterial walls and heart rate variability. The cardiovascular system is indispensable to life maintenance functions, and homeostasis is maintained by the autonomic nervous system. Accordingly, it is very important to be able to make diagnosis based on autonomic nervous activity within the body’s circulation. The proposed method was evaluated in surgical operations; the mechanical impedance of the arterial wall was estimated from arterial blood pressure and a photoplethysmogram, and heart rate variability was estimated using electrocardiogram R–R interval spectral analysis. In this paper, we monitored autonomic nervous system activity using the proposed system during endoscopic transthoracic sympathetic block surgery in eight patients with hyperhidrosis. The experimental results indicated that the proposed system can be used to estimate autonomic nervous activity in response to events during operations.     

中重度抑郁症患者心电图及心率变异性分析

目的:探讨中重度抑郁症患者心电图及心率变异性特点,为临床评估中重度抑郁症心脏自主神经功能变化提供依据.方法:选择2018年6月至2019年12月就诊于湖南省脑科医院的中重度抑郁症患者38例为研究组,32例健康志愿者为对照组,比较两组心电图异常率及心率变异性,并统计分析各指标之间的差异.结果:研究组心电图异常ST-T改变...     

低氧与心率变异性研究进展

高原或运动等生理性低氧或/和临床心血管、呼吸及代谢等疾病病理性缺氧均可改变机体自主神经调节功能,从而导致心率变异性(HRV)变化。HRV对机体功能状态评定、多种疾病的诊断、预后及疗效评价具有重要价值。本综述简要介绍近年来有关低氧与HRV的研究进展。