Correlative studies of heart rate and heart rate variability indices from five consecutive ambulatory electrocardiogram recordings in patients with coronary artery disease

Background: Reproducibility of heart rate (HR) and heart rate variability (HRV) indices from ambulatory electrocardiograms (AECGs) is a prerequisite for their use as predictors or monitors of disease progression, or response to therapeutic interventions. Hypothesis: This study sought to determine the stability over time of HR and HRV indices in patients with coronary artery disease. Methods: Five AECGs, recorded at 1-week intervals in 21 clinically stable patients, were used to calculate minimum, average, and maximum HR, and three commonly used HRV indices in data samples of 15,30,60,120, daytime and nighttime intervals (complete data were available on 17 patients). Results: All parameters studied were stable over time (p = NS). Diurnal variation was found only for the average and maximum HR, with values being higher for daytime than for nighttime. Intercorrelations of the HR and HRV indices were poor and varied among the five AECGs, suggesting that these parameters reflect different aspects of HRV. The HR and HRV variables calculated from short-time intervals correlated poorly with the corresponding information from 24-h recordings, and such relationships varied among the five AECGs. Conclusions: Thus, HR and HRV indices from five consecutive AECGs recorded at 1-Week intervals are reproducible. The poor intercorrelations between pairs of the studied indices suggest that none of these parameters can be used as surrogate of the others. Finally, the poor performance of HR and HRV indices, deriving from short-time intervals, indicate that they cannot be employed in lieu of parameters calculated from 24-h AECGs.     

扩张性心肌病患儿心率变异性的预后意义

目的探讨扩张性心肌病(DCM)患儿心率变异性(HRV)变化的预后意义。方法收集42例扩张性心肌病患儿,分成A组心功能Ⅰ～Ⅱ级(NYHA分级,n=20)和B组心功能Ⅲ～Ⅳ级(n=22),以及健康儿童对照组(n=20);采用Mars3000动态心电图仪常规记录24h动态心电图,分析HRV时域参数(SDNN、SDANN、PNN50和rMSSD)和频域参数(TF、VLF、LF、HF、LF/HF)。结果(1)DCM患儿(A组与B组)与对照组比较,各参数差异均有统计学意义(P<0.01);(2)DCM患儿共死亡16例,存活26例,死亡组与存活组各参数比较,t检验有统计学意义。结论HRV可作为评估DCM患儿病情程度的指标,并可作为预后的预测因子。     

Evaluation of the Reynolds Pathfinder II system for 24 h heart rate variability analysis

Heart rate variability (HRV) in 24-h Holter recordings is normallydetermined using commercially available Holter equipment. However,short-term speed variations in tape-based Holter systems havenot been thoroughly investigated and recommendations for speedcontrol are vague. In this study, overall accuracy and precisionof RR interval measurement was assessed for two types of taperecorder replayed on the same Reynolds Pathfinder II system.Artificial QRS complexes spaced at exact intervals were recordedsimultaneously by the two recorders. In addition, records of118 healthy subjects were evaluated for false-positive normal-normalintervals. During replay, digital output from the pathfinderwas processed by a locally developed personal computer-basedHR V system. Using the recorded crystal generated timing track (TT)for speedcontrol and the TT dependent speed surveyor (SS), set to allowspeed errors up to±3·1% mean RR per 5min. h^h–1.24 h^h–1,for test tapes, corresponded exactly to true RR,forboth recorders. Beat-to-beat variation, for 1000 ms test intervals,calculated as standard deviation (SD) and root mean square ofsuccessive differences (RMSSD) was 3 ms, 3 ms versus 5 ins,and 8 ms for Oxford and Tracker tapes respectively. No differencebetween sequential intervals exceeded±10 ms versus ±20ms for Oxford and Tracker respectively. Reproducibility of meanRR and HRV parameters for patient records, expressed as a coefficientof variation, was 0·1–1·7%. False positivenormal-normal intervals>2·3 s, due to artifacts, werefound in 99 of 118 records, and these increased mean SD andRMSSD values significantly, whereas percent successive RR intervaldifferences>50 ms were unaffected. A crystal generated TT (60/16 Hz) and an SS allowing a maximumerror of±31%, together correct speed during recordingand replay to a degree that is acceptable for HRV analysis.A simple estimate of HRV counts of successive RR interval differences>50ms is a reliable param eter as it is relatively insensitiveto artifact.     

