Assessment Of Heart Rate Variability Research Articles

Loneliness during the post-confinement period: The significance of social living conditions for stress biomarkers and memory

In the aftermath of the COVID-19 lockdown, concerns about the impact of loneliness and reduced social interactions on mental health have arisen. This study explored the repercussions of post-lockdown social restrictions across psychological (loneliness, perceived stress, and depressive symptoms), biological (hair cortisol and cardiovascular activity), and cognitive dimensions (subjective memory complaints and working, declarative, and prospective memory), with a specific emphasis on perceived loneliness and the living situation. The study included 45 students: 23 (mean age = 25.69 years) in the Alone Group (AG), who experienced significant family changes and international relocation, and 22 (mean age = 25.50 years) in the Not Alone Group (NAG), who maintained their nuclear family and did not move from their home country. We assessed heart rate variability (HRV) before, during, and after immediate memory evaluations using time-domain (the square root of the mean, RMSSD) measures. The analysis revealed no significant group differences in telematic contact with family and friends, perceived stress, or depression. However, the AG participants reported fewer face-to-face interactions and greater perceived loneliness compared to the NAG. Additionally, the AG group exhibited slightly higher hair cortisol levels and worse working memory (WM) and prospective memory (PM) performance. Importantly, no significant associations were observed between memory outcomes and stress biomarkers. However, a significant interaction effect of loneliness in the relationship between hair cortisol levels and PM was found. That is, hair cortisol concentrations were negatively related to PM when participants perceived high and moderate loneliness. This interaction was absent in the working and declarative memory domains. In summary, these findings underscore the intricate interplay between loneliness, cortisol, and memory, emphasizing the need for comprehensive research on the complex mechanisms governing these multifaceted relationships.

Multimodal coupling and HRV assessment characterize autonomic functional changes in congestive heart failure patients with sinus rhythm or severe arrhythmia

Autonomic nervous system (ANS) dysfunction is a significant characteristic of patients with congestive heart failure (CHF). Respiratory sinus arrhythmia (RSA) serves as an index of parasympathetic nervous system (PNS) function usually quantified by the high-frequency power of heart rate variability (HRV). However, the high breathing rate of CHF patients results in deviations when estimating RSA by HRV. Multimodal coupling analysis (MMCA) is a novel method of quantifying RSA which decomposes the R-R signal adaptively into intrinsic mode functions (IMFs) followed by identification of the RSA-related IMF. MMCA also calculates the phase synchronization between RSA-related IMF and respiratory signals to exclude the influences that are unrelated to RSA. In this study, we introduced HRV and MMCA-derived parameters to quantify ANS function for CHF patients, along with their comparisons in the clinical efficacy evaluation. Thirty-seven CHF patients were recruited, including 17 with sinus rhythm (SRHF) and 20 with severe arrhythmia (ARHF). Our results showed that all parameters for SRHF patients increased after treatment except for LF/HF. Only LF/HF, α2, and MMCA-derived RSA showed significant differences after treatment for ARHF patients, wherein the MMCA-derived RSA significantly decreased regardless of the left ventricular ejection fraction. The PNS function and ANS balance were recovered in all the CHF patients after treatment. Metrics including MeanRR, SDRR, LF, HF, TPower, SD1, SD2, and MMCA-derived RSA showed more significant improvements in SRHF patients whose New York Heart Association functional class improved after treatment. These metrics can be used to guide prognosis and therapeutic efficacy monitoring.

Assessing Heart Rate Variability in Patients with CKD: Association with Vascular Dysfunction

Assessing Heart Rate Variability in Patients with CKD: Association with Vascular Dysfunction

Heart Rate Variability as a Predictor of Daytime Sleepiness During Prolonged Isolation

The 120-day isolation experiment (SIRIUS-19 program) within the SIRIUS project (http://sirius.imbp.ru/) involved 6 volunteers aged 28 to 44 years (three men and three women). Research methods included daily ECG registration to assess heart rate variability, blood pressure measurement and self-assessment of sleep quality over the past night using a visual analogue scale. The studies were carried out in the morning after waking up. Once a week in the evening (17.00–19.00), volunteers filled out a scale of clinical daytime sleepiness self-assessment, which allows evaluate the subjective condition over the past day. During the regression analysis, the possibility of predicting the appearance of daytime sleepiness in terms of cardiac activity was assessed. It was found, that the heart rate, blood pressure and heart rate variability indicators recorded in the morning time make it possible to measure the quality of past sleep and predict the level of subsequent daytime sleepiness. We assume that the increased activity of the parasympathetic branch of the autonomic nervous system in the morning characterizes both the previous lack of sleep and the risk of developing sleep inertia and daytime sleepiness in general.

