Circadian rhythm of heart rate and heart rate variability

BACKGROUND—Measurements of heart rate variability (HRV) are increasingly used as markers of cardiac autonomic activity.AIM—To examine circadian variation in heart rate and HRV in children.SUBJECTS—A total of 57 healthy infants and children, aged 2 months to 15 years, underwent ambulatory 24 hour Holter recording. Monitoring was also performed on five teenagers with diabetes mellitus and subclinical vagal neuropathy in order to identify the origin of the circadian variation in HRV.METHODS—The following variables were determined hourly: mean RR interval, four time domain (SDNN, SDNNi, rMSSD, and pNN50) and four frequency domain indices (very low, low and high frequency indices, low to high frequency ratio). A chronobiological analysis was made by cosinor method for each variable.RESULTS—A significant circadian variation in heart rate and HRV was present from late infancy or early childhood, characterised by a rise during sleep, except for the low to high frequency ratio that increased during daytime. The appearance of these circadian rhythms was associated with sleep maturation. Time of peak variability did not depend on age. Circadian variation was normal in patients with diabetes mellitus.CONCLUSION—We have identified a circadian rhythm of heart rate and HRV in infants and children. Our data confirm a progressive maturation of the autonomic nervous system and support the hypothesis that the organisation of sleep, associated with sympathetic withdrawal, is responsible for these rhythms.     

Circadian rhythm of heart rate and heart rate variability.

BACKGROUND: Measurements of heart rate variability (HRV) are increasingly used as markers of cardiac autonomic activity. AIM: To examine circadian variation in heart rate and HRV in children. SUBJECTS: A total of 57 healthy infants and children, aged 2 months to 15 years, underwent ambulatory 24 hour Holter recording. Monitoring was also performed on five teenagers with diabetes mellitus and subclinical vagal neuropathy in order to identify the origin of the circadian variation in HRV. METHODS: The following variables were determined hourly: mean RR interval, four time domain (SDNN, SDNNi, rMSSD, and pNN50) and four frequency domain indices (very low, low and high frequency indices, low to high frequency ratio). A chronobiological analysis was made by cosinor method for each variable. RESULTS: A significant circadian variation in heart rate and HRV was present from late infancy or early childhood, characterised by a rise during sleep, except for the low to high frequency ratio that increased during daytime. The appearance of these circadian rhythms was associated with sleep maturation. Time of peak variability did not depend on age. Circadian variation was normal in patients with diabetes mellitus. CONCLUSION: We have identified a circadian rhythm of heart rate and HRV in infants and children. Our data confirm a progressive maturation of the autonomic nervous system and support the hypothesis that the organisation of sleep, associated with sympathetic withdrawal, is responsible for these rhythms.     

Does fetal heart rate predict subsequent heart rate in childhood?

An investigation to determine whether there is any relationship between extremes of fetal heart rate during labour and subsequent heart rate at the age of 10 was carried out using data from the 1970 cohort of British Births. In 11,000 nationally representative children it was found that low fetal heart rate (below 120 beats/min) was associated with a heart rate at age 10 which was significantly lower than in those children whose fetal heart rate had remained between 120 and 160 beats/min (P less than 0.01). This relationship could not be explained by fetal asphyxiation, maternal antenatal hypotension or the method of pain relief during labour. There was no equivalent relationship with high fetal heart rate during labour. This could imply that some fetuses with low heart rates are not exhibiting fetal distress but have an inherent tendency to relatively slow heart rates.     

