心率变异性时频分析参数用于心电图ST段偏移时段的判别

利用ST段偏移时心率变异性（HRV）存在的变化,探讨区分ST偏移时段和正常时段,进而区分缺血或单纯心率改变引起ST段偏移的可行性。从Long-term ST-T（LTST）数据库免费下载的心电信号数据中,选取25个记录中缺血引起ST段偏移时段（105段）和单纯心率变化引起ST段偏移时段（43段）,以及所选时段前后各5min作为对照时段。选用平滑伪Wigner-Ville分布（SPWVD）,计算不同时域段和频域段的心率变异性（HRV）分析参数。利用Fisher线性判别和支持向量机进行判别分析,并采用留一法检验分类判别的正确率。对于Fisher线性判别,ST段偏移时段判别的正确率随时段持续时间的延长而减小,而不同诱因区分的正确率却较高（不低于89.7%）。支持向量机法对上述各种检测和分类判别的正确率均为100%。研究结果为从非形态学的角度检测ST段偏移时段的存在和产生原因的判别,提高心肌缺血判别的准确性,提供了有参考价值的信息。     

用HRV观察麝香保心丸对家兔急性心肌缺血的影响

实验在３２只戊巴比妥纳麻醉的新西兰兔上进行,记录心率、呼吸心电图和ＨＲＶ（心率变异性）频谱分析,以ＨＲＶ频谱成分指标分别记录正常时,正常加药对照组,急性心肌缺血时,缺血后加麝香保心丸时总变异性（ＴＶ）,低频成分（ＬＦ）,高频成分（ＨＦ）,低频成分和高频成分比值（ＬＦ／ＨＦ）,结果显示正常时与加药对照时的ＨＲＶＰ值均＞０．０５,其它除急性缺血时ＬＦ／ＨＦＰ值＞０．０５外,所有Ｐ值均＜０．００１,因而本实验提示,麝香保心丸能调整急性心肌缺血时自主神经功能,尤其是调整交感神经和迷走神经兴奋的适当比例,有益于心功能恢复,改善心肌缺血状态。     

正常人深呼吸对心率变异性的影响

心率变异作为一种间接评价心脏自主神经功能的分析方法,受到多种因素的影响,呼吸便是其中一个重要因素。文章通过心电图RR间期(RRI)序列,就呼吸对心率变异性的影响进行了时域、频域和非线性动力学分析。统计发现,深呼吸时RR平均间期变小,间期标准差(SDNN)变大,功率谱中低频成分(LF)增加,平衡比(LF／HF)变大,复杂度减小。结果表明,深呼吸可以使交感神经兴奋性增加,加快心跳频率,影响自主神经平衡,而RRI序列复杂度的减小可能与此时呼吸成为自主神经系统的主要调制因素有关。     

心率变异性在更年期综合征患者中的意义

目的 分析更年期患者的心率变异特点，研究更年期综合征（climacteric syndrome,CS)患者与自主神经功能之间的关系。方法 对65例更年期患者及100例健康女生做24h长程心率变异（HRV）比较，分析CS患者HRV的变化。结果 CS患者与健康女性相比较，其迷走神经活性明显增强，交感神经活性相对降低。结论 CS患者与迷走神经活性增强有密切的关系。     

心率变异性分析评价疼痛对自主神经活动的影响

本研究旨在探讨辣椒素疼痛模型建立的可行性和心率变异性(HRV)分析用于疼痛评价的可能性,并对辣椒素致痛过程中志愿者的自主神经活动性的变化进行研究。本研究对30名健康志愿者进行辣椒素刺激,记录刺激后的视觉模拟量表(VAS)评分及其刺激前后的心电信号及HRV分析指标,包括时域分析指标、频域分析指标、非线性分析指标。实验结果表明辣椒素导致人体疼痛的过程中,志愿者的自主神经活性升高,其中交感神经活性升高明显,在HRV上有明显变化。由此可见,辣椒素疼痛模型的建立是可行的。在进一步的实验中HRV分析有望作为定量评价疼痛的参考指标之一。     

