Frequency-domain Analysis Of Heart Rate Variability Research Articles

Short-term heart rate variability as a predictor of long-term survival in patients with chronic hemodialysis: A prospective cohort study.

Heart rate variability (HRV), a non-invasive measurement of the sympathetic-vagal balance, has been demonstrated as a predictor of long-term survival in various patient populations. However, its predictive value in patients with end-stage renal disease (ESRD) has not been evaluated in a long-term follow-up study. Prospective data collected for 41 patients with chronic hemodialysis (age 59±10 years, men 51.3%, diabetes mellitus 31%, and duration of dialysis 64±50 months) who underwent a 5-minute electrocardiogram (ECG) recording as a baseline for frequency domain HRV analysis. During a median follow-up of 150.2 months from 2003 to 2014, 15 (35.7%) patients died (3 due to cardiac causes and 12 due to non-cardiac causes). The Cox proportional hazards model suggested that the low frequency versus high frequency signal (LF/HF) of a high ratio for the HRV and diabetes mellitus were two independent predictors of mortality (hazard ratios 3.028 and 3.494; p=0.033 and 0.022, respectively). Less reduction in MAP during dialysis showed borderline significance of long-term survival than those with larger drop (p=0.058). A short ECG recording and an analysis of the frequency domain of the HRV is clinically predictive of the long-term survival of patients with chronic hemodialysis.

Heart rate variability is associated with outcome in spontaneous intracerebral hemorrhage

PurposeAutonomic imbalance as measured by heart rate variability (HRV) has been associated with poor outcome after stroke. Observations on HRV changes in intracerebral hemorrhage (ICH) are scarce. Here, we aimed to investigate HRV in ICH as compared to a control group and to explore associations with stroke severity, hemorrhage volume and outcome after ICH. MethodsWe examined the autonomic modulation using frequency domain analysis of HRV during the acute phase of the ICH and in a healthy age- and hypertension-matched control group. Hematoma volume, intraventricular extension, initial stroke severity and baseline demographic, clinical parameters as well as mortality and functional outcome were included in the analysis. Results47 patients with ICH and 47 age- and hypertension matched controls were analyzed. ICH patients showed significantly lower total high frequency band (HF) and low frequency band (LF) powers (p = 0.01, p < 0.001), higher normalized HF power (p = 0.03), and lower LF/HF ratio (p < 0.001) as compared to the controls. Autonomic parameters showed associations with stroke severity (p = 0.004) and intraventricular involvement (p = 0.01) and predicted poor outcome independently (p = 0.02). ConclusionsAutonomic changes seems to be present in acute ICH and are associated with poor outcome independently. This may have future monitoring and therapeutic implications.

Badanie przesiewowe pacjentów z chorobą wieńcową w kierunku obturacyjnego bezdechu sennego i ocena jego wpływu na zmienność rytmu zatokowego

Introduction. Obstructive sleep apnea (OSA) is one of the most common sleep disorders, which affects 4% of men and 2% of women in the world population. The disorder can be diagnosed in men and women of all ages; however, its incidence increases with age. Patients with OSA experience increased levels of sympathetic nervous system activity, which is evidenced by the increased catecholamines secretion. They are at an increased risk of developing complications of coronary heart disease (CHD). The aim of the study was to evaluate the influence of results of screening for OSA on the activity of the sympathetic and parasympathetic nervous systems within the scope of selected heart rate variability (HRV) parameters (time-domain and frequency-domain analyses of the HRV) in patients with CHD. Material and methods. Holter recordings of 146 patients aged 43–78 (106 of whom were men) were analysed retrospectively. The patients were divided into four groups on the basis of the estimated apnea–hypopnea index (eAHI), assessed by means of 24-hour recordings of electrocardiogram with Lifescreen Apnea software: &lt; 5 (control group), from 5 to &lt; 15 (mild), from 15 to &lt; 30 (moderate) and ≥ 30 episodes (severe). For each patient, a profile of power spectrum alterations was developed for low frequency (LF) and high frequency (HF) in 60-minute periods between 10 p.m. and 6 a.m. and standard deviation of RR intervals (SDNN) and root mean square of successive differences (rMSSD) values were calculated. The power spectrum in the consecutive one-hour periods was averaged in both groups. In view of the right-skewed distribution of data, the average power spectra were converted into natural logarithms. In order to assess the significance of variations, the natural logarithms of the average values were compared using the univariate analysis of variance (ANOVA). Results. In the examined groups, there were statistically significant differences in the HF band of power spectrum between the control group and the group of patients with mild OSA (p &lt; 0.01), those with severe OSA (p &lt; 0.01) and also between the group with mild and moderate OSA (p &lt; 0.01). In the LF band of power spectrum, the only difference was seen between the group of patients with mild OSA and those with moderate OSA (p &lt; 0.01). In the time-domain analysis of HRV (SDNN, rMSSD), no statistically significant differences between the groups were observed. Conclusions. High frequency band of power spectrum [HF] in frequency-domain HRV analysis could be a more effective parameter to distinguish patients with mild OSA (from 5 to &lt; 15) and severe OSA (≥ 30) in patients suffering from CHD, than the power spectrum for LF or SDNN and rMSSD.

