体位改变对Beagle犬心脏自主神经控制的影响

目的观察体位改变对Beagle犬心脏自主神经控制的影响。方法利用大动物无创生理遥测技术,监测清醒活动状态下雌性Beagle犬在静态姿势（lying、standing、sitting、hanging）和运动（walking）姿势下的心电图（ECG）,并用HRV功率谱分析其自主神经功能。结果在静态姿势下,Beagle犬RR间期（RRI）、RR间期的标准差SDNN（SDNN）、相邻RR间期差值平方和的均方根RMSSD（RMSSD）、相邻R-R间期差值〉50 ms的窦性个数占心搏总数的百分比pNNabs（50）（pNNabs（50））、TP总功率（TP）、VLF极低频功率（VLF）、标准化高频功率（HFnorm）均明显高于运动状态（P〈0.05,P〈0.01）,而心率（HR）、标准化低频功率（LFnorm）和低频功率/高频功率（LF/HF）平衡指数则明显低于运动状态（P〈0.05,P〈0.01）。结论不同体位姿势在静息状态下以迷走神经活动兴奋为主,相反,在运动状态下以交感神经活动兴奋为主;体位姿势改变能引起心率的变化,必然影响心脏自主神经控制能力,其主要取决于迷走神经活动强弱有关,且导致LF/HF均衡性的破坏。     

五指山小型猪高脂血症模型的心脏自主神经功能变化

目的观察五指山小型猪高脂血症模型的心脏自主神经功能的动态变化,探讨血脂异常对自主神经功能的影响和与昼夜的关系。方法利用高脂饮食诱发五指山小型猪高脂血症,造模后,每2周一次测定小型猪TG、TC、HDL-C和LDL-C和监测动态心电图,并进行24 h和昼夜心率变异性（HRV）分析,以评估小型猪的心脏自主神经功能。结果高脂饮食2周后五指山小型猪血清TC、HDL-C、LDL-C水平均显著升高（P〈0.01）,TG水平亦在高脂饮食后6周显著升高（P〈0.05）,其中,TC、LDL-C在高脂饮食0～4周时呈快速上升,在4～6周达到高峰,8～10周基本稳定并维持在一定水平;HDL-C在高脂饮食0～2周迅速上升并达到高峰,2～10周基本稳定。HRV参数分析结果,时域指标（RRI、SDNN、RMSDD、SDANN、PNN50、SDANN index、STV、LTV）和频域指标（VLF、LF、HF和TP）均渐进性显著降低（P〈0.05,P〈0.01）,LF/HF升高（P〈0.05）,夜间HRV参数变化程度均高于白天;相关分析显示HRV各参数与TC、LDL-C、TC/HDL-C、LDL-C/HDL-C具有显著的相关性（P〈0.05,P〈0.01）,经多元线性逐步回归分析发现,SDNN与TC、LDL-C、TC/HDL-C、LDL-C/HDL-C比值的相关性依次为0.673、0.672、0.665、0.681。结论高脂饮食诱发五指山小型猪高脂血症的血脂异常可引起自主神经功能的下降和紊乱,自主神经功能的紊乱程度与高血脂状态的持续时间有关;血脂异常所致心血管疾病的危险程度夜间高于白天;HRV降低与TC、LDL-C、TC/HDL-C和LDL-C/HDL-C比值升高呈一定的依赖性,SDNN降低可作为预测高脂血症引发心血管病风险的独立相关指标。     

正常人体RR间期频谱分析及其在冷刺激时的变化

测定了96名健康人安静状态及冷刺激时的ECG,通过微机处理描出RR间期(RRI)变化的频谱曲线。计算和比较不同性别、年龄的被试者在安静及冷刺激时的RRI总变异性(TV)、低频成分(LF)、高频成分(HF)以及LF/HF比值。结果显示安静时男性总变异性为1312.33±170.97(ms)~2,LF/HF为1.52±0.18;女性分别为1653.33±197.29(ms)~2及1.17±0.21。男女之间无明显差异。≥40岁组与≤39岁组比较则可见前者TV较小、LF较高、HF较低及LF/HF比值较大。冷刺激后男性TV增加,P<0.01;LF/HF比值增大,P<0.001。女性冷刺激后TV也增加,但P>0.05;LF/HF比值增大,P<0.05。作者认为RRI频谱测定可作为植物神经功能评估的指标,可用于临床疾病的研究。     

