750例健康儿童心率变异性分析

Objective To investigate the range of normal values of heart rate variability (HRV) in 750 healthy children,and to explore the relationship between the value of HRV and age. Methods A total 750 healthy children were randomly divided into six groups according to their ages as follows: group Ⅰ ( less 1 month), group Ⅱ ( 1 month to 1 years old), group Ⅲ ( 1 to 3 years old), group Ⅳ (3 to 6 years old), group Ⅴ (6 to 11 years old)and group Ⅵ( 11 to 16 years old). HRV time domain value(SDNN、SDANN、PNN50、rMSSD)and spectral power value( TF、VLF、LF、 HF、LF/HF)were measured by 24 dynamic electrocardiogram in all children. Results (1)The HRV time domain values( SDNN 、SDANN、rMSSD)were increased with age, there were significant differences among six groups ( P ＜ 0.05 and P ＜ 0. 01 ). ( 2 ) The spectral power values ( TF、VLF、LF、HF) comparison showed significant differences among six groups( P ＜0. 05 and P ＜0. 01 ). Conclusion HRV varies significantly with age, and it increases with age in children. The values generated in this study may be useful in determining abnormal ranges of HRV.     

Heart rate variability in normotensive healthy children with aging

Although the heart rate variability (HRV) values in adults decrease with aging, those in children show a variety of changes. The present study was designed to investigate the relationship between HRV and aging, physique and blood pressure in 70 healthy male school children, between 6 and 12 years of age. The subjects were divided into 3 age groups (6-7, 8-9 and 10-12 years) and 3 other groups according to physique (thin, under -10%; normal, -10-20% and obese, over 20% of obesity index). After recording a 24-h ambulatory electrocardiograph, HRV was determined spectrally, using 3 components: the total-frequency (TF) component (0.01 to 0.5 Hz), the low-frequency (LF) component (0.04 to 0.15 Hz), the high-frequency (HF) component (0.15 to 0.5 Hz) and also a two component ratio (LF/HF). The HRV values between the 3 age groups had a significant effect on TF, LF and LF/HF during the 24-h period, with the values increasing with age. The HRV values between the 3 physique groups had no significant effect. Therefore, changes in HRV in school children are affected by age and not physique. It is possible that the increase in HRV values with age is caused by the development of the autonomic nervous system.     

750例健康儿童心率变异性分析

目的对750例健康儿童心率变异性（heart rate variability,HRV）进行分析,观察正常值范围及HRV与年龄的关系。方法对750例来我院体格检查的正常健康儿童分为以下6个年龄组：新生儿组（〈1个月）、婴儿组（1个月一1岁）、幼儿组（1～3岁）、学龄前组（3～6岁）、学龄组（6—11岁）和青春期组（11—16岁）,进行24h动态心电图检测,分析HRV时域（SDNN、SDANN、PNNSO、rMSSD）及频域（TF、VLF、LF、HF、LF／HF）结果。结果（1）各年龄组HRV时域分析SDNN、SDANN、rMSSD差异有统计学意义（P〈0．05或P〈0．01）,随年龄增长,HRV有增大趋势。（2）HRV频域分析TF、VLF、LF、HF差异有统计学意义（P〈0．01）,数值随年龄增大而增大。结论不同年龄段HRV时域及频域结果不同,HRV随年龄增加而增大,可对临床研究异常HRV提供参考依据。     

Heart rate variability in healthy newborn infants.