Deceleration capacity-a novel measure for autonomic nervous system in patients with vasovagal syncope on tilt-table testing.

This study was to investigate the changes of autonomic nerve function and hemodynamics in patients with vasovagal syncope (VVS) during head-up tilt-table testing (HUT). HUT was performed in 68 patients with unexplained syncope and 18 healthy subjects served as control group. According to whether bradycardia, hypotension or both took place during the onset of syncope, the patients were divided during the test into three subgroups: vasodepressor syncope (VD), cardioinhibitory syncope (CI) and mixed syncope (MX) subgroups. Heart rate, blood pressure, heart rate variability (HRV), and deceleration capacity (DC) were continuously analyzed during HUT. For all the subjects with positive responses, the normalized low frequency (LFn) and the LF/HF ratio markedly decreased whereas normalized high frequency (HFn) increased when syncope occurred. Syncopal period also caused more significant increase in the power of the DC in positive groups. These changes were more exaggerated compared to controls. All the patients were indicative of a sympathetic surge in the presence of withdrawal vagal activity before syncope and a sympathetic inhibition with a vagal predominance at the syncopal stage by the frequency-domain analysis of HRV. With the measurements of DC, a decreased vagal tone before syncope stage and a vagal activation at the syncopal stage were observed. The vagal tone was higher in subjects showing cardioinhibitory responses at the syncopal stage. DC may provide an alternative method to understand the autonomic profile of VVS patients.

Compression at Myofascial Trigger Point on Chronic Neck Pain Provides Pain Relief through the Prefrontal Cortex and Autonomic Nervous System: A Pilot Study.

Compression at myofascial trigger points (MTrPs), known as “ischemic compression,” has been reported to provide immediate relief of musculoskeletal pain and reduce the sympathetic activity that exacerbates chronic pain. We conducted a pilot study to investigate the possible involvement of the prefrontal cortex in pain relief obtained by MTrP compression in the present study, and analyzed the relationships among prefrontal hemodynamic activity, activity of the autonomic nervous system, and subjective pain in patients with chronic neck pain, with and without MTrP compression. Twenty-one female subjects with chronic neck pain were randomly assigned to two groups: MTrP compression (n = 11) or Non-MTrP compression (n = 10). Compression for 30 s was conducted 4 times. During the experiment, prefrontal hemodynamic activity [changes in Oxy-hemoglobin (Hb), Deoxy-Hb, and Total-Hb concentrations] and autonomic activity based on heart rate variability (HRV) were monitored by using near infrared spectroscopy (NIRS) and electrocardiography (ECG), respectively. The results indicated that MTrP compression significantly reduced subjective pain compared with Non-MTrP compression. The spectral frequency-domain analyses of HRV indicated that a low frequency (LF) component of HRV was decreased, and a high frequency (HF) component of HRV was increased during MTrP compression, while LF/HF ratio was decreased during MTrP compression. In addition, prefrontal hemodynamic activity was significantly decreased during MTrP compression compared with Non-MTrP compression. Furthermore, changes in autonomic activity were significantly correlated with changes in subjective pain and prefrontal hemodynamic activity. Along with previous studies indicating a role for sympathetic activity in the exacerbation of chronic pain, the present results suggest that MTrP compression in the neck region alters the activity of the autonomic nervous system via the prefrontal cortex to reduce subjective pain.