A wearable device based on the ionic liquid decorated sponge-like ultraviolet-curable resin for recognizing human mental health conditions

Developing a wearable device that can reliably and continuously detect human pulse signals and assess heart rate variability (HRV) parameters is essential for discriminating healthy subjects from patients with cardiovascular diseases and mental health disorders. Here, by combining a template-assisted ultraviolet-curing method with a subsequent ionic liquid modification, we propose a sponge-like dielectric layer and adopt it to construct a wearable device for decoding human mental health conditions. Benefiting from the coexisting sponge-like structures and an ionic liquid, the proposed wearable device presents a robust capacitance response, and could continuously monitor human pulse signals as well as analyze inter-beat intervals (IBIs) and HRV parameters of volunteers under different emotional states. Lastly, IBIs distributions and heart rates extracted from the pulse signals of the volunteers with different emotional conditions are employed as input features to train a machine-learning model, which is performed to further demonstrate the possibility of recognizing human emotions via pulse signal analysis. In conclusion, by incorporating the proposed wearable device with a machine-learning model, it is expected to achieve the emotional recognition of the volunteers with a piece of the pulse signal, showing promising potential in future human-machine interaction personalized with medical services, communications, and entertainment.

Nursing students' perceived anxiety and heart rate variability in mock skill competency assessment.

Skill competency assessments induce stress and anxiety and may affect nursing student performance. Little is known about stress and perceived anxiety levels and their relationship in the mock skill competency assessment. A cross-sectional study was conducted to examine the stress levels (as assessed by heart rate variability, HRV) and perceived anxiety before, during and after the mock skill competency assessment, and to explore their relationships to performance in a total of ninety first-year undergraduate nursing students. The HRV decreased significantly during the assessment and increased significantly 10 min after the assessment (p < 0.01). Higher performers showed significantly lower HRV during and after the assessment (p < 0.01). The assessment score was negatively correlated with HRV during and after the assessment (p < 0.05). Considering assessment-related stress and anxiety through a mock assessment prior to the actual skill assessment provides implications for future nursing education.

O040 Assessment of Heart Rate Variability During Respiratory Events and Arousals Using Symbolic Dynamics

Abstract Introduction Beat-to-beat heart rate dynamics vary during obstructive respiratory events and in both respiratory and spontaneous arousals. However, conventional quantifications of heart rate variability (HRV) require segments of data substantially longer than the typical respiratory event or arousal. Subsequently, previous studies investigating dynamics in these significantly shorter segments have utilised simple quantifications such as peak heart rate. This study aimed to more-richly characterise HRV during obstructive respiratory events and arousals using symbolic dynamics. Methods One hundred individuals with suspected obstructive sleep apnoea (55 male, 57.1±12.9 years) were studied with diagnostic polysomnography, including electrocardiography. R-wave intervals were calculated and extracted during respiratory events terminating with/without arousals and during spontaneous and respiratory arousals. The symbolic dynamics tool “heart rate fragmentation” was applied to quantify HRV during the events, whereby the percentage of inflection points (PIP), defined as beat-to-beat transitions from heart-rate acceleration to heart-rate deceleration, were calculated. Statistical analysis was conducted with the Wilcoxon rank sum test. Results PIP was higher during respiratory events terminated with arousal compared with those without arousal (52.9±6.4% vs. 48.5±6.7%, P&amp;lt;0.05). PIP was also higher during spontaneous arousals than during respiratory arousals (51.3±6.1% vs. 45.8±6.7%, P&amp;lt;0.05). Discussion Previous mechanistic experiments have associated increased PIP with greater parasympathetic activity. Thus, our preliminary results suggest greater parasympathetic activity during respiratory events terminated by arousal than those without; and during spontaneous arousals compared with respiratory arousals. Further work is required to understand the pathophysiology underlying this and other similar metrics, potentially leading to novel obstructive sleep apnoea-related cardiorespiratory pathology biomarkers.

