Time-domain Heart Rate Variability Parameters Research Articles

Heart Rate Variability for Supplementing Withdrawal Assessment in Patients with Opioid Dependence: An Exploratory Study.

Management of opioid dependence requires titrating medication doses based on withdrawal symptoms, but its clinical assessment presents challenges when it comes to subjective reporting. This study aimed to find out the relationship between heart rate variability (HRV) and opioid withdrawal in patients with opioid dependence. Three groups of adult males were recruited: (a) patients with opioid dependence undergoing inpatient detoxification, (b) patients with opioid dependence stabilized on buprenorphine-based opioid substitution treatment, and (c) healthy controls. Frequency and time-domain parameters of HRV were used in the analysis. The opioid withdrawal was assessed using the Subjective Opiate Withdrawal Scale (SOWS). Resting heart rate was found to be significantly different across the three groups (higher in patients stabilized on buprenorphine than the other two groups). In time-domain parameters, the detoxification group had the highest beat-to-beat variability. In frequency-domain parameters, the total power was highest for the detoxification group and lowest for the opioid substitution treatment group. In contrast, the relative power of frequency bands (very low, low, and high) did not vary across the groups at baseline. The SOWS had a weak negative correlation with root mean square of successive differences (RMSSD) in the opioid substitution group and did not have any relationship with HRV parameters in the detoxification group. This exploratory study did not find HRV parameters to be robustly associated with subjective withdrawal, except for a negative association with the beat-to-beat variability among patients on opioid substitution treatment. This study adds to information on HRV in patients with opioid dependence.

Relevance of high glycaemic index breakfast for heart rate variability among collegiate students with early and late chronotypes

ABSTRACT Plasma glucose spikes affect cardiac autonomic modulation resulting in a decrease of heart rate variability (HRV). We hypothesize that a later chronotype or a higher morning plasma melatonin level is associated with larger decreases of HRV following an early high glycaemic index (GI) breakfast. In persons with an early (n = 21) or a late (n = 15) chronotype who consumed a high GI breakfast at 7 a.m. glucose data were continuously monitored. Time domain HRV parameters were calculated from blood volume pulses derived by wireless wrist worn multisensor. HRV changes (values after minus values before breakfast) were associated with chronotype by multivariable linear regression adjusted for age, sex and baseline levels. Morning plasma melatonin levels were determined from samples drawn on the run-in day. Time domain parameters indicate a higher HRV before high GI breakfast in both chronotypes. A later chronotype tended to be associated with smaller decreases of mean interbeat intervals (p = 0.08) only; no associations were seen with morning melatonin levels. This exploratory analysis in a small sample provides a first indication that in young healthy adults later chronotype might be associated with reduced ANS activation following a high GI breakfast. Future studies should elucidate whether this indicates parasympathetic or sympathetic inhibition.

Variabilidad de la frecuencia cardiaca en caninos saludables, adultos, y residentes en hipoxia hipobárica (Bogotá, 2600 metros sobre el nivel del mar)

Heart rate variability (HRV) refers to beat-to-beat fluctuations in heart rate and represents the neurovegetative and endocrine influence on the heart. In the present study, HRV values were obtained in healthy adult canines of both sexes, residing in the city of Bogotá (2600 meters above sea level). Time-domain and frequency-domain HRV parameters were obtained using 60-minute Holter recordings. The distribution of the data was determined using the Shapiro-Wilk test. The dogs were distributed into two subgroups to study their behaviour in relation to sex and age. ANOVA and Kruskal Wallis tests were used to determine statistical differences. In general, the mean HRV values differ from those reported by other authors in studies at sea level and at lower altitudes. The differences in HRV in relation to sex were significant in the RMSSD and pNN50 parameters. There were no differences in the relationship between HRV and age.

Automatic calculation of the parasympathetic, sympathetic and Baevsky stress indexes provides a more comprehensive assessment of cardiac autonomic modulation