In adults and older children, heart rate variability (HRV) is frequently used to study autonomic function noninvasively. Normal values of HRV in newborn infants, however, are not widely available. This problem may be partially attributed to the lack of standardization of different methods. This study assessed HRV in normal newborn infants using 24-hour Holter monitoring. From 1997 to 2000, we prospectively evaluated frequency- (spectral analysis), geometric-, and time-domain indexes of HRV in normal term infants. Ninety-six asymptomatic infants who were <72 hours old were studied. Frequency-domain parameters (power in the high, low, very low, ultra low, and total frequency domains), a geometric parameter (HRV triangular index), and time-domain parameters (SDNN, SDANN, SDNNi, r-MSSD, s-NN50) are reported as means +/- SD, medians, and 5th and 95th percentiles to establish the normative values for newborns. A high degree of correlation (r > or = 0.85, p <0.0001) was noted among the 3 vagal tone dependent parameters, such as high-frequency power (frequency domain), r-MSSD, and s-NN50 (time domain). Our study supports the use of vagal dependent time-domain parameters like r-MSSD and sNN50 as surrogates for high-frequency power in newborns. Because the data are reported as means +/- SD, medians, and 5th and 95th percentiles, their use facilitates the study of parasympathetic and sympathetic activity in comparable populations.     

Heart rate variability in patients with atrial septal defect and healthy children

ObjectiveHeart rate variability (HRV) measures are altered in various cardiac and non-cardiac situations in children. The autonomic nervous system is assumed to have a role in the pathophysiology of atrial septal defect (ASD). In this study, we evaluated the autonomic system by measuring HRV in children with ASD.MethodsTwenty-eight patients with ASD and 32 healthy children (mean ages: 6.6 ± 2.1 years and 6.4 ± 2.2 years, respectively) were enrolled in the study. Twenty-four-hour ambulatory electrocardiographic recordings were obtained and the seven time-domain (SDNN, SDANN, rMSSD, SD, SDNN index, PNN50, and mean RR) and four frequency-domain (VLF, LF, HF, and LF/HF ratio) indices of HRV were analyzed.ResultsA significant decrease in calculated HRV variables was observed in children with ASD as compared to controls. The HRV alteration was found in both time-domain and frequency-domain parameters.ConclusionsOur results indicate that HRV is decreased in children with ASD, which implies parasympathetic withdrawal and sympathetic predominance.     

Heart rate recovery is associated with obesity traits and related cardiometabolic risk factors in children and adolescents

Background and aimsIncreased vagal activity is associated with obesity and metabolic risk in children and adolescents. The aim of the present cross-sectional study was to examine the association of parasympathetic function, as assessed by heart rate recovery (HRR) from a maximal exercise cycle-ergometer test, with obesity traits and related cardiometabolic risk factors in Spanish children and adolescents.Methods and resultsA sample of 437 Spanish 9-year-old-children and 235 15-year-old-adolescents participated in the study. The variables measured were anthropometric characteristics (height, body mass and waist circumference) and physical activity using the Actigraph accelerometer. Additional measured outcomes included fasting insulin, triglycerides, high-density lipoprotein cholesterol (HDLc) and blood pressure. A metabolic risk score was computed as the mean of the standardised outcomes scores. The HRR was calculated as the difference between peak heart rate and heart rate 1, 3 and 5 min after cessation of the maximal ergometer test. Diastolic blood pressure was associated with all the HRR parameters in 9-year-old-girls. In 9-year-old-boys, the 3-min HRR was inversely associated with systolic blood pressure (p < 0.05) and Homeostasis Model Assessment (HOMA) (p < 0.05). Five minute HRR was inversely associated with waist circumference (p < 0.05), sum of five skinfolds (p < 0.01) and HOMA (p = 0.004). There were no significant associations in adolescents. In 9-year-old-girls, the adjusted 5-min HRR showed significant differences between quartile 2 and 4 of metabolic risk (p = 0.011). In all samples, the adjusted HRR (1-, 3- and 5-min HRR) did not show significant differences across quartiles.ConclusionHRR was inversely associated with obesity traits and related cardiometabolic risk factors mainly in healthy boys.     

