Age-related changes in cardiac autonomic control during sleep

Aging is commonly associated with decreased sleep quality and increased periodic breathing (PB) that can influence heart rate variability (HRV). Cardiac autonomic control, as inferred from HRV analysis, was determined, taking into account the sleep quality and breathing patterns. Two groups of 12 young (21.1 +/- 0.8 years) and 12 older (64.9 +/- 1.9 years) volunteers underwent electroencephalographic, cardiac, and respiratory recordings during one experimental night. Time and frequency domain indices of HRV were calculated in 5-min segments, together with electroencephalographic and respiratory power spectra. In the elderly, large R-R oscillations in the very-low frequency (VLF) range emerged, that reflected the frequency of PB observed in 18% of the sleep time. PB occurred more frequently during rapid eye movement sleep (REM) sleep and caused a significant (P < 0.02) increase in the standard deviation of normal R-R intervals (SDNN) and absolute low-frequency (LF) power. With normal respiratory patterns, SDNN, absolute VLF, LF, and high frequency (HF) power fell during each sleep stage (P < 0.01) compared with young subjects, with no significant sleep-stage dependent variations. An overall decrease (P < 0.01) in normalized HF/(LF + HF) was observed in the elderly, suggesting a predominant loss of parasympathetic activity which may be related to decreased slow-wave sleep duration. These results indicate that two distinct breathing features, implying different levels of autonomic drive to the heart, influence HRV in the elderly during sleep. The breathing pattern must be considered to correctly interpret HRV in the elderly.     

The utility of low frequency heart rate variability as an index of sympathetic cardiac tone: A review with emphasis on a reanalysis of previous studies

This article evaluates the suitability of low frequency (LF) heart rate variability (HRV) as an index of sympathetic cardiac control and the LF/high frequency (HF) ratio as an index of autonomic balance. It includes a comprehensive literature review and a reanalysis of some previous studies on autonomic cardiovascular regulation. The following sources of evidence are addressed: effects of manipulations affecting sympathetic and vagal activity on HRV, predictions of group differences in cardiac autonomic regulation from HRV, relationships between HRV and other cardiac parameters, and the theoretical and mathematical bases of the concept of autonomic balance. Available data challenge the interpretation of the LF and LF/HF ratio as indices of sympathetic cardiac control and autonomic balance, respectively, and suggest that the HRV power spectrum, including its LF component, is mainly determined by the parasympathetic system.     

冠脉病变程度和心率变异相关性研究

本文采用２４小时动态心电图方法对冠心病患者和正常对照组进行心率变异时域和频域分析。结果发现单支冠脉病变组ＳＤＮＮ（Ｐ＜０．０５）、ＴＰ（Ｐ＜０．０５）和ＬＦ（Ｐ＜０．０１）低于对照组，多支冠脉病变组ＳＤＮＮｉｎｄｅｘ、ＴＰ和ＬＦ（均Ｐ＜０．０５）低于单支冠脉病变组．提示迷走神经和交感神经波动幅度下降与冠脉病变程度有关，后者是猝死的原因。     

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。     

脑卒中患者血管紧张素转换酶基因多态性与心率变异性的关联研究

目的　探讨脑卒中患者血管紧张素转换酶 (angiotensin- converting enzyme,ACE)基因多态性和心脏心率变异性的关系。方法　应用聚合酶链反应方法检测 4 3名正常人、4 6例脑梗塞患者、4 0例脑出血患者 ACE基因的插入 /缺失多态性 (insertion/deletion,I/D) ,并用心率变异性 (heart rate variability,HRV)分析方法观察其 HRV的时域、频域和混沌参数。结果　缺血性、出血性脑卒中患者的 ACE基因缺失型 (DD)及 D等位基因频率明显高于正常对照组 (P<0 .0 1) ,DD型患者的 HRV的参数值升高 ,即相邻心搏间期的均方根值、相邻心搏间期差大于 10 ms的心搏间期数占心搏间期总数的百分比、总功率谱、高功率谱、低频功率谱、混沌参数 ,明显高于 ACE基因插入型 (II)、ACE基因插入 /缺失混合型 (ID)患者 ,差异有显著性 (P<0 .0 5 )。结论　 HRV的相关参数和遗传相关 ,提示脑卒中患者有 ACE DD基因型的人 ,有脑源性心脏自主神经功能紊乱发生的危险性。     