清醒高血压大鼠心率变异分析的动物模型建立

目的：研究两种不同血浆肾素水平高血压大鼠心率变异的变化,进而探讨肾素。血管紧张素系统（RAS）影响心率变异（HRV）的机制。方法：制备两种高血压大鼠模型,采集其连续心电图数据。分析HRV的变化。并测定血浆血管紧张素Ⅱ（AngⅡ）的浓度。结果：肾性高血压大鼠血浆AngⅡ明显升高（P〈0．01）,心率变异频域指标中TP（总功率谱）、VLF（极低频功率）、LF（低频功率）和HF（高频功率）明显降低,LF／HF（低高频比）升高;DOCA-盐型高血压大鼠血浆AngⅡ水平明显降低,TP、VLF、LF和HF也明显降低。LF／HF比值升高。结论：两种不同血浆肾素水平的高血压大鼠交感和迷走神经均受损,同时交感神经活性相对占优势;提示肾素血管紧张素系统是通过脑内RAS的激活而影响HRV,不是循环RAS的外周作用。     

迷走神经在心率变异性中的作用

采用功率谱和近似熵 (approximateentropy ,ApEn)的方法 ,分析清醒家兔在双侧迷走神经保留 ,右、左侧迷走神经切断以及双侧迷走神经同时切断时心搏间期 (RRI)的变化。结果显示 :双侧迷走神经保留时功率谱中高频功率 (HF)、低频功率 (LF)及ApEn值均高于双侧及单侧迷走神经切断时 (P <0 0 5 ) ,LF/HF比值最小 ;切断单侧迷走神经 ,ApEn变小 ,LF/HF比值在右侧迷走神经切断时增大 ,而切断左侧迷走时LF/HF比值无明显变化 ;双侧迷走神经切断后LF/HF比值最大 ,ApEn最低。结果表明 :心率变异主要由迷走神经调节 ,右侧迷走神经起主要作用 ;传统心率变异性测量方法与非线性方法所得结果一致     

高血压病不同级别心功不全的自主神经功能变化及相关性研究

目的通过动态心电监护下心率变异性(HRV)分析自主神经功能对高血压病不同级别心功能不全的HRV变化。方法应用动态心电图和无创性心功能测定高血压病不同级别心功能不全的心率变异性的结果进行比较。结果发现高血压病不同级别心功能不全的患者随心功能损害的加重心率变异时域参数SDNN、SDRNN、RMSSD、PNN50和频域参数TP、VLF、LF、HF、LF/HF均明显降低,且有统计学差异。结论自主神经功能损害在高血压病不同级别的心功能不全患者起着重要的作用。     

不同负重量站立30 min对健康青年心脏自主神经功能的影响

目的：本研究评估不同负重量（0 kg、27.5 kg和50 kg）站立30 min对心脏自主神经功能的影响。方法：采用随机交互设计,24名健康男性受试者完成3次30 min静止站立,分别记录RR间期：包括安静状态5 min（卧位）,静态站立30 min,站立后恢复期5 min（卧位）,进行相应心率变异（HRV）分析。结果：与安静状态相比,站立中HR增加（P < 0.05）,RMSSD降低（P < 0.05）,负重量增加,SDNN、SDNN/HR和LF呈下降趋势,HF降低（P < 0.05）,LF/HF增加（P < 0.05）。与负重0 kg和27.5 kg相比,负重50 kg E-POCPeak和TRIMP增加（P < 0.05）。恢复期,HR下降,但未能恢复至安静水平;RMSSD恢复至安静水平,SDNN增加（P < 0.05）;负重50 kg,HR均高于负重0 kg和27.5 kg（P < 0.05）。结论：急性静力性30 min站立,心脏自主神经功能发生调整,随着负重量增加,整体HRV呈下降趋势,5 min恢复期,交感神经活性处在较高水平。不同负重状态下整体HRV变化相似。     

术前应用长托宁对老年患者心率变异性的影响

目的：探讨长托宁对老年患者心率变异性的影响,为长托宁作为术前药提供理论依据。方法：60例ASAII~III级老年患者随机分成阿托品组（A组）和长托宁组（B组）,静脉注射阿托品或长托宁0.01 mg/kg。观察注药前、注药后1、3、5、10、20及30min各组心率（HR）、心率变异总功率（TP）、低频（LF）、高频（HF）、心率变异性（HRV）的改变。结果：与A组相比,B组注药后1、3、5、10、20 min时HR均降低（P〈0.05）,1、3 min,TP降低（P〈0.05）,5、10、20、30 minTP升高（P〈0.01）,3、5、10、20、30 min,LF、HF均升高（P〈0.05或P〈0.01）。结论：长托宁对老年患者心率变异性影响较小,更适合术前用药。     

