Time Domain Measures Of Heart Rate Variability Research Articles

Reduced heart rate variability is related to fluctuations in psychological stress levels in daily life.

Laboratory-based studies have shown that psychological stress caused by response to various stressors triggers acute changes in the cardiovascular system. A better understanding is needed of the emerging evidence on temporal associations between psychological stress and cardiovascular responses in natural settings. This study examined the association of psychological stress and heart rate variability (HRV) in daily life, at high resolution over 2weeks, taking the effect of physical activity into account. Participants (n=34) completed ecological momentary assessments (EMA) 6 times per day, reporting levels of perceived stress, low-arousal negative affect (LNA), and high-arousal negative affect. Chest-mounted heart-rate monitors were worn to assess HRV. Multilevel models were used to examine the association between psychological stress levels and preceding/subsequent HRV. Reduced time domain HRV measures (mean and standard deviation of R-wave to R-wave intervals) during the prior hour predicted higher levels of perceived stress. Frequency domain HRV measures higher low to high frequency (LF/HF) and lower HF to total power (HF nu) ratios during the preceding 10min predicted higher perceived stress levels, suggesting the dominance of sympathetic nervous system activity. EMA reports of higher perceived stress levels were associated with reduced time domain HRV measures during the following 10min. On the other hand, higher LNA were related to increased HRV measures, such as lower LF/HF and higher HF nu during the following hour. The dynamic associations observed may have therapeutic implications for 'just-in-time' interventions in the management of daily stress and cardiovascular health.

Using Physiological Markers to Assess Comfort during Neuromuscular Electrical Stimulation Induced Muscle Contraction in a Virtually Guided Environment: Pilot Study for a Path toward Combating ICU-Acquired Weakness.

We assessed the feasibility of implementing a virtually guided Neuromuscular Electrical Stimulation (NMES) protocol over the tibialis anterior (TA) muscle while collecting heart rate (HR), Numeric Pain Rating Scale (NPRS), and quality of contraction (QoC) data. We investigated if HR, NPRS, and QoC differ ON and OFF the TA motor point and explored potential relationships between heart rate variability (HRV) and the NPRS. Twelve healthy adults participated in this cross-sectional study. Three NMES trials were delivered ON and OFF the TA motor point. HR, QoC, and NPRS data were collected. There was no significant difference in HRV ON and OFF the motor point (p > 0.05). The NPRS was significantly greater OFF the motor point (p < 0.05). The QoC was significantly different between motor point configurations (p < 0.05). There was no correlation between the NPRS and HRV (p > 0.05, r = -0.129). We recommend non-electrical methods of measuring muscle activity for future studies. The NPRS and QoC can be administered virtually. Time-domain HRV measures could increase the validity of the protocol. The variables should be explored further virtually to enhance the protocol before eventual ICU studies.

Sex differences in heart rate variability measures that predict alcohol drinking in rats.

Problem alcohol drinking continues to be a substantial cost and burden. In addition, alcohol consumption in women has increased in recent decades, and women can have greater alcohol problems and comorbidities. Thus, there is a significant need for novel therapeutics to enhance sex-specific, individualized treatment. Heart rate (HR) and HR variability (HRV) are of broad interest because they may be both biomarkers for and drivers of pathological states. HRV reflects the dynamic balance between sympathetic (SNS, 'fight or flight') and parasympathetic (PNS, 'rest and digest') systems. Evidence from human studies suggest PNS predominance in women and SNS in men during autonomic regulation, indicating the possibility of sex differences in risk factors and physiological drivers of problem drinking. To better understand the association between HRV sex differences and alcohol drinking, we examined whether alcohol consumption levels correlated with time domain HRV measures (SDNN and rMSSD) at baseline, at alcohol drinking onset, and across 10min of drinking, in adult female and male Wistar rats. In particular, we compared both HRV and HR measures under alcohol-only and compulsion-like conditions (alcohol + 10mg/L quinine), because compulsion can often be a significant barrier to treatment of alcohol misuse. Importantly, previous work supports the possibility that different HRV measures could be interpreted to reflect PNS versus SNS influences. Here, we show that females with higher putative PNS indicators at baseline and at drinking onset had greater alcohol consumption. In contrast, male intake levels related to increased potential SNS measures at drinking onset. Once alcohol was consumed, HR predicted intake level in females, perhaps a pharmacological effect of alcohol. However, HRV changes were greater during compulsion-like intake versus alcohol-only, suggesting HRV changes (reduced SNS in females, reduced PNS and increased HR in males) specifically related to aversion-resistant intake. We find novel and likely clinically relevant autonomic differences associated with biological sex and alcohol drinking, suggesting that different autonomic mechanisms may promote differing aspects of female and male alcohol consumption.