Abstract Background Cardiac autonomic modulation (CAM) is clinically evaluated by measuring the Heart Rate Variability (HRV) parameters, related to sympathetic and parasympathetic efferences to the heart, with linear (L), nonlinear (NL), and time-varying (TV) mathematical methods. Recently, automatic calculation of the parasympathetic (PNSi), sympathetic (SNSi), and Baevsky’s stress (BSTRi) indexes [1,2], integrating some L and NL parameters, has become available for more synthetic assessment of CAM. This study aimed to evaluate in healthy subjects (HS) the normal range of PNSi, SNSi, and BSTRi and their physiological variations during daily activity (ACT) and Non-REM sleep (NREM), taking also into account aging-related changes. Methods 24-hour (H24) Holter ECG recordings of 87 HS, divided into three (Age1, Age2 and Age3) groups (16-34, 35-52, and 53-84 years old, respectively), were retrospectively analyzed with the Kubios software (version 4.0), which automatically calculates the PNSi, SNSi, and BSTRi [1], and time domain (TD), frequency domain (FD), NL and TV HRV parameters. HRV was calculated from H24 and short-term (2 minutes) intervals, selected during ACT and NREM. All HRV calculations were done after "detrending" with the "smooth priors" function (lambda=500). Statistical analysis was performed with SPSS 21. Results Average values of the three indexes and several independent L and NL parameters are summarized in Table 1. Average BSTRi values of each age group were not different between ACT and NREM, whereas significant (p<0.05) increments between Age3 and Age1 (during ACT) and between Age3 and both Age1 and 2 (during NREM and H24) were found. Average SNSi values were slightly above the normality range [1] during ACT, or normal (during NREM and H24). Average PNSi values were within the suggested normality range [1] with minimal aging-related variations. Significant aging-related decrement of the selected TD and FD parameters was found in all analysed conditions. Among NL parameters, the correlation dimension (D2) values showed significant aging-related decrement (H24 and NREM), while H24 and ACT sample entropy (SampEn) was lower in Age1 and Age2, compared with Age3 (p<0.05). An example (H24 analysis of Age3 data) of significant (p<0.01) correlation among the three indexes and the selected independent linear and non-linear parameters is shown in Figure 1. Conclusions In this study, a significant aging-related increment of BSTRi was found in all investigated conditions. PNSi and SNSi were always within the suggested normality range [1]. In spite of the significant changes of linear parameters consistent with the well-known aging-related decrement of HRV, the higher SampEn (and BSTRi) found in Age3 HS suggests that an "healthy elderly", is characterized by a more complex adaptation of CAM, likely mediated also by the observed moderate (healthy?) increment of physiological stress. However further investigation on a broader population is warranted.Table 1Figure 1

Synthetic assessment of cardiac autonomic modulation and Baevsky stress index in patients with synucleinopathies

Abstract Background The Baevsky Stress Index (BSTRi), calculated from Heart Rate Variability (HRV) data, has been proposed for quantitative assessment of physiological stress, with higher scores indicating higher levels of physical and/or psychological stress [1]. Cardiac autonomic modulation can be synthetically quantified by calculating the parasympathetic (PNSi) and the sympathetic (SNSi) indexes. The values of the BSTRi, SNSi, and PNSi in patients with synucleinopathies of different prognoses have not been reported yet. Purpose To quantify, in patients with Parkinson's disease (PD) and Multisystem Atrophy (MSA), the BSTRi, its correlation with the PNSi and the SNSi indexes, and their potential value for a synthetic assessment of cardiac autonomic modulation and early differential diagnosis between PD and MSA. Methods Holter ECG data of 66 patients with Parkinsonian syndromes were retrospectively analyzed after 10 years of follow-up. Out of them, 34 patients with a certain diagnosis of PD (17) and MSA (17) were selected for this study. HRV was analyzed with the Kubios software (version 4.0), providing automatic calculation of the BSTRi, PNSi, and SNSi [2], as well as of time domain (TD), frequency domain (FD), nonlinear (NL), and time-varying (TV) HRV parameters. HRV was calculated from selected short-term intervals (of 5 minutes), during daily activity (ACT5’), and non-REM sleep (NREM5’), and from 24-hours Holter recordings. Patients’ HRV findings were compared with those of 51 age-matched healthy subjects (HS). Results An example of individual automatic graphic summary is shown in Figure 1. Both short-term and 24-hour BSTRi and SNSi values were significantly (p < 0.05) higher in PD and MSA compared to those of HS, in all investigated conditions. Short-term PNSi was significantly higher in HS than in PD in all conditions, but only during NREM5’ in MSA patients (Table 1). No significant difference was found between the indexes of PD and MSA patients. As in HS (R=92), BSTRi was positively correlated with the SNSi in MSA (average R= 0.83 and 0.89 during ACT5’ and NREM5’, respectively), but less evident in PD (R=0.67). The inverse correlation between PNSi and SNSi (R=0.75 in HS) was lost in both MSA and PD. Conclusions Higher values of BSTRi in PD and MSA compared to HS suggest that patients with synucleinopathies do experience higher levels of psychophysiological stress, which may affect their quality of life negatively. However, since no significant difference was found in this study between BSTRi values of PD and MSA patients, BSTRi seems at present unreliable for early differentiation between the two diseases. Telematic assessment of BSTRi, SNSi, and PNSi could be useful for remote monitoring of PD and MSA patients’ psychophysiological stress, to provide timely intervention and adaptive treatment.Fig.1 Example of graphic summary (ACT5')

Influence of shift work on sleep quality and circadian patterns of heart rate variability among nurses.

