低压舱减压前后心率变异性的变化特征

目的 旨在探讨缺氧与心率变异性(HRV)的相关性。方法 受试者为12名非医学原因停飞的初教机飞行学员。在低压舱减压前、减压至5000 m即刻、10 min、20 min、30 min和下降至地面水平后即刻各测5 min标准Ⅱ导联心电图。结果 在缺氧状态下,11名受试者均出现心率加快、HRV降低;下降至地面水平后即刻心率恢复正常,HRV增大。1例受试者在缺氧7 min时出现血管迷走性晕厥先兆,终止试验。结论 采用缺氧状态下HRV检测,能较客观地反映心脏自主神经功能。     

心率变异评价心肌梗死患者自主神经功能临床研究

心率变异 (HRV)指窦性心率在一定时间周期性改变的现象 ,是反映交感神经与副交感神经张力及平衡的重要指标 ,研究表明 ,许多心血管疾病 ,如冠心病、高血压病、充血性心功能衰竭等都表现出明显的HRV改变[1] ,另外有人报道HRV可以作为预测心源性猝死的独立指标[2 ] 。因此 ,心肌梗死患者HRV的评价可能对临床工作有一定的指导意义。材料和方法一、病例选择我院 1998年 5月至 2 0 0 2年 7月期间HRV检查心肌梗死患者 16 7例 ,AMI组 6 0例 ,男 39例 ,女2 1例 ,年龄 35～ 75岁 ,平均 (5 5± 5 )岁。诊断符合WHO标准。于发病 72h内行HRV检…     

高压氧治疗对急性心肌梗死康复期Q-T离散度及心率变异性的影响

目的 观察高压氧(HBO)治疗对急性心肌梗死(AMI)患者康复期Q-T离散度及心率变异性的影响.方法 AMI 1个月以上符合Ⅰ期心脏康复条件的患者80例,将其分为2组,治疗组40例,给予HBO治疗辅以基础治疗;对照组40例,只给予基础治疗.HBO治疗15 d后比较2组患者Q-T间期离散度及心率变异性的变化.结果 HBO治疗组最大Q-T间期变小,Q-T离散度变小,心率变异性增大,交感神经活动下降,迷走神经张力增加.结论 HBO治疗有利于AMI康复期患者加快心电活动的恢复.     

冠心病合并焦虑障碍患者心率变异性的变化临床研究

目的 探讨冠状动脉粥样硬化性心脏病(coronary heart disease,CHD)合并焦虑障碍患者心率变异性(heart rate variability,HRV)的变化.方法 73例经选择性冠状动脉造影确诊为CHD的住院患者,通过医院焦虑抑郁量表(hospital anxiety and depression scale,HADS)的焦虑亚量表评分,分为焦虑障碍组(焦虑组,41例)和对照组(不伴焦虑障碍,32例),运用动态心电图系统采集患者的心电信号进行HRV分析.结果 与对照组比较,合并焦虑障碍的CHD患者HRV指标SDNN、rMSSD、PNN50明显降低,具有统计学差异(P<0.05),而焦虑评分与CHD患者冠脉病变程度无明显相关性,焦虑与焦虑状态比较HRV指标无统计学差异.结论 冠心病合并焦虑症患者更容易引起心率变异性降低,交感神经兴奋增强,有可能增加心源性猝死概率;同时,抗焦虑治疗对预防心源性猝死可能有效.     

交感神经型颈椎病对心率变异性影响的临床研究

 目的 为交感神经型颈椎病的诊断和治疗提供一项新的无创性量化诊断标准。方法 应用24h动态心电图测定25例交感神经型颈椎病患者的心率变异指标,并分白天和夜间2个时段与25例年龄、性别配对的正常人比较。结果 交感神经型颈椎病和对照组MHR、MeanRR(白天时段)、LF／HF 3项指标比较无显著性差异(P＞0.05);其余2个时段指标MeanRR(夜间时段)、SDNN、SDANN、rMSSD、PNN50两组相比较,颈椎病组明显降低(P＜0.05)。病例组2个亚型间心率变异性(Heartrate variability,HRV)分析指标比较表明,激惹型与麻痹型MHR、MeanRR、LF／HF有显著性差异(P＜0.05)。50例受检者的Lorenz散点图表明,慧星状、非慧星状2组构成比差异有非常显著意义(x~2=26.087,P＜0.01)。结论 交感神经型颈椎病患者心率变异性降低,表明植物神经功能受损,其中颈交感神经激惹型患者交感神经张力升高,颈交感神经麻痹患者交感神经张力降低,该型患者迷走神经功能也有部分受损。此结论为交感神经型颈椎病患者的治疗提供了客观和量化参数。     

