隐性心肌缺血发作前心率变异性

隐性心肌缺血发作前心率变异性心率变异性（ｈｅａｒｔｒａｔｅｖａｒｉａｂｉｌｉｔｙ，ＨＲＶ）的功率谱分析结果已被视为自主神经活性的一项非侵入性参数。其低频（ＬＦ）成分反映在副交感神经调节下的交感活性，高频（ＨＦ）成分反映纯粹的副交感活性；ＬＦ／ＨＦ比值...     

Poincare散点图在分析慢性充血性心力衰竭心率变异中的应用

目的：探讨Ｐｏｉｎｃａｒｅ散点图在分析慢性充生心力衰竭（ＣＨＦ）患者心率变异（ＨＢＶ）中的使用价值;方法：分析３０例ＣＨＦ患者和３０例正常人ＨＲＶ的Ｐｏｉｎｃａｒｅ散点图及其定量指标,矢量长度指数（ＶＬＩ）和矢量角度指数（ＶＡＩ）,并与部分时域指标（ＳＤＮＮ〉ＳＤＳＤ）进行相关分析。结果：正常人散点图无呈慧星型,ＣＨＦ患者呈鱼雷型及短棒型,ＣＨＦ患者２４小时、清醒、睡眠时的ＶＬＩ、ＶＡ与正常组比较     

高血压病合并左心室肥厚及冠心病患者心率变异性分析

目的：观察高血压伴呈不伴左心室肥厚（ＬＶＨ）及冠心病（ＣＨＤ）患者的心率变异性（ＨＲＶ）的变化，以了解三者之间的关系。方法：对Ⅰ期高血压病患者４０例（Ａ组），伴ＬＶＨ的高血压病患者３７例（Ｂ组）及高心病合并ＣＨＤ患者３９例（Ｃ组），进行动态心电图检查，分析２４ｈＨＲＶ时域及频域指标。结果：Ｂ组、Ｃ组与Ａ组比较，ＳＤＮＮ，ＳＤＡＮＮ Ｉｎｄｅｘ，ＳＤＮＮ Ｉｎｄｅｘ，ＰＮＮ５０均降低（Ｐ〈０．９５，     

心率变异、心室晚电位和Q-T离散度预测急性心肌梗死预后的探讨

目的 了解心率变异（ＨＲＶ）、Ｑ－Ｔ离散度（Ｑ－Ｔｄ）和心室晚电位（ＶＬＰ）在预测急性心肌梗死９ＡＭＩ）预后的价值。方法 ４０例ＡＭＩ患者ＨＲＶ（ＳＤＮＮ）、Ｑ－Ｔ、ＶＬＰ测定,与４０例正常人进行对比分析。结果人ＡＭＩ组ＳＤＮＮ与对照组比较明显减低（Ｐ〈０．００１）,Ｑ－Ｔｄ明显延长（Ｐ〈０．００１）,ＶＬＰ阳性率明显增高（Ｐ〈０．０１）。梗死患者室性心律失常事件组与非事件组ＨＲＶ（ＳＤＮＮ）、Ｑ     

高血压性左心室肥厚与心率变异相关性及预后分析

目的：探讨原发性高血压左心室肥厚（ＬＶＨ）心率变异的相关性及预后。方法：采用彩色多普勒超声诊断仪，结合心率变异性（ＨＲＶ），对高血压有或无左心室肥厚患者进行相关性分析，并用心率变异性指数（ＨＲＶＩ）对高血压病患者进行预后分析。结果：伴有ＬＶＨ的高血压患者和无ＬＶＨ的高血压患者ＨＲＶＩ均低于对照组，其不良事件的发生率高于对照组，伴ＬＶＨ组更明显。结论：提示高血压ＬＶＨ患者交感神经功能亢进，迷走神经张     