Heart Rate Variability Assessment of Land Navigation and Load Carriage Activities in Specialist Police Selection.

Police tactical group (PTG) personnel are exposed to physical, mental, and emotional stressors. Consequently, PTG selection courses (SCs) impart similar challenges, often resulting in candidate attrition. Holistic assessment may provide additional support to stakeholders given these risks. Heart Rate Variability (HRV) is an objective holistic stress measure that may be applicable in PTG SCs but has not been thoroughly researched. Therefore, this study aimed to report HRV data in an end-user accessible format and determine the relationship between HRV and attrition. A total of 18 qualified Australian State law enforcement officers completed a 1-day physical readiness assessment. Of those, six males progressed to an additional two-day course, on which this study is focused. This two-day selection consisted of additional physical challenges and occupational assessments. HRV was obtained from 2-lead ECGs and defined as the percentage of R-R intervals that varied by ≥50 ms (pRR50). Data were summarized in a heat map of consecutive short-term analyses. Three candidates withdrew. A logistic regression based on heat map data found high HRV was significant for predicting attrition, χ2 (6) = 8.318, p = 0.004. HRV may provide insight for PTG stakeholders monitoring attrition. While the sample size was limited and replication is needed, this study tentatively establishes value for HRV monitoring in PTG SCs.

Autonomic dysfunction in systemic sclerosis: A scoping review

IntroductionOver the years several lines of evidence have implied a pathological involvement of autonomic nervous system (ANS) in systemic sclerosis (SSc). However, the relationship between autonomic dysfunction and SSc is not yet fully understood. The aims of this scoping review were to map the research done in this field and inform future research to investigate pathogenic hypotheses of ANS involvement. MethodsWe performed a scoping review of publications collected through a literature search of MEDLINE and Web of Science databases, looking for dysautonomia in SSc. We included original data from papers that addressed ANS involvement in SSc regarding pathogenesis, clinical presentation and diagnostic tools. Results467 papers were identified, 109 studies were selected to be included in the present review, reporting data from a total of 2742 SSc patients. Cardiovascular system was the most extensively investigated, assessing heart rate variability with 24 h HolterECG or Ewing's autonomic tests. Important signs of dysautonomia were also found in digital vasculopathy, gastrointestinal system and SSc skin, assessed both with non-invasive techniques and histologically. Research hypotheses mainly regarding the relationship between sympathetic system – ischemia and the role of neurotrophins were then developed and discussed. ConclusionWe described the currently available evidence on pathogenesis, clinical presentation and diagnostic assessment of dysautonomia in SSc patients. A strong influence of ANS deregulation on SSc clearly emerges from the literature. Future research is warranted to clarify the mechanisms and timing of autonomic dysfunction in SSc.

Autonomic dysregulation in long-term patients suffering from Post-COVID-19 Syndrome assessed by heart rate variability

Post-COVID-19 Syndrome (PCS) is a condition with multiple symptoms partly related to dysregulation of the autonomic nerve system. Assessment of heart rate variability (HRV) using 24 h Holter-ECG may serve as a surrogate to characterize cardiac autonomic activity. A prospective study including 103 PCS patients (time after infection = 252 days, age = 49.0 ± 11.3 years, 45.7% women) was performed and patients underwent detailed clinical screening, cardiopulmonary exercise testing, and 24 h Holter monitoring. Data of PCS patients was compared to 103 CAD patients and a healthy control group (n = 90). After correction for age and sex, frequency-related variables differed in PCS patients compared to controls including LF/HFpower, LF/HFnu, and LF/HF ratio (24 h; p ≤ 0.001). By contrast, these variables were largely comparable between PCS and CAD patients, while sympathetic activation was highest in PCS patients during the 24 h period. Overall, PCS patients showed disturbed diurnal adjustment of HRV, with impaired parasympathetic activity at night. Patients hospitalized during acute infection showed an even more pronounced overactivation of sympathetic activity compared to patients who underwent ambulant care. Our data demonstrate persistent HRV alterations in PCS patients with long-term symptom duration, suggesting a sustained impairment of sympathovagal balance. Moreover, sympathetic overstimulation and diminished parasympathetic response in long-term PCS patients are comparable to findings in CAD patients. Whether HRV variables have a prognostic value in PCS and/or might serve as biomarkers indicating a successful interventional approach warrants further longitudinal studies.

