Decreased Heart Rate Variability in Patients with Congestive Heart Failure and Chronotropic Incompetence

Heart rate variability was studied in 41 patients (aged 48 ± 12 years) with congestive heart failure secondary to idiopathic dilated cardiomyopathy. All patients underwent a treadmill exercise test and 24-hour Holter ECC monitoring. Chronotropic incompetence was defined as the failure to achieve > 80% of the predicted maximal heart rate response given by 220 – age (years) at peak exercise. Spectral heart rate variability was analyzed from 24-hour Holter ECCs and was expressed as total (0.01–1.00 Hz), low (0.04–0.15 Hz), and high (0.15–0.40 Hz) frequency components. The standard deviation of all normal RR intervals (SDNN) was also computed. Chronotropic incompetence was observed in ten patients. Peak oxygen consumption was significantly lower in patients witb chronotropic incompetence compared with those without chronotropic incompetence. The total (5.11 ± 1.26 In [ms²] vs 6.41 ± 0.92 In [ms²]; P = 0.009) and low (3.38 ± 1.65 In [ms²] vs 5.45 ± 1.34 In [ms²];P = 0.003), but not the high (3.42 ± 1.04 In [ms²] vs 4.00 ± 1.12 in [ms²]; P = 0.249) frequency components of heart rate variability were significantly lower in patients with chronotropic incompetence, although there was no significant difference in mean heart rate (88 ± 20 beats/min vs 86 ± 15 beats/min; P = 0.831) or left ventricular ejection fraction (22%± 10% vs 24%± 10%; P = 0.619). SDNN was also significantly lower in patients with chronotropic incompetence compared witb those without chronotropic incompetence (64 ± 34 ms vs 102 ± 37 ms; P = 0.030). Conclusions: The observation that heart rate variability is significantly decreased in patients with congestive heart failure who have chronotropic incompetence suggests that chronotropic incompetence may relate to an abnormal autonomic influence on the heart in these patients.     

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。     

Changes in Heart Rate, Heart Rate Variability, and Heart Rate Turbulence during Evolving Reperfused Myocardial Infarction

Depressed cardiac parasympathetic activity is associated with electrical instability and adverse outcomes after myocardial infarction (MI). Heart rate turbulence (HRT), reflecting reflex vagal activity, and heart rate variability (HRV), reflecting tonic autonomic variations are both reduced in the subacute phase of MI. However, the evolution of these components of cardiac autonomic control between subacute and chronic phase of MI has not been defined. We prospectively studied 100 consecutive patients with a recent first MI with ST-segment elevation, who underwent successful direct percutaneous coronary interventions. Beta-adrenergic blockers and angiotensin-converting enzyme (ACE) inhibitors were administered according to the state-of-the-art medical practice guidelines. HRT and HRV were measured from 24-hour ambulatory electrocardiographic recordings 10 days and 12 months after the index MI. There was no significant difference in mean RR interval between the subacute and chronic phase of MI (875 ± 145 versus 859 ± 122 ms). Indices of HRV increased significantly during the observation period (SDNN: from 88.8 ± 26.8 to 116.0 ± 35.7 ms, P < 0.001; SDNNi: from 37.9 ± 15.9 to 46.0 ± 16.3 ms, P < 0.001; SDANN: from 79.6 ± 34.7 to 105.6 ± 35.4 ms, P < 0.001). In contrast, there were no significant changes in indices of HRT (turbulence onset: from −0.008 ± 0.022 to −0.012 ± 0.025%; turbulence slope: from 7.78 ± 5.9 to 8.06 ± 6.8 ms/beat). In contrast to reflex autonomic activity, there was a significant recovery of tonic autonomic activity within 12 months after MI. These different patterns of recovery of reflex versus tonic cardiac autonomic control after MI need to be considered when risk stratifying post-MI patients.     