LF、HF与LF/HF在心率变异性分析中的应用与争议

心率变异性(heart rate variability, HRV)指连续正常心动周期的微小差异，是评估自主神经调节功能的重要指标。尽管HRV的LF(low frequency)、HF(high frequency)、LF/HF等频域指标被广泛用于评估交感神经系统与副交感神经系统的活性及其两者的相互调节作用，然而它们作为衡量自主神经系统功能指标的有效性一直受到质疑。本研究剖析了有关LF、HF与LF/HF等频域指标意义的不同观点，探讨了其作为评估自主神经系统功能的合理性与有效性。本研究认为，LF虽然受到交感神经活动的控制，但由于同时受迷走神经活动等其他因素的影响，且此影响程度较大，不建议单独使用LF以反映交感神经系统的活动；HF主要受心脏迷走神经的控制，能够较准确的反映迷走神经系统活动；LF/HF在一定程度上能够反映自主神经系统的调节作用，但由于存在非线性关系和其他因素的影响，LF/HF这一指标并不精准。     

电刺激迷走神经对蟾蜍心率和心率变异的影响

目的:观察不同频率迷走神经刺激对蟾蜍离体心脏的心率及心率变异的影响。方法:将蟾蜍心脏和右侧迷走交感干离体后,以不同频率电刺激神经,记录心电图曲线并作心率变异性(HRV)分析。结果:交感神经阻断后,电刺激迷走交感干,心率(HR)显著下降(P0.01),全部正常心动周期的标准差(SDNN)和相邻正常心动周期差值的均方根(RMSSD)显著升高(P0.01),不同频率刺激组之间没有明显差异;与对照组相比,各指标变化较大;给药组0.2Hz时高频(HF)显著升高(P0.01),低频/高频比值(LF/HF)明显降低(P0.05),0.8Hz时HF和LF/HF接近刺激前水平。结论:一定范围内增加刺激频率,迷走神经降低心率的作用增强;没有交感神经调节条件下的迷走神经对心率和心率变异的调节可能存在不同的机制。     

Power spectral analysis of heart rate variability for assessment of diurnal variation of autonomic nervous activity in miniature swine.

BACKGROUND AND PURPOSES: The purpose of the study was to document diurnal variation of autonomic nervous functions by use of power spectral analysis of heart rate (HR) variability. METHODS: To clarify characteristics of power spectral analysis of HR variability, electrocardiogram (ECG), blood pressure (BP), and respiratory (Resp) waveform simultaneously were recorded. RESULTS: Two major spectral components were examined at low (LF)- and high (HF)-frequency bands for HR variability. Coherence between HR and Resp variabilities and HR and BP variabilities was maximal at approximately 0.14 and 0.03 Hz, respectively. On the basis of these data, two frequency bands of interest--LF (0.01 to 0.07 Hz) and HF (0.07 to 1.0 Hz)--were defined. Autonomic blockade studies indicated that the parasympathetic system mediated the HF and LF components, whereas the sympathetic system mediated only the LF component; HR had a diurnal pattern. The LF and HF bands in the dark phase tended to be higher than those in the light phase. The LF-to-HF ratio had a diurnal pattern similar to that of the HR. CONCLUSION: Parasympathetic nervous activity in miniature swine may be predominant in the dark phase. The characteristics of power spectra and diurnal variations of autonomic nervous functions are almost the same as those of humans. Therefore, miniature swine may be a useful animal model for future biobehavioral and pharmacotoxicologic studies.     

1,6--二磷酸果糖联合局部封闭Calot三角对胆囊切除术心率

目的：观察胆囊切除术围术期输注1,6--磷酸果糖联合术中局部封闭Calot三角对血流动力学及心率变异性的影响。方法：择期胆囊切除术患者40例,年龄28-67岁,ASA分级Ⅰ-Ⅱ级,分为对照组（n=20）和试验组,试验组（n=20）患者在切皮前静脉滴注1,6--二磷酸果糖,在胆囊牵拉前在Calot三角注射2%利多卡因5ml,选择全凭静脉麻醉（TIVA）,气管内插管,机控通气。分别于胆囊牵拉前5分钟（T0）、牵拉时（T1）、牵拉五分钟（T2）,牵拉十分钟（T3）监测两组患者心率变异性和血流动力学。结果：牵拉瞬间对照组和试验组,TP值降低（p〈0.05）;牵拉五分钟时,对照组MAP、HR、HFnu较牵拉前和牵拉时降低有显著差异（p〈0.01）,且LF/HF比值较其他时间点降低（p〈0.05）;试验组HR牵拉前和牵拉时降低有统计学意义（p〈0.05）。牵拉十分钟时,两组TP较牵拉前降低有统计学意义（p〈0.05）;对照组MAP、HR较牵拉前和牵拉时降低有统计学意义（p〈0.05）。结论：切皮前静脉滴注1,6--二磷酸果糖联合局部封闭Calot三角对心率变异性和血流动力学影响小,可降低胆心反射对自主神经功能的影响。     