Shift work implementation is essential for providing continuous patient care in hospitals. However, working in shifts on a routine basis may disrupt the circadian pattern and alter the sleep-wakefulness cycle in nurses. Stress due to shift work can influence the adaptability of the cardiovascular system, produce psychophysiological strain and deteriorate work performance in female nurses. This study investigated the effect of morning and night shift work on sleep quality and circadian patterns governing heart rate variability (HRV) in female nurses working in a tertiary care hospital. Thirty-eight healthy female nurses were recruited. Frequency and time domain parameters of HRV were recorded as markers of cardiac autonomic function. A student t-test was used to investigate differences in HRV between morning and night shift workers. Mann-Whitney non-parametric test was applied for the difference between Pittsburgh Sleep Quality Index (PSQI) scores in the two groups. Standard deviation of the normal-to-normal interval (SDNN) (msec), total power (ms2) and high-frequency (HF) band power (ms2) were significantly reduced in night shift nurses than in morning shift nurses. The low-frequency (LF)/HF ratio was significantly increased in night shift nurses. The differences in standard deviation of the averages of NN intervals (SDaNN) (msec), root mean square of successive differences between adjacent NN intervals (RMSSD), mean NN, very low-frequency (VLF) band power (ms2) and LF band power (ms2) were not statistically significant. The global PSQI score was significantly higher among night shift workers than in morning shifts. Inadequate sleep can disrupt the body's ability to regulate heart rhythm and increase the risk of cardiovascular diseases and mortality. The research suggests a propensity for autonomic imbalance in night shift workers when compared to their counterparts on morning shifts.

Volitionally Regulated Breathing with Prolonged Expiration Influences Food Craving and Impulsivity

Introduction: Previously, an intervention involving volitional slow breathing reduced trait food craving with protective effects on cardiac vagal activity (CVA). Breathing with a low inspiration-to-expiration (i/e) ratio also increases CVA. High CVA was separately associated with low unregulated eating and lesser impulsivity. Hence, the present study assessed breathing with a low i/e for effects on state food craving, hunger and satiety, state impulsivity, and heart rate variability (HRV) in healthy obese persons. Methods: Forty obese persons were randomized to two groups. The intervention group (mean age ± SD, 41.15 ± 12.63, M:F, 10:10) practiced metronome-regulated breathing with low i/e at 12 breaths per minute (expiration 72% of total breath duration) and attained expiration 55.8% of total breath duration, while the active control group (mean age ± SD, 44.45 ± 11.06, M:F, 13:07) sat motionless and directed their gaze and awareness to the stationary metronome without modifying their breath consciously. The HRV was recorded before, during, and after breathing intervention (or control) (standard limb lead I, acquisition at 2,000 Hz, with an LF filter = 0.5 Hz and HF filter = 50 Hz). Time-domain and frequency-domain HRV parameters were obtained with Kubios software. State food craving, and hunger and satiety were recorded before and after the intervention/control. Results: The intervention group decreased total state food craving scores and the sub-domains (i.e., desire to eat, positive reinforcement, lack of control and hunger), increased current satisfaction with food, decreased total state impulsivity (repeated measures ANOVA, p < 0.05 in all cases), increased HF-HRV and RMSSD (linear mixed model analyses with age and gender as fixed factors; p < 0.05 in all cases) during the intervention compared to the preceding baseline. The intervention group also showed an increase in positive mood and a decrease in aroused and negative mood states. Conclusion: Changes in state food craving and impulsivity could be related to an increase in HRV or to changes in subjective relaxation and positive mood or to both.

Abstract P299: Alteration of Cardiac Autonomic Function Through Inhalation of Biogenic Volatile Organic Compounds

