Significant Differences In Heart Rate Variability Parameters Research Articles

Effects of posture on heart rate variability in non-frail and prefrail individuals: a cross-sectional study

BackgroundFrailty is an aging-related syndrome leading to high mortality in older adults. Without effective assessment and prevention of frailty, the incidence of frailty and relevant adverse outcomes will increase by 2050 as worldwide populations age. Although evidence suggested heart rate variability (HRV) is a potential measure of frailty, the role of HRV in frailty assessment remains unclear because of controversial findings. This study examined the effects of posture on HRV parameters in non-frail and prefrail individuals to understand the role of HRV in assessing frailty.MethodsForty-six participants aged ≥ 50 years were recruited between April and August 2022. Frailty was defined using Fried’s criteria. HRV was measured in standing, sitting, and lying postures, respectively, using a Polar Watch, and analyzed using Kubios HRV Standard 3.5.0 (Kubios). The five most commonly used parameters were examined, including standard deviations of all normal-to-normal intervals (SDNN), root mean square of the successive differences (RMSSD), low frequency (LF), high frequency (HF), and LF/HF. Independent t-tests and Mann–Whitney tests were used for inter-group comparisons. Friedman tests were used for intra-group comparisons across postures.ResultsThe non-frail group showed significant differences in HRV parameters across postures (all p < 0.05), whereas the prefrail group did not demonstrate any difference (all p > 0.05). The differences in the non-frail group included higher RMSSD and HF in the lying posture compared to those in the standing posture (29.54 vs 21.99 p = 0.003, 210.34 vs 96.34 p = 0.001, respectively), and higher LF and LF/HF in the sitting posture compared to those in the lying posture (248.40 vs 136.29 P = 0.024, 1.26 vs 0.77 p = 0.011, respectively).ConclusionsThe effects of posture on HRV were blunted in the prefrail group, which suggests an impaired cardiac autonomic functioning. Measuring the effects of posture on HRV parameters may contribute to frailty assessment. However, further evidence from larger cohorts and including additional HRV parameters is needed.

Altered Low Frequency Heart Rate Variability Associated with Agoraphobia in Panic Disorder: A Retrospective Study.

This study aimed to compare the clinical features of panic disorder (PD) with comorbid agoraphobia to those of PD alone. We focused on autonomic nervous system (ANS) alterations reflected in heart rate variability (HRV) and executive function deficits reflected in the Stroop test. We retrospectively compared psychometric features, Stroop test results, and resting-state HRV across three groups: a subclinical group with anxiety attack history, a PD group without agoraphobia, and a PD group with agoraphobia. The subclinical group included 10 male and 34 female, the PD without agoraphobia group included 17 male and 19 female, and the PD with agoraphobia group included 11 male and 18 female. The PD with agoraphobia group had higher Symptom Checklist-95 scores than the other groups. Both PD groups had longer reaction times in the Stroop test than the subclinical group. There were no significant differences in HRV parameters between the PD groups with and without agoraphobia. Compared with the subclinical group, the PD with agoraphobia group showed significantly lower values of the natural logarithm of low-frequency HRV. Our results do not support that executive function deficits and ANS alterations are more pronounced with comorbid agoraphobia among PD groups. However, PD with agoraphobia patients showed more complex and severe clinical symptoms in their self-reports. Compared with the subclinical group, PD patients with agoraphobia showed specific features in the natural logarithm of low-frequency HRV. Our findings suggest that agoraphobia comorbidity should be considered when evaluating or treating patients with PD.