The nature of very low frequency component of the heart rate variability and the role of sympathetic-parasympathetic interactions

A method of separate monitoring "instant" changes of the VLF, LF and HF power spectral components of heart rate variability, has been developed. The power of the LF and HF spectral components were proved to be continuously changing. The period of these power fluctuations could stay within 15 to 150 sec. Comparison of the heart rate variability spectrum with LF and HF spectral components power fluctuations' spectrums has shown that the frequencies of the LF and HF spectral components power fluctuations stay within the VLF range. The co-operative spectrum form of these fluctuations repeats the form of the VLF peak. In cases when the LF and HF spectral components power fluctuations' periods do not coincide, VLF has two peaks. The frequency of one VLF peak coincides with frequency of the HF power fluctuations, and the frequency of another--with the frequency of LF power fluctuations.     

Heart Rate Variability Is Associated with Exercise Capacity in Patients with Cardiac Syndrome X

Heart rate variability (HRV) reflects the healthiness of autonomic nervous system, which is associated with exercise capacity. We therefore investigated whether HRV could predict the exercise capacity in the adults with cardiac syndrome X (CSX). A total of 238 subjects (57±12 years, 67.8% men), who were diagnosed as CSX by the positive exercise stress test and nearly normal coronary angiogram were enrolled. Power spectrum from the 24-hour recording of heart rate was analyzed in frequency domain using total power (TP) and spectral components of the very low frequency (VLF), low frequency (LF) and high frequency (HF) ranges. Among the study population, 129 subjects with impaired exercise capacity during the treadmill test had significantly lower HRV indices than those with preserved exercise capacity (≥90% of the age predicted maximal heart rate). After accounting for age, sex, and baseline SBP and heart rate, VLF (odds ratio per 1SD and 95% CI: 2.02, 1.19–3.42), LF (1.67, 1.10–2.55), and TP (1.82, 1.17–2.83) remained significantly associated with preserved exercise capacity. In addition, increased HRV indices were also associated with increased exercise duration, rate-pressure product, and heart rate recovery, independent of age, body mass index, and baseline SBP and heart rate. In subgroup analysis, HRV indices demonstrated similar predictive values related to exercise capacity across various subpopulations, especially in the young. In patients with CSX, HRV was independently associated with exercise capacity, especially in young subjects. The healthiness of autonomic nervous system may have a role in modulating the exercise capacity in patients with CSX.     

Power spectral analysis of heart rate variability for assessment of diurnal variation of autonomic nervous activity in guinea pigs.

We established characteristics of power spectral analysis of heart rate variability, and assessed the diurnal variations of autonomic nervous function in guinea pigs. For this purpose, an electrocardiogram (ECG) was recorded for 24 hr from conscious and unrestrained guinea pigs using a telemetry system. There were two major spectral components, at low frequency (LF) and high frequency (HF) bands, in the power spectrum of HR variability. On the basis of these data, we defined two frequency bands of interest: LF (0.07-0.7 Hz) and HF (0.7-3.0 Hz). The power of LF was higher than that of HF in the normal guinea pigs. Atropine significantly reduced power at HF. Propranolol also significantly reduced power at LF. Furthermore, the decrease in the parasympathetic mechanism produced by atropine was reflected in a slight increase in the LF/HF ratio. The LF/HF ratio appeared to follow the reductions of sympathetic activity produced by propranolol. Autonomic blockade studies indicated that the HF component reflected parasympathetic activity and the LF/HF ratio seemed to be a convenient index of autonomic balance. Nocturnal patterns, in which the values of heart rate in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed. However, the HF, LF and the LF/HF ratio showed no daily pattern. These results suggest that the autonomic nervous function in guinea pigs has no clear circadian rhythmicity. Therefore, this information may be useful for future studies concerning the autonomic nervous function in this species.     

Effects of psychological stress on autonomic control of heart in rats.

