Differences In Heart Rate Variability Measures Research Articles

Cardiac autonomic dysfunction in adult congenital heart disease

PurposeDue to recent advances in diagnosis and treatment, the number of adults with congenital heart disease (ACHD) has substantially increased. This achievement is mitigated by rhythm disorders. Here, we sought to determine alterations in heart rate variability (HRV) and their prognostic value in ACHD.MethodsNinety seven ACHD patients (39.2 ± 14.1 years, 51.5% female) and 19 controls (39.7 ± 15.0 years, 47.4% female) underwent 24-h Holter monitoring.ResultsAs compared to controls, ACHD patients offered a significantly higher burden of premature ventricular contractions (p = 0.02) and decreased HRV indices (natural logarithmic transformation of very low frequency (lnVLF): 7.46 ± 0.76 ms2 vs. 7.91 ± 0.92ms2, p = 0.03; natural logarithmic transformation of low frequency (lnLF): 6.39 ± 0.95ms2 vs. 7.01 ± 1.07ms2, p = 0.01; natural logarithmic transformation of the ratio of low to high frequency spectra (lnLF/HF): 0.81 ± 0.74 vs. 1.17 ± 0.51, p = 0.04). No differences in HRV measures were observed across ACHD lesion groups. NT-proBNP levels were significantly related to both time and frequency domain indices (natural logarithmic transformation of the standard deviation of NN intervals (lnSDNN): Spearman´s rho = -0.32, p = 0.001; natural logarithmic transformation of the standard deviation of the average NN intervals for each 5-min segment of a 24-h Holter monitoring (lnSDANN): Spearman´s rho: -0.33, p = 0.001; natural logarithmic transformation of the total power (lnTP): Spearman´s rho: -0.25, p = 0.01; lnVLF: Spearman´s rho: -0.33, p = 0.001; lnLF: Spearman´s rho: -0.35, p < 0.001; lnLF/HF: Spearman´s rho: -0.34, p = 0.001).After a mean follow-up of 3.9 ± 0.7 years, 8 patients died and 3 patients survived sudden cardiac death (SCD). Several HRV parameters were significantly higher in event-free ACHD patients than in those who died or survived SCD (natural logarithmic transformation of the average of the standard deviations of NN intervals for each 5-min segment of a 24-h Holter monitoring (lnASDNN): p = 0.04; lnPNN30: p = 0.04; lnVFL: p = 0.03; lnLF: p < 0.01). On univariate Cox regression analysis, the time domain indices lnSDNN, lnASDNN and lnPNN30, as well as the frequency domain parameters lnTP, lnVLF and lnLF were associated with death and survived cardiac arrest.ConclusionACHD is accompanied by HRV impairment that carries prognostic implications on ACHD mortality and survived SCD.

Differences between Elite Male and Female Badminton Athletes Regarding Heart Rate Variability, Arterial Stiffness, and Aerobic Capacity.

Cardiovascular health and aerobic capacity play crucial roles in determining the performance of athletes in the highly competitive sport of badminton. Few studies have directly compared heart rate variability (HRV), arterial stiffness, and aerobic capacity between male and female athletes, especially among badminton athletes. This study investigated sex differences in HRV, arterial stiffness, and aerobic capacity in badminton athletes. Elite badminton athletes were recruited and divided into male (n = 20, 21.0 ± 1.8 years old) and female (n = 16, 21.2 ± 2.3 years old) groups. Both groups performed an incremental treadmill running test for the evaluation of maximal oxygen consumption (O2max), anaerobic threshold, and time to exhaustion. They started exercising at a treadmill speed of 2.7 km/h and an inclination of 10% gradient for 3 min, and the speed and inclination were gradually increased every 3 min until they were exhausted or fatigued volitionally. HRV was examined using the Polar heart rate monitor over a period of 5 min at rest in the supine position. Subsequently, the index of arterial stiffness was examined under the same condition. Our results revealed significant differences between the male and female athletes in O2max (men: 60.38 ± 8.98 mL/kg/min, women: 48.13 ± 7.72 mL/kg/min, p < 0.05), anaerobic threshold (men: 41.50 ± 7.26 mL/kg/min, women: 32.51 ± 6.19 mL/kg/min, p < 0.05), time to exhaustion (men: 902.15 ± 120.15 s, women: 780.56 ± 67.63 s, p < 0.05), systolic blood pressure (men: 125.27 ± 7.76 mmHg, women: 107.16 ± 11.09 mmHg, p < 0.05), and arterial stiffness index (men: 63.56 ± 12.55, women: 53.83 ± 8.03, p < 0.05). However, no significant differences in HRV measures were observed between the two groups. These findings suggested that the male badminton athletes demonstrated significantly higher aerobic capacity than did the female athletes, but there were no significant differences in HRV measures. The female athletes exhibited superior arterial function, compared with their male counterparts.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BackgroundNeonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.ObjectivesTo describe the different types...