Can coefficient of variation of time-domain analysis be valuable for detecting cardiovascular autonomic neuropathy in young patients with type 1 diabetes: a case control study

BackgroundCardiovascular autonomic neuropathy (CAN) increases morbidity and mortality in diabetes through association with a high risk of cardiac arrhythmias and sudden death, possibly related to silent myocardial ischemia. During the sub-clinical stage, CAN can be detected through reduction in heart rate variability (HRV). The aim of our study was to estimate if the time and frequency-domain analysis can be valuable for detecting CAN in young patients with type 1 diabetes mellitus (T1DM).MethodsFor this case control study of evaluation of cardiovascular autonomic function the 15–25 years age group of patients with duration of T1DM more than 9 years (n = 208, 89 males and 119 females) were selected. 67 patients with confirmed CAN were assigned to the “case group” and 141 patients without CAN served as a control group, the duration of T1DM was similar (15.07 ± 4.89 years vs.13.66 ± 4.02 years; p = 0.06) in both groups. Cardiovascular autonomic reflex tests and time and frequency domains analysis of HRV were performed for all subjects.ResultsTime domain measures were significantly lower in CAN group compared with control (p < 0.05). R-R max / R-R min ratio and coefficient of variation (CV) were the lowest during deep breathing among T1DM patients with CAN. Receivers operating characteristic (ROC) curves were constructed to compare the accuracies of the parameters of time-domain analysis for diagnosing CAN. We estimated a more reliable cut-off value of parameters of time-domain. The CV values in supine position <1.65, reflected sensitivity 94.3%, specificity 91.5%. The CV values during deep breathing <1.45 reflected sensitivity 97.3%, specificity 96.2%. The CV values in standing position <1.50 reflected sensitivity 96.2%, specificity 93.0%. The most valuable CV was during deep breathing (AUC 0.899). The results of frequency-domain (spectral analysis) analysis showed significant decrease in LF power and LFPA, HF Power and HFPA, total power among subjects with CAN than compared with subjects without CAN (p < 0.05).ConclusionsTime and frequency domain analysis of HRV permits a more accurate evaluation of cardiovascular autonomic function, providing more information about sympathetic and parasympathetic activity. The coefficient of variation (time-domain analysis) especially during deep breathing could be valuable for detecting CAN.

Assessment of Autonomic Dysfunction in Acute Stroke Patients at a Tertiary Care Hospital.

In patients who present with acute cerebro-vascular disease, autonomic function testing is usually not given its due importance. This is because of the complex nature of the autonomic function tests and the relative technical difficulty faced in administering the tests to the patients. A simple and non-invasive method to assess the autonomic dysfunction is measurement of resting Heart Rate Variability (HRV). To study the pattern of autonomic dysfunction among patients admitted with acute stroke and to study the relationship between autonomic dysfunction and the morbidity and mortality associated with acute stroke. The study was carried out on 97 patients who were admitted with diagnosis of acute stroke. Patients with conduction abnormalities on ECG were excluded from the study. Resting ECG tracings were obtained for a period of 5 minutes. The frequency domain analysis of HRV was performed by a Fast Fourier transform of the RR intervals. The High Frequency (HF) was representative of the parasympathetic activity while low frequency is representative of baroreceptor mediated parasympathetic and sympathetic activity and Low Frequency (LF)/HF ratio was a measure of the sympathovagal balance. Statistical analysis was carried out with student's t-test and chi-square test and p-value ≥ 0.05 was taken to be statistically significant. The mean age of the patients was 60.84±14.12 years. A total of 41 patients were females and 77 patients had ischemic stroke. Out of the total 97, 60 patients had evidence suggestive of increased sympathetic activity with a mean LF/HF ratio of 2.03±0.88. These patients had significantly higher mean systolic BP, diastolic BP and National Institute of Health Stroke Scale (NIHSS) values when compared to patients with reduced LF/HF ratio (166.33±24.81 vs 148.54±19.42, p=0.0003, 100.33±18.73 vs 88.76±12.66, p=0.0013, 15.77±8.22 vs 11.49±6.63, p=0.0088 respectively). These patients also had a higher mortality rate. This study highlights the problem of autonomic dysfunction among patients with stroke. Patients with autonomic dysfunction had higher morbidity and mortality in the acute phase of stroke in this study and also had higher blood pressure readings. This is a small scale study whose findings need to be validated further by larger population studies.