Effect of Slow Breathing Exercise on Time Domain Heart Rate Variability in Transfusion Dependent Thalassemic Patients

Time domain measure of heart rate variability (HRV) is a newersystem to seek out any alteration in cardiacautonomic nerve function (CANF) in transfusion dependent thalassemic (TDT) patients. Slow breathing exercise(SBE) plays important role in improvement of HRV in health and various diseases.This research aims to observe theeffect of slow breathing exercise (SBE) on time domain measures of HRV in TDT patients. This prospectiveinterventional study was done in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University(BSMMU), Dhaka in 2018 on 60 male TDT patients aged 15-30 years. Thirty patients received conventionaltreatment and 30 patients performed slow breathing exercise along with the conventional treatment for 3 months. Ageand sex matched healthy control were taken to compare. All subjects were followed up at baseline and after 3 months.Time domain HRV parameters were recorded by Power Lab 8/35. For statistical analysis paired sample 't' test andindependent sample 't' test were done. Mean RR interval, Mean SD, RMSSD and pRR50% were found significantlylower in TDT patients compared to healthy control at baseline and on the other hand mean heart rate was significantlyhigher in this group of patients. After 3 months of slow breathing exercise, significant decrement of mean heart rateand significant increment of others parameters occurred with trend of improvement in cardiac autonomic nervefunction in TDT patients. In conclusion slow breathing exercise may improve cardiac autonomic nerve function andsympathovagal balance in transfusion dependent thalassemic patients. Bangabandhu Sheikh Mujib Med. Coll. J. 2022;1(2):65-69

Core temperature decline prior to sleep onset is associated with nocturnal heart rate variability

Impaired thermoregulation is associated with poor sleep and autonomic dysfunction. Previous studies demonstrate an association between core body temperature (CBT) dipping and an increase in heart rate variability (HRV) prior to sleep onset. However, the relationship between the rate of CBT decline prior to sleep onset and nocturnal HRV has not been established. The purpose of this study was to investigate the relationship between the rate of CBT decline prior to sleep onset and nocturnal HRV in objectively poor sleepers. We hypothesized a blunted pre-sleep CBT decline would correspond to reduced nocturnal HRV. Fifteen participants (9 males, 6 females; age, 33±4 years; BMI 27±1 kg/m 2 ) underwent an 8-hour overnight sleep opportunity with continuous polysomnography (PSG) and 2-lead electrocardiogram monitoring. A temperature monitoring pill (CoreTempTM, HQ Inc., Palmetto, FL) was ingested with a standardized dinner to record CBT every 10 seconds throughout the sleep period. Core temperature was sampled every 5 minutes from the core temperature tracing one hour prior to sleep onset until final awakening. The rate of CBT decline prior to sleep onset was measured as the slope of CBT values from 1 hour prior to lights out until PSG sleep onset. Nocturnal HRV measures including the root mean squared of successive differences (RMSSD), percentage of R-R intervals (RRI) varying by greater than 50 ms (pNN50), and the high frequency (HF) power of the RRI were determined across the night in stage 2 (N2), stage 3 (SWS), and rapid eye movement (REM) sleep stages. Bivariate correlations were performed to assess the association between CBT rate of decline and nocturnal HRV measures. An inverse correlation was observed between the rate of CBT prior to sleep onset and the RRI in N2 (R= -0.743, p=0.002), SWS (R = -0.730, P = 0.002), and REM (R = -0.708, P = 0.003). Additionally, the rate of pre-sleep CBT decline was inversely correlated with time domain HRV measures in N2 (pNN50: R= -0.598, p= 0.019; RMSSD: R = -0.557, P = 0.031) and SWS (pNN50: R = -0.542, P = 0.037; RMSSD: R = -0.591, P = 0.020). A blunted rate of CBT was further correlated to decreased HF log10 in N2 (R= -0.592, p= 0.020) and REM (R= -0.602, p= 0.018). Our results indicate an association between blunted core temperature decline prior to sleep onset and reduced nocturnal HRV. These findings suggest that adequate thermoregulation prior to sleep onset may have lasting associations with nocturnal cardiac autonomic function. Support is provided by the National Institutes of Health (AA-024892, U54GM115371; P20GM103474). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Pilot Study of Real-World Monitoring of the Heart Rate Variability in Amyotrophic Lateral Sclerosis.