Heart rate recovery after exercise is related to the insulin resistance syndrome and heart rate variability in elderly men

Objective We investigated the associations between heart rate recovery after exercise (as a suggested measure of vagal activity), heart rate variability, and measurements of the insulin resistance syndrome. Material and Methods Seventy men aged 70 years were examined with a symptom-limited bicycle exercise test, a 24-hour heart rate variability test, and different measurements of different components of the insulin resistance syndrome. Results Heart rate recovery after exercise (mean ± SD 20 ± 9 beats during the first minute) was related to both the SD of the R-R interval and the low frequency power at the heart rate variability analyses (r = 0.39, P < .002 for both). Furthermore, heart rate recovery after exercise was related to insulin sensitivity at the hyperinsulinemic eugleucemic clamp (r = 0.28, P < .03), and to high-density lipoprotein cholesterol and exercise capacity, and inversely to obesity and insulin and glucose levels 2 hours after an oral glucose load (P < .05 for all). Heart rate recovery after exercise was not related to left ventricular mass measured by means of echocardiography or to the number of ventricular premature complexes at a 24-hour Holter recording. Conclusion Heart rate recovery 1 minute after exercise was related to measurements of 24-hour heart rate variability. Furthermore, heart rate recovery after exercise was related to several of the major components of the insulin resistance syndrome, thereby establishing a link between this syndrome and cardiac autonomic nervous activity. (Am Heart J 2002;144:666-72.)     

Heart rate variability in atrial fibrillation related to left atrial size

The purpose of this investigation was to determine whether heart rate variability (HRV) in atrial fibrillation (AF) can be related to any echocardiographic-derived measurements of cardiac dimensions or function. AF is characterized by marked HRV. Although HRV in normal sinus rhythm has been studied and shown to have important clinical implications, there have been relatively few published reports dealing with the phenomenon in AF. This study examines HRV in AF taking into account the influence of heart rate. HRV measurements were obtained in 38 patients with persistent AF who had undergone 24-hour ambulatory electrocardiographic monitoring. Taking into account a strong heart rate dependence of the HRV measurements, regressions were calculated. The relations were then re-examined using the differences (diff) in HRV from the expected for the average RR intervals. No significant correlations were found between unadjusted HRV measurements and any clinical features or echocardiographic variables. However, taking into account heart rate relations, with negative HRVdiff signifying less HRV than expected, reduced HRV correlated with increasing left atrial and left ventricular dimensions. On multivariate regression analysis, left atrial dimension emerged as an independent determinant of HRV. Also, HRV was greater in patients with lone AF than in those with cardiac disorders. HRV in AF is highly rate dependent. Unless this influence is taken into account, important relations may be obscured. When HRVdiff are related to echocardiographic measurements, increasing left atrial dimensions correlate with less HRV.     

Effects of gender and altitude on short-term heart rate variability in children.

OBJECTIVE: We aimed to study short-term heart rate variability (HRV) in 113 apparently healthy children permanent residents of moderate altitudes, the effects of gender and altitude. METHODS: Children were assigned into 3 groups according with altitude of residence: Group 1--1650 m/a/s/l (n=38), Group 2--1740 m/a/s/l (n=36) and Group 3--2030 m/a/s/l (n=39). All children underwent short-term electrocardiographic recordings with spectral analysis of HRV at rest and during standing. Statistical analysis was performed using multivariate ANOVA analysis. RESULTS: Heart rate variability analysis showed significant increase in SDNN, high frequency and total powers in parallel with increase of the altitude of residence (p<0.0001, p<0.03 and p<0.01, respectively). The magnitude of the HRV response to posture did not differ between groups except index of sympathetic modulation, LFNU, which rose to a significantly lesser degree (F=3.45, p<0.03) in Group 3, as compared with Group 1 and 2. Girls had lower HRV as compared with boys. CONCLUSION: Thus, in apparently healthy children, residents of moderate altitudes, increase in altitude levels is accompanied by higher overall variability and parasympathetic modulation of the sinus node and lower sympathetic response to posture. Heart rate variability in children, residents of moderate altitudes is also dependent of gender, resembling similar relationship in inhabitants of sea level.     