Predicting depressed patients with suicidal ideation from ECG recordings.

Globally suicidal behavior is the third most common cause of death among patients with major depressive disorder (MDD). This study presents multi-lag tone-entropy (T-E) analysis of heart rate variability (HRV) as a screening tool for identifying MDD patients with suicidal ideation. Sixty-one ECG recordings (10min) were acquired and analyzed from control subjects (29 CONT), 16 MDD subjects with (MDDSI+) and 16 without suicidal ideation (MDDSI-). After ECG preprocessing, tone and entropy values were calculated for multiple lags (m: 1-10). The MDDSI+ group was found to have a higher mean tone value compared to that of the MDDSI- group for lags 1-8, whereas the mean entropy value was lower in MDDSI+ than that in CONT group at all lags (1-10). Leave-one-out cross-validation tests, using a classification and regression tree (CART), obtained 94.83% accuracy in predicting MDDSI+ subjects by using a combination of tone and entropy values at all lags and including demographic factors (age, BMI and waist circumference) compared to results with time and frequency domain HRV analysis. The results of this pilot study demonstrate the usefulness of multi-lag T-E analysis in identifying MDD patients with suicidal ideation and highlight the change in autonomic nervous system modulation of the heart rate associated with depression and suicidal ideation.

Reduced power spectra of heart rate variability are correlated with anxiety in patients with mild traumatic brain injury

Anxiety is one of the most frequently diagnosed emotional disorders after a mild traumatic brain injury (mTBI); however, predictors of anxiety after an mTBI remain uncertain. Recent research indicated that anxiety is associated with abnormalities in the autonomic nervous system (ANS) which can be evaluated by a power spectral analysis of heart rate variability (HRV). In this study, we investigated whether a frequency-domain analysis of HRV could correlate with the occurrence of anxiety in mTBI patients. We recruited 165 Taiwanese patients diagnosed with an mTBI and 82 volunteer healthy controls from three affiliated hospitals of Taipei Medical University during 2010–2014. The Beck Anxiety Inventory (BAI) was assessed at the 1st, 6th, and 12th weeks. We found that mTBI patients were more vulnerable to anxiety compared to healthy controls. The power spectral density of HRV was significantly lower in mTBI patients than in healthy controls. A correlation analysis indicated that anxiety was negatively significantly correlated with low- and high-frequency power at the 6th week. Our study suggests the clinical usefulness of HRV as a potential noninvasive tool for evaluating later anxiety in mTBI patients.

Assessment of Time and Frequency Domain Parameters of Heart Rate Variability and Interictal Cardiac Rhythm Abnormalities in Drug-naïve Patients with Idiopathic Generalized Epilepsy.

Background and Purpose:Epilepsy is a disease known to occur with autonomous phenomenons. Earlier studies indicate decreased heart rate variability (HRV) during ictal and interictal periods among epilepsy patients. In this study, we aim to investigate cardiac rhythm abnormalities and HRV during interictal period between drug-naïve patients with idiopathic generalized epilepsy (IGE) and healthy control group.Methods:Twenty-six patients with IGE and 26 healthy individuals included in the study. In order to eliminate any structural cardiac pathology, transthoracic echocardiography was performed in all subjects and time and frequency domain parameters of HRV were evaluated after 24-hour rhythm holter monitoring.Results:Between two groups, no significant difference was detected in terms of mean heart rate and maximum duration between the start of the Q waves and the end of the T waves (QT intervals). In the time domain analysis of HRV, no statically significant difference was detected for standard deviation of all R - R intervals and root-mean-square of successive differences between patient and control group (p = 0,070 and p = 0,104 respectively). In the frequency domain analysis of HRV, patients tended to display lower total power and very low frequency power than did healthy subjects, but the differences were not statistically significant.Conclusions:Our results suggest that there is no major effect of the epilepsy on HRV in patients with IGE. It should be emphasized that, in this study, HRV was evaluated only in patients with IGE and that the results are not proper to be generalized for patients with partial seizures.

Bariatric Surgery Restores Cardiac and Sudomotor Autonomic C-Fiber Dysfunction towards Normal in Obese Subjects with Type 2 Diabetes.