Background: There is an inverse relationship between exposure to greenspaces and prevalence of cardiovascular disease and cardiovascular disease risk factors. More specifically, green exposure is associated with electrocardiogram (ECG) changes, suggesting a potential alteration of cardiac autonomic balance. One proposed mechanism by which cardiac autonomic balance may be altered is a direct physiologic effect of inhalable plant derived compounds, or biogenic volatile organic compounds (bVOCs), including limonene, α- and β-pinene which are commonly released from vegetation. Therefore, we examined the relationship between acute exposure of isolated bVOCs and cardiac autonomic tone. Hypothesis: We hypothesize that controlled exposure to isolated individual bVOCs will decrease cardiac sympathetic tone. Methods: Under controlled conditions after a bVOC washout period, healthy adults ages 18-70 were exposed to limonene (n=32), α-pinene (n=24), β-pinene (n=17), and a control (room air, n=9). Exposure consisted of one inhalation every 30 seconds for a total of 5 minutes (10 inhalations total). Pre- and post-exposure measurements of supine heart rate variability (HRV) were conducted following a 10-minute rest period. HRV was analyzed using a clean, 5-minute epoch with &gt;95% effective data length. Statistical analysis was performed using paired t-tests to determine changes in HR and HRV. Significance level was set at p&lt;0.05, a priori . Results: Our population was primarily female (56%, 18 of 32), white (53%, 17 of 32), high income (47%, 15 of 32), and had an education higher than a 4-year degree (62.5%, 20 of 32). There were significant decreases in HR when exposed to limonene (pre: 64.87±9.86bpm vs. post: 63.26±9.10bpm, p&lt;.001) and α-pinene (pre: 63.98±9.32bpm vs. post: 61.64±9.72bpm, p=.008), along with trends seen in β-pinene (pre: 65.78±10.60bpm vs. post: 63.74±9.65bpm, p=.066). Control exposure showed no difference (pre: 65.40±8.38bpm vs. post: 64.14±9.35bpm, p=.301). Normalized low- (LF) and high-frequency (HF) HRV parameters showed no change across isolated bVOCs, however the LF/HF ratio scores decreased significantly following β-pinene exposure (pre: 1.62±1.69 vs. post: 0.96±0.96, p=.039). HRV time-domain parameters RMSSD and SDNN did not change following isolate exposure. Conclusions: Post-exposure decreases in HR and LFHF ratios indicate the potential for cardiovascular disease risk reduction from bVOC exposure leading to decreased sympathetic tone. Additional work is required to determine the mechanism of exposure-related changes.

Effect of Prenatal Yoga versus Moderate-Intensity Walking on Cardiorespiratory Adaptation to Acute Psychological Stress: Insights from Non-Invasive Beat-to-Beat Monitoring.

We recently reported enhanced parasympathetic activation at rest throughout pregnancy associated with regular yoga practice. The present study presents a secondary analysis of data collected within a prospective cohort study of 33 pregnant women practicing yoga once weekly throughout pregnancy and 36 controls not involved in formal pregnancy exercise programs. The objective was to assess the impact of prenatal yoga on the autonomic nervous system stress response. Healthy pregnant women with singleton pregnancies were recruited in the first trimester. There was no significant difference in the maternal body mass index (BMI) between the yoga group and the controls (24.06 ± 3.55 vs. 23.74 ± 3.43 kg/m2, p = 0.693). Women practicing yoga were older (28.6 ± 3.9 vs. 31.3 ± 3.5 years, p = 0.005) and more often nulliparous (26 (79%) vs. 18 (50%), p = 0.001). We studied heart rate variability (HRV) parameters in the time domain (SDNN, standard deviation of regular R-R intervals, and RMSSD, square root of mean squared differences of successive R-R intervals) and frequency domain (ln(LF/HF), natural logarithm of low-frequency to high-frequency power), as well as synchronization indices of heart rate, blood pressure and respiration during and immediately following acute psychological stress of a standardized mental challenge test. Measurements were performed once per trimester before and after yoga or a 30 min moderate-intensity walk. Statistical comparison was performed using three-way analyses of variance (p < 0.05 significant). Time domain HRV parameters during and following mental challenge in the yoga group were significantly higher compared to the controls regardless of the trimester (F = 7.22, p = 0.009 for SDNN and F = 9.57, p = 0.003 for RMSSD, respectively). We observed no significant differences in the yoga group vs. the controls in terms of ln(LF/HF) and synchronization indices. Regular prenatal yoga practice was associated with a significantly reduced sympathetic response to mental challenge and quicker recovery after acute psychological stress. These effects persisted throughout pregnancy with regular practice.

Time-domain heart rate dynamics in the prognosis of progressive atherosclerosis

Background and aimThe regular uptake of a high-fat diet (HFD) with changing lifestyle causes atherosclerosis leading to cardiovascular diseases and autonomic dysfunction. Therefore, the current study aimed to investigate the correlation of autonomic activity to lipid and atherosclerosis markers. Further, the study proposes a support vector machine (SVM) based model in the prediction of atherosclerosis severity. Methods and resultsThe Lead-II electrocardiogram and blood markers were measured from both the control and the experiment subjects each week for nine consecutive weeks. The time-domain heart rate variability (HRV) parameters were derived, and the significance level was tested using a one-way Analysis of Variance. The correlation analysis was performed to determine the relation between autonomic parameters and lipid and atherosclerosis markers. The statistically significant time-domain values were used as features of the SVM. The observed results demonstrated the reduced time domain HRV parameters with the increase in lipid and atherosclerosis index markers with the progressive atherosclerosis severity. The correlation analysis revealed a negative association between time-domain HRV parameters with lipid and atherosclerosis parameters. The percentage accuracy increases from 86.58% to 98.71% with the increase in atherosclerosis severity with regular consumption of HFD. ConclusionsAtherosclerosis causes autonomic dysfunction with reduced HRV. The negative correlation between autonomic parameters and lipid profile and atherosclerosis indexes marker revealed the potential role of vagal activity in the prognosis of atherosclerosis progression. The support vector machine presented a respectable accuracy in the prediction of atherosclerosis severity from the control group.