Holer监测中心肌缺血发生的昼夜规律及其与缺血阈值及自主神经活性的关系

本文监测了５０例冠心病病人的动态心电图，分析心肌缺血发生的昼夜变化及与缺血阀值及自主神经调节的关系，用心率变异（ＨＲＶ）能谱评价自主神经活性的变化。结果：心肌缺血最多发生在上午６～１１点，此时的缺血阀值较高，交感神经兴奋性增强，第二峰出现在晚７～１０点。ＨＲＶ分析结果显示白天以交感神经兴奋占优势，夜间以迷走神经兴奋为主，清晨由迷走神经兴奋急转为交感神经兴奋。心梗病人的高频成分（ＨＦ：代表迷走神经活性）较稳定性心绞痛病人显著降低（５４．２±２５．１～１０１．５±８４．５ｍｓ２，ｐ＜０．０５），心肌缺血阀值较高的低频成份（ＬＦ：反映交感神经张力）发作时较发作前增高（１６３．４±８４．５～２４７．２±６２．１ｍｓ２，ｐ＞０．０１），ＨＲＶ中ＬＦ与心肌缺血发生次数呈正相关（ｒ＝０．６７）。结论：心肌缺血的发生与缺血阀值及自主神经活性关系密切，清晨自主神经调节的突然变化可发挥板机效应促发一系列心脏急症在此刻的高发。     

参麦注射液对慢性充血性心力衰竭患者心率变异性的影响

目的：探讨参麦注射液对慢性充血性心力衰竭（ＣＨＦ）患者心率变异性（ＨＲＶ）的影响。方法：将４２４例ＣＨＦ患者随机分为２组：参麦注射液加常规抗心力衰竭（心衰）治疗组（参麦组）３１６例,常规抗心衰治疗对照组１０８例。治疗前进行ＨＲＶ测定,２组间比较各指标均无显著性差异（Ｐ均〉０．０５）,治疗１个疗程（１５日）后再次进行ＨＲＶ测定。结果：①参麦组治疗后２４小时５分钟平均正常Ｒ－Ｒ间期标准差（ＳＤＡＮＮ）     

美托洛尔对慢性心衰伴室性心律失常疗效初探

慢性心衰（ＣＨＦ）合并室性心律失常（ＶＡ）同时伴心率变异（ＨＲＶ）下降（ＳＤＮＮ＜７０ｍｓ）８４例，给予小剂量美托洛尔治疗，剂量为１２．５～５０ｍｇ／ｄ，观察治疗前后动态心电图（ＤＣＧ）及ＨＲＶ改变。治疗前ＤＣＧ发现简单型ＶＡ３１例，复杂型ＶＡ３６例，短阵室速２６例，ＨＲＶ下降程度与ＶＡ严重程度相一致。治疗后冠心、高心、扩心、风心病组有效率分别为８７．８％，７６．９％，８４．６％，６６．７％。说明适当剂量美托洛尔可作为治疗ＣＨＦ伴ＶＡ基础药物之一。     

正常人心率变异频谱分析

心率变异频谱分析（ＨＲ－ＳＰＡ）是新近开发的可同时对支配心脏交感、迷走神经活动水平及其平衡提供准确定量的一项有用指标。具有无创、重复性好和短时间段分析与长程分析的结果十分接近等优点，显示其在临床应用的广阔前景。对３３列正常人选择日、夜间两个时间段进行ＨＲ－ＰＳＡ。结果显示日间低频（ＬＦ）和高频（ＨＦ）成分分别为（５８６．７±１３２．１）ｍｓ＾２／Ｈｚ和（３４３．２±１２１．９）ｍｓ＾２／Ｈｚ。说明     

糖尿病合并心血管疾病患者昼夜心率变异性分析

目的：研究糖尿病合并心血管疾病对心率变异性（ＨＲＶ）的影响。方法：对２２例合并高血压、冠心病及２４例单纯糖尿病患者进行２４小时心率变异性时域分析，并进一步发现其昼夜变化规律，同时与年龄、性别相当的３１例正常人ＨＲＶ资料比较。结果：１糖尿病患者各项时域分析指标均较正常组降低（Ｐ〈０．０５）；２与单纯糖尿病患者比较，有心血管合并症的糖尿病患者ＨＲＶ参数中ＳＤＮＮ、ＳＤＡＮＮ、ＳＤＮＮ－ｉｎｄｅｘ、ＲＭ     

