HF Indices Research Articles

Reactivity of the autonomic nervous system in children of younger school age with mental retardation

Introduction. The functioning of the autonomic nervous system (ANS) to some extent affects various aspects of human health and general well-being. One of the main ANS functions is to ensure adaptation to the factors of the external and internal environment, carried out by the coordinated activity of the sympathetic and parasympathetic links. Determining the predominant type of ANS reactivity according to the characteristics of the heart rhythm makes it possible to predict the adaptive capabilities of the child’s body in the learning process in a personalized way. 
 The aim of the study was to study the trend in heart rate variability in children with special health conditions associated with disorders of the intellectual development, which characterizes the implementation of mechanisms for adapting the body to the conditions of schooling.
 Materials and methods. We examined one hundred sixty eight 7–11 years children of primary school age, including 54 children with special health abilities (SHA) (F70, F71), and 114 mentally healthy children. The study of heart rate variability was carried out using the hardware-software complex “ORTO Valeo”. There was analyzed TP, HF, LF, VLF, LF / HF; RMSSD, SDNN, Mo, AMo, ΔX, IN, AMo / Mo, Amo / ΔX; type of vegetative regulation.
 Results. In SHA children of primary school age, the LF, VLF, LF / HF indices are increased and HF is decreased relative to the control group, which indicates the predominance of the sympathetic link of the autonomic nervous system over the parasympathetic. When analyzing the spectral components in SHA children of primary school age, VLF (40.6%) and low HF (19.6%) dominate. According to the types of autonomic regulation in SHA children, the following ratio was found 50: 4: 33: 13, the central type of cardiac regulation dominates (type I).
 Limitations. The limitation of the study is due to the specifics of the individuals in the observation group – children of primary school age (7–11 years) with special health opportunities associated with mental retardation.
 Conclusion. SHA children of primary school age have high activity of sympathetic modulation, reduced resistance to stress, high tension of adaptive responses with the dominance of the central type of regulation of the cardiac activity. The revealed imbalance of the parameters of autonomic regulation in SHA children without corrective measures (including correction of physical status, psychoemotional and educational loads) threatens the development of a breakdown of adaptive responses to the effects of various internal and external factors, contributing to asthenization of regulatory systems.

Effect of Combined Exercise Training on Heart Rate Variability and Aerobic Capacity of Boys with Type 1 Diabetes

Background and Objective: Dysfunction in the autonomic nervous system can cause cardiovascular complications in patients with type 1 diabetes (T1D). The present study aimed to investigate the effect of combined exercise training on heart rate variability (HRV-5min), aerobic capacity (VO2max), and glycemic index in boys with T1D. Materials and Methods: In this semi-experimental research, 24 adolescent boys with insulin-dependent T1D and 12 healthy boys of the same age with an age range of 12 to 18 years were selected and divided into three groups: healthy, control diabetic, and exercise diabetic. The exercise diabetic group performed combined exercises for 12 weeks, three sessions a week. Blood variables and cardiac variables were measured 48 h before and 72 h after the intervention. Dependent t-tests and one-way analysis of variance were used for statistical analysis. Results: After the intervention, a significant increase in VO2max variables, high frequency HRV (HF) and a significant decrease in Resting Heart Rate Variables (HRrest), the ratio of low frequency to high frequency HRV (LF.HF) and glycemic index were observed in the exercise diabetic group (P<0.05). In addition, in the inter-group analysis of the difference between the pre-test and post-test results, a significant difference was observed in VO2max, HRrest, HF, LF.HF, and blood glucose indices in the exercise diabetic group compared to the healthy and diabetic control groups (P<0.05). Conclusion: Our results showed that combined exercise training along with insulin-dependent treatment could help to strengthen the cardiovascular system (HRV) in boys with T1D by improving the function of the parasympathetic branch of the autonomic nervous system.