间断性短臂离心机+Gz暴露联合运动锻炼对心血管自主神经调节功能的影响

目的 利用短臂离心机进行梯度G值联合运动负荷锻炼,观察间断性锻炼3周后人体心血管自主神经调节功能的变化.方法 8名健康青年男性间断进行离心机梯度G值(1～2 G)暴露联合30 W运动负荷锻炼,每天30 min,持续3周.记录心电图和逐跳连续血压,运用自回归谱分析法得到心率变异性(HRV)与收缩压变异性功率谱.锻炼前后进行头高位倾斜联合下体负压测试,观察立位应激时心血管功能变化.结果 在卧位休息时,锻炼3周后被试者HRV的低频与高频比值较锻炼前显著下降(P＜0.05),收缩压变异性的低频功率较锻炼前显著增加(P＜0.05).在头高位倾斜联合下体负压实验时,锻炼后被试者心率较锻炼前显著下降(P＜0.05),总外周阻力显著增加(P＜0.05),每搏量呈增加的趋势.结论 离心机+Gz暴露联合30 W运动锻炼3周可以增加平卧位心脏迷走神经与外周血管交感神经活动水平,增强立位应激时血压调节能力,提高了心血管功能储备.     

冠状动脉狭窄程度对冠心病患者心率变异性的影响

目的探讨冠心病患者冠状动脉病变狭窄程度对心率变异性(HRV)的影响及其临床意义。方法:将经冠状动脉造影证实冠状动脉管腔狭窄≥50%～70%定为中度狭窄组46例,>70%以上定为重度狭窄组41例,正常对照组38例,术前行24h动态心电图,计算HRV时域指标。结果:中、重度狭窄组HRV指标中SDNN、SDANN均显著低于正常对照组(P<0.01),重度狭窄组HRV指标中SDNN、SDANN显著低于中度狭窄组(P<0.01)。结论:冠心病患者HRV的降低与冠脉病变狭窄程度有关,提示HRV可作为预测冠心病严重程度和预后的重要指标。     

环境大气压变化对年轻健康人心率及短程心率变异性影响的研究

目的 探讨环境大气压变化对年轻健康人心率(HR)及短程心率变异性(HRV)的影响.方法 利用高压舱结合动态心电图对40例年轻健康人进行临床试验,记录升压前、升压过程中、高压状态、减压过程中及减压后各5 min的平均心率及全部窦性心搏N-N间期标准差(SDNN)、相邻N-N间期差值均方根(RMSSD)、相邻N-N间期相差＞50瑚占窦性心律百分数(PNN50)3项短程心率变异性时域指标,并进行统计学处理.结果 环境大气压升高可使心率减慢,升压前(87.28±12.77)次/min,升压过程中(76.08±10.74)次/min,高压状态(75.30±12.06)次/min,升压前后比较差异有统计学意义(P＜0.01);随着大气压的回落,心率逐渐加快,但未恢复到升压前水平;主要反映交感和迷走神经总张力的心率变异性指标要SDNN和主要反映迷走神经张力的RMSSD、PNN50基本上随着环境大气压升高而升高,随着大气压降低而降低.结论 环境大气压的变化对心率和心率变异性有较明显的影响,当环境气压较快降低时,心血管的自主神经功能会被扰乱.     

肾脏病患者心率变异性的临床观察

目的 :用心率变异性 (HRV)分析技术观察肾脏病及肾功不全患者的HRV指标变化。方法 :用 2 4h动态心电图分析HRV的时域指标。观察肾功正常的肾病患者 2 6例 ,肾功不全患者 34例 ,正常对照 34例。结果 :肾功正常肾病组RRI 76 3.0 5±10 4.2 1、SD 12 2 .48± 39.82、SDAIDX 111.87± 40 .6 0 ,均显著低于正常组 ,P <0 .0 5 ;肾功不全组六项指标均明显低于正常对照组 ,SD 76 .0 9± 37.70 ,SDAIDX 6 7.74± 34.47,SDIDX 2 9.5 9± 15 .37,及rMSSD 17.85± 9.35显著低于肾功正常组。结论 :肾脏病患者在肾功正常期即有自主神经功能损伤 ,以交感神经活动受损为主 ,肾功不全患者交感神经及迷走神经功能均受损。     