Analysis of twenty-four hour heart rate variability in patients with panic disorder

Growing evidence suggests that alterations in autonomic function contribute to the pathophysiology of panic disorder (PD). This retrospective study employed 24-h heart rate variability (HRV) analysis of Holter records to compare autonomic function in PD patients (n = 38) with healthy, age- and gender-matched controls. Both time and frequency domain measures were calculated, and a circadian rhythm analysis was performed. The SDNN index, 5-min total power, very low frequency (VLF) and low frequency (LF) power were significantly lower in panic patients relative to controls over the 24-h period. Hourly means were significantly lower during some of the waking hours as well as the latter part of the sleep cycle. In contrast, the mean RR interval, RMSSD and high frequency (HF) power were comparable in patients and controls. Results suggest that sympathetic activity is depressed in PD patients under usual life conditions, leading to a relative predominance of vagal tone. Findings of low HRV in PD patients are consistent with the high rate of cardiovascular morbidity and mortality in this population, as well as with the emerging view of panic as a disorder involving reduced flexibility and adaptability across biological, affective and behavioral dimensions.     

不同海拔健康青年男性心率变异性对比分析

应用短程心率变异性（HRV）时域、频域和非线性分析法，对比进入三个不同海拔高度自主神经系统（ANS）调节功能的特点。发现：与进入海拔1856m相比．海拔2800m平均正常RR间期的标准差（SDNN）、相邻RR间期差的均方根（rMSSD）、相差〉50ms的相邻RR间期占RR间期总数的百分比（PNNS0）、低频成分（LF）、高频成分（HF）以及总功率（TP）均有轻度升高，但无统计学差异；与进入海拔1856m和海拔2800m相比．海拔3040mSDNN、rMSSD、LF和HF显著降低。这表明进入海拔3040m副交感神经活动显著减弱、自主神经系统调节功能显著受抑。自主神经的这种变化有助于进一步阐明进入高海拔机体发生的病理生理学改变。     

Effect of upper airway surgery on heart rate variability in patients with obstructive sleep apnoea syndrome

To determine whether surgery influences cardiovascular autonomic modulation in obstructive sleep apnoea syndrome (OSAS), the present study was performed to evaluate the effect of upper airway (UA) surgery on heart rate variability (HRV) using frequency domain analysis for patient groups who have had either successful or unsuccessful surgery. We compared body mass index (BMI), polysomnographic [apnoea index (AI), apnoea-hypopnoea index (AHI), minimum SaO(2)] and HRV [very low frequency (VLF) power, low frequency (LF) power, high frequency (HF) power, HF/LF ratio, LFnu = LF/(LF + HF), HFnu = HF/(LF + HF)] parameters between the unsuccessful (n = 14) and successful (n = 22) surgical groups before and after UA surgery. Significant changes were observed for the successful patient group with respect to mean AI (from 29.1 ± 21.3 to 2.0 ± 3.2 events h(-1), P < 0.001), AHI (from 38.6 ± 20.0 to 5.6 ± 5.1 events h(-1), P < 0.001), minimum SaO(2) (from 73.3 ± 12.7 to 86.3 ± 6.5%, P < 0.001), VLF power (from 25599 ± 12906 to 20014 ± 9839 ms(2), P = 0.013), LF power (from 17293 ± 7278 to 14155 ± 4980 ms(2), P = 0.016), LFnu (from 0.700 ± 0.104 to 0.646 ± 0.128, P = 0.031) and HFnu (from 0.300 ± 0.104 to 0.354 ± 0.128, P = 0.031); however, mean BMI, HF power and LF/HF ratio did not change significantly after UA surgery. No significant changes were observed in the unsuccessful surgical group. Successful UA surgery may improve cardiac sympathetic and parasympathetic modulation in patients with OSAS.     