正常儿童动态心电图窦性心率及心率变异分析

目的探讨正常儿童心率及心率变异性(HRV)特点。方法对804例正常儿童进行24h全程动态心电图检查,分析心率及HRV。结果不同年龄儿童窦性心率范围不同,年龄越小心率越快;儿童不同性别间HRV中24h内全部正常心动周期的标准差(SDNN)、24h内每5minNN间期标准差的平均值(SDNNindex)、NN50占所有N-N间期个数的百分数(PNN50)、极低频率(VLF)、低频(LF)差异有显著性;儿童不同年龄组间24h内5min节段平均心动周期的标准差(SDANN)、VLF、LF、全程相邻NN间期之间的均方根值(rMSSD)差异有显著性;儿童组与成人正常参考值中SDNN、SDANN、rMSSD差异有显著性,rMSSD儿童组中明显高于成人组。结论HRV是一种反映自主神经活性及其平衡的能定量、可重复的非侵入性的检测方法,是自主神经系统与心血管系统相互制约的结果。不同年龄、不同性别间儿童HRV存在显著差异;儿童组与成人参考值存在显著差异,尤其rMSSD儿童明显高于成人,提示儿童的自主神经功能较成人活跃,而随着年龄增长自主神经功能减退,尤其是迷走神经的紧张抑制功能明显减退。     

Heart rate turbulence in children--age and heart rate relationships

Heart rate turbulence (HRT) is a chronotropic response of the sinus heart rhythm to ventricular premature beat (VPB). Children show decreasing heart rate together with the maturation of the autonomic nervous system. The aim of the research was to assess the relationship between HRT parameters, age, and heart rate and time domain heart rate variability (HRV) parameters in healthy children. Twenty-four-hour ECG Holter recording was performed on 398 healthy children. The mean RR interval preceding VPB, number of VPBs, and HRT parameters-turbulence onset (TO) and turbulence slope (TS)-were determined. We observed significant correlation among TS and mean RR and age. Children with prepubertal status have lower values of TS compared with those during puberty. According to given quartiles, upper for TO was > or =-0.8%, lower for TS was < or =4.56 ms/RR, 13 patients (3%) obtained abnormal both TO and TS. The correlations between HRT and HRV parameters were observed among the youngest children. Age and heart rate preceding VPB have no effect on HRT onset in children, whereas HRT slope is highly dependent on these variables. Our results support hypothesis that in older children HRT is dependent on autonomic tone and also determined by other intrinsic modulators.     

心率变异性、心率减速力与静脉注射免疫球蛋白无反应川崎病的相关性

目的:探讨川崎病(KD)患儿急性期心率变异性(HRV)、心率减速力(DC)与静脉注射免疫球蛋白(IVIG)无反应KD的关系。方法:纳入2015年8月至2019年5月成都市妇女儿童中心医院收治的临床资料完整的KD患儿679例进行前瞻性队列研究,选择同期进行健康体检儿童150例为健康对照组。根据接受初始IVIG治疗14 d...     

心肌炎患儿与正常儿童心率及心率变异性比较分析

目的 研究不同年龄心肌炎患儿的心率及心率变异性(HRV)改变的特点和相关性.方法 对120例心肌炎患儿进行24 h全程动态心电图检查,与804例正常儿童的心率及HRV进行比较分析.结果 7岁以下患儿最慢心率较正常增快,最快心率比较变化无差异,7～18岁患儿心率监测指标均异常;3～7岁心肌炎患儿与正常儿童比较每5分钟R-R间期平均值的标准差(SDANN)无变化,各组其他HRV指标均降低.结论 心肌炎患儿的HRV普遍降低,提示心脏自主神经系统的总体功能受损,以迷走神经张力降低为主,交感神经张力相对增强.     

Fetal heart rate in early pregnancy

Heart rates were measured by transvaginal sonography twice weekly in ten first trimester fetuses in women who conceived after in-vitro fertilization (IVF) or zygote intra-fallopian transfer (ZIFT). From week 6 to week 9 of menstrual age a rapid increase of the mean heart rate was observed from 113 to 167 beats per min, followed by a slow decrease to 156 beats per min. A close correlation between crown-rump length and heart rate was established.     