Circadian rhythm of the QT interval dispersion in healthy subjects. Correlation with heart rate variability circadian pattern

Circadian variation of QT interval dispersion (QTd) and heart rate variability spectral indices was evaluated in healthy persons in 24-hour 3-lead electrocardiogram. Mean values, SD, and SD/mean were evaluated for 24 hours, each hour separately and in night, day, and morning periods. Table Curve 2D and multiple regression were applied to find correlations between parameters. In 50% of subjects, a significant negative correlation was revealed between QTd and HF. Also, in 50% of persons, a significant positive correlation was found between QTd and low frequency/high frequency. After adjustment for periods, correlations were only observed during morning hours. With Table Curve 2D, 2 models of correlations between QTd and HF were found. Multiple regression analysis revealed relations between mean QTd and R-R as well as mean QTd and HF. It is possible that it is sympathovagal balance, as reflected in heart rate variability, and not the tone of both autonomic components that affects QTd variability.     

Evaluation of the Reynolds Pathfinder II system for 24 h heart rate variability analysis.

Heart rate variability (HRV) in 24-h Holter recordings is normally determined using commercially available Holter equipment. However, short-term speed variations in tape-based Holter systems have not been thoroughly investigated and recommendations for speed control are vague. In this study, overall accuracy and precision of RR interval measurement was assessed for two types of tape recorder replayed on the same Reynolds Pathfinder II system. Artificial QRS complexes spaced at exact intervals were recorded simultaneously by the two recorders. In addition, records of 118 healthy subjects were evaluated for false-positive normal-normal intervals. During replay, digital output from the pathfinder was processed by a locally developed personal computer-based HRV system. Using the recorded crystal generated timing track (TT) for speed control and the TT dependent speed surveyor (SS), set to allow speed errors up to +/- 3.1%, mean RR per 5 min.h-1.24 h-1, for test tapes, corresponded exactly to true RR, for both recorders. Beat-to-beat variation, for 1000 ms test intervals, calculated as standard deviation (SD) and root mean square of successive differences (RMSSD) was 3 ms, 3 ms versus 5 ms, and 8 ms for Oxford and Tracker tapes respectively. No difference between sequential intervals exceeded +/- 10 ms versus +/- 20 ms for Oxford and Tracker respectively. Reproducibility of mean RR and HRV parameters for patient records, expressed as a coefficient of variation, was 0.1-1.7%. False positive normal-normal intervals greater than 2.3 s, due to artifacts, were found in 99 of 118 records, and these increased mean SD and RMSSD values significantly, whereas percent successive RR interval differences greater than 50 ms were unaffected. A crystal generated TT (60/16 Hz) and an SS allowing a maximum error of +/- 3.1%, together correct speed during recording and replay to a degree that is acceptable for HRV analysis. A simple estimate of HRV counts of successive RR interval differences greater than 50 ms is a reliable parameter as it is relatively insensitive to artifact.     