ObjectiveThe aim was to evaluate the impact of bariatric surgery on cardiac and sudomotor autonomic C-fiber function in obese subjects with and without Type 2 diabetes mellitus (T2DM), using sudorimetry and heart rate variability (HRV) analysis.MethodPatients were evaluated at baseline, 4, 12 and 24 weeks after vertical sleeve gastrectomy or Roux-en-Y gastric bypass. All subjects were assessed using SudoscanTM to measure electrochemical skin conductance (ESC) of hands and feet, time and frequency domain analysis of HRV, Neurologic Impairment Scores of lower legs (NIS-LL), quantitative sensory tests (QST) and sural nerve conduction studies.ResultsSeventy subjects completed up to 24-weeks of follow-up (24 non-T2DM, 29 pre-DM and 17 T2DM). ESC of feet improved significantly towards normal in T2DM subjects (Baseline = 56.71±3.98 vs 12-weeks = 62.69±3.71 vs 24-weeks = 70.13±2.88, p<0.005). HRV improved significantly in T2DM subjects (Baseline sdNN (sample difference of the beat to beat (NN) variability) = 32.53±4.28 vs 12-weeks = 44.94±4.18 vs 24-weeks = 49.71±5.19, p<0,001 and baseline rmsSD (root mean square of the difference of successive R-R intervals) = 23.88±4.67 vs 12-weeks = 38.06±5.39 vs 24-weeks = 43.0±6.25, p<0.0005). Basal heart rate (HR) improved significantly in all groups, as did weight, body mass index (BMI), percent body fat, waist circumference and high-density lipoprotein (HDL). Glycated hemoglobin (HbA1C), insulin and HOMA2-IR (homeostatic model assessment) levels improved significantly in pre-DM and T2DM subjects. On multiple linear regression analysis, feet ESC improvement was independently associated with A1C, insulin and HOMA2-IR levels at baseline, and improvement in A1C at 24 weeks, after adjusting for age, gender and ethnicity. Sudomotor function improvement was not associated with baseline weight, BMI, % body fat or lipid levels. Improvement in basal HR was also independently associated with A1C, insulin and HOMA2-IR levels at baseline.ConclusionThis study shows that bariatric surgery can restore both cardiac and sudomotor autonomic C-fiber dysfunction in subjects with diabetes, potentially impacting morbidity and mortality.

Investigation of heart rate variability in major depression patients using wavelet packet transform

Studies conducted in major depression (MD) patients have reported a high risk of cardiac morbidity as a result of the relationship between changed cardiovascular activity (CA) and autonomic dysfunctions. The investigation of heart rate variability (HRV) gives valuable idea about variances in autonomic CA of MD patients. To get this knowledge, frequency-domain HRV analysis is frequently performed using Fourier transformation (FT) or discrete-wavelet transformation (DWT) to decompose the data into high-frequency (HF) and low-frequency (LF) bands. Nevertheless, it has been reported that the FT is not useful for nonstationary HRV signals and the DWT does not ensure required frequency boundaries of each band. This study aims to compare the frequency-domain HRV features using wavelet-packet-transform (WPT) with absolutely excellent approximation to required band ranges between the controls and patients. In addition to LF and HF band energies, sympathovagal balance that indicates the variation of sympathetic and parasympathetic activities were compared between two groups. Patients had a significantly lower HF energy, higher values of LF energy and higher LF/HF ratio. Our results recommend that impairments in coordination between parasympathetic and sympathetic behavior in MD patients can be assessed by HRV analysis using WPT with high resolution decomposition for needed bands.

Early dysautonomia detected by heart rate variability predicts late depression in female patients following mild traumatic brain injury