Post-exercise heart rate recovery and its speed are associated with cardiac autonomic responsiveness following orthostatic stress test in men

Objective: The present study sought to expand upon prior investigations of the relationship between the post-exercise heart rate recovery (HRR) and the cardiac autonomic responsiveness after orthostatic stress test. Method: HRR at the 1st, 3rd, and 5th min after maximal exercise test were correlated with relative change (Δ%) of time-domain (CV, pNN50, and rMSSD) and frequency-domain (TP, LF, HF, and LF/HF ratio) indices of heart rate variability (HRV) after active orthostatic test in 46 healthy men. Statistical analysis employed non-parametric tests with a p-value set at 5%. Results: HRR at 1st min correlated with Δ%pNN50 (rs:0.36 – p = .02). In the 3rd and 5th min, these measures correlated with Δ%pNN50, Δ%rMSSD, Δ%CV, Δ%TP, and Δ%HF indices (rs:0.33, 0.59 – p ≤ .05). Coefficient of HRR at the 1st min correlated with Δ%pNN50, Δ%rMSSD, and Δ%HF (rs:0.28, 0.45 – p ≤ .05). The 3rd and 5th min showed correlation with Δ%pNN50, Δ%rMSSD, Δ%HF, Δ%CV, and Δ%TP (rs:0.37, 0.64 – p ≤ .05). No correlation was found with indices combined sympathetic-parasympathetic modulation and HRR. After the sample was divided into high and low parasympathetic responsiveness subgroups after the orthostatic test, faster HRR was associated with the degree of parasympathetic responsiveness (reduction) following postural change (p ≤ .05). Conclusion: HRR throughout the 1st to 5th min is positively correlated with parasympathetic responsiveness and overall cardiac autonomic modulation of HRV after the orthostatic stress test, and faster HRR is positively correlated with the relative degree of parasympathetic responsiveness after the active postural change at rest in healthy men.

Majmaah Bölgesi'nde (Suudi Arabistan Krallığı) Kardiyovasküler Hastalığı Olan Hastalarda Kardiyak Otonom Fonksiyon ile Metabolik Sendrom Arasındaki İlişki: Vaka Kontrol Gözlem Çalışması

Objective: Lacunae in literature persist regarding the mechanisms connected with the progression from metabolic syndrome (MetS) to Type 2 diabetes and cardiovascular disease (CVD). To validate heart rate variability (HRV), as a tool for progression of CVD in patients visiting cardiovascular outpatient clinic. Material and Methods: This crosssectional study involved screening of 126 patients for the presence of one or more cardiometabolic risk factors and followed with HRV measurement after categorizing them as MetS+ or control MetS-. Results: Time domain analysis showed a significant reduction between male and female of MetS- and MetS+ While frequency domain analysis in MetS+ male showed no difference, MetS+ female showed significant difference in TP and HF indices. With increasing number of metabolic components, the MetS+ males exhibited significant decrease in the time domain and increase in frequency domain indices of HRV. Body mass index (BMI), waist circumference (WC), high-density lipoprotein (HDL), and triglyceride (TG) were associated with time and frequency domain of HRV among MetS+ and MetS- males and females. Low density lipoprotein (LDL) was a significant predictor of SDNN, RRSSD, and NN50 in patients with MetS+ while HDL was a significant predictor of Standard deviation of normal-to-normal intervals (SDNN) and pNN50. BMI was significant predictor of SDNN and pNN50 in MetS- patients and NN50 in MetS+ patients. In MetS+, the significant predictor of HF was WC, TG, HDL and LDL and that of LF were TG and LDL while in MetS-, WC was significant predictor of LF and HDL of LF/HF. Conclusion: MetS+ females showed lower vagal activity and decreased sympathetic predominance as compared to MetS males suggesting greater cardiovascular risk.

Parasympathetic modulation during sleep time is reduced after maximal exercise, correlated with aerobic fitness in young women