Stress and the cardiovascular system performance: current state of the problem (literature overview)

Annotation. Today, the adaptation of people during the warin Ukraine is an important medical and social problem, and for many it serves as an extreme factor affecting changes in the dynamics of physiological processes. Stress is a universal adaptive reaction that causes changes in the functioning of all body systems. One of the adverse consequences of chronic psychological stress is the development of cardiovascular diseases. The purpose of the work is to systematize and analyze the existing problematic aspects of the influence of stress on the activity of the cardiovascular system and to separate the most substantiated approaches to assessing the effects of stress. From the GoogleScholar, PubMed data bases, 45 recent publications on this issue were selected and reviewed. The analysis of literary sources determines the growing interest in the problem of reactivity of the cardiovascular system to psycho-emotional stress. The impact of stress on the human body can be both positive and negative. When stress is short-lived and very strong, it has a beneficial effect, and, on the contrary, if it is intense, acute and long-lasting, it has an adverse effect. One of the tools for objective assessment of stress is heart rate variability, which is recognized as an indicator of autonomic nervous activity. The work examines the invariance of heart rate variability indicators as indicators of the body's stress resistance in the modern distressed anthropogenic environment. Thus, the determination of changes in the regulation of the activity of the cardiovascular system caused by stress at the initial stages has an important prognostic value regarding the development and prevention of possible cardiovascular complications. Observation of stress-related changes in heart rate variability can be used to objectively assess stress. It is worth emphasizing the predictive value of the heart rate variability assessment method, rather than its physiological interpretation.

An Obstructive Sleep Apnea - A Novel Public Health Threat.

In patients with obstructive sleep apnea (OSA) during obstructive events, episodes of hypoxia and hypercapnia may modulate the autonomic nervous system (ANS) by increasing sympathetic tone and irritability, which contributes to sympathovagal imbalance and ultimately dysautonomia. Because OSA can alter ANS function through biochemical changes, we can assume that heart rate variability (HRV) will be altered in patients with OSA. Most studies show that in both the time and frequency domains, patients with OSA have higher sympathetic components and lower parasympathetic dominance than healthy controls. These results confirm autonomic dysfunction in these patients, but also provide new therapeutic directions. Respiratory methods that modulate ANS, e.g., cardiorespiratory biofeedback, could be beneficial for these patients. Heart rate variability assessment can be used as a tool to evaluate the effectiveness of OSA treatment due to its association with autonomic impairment.

Detection of Early Cardiac Affection in Post-COVID Syndrome Using Heart Rate Variability and 2D Global Longitudinal Strain Echocardiographic Assessment of the Left Ventricle

Abstract Aim and objectives The aim of our study is to estimate the Heart Rate Variability (HRV) &amp; two-dimensional global longitudinal strain (GLS) by speckle tracking echocardiography (2D STE) in post-COVID-19 patients after mild to moderate acute SARS COV-2 infection. Patients and Methods This study included fifty consecutive subjects between 17 &amp; 82 years of age who were symptomatic after three weeks up to 3 months of experiencing mild to moderate COVID19 illness according to the CDC criteria of severity. Patients enrolled were coming for follow-up clinic visits at Ain Shams University Hospitals between June 2021- Jan2022. All patients had normal LVEF upon enrollment as assessed by M-mode and Modified Simpson's method. 2D Left Ventricular Global Longitudinal Strain (GLS) and 24-hours Holter monitoring were performed for all patients. Results The LVGLS and HRV were significantly impaired in the symptomatic post-COVID-19. LVGLS was below -16 in 20% of the patients while 22% were in the grey zone; between -18 and -16. SDNN was decreased (&amp;lt; 100 msec) in 24% of the patients. RMSSD values favored a mean below 40 msec with prevalence of 58% among the study population. LF/HF ratio was above 2 in 42% of the patients. Our research suggested a highly significant association between LVGLS and HRV; as 66.7% of patients with decreased SDNN had impaired LVGLS, as opposed to 33% who had normal LVGLS (p-value 0.000) Conclusion LVGLS measured by Speckle Tracking Echocardiography (STE) is an important bedside tool, alternative to CMR which is the gold standard, in assessing LV systolic functions post COVID-19. HRV can explain a lot of post- COVID symptoms attributed to dysautonomia. In our study, we targeted the patients having prolonged symptoms after COVID-19 illness, GLS and HRV were assessed trying to explain the cardiac involvement and if it is the cause of the so called" long COVID". We found high incidence of GLS impairment using STE as well as significant prevalence of diminished HRV. HRV (especially SDNN) and GLS were significantly correlated as 80% of the patients with impaired GLS had decreased SDNN (p-value 0.00).