AimsCardiovascular dysautonomia may impact the quality of life and survival in amyotrophic lateral sclerosis (ALS). Such dysfunction is not systematically assessed in these patients. Wearable devices could help. The feasibility of a wearable biosensor to detect heart rate variability (HRV), a physiological marker of sympathovagal balance, was studied for the first time in real-world settings in ALS.MethodsFive ALS patients (two early/three late; one bulbar-onset; mildly-to-moderately disabled) and five age/sex/BMI/comorbidities-matched controls underwent assessment of 3-day HRV via VitalConnect biosensor (worn on the left thorax). De-identified data captured by the biosensor were transferred to a secure cloud server via a relay Bluetooth device. Baseline ALS severity/anxiety and physical activity during testing were documented/quantified. Time-domain HRV measures (i.e., pNN50) were analyzed.ResultsAn overall 3-day abnormal HRV (pNN50 < 3%), was found in three out of five patients (mean ± SD for the group, 2.49 ± 1.51). Similar changes were reported in controls (12.32 ± 21.14%). There were no statistically significant relationships between pNN50 values and baseline anxiety or physical activity during the tested days (p > 0.05 for both groups). A negative correlation was found between pNN50 values and age in patients (p = 0.01) and controls (p = 0.09), which is similar with what is found in the general population. In line with prior studies, pNN50 values were independent of disease stage (p = 0.6) and disability (p = 0.4).ConclusionsThese preliminary results suggest that remote HRV measures using the VitalConnect is feasible and may constitute an improved strategy to provide insights into sympathovagal balance in ALS. Further work with larger sample sizes is warranted.

Cardiac Autonomic Dysfunction Is Associated With Risk of Diabetic Kidney Disease Progression in Type 2 Diabetes Mellitus.

BackgroundEvidence on the relationship between heart rate variability (HRV) and albumin-to-creatinine ratio (ACR) combined with estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes mellitus (T2DM) is rare. Thus, this study aimed to investigate the relationship between heart rate variability and the risk of diabetic kidney disease (DKD) progression in diabetes patients.MethodOverall, 747 T2DM patients who were admitted to the Second Affiliated Hospital of Nanchang University underwent 24-hour dynamic electrocardiograms for HRV analysis. Time-domain HRV measures included mean heart rate, standard deviation of the R-R interval (SDNN), SDNN index, root mean squared difference of successive RR intervals (RMSSD), and percent of adjacent RR intervals with a difference greater than 50 ms (PNN50). Frequency-domain measures included low frequency (LF), very low frequency (VLF), high frequency (HF) components and LF-to-HF ratio. The risk of DKD progression was determined by combining ACR and eGFR and stratified as low risk (Group A), moderately increased risk (Group B), high risk (Group C), and very high risk (Group D) based on the Kidney Disease: Improving Global Outcomes guidelines.ResultThere were significant differences in HRV parameters among the four risk groups (SDNN: 113 ms vs 109 ms vs 101 ms vs 81 ms, P<0.01; LF: 240.2 ms2 vs 241.1 ms2 vs 155.2 ms2 vs 141.9 ms2, P<0.01; LF-to-HF ratio: 1.70 vs 1.24 vs 1.12 vs 0.93, P<0.01; VLF: 723.7 ms2 vs 601.1 ms2 vs 446.4 ms2 vs 356.3 ms2, P<0.01). A very high risk of DKD progression was significantly associated with a lower SDNN (β=-19.5, 95% CI: -30.0 to -10.0, P<0.01), and moderately increased, high, and very high risks were associated with lower LF-to-HF ratio and VLF (P<0.05). Logistic regression analysis showed that group D had a higher risk of reduced SDNN, LF-to-HF ratio, and VLF compared with group A after adjusting for systolic blood pressure, glycated haemoglobin, haemoglobin, high-density lipoprotein cholesterol, and age (odds ratio (95% CI): 0.989 (0. 983–0.996), 0.674 (0.498–0.913), and 0.999 (0.999–1.000), respectively).ConclusionCardiac autonomic dysfunction is associated with a risk of DKD progression in adults with T2DM, and reduced heart rate variability increased such risk. Thus, HRV screening may be necessary in patients with T2DM, especially those with high proteinuria.

Investigation of the Effect of eSport on HRV Signal by Using Poincaré Plot Analysis

In this work, in order to determination of effect of a puzzle video game on HRV (Heart rate variability) signal, Poincare plot analysis is used. The linear and nonlinear dynamics of HRV were evaluated using HRV recordings obtained from each player at the time of play and rest. For this purpose, we have correlated the Poincaré plot descriptors with standard HRV measures derived from time- and frequency-domain methods. In addition, the correlations between the descriptors of the Poincaré plot along with the frequency and time domain measures of HRV have evaluated for the game stage. Statistically significant values were observed in eSport players in gaming and during resting. The obtained results show that play and rest can be separated by using the features obtained from the Poincare plot.