Heart Rate Variability in Isolated Rabbit Hearts

The presence of heart rate variability (HRV) in patients with cardiac denervation after heart transplantation raised our interest in HRV of isolated, denervated hearts. Hearts from seven adult white ELCO rabbits were transferred to a perfusion apparatus. All hearts were perfused in the working mode and in the Langendorff mode for 20 minutes each. HRV was analyzed in the frequency domain. A computer simulated test ECG at a constant rate of 2 Hz was used for error estimation of the system. In the isolated, denervated heart, HRV was of random, broadband fluctuations, different from the well-characterized oscillations at specific frequencies in intact animals. Mean NN was 423 ± 51 ms in the Langendorff mode, 406 ± 33 ms in the working heart mode, and 500 ms in the test ECG. Total power was 663 ± 207 ms², 817 ± 318 ms², and 3.7 ms², respectively. There was no significant difference in any measure of HRV between Langendorff and working heart modes. The data provide evidence for the presence of HRV in isolated, denervated rabbit hearts. Left atrial and ventricular filling, i.e., the working heart mode, did not alter HRV, indicating that left atrial or ventricular stretch did not influence the sinus nodal discharge rate.     

曲美他嗪对冠心病慢性心力衰竭患者心功能及心率震荡的影响

目的观察曲美他嗪对冠心病慢性心力衰竭患者心功能及窦性心率震荡(HRT)的影响。方法2009 年10 月~2012 年6月经冠脉造影和/或CT血管造影(CTA)证实的73 例冠心病慢性心力衰竭患者,随机分成对照组(n=35)和曲美他嗪组(n=38)。对照组采用常规强心、利尿、扩血管等抗心力衰竭治疗;曲美他嗪组在此基础上给予口服曲美他嗪片。两组分别于服药前和服药3 个月后检查心脏彩色多普勒超声心动图、24 h 动态心电图,测算左心室射血分数(LVEF)、左室舒张末期内径(LVd)以及反映HRT的两个量化指标震荡初始(TO)和震荡斜率(TS)。结果经3 个月治疗,两组LVEF提高,LVd缩小(P<0.01)。曲美他嗪组LVEF改善显著优于对照组(P<0.001)。曲美他嗪组TO和TS均改善(P<0.05),对照组仅TO改善(P<0.05)。曲美他嗪组TO和TS改善均优于对照组(P<0.05)。结论曲美他嗪有助于改善冠心病慢性心力衰竭患者的心功能,改善HRT现象。     

慢性心力衰竭患者心率震荡起始时间分析

目的：研究窦性心率震荡（HRT）的新测量指标震荡斜率起始时间（TT）及HRT测量指标震荡初始（TO）、震荡斜率（TS）在慢性心力衰竭（CHF）患者中的变化,并分析各指标与年龄、室性早搏前心率、联律间期、代偿间期及左房内径（LAD）、左心室舒张末期内径（LVEDD）、左室射血分数（LVEF）之间的相关性。方法：选择79例慢性心力衰竭患者作为CHF组,51例非心脏病患者作为对照组,所有研究对象均经超声心动图测量LAD、LVEDD、LVEF值,同时行动态心电图检查,计算HRT的3个指标：TO、TS、TT,及室性早搏前心率、联律间期、代偿间期。比较CHF组与对照组各指标的差异,并分析HRT各指标与其他指标的相关性。结果：CHF组TT、TO、LAD、LVEDD显著高于对照组,TS、LVEF显著低于对照组。CHF组TO与TS呈负相关（P=0.028）,与LVEF呈负相关（P=0.023）,TS与室性早搏前心率呈负相关（P=0.002）,与室性早搏联律间期（P=0.008）及代偿间期呈正相关（P=0.024）;对照组TO与年龄呈正相关（P=0.009）,与联律间期呈正相关（P=0.049）,TS与室性早搏前心率呈负相关（P=0.006）,与代偿间期呈正相关（P=0.014）;2组TT与其他所有指标间均无显著相关（P〉0.05）。结论：CHF患者HRT明显减弱,其中TT值增大提示患者室性早搏后窦性心率减速现象出现时间延迟,TT有望成为更客观的预测指标。     

慢性充血性心力衰竭患者的心率变异性分析

目的：评价心率变异性在慢性充血性心力衰竭患者中的变化。方法：用24h动态心电图研究慢性充血性心力衰竭患者与对照组的心率变异性及比较其他心脏结构及功能参数。结果：慢性充血性心力衰竭组的SDNN，SDANN，LF，HF，LF／HF均较对照组显著降低（P＜0．05），且随心衰严重程度增加，心率变异性呈递减，并与LVEF，LVEDD及LVSF改变相关（P＜0．05或P＜0．01）。结论：心率变异性可作为了解心衰程度、指导治疗和判定预后的参考指标之一。     