急性冠脉综合征心率震荡昼夜节律及其与心率变异的相关性分析

目的 研究急性冠脉综合征患者心率震荡(heart rate turbulence,HRT)的昼夜节律性,并通过HRT指标与心率变异性指标的相关性分析,进一步探讨HRT与自主神经的关系.方法 连续入选急性冠脉综合征患者91例,分析一天中的两个时段即白天(7: 00～19: 00)和夜间(0: 00～6: 00)HRT的变化.从上午7: 00和凌晨0: 00开始各按顺序入选3个室早,根据文献计算HRT指标[震荡初始(TO)、震荡斜率(TS)]的数值.心率变异性选用的时域指标有SDNN、RMSSD,频域指标包括LF、HF、LF/HF.结果 ①TO值白天较夜间高,TS值白天较夜间低,均存在明显的昼夜节律.②TS与SDNN之间存在正相关关系(r=0.44),TS与LF/HF之间亦存在正相关关系(r=0.51).结论 急性冠脉综合征HRT存在昼夜节律变化且与HRV密切相关,提示HRT不仅反映心血管系统自主神经的反射性调节,在某种程度上也反映交感-迷走神经的紧张性调节.     

Sensitivity of HRV parameters including pNNxx proven by short-term exposure to 2700 m altitude

Analysis of heart rate variability (HRV) is increasingly applied in research and intervention. However, the sensitivity of the variety of HRV parameters for changes in cardiovascular reactivity remains unclear. This study investigated effect sizes of HRV parameters in an experimental field study, exposing persons to 2700 m altitude. Parameters analyzed were mean heart rate (HR), atrioventricular conduction time, SDNNi, rMSSD, pNN50, pNNxx (xx = pNN05, pNN10, pNN20, pNN25, pNN30, pNN40), LF, HF, LFnu, LF/HF ratio, and Total Power, as well as ratings of arousal and mood. Forty-five persons were taken to the Dachstein mountain by cable car. HRV parameters of 40 min epochs and ratings at 170 m and 2700 m were compared. At altitude, HR increased and HRV decreased in all parameters. Although moods were not changed, test persons experienced higher arousal at altitude. Besides for HR, analysis revealed the highest effect size for SDNNi, followed by pNN20 and pNN25 and was much lower for HF. As pNNxx parameters were highly correlated with HF, they are discussed to reflect vagal activity. Moreover, pNNxx parameters are clearly defined, whereas HF is susceptible to variations in computation; thus pNNxx parameters seem preferable due to higher effect sizes and better comparability.     

慢性肺心病患者的心率变异性

目的：观察慢性肺心病患者心率变异性，了解其自主神经功能的变化。方法：对25例慢性肺心病，25例健康对照者（对照组）作前瞻性对照研究，记录24h动态心电图，作时域和频域分析，结果：与对照组比较，肺心病组相邻心搏的R－R间期之差＞50ms的心搏数占R－R间期数的百分(pNN50)，每5min正常R－R间期标准差的平均值（SDANN），频域指标的高频（HF）明显降低，低频与高频的比值（LF／HF），明显升高，差异均有非常显著意义（P均＜0．01），而频域指标的低频（LF）无明显变化（P＞0．05），经过治疗后，肺心病组处于缓解期，与治疗前比较，HF，PNN50，SDANN等指标明显增加，而LF／HF明显降低，差异均有非常显著意义（P均＜0．01），肺心病组病人治疗后HF，pNN50,SDANN等指标均低于对照组，而LF／HF明显高于对照组，差异均有非常显著意义（P均＜0．01），肺心病组治疗后LF与治疗前及对照组比较，差异不具显著意义（P＞0．05）。结论：肺心中层得不仅交感神经活动占优势，同时并存迷走神经功能受损，自主神经功能可能存在连续性障碍。     