Sex differences in autonomic recovery following repeated sinusoidal resistance exercise.

A simple bodyweight squat is sufficient to cause substantial stress on the autonomic nervous system (ANS) via ~30–50 mmHg blood pressure (BP) oscillations. However, it is unknown to the extent of the ANS is impacted during and immediately following bodyweight and resistance squat‐stand maneuvers (SSM) while considering chromosomal sex. Thirteen females and twelve males performed four, 5‐minute bouts of squat‐stand maneuvers (SSM); two at 0.05 Hz (10‐second squat/10‐second stand) and two at 0.10 Hz (5‐s squat/5‐s stand). The SSM were performed using bodyweight resistance and additional external resistance (~20% of bodyweight). Five‐minutes of quiet‐sitting and quiet‐standing were completed immediately following both bodyweight and resistance squats. Heart rate variability (HRV) and baroreceptor sensitivity metrics were extracted from beat‐to‐beat electrocardiography and systemic BP recordings. Repeated measure Analysis of Variance with generalized eta‐squared effect sizes assessed differences between SSM task type and chromosomal sex on ANS metrics. Despite added resistance eliciting greater elevations in blood pressure, no differences in ANS function were noted during competition and recovery between SSM tasks (all p > 0.050; negligible/small effect sizes). During recovery, females had an elevated heart rate (p = 0.017; small effect size), greater time‐domain HRV measures (p < 0.047; small effect size), greater high‐frequency domain HRV measures (p = 0.002; moderate effect size), and reduced low‐frequency domain HRV measures (p = 0.002; moderate effect size). A healthy ANS can modulate repetitive cardiovascular stressors via squat‐stand maneuvers in a harmonious manner irrespective of added low‐level resistance. Females were more parasympathetically driven following low‐level resistance exercise/stress, which may be a cardioprotective trait.

Relationship Between Heart Rate Variability and Pulse Rate Variability Measures in Patients After Coronary Artery Bypass Graft Surgery.

Background: Heart rate variability (HRV) and pulse rate variability (PRV) measures are two kinds of physiological indices that can be used to evaluate the autonomic nervous function of healthy subjects and patients with various kinds of illness.Purpose: In this study, we compared the agreement and linear relationship between electrocardiographic signals (ECG)-derived HRV and photoplethysmographic signals (PPG)-derived right hand PRV (R-PRV) and left hand PRV (L-PRV) measures in 14 patients over 1 year after coronary artery bypass graft (CABG) surgery.Method: The ECG and PPG signals of the patient were recorded simultaneously for 10 min in a supine position. The last 512 stationary RR intervals (RRI) and peak-to peak intervals (PPI) of pulse wave were derived for data analysis. Bland-Altman plot was used to assess the agreement among HRV and both hand PRV measures, while linear regression analysis was used to examine the relationship among corresponding measures of HRV, R-PRV, and L-PRV.Result: The results revealed significant differences in total power (TP), very low-frequency power (VLF), low-frequency power (LF), high-frequency power (HF), and normalized VLF (VLFnorm) among HRV, R-PRV, and L-PRV. Bland-Altman plot analysis showed good agreements in almost all measures between R-PRV and L-PRV, except insufficient agreement was found in LF/HF. Insufficient agreements were found in root mean square successive difference (RMSSD), normalized HF (HFnorm), and LF/HF indices between HRV and L-PRV, and in VLFnorm, HFnorm, and LF/HF indices between HRV and R-PRV. Linear regression analysis showed that the HRV, R-PRV, and L-PRV measures were all highly correlated with one another (r = 0.94 ~ 1; p < 0.001).Conclusion: Though PRV measures of either hand are not surrogates of HRV measures, they might still be used to evaluate the autonomic nervous functions of CABG patients due to the moderate to good agreements in most time-domain and frequency-domain HRV measures and the strong and positive correlations among HRV and both hands PRV measures in CABG patients.

Concussion History and Heart Rate Variability During Bouts of Acute Stress.

