Domain Heart Rate Variability Measures Research Articles

Cardiac Autonomic Function in Adults Born Preterm

To evaluate cardiac autonomic function in adults born preterm. We studied the association between prematurity and cardiac autonomic function using heart rate variability measurements in 600 adults (mean age of 23.3years) from a geographically based cohort in Northern Finland. There were 117 young adults born early preterm (<34weeks), 207 born late preterm (34-36weeks), and 276 born at term (≥37weeks, controls). Autonomic function was analyzed by calculating time and frequency domain heart rate variability measurements using linear regression. Compared with controls, the mean difference in root mean square of successive differences (indicating cardiac vagal activity) was -12.0% (95% CI -22.2%, -0.5%, adjusted for sex, age, source cohort, and season P=.04) for the early preterm group and -7.8% (-16.8%, 2.0%, P=.12) for the late preterm group. Mean differences with controls in low frequency power (indicating cardiac vagal activity, including some sympathetic- and baroreflex-mediated effects) were -13.6% (-26.7%, 1.8%, P=.08) for the early preterm group and -16.4% (-27.0%, -4.3%, P=.01) for the late preterm group. Mean differences in high frequency power (quantifying cardiac vagal modulation in respiratory frequency) were -19.2% (-36.6%, 2.9%, P=.09) for the early preterm group and -13.8% (-29.4%, 5.3%, P=.15) for the late preterm group. Differences were attenuated when controlled for body mass index and physical activity. Our results suggest altered autonomic regulatory control in adults born preterm, including those born late preterm. Altered autonomic regulatory control may contribute to increased cardiovascular risk in adults born preterm.

Heart Rate Variability in Healthy Non-Concussed Youth Athletes: Exploring the Effect of Age, Sex, and Concussion-Like Symptoms.

Heart rate variability (HRV) is a non-invasive neurophysiological measure of autonomic nervous system regulation emerging in concussion research. To date, most concussion studies have focused on the university-aged athlete with no research examining healthy active youths. Corroborating changes in HRV alongside traditional subjective self-report measures (concussion symptoms) in the non-concussed state provides a foundation for interpreting change following concussion. The objectives were to (1) explore the influence of age and sex on HRV and (2) examine the relationship between HRV and baseline/pre-injury concussion symptom domains (physical, cognitive, emotional, and fatigue) in healthy youth athletes. Healthy, youth athletes 13-18 years of age [N = 294, female = 166 (56.5%), male = 128 (43.5%)] participated in this cross-sectional study. Age, sex, and concussion-like symptoms were collected as part of a baseline/pre-injury assessment. The Post-Concussion Symptom Inventory-SR13 (PCSI-SR13) was used to collect domain scores for physical, cognitive, emotional, and fatigue symptoms. HRV was collected for 24 h. HRV measures included time (SDNN, RMSSD, and pNN50) and frequency (HF, HFnu, LF, LFnu, and total power) domain HRV measures. Variables were logarithmically transformed to increase robustness of linear regression models. Older youth participants displayed significantly higher HRV compared to younger participants (p < 0.05). Females displayed significantly lower HRV compared to males (p < 0.05). A significant interaction effect between concussion-like symptoms and HRV indicated differential patterns as a function of sex (p < 0.05). Youth athletes who reported more cognitive symptoms had lower HRV (p < 0.05). HRV was found to have a significant relationship with a traditional clinical measure (subjective self-report of concussion-like symptoms) utilized in concussion assessment and management. Baseline/pre-concussion trends in HRV were significantly associated with age and sex, highlighting the value in understanding key demographic factors within the context of concussion-like symptoms.

Heart rate variability and baroreceptor reflex sensitivity in early- versus late-onset preeclampsia.

ObjectiveTo determine whether there are differences in autonomic nervous system function in early- versus late-onset preeclampsia.MethodsMatched case-control study. Cases were defined as singleton pregnancies with preeclampsia at < 34+0 weeks of gestation (early-onset preeclampsia) and ≥ 34+0 weeks of gestation (late-onset preeclampsia). For each case in each of the preeclampsia subgroups, three „control”uncomplicated singleton pregnancies were matched by maternal age, height, and week of gestation. Blood pressure and heart rate were measured continuously for 30 minutes in each participant. Baroreceptor reflex sensitivity (assessed using sequence technique), time and frequency domain heart rate variability measures, as SDNN, RMSSD, LFRRI, HFRRI and LF/HFRRI of R-R intervals, were compared between groups (p<0.05 significant).Results24 women with preeclampsia (10 with early-onset and 14 with late-onset preeclampsia) and 72 controls were included in the study. SDNN, RMSSD and HFRRI were significantly higher in the late-onset preeclampsia group compared to gestational age matched controls (p = 0.033, p = 0.002 and p = 0.018, respectively). No significant differences in SDNN RMSSD and HFRRI between early-onset preeclampsia group and gestational age matched controls were observed (p = 0.304, p = 0.325 and p = 0.824, respectively). Similarly, baroreceptor reflex sensitivity was higher in late-onset preeclampsia compared to controls at ≥ 34 weeks (p = 0.037), but not different between early-onset preeclampsia compared to controls at < 34 weeks (p = 0.50).ConclusionsHeart rate variability and baroreceptor reflex sensitivity are increased in late- but not early-onset preeclampsia compared to healthy pregnancies. This indicates a better autonomic nervous system mediated adaptation to preeclampsia related cardiovascular changes in late-onset disease.