Correlation between the severity of obstructive sleep apnea and heart rate variability indices

The risk of cardiovascular disease is known to be increased in obstructive sleep apnea syndrome (OSAS). Its mechanism can be explained by the observation that the sympathetic tone increases due to repetitive apneas accompanied by hypoxias and arousals during sleep. Heart rate variability (HRV) representing cardiac autonomic function is mediated by respiratory sinus arrhythmia, baroreflex-related fluctuation, and thermoregulation-related fluctuation. We evaluated the heart rate variability of OSAS patients during night to assess their relationship with the severity of the symptoms. We studied overnight polysomnographies of 59 male untreated OSAS patients with moderate to severe symptoms (mean age 45.4+/- 11.7 yr, apnea-hypopnea index [AHI]=43.2+/-23.4 events per hour, and AHI >15). Moderate (mean age 47.1+/-9.4 yr, AHI=15-30, n=22) and severe (mean age 44.5 +/-12.9 yr, AHI >30, n=37) OSAS patients were compared for the indices derived from time and frequency domain analysis of HRV, AHI, oxygen desaturation event index (ODI), arousal index (ArI), and sleep parameters. As a result, the severe OSAS group showed higher mean powers of total frequency (TF) (p=0.012), very low frequency (VLF) (p= 0.038), and low frequency (LF) (p=0.002) than the moderate OSAS group. The LF/HF ratio (p=0.005) was higher in the severe group compared to that of the moderate group. On the time domain analysis, the HRV triangular index (p=0.026) of severe OSAS group was significantly higher. AHI was correlated best with the LF/HF ratio (r(p))=0.610, p<0.001) of all the HRV indices. According to the results, the frequency domain indices tended to reveal the difference between the groups better than time domain indices. Especially the LF/HF ratio was thought to be the most useful parameter to estimate the degree of AHI in OSAS patients.     

Platelet Serotonin Transporter Function and Heart Rate Variability in Patients with Panic Disorder

Many studies showed abnormal serotonin transporter (5-HTT) function and heart rate variability (HRV) in panic disorder patients. The present study investigated the relationship between HRV power spectral analysis findings and platelet serotonin uptake in panic disorder patients. Short-term HRV over 5 min and platelet serotonin transporter uptake parameters (V_max and K_m) were measured both in 45 patients with panic disorder and in 30 age-matched normal healthy control subjects. Low frequency power (LF) normalized unit (nu) and LF/high frequency power (HF) were significantly higher, whereas HF and HF nu were lower in the patient group than in the control group. V_max and K_m were all significantly lower (i.e., reflects decreased 5-HTT function) in patients with panic disorder than in normal controls. In the patient group, K_m was negatively correlated with LF/HF and LF nu whereas no such correlations between them were found in the control group. By multivariate analysis based on multiple hierarchical linear regression, a low K_m independently predicted an increased LF nu even after controlling for age, sex, and body mass index in the patient group. These results suggest that impaired 5-HTT function is closely related to dysregulation of autonomic nervous system in panic disorder.     

Impact of chronic obstructive pulmonary disease on linear and nonlinear dynamics of heart rate variability in patients with heart failure

The objective of this study was to investigate the impact of chronic obstructive pulmonary disease (COPD)-heart failure (HF) coexistence on linear and nonlinear dynamics of heart rate variability (HRV). Forty-one patients (14 with COPD-HF and 27 HF) were enrolled and underwent pulmonary function and echocardiography evaluation to confirm the clinical diagnosis. Heart rate (HR) and R-R intervals (iRR) were collected during active postural maneuver (APM) [supine (10 min) to orthostasis (10 min)], respiratory sinus arrhythmia maneuver (RSA-M) (4 min), and analysis of frequency domain, time domain, and nonlinear HRV. We found expected autonomic response during orthostatic changes with reduction of mean iRR, root mean square of successive differences between heart beats (RMSSD), RR tri index, and high-frequency [HF (nu)] and an increased mean HR, low-frequency [LF (nu)], and LF/HF (nu) compared with supine only in HF patients (P<0.05). Patients with COPD-HF coexistence did not respond to postural change. In addition, in the orthostatic position, higher HF nu and lower LF nu and LF/HF (nu) were observed in COPD-HF compared with HF patients. HF patients showed an opposite response during RSA-M, with increased sympathetic modulation (LF nu) and reduced parasympathetic modulation (HF nu) (P<0.05) compared with COPD-HF patients. COPD-HF directly influenced cardiac autonomic modulation during active postural change and controlled breathing, demonstrating an autonomic imbalance during sympathetic and parasympathetic maneuvers compared with isolated HF.     