Depression is one of the frequent complications following a mild traumatic brain injury (mTBI). Recent research indicated that abnormalities in the autonomic nervous system (ANS) can be evaluated by a noninvasive power spectral analysis of the heart rate variability (HRV). In this study, we investigated whether a frequency-domain analysis of HRV was correlated with late depression in mTBI patients. In total, 181 patients diagnosed with mTBI and 83 volunteers as healthy controls were recruited in 2010-2014. Beck Depression Inventory (BDI) scores were used to evaluate depression in the 1st week of assessment and at 1.5-, 3-, 6-, 12-, and 18-month follow-ups. Correlation and logistic regression analyses of the 1st week HRV parameters with BDI scores at 18 months were performed in individual female mTBI patients. Female mTBI patients were more vulnerable to depression accompanied by reduced HRV compared to healthy controls. Over time, depression was aggravated in female mTBI patients but was alleviated in male mTBI patients. A significantly lower parasympathetic proportion of the ANS was noted at 18 months with respect to the 1st week in female mTBI patients. In addition, depression in female mTBI patients at 18 months after injury was significantly correlated with a decrease in the parasympathetic proportion of the ANS in the 1st week (ρ = -0.411; p < .05). Dysautonomia resulted in higher risks of depression in female mTBI patients. We concluded that early dysautonomia following an mTBI contributes to late depression in female mTBI patients.

THE RECENT USE OF HEART RATE VARIABILITY FOR RESEARCH

Heart rate variability (HRV) is a non-invasive method that analysis cardiac autonomic regulation1,2.The use of this method was previously validated in physiological experiments3,4,which performed pharmacological stimulation of the sympathetic and parasympathetic nervous systems and made relationship with the traditional time and frequency domain analysis of HRV, confirming the use of this method to evaluate cardiac autonomic regulation. Moreover, HRV has also been used to predict mortality after cardiacevents5 and it has been considered as a marker of stress6. An easy and economic access to HRV analysis through heart rate monitors, which are well recognized in the literature7, 8 helped researches to use this method to evaluate cardiac autonomic regulation.In the last 15 years this method has received great attention.After a careful search on Pubmed/Medline, the term “heart rate variability” was present in 1,013 manuscripts in 2014, in 2013 this number was 972 and in 2012 it was 7299. We realize that each year the number of groups that use HRV in their studies has considerably increased. In this context, I raise points that are worth to mention. Firstly, advantages includeadditional information for cardiac autonomic responses in pathological situations10-12, during physiological stress13,14, association with social function15 for instance. It is currently clear that autonomic nervous system is related to several conditions. Nevertheless, before starting to study HRV analysis,relevant details of this method should be discussed in order to avoid misunderstanding of results. For example, HRV consider the interval between consecutive heart beats2, reflecting parasympathetic and sympathetic cardiac autonomic modulation, it does not directly measures sympathetic or parasympathetic activity. There are different methods that quantify it, i.e. plasma levels of norepinephrine and epinephrine16, renal sympathetic nerve activity17and parasympathetic nerve activity18. In 1996, the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology published methodological considerations regarding traditional time and frequency domain analysis of HRV2. This seminal publication aimed to permit appropriate comparisons.Since then, new methods related to the chaos theory applied on organic systems and heart rate dynamics has been investigated19. This year the European Society of Cardiology together with the European Heart Rhythm Association and co-endorsed by the Asia Pacific Heart Rhythm Society reviewed the literature abovementioned in 199619. They addressed the use of non-conventional methods (nonlinear) which had been used in a significant number of patients (more than 200 cases) finding only 21 studies from the thousands already published. They described in details nonlinear methods as Detrended fluctuation analysis with a1 and a2 components, Hurst Exponent, Correlation Dimension and Largest Lyapunov Exponent. In this sense, I take this opportunity to reinforce attention of researchers around the world to keep being extremely careful when using HRV for their analysis. Important factors are necessary to consider, such as sample frequency to use when digitalizing the electrocardiogram, filtering records, caution with stationary data andwhether to interpolate an electrocardiogram to enhance accuracy of R wave. Therefore, investigators around the world will keep helping us to discover the unlimited mysteries of science. The current number of the Journal of Human Growth and Development is composed by a total of 15 original manuscripts. The journal keeps

&lt;b&gt;Increase in perceived stress is correlated to lower heart rate variability in healthy young subjects

Emotional stress is a risk factor for cardiovascular disease. Decreased heart rate variability (HRV) is associated to increased mortality rates in certain heart diseases. Current study assessed the co-relation between perceived stress and HRV parameters. The correlation between psychological stress, measured by the perceived stress scale (PSS-14), and HRV parameters obtained during 5 min. at rest was evaluated. Data from 35 healthy young volunteers demonstrated a significant correlation between PSS-14 scores and Low Frequency-LF (ms 2 ) by frequency domain HRV analysis. Other variables such as High Frequency and Standard Deviation of R-R intervals had also negative coefficients but did not have any significant correlation with PSS-14. No correlation between PSS-14 and sympathovagal balance parameters was found. Data interpretation demonstrated that increase in perceived stress was correlated to decrease in heart rate variability, which may point out an important mechanism in cardiovascular pathophysiology that should be further investigated.