Effect of Early Bereavement on Heart Rate and Heart Rate Variability

Early bereavement is associated with increased cardiovascular events. The mechanism, however, has not been well studied. We assessed whether bereavement is associated with an increased heart rate (HR) and decreased heart rate variability that might contribute to increased cardiovascular risk. A total of 78 bereaved spouses and parents (55 women and 23 men; aged 34 to 87 years, mean 65) were studied with 24-hour Holter monitoring within 2 weeks of bereavement (acute) and at 6 months. Their findings were compared to those from a nonbereaved reference group (52 women and 27 men) aged 33 to 91 years (mean 63.6). All participants were in sinus rhythm. We assessed the mean HR, atrial and ventricular arrhythmias, and both time and frequency domain heart rate variability measures. Acute bereavement was associated with increased 24-hour HR (mean ± SE, 75.1 ± 1.1 vs 70.7 ± 1.0; p = 0.004) and reduced heart rate variability, as indicated by lower standard deviation of the NN intervals index (median 45.4 vs 49.9, p = 0.017), total power (7.78 ± 0.10 vs 8.02 ± 0.09, p = 0.03), very low frequency (7.23 ± 0.09 vs 7.44, p = 0.046) and low frequency (5.76 ± 0.12 vs 6.16 ± 0.09, p = 0.01). At 6 months, the bereaved had a significantly lower HR (p = 0.001) and increased standard deviation of the NN intervals index (p = 0.02), square root of the mean square of differences of successive intervals (p = 0.045), number of interval differences of successive NN intervals >50 ms divided by the number of NN intervals (p = 0.039), low-frequency power (p = 0.02), and high frequency (p = 0.002) compared to the initial acute levels. In conclusion, the present study, the first to report 24-hour HR monitoring in the early weeks of bereavement, has demonstrated increased HR and altered autonomic function that might contribute to the increased cardiovascular events in early bereavement.

Prevalence of ventricular arrhythmias and heart rate variability pattern in chronic heart failure

This study was carried out to determine the prevalence of ventricular arrhythmias and heart rate variability pattern in patients on treatment for chronic heart failure. Twenty four hour ambulatory electrocardiograms were recorded in 60 patients with chronic heart failure and echocardiography left ventricular ejection fraction of less than 45%.Sixty age and sex- matched individuals with no obvious evidence of underlying cardiac disease were also evaluated for comparison. Premature ventricular complexes (PVCs) were evident in all subjects being infrequent [ < 30 PVCs per hour], in 21 (35%) and frequent [ > 30 PVCs per hour] in 39 (65%).Multiform extra systoles were recorded in 44 (73.3%) subjects, ventricular couplets in 50 (83.4%), and non-sustained ventricular tachycardia (NSVT) in 28 (46.7%) of the 60 subjects. Among the controls, PVCs were seen in 27(45%) and were all infrequent. None of the controls had multiform extra systole, ventricular couplets or NSVT. Significant inverse relationships were found between ejection fraction and PVC per h ( P-value < 0.001), ventricular couplet per 24h (P-value < 0.001) and NSVT per hour (P-value 0.002).Time domain heart rate variability measures i.eMean Standard Deviation of Normal to Normal RR Interval (SDNN), mean Percentage of Adjacent NN Intervals in a 24 hour recording which differ by at least 50ms (pNN550) , mean Root Mean Square Successive Difference in RR Interval (rMSSD) were significantly lower in the subjects compared to the controls. The corresponding P-values were < 0.001, < 0.001, < 0.001 respectively. A significant positive correlation was found between EF and SDNN ( P-value < 0.001), pNN50 (P-value 0.044) and rMSSD (P-value < 0.001). This study showed that ambulant out patients with chronic heart failure, have significantly higher prevalence of ventricular arrhythmias and narrow heart rate variability compared to healthy individuals of comparable age and gender.