Cardiac sympathovagal balance during sleep apnea episodes

Summary. The main acute cardiovascular effects of obstructive sleep apnea syndrome (OSAS) are elevation of blood pressure and reflectory bradycardia, which are followed by an abrupt tachycardia on resumption of breathing. This haemodynamic instability is related to hypoxemia and arousal, and may lead to increased risk from cardiac arrhythmias and sudden cardiac death, as well as to the development of chronic arterial hypertension, in these patients. The aim of this study was to apply frequency domain analysis of heart rate variability (HRV) measured from continuous electrocardiogram (ECG) recordings to evaluate how cardiac autonomic function, and especially cardiac sympathovagal tone, changes during sleep apnea episodes. We identified 41 apneas leading to more than 4%-unit arterial oxygen desaturation in 12 patients (11 men, 1 women, age range 27–67 years). Frequency domain analysis of HRV was performed from ECG recordings using 4 min epochs starting 20 min before apnea began and lasting 20 min after the beginning of apnea. The mean (± SEM) fall in oxygen saturation during the apnea was 6.8±0.6%-units. While high frequency band (HF, reflects cardiac vagal activity) remained unchanged, low frequency band (LF, mainly sympathetic activity) showed a constant increase, leading to significant change in the sympathovagal balance (LF/HF ratio). In conclusion, concordantly with previous peripheral sympathetic-nerve recordings, frequency domain analysis of HRV is able to detect sympathetic activation during sleep apnea episodes, leading to marked change in the sympathovagal balance.     

Difference in Autonomic Nervous Control between Ventricular Septal Defect and Atrial Septal Defect Based on Heart Rate Variability

Background: We hypothesized that patients with atrial (ASD) and ventricular septal defects (VSD) have similarly reduced heart rate variability (HRV) since both defects cause similar increases in pulmonary blood flow and right ventricular filling pressure. We examined the correlation between HRV and respiratory frequency (RSA) characteristics and left-to-right shunt ratio (Qp/Qs) measured by Doppler echocardiography.
Methods: The study included 83 patients with diagnoses of ASD (n = 43) or VSD (n = 40). The electrocardiogram and respiratory waves were recorded during Doppler echocardiography test, and HRV was measured to calculate the low frequency (LF), high frequency (HF), total frequency (TF), and RSA components, and the LF/HF, RSA/TF, and LF/RSA ratios. Qp/Qs was calculated from Doppler echocardiography and its relationship with HRV parameters was examined by multivariate analysis.
Results: There was a positive correlation between Qp/Qs and LF/RSA in the ASD group, and a negative correlation in the VSD group. In contrast, Qp/Qs correlated negatively with RSA/TF in the ASD group, and positively in the VSD group.
Conclusion: Different effects of respiratory vagal activity on HRV were observed in patients with ASD versus VSD.     

Heart Rate Variability: Its Association with Hemodynamic Function of the Left Ventricle in Patients with Coronary Heart Disease

Patients with heart failure secondary to coronary heart disease (CHD) are characterized by an imbalance of the autonomic nervous system, which can be assessed by analysis of the heart rate variability (HRV). However it is still unclear whether all patients with CHD reveal suppression of HRV and if it is related to hemodynamic function and contractile disturbances of the left ventricle. To answer these questions data from 105 consecutive patients were analyzed and compared with 17 healthy subjects. All study participants underwent 24-hour ambulatory ECG recordings with calculation of HRV parameters and angiographic examination after collection of clinical data and other noninvasive evaluations. Time- (SDRR, SDANN, SD, pNN50) and frequency- (LF, HF) domain parameters of HRV were assessed. All ventriculographic and hemodynamic measurements were used in the analysis. Highly significant correlations were found between all HRV parameters, and left ventricular ejection fraction (LVEF) and left ventricular end-diastolic pressure (P < 0.001). Patients with LVEF < 40% were characterized by significantly lower values of HRV and impairment or lack (LVEF < 20%) of diurnal variation of frequency-domain measurements of HRV. Patients with segmental akinesis or dyskinesis also had lower values of HRV. The group with dyskinesis was characterized by significantly lower diurnal rhythms of LF and HF, independent of LVEF.     