After a sport-related concussion, many athletes experience persisting neurophysiological alterations. These alterations may be absent at rest but emerge during moments of physiological stress. Unnoticed and untreated neurophysiological dysfunction may negatively affect long-term neurologic health in adolescent athletes, as they are at a critical point in development. To assess cardio-autonomic functioning in athletes with and those without a history of concussion by quantifying measures of heart rate variability (HRV) during times of physical and mental exertion. Case-control study. Research laboratory. Thirty-four male Hockey Quebec Midget-AAA hockey players were separated into those with (n = 16; age = 16.06 ± 0.73 years, body mass index = 23.29 ± 1.79) and those without (n = 18; age = 15.98 ± 0.62 years, body mass index = 23.60 ± 2.49) a history of concussion. All athletes underwent a series of HRV recording sessions (1) at rest, (2) while completing a cognitive task at rest, and (3) while completing a cognitive task after a bout of submaximal aerobic exercise. Time-domain measures of HRV, including mean NN intervals, SD of NN intervals, and root mean square of successive NN interval differences, were quantified for each assessment. No differences in characteristics were evident between groups. No between-groups differences in HRV at rest were observed. However, during the cognitive task at rest and after aerobic exercise, athletes with a history of concussion demonstrated a higher SD of NN intervals (78.1 ± 4.3 versus 63.2 ± 4.1 milliseconds and 71.2 ± 4.3 versus 65.2 ± 3.8 milliseconds, respectively; F1,31 = 4.31, P = .046) and root mean square of successive NN interval differences (75.8 ± 6.0 versus 59.0 ± 5.6 milliseconds and 74.0 ± 5.5 versus 59.0 ± 5.2 milliseconds, respectively; F1,31 = 4.88, P = .04) than athletes without a history of concussion. Concussive injuries may result in long-term cardio-autonomic dysfunction. These deficits may not be present at rest but may be triggered by physiological stress.

Can Physical Exercise Attenuate Heart Rate Variability Decline Produced By Cancer?

As cancer therapies have evolved, survival rates have increased, yet side-effects still exist. Cardiotoxicity and neurotoxicity have negative effects on the autonomic nervous system and create cardiovascular dysfunction. Heart rate variability (HRV), a marker of autonomic modulation, negatively decreases with cancer, and is associated with fatigue, depression, and mortality. Exercise appears to attenuate the decline in HRV. PURPOSE: This review analyzes the effects of exercise programs on HRV of cancer patients and survivors. METHODS: PRISMA guidelines were followed by searching Web of Science articles and PubMed databases. The quality of the articles was assessed by PEDro scale. Statistical procedures used Revman 5.3. RESULTS: Six studies fulfilled the inclusion/exclusion criteria and included 272 participants, 30 to 75 years old. Exercise programs had a mean length of 10.4 wks, a frequency of 3.1 d/wk, and a mean duration of 78 min/session. In the time domain HRV measures, exercise increased in Standard deviation of NN intervals (p < 0.00001; MD = 12.79 ms [95% CI = 9.03 to 16.55]) and decreased Root mean square of successive RR interval differences (p = 0.002; MD = 13.08 ms [95% CI = 4.90 to 21.27]) compared to controls. Frequency domain data reveal that significant differences between control and exercise groups could be reached in low-frequency (absolute power: p < 0.0001; SMD = 0.97 [95% CI = 0.61 to 1.34]; relative power: p = 0.04; MD = -7.70 [95%CI = -15.4 to -0.36]) high-frequency (absolute power: p = 0.001, SMD = 1.49 [95% CI = 0.32 to 2.66]; relative power: p = 0.04, MD = 8.00 nu [95% CI = 0.20 to 15.80]) and HF/LF ratio (p = 0.007; MD = -0.32 [95% CI = -0.55 to -0.09). CONCLUSIONS: Exercise programs can lead to positive effects on HRV of cancer patients and survivors, with more positive changes realized with resistance and endurance workouts. However, the overall small sample size studying exercise and HRV in cancer patients warrants further study to confirm these results.

Assessment of heart rate variability (HRV) in subjects with type 2 diabetes mellitus with and without diabetic foot: correlations with endothelial dysfunction indices and markers of adipo-inflammatory dysfunction