学龄期肥胖儿童胰岛素抵抗与心率变异性及心率减速力的相关性

目的探讨学龄期肥胖儿童胰岛素抵抗(IR)与心率变异性(HRV)、心率减速力(DC)及心率加速力(AC)之间的关系。方法选取学龄期6～10岁肥胖儿童83例,根据空腹血糖及空腹胰岛素值计算胰岛素抵抗指数(IRI),再根据IRI值将实验对象分为IR组45例和非IR组38例。在检测空腹血糖及空腹胰岛素同日行24小时动态心电图检查,计算出DC、AC、HRV各指标。比较IR组与非IR组DC、AC、HRV各指标,并进行相关性分析。结果 IR组DC、正常RR间期标准差(SDNN)、5分钟均值标准差(SDANN)、高频功率(HF)均低于非IR组,AC高于非IR组,差异均有统计学意义(P0.05)。肥胖儿童的IRI与DC、SDNN、SDANN、相邻RR间期差值的均方根(RMSSD)、低频功率(LF)、HF均呈显著负相关(r=-0.475～-0.249,P0.05),与AC呈显著正相关(r=0.488,P0.01)。结论 IR较非IR肥胖儿童的自主神经功能损伤严重,主要表现为迷走神经张力降低,且IRI越高,迷走神经张力越低。     

Sound and vibration: effects on infants' heart rate and heart rate variability during neonatal transport

Aim: To measure the effect of sound and whole‐body vibration on infants’ heart rate and heart rate variability during ground and air ambulance transport. Methods: Sixteen infants were transported by air ambulance with ground ambulance transport to and from the airports. Whole‐body vibration and sound levels were recorded and heart parameters were obtained by ECG signal. Results: Sound and whole‐body vibration levels exceeded the recommended limits. Mean whole‐body vibration and sound levels were 0.19 m/s² and 73 dBA, respectively. Higher whole‐body vibration was associated with a lower heart rate (p < 0.05), and higher sound level was linked to a higher heart rate (p = 0.05). The heart rate variability was significantly higher at the end of the transport than at the beginning (p < 0.01). Poorer physiological status was associated with lower heart rate variability (p < 0.001) and a lower heart rate (p < 0.01). Infants wearing earmuffs had a lower heart rate (p < 0.05). Conclusions: Sound and whole‐body vibration during neonatal transport exceed recommended levels for adults, and sound seem to have a more stressful effect on the infant than vibrations. Infants should wear earmuffs during neonatal transport because of the stress‐reducing effect.     

学龄前儿童病毒性心肌炎心率变异性与心率减速力分析

目的探讨病毒性心肌炎患儿心率变异性(HRV)与心率减速力(DC)各项指标变化的临床意义。方法对56例病毒性心肌炎患儿与58例正常对照儿童进行24 h动态心电图检查,应用美国DMS公司的动态心电分析系统软件,对HRV及DC各项参数进行分析对比;并分析DC与其他各项指标之间的相关性。结果与正常对照儿童比较,病毒性心肌炎患儿时域分析的各项参数包括正常窦性RR间期的标准差(SDNN)、每5 min时段内平均正常窦性RR间期的标准差(SDANN)、全程RR间期差的均方根(RMSSD)及频域分析的低频功率(LF)的差异均无统计学意义(P>0.05),而高频功率(HF)显著减低,差异有统计学意义(P<0.05),且DC显著减低,差异有统计学意义(P<0.01)。相关性分析中,DC与SDNN、LF、HF均成正相关,其中与HF的相关性最强(r=0.51,P<0.01)。结论病毒性心肌炎患儿存在迷走神经功能受损,心率变异性中的HF与DC反映迷走神经功能的指标均显著降低,且两者具有很大相关性。     

Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability

Background

Previous studies using ultrasound technology showed that fetal heart rate (HR) may be responsive to maternal aerobic exercise. Although it is recognized that cardiac autonomic control may be influenced by the intrauterine environment, little is known about how maternal exercise affects fetal heart development.

Aims

This study tested the hypothesis that regular maternal exercise throughout gestation influences fetal cardiac autonomic control of HR and heart rate variability (HRV) when compared to fetuses of non-exercising women.

Study design

Magnetocardiograms (MCGs) were recorded using a dedicated fetal biomagnetometer at 28, 32 and 36 weeks gestational age (GA) from 26 regularly exercising (> 30 min of aerobic exercise, 3× per week) and 35 healthy, non-exercising pregnant women. Fetal MCG was isolated and normal R-peaks were marked to derive fetal HR and HRV in the time and frequency domains. We applied a mixed-effects model to investigate the effects of exercise, GA and fetal activity state.