Heart rate variability and autonomic nervous system changes in children with vasovagal syncope

The aim of this study was to evaluate the HRV at rest and during tilt test (HUTT) in children with a history of vasovagal syncope and to link the HRV indices with the clinical results of the test. HRV indices were assessed in the supine position and during the initial 5 minutes of the 60-degree HUTT in 49 patients (33 females, 16 males, mean age of 13 +/- 2.8 years) who were evaluated for recurrent syncope. The positive to negative results of the test were 21 to 28. The normalized power of high frequency component (npHF) decreased, normalized power of low frequency component (npLF) and the LF:HF ratio increased during HUTT of tilt-positive patients (P < 0.05 for each parameter). Parallel changes, but to a lesser degree, were observed for similar HRV parameters of tilt-negative patients. In addition, the HF and all the time-domain indices decreased significantly (P < or = 0.05) during HUTT in the latter group. When the tilt-positive and -negative patients were compared, the npHF was lower (P = 0.002), npLF and LF:HF ratio were higher (P = 0.01 and P = 0.001, respectively) during the test in tilt-positive patients, reflecting increased sympathetic tone in this group. A cut-off point for LF:HF was assigned as 2.7 for differentiating tilt-negative and tilt-positive results. The specificity, sensitivity, and positive and negative predictive values of this cut-off point were calculated as 93%, 52%, 85%, and 41%, respectively. Patients with vasovagal syncope show variations in vagal autonomic tone and appear to be more prone to syncope when their sympathetic tone is elevated at the beginning of the test. LF:HF > 2.7 is a specific marker (specificity 93%) and can correctly predict a positive tilt test in 85% of patients.     

Sympathovagal Balance Prior to Onset of Repetitive Monomorphic Idiopathic Ventricular Tachycardia

Repetitive monomorphic idiopathic (RMI) ventricular tachycardia (VT) occurs typically in patients without structural heart disease, originates in most cases from the right ventricular outflow tract, and can often be induced by exercise or isoproterenol. This study analyzed the dynamic changes in autonomic tone immediately before the spontaneous onset of RMIVT using frequency-domain heart rate variability (HRV) indices. We analyzed the ambulatory electrocardiographic recordings from 6 men and 8 women (mean age: 43 ± 18 years; mean number of VT runs per day: 134 ± 213; mean VT rate: 194 ± 40 bpm; median VT run length: 4 cycles) with RMIVT. A total of 36 clusters of nonsustained episodes of RMIVT preceded by ≥1 hour of sinus rhythm without VT were analyzed (25 minutes before the onset of RMIVT divided into five 5-minute periods; 8 minutes before onset of RIMVT divided into eight 1-minute periods). During 25 minutes preceding the onset of VT, the mean RR interval decreased from 767 ± 118 to 723 ± 105 ms (P = 0.015) and the low-frequency (LF)/high-frequency (HF) ratio increased from 2.24 ± 0.79 to 2.49 ± 1.0 (P = 0.03). During the 8 minutes before VT onset, the mean RR interval decreased from 745 ± 118 to 718 ± 102 ms (P = 0.001) and the LF components increased from 205 ± 72 to 253 ± 113 ms (P = 0.014). No change in HF components was observed during the 25 or 8 minutes periods preceding the RMIVT onset. The changes in HRV indices suggest a strong time-dependent primary activation of sympathetic tone prior to the occurrence of RMIVT. Withdrawal of vagal tone does not appear essential to the initiation of RMIVT clusters.     