Sex Differences in Time-Domain and Frequency-Domain Heart Rate Variability Measures of Fatigued Drivers.

The effects of fatigue on a driver’s autonomic nervous system (ANS) were investigated through heart rate variability (HRV) measures considering the difference of sex. Electrocardiogram (ECG) data from 18 drivers were recorded during a simulator-based driving experiment. Thirteen short-term HRV measures were extracted through time-domain and frequency-domain methods. First, differences in HRV measures related to mental state (alert or fatigued) were analyzed in all subjects. Then, sex-specific changes between alert and fatigued states were investigated. Finally, sex differences between alert and fatigued states were compared. For all subjects, ten measures showed significant differences (Mann-Whitney U test, p < 0.01) between different mental states. In male and female drivers, eight and four measures, respectively, showed significant differences between different mental states. Six measures showed significant differences between males and females in an alert state, while ten measures showed significant sex differences in a fatigued state. In conclusion, fatigue impacts drivers’ ANS activity, and this impact differs by sex; more differences exist between male and female drivers’ ANS activity in a fatigued state than in an alert state.

Overnight heart rate variability and next day cortisol response during simulated on-call conditions

ObjectiveThis study had two specific objectives, 1) to investigate the impact of being on-call on overnight heart rate variability during sleep and; 2) to examine whether being on-call overnight impacted next-day salivary cortisol concentrations. MethodsData are reported from three within-subject laboratory studies (n = 24 in each study) that assessed varying on-call conditions. Healthy male participants (n = 72 total) completed a four-night laboratory protocol, comprising an adaptation night, a control night, and two counterbalanced on-call nights with varying on-call conditions. These on-call conditions were designed to determine the impact of, Study 1: the likelihood of receiving a call (definitely, maybe), Study 2: task stress (high-stress, low-stress), and Study 3: chance of missing the alarm (high-chance, low-chance), on measures of physiological stress. Overnight heart rate variability (HRV) (during sleep) was measured using two-lead electrocardiography, and time- and frequency-domain variables were analysed. Saliva samples were collected at 15-min time intervals from 0700-0800 h to determine cortisol awakening response outcomes and at four daily time points (0930 h, 1230 h, 1430 h, and 1730 h) to assess diurnal cortisol profiles. ResultsThere were few differences in HRV measures during sleep across all three studies. The only exception was in Study 1 where the standard deviation of the time interval between consecutive heartbeats and the root mean square of consecutive differences between heartbeats were lower across all sleep stages in the definitely condition, when compared to control. Across all three studies, being on-call overnight also had little impact on next-day cortisol awakening response (CAR), with the exception of Study 2 where the 1) CAR area under the curve with respect to increase was blunted in the high-stress condition, compared to the control and low-stress conditions and, 2) CAR reactivity was higher in low-stress condition, compared with the high-stress condition. In Study 1, diurnal cortisol area under the curve with respect to ground was lower in the on-call conditions (definitely and maybe) when compared to control. There were no differences in diurnal cortisol measures in Study 3. ConclusionThis is the first study to investigate how different aspects of being on-call affect physiological stress responses. Overall, relatively little differences in measures of overnight heart rate variability and next-day cortisol response were recorded in all three studies. Further research utilising real on-call work tasks, not just on-call expectations (as in the current study) will help determine the impact of on-call work on the physiological stress response.

Differences in development of neurocognitive functions in premature and healthy full-term infants