Retrospective analysis of autonomic dysfunction in epilepsy patients from neurophysiological recordings

Autonomic dysfunction is often associated with seizures in patients with epilepsy. Autonomic dysfunction during seizures can cause serious events like cardiac arrest and sudden unexplained death. Early detection of autonomic dysfunction is crucial to avoid such medical emergencies. In our study, we analyzed the heart rate variability (HRV) in physiological recording during the preictal, ictal and postictal periods. A total of 142 seizures with various semiologies recorded from 49 epilepsy patients were included. Time-domain measurements including mean hear rate (HR), RR interval (RRI), root-mean-square of successive R-R interval differences (RMSSD), The standard deviation of N-N intervals (SDNN) and percentage of successive RR intervals that differ by more than 50 ms(pNN50) were analyzed at different time points, 20 minutes before the seizure, 1 minute before the seizure, during the seizure and 20 minutes after the seizure. We observed there was a significant difference in HRV parameters during and just before the seizure onset (RMSSD with p-value&lt;0.001 and SDNN with p-value&lt;0.001). We also observed that there was a suppression of parasympathetic activity and activation of sympathetic stimulation in the ictal and peri-ictal period, which was characterized by an elevation in the mean heart rate (HR), whereas the mean RRI showed an inversely proportional trend. There was a reduction in mean RMSSD, SDNN and pNN50 prior to seizure onset and was more pronounced in generalized seizures as compared to focal seizures with preserved or impaired awareness. There was a greater sympathetic activation and parasympathetic inhibition during an epileptic seizure in females as compared to male patients. These findings suggest that autonomic dysregulation was increased during a generalized seizure when compared to a focal seizure. HRV analysis can be used as a valid method for quantifying central influences on the autonomic nervous system and its cardiac control. A major advantage of electrocardiogram (ECG)-based seizure detection is that the ECG is an essentially easier signal to obtain, with a higher signal-to-noise ratio than EEG (electroencephalogram). Based on the inferences from this study future studies could be done to build machine learning models which could form the base for the development of wearable seizure prediction devices.

The role of revascularization on short-term Heart Rate Variability (HRV) and Signal Averaged Electrocardiogram (SAECG) in Stable Coronary Artery Disease (CAD)

Background: Revascularization in patients with stable coronary artery disease (SCAD) can reduce myocardial ischemia and improves the autonomic nervous system, which can be measured by heart rate variability (HRV) and signal-averaged electrocardiogram (SAECG). This study aimed to investigate the effect of revascularization on HRV and SAECG in patients with SCAD. Methods: This is a single-center prospective cohort study. Revascularization refers to percutaneous coronary intervention (PCI). The primary outcome of this study is the change in short-term HRV and SAECG from before revascularization to after revascularization. HRV and SAECG measurement was performed for 10 minutes before PCI and one-month post-PCI. Data were analyzed using SPSS version 23 for Windows. Results: There are 30 patients included in this study, and 46.7% underwent incomplete PCI. There was no significant difference in HRV parameters in the time domain method. In the frequency domain, only the LF/HF ratio changed significantly from 3.5±2.6 before PCI to 2.16±1.9 after PCI, with a 1.33 decrease in LF/HF (p=0.007). Subgroup analysis was performed for patients receiving complete and incomplete revascularization. In patients who received complete revascularization, there was a significant difference in LF/HF ratio change of 1.6±2.28 (p=0.013). In patients that receive incomplete revascularization, there is a significant increase in HF 37.8±57.3 (p=0,028). In terms of SAECG parameters, there is no significant difference between before and after PCI in both primary and subgroup analysis. Conclusion: Revascularization resulted in a significant reduction in LF/HF ratio assessed by short-term HRV. There was no benefit of revascularization in terms of SAECG parameters.

Heart rate and heart rate variability in patients with chronic inflammatory joint disease: the role of pain duration and the insular cortex

BackgroundChronic inflammatory joint diseases (CIJD) have been linked to increased cardiovascular morbidity and mortality. A decisive reason could be a dysregulation of the autonomic nervous system, which is responsible for the control of cardiovascular function. So far, the cause of changes in autonomic nervous system functions remains elusive. In this study, we investigate the role of chronic pain and the insular cortex in autonomic control of cardiac functioning in patients with CIJD.MethodsWe studied the autonomic nervous system through the assessment of heart rate and heart rate variability (HRV) at rest and under cognitive stimulation. Furthermore, we investigated insular cortex volume by performing surface-based brain morphometry with FreeSurfer. For this study, 47 participants were recruited, 22 individual age- and sex-matched pairs for the magnetic resonance imaging analyses and 14 for the HRV analyses. All available patients’ data were used for analysis.ResultsPain duration was negatively correlated with the resting heart rate in patients with chronic inflammatory joint diseases (n = 20). In a multiple linear regression model including only CIJD patients with heart rate at rest as a dependent variable, we found a significant positive relationship between heart rate at rest and the volume of the left insular cortex and a significant negative relationship between heart rate at rest and the volume of the right insular cortex. However, we found no significant differences in HRV parameters or insular cortex volumes between both groups.ConclusionsIn this study we provide evidence to suggest insular cortex involvement in the process of ANS changes due to chronic pain in CIJD patients.The study was preregistered with the German Clinical Trials Register (https://www.drks.de; DRKS00012791; date of registration: 28 July 2017).