Study of cardiac autonomic function in drug‐naïve, newly diagnosed epilepsy patients

Epilepsy is associated with ictal autonomic dysfunction which may extend into the inter-ictal period. Antiepileptic drugs have often been blamed for cardiac autonomic dysfunction in epilepsy patients. In this study we have investigated cardiac autonomic parameters in order to evaluate autonomic functions of drug-naïve epilepsy patients. Twenty drug-naïve patients (15 males and 5 females) with epilepsy, and an equal number of age and gender matched controls, were evaluated for short-term resting heart rate variability and conventional cardiovascular autonomic measurements. The mean age of patients was 29.30 +/- 9.80 yrs (17-55 yrs), mean age at seizure onset was 19.70 +/- 9.15 yrs (3-40 yrs) and mean length of time since last seizure was 5.60 +/- 7.00 days (1-30 days). While there was no difference in the resting heart rate or conventional autonomic test parameters, time domain heart rate variability measurements showed a decreased percentage of R-R intervals of less than 50 ms and root mean square of R-R intervals in patients, when compared to controls. Frequency domain parameters showed a decreased total power (patients: 1,796.58 +/- 1,052.45 ms2; controls: 2,934.23 +/- 1,767.06 ms2, p = 0.008). Parameters indicative of decreased vagal tone, i.e. decreased high frequency power and increased low to high frequency ratio (patients: 1.69 +/- 0.94; controls: 1.14 +/- 0.64, p = 0.045), were observed among patients compared to controls. Subtle but definite cardiac autonomic dysfunction, especially in vagal tone, was identified in drug-naïve, new-onset epilepsy patients. Seizures can cause long-term and often progressive cardiac autonomic dysfunction which may be independent of concomitant antiepileptic drugs.

Effect of disease activity and position on autonomic nervous modulation in patients with systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) are known to have lower heart rate variability and impaired vagal modulation, and right lateral position has been shown to lead to a higher vagal modulation than supine position in healthy subjects and patients with cardiovascular diseases. This study evaluated the effect of disease activity and different recumbent positions on cardiac autonomic nervous modulation by heart rate variability analysis in patients with SLE. Thirty-five female patients with SLE and 33 female controls were enrolled in this study. Electrocardiogram was recorded during supine, left lateral, and right lateral positions for 15 min. Both time and frequency domains heart rate variability measures were calculated. The normalized high-frequency power was used as the index of vagal activity, and the low-/high-frequency power ratio as the index of sympathovagal balance. We found that patients with SLE had lower indices of time domain heart rate variability measures and lower low-frequency power, high-frequency power, and normalized high-frequency power than control subjects. SLE patients with lower serum albumin had lower normalized high-frequency power and higher low-/high-frequency power ratio. In patients with SLE, right lateral position could lead to higher high-frequency power, normalized high-frequency power, and lower low-/high-frequency power ratio than supine position. In addition, the lower the normalized high-frequency power in supine position the patient had, the greater the increase in normalized high-frequency power when the position of the patient was changed from supine to right lateral. Thus, serum albumin level might be used as a potential disease severity index of SLE, and right lateral position can lead to higher vagal modulation and lower sympathetic modulation, renin-angiotensin-aldosterone modulation, and vagal withdrawal than supine position in patients with SLE. Right lateral position can be used as an efficient and physiological vagal enhancer in SLE patients with depressed vagal modulation.

Heart rate variability in carcinoid heart disease

Time domain heart rate variability measurements and echocardiographic studies were performed in 35 patients with carcinoid syndrome. Carcinoid heart disease was present in 18 patients (51%). Heart rate variability parameters (standard deviation of all normal RR intervals, percentage of the number of pairs of adjacent normal RR intervals differing by >50 ms) were significantly reduced in patients with than in those without carcinoid heart disease.

Short- and long-term reproducibility of time and frequency domain heart rate variability measurements in normal subjects.

To obtain data relating to the reproducibility of the time and frequency domain measurements obtained from 10-min ECG recordings. Eighteen normal volunteers underwent evaluations of time and frequency domain heart rate variability 2 weeks and 7 months after baseline analysis. The time domain parameters were mean NN, the standard deviation of NN intervals, the percentage of successive NN intervals > 50 ms and the root mean square successive difference of NN intervals. The frequency domain evaluations (total power, low frequency, and high frequency) were made by means of both the Fast Fourier Transform algorithm (FFT) and the autoregressive method (AR) from 10-min ECG recordings made under three different conditions: rest, controlled respiration, and after a passive head-up tilt test. Reproducibility was evaluated by means of the interclass correlation coefficient (ICC), comparing baseline values with the results obtained at the second week and the seventh month. Time domain evaluation were also made from 10-min ECG. All of the time domain measurements had an ICC > or = 0.75, except for the standard deviation of NN intervals, which had an ICC of 0.57. The frequency domain parameters obtained by means of either FFT or AR showed similar reproducibility. Low frequency was reproducible under all three conditions, total power only at rest, and high frequency only during controlled respiration. The reproducibility of frequency domain parameters depends on the analysed condition. These results are of primary importance when the effects of drugs or other interventions on heart rate variability are under investigation.