This study had two specific objectives, 1) to investigate the impact of being on-call on overnight heart rate variability during sleep and; 2) to examine whether being on-call overnight impacted next-day salivary cortisol concentrations.Data are reported from three within-subject laboratory studies (n = 24 in each study) that assessed varying on-call conditions. Healthy male participants (n = 72 total) completed a four-night laboratory protocol, comprising an adaptation night, a control night, and two counterbalanced on-call nights with varying on-call conditions. These on-call conditions were designed to determine the impact of, Study 1: the likelihood of receiving a call (definitely, maybe), Study 2: task stress (high-stress, low-stress), and Study 3: chance of missing the alarm (high-chance, low-chance), on measures of physiological stress. Overnight heart rate variability (HRV) (during sleep) was measured using two-lead electrocardiography, and time- and frequency-domain variables were analysed. Saliva samples were collected at 15-min time intervals from 0700-0800 h to determine cortisol awakening response outcomes and at four daily time points (0930 h, 1230 h, 1430 h, and 1730 h) to assess diurnal cortisol profiles.There were few differences in HRV measures during sleep across all three studies. The only exception was in Study 1 where the standard deviation of the time interval between consecutive heartbeats and the root mean square of consecutive differences between heartbeats were lower across all sleep stages in the definitely condition, when compared to control. Across all three studies, being on-call overnight also had little impact on next-day cortisol awakening response (CAR), with the exception of Study 2 where the 1) CAR area under the curve with respect to increase was blunted in the high-stress condition, compared to the control and low-stress conditions and, 2) CAR reactivity was higher in low-stress condition, compared with the high-stress condition. In Study 1, diurnal cortisol area under the curve with respect to ground was lower in the on-call conditions (definitely and maybe) when compared to control. There were no differences in diurnal cortisol measures in Study 3.This is the first study to investigate how different aspects of being on-call affect physiological stress responses. Overall, relatively little differences in measures of overnight heart rate variability and next-day cortisol response were recorded in all three studies. Further research utilising real on-call work tasks, not just on-call expectations (as in the current study) will help determine the impact of on-call work on the physiological stress response.

Effects of night-time on-call work on heart rate variability before bed and sleep quality in visiting nurses.

In Japan, many visiting nurses work carrying cell phones to respond to calls from users even at night (on-call work). The purpose of this study was to investigate whether on-call work affected heart rate variability (HRV) before bed and decreased sleep quality in visiting nurses even if their sleep was not interrupted due to actual calls. Thirty-one visiting nurses (mean age, 49.8 years; standard deviation, 6.3years) were asked to record their 2.5-min resting HRV before bed, and to undergo one-channel sleep electroencephalography (EEG) and subjective sleep evaluations upon waking (Oguri, Shirakawa, and Azumi Sleep Inventory) at home for 4-5 consecutive days, including both on-call and non-on-call days. Paired data sets of outcome measures, including HRV parameters, sleep macrostructure variables, and subjective sleep quality scores between on-call and non-on-call days were compared; the most recent measurements for each category were used for each subject. There were no differences in HRV measures and objective sleep EEG variables. A significant increase in "sleepiness on rising" and a decrease in "feeling refreshed" were observed on on-call days (P = 0.019 and 0.021, respectively), and younger subjects (≤ 51years old) demonstrated a significant reduction in "sleepiness on rising" (significant interaction effect, P = 0.029). Adverse effects of on-call work on sleep quality in most visiting nurses are thought to be subjective, and relatively young nurses tend to notice a decrease in sleep quality. On-call work itself does not appear to be a substantial stressor that could affect HRV and sleep structure.

Assessing Heart Rate Variability As a Surrogate Measure of Cardiac Autonomic Function in Chronic Traumatic Spinal Cord Injury.

Background: Although cardiac autonomic dysfunction is a contributing factor for cardiovascular disease development in individuals with a spinal cord injury (SCI), it remains poorly understood. Heart rate variability (HRV) analysis has the potential to non-invasively assess the cardiac autonomic nervous system. The study objectives are (a) to determine if there are differences in HRV measures across neurological level of impairment (NLI) and American Spinal Cord Injury Association Impairment Scale (AIS) subgroups, and (b) to determine if there is a relationship between HRV frequency measures (low frequency [LF] and high frequency [HF]) at rest. Methods: We conducted a secondary data analysis of a primary data set from a published cross-sectional study of electrocardiogram recordings of 56 subjects (44 men and 12 women, mean age ± SD = 46.75 ± 12.44 years) with a chronic traumatic SCI (C1-T12, AIS A-D, ≥2 years post injury). HRV was analyzed using time and frequency domain measures. Results: There were no significant HRV differences across NLI and AIS subgroups. The LF and HF indices were positively correlated in the entire sample (r = 0.708, p < .0001) and among impairment subgroups. Conclusion: No differences were observed in the HRV time and frequency measures when compared across NLI and AIS subgroups. The results were considered inconclusive, since possible explanations include inadequate sample size as well as other physiological considerations. A positive correlation was found between LF and HF when assessed at rest. The relationship between LF and HF may not necessarily represent a rebalanced autonomic nervous system, but it does question the utility of solely measuring LF:HF at rest in persons with chronic SCI.