Heart rate variability and endogenous sex hormones during the menstrual cycle in young women

To our knowledge, the relationship between all four endogenous female sex hormones and resting cardiac autonomic function has not been studied. The aim of the current study was to examine the association between the normal endogenous levels of oestrogen (17beta-oestradiol), progesterone, luteinising hormone and follicle-stimulating hormone and heart rate variability (HRV) during the menstrual cycle in young eumenorrheic women. Ten healthy, young, female subjects volunteered for this study. HRV and endogenous hormone levels were recorded at three phases of the menstrual cycle: menses (day 3.8 +/- 0.5), ovulation (day 15.8 +/- 0.7) and luteal (day 22.1 +/- 0.4) to ensure HRV recordings at times of low (menses) and high (ovulation and luteal) hormonal influence. Heart rate recordings were obtained from supine resting subjects and analysed on a Holter analysis system. Total power (TP, 0-1.0 Hz), low frequency (LF, 0.041-0.15 Hz), high frequency (HF, 0.15-0.80 Hz) and LF/HF components of HRV were examined. Despite a significantly greater HR at ovulation and normal cyclic variations in all endogenous sex hormone levels, no measure of HRV was significantly different between menstrual cycle phases. Significant correlations between oestrogen levels and absolute measures of HRV at ovulation were identified. The results of the current study demonstrated that the normal cyclic variations in endogenous sex hormone levels during the menstrual cycle were not significantly associated with changes in cardiac autonomic control as measured by HRV. Significant correlation between peak oestrogen levels and HRV measures at ovulation provided further support for the reported cardioprotective effects of oestrogen in healthy females.     

Relationship between electroencephalogram slow-wave magnitude and heart rate variability during sleep in humans

To explore whether depth of sleep is related to changes in autonomic control, continuous power-spectral analysis of the electroencephalogram (EEG) and heart rate variability (HRV) was performed in ten normal subjects during nocturnal sleep. Quiet sleep (QS) was associated with an increase in high-frequency power (HF) of HRV (0.15-0.4 Hz) but a decrease in low-frequency power (LF) (0.04-0.15 Hz) to HF ratio (LF/HF) compared with awakening. During QS, LF/HF was significantly and negatively correlated with delta power of EEG (0.5-4.0 Hz), whereas mean R-R interval and HF were not. We conclude that during QS, cardiac sympathetic regulation is negatively related to the depth of sleep, although vagal regulation is not. Our methodology offers a quantitative analysis to study the interaction between cerebral cortical and autonomic functions.     

亚健康人群心率变异性特点的研究

目的 探讨亚健康状态人群自主神经功能的特点.方法 随机选取70例亚健康状态人员,75例健康状态人员分别接受短时(5分钟)心率变异性分析,以正常心动周期的标准差(SDNN)、总功率(TP)、低频功率(LF)、高频功率(HF)、低频功率与高频功率比值(LF/HF)为考察指标,记录并进行统计学分析.结果 亚健康状态人群正常心动周期的标准差和总功率都显著低于健康人群(t=-4.643,P=0.00;t=-3.492,P=0.002);同时与健康人群比较,亚健康状态人群的低频功率增高,但未达统计学意义(t=0.898,P=0.377);高频功率有所下降,亦未达到统计学水平(t=-0.899,P=0.376);亚健康状态人群的低频功率与高频功率比值(LF/HF)与健康人群没有差异(t=0.943,P=0.354).结论 亚健康状态人群心率变异性降低,自主神经系统功能减退.     

火炮参试人员应激反应对心血管和植物神经功能的影响

目的：探讨火炮参试人员心理应激时心脏植物神经，心电图和血压的变化规律。方法：对40名健康者在试验前进行SCL－90测评，试验期间进行动态心电图和血压观察，用时域和频域法分析。并与平时平静状态同一时程对照。结果：试验时与平时比较，SCL－90因子分中有5个因子分明显增高，时域中Mean RR,SDNN rMSSD降低，频域中VLF，LF，LF／HF，VLF／HF增高，早搏增多，血压增高，心率增快，且差异有显著性，结论：心理应激反应影响心脏植物神经经和心血管功能。     