低体温与心率变异性和血压变异性的关系

目的: 研究低体温与自主神经功能变化的关系。方法: 采用体表物理降温法逐步降低直肠温度,直肠温度变化范围为19-37 ℃。分别记录不同直肠温度下大鼠动态心电和血压信号。应用心率变异性和血压变异性分析系统评价低体温对心率变异性和收缩压变异性的影响。结果: 心率变异分析表明，直肠温度下降到29 ℃以下,R-R间期均延长（P<0.01）,提示心率明显降低;当直肠温度下降到19-21 ℃时,心率变异归一化低频功率降低（P<0.05）和归一化高频功率增加（P<0.05），而且自主神经的平衡向心迷走神经张力增强的方向发生了转移（P<0.05）。血压变异性分析表明，体温下降到31℃时与呼吸有关的归一化高频功率开始增加（P<0.01）；直肠温度下降到29 ℃以下(除27 ℃外),与呼吸有关的归一化高频功率增加（P<0.05或P<0.01），同时自主神经的平衡也发生了改变（P<0.05）。结论： 随着体温的降低，心血管迷走神经活性增加，自主神经的平衡向迷走神经张力增强的方向转移。低体温对血压变异性的影响敏感于心率变异性。     

大鼠实验性心肌缺血再灌注时心肌细胞凋亡的动态变化及意义

探讨大鼠心肌缺血再灌注时心肌细胞凋亡的动态变化及其与心肌缺血再灌注损伤的相互关系。结果显示假手术组与心肌缺血１５ｈ未见心肌细胞凋亡,但缺血３５ｈ或缺血３０ｍｉｎ再灌注ｌｈ已见有细胞凋亡,细胞凋亡出现明显早于细胞坏死。细胞凋亡指数（ＡＩ）随缺血或再灌注时间延长呈渐增趋势,分别以缺血４８．５ｈ（４９８％士１７．２７％）和缺血３０ｍｉｎ再灌注４８ｈ（３８．１５％±１３．２６％）最高。与心肌缺血组比较,心肌缺血再灌注组相同处理时间的大鼠的ＡＩ较低（Ｐ＜０．０５）。凋亡细胞主要位于心肌纤维收缩带区域及心肌梗死区周围。电镜示再灌注;０肌组织中有典型细胞凋亡形态改变。研究提示心肌细胞凋亡是持续性心肌缺血中早期心肌细胞死亡的主要形式,再灌注过程虽减少凋亡细胞数量,但却促进了不可逆损伤的心肌细胞的凋亡过程。     

冠心病患者心率变异性分析

目的研究冠心病患者心率变异（HRV）的变化规律及临床意义。方法选择50例无心律失常冠心病患者（冠心病组）、30例伴心律失常冠心病患者（心率失常组）与52例正常成人自愿者（正常组）进行24h动态心电图HRV指标比较研究。结果与正常组比较,冠心病患者SDNN、SDANN、RMSSD、PNN50和HF指标均降低,LF指标升高,具有显著差异。伴心律失常与无心律失常冠心病患者比较,HRV指标异常变化趋于恶化。结论冠心病患者心脏自主神经调节功能受到损害,迷走神经活性减弱,交感神经活动占优势。     

巴金森病与多系统萎缩患者的交感神经皮肤反应研究

目的：研究原发性巴金森病（IPD）与多系统萎缩（MSA）交感神经皮肤反应（SSR）,以探讨它们自主神经功能障碍的差异。方法：对31例IPD、17例MSA和83位正常人的SSR结果比较,分析PD组和MSA组SSR异常特征和与病程、自主神经症状的相关性。结果：MSA组SSR异常率（76％）显著高于IPD组（45％）,以双侧异常多见。3年内病程的SSR异常率为73％,并与自主神经症状相关。IPD组SSR异常与病程显著相关,与自主神经症状无完全对应关系,SSR异常更多见于震颤侧。结论：MSA广泛而严重的自主神经系统受累可能是SSR异常显著有别于IPD的基础。SSR异常出现早,呈双侧改变,且与自主神经症状有对应关系,则更多提示MSA的可能。     