The Heart's Function as a Pump Assessed via Impedance Cardiography and the Autonomic System Balance in Patients with Early-Stage Acromegaly.

Acromegaly is a rare, chronic disease that involves structural and functional abnormalities of the cardiovascular system. Acromegaly likely affects interactions between the cardiovascular system and the autonomic nervous system (ANS). Therefore, assessing the relationship between sympathetic-parasympathetic balance by analyzing heart rate variability (HRV) and the hemodynamic profile via impedance cardiography (ICG) may be useful in learning the exact nature of interactions between the ANS and the cardiovascular system. The purpose of this study was to assess a possible association between HRV and ICG-based parameters of cardiac function in patients newly diagnosed with acromegaly. This observational cohort study was conducted on 33 patients (18 men, mean age of 47 years) newly diagnosed with acromegaly and no significant comorbidities. A correlation analysis (Spearman's rank coefficient R) of the parameters assessed via ICG and the HRV assessed via 24 h ambulatory electrocardiography was performed. ICG assessments included the following parameters: stroke volume index (SI), cardiac index (CI), acceleration index (ACI), velocity index (VI), and Heather index (HI). The analysis of HRV included both time-domain parameters (pNN50, SDNN, SDSD, rMSSD) and frequency-domain parameters (total power (TP) and its individual frequency bands: low-frequency (LF day/night), high-frequency (HF day/night), and the LF/HF ratio (day/night)). Frequency-domain HRV analysis showed the following correlations: (1) lower nighttime LF values with higher ACI (R = -0.38; p = 0.027) and HI (R = -0.46; p = 0.007) values; (2) higher nighttime HF values with higher ACI (R = 0.39; p = 0.027) and HI (R = 0.43; p = 0.014) values; (3) lower nighttime LF/HF values with higher ACI (R = -0.36; p = 0.037) and HI (R = -0.42; p = 0.014) values; (4) higher nighttime TP values with higher SI values (R = 0.35; p = 0.049). Time-domain parameters of HRV showed a significant correlation only between the nighttime values of SDSD and SI (R = 0.35; p = 0.049) and between the daytime and nighttime values of SDNN and HR (R = -0.50; p = 0.003 and R = -0.35; p = 0.046). In multivariate regression, only ACI was revealed to be independently related to HRV. In patients newly diagnosed with acromegaly, the relationship between the sympathetic-parasympathetic balance assessed via HRV and the hemodynamic profile assessed via ICG was revealed. Better function of the left ventricle was associated with a parasympathetic shift in the autonomic balance.

Comparison of time domain indices of heart rate variability between alcohol-dependent individuals and non-alcoholic subjects

Background: Alcohol dependence develops because of repeated alcohol intake. Alcohol damages the cardiac autonomic nerve fibers leading to autonomic imbalance, resulting in reduced heart rate variability (HRV). HRV refers to the complex beat-to-beat variation in the heart rate, produced by the interplay of sympathetic and parasympathetic neural activity at the Sino-atrial node. Our body works effectively in parasympathetic activity dominance. The time domain indices of HRV are specific markers of parasympathetic activity. A decrease in the time domain parameters indicates reduced parasympathetic activity in the heart, indicating cardiac autonomic dysfunction with vagal neuropathy. Aims and Objectives: The objectives of the study are as follows: (1) To assess the HRV in alcohol-dependent individuals using time domain indices. (2) To compare the HRV between alcoholic-dependent individuals and non-alcoholic subjects. Materials and Methods: A total of 110 individuals in the age group of 20–55 years were recruited for our study. Among them, 55 were alcohol-dependent individuals selected based on the diagnostic and statistical manual-IV, international classification of diseases-10 criteria, and 55 age and gender-matched volunteers were selected as healthy non-alcoholic controls. Short-term HRV was recorded in a supine posture, and the results were interpreted. Statistical analysis was done using the software SPSS version 21.0. Results: Our results showed a significant reduction in the time-domain parameters of HRV – SDNN, RMSSD, NN50, and pNN50 in the alcohol-dependent individuals compared to the controls, suggesting reduced parasympathetic activity in the heart indicating cardiac autonomic neuropathy. Conclusion: Alcohol affects the cardiac autonomic status leading to sudden death due to arrhythmias. HRV can be used as a non-invasive test to assess cardiac autonomic dysfunction and its biofeedback can help alcohol-dependent individuals to adopt healthy lifestyle measures.