Analysis of Heart Rate Variability Five Minutes Before the Onset of Paroxysmal Atrial Fibrillation

BACKGROUND: Various experimental and clinical observations suggest changes in sympathetic and vagal neural regulatory mechanisms play a critical role in altering cardiac electrical properties and favor the occurrence of arrhythmic events. There is limited information about the influences of the autonomic tone on the development of episodes of paroxysmal atrial fibrillation in patients with no evidence of organic heart disease. The aim of this study was to investigate changes in sympatho-vagal balance 5 minutes before the onset of atrial fibrillation. METHODS: We evaluated 28 patients with no history of heart disease who were not undergoing pharmacological treatment and who had at least one episode of paroxysmal atrial fibrillation recorded during an 24-hour ECG Holter monitoring. We analyzed values of frequency domain heart rate variability parameters 5 minutes before the onset of atrial fibrillation (prefa period) compared to an equivalent period at least 1 hour after from atrial fibrillation (random period). RESULTS: Thirty-six episodes of atrial fibrillation were recorded and our results showed we had two types of episodes. Eighteen were classified as Type A, in which we had an increase of low frequency (LF) (79.15 +/- 10.76 in comparison with 62.64 +/- 19.55) (P = 0.004) and a decrease of high frequency (HF) (20.82 +/- 10.74 in comparison with 37.64 +/- 20.20) (P = 0.004) consistent with an increase of sympathetic tone; and 18 were classified as Type B in which there was a decrease of LF (62.82 +/- 15.38 in comparison with 85.97 +/- 8.48) (P < 0.001), and an increase of HF (36.79 +/- 14.72 compared with 14.01 +/- 8.48) (P < 0.001), consistent with an increase of parasympathetic tone. CONCLUSION: We observed abrupt changes in sympathovagal balance in the last 5 minutes preceding an episode of atrial fibrillation. This can be related to a double behavior in the neurogenic drive: in Type A episodes there is an increase of the LF spectrum, LF:HF ratio, and a decrease of the HF spectrum consistent with an increase of neurogenic sympathetic drive; in Type B episodes there is a reduction of the LF spectrum, LF/HF ratio, and an increase of HF spectrum consistent with an enhancement of the neurogenic parasympathetic drive. In some patients, we found that the two mechanisms operate during different hours of the day and that sometimes there is an increase of sympathetic tone, and in the same instances an increase of parasympathetic tone. Heart-rate variability measures fluctuation in autonomic inputs to the heart rather than the mean level of autonomic impulse; autonomic imbalance is probably more important than the vagal or sympathetic drive alone.     

Influence of age and gender on autonomic regulation of heart

Heart rate variability (HRV) is a non-invasive method to measure cardiac autonomic function. Impairments in HRV have been proposed as independent risk factor for increased cardiac mortality and morbidity. Cardio protective phenomenon in females has been hypothesized to be due to differential autonomic tone. Age related loss of vagal control has been reported as predisposing factor for the development of cardiovascular disease. In this study we assessed effect of age and gender on autonomic regulation of heart in healthy volunteers. HRV data of 189 subjects (114 males and 75 females) were analyzed in time and frequency domains using customized program. Artifact free 5 min electrocardiogram segment was used for analysis. It was ensured that none of the subject had medical illness such as diabetes, hypertension, thyroid disorders, cardiac disorders, diseases potentially related with autonomic neuropathy and major psychiatric illness by careful history and clinical examination. HRV recordings were done under standard laboratory condition. On correlation analysis SDNN, RMSSD, total power negatively correlated with age suggesting reduced autonomic regulation of heart with increase in age (SDNN: r = ?0.444, p < 0.01; RMSSD: r = ?0.552, p < 0.01; total power: r = ?0.474, p < 0.01); similarly High frequency power (HF.nu) negatively correlated with age (r = ?0.167, p = 0.02), denoting loss of vagal tone with aging. LF/HF ratio correlated positively with age (r = 0.19, p < 0.01) suggesting a relative increase of sympathetic activity with increase in age. On multiple regression analysis to control for effect of age and heart rate while comparing males and females, LF.nu showed significant reduction suggesting lower sympathetic tone in females (β = ?6.64; p < 0.01) and HF.nu showed increase at trend level (β = 4.47; p = 0.053). In conclusion, there is overall reduction in autonomic control of heart with increase in the age. Sympathetic tone predominates and vagal tone diminishes with aging process. Females showed greater vagal tone than male. This differential autonomic tone indicate age, gender related predisposition to cardiovascular disease.