Heart Rate Turbulence after Ventricular Pacing Trains During Programmed Ventricular Stimulation

Background: This study tested the hypothesis that heart rate turbulence (HRT) following ventricular pacing trains depends on train cycle length, presence of retrograde ventriculoatrial (VA) conduction, and left ventricular (LV) function.
Methods: We analyzed digital recordings of programmed ventricular stimulation (PVS) performed in 82 patients (57 men) referred for electrophysiologic studies of ventricular arrhythmias, whose mean age was 64 ± 12 years and LV ejection fraction (EF) was 47 ± 15%. Profiles of sinus RR intervals after all available 8-beat ventricular pacing trains (600-and 400-ms) were averaged. Heart rate turbulence slope (HRTS) was analyzed as the maximum positive slope of a regression line through a sequence of 2–5 (HRTS2 - HRTS5) consecutive RR intervals within the first 5 RR intervals after the pacing train.
Results: Dynamics of RR intervals had biphasic and monophasic patterns, in patients with and without VA conduction, respectively. Sinus nodal response was less prominent after 600-ms than 400-ms pacing trains. After 400-ms pacing trains, HRTS was significantly shallower in patients with LVEF ≤40% than in those with LVEF >40%. HRTS4 was the best discriminator between the two groups (6.8 ± 8.6 ms/RR vs 19.6 ± 26.0 ms/RR, P = 0.017).
Conclusion: In patients with VA conduction, HRT after ventricular pacing trains reflects a combination of vagal withdrawal due to transient hypotension and suppression of sinus node automaticity. Attenuation of vagal modulation was detected in patients with LV dysfunction during standard PVS.     

Heart Rate Variability After Cardiac Transplantation in Humans

The reappearance of cardiac innervation after cardiac transplantation remains a matter of debate. We evaluated the ability of heart rate variability (HRV) analysis to detect the extent and time course of functional cardiac allograft reinnervation. Time- and frequency-domain analysis of heart rate was performed on Holter recordings of 120 heart transplant and four heart-lung transplant recipients. A high frequency (HF) component was clearly distinguished on visual inspection of power spectral density in 42 patients. In eight patients an HF component of normal magnitude was detected. The other 34 patients in this group, including all four heart-lung transplants, presented with a very small HF component. The other 82 patients showed a flat spectrum. The group with an HF component of normal amplitude was significantly different, compared to the other groups, for all HRV parameters. Serial plotting of HRV parameters of the patients with an HF component of normal amplitude against time posttransplant, revealed, from 12 months onwards, a progressive increase of parameters denoting HF variability. In five heart transplant patients with acute allograft rejection, the use of HRV analysis for rejection monitoring was unsuccessful. These results suggest that, inasmuch as the HF component of HRV is caused by parasympathetic cardiac innervation, the HF component of normal amplitude, observed in only a minority of cardiac transplant recipients (6%), is a marker for parasympathetic reinnervation. The evolution over time of this HF component is compatible with a biological phenomenon as gradual parasympathetic reinnervation of the sinus node.     

Heart Rate Turbulence in Chagas Disease

RIBEIRO, A.L.P., et al. : Heart Rate Turbulence in Chagas Disease. Heart rate turbulence (HRT) quantifies the biphasic response of the sinus node to ventricular premature complexes (VPCs) and is a powerful electrocardiogram related risk predictor. VPCs are frequent in Chagas disease, a potentially lethal illness, and can hamper the analysis by conventional methods of autonomic heart control. The aim of the study was to examine HRT in patients with Chagas disease. Chagas disease patients and healthy controls (group   0, n = 11   ) without other diseases were submitted to a standardized protocol, including electrocardiogram, echocardiography, and 24-hour Holter monitoring. Chagas disease patients were divided according to their left ventricular systolic function: normal (group   1, n = 103   ) and reduced ejection fraction (group   2, n = 23   ). Two HRT indices, turbulence onset (TO) and turbulence slope (TS), were calculated and compared among groups after adjustment for covariates like the prevalence of VPCs and the mean heart rate. Chagas disease patients had significantly altered TO (group 1: −0.0186, group 2: −0.0126) and TS (group 1: 10.844, group 2: 7.870) values in comparison with controls (TO − 0.0256, TS 19.829);   P < 0.001   for both comparisons. In conclusion, HRT data may be useful in the electrocardiographic analysis of autonomic heart control in Chagas disease. Its prognostic value remains to be determined. (PACE 2003; 26[Pt. II]:406–410)     