BackgroundSome studies have suggested that patients with diabetes and foot complications have worse cardiovascular and cerebrovascular risk profiles, higher degrees of endothelial dysfunction and arterial stiffness and a higher inflammatory background than patients with diabetes without diabetic foot complications. Patients with diabetes mellitus have an alteration in the sympathovagal balance as assessed by means of heart rate variability (HRV) analysis, which is also related to the presence of endothelial dysfunction. Other studies suggest a possible role of inflammation coexisting with the alteration in the sympathovagal balance in favor of the atherosclerotic process in a mixed population of healthy subjects of middle and advanced age.AimsThe aim of this study was to evaluate the degree of alteration of sympathovagal balance, assessed by HRV analysis, in a cohort of patients with diabetes mellitus with diabetic foot and in control subjects without diabetic foot compared with a population of healthy subjects and the possible correlation of HRV parameters with inflammatory markers and endothelial dysfunction indices.MethodsWe enrolled all patients with diabetic ulcerative lesions of the lower limb in the Internal Medicine with Stroke Care ward and of the diabetic foot outpatient clinic of P. Giaccone University Hospital of Palermo between September 2019 and July 2020. 4-h ECG Holter was performed. The following time domain HRV measures were analyzed: average heart rate, square root of the mean of successive differences of NN (RMSSD), standard deviation or square root of the variance (SD), and standard deviation of the means of the NN intervals calculated over a five-minute period (SDANN/5 min). The LF/HF ratio was calculated, reactive hyperemia was evaluated by endo-PAT, and serum levels of vaspine and omentin-1 were assessed by blood sample collection.Results63 patients with diabetic foot, 30 patients with diabetes and without ulcerative complications and 30 patients without diabetes were enrolled. Patients with diabetic ulcers showed lower mean diastolic blood pressure values than healthy controls, lower MMSE scores corrected for age, lower serum levels of omentin-1, lower RHI values, higher body weight values and comparable body height values, HF% and LF/HF ratio values. We also reported a negative correlation between the RHI value and HRV indices and the expression of increased parasympathetic activity (RMSDD and HF%) in subjects with diabetic foot and a statistically significant positive correlation with the LF/HF ratio and the expression of the sympathovagal balance.DiscussionPatients with diabetic foot show a higher degree of activation of the parasympathetic system, expressed by the increase in HF values, and a lower LF/HF ratio. Our findings may corroborate the issue that a parasympathetic dysfunction may have a possible additive role in the pathogenesis of other vascular complications in subjects with diabetic foot.

Effect of short-term mental stress on time- domain indices of heart rate variability in obese individuals – A case- control study

&#x0D; Introduction and Aim: Mental stress may impact dramatically on dynamic autonomic control on heart. Many studies have demonstrated association of high body mass index (BMI) with greater risk for cardiovascular disease with disturbance in autonomic neuronal activity. Analysis of Heart rate variability (HRV)during acute mental stress assesses the autonomic status of the individual. Hence, we aimed to study the effect of acute mental stress on time domain measures in obese adults.&#x0D; &#x0D; Materials and Methods:Sixty male volunteers of 30 each in study group (obese individuals) and control group (non-obese individuals) were recruited for the study. A basal recording of ECG in lead II was done on all the individuals. Then they underwent mental arithmetic stress task for 5 minutes during which again ECG was recorded. The change in time domain measures of HRV during rest and stress task was analyzed and compared between both the groups.&#x0D; &#x0D; Results: Analysis of time domain measures of HRV revealed a statistically significant increase (p ? 0.001) in mean heart rate in both obese and non-obese individuals, while rMSSD(root mean square differences of successive RR interval) and SDNN (standard deviation of all NN intervals) showed a statistically significant (p? 0.001) decrease in obese individuals and non-obese individuals did not show any statistically significant change during the mental stress task.&#x0D; &#x0D; Conclusion: In response to acute mental stress there was increased heart rate in both the groups. But the autonomic neuronal activity differed by way of sympathetic dominance in non-obese individuals and parasympathetic withdrawal in obese individuals.&#x0D;

Association of salivary steroid hormones and their ratios with time-domain heart rate variability indices in healthy individuals.

BackgroundStress system consists of the hypothalamicpituitary-adrenal (HPA) axis and the locus caeruleus/norepinephrine-autonomic nervous system (ANS). Traditionally, HPA axis activity is evaluated by measuring its end-product cortisol, while the activity of ANS is assessed using heart rate variability (HRV) indices. Alterations in cortisol levels and HRV measures during laboratory-based stress tasks were extensively studied in previous research. However, scarce data exist on the associations of HRV measures with the levels of other adrenal steroid hormones under baseline conditions. Thus, we aimed to evaluate the activity of the HPA axis by measuring salivary cortisol, cortisone, dehydroepiandrosterone (DHEA) levels, and their ratios and to examine its association with HRV measures in a sample of healthy young and middle-aged adults.MethodsFor each participant (n=40), three data collection sessions taking place at the same time of the day were scheduled within five working days. Participants completed a self-reported questionnaire on sociodemographic and lifestyle characteristics, filled out t h e Perceived Stress Scale and State-Trait Anxiety Inventory. Also, saliva samples were collected, and physiological measures, including resting HR and HRV, were recorded during three data collection sessions.ResultsStatistically significant associations between diminished parasympathetic vagal tone evaluated by time domain HRV measures and higher salivary cortisol, lower DHEA levels, as well as decreased DHEA to cortisol ratio, were found. Also, physiological stress indicators (i.e., HRV) showed greater intraindividual stability compared with biochemical biomarkers (i.e., salivary steroid hormones) within five days.ConclusionsOur findings suggest that both cortisol and DHEA mediate the link between two stress-sensitive homeostatic systems.