SP11.10 Assessment of Heart Rate Variability as A Marker of Stress and Cognitive Load During Vascular Surgery: Surgical Training

Abstract Introduction Decreased heart rate variability (HRV) correlates with subjective stress (STAI-6 score) and demonstrates increased stress at challenging steps during vascular surgery. This observational study aimed to examine HRV utility as an objective measure of stress and satisfaction during intra-operative vascular surgical training; hypothesising detrimental HRV change is associated with: (1) low training satisfaction, (2) operating compared to assisting, and (3) lower surgical experience. Methods Change from baseline (%) in HRV (SDNN - overall variability and LFHF - sympathetic tone) was calculated during arterial cutdown and arterial closure training points in 7 trainers and 10 trainees during 9 femoral vascular procedures. Pearson’s correlation coefficient was used to investigate association between training satisfaction and operative HRV in trainees, and overall operative experience and training point HRV. Mann-Whitney-U was used to investigate HRV difference in operating trainees with high versus average training satisfaction and operating versus assisting/supervising training points. Results Data (median (IQR)) included 13 cutdowns and 12 closures. Training satisfaction did not relate to STAI-6 or HRV. LFHF was significantly lower in trainers when operating (n=2) compared to supervising (n=10) cutdown (-18.96(-27.87--10.05) vs 36.96(10.83-147.2) p=0.0409*). No difference was seen during closure or in trainees. Operative LFHF non-significantly decreased with experience overall (r=-0.342, p=0.0944) and during cutdown (r=-0.498, p=0.0833), no association existed for assisting. Conclusion HRV may objectively measure stress during in-theatre training. This study suggests trainers may experience more stress when supervising rather than operating. Larger studies are required to demonstrate a more definitive relationship between training, stress and HRV.

Exploring Biomarkers of Mental Flexibility in Healthy Aging: A Computational Psychometric Study.

Mental flexibility (MF) has long been defined as cognitive flexibility. Specifically, it has been mainly studied within the executive functions domain. However, there has recently been increased attention towards its affective and physiological aspects. As a result, MF has been described as an ecological and cross-subject skill consisting of responding variably and flexibly to environmental cognitive-affective demands. Cross-sectional studies have mainly focused on samples composed of healthy individual and of patients with chronic conditions such as Mild Cognitive Impairment and Parkinson's, emphasizing their behavioral rigidity. Our study is the first to consider a sample of healthy older subjects and to outline physiological and psychological markers typical of mental flexibility, to identify functional biomarkers associated with successful aging. Our results reveal that biomarkers (respiratory and heart rate variability assessments) distinguished between individuals high vs. low in mental flexibility more reliably than traditional neuropsychological tests. This unveiled the multifaceted nature of mental flexibility composed of both cognitive and affective aspects, which emerged only if non-linear multi-variate analytic approaches, such as Supervised Machine Learning, were used.

The Cardiac Comeback-Beating Stronger: Exploring the Remarkable Resilience of the Heart in COVID-19 Recovery through Cardiac Autonomic Analysis.