abstract It is known that cardiovascular risk is increased during exercise and recovery. Thus, it is necessary to assess all the risk associated with exercise to minimize the possibility of cardiovascular events. The aim of this study was to verify whether a maximal exercise alters ambulatory cardiac autonomic modulation in untrained women and whether aerobic fitness is correlated to cardiac autonomic modulation. Twelve women (25.35 ± 5.44 years) were outfitted with the Holter monitor on an experimental (after maximum exercise) and a control day to heart rate variability (HRV) evaluation. Maximal exercise increased 24 h heart rate (82 ± 14 vs 77 ± 11 bpm; p = 0.04) and during sleep time (72 ± 14 vs. 65 ± 9 bpm; p = 0.01), reduced parasympathetic modulation (HF – n.u. 49.96 ± 11.56 vs 42.10 ± 14.98; p = 0.04), and increased low-frequency/high-frequency ratio (2.88 ± 3.24 vs 1.31 ± 0.60; p = 0.03) during sleep time compared to the control day. Aerobic fitness was correlated positively with LF, HF, and HF (n.u.) indices (r = 0.61 to 0.73, p < 0.05) and correlated negatively with LF (n.u.) and LF/HF ratio (Rho = - 0.57 to - 0.69; p < 0.05). Maximal exercise alters parasympathetic modulation during sleep time in untrained women. Ambulatory cardiac autonomic modulation after exercise is related to aerobic fitness.

Sedentary Behavior: A Key Component in the Interaction between an Integrated Lifestyle Approach and Cardiac Autonomic Function in Active Young Men.

This study aimed to verify the association between autonomic cardiac function (CAF) and the integration of caloric expenditure by physical activity (PA) intensity, sedentary behavior (SB), and sleep quality (PSQI) in active young men. Thirty-five subjects were included, and caloric expenditure in moderate-to-vigorous and light-intensity PA, SB, and PSQI were assessed using questionnaires. Heart rate variability (HRV) was recorded for short periods of time in the supine and orthostatic positions. Multiple linear regression was realized unadjusted and adjusted for covariables, such as age, body mass index, and fat mass. No adjusted analysis indicated that, in the supine position, there were negative associations between the SB and the TP, HF, and NorHF indices, and positive associations between SB and NorLF and LF/HF. In the orthostatic position, an interaction between SB and NorLF was found. Significance of proportion with the TP, HF, and LF/HF indices was confirmed. When adjusted, for the supine position, negative interactions were documented between SB and the TP as well as the HF indices, and between PSQI and the LF/HF index, with interference under the HF and LF/HF indices. Finally, our findings indicate that the proposed approach interacts with CAF, and SB is significantly related to CAF in young active men.

Waist-Stature Ratio And Its Relationship With Autonomic Recovery From Aerobic Exercise In Healthy Men

Autonomic modulation and cardiorespiratory variables are influenced by numerous factors, including anthropometric variables. We investigated autonomic recovery following aerobic exercise in healthy men with different waist-stature ratio (WSR) values. The study was conducted with 52 healthy men aged 18 to 30 years, divided into groups according to the WSR: G1 – between 0.40 and 0.449 (N = 19), G2 – between 0.45 and 0.50 (N = 28) and G3 – between 0.5 and 0.56 (N = 5). The subjects endured 15 minutes seated and at rest followed by an aerobic exercise and then remained seated for 60 minutes and at rest during recovery from exercise. Heart rate (HR) variability (HRV) (rMSSD, SD1, HF [ms2]) and cardiorespiratory variables were analyzed before and after exercise. Recovery of respiratory rate, diastolic blood pressure, SD1 and HF indices were delayed in G2. G3 presented delayed recovery after the maximal effort test while no difference with G2 was noted in the moderate intensity. Correlation and linear regression analysis indicated association of WSR, body mass index and waist circumference with HRV indices in the recovery from aerobic exercise (45 to 60 minutes after exercise) in G2. In conclusion, healthy men with higher WSR accomplished delayed autonomic recovery following maximal effort exercise.

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.

Comparison between heart rate variability and pulse rate variability during different sleep stages for sleep apnea patients

The usefulness of heart rate variability (HRV) in the clinical research has been verified in numerous studies. However, it is controversy that using pulse rate variability (PRV) as a surrogate of HRV in different clinical applications. We aimed to investigate whether PRV extracted from finger pulse photoplethysmography (Pleth) signal could substitute HRV from ECG signal during different sleep stages by analyzing the common time-domain, frequency-domain and non-linear indices. Seventy-five sleep apnea patients were enrolled. For each patient, ECG and Pleth signals were simultaneously recorded for the whole night using Alice Sleepware Polysomnographic System and the sleep stage signals were automatically calculated by this System. Time-domain, frequency-domain and non-linear indices of both HRV and PRV were calculated for each sleep stage. Mann-Whitney U-test showed that for both time-domain and frequency-domain indices, there were no statistical differences between HRV and PRV results during all four sleep stages. For non-linear indices, sample entropy reported statistical differences between HRV and PRV results for N1, N2 and REM sleeps (all P< 0.01) whereas fuzzy measure entropy only reported statistical differences for REM sleep (P< 0.05). SDNN, LF and LF/HF indices decreased for both HRV and PRV with the sleep deepening while HF and non-linear indices increased. In addition, there were strong and significant correlation between HRV and PRV indices during all four sleep stages (all P< 0.01). PRV measurement could present the similar results as HRV analysis for sleep apnea patients during different sleep stages.