Paradoxical Autonomic Modulation of Atrioventricular Nodal Conduction During Heart Rate Turbulence

WICHTERLE, D., et al .: Paradoxical Autonomic Modulation of Atrioventricular Nodal Conduction During Heart Rate Turbulence. Heart rate turbulence (HRT) represents a biphasic chronotropic response of sinus rhythm to a single ventricular premature beat (VPB). It consists of early acceleration and late deceleration of heart rate and is predominantly mediated by the autonomic nervous system. The aim of this study was to investigate if autonomic perturbations after a VPB exert a significant effect on AV conduction. Both surface ECG and the high right atrial electrogram were recorded at a sampling frequency of 1000 Hz in 26 patients (24 men, mean age 49 ± 12 years) referred for electrophysiological evaluation. The stimulation protocol consisted of series of single ventricular extrastimuli delivered from the right ventricular apex at decreasing coupling intervals. A biphasic profile of AV intervals after a single VPB was observed. The response of AV conduction to a VPB was approximately 25 times and 15 times weaker in the early and late phase, respectively, than that of R-R intervals. Thus, AV interval dynamics significantly preceded the change in R-R intervals, which is in conflict with the near to zero phase of transfer function between R-R and AV intervals described in previous studies. A significant AV turbulence was observed consisting of early shortening and later prolongation of AV intervals after VPB. Its magnitude was much smaller than that of HRT. Dynamics of AV delay has little impact on the accuracy of HRT assessment from surface ECG. The significant temporal dissociation of R-R and AV interval dynamics after a VPB remains unexplained. (PACE 2003; 26[Pt. II]:440–443)     

Heart Rate Variability and Sudden Infant Death Syndrome

PERTICONE, F., ET AL.: Heart Rate Variability and Sudden Infant Death Syndrome. The sudden infant death syndrome (SIDS) is the most common cause of death in infancy. The pathophysiological mechanism leading to SIDS is still obscure. In the QT hypothesis, the mechanism must be an arrhythmogenic sympathetic imbalance: the infants die suddenly of cardiac arrhythmia. Recently, it has been suggested that analysis of heart rate variability (HRV), expressed as standard deviation or variance analysis, can provide adequate information on sympathovagal interaction. We studied 150 newborns enrolled in a previous prospective electrocardiographic study to evaluate the predictive value of QT interval for SIDS. We analyzed the ECGs recorded with infants alert on the fourth day of life and after 2 months. For each ECG, the HRV was calculated using the first standard deviation of of RR intervals (ms) measured for 1 minute. The average RR interval was 441 ± 71 ms at the fourth day and 420 ± 39 ms at the second month. The QT_c and HRV mean values were 396 ± 23 and 23 ± 12 ms at the fourth day, 412 ± 19 and 15 ± 7 msec at the second month. Therefore, the SD values of heart rate were correlated with QT_cin order to assess a possible relationship between the two variables. The correlation coefficient and regression equation were: -0.639 and y = 423.67 - 2.18*× (P < 0.002) at the fourth day, -0.146 and y = 418.09 - 0.37*× (NS) at the second month. In conclusion, our data seems to confirm a delayed maturation or impaired fuctioning of the autonomic nervous system in the first weeks of life, reflecting a direct correlation with QT prolongation.     

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.     

