血管紧张素Ⅱ对大鼠心率和心率变异的影响

目的研究血管紧张Ⅱ(AngⅡ)对大鼠心率以及变异(HRV)的影响及其机制。方法大鼠股静脉注射5%葡萄糖然后输注AngⅡ作为实验组,股静脉注射AT1受体(Angiotensin Ⅱ receptorⅠ)阻断剂氯沙坦(Losartan,LOS)然后输注AngⅡ作为对照组。对各组大鼠进行心电图(ECG)和BP(血压)数据的采集,对各组大鼠HRV的频域指标进行分析。结果与实验组相比,对照组频域指标低频(LF)和LF/HF明显降低而高频(HF)明显升高(P<0.05),而心率(HR)没有显著变化(P>0.05)。结论 AngⅡ对大鼠的HRV作用是通过AT1受体实现的。     

放松训练对脑电、心率变异及情绪的影响

目的：观察放松训练对受试者脑电、心率变异、情绪、肌电和皮肤末梢循环的影响，以及以上各因素之间的关系，探讨放松训练对抗精神紧张、改善心身健康的心理生理机制。方法：将60名大学生分为实验组和对照组；实验组集体接受放松训练2个月，对照组不接受任何放松训练；两组实验期间同时经历考试应激过程。比较实验前后两组的心率变异，并用心理测验量表（SCL－90、SRHMS和PSQI）对其情绪进行评估，同时测定2个月后两组的脑电变化。最后，以脑电指标中的额α指数为因变量，进行回归分析。结果：2个月后，与对照组比较，实验组的脑电α指数及脑电相干函数增高、心率变异中低频／高频比值降低（P＜0．05）、RR间期散点图形状得分升高（P＜0．01），SCL－90总分降低（P＜0．01）。结论：放松训练对大学生精神紧张有一定缓解作用。     

岛叶的功能及对心率变异性的影响

心率变异性作为判断心脏自主神经状态的无创性指标常被用来定量分析自主神经的功能状态，其时域及频域降低与恶性心律失常、心功能不全，乃至心源性猝死等有关。人类的岛叶是控制交感神经和副交感神经介导的心血管调节最重要的皮层区域，多数学者在临床实践中发现，岛叶病变会导致心血管功能紊乱及自主神经功能状态的变化，因此岛叶与心脏功能之间的联系倍受重视。     

癫的电刺激治疗

在癫(癎)患者中,约有1/3为难治性癫(癎)患者,尽管有很多新的抗癫(癎)药物可以供临床医生选择,但是难治性癫(癎)的发病率并没有下降.应用两种抗癫(癎)药物而无法有效控制发作者,即使再加用其它抗癫(癎)药物也不能控制发作.有研究表明,癫(癎)患者,尤其是难治性癫(癎)患者,其生活质量和社会功能都受到严重的损害,包括低自卑心理、严重的抑郁、生活不能自理等,也给社会和家庭带来了严重的负担.相对于传统的药物治疗,迷走神经刺激、中枢神经系统电刺激等非药物疗法给难治性癫(癎)患者带来了新的希望.……     

基于HHT边际谱熵和能量谱熵的心率变异信号的分析方法

基于希尔伯特-黄变换(HHT)理论,依据广义信息熵的概念,提出基于HHT边际谱熵和能量谱熵的概念和熵分析方法。对常规信号和混沌时间序列信号进行复杂性研究,结果表明本方法在刻画信号复杂度变化、抗脉冲干扰方面优于Lempel-Ziv复杂度和功率谱熵方法。将其应用于MIT-BIH标准数据库的实际心率变异(HRV)信号分析,结果显示HHT边际谱熵和能量谱熵能从HRV信号中敏感地检测出生理和病理状态的变化,统计学分析优于传统的功率谱熵方法,为临床HRV信号及其他复杂生理信号的分析提供一种有效的分析方法。     

神经电刺激下的人体增强研究进展

近年来,许多研究探索人类记忆、学习、情绪调控等认知功能、感知功能、运动功能的神经电刺激增强。脑机接口可用作更精细化的神经电刺激,它的信息读写性能提升也得到研究。非侵入式刺激以经颅直流电刺激(tDCS)为代表,实施较为便捷,但是在长期有效性和刺激精度方面需要进一步提升。侵入式刺激方式以脑深部电刺激(DBS)、迷走神经刺激(VNS)为代表,已经在临床上取得了广泛的认可和应用,刺激具备高精度特性,但是在增强方面的研究与应用上存在限制。对以上研究进展进行综述,并对人体增强研究的局限和发展趋势进行评论。     