Involvement of rest diastolic arterial pressure in autonomic heart rate recovery from exercise in normotensive men

OBJECTIVE: Rest arterial pressure has been shown to be associated with cardiovascular mortality. Autonomic heart rate control during recovery from exercise is estimated to detect changes in cardiovascular system, which may lead to cardiovascular diseases. We assessed the involvement of rest diastolic arterial pressure (DAP) on heart rate dynamics after exercise in normotensive physically active men. METHOD: We evaluated healthy physically active men aged 18 to 22 years old divided into two unequal groups: G1- rest DAP between 80 and 90 mmHg (N=11) and G2- rest DAP < 80mmHg (N=24). Volunteers performed physical exercise on a treadmill with intensity equivalent to 60% of Vmax. Heart rate recovery in the first (HRR1) and third (HRR3) minute after exercise were measured and heart rate variability (HRV) was examined in the time and frequency domain. Additionally, we performed the quantitative analysis of the Poincare plot. HRV was recorded in the following phases: the 10-minute period before exercise, during exercise and the 60 minute period after exercise. RESULTS: We found no significant difference between G1 and G2 concerning HRV changes during exercise. The G2 group exhibited a delayed recovery of SDNN, RMSSD, RRTri, LF, HF, LF/HF, SD1 and SD2 indices during recovery from exercise. HRR1 and HRR3 was greater in the G2 group. CONCLUSION: Normotensive physically active men with DAP between 80 and 90 mmHg presented faster heart rate recovery and an accelerated recovery of heart rate autonomic control after aerobic exercise.

Impact of malnutrition on cardiac autonomic modulation in children

ObjectiveTo compare the autonomic behavior between malnourished children and a control group using analysis of heart rate variability (HRV). MethodData were analyzed from 70 children who were divided into two groups: malnourished and eutrophic, according to the Z‐score nutritional status for height and age. For analysis of HRV indices, heart rate was recorded beat to beat with the child in the supine position for 20min. The analysis of these indices was performed using linear methods, analyzed in the time and frequency domains. Student's t‐test for unpaired data and the Mann–Whitney test were used to compare variables between groups, with a significance level of 5%. ResultsA reduction in systolic and diastolic blood pressure and an increase in heart rate were found in malnourished children compared to eutrophic children. The HRV indices suggested that malnourished children present reductions in both sympathetic and parasympathetic autonomic nervous system activity. The SDNN, rMSSD, NN50, pNN50, SD1, SD2, TINN, LF (ms2), and HF (ms2) indices were lower in malnourished children. ConclusionMalnourished children present changes in cardiac autonomic modulation, characterized by reductions in both sympathetic and parasympathetic activity, as well as increased heart rate and decreased blood pressure.

Post-exercise heart-rate recovery correlates to resting heart-rate variability in healthy men.

The relationship between post-exercise heart-rate recovery (HRR) and resting cardiac autonomic modulation is an incompletely explored issue. To correlate HRR with resting supine and orthostatic autonomic status. HRR at the 1st, 3th, and 5th min following maximal treadmill exercise were correlated with 5-min time-domain (CV, pNN50 and rMSSD) and frequency-domain (TP, LF, HF, LFn, HFn, and LF/HF ratio) indices of heart-rate variability (HRV) in both supine and standing positions in 31 healthy physically active non-athletes men. Statistical analysis employed non-parametric tests with two-tailed pvalue set at 5%. Absolute HRR and Δ%HRR at each post-exercise time did not correlated with HRV in supine position, as well as at 1st min in standing position. At the 3rd min and 5th min, these measures negatively correlated with pNN50, rMSSD, TP, and HF indices, and only in the 5th min, they showed negative correlation with HFn and positive correlation with LF, LFn, and LF/HF ratio in the standing position. Coefficient of HRR (CHRR) at the 1st min negatively correlated with pNN50 and rMSSD and at 3rd and 5th min showed positive correlation with LFn and LF/HF ratio in supine position. With HRV indices in standing position CHRR from the 1st to 5th min showed the same respective negative and positive correlations as the other measures. HRR from the 1st to 5th min post-exercise negatively correlated with parasympathetic modulation in resting orthostatic, but showed no correlation in supine position. At the 3rd and 5th min, a positive correlation with combined sympathetic-parasympathetic modulation in both positions was observed.