Autonomic Imbalance Assessed by Heart Rate Variability Analysis in Vasovagal Syncope

In this prospective study, the autonomic modulation of the sinus node of 12 patients (mean age 28 ± 7 years) suffering from vasovagal syncope (VVS) was compared to that of 11 sex and age matched control patients (mean age 32 ± 4 years) by analysis of heart rate variability. Spectral indices (low frequency power [Plf], high frequency power [Phf], total power [Pt], sympathovagal balance [LF/HF]) and temporal indices, the mean of all coupling intervals between normal beats (mRR), the standard deviation about the mean (sdRR), the percentage of adjacent R to R intervals differing by more than 50 msec (pNN50), and the root mean square of variations in successive R to R intervals (rMSSD) were compared at baseline and during head-up tilt between and within groups. Baseline results were similar in both groups. During tilt testing, comparison of results between groups revealed only significantly higher sdRR and rMSSD and lower LF/HF ratio in VVS patients. Within WS patients, comparison of temporal and spectral analysis between baseline and tilt showed a significant increase of most indices (Plf, Phf, Pt, sdRR, and rMSSD) but a comparable LF/HF ratio; in contrast, control patients exhibited only a significant increase of LF/ HF ratio. In conclusion. VVS patients who developed vasovagal syncope during head-up tilt demonstrated a nonreciprocal modulation of the sinus node by the autonomic nervous system indicative of a pronounced physiological sympathetic surge along with a paradoxical vagal input to the cardiovascular system.     

抑郁患者的心率变异性分析

目的:对抑郁患者的心率变异性进行分析,评价自主神经张力的改变。方法:选择24例抑郁患者及正常对照组23例,进行HRV分析。结果:抑郁组SDANN、SDNN及rMSSD明显低于对照组,且SDANN均<100ms,LF/HF昼夜节律性变化消失。结论:抑郁患者交感神经张力明显增加,并引起交感神经和副交感神经平衡失常。     

曲美他嗪对慢性心力衰竭患者心率变异性影响的meta分析

目的客观评价曲美他嗪(Trimetazidine,TMZ)对慢性心力衰竭(chronic heart failure,CHF)患者心率变异性(heart rate variability,HRV)的改善效果。方法计算机并手工检索2005年1月—2013年12月Cochrane图书馆临床对照试验库、Pub Med、EMbase、万方数据库、中国知网(CNKI)、中国生物医学文献数据库(CBM)、维普数据库收录的关于TMZ对CHF患者HRV影响的随机对照试验(RCT)研究文献,应用Rev Man 5.0软件对数据进行meta分析。结果本研究共纳入RCT文献10篇CHF共991例,其中常规联合TMZ治疗500例(试验组),单纯常规治疗491例(对照组),文献质量均为中等。meta分析结果显示,与对照组比较,试验组治疗后左室射血分数(LVEF)明显增加,差异有统计学意义(P0.00001);HRV指标中,试验组治疗后正常R-R间期标准差(SDNN)、5 min正常R-R间期均值标准差(SDANN)、连续5 min R-R间期差值均方根(r MSSD)、R-R间期差值大于50 ms的百分比(PNN50)均明显增加或升高,与对照组比较差异均有统计学意义(P均0.00001)。上述各指标漏斗图基本对称,存在发表偏倚可能性小。结论 TMZ联合常规抗心衰治疗CHF效果确切,可显著提高LVEF、HRV,改善患者预后。     

Heart Rate Variability Used as an Arrhythmia Risk Stratifier After Myocardial Infarction

Heart rate variability (HRV) is considered to represent a noninvasive tool to assess cardiac autonomic tone at the level of the sinus node. It has been shown to have predictive power for risk assessment in patients surviving acute myocardial infarction. For this purpose, HRV should be assessed from 24-hour Holter recordings obtained 7–10 days following the infarction. Although there is some recovery of HRV during the first 3 months after infarction, HRV remains reduced in postinfarction patients compared to values obtained in healthy individuals. Compared to assessment of left ventricular function as a risk marker, HRV is superior with respect to prediction of arrhythmic events and sudden death whereas both parameters yield comparative power for prediction of total cardiac mortality. Since the predictive power of HRV analysis alone is relatively low, the combined use of HRV measurements together with traditional risk markers (such as ventricular ectopic beats, signal-averaged ECG, or left ventricular function) results in improved risk prediction with positive predictive accuracy in the range of 30%–50%.