癫(癎)的电刺激治疗

在癫癎患者中,约有1／3为难治性癫癎患者,尽管有很多新的抗癫癎药物可以供临床医生选择,但是难治性癫癎的发病率并没有下降。应用两种抗癫癎药物而无法有效控制发作者,即使再加用其它抗癫癎药物也不能控制发作。有研究表明,癫癎患者,尤其是难治性癫癎患者,其生活质量和社会功能都受到严重的损害,包括低自卑心理、严重的抑郁、生     

三叉神经电刺激治疗难治性癫癎的研究进展

癫癎是脑部神经元反复异常过度或同步性活动引起的神经系统疾病,可导致感觉、认知、心理等方面的改变,严重威胁人类的身心健康［1］。其患病率约为7‰,我国每年新发病的癫癎患者约80～90万,其中25％～30％转化为顽固性癫癎,抗癫癎药物治疗不能控制顽固性癫癎的发作,造成严重的家庭和社会负担［2‐3］。外科手术治疗也只对少数顽固性癫癎有效,有的甚至加重癫癎发作,并且出于费用昂贵等方面的原因而不能得到广泛应用。电刺激作为一种新的癫癎治疗手段为难治性癫癎患者带来了一种新的选择。     

经颅电刺激对大鼠脑梗死后运动功能恢复的影响

目的 :观察经颅皮层电刺激治疗对大鼠脑梗死后运动功能恢复的作用。方法 :选择12 0只SD成年雄性大鼠制作大脑中动脉闭塞 (MCAO)模型 ,将大鼠随机分为治疗组和对照组各 6 0只 ,治疗组在术后 3天给予经颅电刺激治疗 ,对照组术后不进行治疗 ,于术后第 1、2、3、4、5、6周末 ,分别以横木行走试验 (BWT)及运动诱发电位为指标评价大鼠运动功能恢复情况。结果 :经颅磁刺激治疗的大鼠 ,运动功能较对照组明显改善 (P <0 .0 1)。第 6周末治疗组患侧MEP波幅与潜伏期基本恢复正常 ,而对照组患侧MEP波幅仅恢复到 73.5 % ,潜伏期仍有所延长 ,两组相比有显著差异 (P <0 .0 5 )。结论 :经颅电刺激可以促进急性脑梗死大鼠瘫痪肢体运动功能的恢复 ,其机理可能与电刺激直接兴奋大脑皮层的运动中枢有关     

正常人短时心率变异性指标在长时序列中的分布特性及其年龄的影响

无创的心率变异性(HRV)检测所反映的自主神经状态可受生理、病理和心理等因素影响。提出研究短时HRV分析指标在长时序列中的分布特性,并探讨在正常人中随年龄可能发生的变化。将THEW中Normal子数据库中年龄大于18岁的Holter数据(n=177)分为5个年龄组(18≤y≤25, n=35; 25< y≤35, n=44; 35< y≤45, n=41; 45< y≤55, n=34; y >55, n=23)。利用5 min的滑动窗口、2.5 min的步长,计算每个滑动窗的RR间期均值(MRRI)、LF/HF和短时分形尺度指数(α₁),然后基于长时序列,分别计算MRRI和LF/HF,以及MRRI和α₁这两种配对的Spearman相关系数,并在各组内统计相关性良好人数的百分占比。然后,以具有正常作息时间和数据长度为筛选标准,从177名正常人中筛选出93名25<y≤65岁的受试数据,并以10岁为间隔分为4个年龄组,计算每人各个2 h时段中的各5 min滑动窗(2.5 min步长)的指标均值(EM_MRRI、EM_LF/HF和EM_α₁)。结果表明,具有良好相关性的人数百分占比在18≤y≤55的年龄段保持高水平(94%～100%),但在年龄大于55岁后急剧下降(MRRI vs LF/HF: 78.26%; MRRI vs α₁: 65.22%)。对于清晨最低EM_MRRI时段,其EM_MRRI、EM_LF/HF和EM_α₁在各年龄组均不存在显著差异(P>0.05)),但在其他时段这些参数则可能存在显著差异。随着可穿戴技术的发展,长时心率序列(RR间期序列)的可获得性大幅度提高,该研究结果对于拓展长时序列的HRV分析方法可提供新的思路。     

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.     

Effect of mobile phone radiation on heart rate variability

The rapid increase in the use of mobile phones (MPs) in recent years has raised the problem of health risk connected with high-frequency electromagnetic fields. There are reports of headache, dizziness, numbness in the thigh, and heaviness in the chest among MP users. This paper deals with the neurological effect of electromagnetic fields radiated from MPs, by studies on heart rate variability (HRV) of 14 male volunteers. As heart rate is modulated by the autonomic nervous system, study of HRV can be used for assessing the neurological effect. The parameters used in this study for quantifying the effect on HRV are scaling exponent and sample entropy. The result indicates an increase in both the parameters when MP is kept close to the chest and a decrease when kept close to the head. MP has caused changes in HRV indices and the change varied with its position, but the changes cannot be considered significant as the p values are high.     