Impact of malnutrition on cardiac autonomic modulation in children

ObjectiveTo compare the autonomic behavior between malnourished children and a control group using analysis of heart rate variability (HRV). MethodData were analyzed from 70 children who were divided into two groups: malnourished and eutrophic, according to the Z-score nutritional status for height and age. For analysis of HRV indices, heart rate was recorded beat to beat with the child in the supine position for 20min. The analysis of these indices was performed using linear methods, analyzed in the time and frequency domains. Student's t-test for unpaired data and the Mann–Whitney test were used to compare variables between groups, with a significance level of 5%. ResultsA reduction in systolic and diastolic blood pressure and an increase in heart rate were found in malnourished children compared to eutrophic children. The HRV indices suggested that malnourished children present reductions in both sympathetic and parasympathetic autonomic nervous system activity. The SDNN, rMSSD, NN50, pNN50, SD1, SD2, TINN, LF (ms2), and HF (ms2) indices were lower in malnourished children. ConclusionMalnourished children present changes in cardiac autonomic modulation, characterized by reductions in both sympathetic and parasympathetic activity, as well as increased heart rate and decreased blood pressure.

Effects of environmental stress following myocardial infarction on behavioral measures and heart failure progression: The influence of isolated and group housing conditions

BackgroundHeart failure (HF) prognosis is negatively influenced by adverse environmental conditions associated with psychological distress and depression. The underlying mechanisms are not well understood because of insufficient experimental control in prior clinical and epidemiological studies. Using a validated animal model we examined whether distress-producing environmental manipulations (social isolation and crowding) increase HF progression following myocardial infarction (MI). MethodsMI was induced using coronary artery ligation in 8-week old male Wistar rats (N=52) and results were compared to sham surgery (N=24). Housing conditions were randomly assigned at 5days post MI or sham surgery (1/cage=isolation, 2/cage=standard reference condition, or 4/cage=crowding) and continued for 17weeks until the end of observation. The open field test was used to test behavioral responses. Echocardiograms were obtained at weeks 8 and 16, and left ventricular (LV) weight at week 17. ResultsHousing conditions increased behavioral markers of distress (p=0.046) with the strongest effects for the isolated (1/cage) (p=0.022). MI did not increase distress-related behaviors compared to sham. MI-surgery resulted in characteristic HF indices (left ventricular ejection fraction (LVEF) at week 16=46±12% vs. 80±7% in sham, p<0.001). Housing condition was not related to LVEF or LV weight (p>0.10). ConclusionsAdverse environmental conditions, particularly isolated housing, produce increases in some of the behavioral indicators of distress. No effects of housing were found on post-MI progression of HF. The distress–HF associations observed in humans may therefore reflect common underlying factors rather than an independent causal pathway. Stronger environmental challenges may be needed in future animal research examining distress as related HF progression.

235: Heart rate variability in the first five minutes of the tilt test to predict syncope?