Physical activity and heart rate variability measured simultaneously during waking hours

Heart rate (HR) variability (HRV) during ambulatory recordings may be affected by individual differences in daily physical activity (PA). However, the influence of various levels of PA on different measures of HRV is not exactly known. We examined the association between simultaneously measured HRV and objective PA data obtained with an accelerometer during waking hours among 45 healthy adults. Bouts of PA were identified from minute-by-minute accelerometer data as metabolic equivalent (METs) values and calculated as mean METs for 30 min. HRV was analyzed concurrently. Within-individual correlation analyses and sign tests were performed to study the relationships between various HRV indexes and PA. The mean PA time was 15:44 +/- 1:01 h, and the mean MET was 1.91 +/- 0.14. HR and sample entropy, but not the other measures of HRV, had a significant relationship with PA, as shown by both correlation analyses (r = 0.64, P = 0.021, and r = -0.55, P = 0.022, respectively) and sign tests (P < 0.0001 for both). Beat-to-beat R-R interval fluctuation expressed as SD1 also demonstrated a significant relation to PA according to the sign test (P = 0.037) and a trend of association according to the correlation analysis (r = -0.40, P = 0.129). The complexity measure of HRV, in addition to average HR and the short-term index of HRV (SD1), is significantly influenced by the level of PA during ambulatory conditions. Long-term HRV indexes remained relatively stable at various activity levels, making them the most robust indexes for the assessment of cardiac autonomic function during free-running ambulatory conditions.

The relationships among heart rate variability, inflammatory markers and depression in coronary heart disease patients

Studies show negative correlations between heart rate variability (HRV) and inflammatory markers. In cardiac patients, depression is related to both. We investigated links between short-term HRV and inflammatory markers in relation to depression in acute coronary syndrome (ACS) patients. We measured C-reactive protein (CRP), interleukin-6 (IL-6), depression symptoms (Beck Depression Inventory, BDI-II), and SDNN, high frequency (HF) and low frequency (LF) power at rest in 682 (553 men) patients approximately two months post-ACS. There were no differences in HRV measures between those with and without elevated depressions symptoms (BDI-II⩾14). However, all HRV measures were negatively and significantly associated with both inflammatory markers. Relationships were stronger in patients with BDI-II⩾14. Differences were significant for CRP and not explained by covariates (including age, sex, previous MI, left ventricular ejection fraction, coronary bypass surgery at index admission, diabetes, smoking, body mass index (BMI), fasting cholesterol, fasting glucose, angiotensin-converting-enzyme inhibitors, beta-blockers, statins, and antidepressants). HRV independently accounted for at least 4% of the variance in CRP in the depressed, more than any factor except BMI. Relationships between measures of inflammation and autonomic function are stronger among depressed than non-depressed cardiac patients. Interventions targeting regulation of both autonomic control and inflammation may be of particular importance.

Effect of n-3 fatty acids on heart rate variability and baroreflex sensitivity in middle-aged subjects

Background N-3 fatty acids may reduce the risk of sudden death by preventing life-threatening cardiac arrhythmias. Heart rate variability (HRV) and baroreflex sensitivity (BRS) reflect cardiac autonomic regulation; reduced values predict arrhythmic events and mortality. Effects of n-3 fatty acids on these risk indicators of arrhythmia have not been widely studied. We investigated the effect of supplemental intake of n-3 fatty acids on HRV and BRS in apparently healthy subjects aged 50 to 70 years. Methods After a run-in period of 4 weeks, 84 subjects were randomized to receive capsules with either 3.5 g of fish oil or placebo oil daily for 12 weeks. Before and after intervention, electrocardiograms and blood pressure were recorded for 10 minutes with standardized respiration of 15 breaths/min. The SD of the duration of all normal RR intervals (SDNN 10) and the root mean square successive differences (RMSSD 10) were calculated from the 10-minute recordings. We also computed low frequency power (LF) and high frequency power (HF). BRS was computed by integrating the spectral systolic blood pressure to interbeat-interval transfer function in the 0.05- to 0.15-Hz band. Results The different measures of HRV and BRS did not significantly improve with the intake of n-3 fatty acids. SDNN 10 decreased by 3.05 ms or 7.7% (95% CI, −8.91-2.82 ms), and BRS decreased by 0.92 ms/mm Hg or 0.1% (95% CI, −2.66-0.81 ms/mm Hg) in the fish oil group compared with the placebo group. Conclusions N-3 fatty acids have no effect on HRV from short-term recordings and BRS in apparently healthy subjects.

Fractal and periodic heart rate dynamics in fetal sheep: comparison of conventional and new measures based on fractal analysis.