咖啡摄入前后心率变异性的对比研究

目的研究中等剂量咖啡摄入对青年受试者心率变异性的影响,明确咖啡对心脏自主神经活性的作用。方法无咖啡因摄入习惯的16名健康青年受试者(身高167 cm±7.2 cm、体重61.3 kg±6.3kg、年龄24.9岁±2.8岁)参与本项研究,在摄入含6 mg/kg咖啡因的咖啡饮品后,于8:40~10:45应用动态心电图记录仪(Holter)进行咖啡摄入前后心电信号的采集及心率(heart rate,HR)和心率变异性指标的分析。心率变异性指标包括R-R间期标准差(SDNN)、相邻R-R间期差值的均方根值(r MSSD)、相邻的R-R间期之差大于50 ms的心搏数占总心搏数的百分比(PNN50)、标化低频(normalized low frequency power,LFnorm)、标化高频(normalized high frequency power,HFnorm)、低频功率(low frequency,LF)与高频功率(high frequency,HF)的比值(LF/HF)。结果饮用咖啡后,心率、心率变异性指标均发生改变且具有统计学意义,HR、LFnorm和LF/HF分别降低了7.5%、17%和35%。r MSSD、PNN50和HFnorm分别提高了82%、80%和58%。其中HR及LF/HF随着时间的变化趋势最明显。HRV参数在饮用咖啡前后的差值ΔLF与ΔHF,ΔLF与ΔLF/HF均显著相关,相关系数为-0.980和0.903。结论中等剂量咖啡可引起心率变异性的改变和心率的降低,抑制交感神经活性,提高副交感神经活性。     

Assessment of heart rate variability derived from finger-tip photoplethysmography as compared to electrocardiography

Heart rate variability (HRV) is traditionally derived from RR interval time series of electrocardiography (ECG). Photoplethysmography (PPG) also reflects the cardiac rhythm since the mechanical activity of the heart is coupled to its electrical activity. Thus, theoretically, PPG can be used for determining the interval between successive heartbeats and heart rate variability. However, the PPG wave lags behind the ECG signal by the time required for transmission of pulse wave. In this study, finger-tip PPG and standard lead II ECG were recorded for five minutes from 10 healthy subjects at rest. The results showed a high correlation (median = 0.97) between the ECG-derived RR intervals and PPG-derived peak-to-peak (PP) intervals. PP variability was accurate (0.1 ms) as compared to RR variability. The time domain, frequency domain and Poincaré plot HRV parameters computed using RR interval method and PP interval method showed no significant differences (p < 0.05). The error analysis also showed insignificant differences between the HRV indices obtained by the two methods. Bland-Altman analysis showed high degree of agreement between the two methods for all the parameters of HRV. Thus, HRV can also be reliably estimated from the PPG based PP interval method.     

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.     

Comparison of finger plethysmograph to ECG in the measurement of heart rate variability

Two experiments compared finger plethysmograph (FP) to electrocardiogram (ECG) in providing accurate heart periods for use in heart rate variability (HRV) calculations. In Experiment 1, simultaneous ECG and FP recordings were taken from 16 healthy subjects at rest. In Experiment 2, 10 additional healthy subjects were recorded at rest and during the Stroop Color-Word Test. In both studies, high correlations were found between FP-derived and ECG-derived band variance for high and low frequency HRV at rest. But, during the Stroop task, correlations were strongly diminished. In addition, under both conditions, HRV measures were significantly higher using the FP signal. Thus, FP may be adequate for determining HRV at rest, but, for experimental use, ECG may still be recommended. Nonetheless, further studies that include test-retest reliability assessment of both data collection techniques are warranted before a more certain determination can be made.     