心率变异性指标在心血管疾病中的应用

心率变异性（HRV）是指逐次心跳间期之间的微小差异，可评价心脏迷走神经和交感神经活动的紧张性、均衡性及其对心血管活动的影响。指标中PNN50（相邻窦性R-R间期差值〉50ms的百分比），rMSSD（24h的R-R连续差异均方的平方根）和高频与迷走神经活动有关，低频和SDANN（5min窦性R-R间期均值的标准差）主要与交感神经有关。     

Autonomic adaptations in andean trained participants to a 4220-m altitude marathon

PURPOSE: Both training and chronic hypoxia act on the autonomic nervous system. Because trained Andean high-altitude natives could perform a high-altitude marathon (4220 m above sea level) in 02:27:23 h, we hypothesized that living in chronic hypoxia does not limit the training-induced benefits on the autonomic modulation of the heart. METHODS: Trained (N=13) and sedentary (N=11) Andean high-altitude natives performed an active orthostatic test. Eight of the trained subjects repeated the test 6-8 and 20-24 h after the end of a high-altitude marathon. Resting heart rate (HR) and the autonomic modulation of the heart were assessed by time domain and spectral analysis of HR variability (HRV): sympathetic (RR low frequency (LF)) and parasympathetic (RR high frequency (HF)) modulations, and sympathovagal balance (RR-LF:HF ratio). RESULTS: Trained subjects exhibited a higher total power of HRV and a lower resting HR (+30%, P<0.005) than sedentary subjects secondary to a higher and dominant parasympathetic modulation on sympathetic activity (RR-HF, RR-LF:HF ratio). At 6-8 h after the marathon, total power of HRV decreased (-69%), whereas resting HR increased from basal level (+22%), mainly because of a rise in sympathetic modulation (RR-LF, RR-LF:HF ratio). From 8 to 24 h of recovery, sympathetic modulation fell (RR-LF, RR-LF:HF ratio) and all HRV parameters were restored. Responses to the active standing position did not change between each recording session. CONCLUSION: Living in chronic hypoxia does not limit the training-induced benefits on the autonomic control of the cardiovascular system in Andean high-altitude natives. The sympathetic predominance on the heart observed 6-8 h after the high-altitude marathon disappeared after 1 d of recovery. Therefore, living at high altitude does not impair the autonomic response to training.     

Acute resistance exercise reduces heart rate complexity and increases QTc interval

Acute resistance exercise (RE) has been shown to reduce cardiac vagal control. Whether this would in turn affect QTc interval (an index of ventricular depolarization/repolarization) or heart rate complexity is not known. Heart rate variability (HRV), heart rate complexity (SampEn), and QT interval (rate corrected using Bazett, Fridericia, Hodges, and Framingham) were measured before and 5 min after an acute RE bout in twelve healthy young men. Normalized high frequency power of HRV (an index of cardiac parasympathetic modulation; HF (nu)), and SampEn were reduced following RE (p < 0.05). Bazett corrected QTc interval increased following RE (p < 0.05). Change in HF (nu) from rest to recovery was correlated with both change in SampEn (r = 0.51, p < 0.05) and change in QTc interval for each method of correction (r = - 0.67 to - 0.70, p < 0.05). Acute RE reduced HF spectral power of HRV and this was related to both reduced heart rate complexity and increased QTc length. Thus, during recovery from acute RE, there is prolongation of depolarization and repolarization of the ventricles concomitant with reduced cardiac irregularity, and this may be related to a reduction in cardiac vagal control.     

Effects of severe hyperbaric pressure on autonomic nerve functions

Autonomic nerve functions under severe hyperbaric pressure were evaluated by measuring heart rate variability (HRV) and catecholamine excretion rate in 16 normal volunteers in submarine experimental facilities simulating conditions 330 m below sea level. HRV and urinary catecholamine levels were evaluated to assess sympathetic and parasympathetic tone. High-frequency HRV increased from 5.6 +/- 1.3 to 6.3 +/- 1.4 ms2 (p < 0.05), and SD of the average normal R to R intervals for 5-minute index (SDNNI) (time domain HRV parameter) increased from 77.2 +/- 32.7 to 93 +/- 33.8 ms (p < 0.05) after 3 days. Adrenaline/creatinine increased by 18% from a basal value of 4.04 +/- 0.44 ng/dL/h. Also, there was significant negative correlation between high-frequency and urinary cathecholamine levels. Evaluation of autonomic nerve functions under hyperbaric conditions by measuring HRV was shown to be a useful method. Thus, the present results indicate that the autonomic nerve functions of people who work under deep-sea conditions can be evaluated adequately by measuring HRV.     