The aim of this study was to examine the effects of psychological stress on autonomic control of the heart in rats. For this purpose, we evoked anxiety-like or fear-like states in rats by means of classical conditioning and examined changes in autonomic nervous activity using an implanted telemetry system and power spectral analysis of heart rate variability. Anxiety-like states resulted in a significant increase in heart rate (HR), low frequency (LF) power, and LF/HF ratio, with no change in high frequency (HF) power. Fear-like states resulted in a significant increase in HR and a significant decrease in HF power with no significant change in both LF power and LF/HF ratio, although LF/HF ratio increased slightly. These results suggest that autonomic balance becomes predominant in sympathetic nervous activity in both anxiety-like and fear-like states. These changes in rats correspond to changes which are relevant to cardiovascular diseases in humans under many kinds of psychological stress. Therefore, the experimental design of this study is a useful experimental model for investigating the effects of psychological stress on autonomic control of the heart in humans.     

Variability of heart rhythm in dynamic study of the psychovegetative relationship in neurogenic syncope

Physiological changes accompanying syncopes of neural origin (SNO) in patients with psychovegetative syndrome are still insufficiently studied. The data concerning the role of the autonomic nervous system are discrepant. Heart rate variability was analyzed in 68 patients with SNO in a supine position and during the active 20-min orthostatic test taking into account the heart rate components of very low frequency (VLF, an index of cerebral sympathetic activity) and high frequency (HF, a marker of vagal modulation). Steady growth of the VLF and progressive decrease in the LF within 15-20 min of the orthostasis were observed in all the patients (n = 33), who fainted after this period. The predominance of the VLF in the heart rate power spectra was correlated with a high level of anxiety. It is suggested that this fact indicates the stable cerebral sympathetic activation resulting in a baroreceptor dysfunction, i.e., a failure of vasomotor regulation in patients with SNO.     

Elevated C-Reactive Protein Levels and Enhanced High Frequency Vasomotion in Patients with Ischemic Heart Disease during Brachial Flow-Mediated Dilation

Purpose

The physiological role of vasomotion, rhythmic oscillations in vascular tone or diameter, and its underlying mechanisms are unknown. We investigated the characteristics of brachial artery vasomotion in patients with ischemic heart disease (IHD).

Methods

We performed a retrospective study of 37 patients with IHD. Endothelial function was assessed using flow-mediated dilation (FMD), and power spectral analysis of brachial artery diameter oscillations during FMD was performed. Frequency-domain components were calculated by integrating the power spectrums in three frequency bands (in ms²) using the MemCalc (GMS, Tokyo, Japan): very-low frequency (VLF), 0.003–0.04 Hz; low frequency (LF), 0.04–0.15 Hz; and high frequency (HF), 0.15–0.4 Hz. Total spectral power (TP) was calculated as the sum of all frequency bands, and each spectral component was normalized against TP.

Results

Data revealed that HF/TP closely correlated with FMD (r = −0.33, p = 0.04), whereas VLF/TP and LF/TP did not. We also explored the relationship between elevated C-reactive protein (CRP) levels and vasomotion. HF/TP was significantly increased in subjects with high CRP levels (CRP;>0.08 mg/dL) compared with subjects with low CRP levels (0.052±0.026 versus 0.035±0.022, p<0.05). The HF/TP value closely correlated with CRP (r = 0.24, p = 0.04), whereas the value of FMD did not (r = 0.023, p = 0.84). In addition, elevated CRP levels significantly increased the value of HF/TP after adjustment for FMD and blood pressure (β = 0.33, p<0.05).

Conclusion

The HF component of brachial artery diameter oscillation during FMD measurement correlated well with FMD and increased in the presence of elevated CRP levels in subjects with IHD.     

迷走神经和交感神经系统不同活动状态对心率变异性的影响

实验在氯醛糖加氨基甲酸乙酯麻醉的新西兰兔上进行。记录血压、心率、心电图并对心电Ｒ－Ｒ间期（ＲＲＩ）作功率谱密度（ＰＳＤ）分析。以单调性电刺激和低频率的波动性电刺激分别刺激减压神经、疑核和右侧迷走神经外周端,观察到低频率的波动性刺激对增加ＰＳＤ中低频成分（ＬＦ）的作用比单调性电刺激更大（Ｐ〈０．０５）。注射新福林仅在头一个２５６个心动周期时间内引起总变异性（ＴＶ）、ＬＦ、ＰＳＤ中高频成分（ＨＦ）。Ｌ