Unveiling the acute neurophysiological responses to strength training: An exploratory study on novices performing weightlifting bouts with different motor learning models.

Currently, there is limited evidence regarding various neurophysiological responses to strength exercise and the influence of the adopted practice schedule. This study aimed to assess the acute systemic effects of snatch training bouts, employing different motor learning models, on skill efficiency, electric brain activity (EEG), heart rate variability (HRV), and perceived exertion as well as mental demand in novices. In a within-subject design, sixteen highly active males (mean age: 23.13 ± 2.09 years) randomly performed snatch learning bouts consisting of 36 trials using repetitive learning (RL), contextual interference (blocked, CIb; and serial, CIs), and differential learning (DL) models. Spontaneous resting EEG and HRV activities were recorded at PRE and POST training bouts while measuring heart rate. Perceived exertion and mental demand were assessed immediately after, and barbell kinematics were recorded during three power snatch trials performed following the POST measurement. The results showed increases in alpha, beta, and gamma frequencies from pre- to post-training bouts in the majority of the tested brain regions (p values ranging from < 0.0001 to 0.02). The CIb model exhibited increased frequencies in more regions. Resting time domain HRV parameters were altered following the snatch bouts, with increased HR (p < 0.001) and decreased RR interval (p < 0.001), SDNN, and RMSSD (p values ranging from < 0.0001 to 0.02). DL showed more pronounced pulse-related changes (p = 0.01). Significant changes in HRV frequency domain parameters were observed, with a significant increase in LFn (p = 0.03) and a decrease in HFn (p = 0.001) registered only in the DL model. Elevated HR zones (> HR zone 3) were more dominant in the DL model during the snatch bouts (effect size = 0.5). Similarly, the DL model tended to exhibit higher perceived physical (effect size = 0.5) and mental exertions (effect size = 0.6). Despite the highest psycho-physiological response, the DL group showed one of the fewest significant EEG changes. There was no significant advantage of one learning model over the other in terms of technical efficiency. These findings offer preliminary support for the acute neurophysiological benefits of coordination-strength-based exercise in novices, particularly when employing a DL model. The advantages of combining EEG and HRV measurements for comprehensive monitoring and understanding of potential adaptations are also highlighted. However, further studies encompassing a broader range of coordination-strength-based exercises are warranted to corroborate these observations.

The 24-Hour Cardiac Autonomic Activity in Patients With Allergic Rhinitis.

Definitive knowledge of the 24-hour cardiac autonomic activity in patients with allergic rhinitis (AR) is lacking. Thus, we aimed to evaluate heart rate variability (HRV), which is used to measure cardiac autonomic activity by 24-hour Holter monitoring in patients with AR. We enrolled 32 patients who visited our clinic and were diagnosed with AR. The control group was selected four-fold (n = 128) by matching (age, sex, hypertension, and diabetes) in the AR group from a Holter registry in the cardiology department. The HRV results, which were measured using 24-hour Holter monitoring, were compared between the AR and control groups. All time-domain parameters of HRV revealed no differences between the groups. However, among the frequency domain parameters of HRV, the low-frequency to high-frequency ratio and low-frequency power in normalized units were significantly lower in the AR group. Conversely, high-frequency power in normalized units was significantly higher in the AR group. In the multiple regression analysis, AR was independently associated with sympathetic withdrawal (adjusted odds ratio = 3.393, P = 0.020) after adjusting for age, sex, hypertension, diabetes mellitus, and hyperlipidemia. The present findings suggest differences in cardiac autonomic activity which are related with sympathetic withdrawal in patients with AR compared with that in the normal population over 24 hours.

Anthracycline's Effects on Heart Rate Variability in Children with Acute Lymphoblastic Leukemia: Early Toxicity Signs-Pilot Study.

Anthracycline treatments are known to cause cardiotoxic long-term side effects in cancer survivors. Recently, a decrease in heart rate variability (HRV) has been identified in these patients, signaling autonomic dysfunction and altered cardiac fitness. This study aimed at evaluating changes in HRV in children treated with anthracyclines. A total of 35 pediatric patients with acute lymphoblastic leukemia were evaluated by means of a 24 h Holter ECG, at baseline and after reaching half the total cumulative dose of doxorubicin equivalent (120 mg/m2). Parameters of HRV were assessed, as well as any arrhythmic episodes, bradycardia and tachycardia percentages. The results showed a significant decrease in both time-domain and frequency-domain HRV parameters, following anthracycline treatment. The low-frequency (LF) to high-frequency (HF) parameters' ratio also displayed a significant difference (p = 0.035), suggestive of early cardiac autonomic dysfunction. Of note, none of the patients presented symptoms of heart disease or elevated troponins, and only two patients presented echocardiographic signs of diastolic dysfunction. The present study showed that cardiac autonomic nervous system regulation is compromised in children treated with anthracyclines even before reaching the total cumulative dose. Therefore, HRV parameters could be the first indicators of subclinical cardiac toxicity, making Holter ECG monitoring of the oncological patient a necessity.