Heart Rate Variability in Children With Autism Spectrum Disorder and Associations With Medication and Symptom Severity.

Decreased heart rate variability (HRV) is considered a common marker of autonomic dysfunction that contributes to poor health outcomes. While some studies have suggested that children with autism spectrum disorder (ASD) show reduced HRV, research is yet to consider whether this may be associated with medication use and symptom severity. This study examined the relationship between resting state HRV, medication use and symptom severity in children diagnosed with ASD. Children with ASD (N = 86), aged between 3 and 12 years (M = 8.09), were compared to 44 neurotypical children of similar age (M = 7.15). Laboratory assessment of HRV involved 5 min of non-invasive baseline electrocardiogram assessments while participants viewed an age-appropriate non-verbal animated video. Time-domain and frequency-domain HRV measures were analyzed. ASD symptom severity was assessed using the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2) and Social Responsiveness Scale (SRS-2). Results indicated that children with ASD exhibited reduced resting HRV relative to neurotypical children. Subsequent analyses within the ASD group suggested that this group difference was greater in children who were taking psychotropic medication (N = 36). Our data also provides tentative evidence of a relationship between HRV and social impairment symptoms in children with ASD, with more severe repetitive behaviors (as measured by the ADOS-2) associated with decreased resting HRV. Overall, these findings suggest that HRV may be atypical in children with ASD and suggest the importance of exploring HRV as a risk factor for cardiovascular health in this group. LAY SUMMARY: Cardiac activity, such as heart rate variability (HRV), can provide insight into the autonomic nervous system. This study reports on the association between resting-state HRV and autonomic nervous system activity in young children with autism spectrum disorder (ASD) compared to neurotypical children. These results may help us understand what underlies autonomic nervous system dysfunction and the potential pathophysiological mechanisms leading to increased cardiovascular risk in ASD.

Abstract 13369: Sympathovagal Imbalance Decades After Atrial Septal Defect Repair

Introduction: Heart rate variability (HRV), a measure of the autonomic nervous system activity, is a morbidity and mortality predictor. HRV is decreased in children with atrial septal defects (ASD) indicating parasympathetic withdrawal and sympathetic predominance, and increased right atrial end-diastolic pressure is believed to influence the sympathovagal balance. Despite the belief of a benign long-term outcome after closure, ASD patients have increased mortality rates after the age of 30 yrs. This may correlate to HRV, why we study HRV in adults after closure. Hypothesis: ASD patients have impaired HRV after closure when compared with controls. Methods: Surgically closed ASD patients (n=17, mean age 32±9 yrs., mean time since closure 19±8 yrs.), percutaneously closed ASD patients (n=18, mean age 28±7 yrs., mean time since closure 15±5 yrs.) and age- and gender-matched controls (n=15, mean age 30±9 yrs.) underwent a 48-hr Holter monitoring. Inclusion criteria were an age of minimum 2 yrs. at the time of diagnosis and minimum 3 yrs. must have passed since ASD closure. The following time-domain HRV measures were analyzed: SD of NN intervals (SDNN), SD of the average NN interval for each 5-minute segment, mean of the SDs of all NN intervals for each 5-minute (SDNNi), root mean square of successive RR interval differences (RMSSD), percentage of successive RR intervals that differ by &gt;50 ms (pNN50), and triangular index. Results: Surgically closed ASD patients have an impairment of all time-domain parameters, while transcatheter closed patients have an impairment of half the parameters. Conclusion: These novel findings demonstrate a cardiac sympathovagal imbalance in adult patients several yrs. after ASD closure and may potentially explain why we observe a long-term morbidity and mortality increase in ASD patients.

Deep learning with wearable based heart rate variability for prediction of mental and general health

The ubiquity and commoditisation of wearable biosensors (fitness bands) has led to a deluge of personal healthcare data, but with limited analytics typically fed back to the user. The feasibility of feeding back more complex, seemingly unrelated measures to users was investigated, by assessing whether increased levels of stress, anxiety and depression (factors known to affect cardiac function) and general health measures could be accurately predicted using heart rate variability (HRV) data from wrist wearables alone. Levels of stress, anxiety, depression and general health were evaluated from subjective questionnaires completed on a weekly or twice-weekly basis by 652 participants. These scores were then converted into binary levels (either above or below a set threshold) for each health measure and used as tags to train Deep Neural Networks (LSTMs) to classify each health measure using HRV data alone. Three data input types were investigated: time domain, frequency domain and typical HRV measures. For mental health measures, classification accuracies of up to 83% and 73% were achieved, with five and two minute HRV data streams respectively, showing improved predictive capability and potential future wearable use for tracking stress and well-being.