Study of the physiological effects of shift work using the HRV analysis method

Shift work in industry and services cannot be avoided, but the adverse health effects of shift work are well known. The results of workplace physiological measurements in the Hungarian solid mineral mining oil and gas extraction and processing industry was, carried out under the coordination of the Scientific Committee on Mining Health and Ergonomics of the Hungarian Academy of Sciences, The Committee studiedy the variations of age and life characteristics of the workers, the various working conditions and environment and the heart rate variability (HRV) parameters. Our workplace studies covered 8, 12 and 24-hour shift works alike during morning, afternoon and night shifts with 2, 5 or 7 days per shift. In the evaluation, the significant differences in HRV parameters reflecting different physiological conditions, working conditions and work environment are presented for the morning only (control group) and the shift work groups. Evaluation of the results of the measurements carried out at the workplaces adjusted to the actual work schedule using known methods of mathematical statistics made it possible to investigate the effects of different circumstances and conditions. Based on the reviewed research results regarding the health effects of shift work, IARC/WHO concluded in 2010 that shift work was probably carcinogenic to humans (category 2A) - a recommendation that was changed to night shift work in 2019, based on the research results revealed in the meantime. Our studies call attention to the potential for using the results of new methods developed through innovation and to the justification for their use in occupational health.

Autonomic Nervous System Function in Newly Diagnosed Multiple Sclerosis: Association With Lipid Levels and Insulin Resistance.

Autonomic nervous system (ANS) disorders are common in multiple sclerosis (MS). Previous studies showed differences in insulin resistance (IR) and lipoprotein levels in MS subjects compared to controls. Lipolysis caused by increased sympathetic activity could be one of the possible linking mechanisms leading to dyslipidemia in MS. Our study aimed to evaluate ANS activity in the context of glucose and lipid metabolism in people with MS. We prospectively measured short-term heart rate variability (HRV), fasting lipoprotein concentrations, and calculated IR indices based on plasma glucose and insulin levels during oral glucose tolerance test (oGTT) in 32 patients with MS and 29 healthy controls matched for age, sex and body mass index in our study. There was no significant difference in HRV parameters and lipoprotein levels between MS and controls. A significant positive correlation was found between low/high-frequency power ratio (LF/HF) and triglycerides (r=0.413, p=0.021) in MS subjects but not in controls. A significantly lower whole-body insulin sensitivity index (ISIMat) was found in patients with MS compared to the control group (7.3±3.7 vs. 9.8±5.6, p=0.041). No significant correlations were found between LF/HF and IR parameters. In MS subjects, the positive correlation of LF/HF with triglycerides could reflect the effects of sympathetic activity on lipolysis. Positive correlations of sympathetic activity with increased lipoprotein levels could rather reflect processes associated with immune system activation/inflammation, than processes involved in glucose homeostasis maintenance.

Heart rate variability in patients with refractory epilepsy: The influence of generalized convulsive seizures