Results

At 36 weeks GA, during the active fetal state, fetal HR was significantly lower in the exercise group (p = < 0.0006). Post-hoc comparisons showed significantly increased HRV in the exercise group during the active fetal state at 36 weeks GA for both time and frequency domain measures.

Conclusion

These results indicate that regular maternal exercise throughout gestation results in significantly lower fetal HR and increased HRV.     

Factors affecting heart rate variability and heart rate responses to tilting in infants aged 1 and 3 months

Heart rate variability (HRV) and heart rate (HR) responses following a 60 degree head-up tilt were measured in 60 infants at 1 and 3 mo of age to investigate the effects on these of age, sleep state, sleep position, and mother's smoking status. HRV was determined from Poincaré plots of 500 sequential RR intervals to measure overall variability derived from the SDRR of this plot, and instantaneous variability derived from the SDdeltaRR. HR responses to the tilt were measured as changes in RR interval length from rest to immediately following the tilt and again once a stable pattern was reached. SDRR and SDdeltaRR increased 20 and 40%, respectively, with age (p < 0.0001), SDRR was higher in active sleep (AS) than quiet sleep (QS, +72%, p < 0.0001) but both measures of variability (SDRR and SDdeltaRR) were lower in the prone position compared with supine (-18%, p < 0.0001). However, several findings were dependent on the basal RR interval, thus the age effect disappeared once RR interval was taken into account, sleep state remained an important factor and the lower variability when prone now became a difference of -3% (p = 0.034). The tilt generally provoked a reflex tachycardia followed by a bradycardia and settling to a stable HR level below, at, or above baseline within 30 s. The more unusual responses were no HR change, sustained tachycardia or sustained bradycardia (15% of total). These were more likely to occur in younger infants (p = 0.008) and in AS (p < 0.0001). No changes were seen in any of the cardiac indices related to maternal smoking status. The findings confirm several reports indicating that prone sleeping damps some physiologic responses. The data emphasize the need to consider basal heart rate, and sleep position as well as sleep state in autonomic function testing during infant sleep.     

甲状腺功能亢进症儿童的甲状腺激素与心率减速力及心率变异性的相关性

目的 对甲状腺功能亢进症（简称“甲亢”）儿童的心率减速力（DC）、心率加速力（AC）、心率变异性（HRV）进行分析,并探讨甲亢儿童的血清甲状腺激素水平与DC、AC及HRV的关系。方法 选取甲亢儿童47例,另选取50例健康儿童为对照组,对所有受试者行24 h动态心电图检查,将甲亢组与对照组的DC、AC、心率（HR）及HRV各指标[RR间期总体标准差（SDNN）、RR间期平均值的标准差（SDANN）、相邻RR间期差值的均方根（RMSSD）、低频功率（LF）、高频功率（HF）]进行比较,并将甲亢儿童的甲状腺激素指标[游离三碘甲状腺原氨酸（FT3）、游离甲状腺素（FT4）]与DC、AC及HRV各指标进行相关性分析。结果 甲亢组的DC、SDNN、SDANN、RMSSD、LF、HF均低于对照组;AC和HR均高于对照组（P < 0.05）。甲亢儿童的血清FT3、FT4与DC、SDNN、SDANN、RMSSD、LF、HF均呈负相关（P < 0.05）;与AC和HR呈正相关（P < 0.05）。结论 甲亢儿童的心脏自主神经功能受损,表现为迷走神经张力降低。血清甲状腺激素水平越高,迷走神经张力越低,提示发生心血管疾病的危险性越大。     

Monitoring heart rate in the delivery room

Resuscitation algorithms and guidelines highlight the importance of heart rate (HR) in determining interventions and assessing their effect. However, the actual HR values used are historical based upon normal physiology, and HR at birth may be affected by mode of delivery and timing of cord clamping as well as respiratory status and condition at delivery. Furthermore, the most accurate and effective ways to assess and monitor HR in the newborn infant are only now becoming established. This article examines the importance of HR values and the most widely used methods of estimation as well as some newer modalities which are being developed.