Pre- and post-season heart rate variability in adolescent cross-country skiers

To investigate the effects on cardiac autonomic control after a competitive cross-country skiing season, 9 females and 8 males, 16-19 years old, performed tilt-table heart rate variability (HRV) recordings and incremental treadmill tests before (August), and after (April the following year) the most intensive period of training and competition. Spectral analysis of HRV showed increased total variability at rest and reduced low frequency variability in the tilted position (LFtilt) at the second test (P<0.05). The female subgroup showed consistently higher high frequency (HF) and total heart rate variability than males. Total run time (RunT) increased from 18.5+/-1.9 min to 19.4+/-1.7 min (mean+/-SD) in the entire group (P<0.05), while VO2max only showed a non-significant increase (0.05相似文献   

卧床中及卧床后头高位倾斜对心率及血压变异谱的变化

观察了男性青年２１ｄ头低位６°卧床过程中以及卧床前、后７５°头高位倾斜（ＨＵＴ）时心率变异（ＨＲＶ）与动脉收缩压变异（ＳＢＰＶ）谱变化。卧床期间，完成者ＨＲＶ和ＳＢＰＶ谱的低，高频谱峰功率（ＬＦ和ＨＦ）均显著减小，ＨＲＶ谱低，高频谱峰功率比值（ＬＦ：ＨＦＨＲＶ）在卧床第１６ｄ有增大趋势，未完成者的相应谱指标有类似变化趋向，在卧床后ＨＵＴ初始６ｍｉｎ，所有被试者心率显著快于卧床前ＨＵＴ时相应值，而Ｌ     

Post-exercise heart rate variability of endurance athletes after different high-intensity exercise interventions

Methodological problems have limited the number of studies on heart rate variability (HRV) dynamics immediately after exercise. We used the short-time Fourier transform method to study immediate (5 min) and slow (30 min) recovery of HRV after different high-intensity exercise interventions. Eight male athletes performed two interval interventions at 85% and 93% (IV₈₅ and IV₉₃) and two continuous interventions at 80% and 85% (CO₈₀ and CO₈₅) of the velocity at VO_2max (vVO_2max). We found no increase in high frequency power (HFP), but low frequency (LFP) and total power (TP) increased ( P <0.05) during the first 5 min of the recovery after each intervention. During the 30-min recovery, HFP, LFP and TP (1) increased slowly toward resting values, but HFP remained lower ( P <0.01) than at rest, (2) were lower ( P <0.05) after IV₉₃ and CO₈₅ when compared with IV₈₅ and CO₈₀, respectively and (3) were lower ( P <0.01) after CO₈₅ when compared with IV₈₅. HRV recovery was detected during the immediate recovery after interventions. Increased exercise intensity resulted in lower HRV both in interval and in continuous interventions. In addition, when interval and continuous interventions were performed at a similar workload, HRV was lower after continuous intervention.     

Effects of a single bout of exercise on resting heart rate variability

PURPOSE: Chronic exercise training has been shown to have a positive influence on cardiac autonomic function as assessed by measures of heart rate variability (HRV). Recent evidence indicates that several benefits associated with exercise training (e.g., improved insulin action, reduced blood pressure, improved blood lipid profile) may be realized transiently after a single bout of exercise. As many of these effects of recent exercise are linked to cardiovascular control systems, the purpose of this investigation was to test the hypothesis that a single bout of exercise would result in favorable changes in cardiac autonomic function as assessed by frequency-domain measures of HRV. METHODS: Subjects were 11 healthy male volunteers ages 18-35 yr. Resting HRV measures were obtained during 5 min of paced breathing before and 1, 3, 6, and 22 h after a 60-min bout of cycling exercise at approximately 65% of peak oxygen uptake. Identical measures were obtained in a nonexercise condition based on a randomized crossover design. RESULTS: Exercise resulted in increased high-frequency HRV, decreased low-frequency HRV, and consequently a decrease in the ratio of low-frequency to high-frequency HRV compared with the nonexercise condition. Additionally, a time-domain measure of HRV (pNN50) was markedly higher in the exercise condition as compared to nonexercise. CONCLUSION: The changes in cardiac autonomic function observed are similar to those seen in investigations of long-term training. These changes indicate a shift in autonomic function toward increased parasympathetic nervous system activity and decreased sympathetic nervous system activity, suggesting a more stable autonomic environment for the heart. These results may provide further evidence of the cardioprotective effects of a single bout of submaximal exercise.     