ObjectivePatients with epilepsy, mainly drug-resistant, have reduced heart rate variability (HRV), linked to an increased risk of sudden death in various other diseases. In this context, it could play a role in SUDEP. Generalized convulsive seizures (GCS) are one of the most consensual risk factors for SUDEP. Our objective was to assess the influence of GCS in HRV parameters in patients with drug-resistant epilepsy. MethodsWe prospectively evaluated 121 patients with refractory epilepsy admitted to our Epilepsy Monitoring Unit. All patients underwent a 48-hour Holter recording. Only patients with GCS were included (n = 23), and we selected the first as the index seizure. We evaluated HRV (AVNN, SDNN, RMSSD, pNN50, LF, HF, and LF/HF) in 5-min epochs (diurnal and nocturnal baselines; preictal – 5 min before the seizure; ictal; postictal – 5 min after the seizure; and late postictal – >5 h after the seizure). These data were also compared with normative values from a healthy population (controlling for age and gender). ResultsWe included 23 patients, with a median age of 36 (min-max, 16–55) years and 65% were female. Thirty percent had cardiovascular risk factors, but no previously known cardiac disease. HRV parameters AVNN, RMSSD, pNN50, and HF were significantly lower in the diurnal than in the nocturnal baseline, whereas the opposite occurred with LF/HF and HR. Diurnal baseline parameters were inferior to the normative population values (which includes only diurnal values). We found significant differences in HRV parameters between the analyzed periods, especially during the postictal period. All parameters but LF/HF suffered a reduction in that period. LF/HF increased in that period but did not reach statistical significance. Visually, there was a tendency for a global reduction in our patients’ HRV parameters, namely AVNN, RMSSD, and pNN50, in each period, comparing with those from a normative healthy population. No significant differences were found in HRV between diurnal and nocturnal seizures, between temporal lobe and extra-temporal-lobe seizures, between seizures with and without postictal generalized EEG suppression, or between seizures of patients with and without cardiovascular risk factors. Significance/conclusionOur work reinforces the evidence of autonomic cardiac dysfunction in patients with refractory epilepsy, at baseline and mainly in the postictal phase of a GCS. Those changes may have a role in some SUDEP cases. By identifying patients with worse autonomic cardiac function, HRV could fill the gap of a lacking SUDEP risk biomarker.

Comparison of Heart Rate Variability among Young Malay Male Adult with Different BMI and Level of Adiposity

INTRODUCTION: Subclinical changes that occur in the heart at an early age may provide valuable information to outline prevention strategies for cardiovascular diseases. Heart rate variability (HRV) reflects regulation of autonomic balance, heart, and vascular tone, which are the determinants of blood pressure. Therefore, this study aimed to determine the difference in heart rate variability (HRV) of Malay male young adult with their BMI and adiposity level. MATERIALS AND METHODS: A total of 201 Malay male young adult aged between 19 to 24 years old were screened and their BMI and adiposity level were measured. Three non -invasive tests; Valsalva Manoeuvre, orthostatic response and 30/15 ratio of heart rate were performed. Short term HRV time and frequency domains were recorded. RESULTS: Despite few significant differences in HRV parameters of overweight/obese subjects, the result is inconclusive to conclude any reduced variability. However, those with high adiposity regardless of their BMI reported significantly lower mean of R -R SD in time domain and lower mean of LF/HF ratio in frequency domain. The orthostatic reflex results revealed that high adiposity subjects had significantly lower mean of LF and HF. A decrement of -0.28 ms2 HF/LF during Valsalva manoeuvre, -0.35 LF ms2 in orthostatic reflex and 0.33 ms2 in orthostatic reflex per 1% of body fat percentage were observed. CONCLUSION: HRV parameters were inversely proportional to the adiposity level which was suggestive of modulation of sympathetic function can occur at an early age.

Cardiac Autonomic Neuropathy Is Not Reversed by Euglycemia Following Islet Transplantation.

Cardiac autonomic neuropathy (CAN) is a significant cause of morbidity and mortality for people with type 1 (T1D) and type 2 (T2D) diabetes. Heart rate variability (HRV) has been shown to be a marker of CAN with 24-hour Holter monitoring being a robust modality to assess HRV. To investigate the impact of hypoglycemia on CAN and its potential reversibility with islet transplantation, we compared HRV assessment by 24-hour Holter monitor on a total of 109 subjects from 5 cohorts: (1) T1D with recurrent severe hypoglycemia and on waiting list for islet transplant, (2) T1D following islet cell transplantation (ICT), (3) T2D without hypoglycemia, (4) individuals with prediabetes, and (5) controls without diabetes. SD of the normal-normal interval, square root of the mean squared differences of successive normal-normal intervals (rMSSD) and total spectral power were analyzed. There was no significant difference in HRV parameters between T1D subjects and T1D post ICT suggesting CAN is not reversible at a median of 4 years postislet transplant. There was a significant difference in controls and T1D in rMSSD and between controls and T2D in total power. The differential effect on rMSSD in T1D and T2D suggests potential greater impact of hypoglycemia on rMSSD. Achieving euglycemia after ICT may not reverse CAN once established with no significant difference in HRV parameters at a median of 4 years postislet transplant. Differential effects of T1D as compared with T2D on CAN were identified.