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。     

Automatic measurement of long-term heart rate variability by implanted single-chamber devices

Heart rate variability (HRV) measurement is an established technology for the assessment of cardiac autonomic status. Recently 24 h HRV has been shown to correlate with disease severity in heart failure. This potentially makes continuous 24 h HRV measurement suitable for monitoring of heart-failure patients. Day-to-day 24 h measurement of HRV is, in principle, feasible when implemented using implanted devices (pacemakers and defibrillators) used in patients who are predominantly in the sinus rhythm. However, a number of such devices used in heart-failure patients are single-chamber devices, in which the distinction between sinus rhythm beats and ectopic beats is problematic. The study investigates whether a reasonably accurate 24 h HRV measurement can be achieved by automatic algorithms, suitable for implementation using implanted devices, without the need for identification of ectopic beats. A set of 5321 nominal 24 h Holter recordings of cardiac patients are used. Each of the recordings contains at least one ectopic beat; approximately 30% of the recordings have more than 1% of ectopic beats. Conventional 24 h measures of HRV, that is the SDNN, HRV index, and SDANN indices, are obtained from each recording after elimination of the ectopic beats and are approximated by HRV measures computed by the same formulas without exclusion of the ectopic beats. The SDANN values are also approximated by the standard deviation of 5 min medians of all RR intervals (SDMRR measure). The errors introduced by including the ectopic beats in the HRV computation were evaluated using the Bland-Altman statistics and by Cohen's kappa statistics investigating the precision of identifying patients with depressed and preserved 24 h HRV. The SDNN measure is very sensitive to the quality of the RR interval sequence and cannot be reasonably used without distinction between sinus rhythm and ectopic beats. The HRV index measure is marginally more acceptable when used without ectopic elimination. The SDANN is rather insensitive, and its replacement by SDMRR values leads to relative errors in the region of 2-5% that are almost independent of the number of ectopic beats included. Even in recordings with a substantial proportion of ectopic beats, a practically acceptable (kappa > 0.9) identification of depressed and preserved SDANN values is possible without ectopic elimination. Thus, continuous monitoring of 24 h HRV is technically feasible within implanted devices, provided the SDANN measure is monitored and either computed from the sequence of all RR intervals or, potentially preferably, replaced by the SDMRR measure.     

Automatic measurement of long-term heart rate variability by implanted single-chamber devices

Heart rate variability (HRV) measurement is an established technology for the assessment of cardiac autonomic status. Recently 24 h HRV has been shown to correlate with disease severity in heart failure. This potentially makes continuous 24h HRV measurement suitable for monitoring of heart-failure patients. Day-to-day 24 h measurement of HRV is, in principle, feasible when implemented using implanted devices (pacemakers and defibrillators)_ ued in patients who are predominantly in the sinus rhythm. However, a number of such devices used in heart-failure patients are single-chamber devices, in which the distinction between sinus rhythm beats and ectopic beats is problematic. The study investigates whether a reasonably accurate 24h HRV measurement can be achieved by automatic algorithms, suitable for implementation using implanted devices, without the need for identification of ectopic beats. A set of 5321 nominal 24 h Holter recordings of cardiac patients are used. Each of the recordings contains at least one ectopic beat; approximately 30% of the recordings have more than 1% of ectopic beats. Conventional 24h measures of HRV, that is the SDNN, HRV index, and SDANN indices, are obtained from each recording after elimination of the ectopic beats and are approximated by HRV measures computed by the same formulas without exclusion of the ectopic beats. The SDANN values are also approximated by the standard deviation of 5 min medians of all RR intervals (SDMRR measure). The errors introduced by including the ectopic beats in the HRV computation were evaluated using the Bland-Altman statistics and by Cohen's kappa statistics investigating the precision of identifying patients with depressed and preserved 24 h HRV. The SDNN measure is very sensitive to the quality of the RR interval sequence and cannot be reasonably used without the distinction between sinus rhythm and ectopic beats. The HRV index measure is marginally more acceptable when used without ectopic elimination. The SDANN is rather insensitive, and its replacement by SDMRR values leads to relative errors in the region of 2–5% that are almost independent of the number of ectopic beats included. Even in recordings with a substantial proportion of ectopic beats, a practically acceptable (κ>0.9) identification of depressed and preserved SDANN values is possible without ectopic elimination. Thus, continuous monitoring of 24h HRV is technically feasible within implanted devices, provided the SDANN measure is monitored and either computed from the sequence of all RR intervals or, potentially preferably, replaced by the SDMRR measure.     

Effect of meal content on heart rate variability and cardiovascular reactivity to mental stress

Little is known about transient effects of foods and nutrients on reactivity to mental stress. In a randomized crossover study of healthy adults (n=20), we measured heart rate variability (respiratory sinus arrhythmia), blood pressure, and other hemodynamic variables after three test meals varying in type and amount of fat. Measurements were collected at rest and during speech and cold pressor tasks. There were significant postmeal changes in resting diastolic blood pressure (-4%), cardiac output (+18%), total peripheral resistance (-17%), and interleukin-6 (-27%). Heart rate variability and hemodynamic reactivity to stress was not affected by meal content. We recommend that future studies control for time since last meal and continue to examine effects of meal content on heart rate variability.