Background and Objectives: Analyzing the cardiac autonomic function in COVID-19 patients can provide insights into the impact of the virus on the heart's regulatory mechanisms and its recovery. The autonomic nervous system plays a crucial role in regulating the heart's functions, such as heart rate, blood pressure, and cardiac output. This study aimed to investigate the impact of COVID-19 on heart rate variability (HRV) during a 6-min walk test (6MWT). Materials and Methods: The study included 74 participants, consisting of 37 individuals who had recovered from mild to moderate COVID-19 and 37 healthy controls. The study assessed heart rate variability (HRV) and blood pressure both before and after a 6-min walk test (6MWT). Results: The study found significant differences in a few time domains (SDNN and pNN50) and all frequency domain measures, whereas there were no significant differences in demographic characteristics or blood pressure between COVID-19-recovered individuals and healthy controls at rest. There were significant 6MWT effects on average HR, time-domain (SDNN and pNN50) measures of HRV, and all frequency domain measures of HRV. A significant group × 6MWT interaction was found for SDNN, pNN50, total power, Ln total power, LF, HF, Ln LF, Ln HF, and LF nu. Conclusions: Cardiac Autonomic analysis through HRV is essential to ensure the continued health and well-being of COVID-19 survivors and to minimize the potential long-term impacts of the disease on their cardiovascular system. This suggests that HRV analysis during the recovery phase following exercise could serve as a valuable tool for evaluating the physiological effects of COVID-19 and monitoring the recovery process.

Arterial Stiffness Associated with Sympathetic Hyperactivity in Obese Individuals with Moderate to Severe Obstructive Sleep Apnea.

Obstructive Sleep Apnea (OSA) is a chronic disorder associated with several risk factors, and increased Body Mass Index (BMI) and waist circumference are correlated with it is severity. Toevaluate vascular function, central hemodynamics, and autonomic modulation in obese individuals with moderate and severe OSA. Individuals of both sexes, aged 40-70 years and BMI ≥ 30 and < 40 kg/m2, were submitted to assessment of heart rate variability, endothelial function by flow-mediated dilatation, central parameters by oscillometry and carotid ultrasound. The sleep study was performed through a portable home sleep test device (WatchPAT). Patients (n = 76) were divided according to Apnea-Hypopnea Index (AHI): absent-mild group (AHI < 15 events/h, n = 30) and Moderate-Severe (MS) group (AHI ≥ 15 events/h, n = 46). The Low/High Frequency (LF/HF) ratio (0.81 ± 0.48 vs 1.39 ± 1.08 ms2, p = 0.035), Pulse Wave Velocity (PWV; 6.9 ± 0.7 vs 7.7 ± 1.6m/s, p = 0.004), vascular age (48 ± 6 vs 53 ± 9 years, p = 0.05) and mean intima-media thickness (0.59 ± 0.08 vs 0.66 ± 0.13 mm, p = 0.011) were significantly higher in the MS group. AHI was significantly correlated with PWV (r = 0.26, p = 0.024) and LF/HF ratio (r = 0.40, p < 0.001). Only in the MS group, PWV was significantly correlated with SD2/SD1 ratio (r = 0.611, p ≤ 0.001), and flow-mediated dilation with central systolic blood pressure (r = 0.364, p = 0.018), even after adjustment for age and sex. In this sample of obese individuals, moderate to severe OSA was associated with sympathetic hyperactivity and evidence of accelerated vascular aging with arterial stiffness and subclinical atherosclerosis.

The influence of insulin resistance variables on heart rate variability indices in mature men under Russia’s North conditions

BACKGROUND: Heart rate autonomic regulation can go out of balance which is normally assessed by the heart rate variability (HRV) indices. Similarly, it is relevant to research if and how HRV fluctuations can be influenced by varying signs of insulin resistance since they are quite common in Northern men. At present, there is no evidence of this influence in the North residents of older ages.AIM: This study aimed to comparatively assess heart rate variability in mature men who do or do not feature metabolic signs of insulin resistance.MATERIALS AND METHODS: Seventy-three mature aged male residents of Magadan Region, Caucasian by origin, were examined. All the subjects were divided into two groups: Group without insulin resistance signs (HOMA-IR index &lt; 2.5 units) and Group with insulin resistance signs (HOMA-IR index &gt; 2.5 units). We used immunochemiluminescent and enzymatic methods, and heart rate variability was assessed using the Varikard (Russia).RESULTS: Our research showed that 48% of all the examinees exhibited signs of insulin resistance along with an increase in the sympathetic activity in heart rate regulation. We also identified the heart rate indicators that had proved to undergo the most significant changes depending on the HOMA-IR index and the presence or absence of signs of insulin resistance: MxDMn, pNN50, SDNN, AMo50, SI, TP, HF, LF, and Body Mass.CONCLUSION: In general, the results obtained allow for ascertaining the high proportion of male Northerners of mature age with signs of insulin resistance. We also claim that those examinees demonstrate an autonomic imbalance and a moderate dominance of the sympathetic activity with a simultaneous decrease in activation of the parasympathetic link of autonomic nervous system and high body mass variables. At the same time, the correlations and causal associations among signs of insulin resistance, activation of the sympathetic link of autonomic nervous system, and overweight remain unclear. Apparently, all the analyzed features are likely to complement each other rather than completely exclude each other. The triad of obesity, signs of insulin resistance, and activation of the sympathetic link of autonomic nervous system is a driving factor for significant health risks. This study is expected to spread the use of the method of assessing heart rate variability based on insulin resistance signs as well as in reliance on metabolic disorders in general in a sample of mature men.