Correlation of autonomic function tests with age, sex, anthropometry, and body composition in sedentary office workers

Background: Sedentary lifestyle leads to autonomic dysfunction with sympathetic hyperactivity, which leads to increased morbidity. Aims and Objectives: This study was aimed to investigate the relationship of autonomic function tests with age, sex, and anthropometric measurements in sedentary workers. Materials and Methods: This study was conducted on 50 healthy sedentary office workers aged between 20 and 50 years. Their anthropometric and parameters of body composition were calculated. Autonomic functions were assessed by the recording of frequency domain parameters of heart rate variability (HRV). Results: Among the HRV parameters, the mean low frequency (LF), high frequency (HF) LF/HF ratio, and total power were 453 ± 428 ms², 406 ± 612 ms², 2.15 ± 2.64, and 1432 ± 1238 ms², respectively. There was no significant difference in HRV parameters of male and female subjects (P > 0.05). HF, LF, and LF/HF ratio decreased significantly with age (r = −0.422; P = 0.032). No significant correlation was found between HRV parameters and anthropometric parameters (P > 0.05). Among the parameters of body composition, specifically in case of fat-free mass, the LF/HF ratio was significantly increased (r = 0.582, P = 0.001). Conclusion: Aging process causes a decrease in HRV. As the weight increases, LF/HF ratio increases indicating increased sympathetic activity.

Reduction in Heart Rate Variability in Autosomal Dominant Polycystic Kidney Disease

Introduction: Cardiovascular disease is one of the main causes of morbidity and mortality in patients with autosomal dominant polycystic kidney disease (ADPKD). Autonomic dysfunction is associated with an increased risk for all cardiovascular events in the general population and can be evaluated with heart rate variability (HRV). Objective: To evaluate HRV in ADPKD patients with mild hypertension versus hypertensive patients with organ damage and healthy controls (HC). Materials and Methods: We have enrolled 65 patients: 21 ADPKD patients (10 males), 20 patients with hypertension (14 males), and 24 HC (10 males). Biochemical analysis, clinical evaluation, anthropometric data, intima-media thickness, 24-h ECG Holter recording, and echocardiography were investigated at the time of enrollment. Results: No significant differences in HRV parameters were found between ADPKD with mild hypertension and hypertensive patients with organ damage. The median of HRV variables in time domain as SDNN (global autonomic activity) was significantly lower in ADPKD and hypertensive patients than HC (p < 0.05). In the frequency domain analysis, low frequency (LF), which mainly reflects the sympathetic component, showed higher values in ADPKD and hypertensive patients than HC during the night (p < 0.01). During the night, the sympathovagal balance, LF/high frequency (HF), showed higher values in ADPKD and hypertensive patients than HC (p < 0.0001). Conversely, LF day was lower in ADPKD and hypertensive patients than HC (p < 0.01). HF, which mainly reflects the parasympathetic component, was lower in ADPKD and hypertensive patients during the night than HC (p < 0.0001). Conclusions: HRV reduction is present in ADPKD patients with mild hypertension in the absence of organ damage. The evaluation of sympathovagal balance can provide novel information on the cardiovascular risk in ADPKD patients in addition to classical risk factors.