Vasovagal syncope mechanisms, diagnostic tools and treatments are currently strongly explored and debated. The aim of this study is to specify the early cardiac autonomic adaptations to tilt test in negative and positive (cardio-inhibitory and vasodepressor) subjects. Healthy men (n=81) from 18 to 35 years old underwent a 45 min 80° tilt test after a 15 min rest. Three clinicians independently classified each test results according to the VASIS classification: negative (NEG), mixed, cardio-inhibitor (CI) or vasodepressive (VD) syncope. Only three groups were studied: the NEG (n=13), CI (n=11) and VD (n=8). ECG recorded during 5 min of resting (Rest5) and the first 5 min of the tilt test (Early5) were compared within and between groups. ECG signals were analysed with the validated algorithm Segmenta (LTSI, Rennes) to calculate usual HRV parameters: Ptot, LF, HF, LFnu, HFnu. First , within group comparisons showed that in NEG subjects from Rest5 to Early5, HF and HFnu decreased (p<0,01) and LF (p<0,05) and LFnu (p<0,01) increased. VD subjects showed similar responses (p<0,05), except for HF indices (NS). In CI subjects LF and HF indices weren’t significantly different between Rest5 and Early5. Second , between groups comparisons of the relative adaptations (%) from Rest5 to Early5 showed that the increase in LFnu was higher in NEG (+180±80%) than in CI (+66±50%) (p<0,01). HFnu decrease was also higher in NEG (-66±5%) than in CI (-38±9%) (p<0,05). Our results suggest a lack of sympatho-vagal balance activation in the first 5 min of tilt test in subjects with vasovagal syncope. CI and VD syncope groups show a lower decrease of HF indices in the Early5. Moreover, CI group shows a lower increase of LF indices. A perspective of this work is the set of cut-off values from data recorded over the first 5 min of tilt test to estimate the risk and the type of vasovagal reaction, based on a bigger population. Figure (abstract 235) – LFnu and HFnu variations (%) in NEG and CI

Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) and electrosensibility (ES) – Are they connected?

The tendency of experiencing unpleasant symptoms in the proximity of working electric devices is called idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF). Evidence about psychophysiological backgrounds of the phenomenon (i.e., detection ability and mechanisms of symptom generation) is not yet conclusive. Participants of the provocation experiment were 29 individuals with self-reported IEI-EMF and 42 control persons. Participants completed questionnaires (symptom expectations, somatosensory amplification - SSAS, modern health worries radiation subscale - MHW-R), and attempted to detect the presence of 50 Hz 0.5 mT magnetic field (MF) directed to their right arm in 20 subsequent 1-min sessions. Heart rate was also recorded and various indices of heart rate variability (HF, LF/HF, SDNN) were calculated. Using the methodology of the signal detection theory, individuals with IEI-EMF as opposed to the control group showed a higher than random detection performance (d' differed slightly but statistically significantly from zero), and they used a significantly lower criterion (β value) when deciding about the presence of the MF. Detection sessions followed by correct decisions (hits or correct rejections) were characterized by higher HRV (SDNN and HF indices) than periods followed by errors (misses or false alarms). Previous expectations and affiliation to the IEI-EMF group were significant predictors of symptoms reported following exposure. IEI-EMF was closely related to MHW-R and SSAS scores. Detection of MF might be possible for people with IEI-EMF to some extent. Although heightened sensibility to MFs may play a role in the development and/or in the perpetuance of the IEI-EMF phenomenon, symptoms attributed to the MF seem to be mainly of psychogenic origin.

Autonomic dysfunction in 2009 pandemic influenza A (H1N1) virus-related infection: A pediatric comparative study

BackgroundRelationship between respiratory morbidity and influenza virus has been well-documented in infants, whatever their age. However, in spite of severe cardiac and respiratory events of central origin, autonomic dysfunction potentially induced by this virus is poorly understood. We thus explored the autonomic nervous system (ANS) profile of infected infants during the 2009 pandemic influenza disease. MethodA group of 10 consecutive infants (5<1year and 5>1year) presenting with nvH1N1 infection was evaluated with heart rate variability (HRV) and spontaneous baroreflex (SBR) through a recording during a 15-minute period of quiet sleep as well as 24h holter monitoring. The same recordings were performed in 10 control subjects, paired for gestational and postnatal age. HRV sympathetic and parasympathetic (VLF, LF and HF) indices were obtained using spectral-domain analysis, and spontaneous baroreflex sensitivity (SBR) using simultaneous non-invasive continuous measure of arterial pressure and heart rate. ResultsThe group of infants less than 1year had similar value as control group. Conversely, the group of infants more than 1year showed significant lower spectral total power values (Ptot: 3347 vs. 5926ms2/Hz, p<0.1) and significant lower VLF, LF and HF indices (all p<0.05) than the control group. ConclusionnvH1N1 infection in child could be associated with severe central autonomic dysfunction. Due to potential severe consequences, a systematic evaluation of autonomic regulation should be performed in order to avoid dramatic events.