抑郁对急性心肌梗死患者心率变异及预后的影响

研究发现 ,冠心病患者常合并焦虑、抑郁情绪障碍 ,抑郁被认为是冠心病的独立危险因素[1,2 ] 。心率变异性 (ｈｅａｒｔｒａｔｅｖａｒｉａｂｉｌｉｔｙ ,ＨＲＶ)是指窦性心率在一定时间内周期性改变的现象 ,是反映交感与副交感神经张力及其平衡的重要指标。ＨＲＶ减低是确定急性心肌梗死 (ａｃｕｔｅｍｙｏｃａｒｄｉａｌｉｎｆａｒｃｔｉｏｎ ,ＡＭＩ)患者危险分层 ,预测其预后的一个独立的敏感指标[3] 。因此 ,本研究旨在观察抑郁对ＡＭＩ患者ＨＲＶ及近期预后的影响。1　对象与方法1.1　对象选择 1999年 5月～ 2 0 0 1年 12月住院、未行…     

小儿心肌炎的心率变异性

目的:探讨小儿心肌炎的心率变异性。方法:采用ECG-LA2.OGold型心电综合分析系统,描记肢体导联采样5分钟,应用时域及功率谱分析法,通过计算机计算出全部R-R间期的标准差(sDNN),极低频(VLF)低频(LF)高频(HF)。结果:以SDNN<27ms为阳性诊断标准,将57例小儿心肌炎病儿分为两组,一组SDNN<27ms共17例,病情较重,另一组SDNN>27ms共41例,病情较轻。结论:病情较重的心肌炎患儿短程HRV降低SDNN<27ms。     

Reproducibility of resting heart rate variability with short sampling periods.

The purpose of this study was to determine whether resting heart rate variability (HRV) is reproducible with short sampling measurement periods using an office-based personal computer measurement system. Eight healthy active women participated in ECG analyses on 2 days within 1 week under controlled environmental and physiological conditions. After they rested for 10 minutes, a 10-min ECG was recorded. HRV was determined from a 2.5- and 5-min sample period using both time domain variables (meanRR and SDNN) and frequency domain variables (LF, HF, LF:HF). Repeated measures ANOVA found no significant differences between Day 1 and Day 2 for either sampling period (p > or = 0.23). For both the 2.5- and 5-min sampling periods, the intraclass correlations between days for the time domain variables showed good reproducibility (R = 0.86-0.90). The reproducibility of the frequency domain variable was only average (R = 0.67-0.96), with the LF:HF ratio yielding the higher R values.     

Heart rate variability is related to self-reported physical activity in a healthy adolescent population

This study investigated whether there is a relationship between heart rate variability (HRV) versus lifestyle and risk factors for cardiovascular disease in a population of healthy adolescents. HRV is as an index of tonic autonomic activity and in adults HRV is related to lifestyle and risk factors for cardiovascular disease, but it is not known if this is the case in adolescents. HRV was registered for 4 min in sitting position in 99 healthy adolescents (age range 15 years 11 months–17 years 7 months) and repeated after 6 months. On both occasions there were significant correlations (P < 0.05) between physical activity and HRV, with respective r values: high frequency (HF) 0.26, 0.30; low frequency power (LF) 0.35, 0.29 and the standard deviation of inter-beat intervals (SDNN) 0.28, 0.37. There was no significant interaction between first and second measurements. In contrast, there were no correlations to sleeping patterns, eating habits and smoking. Risk factors for cardiovascular disease [body mass index (BMI = weight (kg)/length in m²), systolic blood pressure and p-glucose] did not show any repeatable significant correlations to HRV. Multiple regression models showed that physical activity was a predictor for HF, LF and SDNN in both measurements. In conclusion HF, LF and SDNN were reproducible after 6 months and were related to physical activity on both occasions.     

The effect of ventilation on spectral analysis of heart rate and blood pressure variability during exercise

Heart rate variability (HRV) and systolic blood pressure variability (BPV) during incremental exercise at 50, 75, and 100% of previously determined ventilatory threshold (VT) were compared to that of resting controlled breathing (CB) in 12 healthy subjects. CB was matched with exercise-associated respiratory rate, tidal volume, and end-tidal CO(2) for all stages of exercise. Power in the low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, >0.15-0.4 Hz) for HRV and BPV were calculated, using time-frequency domain analysis, from beat-to-beat ECG and non-invasive radial artery blood pressure, respectively. During CB absolute and normalized power in the LF and HF of HRV and BPV were not significantly changed from baseline to maximal breathing. Conversely, during exercise HRV, LF and HF power significantly decreased from baseline to 100% VT while BPV, LF and HF power significantly increased for the same period. These findings suggest that the increases in ventilation associated with incremental exercise do not significantly affect spectral analysis of cardiovascular autonomic modulation in healthy subjects.