A 6-weeks Treatment Program Improves HRV in Eating Disorder Patients

Background: Eating disorders such as anorexia nervosa present with a significant cardiovascular associated risk of sudden cardiac death. Bradycardia is a serious complication of eating disorders. Methods: Eating Disorder (ED) patients were admitted to a 6-week treatment program and assessed for of heart rate variability (HRV) at entrance to the program and at discharge from hospital. Linear heart rate variability measures were determined using Kubios software from Lead 3 ECG recordings following a 5-minute rest period. Nonparametric statistics were applied and significance set at p < 0.05. Results: No significant differences in HRV parameters were noted for the control group following the 6-week treatment program. For the ED group, mean RR interval length decreased significantly following treatment compared (median ± IQR; -64 ± 76; p = 0.002). Sympathovagal function was abnormal in the ED group on admission but improved following treatment, showing a decrease in RMSSD (median ± IQR; -9 ± 18; p = 0.048) and SD1 (median ± IQR; -6 ± 13; p = 0.048). Sample entropy, a, measure of heart rate complexity did not change significantly. Conclusion: At admission to hospital the ED group was more parasympathetic during rest compared to controls, but they became more sympathetic after the intervention and approached the HRV measures of the controls.

Effect of a weight reduction program on baseline and stress-induced heart rate variability in children with obesity.

Autonomic dysregulation is a well-established feature in adults with obesity but not in children. Since this dysregulation could contribute to weight dynamics, this study aimed to compare autonomic regulation in children with obesity and normal-weight peers and to track autonomic status during weight reduction. Sixty children with obesity and 27 age- and sex-matched normal-weight healthy participants were included. Heart rate variability (HRV) was assessed at baseline and during a mental stress test and a subsequent recovery period. Children with obesity were investigated both upon admission and discharge. Upon admission, no significant differences in HRV parameters were found for normal-weight participants and those with obesity. Inpatient treatment led to significant changes in HRV with increase in general variability (standard deviation of the normal-to-normal interval (SDNN), P < 0.001) as well as of parasympathetic regulation (root mean square successive difference (RMSSD) and high frequency power (logHF), P < 0.01). Children with obesity had sympathetic activation similar to normal-weight controls during mental stress with subsequent return to baseline values, and weight loss did not affect this profile. A weight reduction program induced a change in autonomic activity in children with obesity toward parasympathetic dominance but had no influence on autonomic nervous system reactivity during stress conditions.

Einfluss des therapeutischen Qi auf die Herzratenvariabilität bei Akupunktur: Eine randomisierte kontrollierte Studie

Hintergrund: In einer kürzlich durchgeführten Studie konnten Probanden bei der Akupunktur eine Stimulation mittels «therapeutischem Qi» wahrnehmen, obwohl mechanische und psychologische Faktoren ausgeschlossen wurden. Nun untersuchten wir, ob das therapeutische Qi auch die Herzratenvariabilität messbar beeinflusst. Methoden: Es handelte sich um eine randomisierte, kontrollierte, einfach verblindete Crossover-Studie mit 30 Probanden. Mithilfe einer Vorrichtung wurde eine Akupunkturnadel in den Akupunkt Pe6 eingeführt. Mit einer weiteren Vorrichtung wurde der herausragende Teil der Nadel so fixiert, dass bei Berührung des Nadelendes die Übertragung von mechanischen Bewegungen auf die Nadelspitze ausgeschlossen werden konnte. Bei der anschließenden Prüfintervention wurde das Nadelende zur Stimulation des Qi durch den Therapeuten berührt, bei der Kontrollintervention wurde die Nadel nicht berührt, sodass das Qi nicht stimuliert wurde. Bei der Nullintervention wurde keine Nadel gesetzt. Bei jeder Intervention wurden jeweils vorher und nachher Parameter der Herzratenvariabilität (HRV) ermittelt. Ergebnisse: Zwischen den drei Interventionen konnten keine signifikanten Unterschiede der HRV-Parameter festgestellt werden. Zwischen Baseline- und Endmessung sank die Herzfrequenz bei der Kontroll- und Prüfintervention (-2 min^-1, d = 0,24 bzw. -2 min^-1, d = 0,24), die RMSSD stieg mit der Nadelberührung bzw. der Stimulation des Qi signifikant an (+9.7 ms, d = -0.32). Schlussfolgerung: Die zuvor subjektiv wahrgenommene Stimulation mit therapeutischem Qi konnte innerhalb dieses Settings anhand von HRV-Parametern nicht ausreichend bestätigt werden.