Wrist-Worn Sensor Validation for Heart Rate Variability and Electrodermal Activity Detection in a Stressful Driving Environment.

Wearable sensors are widely used to gather psychophysiological data in the laboratory and real-world applications. However, the accuracy of these devices should be carefully assessed. The study focused on testing the accuracy of the Empatica 4 (E4) wristband for the detection of heart rate variability (HRV) and electrodermal activity (EDA) metrics in stress-inducing conditions and growing-risk driving scenarios. Fourteen healthy subjects were recruited for the experimental campaign, where HRV and EDA were recorded over six experimental conditions (Baseline, Video Clip, Scream, No-Risk Driving, Low-Risk Driving, and High-Risk Driving) and by means of two measurement systems: the E4 device and a gold standard system. The overall quality of the E4 data was investigated; agreement and reliability were assessed by performing a Bland-Altman analysis and by computing the Spearman's correlation coefficient. HRV time-domain parameters reported high reliability levels in Baseline (r > 0.72), Video Clip (r > 0.71), and No-Risk Driving (r > 0.67), while HRV frequency domain parameters were sufficient in Baseline (r > 0.58), Video Clip (r > 0.59), No-Risk (r > 0.51), and Low-Risk Driving (r > 0.52). As for the EDA parameters, no correlation was found. Further studies could enhance the HRV and EDA quality through further optimizations of the acquisition protocol and improvement of the processing algorithms.

Best Parameters of Heart Rate Variability for Assessing Autonomic Responses to Brief Rectal Distention in Patients with Irritable Bowel Syndrome.

Heart rate variability (HRV) has been used to measure autonomic nervous system (ANS) activity noninvasively. The purpose of this study was to identify the most suitable HRV parameters for ANS activity in response to brief rectal distension (RD) in patients with Irritable Bowel Syndrome (IBS). IBS patients participated in a five-session study. During each visit, an ECG was recorded for 15 min for baseline values and during rectal distension. For rectal distension, a balloon was inflated in the rectum and the pressure was increased in steps of 5 mmHg for 30 s; each distension was followed by a 30 s rest period when the balloon was fully deflated (0 mmHg) until either the maximum tolerance of each patient was reached or up to 60 mmHg. The time-domain, frequency-domain and nonlinear HRV parameters were calculated to assess the ANS activity. The values of each HRV parameter were compared between baseline and RD for each of the five visits as well as for all five visits combined. The sensitivity and robustness/reproducibility of each HRV parameter were also assessed. The parameters included the Sympathetic Index (SI); Root Mean Square of Successive Differences (RMSSD); High-Frequency Power (HF); Low-Frequency Power (LF); Normalized HF Power (HFn); Normalized LF Power (LFn); LF/HF; Respiratory Sinus Arrhythmia (RSA); the Poincare Plot's SD1, SD2 and their ratio; and the pNN50, SDSD, SDNN and SDNN Index. Data from 17 patients were analyzed and compared between baseline and FD and among five sessions. The SI was found to be the most sensitive and robust HRV parameter in detecting the ANS response to RD. Out of nine parasympathetic parameters, only the SDNN and SDNN Index were sensitive enough to detect the parasympathetic modulation to RD during the first visit. The frequency-domain parameters did not show any change in response to RD. It was also observed that the repetitive RD in IBS patients resulted in a decreased autonomic response due to habituation because the amount of change in the HRV parameters was the highest during the first visit but diminished during subsequent visits. In conclusion, the SI and SDNN/SDNN Index are most sensitive at assessing the autonomic response to rectal distention. The autonomic response to rectal distention diminishes in repetitive sessions, demonstrating the necessity of randomization for repetitive tests.

A Serious Game to Self-Regulate Heart Rate Variability as a Technique to Manage Arousal Level Through Cardiorespiratory Biofeedback: Development and Pilot Evaluation Study.