The physiological significance of spectral and fractal components of spontaneous heart rate (HR) variability in the fetus remains unclear. To examine the relationship between circadian rhythms in different measures of HR variability, R-R interval time series obtained by fetal ECGs were recorded continuously over 24 h in five pregnant sheep at 116-125 days gestation. Conventional measures of short-term (STV) and long-term variability (LTV), low-frequency (LF; 0.025-0.15 cycles/beat) and high-frequency (HF; 0.2-0.5 cycles/beat) spectral powers, the LF-to-HF ratio, and fractal dimension values were calculated from 24-h ECG recordings and quantified every 60 min. STV, LTV, and LF and HF spectral powers were minimal during the day but increased significantly to their highest values at night. We found a significant positive correlation between these measures, whereas the cosinor method showed significant similarity between their circadian rhythm patterns. Fetal R-R intervals also exhibited fractal structures. Fetal HR variability had a fractal structure, which was similar between day and night. These results suggested that the circadian rhythms exhibited by STV and LTV during the day were mainly due to changes in frequency components rather than to fractal components of fetal HR fluctuation.

Heart Rate Variability in Patients with Neurocardiogenic Syncope or Presyncope

Background and Objectives:Neurocardiogenic syncope is believed to be caused by a transient imbalance of autonomic nervous system. Actually, there were significant differences in heart rate variability (HRV) indices during head-up tilt test between patients with neurocardiogenic syncope and normal controls. But there was no definite evidence for it during daily activity. So, we tried to evaluate HRV during daily activity with 24-hour ambu-latory electrocardiography monitoring. Materials and Methods:27 patients with neurocardiogenic syncope or presyncope (mean age 45±3) and 25 normal volunteers (mean age 47±2) comparable for age and sex underwent 24-hour ambulatory electrocardiography. Head-up tilt test was used to diagnose neurocardiogenic syncope or presyncope in patients group. HRV was analysed over the whole 24 hours, using time and frequency domain parameters. Student’s t-test was applied. Results:There were no significant differences in HRV measures between two groups, over 24-hour period and day-time and night-time period. But the hourly HRV measures showed a transient decrease of LF, LFnorm and LF/HF ratio in patients group compared to normal control group. Conclusions:These results indicate that patients with neurocardiogenic syncope or presyncope suffer from temporarily decreased sympathetic tone with normal parasympathetic tone. So, transient additive change of autono-mic nervous tone may cause syncope or presyncope in these patients. (Korean Circulation J 2000;30(6):716-723)

Relief of chronic pain may be accompanied by an increase in a measure of heart rate variability.

D ecreased heart rate variability (HRV) is generally associated with compromise of cardiovascular feedback systems (1,2). Changes in HRV can be caused by congestive heart failure (1), myocardial infarction (3,4), diabetic autonomic dysfunction (5), aging (6), anesthesia (7,8), and surgery (9–12). We report initial findings using new techniques to measure HRV that we believe warrant additional investigation in a broad range of conditions involving pain. The acute effect of pain to increase heart rate is well known. We hypothesized that there may be adaptive effects of chronic pain on the autonomic regulation of the cardiovascular system that could be reversed by analgesia, and we examined whether the acute relief of chronic pain affects HRV. We monitored several measures of HRV because these can differ in their ability to detect different conditions affecting the cardiovascular system (4,6,9,12–15). Traditional measures of HRV include sd (1,2). More recent measures estimate dimension (8,13,15,16) and entropy (6,8,9,15,17,18).

Heart rate variability in diabetic and non-diabetic renal transplant patients.

Heart rate variability (HRV) has been used to investigate the autonomic modulation of heart rate. Diminished HRV has been observed in diabetic autonomic neuropathy, a condition associated with increased mortality. Uraemia is associated with impaired autonomic function, but reports on the effects of uraemia on HRV are scarce. HRV and its circadian variation were studied in 12 diabetic and 11 non-diabetic renal transplantation and in 12 control patients. HRV in time and frequency domains was determined from 24-hour ECG recordings. In the diabetic group, all time domain and frequency domain measures of HRV were markedly reduced (P < 0.05), when compared with the control group, and the circadian variation of HRV was absent. The mean (SD) amplitudes (ms) in the frequency bands were: high frequency: 3 (1), 6 (3) and 15 (3); low frequency: 9 (7), 16 (10) and 25 (8); very low frequency: 14 (8), 23 (12) and 30 (11) in the diabetic and non-diabetic uraemic and in the control patients, respectively. In non-diabetic uraemic patients, a tendency to reduced HRV was observed, but no statistical differences in HRV measures were found when compared with the control group. The severe impairment of HRV in patients with end-stage diabetic nephropathy is probably due to autonomic neuropathy and partly also to the co-existing heart diseases. It may be a contributing risk factor for ventricular arrhythmias and sudden death in these patients. Uraemia alone causes similar but less severe changes in HRV.