丝瓜络对小鼠心肌缺血性损伤的预防效应

目的：探讨中药丝瓜络（RLF）对小鼠心肌缺血性损伤的防治作用。 方法： 预先给予昆明小鼠166.7，333.3，666.7 g/L的丝瓜络煎剂0.01 mL/g灌胃，每日2次，1周后腹腔注射垂体后叶素30 U/kg诱发急性心肌缺血，观察心电图变化，检测血清乳酸脱氢酶（LDH）、心肌组织中丙二醛（MDA）含量和超氧化物歧化酶（SOD）活性的改变。 结果： 各种剂量RLF均能降低垂体后叶素所引起的小鼠心电图中T波增高幅度及抑制心率减慢；并显著降低心肌缺血后造成的血清LDH以及心肌组织内MDA含量的增高，增加心肌组织中SOD活性。 结论： RLF对急性缺血心肌有明显的保护作用，其作用机制可能与抑制心肌脂质过氧化，增强其抗氧化能力有关。     

Characterization of QT and RR interval series during acute myocardial ischemia by means of recurrence quantification analysis

This study is aimed to investigate the nonlinear dynamic properties of the fluctuations in ventricular repolarization, heart rate and their correlation during acute myocardial ischemia. From 13 ECG records in long-term ST-T database, 170 ischemic episodes were selected with the duration of 34 s to 23 min 18 s, and two 5-min episodes immediately before and after each ischemic episode as non-ischemic ones for comparison. QT interval (QTI) and RR interval (RRI) were extracted and the ectopic beats were removed. Recurrence quantification analysis (RQA) was performed on QTI and RRI series, respectively, and cross recurrence quantification analysis (CRQA) on paired normalized QTI and RRI series. Wilcoxon signed-rank test was used for statistical analysis. Results revealed that the RQA indexes for QTI and HRI series had the same changing trend during ischemia with more significantly changed indexes in QTI series. In the CRQA, indexes related to the vertical and horizontal structures in recurrence plot significantly increased, representing decreased dependency of QTI on RRI. Both QTI and RRI series showed reduced complexity during ischemia with higher sensitivity in ventricular repolarization. The weakened coupling between QTI and RRI suggests the decreased influence of sinoatrial node on QTI modulation during ischemia.     

Atrial ganglionated plexi stimulation may be an effective therapeutic tool for the treatment of heart failure

An autonomic imbalance, i.e., increased sympathetic tone and/or decreased parasympathetic tone is a critical characteristic of heart failure, which is associated with progressive ventricular remodeling, ventricular arrhythmia generation and disease progression. Increasing cardiac parasympathetic tone by vagus nerve stimulation has been shown to significantly improve heart failure symptoms, hemodynamics, left ventricular function and quality of life. However, cervical surgery is needed to position vagal stimulation electrode and vagus nerve stimulation may also cause some undesired side effects. Our recent studies showed that ablation of the main atrial ganglionated plexi (GP) facilitated the occurrence of ventricular arrhythmias in acute myocardial ischemic heart while low-intensity atrial GP stimulation inhibited the occurrence of ventricular arrhythmias during acute myocardial ischemia and ischemia reperfusion. Based on these results, we hypothesize that atrial GP stimulation may ameliorate autonomic dysfunction in heart failure, inhibit heart failure progression and improve heart failure prognosis.     

病毒性心肌炎患儿心率变异指标变化的临床研究

目的研究病毒性心肌炎患儿心率变异(HRV)的变化特点。方法:选用74例儿童为研究对象,分为正常对照组和心肌炎组,进行心率变异检测分析。结果:与正常儿童比较,心肌炎患儿心率增快,心率变异指标降低。结论:心肌炎患儿HRV降低源于心肌缺血及相关炎性因子作用导致心脏自主神经系统总体功能受损,其病变对副交感神经系统的影响比交感神经系统更明显。     

Characterization of the nonlinear content of the heart rate dynamics during myocardial ischemia

We develop a method to quantify the changes in heart rate dynamics during local myocardial ischemia induced by a percutaneous transluminal coronary angioplasty procedure (PTCA). The method introduces an index measuring the nonlinear content of the beat-to-beat (RR) time series by using nonlinear time series techniques such as surrogate data analysis and average mutual information.The index is applied to RR data from 67 subjects obtained before, during, and after the ischemic period and shows an increase in the nonlinearity of the cardiac control dynamics during ischemic and reperfusion stages. The nonlinear index is also used to characterize the effects of performing the coronary occlusion at different arteries and distances. We observe that the effect of ischemia becomes larger as the occlusion distance is reduced, and that most of the changes in the nonlinear content of the dynamics occur at long time scales typically related to sympathetic modulation of the cardiac rhythm (6–25 s).     