Heart rate variability biofeedback (HRVB) is an established intervention for increasing heart rate variability (HRV) in the clinical context. Using this technique, participants become aware of their HRV through real-time feedback and can self-regulate it. The aim of this study was 2-fold: first, to develop a serious game that applies the HRVB technique to teach participants to self-regulate HRV and, second, to test the app with participants in a pilot study. An HRVB app called the FitLab Game was developed for this study. To play the game, users must move the main character up and down the screen, avoiding collisions with obstacles. The wavelength that users must follow to avoid these obstacles is based on the user's basal heart rate and changes in instantaneous heart rate. To test the FitLab Game, a total of 16 participants (mean age 23, SD 0.69 years) were divided into a control group (n=8) and an experimental group (n=8). A 2 × 2 factorial design was used in each session. Participants in the experimental condition were trained in breathing techniques. Changes in the frequency and time domain parameters of HRV and the game's performance features were evaluated. Significant changes in the average RR intervals and root mean square of differences between adjacent RR intervals (RMSSD) were found between the groups (P=.02 and P=.04, respectively). Regarding performance, both groups showed a tendency to increase the evaluated outcomes from baseline to the test condition. The results may indicate that playing different levels leads to an improvement in the game's final score by repeated training. The tendency of changes in HRV may reflect a higher activation of the mental system of attention and control in the experimental group versus the control group. In this context, learning simple, voluntary strategies through a serious game can aid the improvement of self-control and arousal management. The FitLab Game appears to be a promising serious game owing to its ease of use, high engagement, and enjoyability provided by the instantaneous feedback.

Effects of high intensity interval-based inspiratory muscle training in patients with heart failure: A single-blind randomized controlled trial

BackgroundGiven the promising effects of inspiratory muscle training (IMT), determining the most appropriate IMT protocol will optimize the training benefits. ObjectivesThe objective of this study was to determine the effects of high intensity interval-based inspiratory muscle training (H-IMT) on cardiovascular, pulmonary, physical, and psychosocial functions in patients with heart failure and reduced ejection fraction (HFrEF). MethodsThirty-four patients with HFrEF were randomly assigned to the H-IMT or control group for 3 days/week, 8 weeks training period. The H-IMT group performed IMT at least 70% of the maximal inspiratory pressure, whereas the control group performed unloaded IMT. Each session occurred 7 sets with a total of 21 min consisting of 2-min training and 1-min interval. Heart rate variability (HRV), arterial stiffness, respiratory muscle strength and endurance, diaphragm thickness, quadriceps strength, functional capacity, frailty, dyspnea, fatigue, disease-specific health-related quality of life (HRQoL), and generic HRQoL were evaluated at baseline and after 8 weeks training period by blinded assessors. ResultsStatistically significant between-group differences were observed in the time domain parameters of HRV, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific HRQoL in favor of the H-IMT group (p<0.05). ConclusionsH-IMT is an effective protocol for improving cardiac autonomic function, arterial stiffness, inspiratory and quadriceps muscle strength, respiratory muscle endurance, diaphragm thickness, functional capacity, frailty, dyspnea, fatigue, and disease-specific quality of life in patients with HFrEF. Clinical trial registrationNCT04839211

Effects of Three-Hour Wearing Personal Protective Equipment on Heart Rate Variability in Healthcare Workers for the Treatment of COVID-19 Patients.

Personal protective equipment (PPE), an essential shield to protect healthcare workers (HCWs) during the COVID-19 pandemic, has been reported to affect their heart rate variability (HRV). To investigate the changes of very short-term heart rate variability in HCWs after three hours of wearing PPE to treat COVID-19 patients at different working times and intensities, and related factors. Sixty-five healthy HCWs were enrolled at the Number 2 Infectious Field Hospital (formed by Military Hospital 103), Vietnam. Two-minute 12-lead electrocardiograms were recorded before wearing and after removing PPE. After three hours of wearing PPE, the mean heart rate of HCWs increased (p = 0.048) meanwhile, the oxygen saturation decreased significantly (p = 0.035). Standard deviation of all normal to normal intervals (SDNN), mean intervals RR (mean NN), and root mean square successive difference (rMSSD) after wearing PPE was also reduced significantly. SDNN, Mean NN, and rMSSD decreased as the working intensity increased (as in mild, moderate, and severe patient departments). In univariate regression analysis, logSDNN, logmean NN and logrMSSD were positively correlated with SpO2 and QT interval (r = 0.14, r = 0.31, r = 0.25; r = 0.39, r = 0.77, r = 0.73, respectively) and were negatively correlated with ambient temperature inside PPE (r = -0.41, r = -0.405, r = -0.25, respectively) while logmean NN and log rMSSD were negatively correlated with diastolic blood pressure (r = -0.43, r = -0.39, respectively). In multivariable regression analysis, logSDNN and logmean NN were negatively correlated to ambient temperature inside PPE (r = -0.34, r = -0.18, respectively). Time-domain heart rate variability decreased after wearing PPE. Time-domain HRV parameters were related to ambient temperature inside PPE, diastolic blood pressure, QT interval, and SpO2.