心率变异性减低与老年人心血管事件

目的　评价老年人群心率变异性 (heartrate variability,HRV)减低与心血管事件的关系。方法　回顾性分析我院干部查体 2 4h动态心电图 HRV资料与心血管事件的关系。共 390例。HRV分析包括时域分析和频域分析。时域分析包括正常 RR间期的标准差 (SDNN) ;5 m in平均 RR间期的标准差 (SDANN) ;相邻 RR间期之差的均方根值 (r MSSD) ;爱丁堡指数 (PNN5 0 ) ,频域分析用快速傅立叶转换方法获得心率功率谱密度。并分析总频谱 (TF,0 .0 1～ 0 .5 0 Hz) ,低频 (L F,0 .0 4～ 0 .15 Hz)成分 ,高频(HF,0 .15～ 0 .40 Hz)成分和低频与高频比率 (L F/ HF)。心血管事件包括急性心肌梗死 ,心力衰竭 ,持续性室性心动过速 ,心室颤动 ,心脏性死亡 (包括心脏性猝死 )。比较查体者有和无心血管事件组之 SDNN,SDANN,RMSSD,PNN5 0 ,L F,HF,TF和低频与高频比率 (L F/ HF)有无差别。　结果　有 2 9例老年人发生心血管事件 (n=2 9) ,有心血管事件组之 SDNN为 (91.7± 30 .3) ms,SDANN(84.6± 2 7.9) ms,r MSSD(2 0 .8± 8.8) ms,PNN5 0 (3.8± 5 .0 ) % ,L F(85 .5± 6 9.3) m s2 ,HF(5 2 .1± 35 .5 ) ms2 ,TF(333.3± 2 2 1.2 ) m s2 ,L F/ HF1.6± 1.0。无心血管事件组 (n=36 1)之 SDNN为 (115 .8± 39.2 ) m s,SDANN(10 3.0±     

Standard ECG versus 24-hour holter monitoring in the detection of ventricular arrhythmias

A total of 386 corresponding registrations of standard ECG and 24-h Holter monitoring were compared in order to elucidate the information obtainable from a 60-s standard ECG with regard to ventricular arrhythmias. Ventricular ectopic beats (VEB) were present on 17% of the standard ECGs against 90% of the monitorings (p < 0.001). The corresponding figures for complicated VEB (multiform, repetitive, R on T) were 2% and 41%, respectively (p < 0.001). The presence of VEB on the standard ECG was associated with a significantly increased incidence of all types of ventricular arrhythmias during Holter monitoring performed within the same day. The number of VEBs on the standard ECG did not predict the number during monitoring, but to some extent did predict the occurrence of complicated types. In 52 patients free from VEB on four consecutive standard ECGs, Holter monitoring showed complicated ectopic activity in 32 (62%). Thus standard ECG is an insensitive method for the detection of ventricular arrhythmias.     

老年高血压患者静息心率与心率变异性及动态血压的相关研究

目的探讨老年原发性高血压（EH）患者静息心率（RHR）与心率变异性（HRV）及动态血压的关系。方法106例老年EH患者根据RI-IR水平分为：A组60例,RHR〈80次／min;B组46例,RHR〉80次／min。对入选患者同步监测动态心电图及动态血压,对比分析HRV及动态血压参数的变化。结果B组HRV时域指标SDNN、SDANN、RMssd、PNN50及TI低于A组,而动态血压各参数均高于A组,差异有统计学意义（P〈0．05,P〈0．01）。RHR与HRV指标SDNN、SDANN及TI呈负相关,而与DBP呈正相关（P〈0．05,P〈0．01）。结论RHR增快是老年EH患者的一个危险因子,与HRV降低、血压增高相关密切。     

Heart rate, PR, and QT intervals in normal children: a 24-hour Holter monitoring study

A dynamic electrocardiographic Holter monitoring study was performed in 32 healthy children (20 males and 12 females, age range 6-11 years old), without heart disease, according to clinical and noninvasive instrumental examination. We evaluated atrioventricular conduction time (PR), heart rate (HR), and QT interval patterns defining the range of normality of these electrocardiographic parameters. The PR interval ranged from 154 +/- 10 ms (mean +/- SD) for HR less than or equal to 60 to 102 +/- 12 ms for HR greater than or equal to 120 (range 85-180). The absolute mean HR was 87 +/- 10 beats/min (range 72-104), the minimum observed HR being 61 +/- 10 (range 51-79), the maximum 160 +/- 20 beats/min (range 129-186). Daytime mean HR gave a mean value of 93 +/- 10 (range 71-148), while during night hours it was 74 +/- 11 (range 54-98). The minimum QT interval averaged 261 +/- 10 ms for HR greater than 120 and the maximum 389 +/- 9 ms for HR less than or equal to 60; the corresponding mean value of QTc (i.e., QT corrected for HR) ranged from 388 +/- 8 for HR less than or equal to 60 beats/min to 403 +/- 14 ms for HR greater than 120 beats/min. The results of the present study provide data of normal children which can be readily compared against those of subjects in whom cardiac abnormalities are suspect or patient.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circadian pattern of heart rate variability in chronic heart failure patients Effects of physical training