Heart rate variability in physically active individuals: reliability and gender characteristics

Purpose

To evaluate the reliability of short-term recordings (five minutes) of heart rate variability (HRV) and the association between HRV and gender.

Methods

HRV time- and frequency-domain parameters were calculated in 44 physically active students (21 males and 23 females) over four consecutive days. A Suunto t6 heart rate monitor was used to obtain inter-beat intervals (IBIs) that were then transferred to Kubios HRV analysis software. The relative reliability [intra-class correlation (ICC)] and absolute reliability, [typical error of measurement (TEM) and typical error of measurement as a percentage (TEM%)] of the HRV parameters were then calculated for day 2 versus day 3 and day 3 versus day 4, with day 1 being a familiarisation day. The following HRV parameters were calculated: (1) time domain: resting heart rate (RHR), R–R intervals (IBI), standard deviation of normal-to-normal intervals (SDNN), root mean square differences of the standard deviation (RMSSD), percentage of beats that changed more than 50 ms from the previous beat (pNN50); and (2) frequency domain: low-frequency normalised units (LFnu), high-frequency normalised units (HFnu), low-frequency to high-frequency ratio in normalised units (LF/HFnu). An analysis of variance (ANOVA) with Tukey post-hoc testing was performed to compare HRV parameters in males and females. Significance was set at p ≤ 0.05.

Results

The ICCs for both relationship 1 and 2 indicated primarily good to excellent (> 0.8) relative reliability. The lowest value was found in the LF/HFnu ratio (ICC = 0.36) for males. Absolute reliability was low with TEM% greater than 10% for all HRV parameters, except IBIs. Females demonstrated better relative (higher ICCs) and absolute reliability (lower TEM and TEM%) compared to males for the frequency domain. The relative and absolute reliability for the time domains were similar except for SDNN where the absolute reliability was higher in males. ANOVA illustrated significant gender differences for the LF/HFnu ratio (41% higher in males, p = 0.003), HFnu (12% higher in females, p = 0.02) and IBI (21% higher in females, p < 0.0001).

Conclusions

Short-term recordings of HRV over three consecutive days demonstrated a high relative reliability. However, a low absolute reliability indicated large day-to-day random variation in HRV, which would make the detection of intervention effects using HRV difficult in individual participants. Females were shown to have a higher parasympathetic modulation of HRV, which may indicate an underlying cardioprotective mechanism in females compared to males.     

Heart rate variability in healthy children and in those with congenital heart disease both before and after operation

There are no reports of standard measures of heart rate variability (HRV) in pediatric patients with heart disease. Time domain (standard deviation of all normal RR intervals [SDNN], standard deviation of all 5-minute mean RR intervals, average standard deviation of all 5-minute RR intervals, and frequency domain (total, low- [LF], and high-frequency [HF] power) measures of HRV were (1) obtained in 45 healthy children, (2) compared between 36 children with congenital heart disease and age-matched controls, (3) compared before and after surgery, and (4) compared between age-matched postoperative patients staying <7 days (group I, n = 16) and those staying longer (group II, n = 16). In healthy children, SDNN increased rapidly during infancy and more gradually thereafter, while the LH/HF ratio decreased until preschool age, with a later increase into adolescence. Compared with controls, preoperative patients had decreased total (53 ± 55 vs 84 ± 75 beats/min²/Hz, p = 0.01) and HF (12 ± 14 vs 29 ± 46 beats/min²/Hz, p = 0.03) power despite having similar heart rates. In the immediate postoperative period, all measures of HRV were decreased from preoperative values. Groups I and II did not differ in mean RR interval or HRV preoperatively; however, postoperatively, HRV was decreased in group II when compared with group I (SDNN 53 ± 17 vs 40 ± 14 ms, p = 0.01), although the mean RR interval remained comparable (499 ± 81 vs 481 ± 62 ms, p = 0.3). It is concluded that (1) there are significant age-related changes in HRV in healthy children, (2) preoperatively, children with congenital heart disease have reduced total and HF power when compared with healthy controls, (3) HRV is further reduced postoperatively in all patients, and (4) prolonged postoperative hospitalization is associated with a greater reduction in HRV.     