Acute effect of zoledronic acid on the risk of cardiac dysrhythmias.

There have been recent concerns regarding the risk of serious adverse events, such as cardiac dysrhythmia and atrial fibrillation (AF), associated with bisphosphonate use in osteoporosis. This open-label, non-randomized, crossover pilot study evaluated short-term effects of zoledronic acid and placebo on the occurrence of cardiac dysrhythmias and prodysrhythmic profile in postmenopausal women with osteoporosis and low risk of cardiac dysrhythmias. Fifteen postmenopausal women (mean age 70.7 ± 6.9 years) with osteoporosis received placebo infusion on day 1 and zoledronic acid 5 mg on day 7. Standard 12-lead resting EKG measured QT parameters at baseline and up to 24 h after infusion. Continuous 24-h EKG assessed dysrhythmic events and heart rate variability (HRV) for 24 h after infusion. There were no statistically significant differences in resting EKG parameters between placebo and zoledronic acid: QTc (404.28 ± 9.28 and 410.63 ± 18.43 ms), no significant differences in mean serum electrolytes at baseline and after infusion, and no significant association between QT/QTc parameters and serum electrolytes before and after each infusion (QTc: 401.83 ± 17.73 for zoledronic acid and 404.65 ± 16.79 for placebo). There was no significant difference in HRV parameters between placebo and zoledronic acid, and no dysrhythmias were recorded at rest or with 24 h EKG monitoring. Zoledronic acid does not produce dysrhythmia or prodysrhythmic effects in the short term. Among possible mechanisms proposed for cardiac dysrhythmias with zoledronic acid, no serum electrolyte or autonomous nervous system balance perturbations have been reported.

Normal values for heart rate variability parameters in children 6–8 years of age: the PANIC Study

Measurement of heart rate variability (HRV) is a useful method for examining cardiac autonomic control. HRV has been measured in many studies among adults, but research on this topic among children is limited. We therefore defined reference values for a large number of HRV parameters among children. The subjects were a population sample of 465 mainly prepubertal children 6-8years of age. Electrocardiogram (ECG) was recorded at rest, and 1- and 5-min ECG samples were selected for HRV analyses. HRV data were analysed in boys and girls separately to study possible gender differences in HRV parameters. Pearson's coefficients for correlation of age, maturity stage, height, weight and body mass index - standard deviation score (BMI-SDS) with HRV parameters were computed to study whether these factors confounded the definition of the reference values for HRV parameters. We found no statistically significant differences in HRV parameters between genders. Therefore, we defined the reference values for all HRV parameters as 5th, 25th, 50th, 75th and 95th percentiles from the ECG samples in all children, but not in boys and girls separately. Age, maturity stage, height, weight and BMI-SDS had weak, if any, associations with HRV parameters, suggesting that they did not confound the definition of the reference values. Same reference values for HRV parameters can be used in boys and girls. Although 5-min ECG recordings are preferable for measuring HRV, also 1-min recordings provide reliable data on most HRV parameters, especially those that mainly describe cardiac parasympathetic regulation.

Cardiac autonomic function and cardiac arrhythmias in patients with obstructive sleep apnea

We assessed the effect of obstructive sleep apnea syndrome (OSAS) on cardiac autonomic function with the parameters of heart rate variability (HRV) and heart rate turbulence (HRT) and investigated the frequency of cardiac arrhythmias in patients with OSAS. Seventy-six patients (27 women, 49 men; mean age 50.6±10.7 years; range 33 to 75 years) with an initial diagnosis of OSAS underwent polysomnography and simultaneous Holter monitoring. The diagnosis of OSAS was based on an apnea-hypopnea index (AHI) of ≥5. The patients were evaluated with time-and frequency-based parameters of HRV, and turbulence onset (TO) and turbulence slope (TS) parameters of HRT. Cardiac arrhythmias were also assessed on Holter monitoring. Fifty-three patients (69.7%) were diagnosed with OSAS, being mild in 25 (47.2%), moderate in 23 (43.4%), and severe in five (9.4%) patients based on the AHI. The patients were divided into two groups as those having an AHI of <5 (n=23) and ≥5 (n=53). There were no significant differences in HRV parameters between the two groups, but patients with OSAS exhibited a significantly higher TO (p=0.02) and a significantly lower TS (p<0.001). In bivariate correlation analysis, AHI showed a significant negative correlation with TS (r=-0.37, p=0.009) and a significant positive correlation with TO (r=0.36, p=0.01). The frequencies of short-sequence premature atrial and ventricular contractions were significantly higher in patients with OSAS (p<0.001). Our findings suggest that blunting of HRT is more prominent than changes in HRV parameters in patients with OSAS, accompanied by increased frequency of cardiac arrhythmias.