Age and Sex Differences in Heart Rate Variability and Vagal Specific Patterns - Baependi Heart Study.

Background:Heart rate variability (HRV) is a noninvasive method for assessing autonomic function. Age, sex, and chronic conditions influence HRV.Objectives:Our aim was to evaluate HRV measures exploring differences by age, sex, and race in a sample from a rural area.Methods:Analytical sample (n = 1,287) included participants from the 2010 to 2016 evaluation period of the Baependi Heart Study, a family-based cohort in Brazil. Participants underwent 24-hour Holter-ECG (Holter) monitoring. To derive population reference values, we restricted our analysis to a ‘healthy’ subset (i.e. absence of medical comorbidities). A confirmatory analysis was conducted with a subgroup sample that also had HRV derived from a resting ECG 10’-protocol obtained during the same time period.Results:The ‘healthy’ subset included 543 participants. Mean age was 40 ± 14y, 41% were male, 74% self-referred as white and mean body-mass-index was 24 ± 3kg/m2. Time domain HRV measures showed significant differences by age-decade and by sex. Higher values were observed for males across almost all age-groups. Parasympathetic associated variables (rMSSD and pNN50) showed a U-shaped distribution and reversal increase above 60y. Sympathetic-parasympathetic balance variables (SDNN, SDANN) decreased linearly by age. Race differences were no significant. We compared time domain variables with complete data (Holter and resting ECG) between ‘healthy’ versus ‘unhealthy’ groups. Higher HRV values were shown for the ‘healthy’ subset compared with the ‘unhealthy’ group.Conclusion:HRV measures vary across age and sex. A U-shaped pattern and a reversal increase in parasympathetic variables may reflect an age-related autonomic dysfunction even in healthy individuals that could be used as a predictor of disease development.

An optimization study of the ultra-short period for HRV analysis at rest and post-exercise

BackgroundUltra-short-term heart rate variability (HRV) analysis (< 5 min) has been extensively growing in the field of exercise performance for autonomic assessment. However, the validation of ultra-short-term HRV was unclear in the recovery period of exercise. This study aimed to elucidate the agreement between ultra-short-term HRV (0–30 s, 0–1 min, 0–2 min, 0–3 min, 0–4 min) and standard short-term HRV (5 min) and to explore the optimal recording duration under rest and post-exercise conditions. Methods69 participants were recruited to perform physical exercise on a treadmill with an intensity of 6 km/h, 9 km/h and 12 km/h, independently. The standard deviation of RR-interval (SDNN) and root mean square of successive differences of RR-intervals (RMSSD) were calculated by using ultra-short periods and standard period at rest condition (Pre-E) and three post-exercise trials, i.e., Post-E1, Post-E2 and Post-E3, respectively. One-way ANOVA with repeated-measures and Cohen's d statistics were conducted, and Bland-Altman analysis and interclass correlation coefficients (ICC) were used to assess the levels of agreement. ResultsFor SDNN and RMSSD, the results of agreement analysis at rest condition were different from those at post-exercise. At Pre-E, SDNN and RMSSD were reliable for ultra-short-term HRV analysis at all ultra-short periods, i.e., 0–30 s, 0–1 min, 0–2 min, 0–3 min and 0–4 min, with most ICCs greater than 0.9 and Cohen's d showing trivial differences (Cohen's d = 0.024–0.117). However, at post-exercise, SDNN0–30s, SDNN0-1min, RMSSD0–30s and RMSSD0-1min showed significant differences with SDNN5min and RMSSD5min, respectively (p < 0.01), and the ICCs was not perfect (< 0.9). HRV analysis with time duration longer than 2 min showed nearly perfect reliability in all post-exercise trials, with trivial differences (Cohen's d = −0.003–0.110) and perfect ICCs (ICCs = 0.916–0.998). Furthermore, the limits of the agreement became tighter as the period duration increased in Bland-Altman plots. ConclusionsThis study demonstrated that ultra-short-term HRV analysis was a good surrogate of standard HRV time-domain measures to reflect the autonomic regulation at rest and post-exercise. Specifically, ultra-short-term HRV0–30s or HRV0-1min was recommended at rest condition, whereas longer than 2 min recording period was reliable to obtain SDNN and RMSSD for the accuracy of HRV analysis.