Heart rate variability of recently concussed athletes at rest and exercise

PURPOSE: The objective of this study was to assess the neuroautonomic cardiovascular regulation in recently concussed athletes at rest and in response to low-moderate steady-state exercise, using heart rate variability (HRV). METHODS: A 5-min ECG sample was taken at rest from the 14 concussed athletes at 1.8 (+/- 0.2) days postinjury and again at 5 d later. Once asymptomatic at rest, the concussed athletes and their matched controls (N = 14) participated in an exercise protocol. The protocol consisted of a 2-min warm-up with a pedaling frequency between 50 and 60 rpm against a load of 40 W. After the warm-up, the athletes engaged in a low-moderate intensity steady state 10-min exercise bout where the pedaling frequency and load increased to 80-90 rpm and 1.5 W x kg(-1) body weight, respectively. The protocol was repeated 5 d later. A 5-min ECG sample from minutes 4 to 9 of the low-moderate intensity steady state exercise bout was used to assess HRV during exercise. Mixed model ANOVA were used to analyze the data. RESULTS: No difference at rest was detected between the concussed athletes and their matched controls in any of the HRV variables measured. However, across both exercise tests, the concussed group demonstrated a significant decrease in the mean RR interval, and low- and high-frequency power (P < 0.05) in relation to their matched controls. CONCLUSION: Low-moderate steady-state exercise elicits a neuroautonomic cardiovascular dysfunction in concussed athletes that is not present in a rested state. This dysfunction alludes to an exercise induced uncoupling between the autonomic and cardiovascular systems.     

X综合征与冠心病心率变异性的对比分析

为比较X综合征和冠心病患者心率变异性指标的异同,探讨X综合征自主神经变化的临床意义,选择X综合征患者、冠心病患者、正常对照各12例,测定了时域和频域指标,分析X综合征的心率变异参数,并与冠心病和正常对照组进行对比。结果表明,X综合征组和冠心病组各时段心率变异指标均低于对照组,X综合征与冠心病对比,夜晚RMSSD、清晨LF／HF和VLF差异有显著性（P＜0.05）。提示X综合征患者存在心血管自主神经系统调节功能紊乱现象,以交感神经活动占优势;心率变异分析可作为观察X综合征自主神经变化和指导临床治疗的指标。     

Changes in cardiac autonomic activity during a passive 8 hour acute exposure to 5 500 m normobaric hypoxia are not related to the development of acute mountain sickness

Alterations in the autonomic nervous system after ascent to high altitude may be related to the development of acute mountain sickness (AMS). So far, the time course of cardiac autonomic modulation in relation to AMS development during the early hours at altitude is not well established. As AMS develops sometimes as early as 1 h and typically within 6 to 10 h at altitude, evaluating this time period provides information on cardiac autonomic responses with regard to AMS development. Prior studies exclusively investigated autonomic modulations in hypobaric hypoxia. Because barometric pressure per se might influence autonomic nervous system activity, the evaluation of cardiac autonomic alterations caused by hypoxia alone might give new insights on the role of the autonomic nervous system in AMS development. To assess the early responses of acute hypoxia on cardiac autonomic modulation and its association to the development of AMS, 48 male subjects were exposed for 8 h to acute normobaric hypoxia (FiO2 11.0%, 5?500 m respectively). Heart rate variability (HRV) was determined by 5-min recordings of successive NN-intervals in normoxia and after 2, 4, 6 and 8 h in hypoxia. Compared with normoxia, acute exposure to hypoxia decreased total power (TP), high frequency (HF) and low frequency (LF) components as well as the standard deviation of all NN intervals (SDNN), the root mean square of differences of successive NN intervals (rMSSD) and the proportion of differences between adjacent NN intervals of more than 50 ms (pNN50). LF:HF ratio, heart rate (HR) and blood lactate (LA) were augmented, indicating an increase in cardiac sympathetic activity. No differences were found between those who developed AMS and those who did not. Our results confirm reduced HRV with a shift towards sympathetic predominance during acute exposure to hypoxia. However, changes in cardiac autonomic modulations are not related to AMS development in acute normobaric hypoxia.