The effect of physical training on the circadian pattern ofheart rate variability (recorded over 24 h in relation to bothtime and frequency) was assessed in 12 chronic heart failurepatients randomized, in a cross-over design, to 8 weeks trainingor detraining, and compared with 12 age-matched normals. Trainingimproved heart rate variability indices: all R-R interval 5min standard deviations increased by 17.6%, the root mean squareof the differences of successive R-R intervals by 34.9%, thepercentage difference between adjacent normal RR intervals>50ms by 112.5%, total power by 58.3%, high frequency by 128.5%and low frequency by 65.0%. Compared with controls, circadianvariations in autonomic parameters were maintained in chronicheart failure. Training-induced changes were observed at differenttime intervals throughout the day: the highest values were at0100 h-0700 h (detraining: low frequency 361±83 ms²,high frequency 126±47 ms²; training: low frequency 535±202ms², high frequency 227±115 ms², P<0.01) and the lowestat 1300 h-1900 h (detraining: low frequency 91±23 ms²,high frequency 39±14 ms²; training: low frequency 154±42ms², high frequency 133±67 ms², P<0.05). In chronicheart failure, training maintains and improves circadian variationsin heart rate variability measures.     

Physical activity is a major contributor to the ultra low frequency components of heart rate variability

OBJECTIVE—To investigate the link between changes in level of physical activity and the pattern of heart rate variability during long term ambulatory monitoring.
DESIGN—Heart rate variability was measured simultaneously with a quantitative indicator of muscle activity by electromyography (EMG) in five men and five women while they did activities typical of daily life or while they rested for 2-3 hours. Spectral and cross spectral analyses were performed on both variables with standard fast Fourier transform.
RESULTS—There was a marked reduction in spectral power in the ultra low frequency band (< 0.003 Hz) on going from active to rest conditions for both heart rate variability (men 6187 (1801) v 410 (89) ms²/Hz; women 4056 (1161) v 2094 (801), mean (SEM); p < 0.01) and EMG (p < 0.001). Cross spectral analysis showed a strong positive gain between the EMG and heart rate variability signal that was virtually eliminated in the resting condition (p < 0.01). A sex-by-condition effect (p = 0.06) was noted with a reduction in total spectral power for heart rate variability during rest in men, while it increased slightly in women.
CONCLUSIONS—There is a quantitative link between muscle activation and heart rate variability in the lowest frequency band. Voluntary restriction of physical activity in healthy young subjects caused marked reduction in spectral power in the lowest frequency band which is often used to assess patient prognosis. The findings strongly suggest that studies of ambulatory heart rate variability should always include an indication of physical activity patterns.


Keywords: spectral analysis; electromyography; Holter monitoring; sex effect     

Enhanced detection of abnormalities in heart rate variability and dynamics by 7‐day continuous ECG monitoring

BackgroundThe analysis of heart rate variability (HRV) and heart rate (HR) dynamics by Holter ECG has been standardized to 24 hs, but longer‐term continuous ECG monitoring has become available in clinical practice. We investigated the effects of long‐term ECG on the assessment of HRV and HR dynamics.MethodsIntraweek variations in HRV and HR dynamics were analyzed in 107 outpatients with sinus rhythm. ECG was recorded continuously for 7 days with a flexible, codeless, waterproof sensor attached on the upper chest wall. Data were divided into seven 24‐h segments, and standard time‐ and frequency‐domain HRV and nonlinear HR dynamics indices were computed for each segment.ResultsThe intraweek coefficients of variance of HRV and HR dynamics indices ranged from 2.9% to 26.0% and were smaller for frequency‐domain than for time‐domain indices, and for indices reflecting slower HR fluctuations than faster fluctuations. The indices with large variance often showed transient abnormalities from day to day over 7 days, reducing the positive predictive accuracy of the 24‐h ECG for detecting persistent abnormalities over 7 days. Conversely, 7‐day ECG provided 2.3‐ to 6.5‐fold increase in sensitivity to detect persistent plus transient abnormalities compared with 24‐h ECG. It detected an average of 1.74 to 2.91 times as many abnormal indices as 24‐h ECG.ConclusionsLong‐term ECG monitoring increases the accuracy and sensitivity of detecting persistent and transient abnormalities in HRV and HR dynamics and allows discrimination between the two types of abnormalities. Whether this discrimination improves risk stratification deserves further studies.     