Validation of Photoplethysmography Using a Mobile Phone Application for the Assessment of Heart Rate Variability in the Context of Heart Rate Variability-Biofeedback.

Heart rate variability-biofeedback (HRV-BF) is an effective intervention to reduce stress and anxiety and requires accurate measures of real-time HRV. HRV can be measured through photoplethysmography (PPG) using the camera of a mobile phone. No studies have directly compared HRV-BF supported through PPG against classical electrocardiogram (ECG). The current study aimed to validate PPG HRV measurements during HRV-BF against ECG. Fifty-seven healthy participants (70% women) with a mean (standard deviation) age of 26.70 (9.86) years received HRV-BF in the laboratory. Participants filled out questionnaires and performed five times a 5-minute diaphragmatic breathing exercise at different paces (range, ~6.5 to ~4.5 breaths/min). Four HRV indices obtained through PPG, using the Happitech software development kit, and ECG, using the validated NeXus apparatus, were calculated and compared: RMSSD, pNN50, LFpower, and HFpower. Resonance frequency (i.e., optimal breathing pace) was also compared between methods. All intraclass correlation coefficient values of the five different breathing paces were "near perfect" (>0.90) for all HRV indices: lnRMSSD, lnpNN50, lnLFpower, and lnHFpower. All Bland-Altman analyses (with just three incidental exceptions) showed good interchangeability of PPG- and ECG-derived HRV indices. No systematic evidence for proportional bias was found for any of the HRV indices. In addition, correspondence in resonance frequency detection was good with 76.6% agreement between PPG and ECG. PPG is a potentially reliable and valid method for the assessment of HRV. PPG is a promising replacement of ECG assessment to measure resonance frequency during HRV-BF.

Short- vs long-term assessment of heart rate variability: Clinical significance in Dravet Syndrome

PurposeHeart rate variability (HRV) is a promising prognostic biomarker in Dravet Syndrome (DS), but different studies are not always comparable, limiting its clinical application. In fact, multiple HRV parameters, analyzed over different timescales and in different states are reported. The aim of this study was to assess which HRV parameter is more reproducible and clinically significant, analyzing differences between wake and sleep. MethodPatients with DS, with available 24 h-ECG Holter-derived HRV, were screened to evaluate if they had EEG-derived ECG traces available within one month before/after the Holter. A 5-minute period in the awake and sleep state were analyzed and correlated with the 24 h-HRV. Several relevant clinical features such as age, a recent history of status epilepticus (SE), and frequent generalized tonic-clonic seizures (GTCS) were correlated to HRV parameters with multiple linear regression models. ResultsThirty-oneawake recordings and 22 sleep recordings were included. HF was the parameter with the highest correlation in awake (Rho 0.745, p < 0.001) and in sleep (Rho 0.727, p < 0.001). Age was a significant factor in simple models for most of the parameters except RMSSD. A recent history of SE was associated with a significant reduction of HRV, both in simple and multiple regressions for all parameters except for awake LF and for sleep RMSSD and PNN50. Frequent GTCS were associated with a significant decrease in sleep RMSSD, HF, and LF, also when correcting for the effect of age and history of SE. When compared pairwise, a significant increase in sleep was seen for HF (median + 24.45 ms2, IQR −7.51/+172.18 ms2, p = 0.036; increase in 15/22 patients). ConclusionA moderate degree of correlation between long- and short-term HRV was seen both in sleep and in awake, and a strong correlation for awake HF. HF, both in awake and sleep, was significantly associated with high seizure burden, including SE and frequent GTCS.