Heart rate, magnitude and duration of ST-segment depression in symptomatic and asymptomatic episodes of myocardial ischemia in patients with coronary artery disease recorded by Holter

In the group of 85 patients with coronary artery disease the exercise and 24-hour ambulatory electrocardiograms were recorded in order to analyse the frequency of asymptomatic episodes of myocardial ischemia and to determine differences between symptomatic and asymptomatic episodes of myocardial ischemia. All patients had ischemic ST-segment depression (greater than or equal to 1 mm) on the exercise electrocardiogram. During exercise testing, 23 (27%) patients had ST-segment depression without anginal pain or dyspnea. On the 24-hour ambulatory electrocardiogram transient episodes of myocardial ischemia were found in 50 (58.8%) patients. In 16 patients all episodes were asymptomatic, in 9 all episodes were symptomatic, and in 25 patients some episodes were symptomatic and some asymptomatic. During a 24-hour electrocardiogram in 25 patients with both types of ischemia, 175 transient episodes of myocardial ischemia were recorded. Most of them (125, i.e. 71.4%) were asymptomatic. The heart rate in symptomatic and asymptomatic episodes was similar. The magnitude of ST-segment depression in symptomatic episodes was higher than in asymptomatic episodes (P less than 0.01). There was not significant difference in the duration of the two types of myocardial ischemia. This study suggests: 1. During daily activities, in patients with the positive exercise test, asymptomatic episodes of myocardial ischemia are more frequent than symptomatic episodes. 2. The magnitude of ST-segment depression is the main factor in the determination of the presence of anginal pain.     

Binary symbolic dynamics classifies heart rate variability patterns linked to autonomic modulations

Symbolic dynamics derived from heart rate variability (HRV) is able to reflect changes of cardiac autonomic modulations on short time scales in spite of the considerable reduction of information involved. However, the link between the appearance of specific symbolic patterns and the activity of the autonomic nervous system has not yet been elucidated. In this study, we investigate the symbolic dynamics that reflect acceleration (='1') and deceleration (='0') of the instantaneous heart rate. The resulting binary series is analyzed with respect to the regularity of binary patterns of length 8 using Approximate Entropy (ApEn). Binary patterns were grouped according to the level of their regularity as assessed by ApEn. ECG recordings were obtained from 17 healthy subjects during graded head-up tilt (0, 15, 30, 45, 60, 75, and 90°). The linear correlation (Spearman correlation coefficient) between tilt angle and the occurrence of binary patterns was evaluated. The results show that regular binary patterns occurred more often with increasing tilt angle whereas the occurrence of some irregular patterns decreased. Some binary patterns did not show a change of occurrence during tilt. When compared to the results of spectral analysis, regular binary patterns reflect sympathetic modulations whereas irregular binary patterns reflect parasympathetic modulations. The parameters derived from binary symbolic dynamics reflect changes of autonomic modulations during graded head-up tilt and are not fully correlated to the spectral markers of HRV.     