高血压并冠心病者心率减速力与HRV的相关性

目的 探讨高血压合并冠心病患者心率减速力(DC)与心率变异性(HRV)的相关性.方法 选择36例窦性心律的高血压合并冠心病患者和40例正常人对照组,进行24h动态心电图检查,应用国内自行研制的DC处理软件,离线计算DC、HRV时域指标.结果 高血压合并冠心病组的DC、HRV降低;且DC与时域指标SDNN、RMSSD、P...     

Effects of cigarette smoking on ambulatory blood pressure,heart rate,and heart rate variability in treated hypertensive patients

We investigated the influence of cigarette smoking on the levels and circadian patterns of blood pressure (BP), heart rate (HR), and HR variability (HRV) in hypertensive patients. Sixteen hypertensive smokers (57 ± 2 years old) receiving antihypertensive treatments participated in this study. Ambulatory monitoring of BP, HR, and electrocardiograms was performed every 30 min for 24 hours on a smoking day and nonsmoking day in a randomized crossover manner. Average 24-hour BP and daytime BP were significantly higher in the smoking period than in the nonsmoking period. No significant differences were observed in nighttime BP between the two periods. Average 24-hour and daytime HR, but not nighttime HR, were also higher in the smoking period than in the nonsmoking period. The daytime high frequency (HF) component of HRV was attenuated more in the smoking period than in the nonsmoking period. No significant differences were observed in the low frequency (LF) components of HRV or LF/HF ratio between the two periods. These results demonstrated that cigarette smoking increased the daytime and average 24-hour BP and HR, and the increases observed in daytime BP and HR were associated with the attenuation of parasympathetic nerve activity.     

鼻咽癌患者放射治疗后动态心电图及QT离散度和心率变异性改变的探讨

目的：探讨鼻咽癌患者放射治疗后动态心电图、QT离散度和心率变异性（HRV ）的变化情况。方法对40例鼻咽癌患者治疗前及接受3个阶段不同放射剂量（分别为15～25 Gy、35～45 Gy和55～65 Gy）的放射治疗后（每一个治疗阶段均行动态心电图监测）,观察放射治疗致心电图及QT离散度（QTd）、校正后QT离散度（QTcd）和HRV时域指标及频域指标改变的情况。结果鼻咽癌患者放疗前和3个阶段放射治疗后动态心电图各项指标比较：（1）室上性心律失常、室性心律失常和ST-T改变的发生率比较,差异均无统计学意义（P＞0．05）;（2）QTd、QTcd指标比较,差异均无统计学意义（P＞0．05）;（3）HRV分析比较,①时域指标SDNN、rMSSD、pNN50差异均无统计学意义（P＞0．05）;②频域指标TP、LF、HF、LF/HF差异均无统计学意义（P＞0．05）;两两比较后,VLF在3个阶段放射治疗后显著低于放疗前,差异有统计学意义（P＜0．05）。结论（1）室性心律失常和ST-T改变的发生率的变化趋势相似,即放射剂量为15～25 Gy时呈上升趋势、35～45 Gy时呈下降趋势、55～65 Gy时呈明显上升趋势;（2）QTd、QTcd指标在放射剂量为15～25 Gy时呈下降趋势、35～45 Gy时呈上升趋势、55～65 Gy时恢复到治疗前水平;（3）HRV指标中,随着放射剂量的增加,VLF的降低更加显著,提示鼻咽癌患者放疗后影响了体温调节、肾素血管紧张素系统及体液因子等因素的长期调节,引起交感神经活动增强,影响交感-迷走神经之间的均衡性,从而影响自主神经调节,导致心电图异常。