Changes of Heart Rate Variability during Methylphenidate Treatment in Attention-Deficit Hyperactivity Disorder Children: A 12-Week Prospective Study.

PurposeThe aim of this study was to clarify the relationship between the autonomic nervous system and attention deficit hyperactivity disorder (ADHD) rating scales and to evaluate the usefulness of heart rate variability (HRV) as a psychophysiological biomarker for ADHD.Materials and MethodsSubjects were recruited from outpatients in the Department of Child and Adolescent Psychiatry at the Korea University Medical Center from August 2007 to December 2010. Subjects received methylphenidate. Time- and frequency-domain analyses of HRV, the Korean ADHD rating scale (K-ARS), and computerized ADHD diagnostic system were evaluated before treatment. After a 12-week period of medication administration, we repeated the HRV measurements and K-ARS rating.ResultsEighty-six subjects were initially enrolled and 37 participants completed the 12-week treatment and HRV measurements subsequent to the treatment. Significant correlations were found between the K-ARS inattention score and some HRV parameters. All of the HRV parameters, except the standard deviations of the normal-to-normal interval, very low frequency, and low frequency to high frequency, showed a significant positive correlation between baseline and endpoint measures in completers. High frequency (HF) and the square root of the mean squared differences of successive normal-to-normal intervals (RMSSD), which are related to parasympathetic vagal tone, showed significant decreases from baseline to endpoint.ConclusionThe HRV test was shown to be reproducible. The decrease in HF and RMSSD suggests that parasympathetic dominance in ADHD can be altered by methylphenidate treatment. It also shows the possibility that HRV parameters can be used as psychophysiological markers in the treatment of ADHD.

Autonomic dysfunction: a driving force for myocardial fibrosis in young Duchenne muscular dystrophy patients?

Cardiac manifestations of Duchenne muscular dystrophy (DMD) include progressive cardiac dysfunction and an elevated resting heart rate (HR). We hypothesized this elevated HR reflects autonomic dysfunction that can be identified by heart rate variability (HRV) analyses which will be associated with myocardial fibrosis by cardiac magnetic resonance imaging (cMR). DMD patients (N=74) and controls (N=17) had time and frequency domain HRV analyses calculated via Holter monitoring. Cardiac magnetic resonance imaging was performed on DMD cases only. χ (2) test, T test, ANOVA, and logistic regression were used to perform comparisons between groups. A p value of <0.05 was used for statistical significance. DMD cases had higher resting average HR than controls (99.4±8.9, 85.4+6.2, p<0.001). Among HRV variables, decreases were seen in the following: standard deviation of R to R intervals, the percent RR intervals differing by >50ms from previous RR interval, the root-meansquare of successive differences of RR intervals, the standard deviation of the mean R to R segment (SDANN), low frequency, and high frequency domain, all p values 0.001. Maximum HR and SDANN most significantly associated with positive LGE on cMR (p=0.008, p=0.016). DMD cases on beta blocker had an average HR lower than those not on beta blocker (p=0.009), but with no difference in HRV analysis. DMD patients have reduced HRV and therefore autonomic dysfunction prior to the onset of heart failure which is associated with myocardial fibrosis.