Application of Cardiac Autonomous Indices in the Study of Neurogenic Erectile Dysfunction

A research area of increasing interest consists of studying the benefits of using spectral analysis to screen neurogenic erectile dysfunctions. Our hypothesis is that spectral analysis consists of a non-invasive and simple procedure to investigate such patients. Subjects were allocated into two groups: control, no erectile dysfunction (n = 17), and patients with erectile dysfunction (n = 15). RR intervals (RRI), systolic blood pressure, diastolic blood pressure and baroreflex sensitivity recordings were performed continuously in the supine position, followed by the seated position, and finally standing position. In the supine position, the control group had a higher RRI and a lower diastolic blood pressure. For frequency domain analyses of RRI in the supine position, the erectile dysfunction group had a higher normalized low-frequency (LF) index and low-frequency/high-frequency (LF/HF) ratio while showing a lower normalized HF index. In the seated position, the erectile dysfunction group presented a higher LF/HF ratio. Regarding systolic blood pressure, the erectile dysfunction group showed lower normalized LF and higher normalized HF indices only in the supine position. The α index in HF was lower in the erectile dysfunction group in the three positions. Spectral analyses of cardiac sympathovagal drive constitute a fruitful non-invasive approach to evaluate alterations in cardiovascular autonomic modulation in neurogenic erectile dysfunction patients.

Analysis of cardiac autonomic modulation in obese and eutrophic children

INTRODUCTION:Obesity causes alterations in cardiac autonomic function. However, there are scarce and conflicting data on this function with regard to heart rate variability in obese children.OBJECTIVE:To compare the autonomic function of obese and eutrophic children by analyzing heart rate variability.METHODS:One hundred twenty-one children (57 male and 64 female) aged 8 to 12 years were distributed into two groups based on nutritional status [obese (n = 56) and eutrophic (ideal weight range; n = 65) according to the body mass index reference for gender and age]. For the analysis of heart rate variability, heart rates were recorded beat by beat as the children rested in the dorsal (prone) position for 20 minutes. Heart rate variability analysis was carried out using linear approaches in the domains of frequency and time. Either Student's t-test or the Mann-Whitney U-test was applied to compare variables between groups. Statistical significance was set at 5%.RESULTS:The SDNN, RMSSD, pNN50, SD1, SD2, LF and HF indices in milliseconds squared were lower among the obese children when compared to the eutrophic group. There were no alterations in the SD1/SD2 ratio, LF/HF ratio, LF index or HF index in normalized units. There was a significant difference between groups in the RR interval (R-to-R EKG interval).CONCLUSION:The obese children exhibited modifications in heart rate variability, characterized by a reduction in both sympathetic and parasympathetic activity. These findings stress the need for the early holistic care of obese children to avoid future complications.

Analysis of cardiac autonomic modulation in obese and eutrophic children

Obesity causes alterations in cardiac autonomic function. However, there are scarce and conflicting data on this function with regard to heart rate variability in obese children. To compare the autonomic function of obese and eutrophic children by analyzing heart rate variability. One hundred twenty-one children (57 male and 64 female) aged 8 to 12 years were distributed into two groups based on nutritional status [obese (n = 56) and eutrophic (ideal weight range; n = 65) according to the body mass index reference for gender and age]. For the analysis of heart rate variability, heart rates were recorded beat by beat as the children rested in the dorsal (prone) position for 20 minutes. Heart rate variability analysis was carried out using linear approaches in the domains of frequency and time. Either Student's t-test or the Mann-Whitney U-test was applied to compare variables between groups. Statistical significance was set at 5%. The SDNN, RMSSD, pNN50, SD1, SD2, LF and HF indices in milliseconds squared were lower among the obese children when compared to the eutrophic group. There were no alterations in the SD1/SD2 ratio, LF/HF ratio, LF index or HF index in normalized units. There was a significant difference between groups in the RR interval (R-to-R EKG interval). The obese children exhibited modifications in heart rate variability, characterized by a reduction in both sympathetic and parasympathetic activity. These findings stress the need for the early holistic care of obese children to avoid future complications.