Heart rate variability and circulating catecholamine concentrations during steady state exercise in healthy volunteers.

OBJECTIVES--To assess whether exercise induced suppression of heart rate variability in the low frequency domain (0.06-0.15 Hz) is related to the increase in circulating catecholamine concentrations. DESIGN--Randomised crossover trial of three exercise tests characterised by different workloads. Pharmacological simulation of exercise-induced changes in vagal and sympathetic activity. PARTICIPANTS--Six healthy men with a mean age of 31.2 (SD 3.0) years. INTERVENTIONS--Three different workloads of steady state cycling ergometry: control state without cycling, cycling at a target heart rate of 100 beats/min, and cycling at a target heart rate of 150 beats/min. Intravenous infusion of atropine (target heart rate 100 beats/min) followed by the additional infusion of adrenaline and noradrenaline. MAIN OUTCOME MEASURES--Fast Fourier analysis of heart rate variability; blood pressure; and venous plasma concentrations of lactate, adrenaline, and noradrenaline. RESULTS--During the control exercise period there were no changes in the assessed variables compared with the preceding resting period. During exercise at a heart rate of 100 beats/min systolic blood pressure increased and heart rate variability decreased. During exercise at a heart rate of 150 beats/min systolic blood pressure and lactate, adrenaline, and noradrenaline concentrations increased. In addition, low frequency (LF) was lower than during exercise at 100 beats/min, high frequency (HF 0.15-0.80 Hz) resembled that during exercise at 100 beats/min, and diastolic blood pressure was reduced. Infusion of atropine caused no changes in blood pressure or plasma concentrations of lactate, adrenaline, and noradrenaline and decreased heart rate variability. The additional infusion of adrenaline and noradrenaline completely suppressed heart rate variability and increased blood pressure. CONCLUSIONS--The reduction in LF and HF during exercise at a heart rate of 100 beats/min, which is not characterised by increased plasma catecholamine concentrations, and during atropine infusion suggests that heart rate variability in the supine state is largely influenced by vagal activity. The additional reduction in LF during exercise at 150 beats/min and during catecholamine infusion may reflect a negative feedback of circulating catecholamines on the sympathetic control of heart rate.     

Heart rate variability and heart rate in healthy volunteers. Is the female autonomic nervous system cardioprotective?

Aims Heart rate variability has been proposed as an indicator ofcardiovascular health. Since women have a lower cardiovascularrisk, we hypothesized that there are gender differences in autonomicmodulation. Methods and Results In 276 healthy subjects (135 women, 141 men) between 18 and71 years of age, 24h heart rate and heart rate variability weredetermined. All heart rate variability parameters, except forpNN50 and high frequency power, were higher in men. After adjustmentfor heart rate, we obtained gender differences for: the standarddeviation (P=0·049), the standard deviation of the 5minaverage (P=0·047), low frequency power (absolute values,P=0·002;normalized units,P<0·001) and ratio low frequency/highfrequency (P<0·001). There were no significant genderdifferences in heart rate variability parameters denoting vagalmodulation. Gender differences were confined to age categoriesof less than 40 years of age. The majority of heart rate variabilityparameters decreased with age. Only in men, was a higher bodymass index associated with a higher heart rate and with lowerheart rate variability parameters (P<0·001). Conclusion Cardiac autonomic modulation as determined by heart rate variability,is significantly lower in healthy women compared to healthymen. We hypothesize that this apparently paradoxical findingmay be explained by lower sympathetic activity (low frequencypower) in women. This may provide protection against arrhythmiasand against the development of coronary heart disease.