Quantitative analysis of heart rate variability in patients with absence epilepsy

There are no studies quantifying the nature of autonomic changes in absence epilepsy. Aims : We characterized the heart rate variability (HRV) during pre-interictal epileptiform discharges (IED), IED and post-IED states in absence epilepsy. Electroencephalogram (EEG) records with generalized 3-Hz spike-wave discharges in 8 patients (M: F: 3 : 5; mean age: 13.0 ± 2.5 years) with absence epilepsy were identified and corresponding electrocardiogram (ECG) time series were obtained. The time domain HRV measures were applied to pre-IED, IED and post-IED simultaneous ECG tracing. There was slight tachycardia during the IED phase (pre-IED: 90.15 ± 3.45 bpm, IED: 94.82 ± 4.63 bpm, P = 0.09) which returned to baseline during the post-IED phase (post-IED: 89.65 ± 3.78 bpm). There was significant decrease in the standard deviation of RR interval (pre-IED: 40.0 ± 4.15 ms, IED: 30.4 ± 4.19 ms, P = 0.032) and trend in reduction of triangular index (pre-IED: 0.05 ± 0.01, IED: 0.04 ± 0.004, P = 0.08) during the IED phase when compared to pre-IED phase. The percentage of RR intervals >50 ms was lower during the IED phase and achieved significance when compared to post-IED phase (IED: 10.08 ± 4.89, post-IED: 18.74 ± 6.17, P = 0.050). While mean HR and RR interval significantly correlated with the duration of IEDs, there was no significant correlation between its duration with change in HRV parameters between the groups. There was no significant difference in HRV parameters between patients with long (>10s) and short (<10s) duration of IED. Transient increase in heart rate during IED phase was noted in patients with absence epilepsy. Longer duration of IED seems to be linked with significant tachycardia. While most HRV parameters did not reach statistical significance, standard deviation of RR intervals and triangular index was noted to be decreased during the IED phase and returns to pre-IED levels after the episode.

Heart rate variability in familial Mediterranean fever

Familial Mediterranean fever (FMF) is a hereditary disease, characterized by recurrent episodes of fever and polyserositis. Heart rate variability (HRV) is a powerful, simple and reliable technique to evaluate autonomic nervous system function. Previous studies of physiologic parameters during tilt-test have suggested that patients with FMF have abnormal cardiovascular reactivity and occult dysautonomia. Prompted by these findings, the present study sought to evaluate HRV in patients with FMF, at rest and in the standing position. The study sample included 34 patients with FMF and 34 sex- and age-matched control subjects. All underwent electrocardiography according to strict criteria. HRV parameters were computed with custom-made software. There was no significant difference in HRV parameters, in either the supine or standing position, between the FMF and control groups. In both groups, the upright position was associated with a significant decrease, when compared with the supine position, in maximal RR interval, minimal RR, average RR, root square of successive differences in RR interval, number of intervals differing by >50 ms from preceding interval (NN50), NN50 divided by total number of intervals (pNN50) and high-frequency components as well as a significant increase in average heart rate, very low frequency or low-frequency components, low-frequency/high-frequency components ratio and total power. In conclusion, patients with FMF who are continuously treated with low-dose colchicine have not developed amyloidosis and have normal HRV parameters in the supine and upright position. Further investigation of occult dysautonomia in FMF is needed.