ACUTE EFFECTS OF ALCOHOL ON HEART RATE VARIABILITY: TIME-RELATED CHANGES AND GENDER DIFFERENCE

Objectives: Alcohol consumption is associated with a broad array of physiologic and behavioral effects including changes in cardiac autonomic activity. In the present study, time-related acute effects of alcohol have been characterized and compared between genders. Methods: A total of 30 healthy subjects (15 males and 15 females) were enrolled in this study. The red wine was given to each subject at a dosage of 0.27 g of pure ethanol per kilogram of body weight. 5-min electrocardiograms (ECGs) were collected before (BR) and at 15 min (P15), 30 min (P30), 45 min (P45) and 60 min (P60) after alcohol intake. Time- and frequency-domain analysis of heart rate variability (HRV) was performed. The time-domain HRV indices include mean RR interval, pNN50, SDNN and RMSSD. The low- (LF: 0.04 to 0.15 Hz) and high-frequency (HF: 0.15 to 0.4 Hz) components along with LF/HF ratio were calculated for frequency-domain analysis of HRV. HRV was also analyzed by mathematical models, e.g. Poincaré plot, which uses a nonlinear geometric representation of change in interbeat heart rate. Poincaré plots indices, SD1, SD2, SD1/SD2 ratio and r RR , were applied in this study for HRV assessment. Results: Alcohol intake was associated with decreased HRV in both time and frequency domains. The lowest HRV was observed 30–40 min after the intake of alcohol. The alcohol intake also caused the decrease of Poincaré plots indices (SD1 and SD1/SD2 in P30, P40 and P60, and r RR in P45), accompanied with a narrower plot area. The changes of HRV indices differed by gender. The male subjects demonstrated a greater decrease of parameters measured in this study compared to the female subjects. Conclusion: Acute effects of alcohol ingestion resulted in reductions in HRV, indicating impaired cardiac autonomic nervous activity. Autonomic nervous activity in the females was less dampened by the alcohol compared to the males.

Autonomic Dysfunction in Asian Indian T2DM Patients is Related to Body Fat Content Instead of Insulin Resistance: A DEXA Study

Aim: To study autonomic dysfunction in Asian Indian T2DM patients by heart rate variability and it's relation with body fat content, distribution and insulin resistance.Subjects and Methods: Subjects: 33 T2DM patients aged (46.96 ± 8.90 yrs), and 33 healthy controls aged (44.08 ± 9.15 yrs).Methods: Short-term heart rate variability (HRV) was measured by impedance plethysmograph recording of pulse wave in distal superficial arteries. Time domain and Frequency domain analysis of HRV was carried out. Time domain parameters (SDNN, rMSSD, pNN50) and frequency domain parameters (Total Power, LF power, HF Power, LF (nu), HF (nu), LF/HF Ratio) were determined. Body fat content and distribution was estimated by (DEXA). Insulin Resistance was assessed by HOMA-R. Student t test was used for comparison of parameters in two groups. Multiple regression was used to find out relation between parameters of adiposity and HRV.Results: Parameters rMSSD, pNN50, Total power, LF Power, HF Power were significantly lower in diabetics. Total power showed negative correlation with BMI and truncal fat (r=-.43; p

Comparison of heart rate variability response in children undergoing elective endotracheal intubation with and without neuromuscular blockade: a randomized controlled trial

The routine use of neuromuscular blocking drugs (NMBD) for endotracheal intubation in children is the subject of much controversy. The analysis of heart rate variability (HRV) can reveal information about the functional state of the autonomic nervous system (ANS). The purpose of this study was to determine if HRV elucidates differences in the sympathovagal balance of children undergoing elective endo-tracheal intubation with and without neuromuscular blockade (NMB). In this prospective study, 38 children (2-6 years) scheduled for adenotonsillectomy were randomized into two groups to receive fentanyl 2 μg·kg(-1) and propofol 4 mg·kg(-1) , with either mivacurium 0.25 mg·kg(-1) (NMB group) or saline solution (NoNMB group) for anesthesia induction. The same experienced, blinded anesthesiologist performed endotracheal intubation. Heart rate variability, RR intervals, ECG as well as an electroencephalogram were recorded with HRV and BIS XP monitors, respectively. Heart rate variability was analyzed in the frequency domain. There was no significant difference in HRV changes immediately after mivacurium administration compared with an administration of saline. The groups were comparable for the bispectral index value (NMB 35 [33-41] vs NoNMB 34 [32-42]) during endotracheal intubation. Changes in both the low-frequency power and the low-/high-frequency ratio immediately after endotracheal intubation compared with the unstimulated state before laryngoscopy were significantly higher without NMB (P = 0.015 and P = 0.006, respectively), whereas there was no significant difference with respect to the high-frequency power. The stress response during endotracheal intubation in pediatric patients represented by the frequency domain analysis of HRV was found to be higher without NMB. When mivacurium was added to a propofol-fentanyl induction regimen, the ANS alterations during endotracheal intubation decreased significantly.