自主神经对心脏房室传导调节的动态分析

尽管自主神经对心脏房室传导的作用报道很多，但自主神经对房室传导的动力学特性仍未被揭示。本实验通过模板匹配方法从His束电图检测A、H、V波并测量两心房间期(AA)、心房波与H波间期(AH)、H波与心室波间期(HV)和心房波与心室波间期(AV)，通过白噪声技术动力性刺激迷走神经、交感神经或心房起搏时AV间期的传递函数变化，研究动态自主神经刺激对房室传导的动态调节。结果如下：AV间期对迷走神经刺激呈一阶低通滤波性质，起搏时AV间期增益(13．2％)较未起搏时明显增高(4．6％，P＜0．05)；AV间期对交感神经刺激呈二阶低通滤波性质，起搏时AV间期增益(46％)较未起搏时明显增高(32％，P＜0．05)；动力性起搏心房，从间期与AV间期呈良好负相关。因此认为：(1)AV间期对迷走神经或交感神经刺激均呈现出低通滤波性质。(2)心脏的房室传导时间与心动周期长度呈线性负相关。心率的改变增强交感或迷走神经对房室传导的动力性作用，心率对房室传导的作用在迷走刺激时较交感刺激时强。这在房室传导对自主神经动力性调节的反应时保持相对稳定具有重要的生理意义。     

Sympathetic nervous system representation in time and frequency domain indices of heart rate variability

This study evaluated the contributions of sympathetic and parasympathetic modulation to heart rate variability during situations in which vagal and sympathetic tone predominated. In a placebo-controlled, randomized, double blind blockade study, six young healthy male individuals received propranolol (0.2?mg?·?kg^?1), atropine (0.04?mg?·?kg^?1), propranolol plus atropine, or placebo infusions over 4 days. Time-domain indices were calculated during 40?min of rest and 20?min of exercise at 70% of maximal exercise intensity. Spectrum analysis, using fast Fourier transformation, was also performed at rest and during the exercise. The time-domain indices standard deviation of R-R intervals, mean of the standard deviations of all R-R intervals for all 5-min segments, percentage of number of pairs of adjacent R-R intervals differing by more than 50?ms, and square root of the mean of the sum of squares of differences between adjacent R-R intervals were reduced after atropine and propranolol plus atropine. Propranolol alone caused no appreciable change in any of the time-domain indices. At rest, all spectrum components were similar after placebo and propranolol infusions, but following parasympathetic and double autonomic blockade there was a reduction in all components of the spectrum analysis, except for the low:high ratio. During exercise, partial and double blockade did not change significantly any of the spectrum components. Thus, time and frequency-domain indices of heart rate variability were able to detect vagal activity, but could not detect sympathetic activity. During exercise, spectrum analysis is not capable of evaluating autonomic modulation of heart rate.     

Low-frequency power of heart rate variability is not a measure of cardiac sympathetic tone but may be a measure of modulation of cardiac autonomic outflows by baroreflexes

Power spectral analysis of heart rate variability has often been used to assess cardiac autonomic function; however, the relationship of low-frequency (LF) power of heart rate variability to cardiac sympathetic tone has been unclear. With or without adjustment for high-frequency (HF) power, total power or respiration, LF power seems to provide an index not of cardiac sympathetic tone but of baroreflex function. Manipulations and drugs that change LF power or LF:HF may do so not by affecting cardiac autonomic outflows directly but by affecting modulation of those outflows by baroreflexes.     

Intermittent arm ischemia induces vasodilatation of the contralateral upper limb

Intermittent arm ischemia before percutaneous coronary intervention induces remote ischemic preconditioning (RIPC) and attenuates myocardial injury in patients with myocardial infarction. Several studies have shown that intermittent arm ischemia increases coronary flow and is related to autonomic nerve system. The aim of this study was to determine whether intermittent arm ischemia induces vasodilatation of other arteries and to assess changes in the autonomic nerve system during intermittent arm ischemia in humans. We measured change in the right brachial artery diameter during intermittent left arm ischemia through three cycles of 5-min inflation (200 mmHg) and 5-min deflation of a blood-pressure cuff using a 10-MHz linear array transducer probe in 20 healthy volunteers. We simultaneously performed power spectral analysis of heart rate. Ischemia-reperfusion of the left arm significantly dilated the right brachial artery time-dependently, resulting in a 3.2 ± 0.4% increase after the 3rd cycle. In the power spectral analysis of heart rate, the high-frequency domain (HF), which is a marker of parasympathetic activity, was significantly higher after the 3rd cycle of ischemia-reperfusion than baseline HF (P = 0.02). Intermittent arm ischemia was accompanied by vasodilatation of another artery and enhancement of parasympathetic activity. Those effects may play an important role in the mechanism of RIPC.