Heat Rate Variability Research Articles

Neuroinflammation in the medullary visceral zone exert a powerful impaction on the systemic inflammation in sepsis through cholinergic anti-inflammatory pathway

To investigate whether sepsis-induced neuroinflammation of medulla visceral zone (MVZ) predominates the systemic inflammation through cholinergic anti-inflammatory pathway (CAP), and to explore the effect of central anti-inflammation on systemic inflammation. 112 adult Sprague–Dawley male rats were randomly divided into sepsis experimental group (n = 56) and neuroinflammation experimental group (n = 56). The two experimental groups were individually randomly divided into control group (n = 8), model group (n = 16), central anti-inflammatory group (n = 16) and vagus transection group (n = 16). Rats in two control groups were administered with saline at the dose of 6 mL/kg intraperitoneally or with 25 μL artificial cerebrospinal fluid injected into forth ventricle once a day for 3 days. Rats in two model groups were administered with Lipopolysaccharide (LPS) at the dose of 6 mg/kg intraperitoneally or with 25 μg/25 μL LPS injected into forth ventricle once a day for 3 days. Rats in two central anti-inflammatory groups were fed with 10 mg/mL minocycline sucrose solution as the only water source for 4 days prior to be treated as the model groups of their own, and feeding style was continued until the end of the experiment. Rats in the two vagus transection groups were undergone right vagotomy and 7 days of adaptive feeding prior to be treated as the same as those in the central anti-inflammatory group of their own. The Murine Sepsis Score (MSS), mortality rate and heat rate variability (HRV) were recorded during the last 3 days of intervention. Then the rats were sacrificed and blood samples were collected for ELISA analysis to detect the serum level of inflammatory cytokines such as TNF-α, IL-6, and IL-10. The expression of TNF-α and IL-6 in medulla oblongata were analyzed by Western blot. The correlation and regression analysis among the expression levels of cytokines in medulla oblongata, HRV indexes and serum inflammatory cytokines were performed. The mortality rate and MSS of the sepsis model group and the MVZ’s neuroinflammation model group were significantly higher than those of their own control group, and the central anti-inflammation reduced the mortality rate and MSS scores of the two model groups, while the right vagotomy abolished the effect of central anti-inflammatory. In the sepsis model group and the MVZ’s neuroinflammation model group, the levels of TNF-α, IL-6, and other cytokines in serum and MVZ were significantly increased, and HRV indexes (SDNN, RMSSD, LF, HF, LF/HF) were significantly decreased (P = 0.000). Central anti-inflammatory treatment reversed the above changes. However, right vagotomy abolished the central anti-inflammatory effect. Correlation and regression analysis showed that there was a significant linear correlation among the expression of inflammatory factors in MVZ, the indexes of HRV and the levels of serum cytokines. Our study shows that sepsis-induced MVZ’s neuroinflammation exert a powerful influence on the systemic inflammation through CAP in sepsis. Central anti-inflammation effectively improves systemic inflammation through inhibiting MVZ’s neuroinflammation in sepsis. The time domain and frequency domain indexes of HRV can reflect the regulatory effect of CAP and the degree of inflammation of MVZ, which may be potentially used to monitor the condition and treatment effectiveness of sepsis patients.

Onboard guidance and control algorithms for increased autonomous aerobraking capabilities at Mars

Aerobraking represents a valuable option for interplanetary missions thanks to its capability of reducing the orbital semi-major axis through multiple atmospheric passages, thus with limited fuel consumption. However, due to structural and thermal loads the spacecraft undergoes, mission risks and ground operations costs increase. This study aims to tackle this aerobraking drawback by enhancing its autonomy. The main activities required for aerobraking execution, including atmospheric prediction, orbital state estimation, and orbit control, are tailored for onboard execution. Regarding orbit control, two different methodologies, differentiated by working principle and prediction horizon breadth, are investigated. The first plans orbit control manoeuvres based on the prediction of the atmospheric conditions for a single upcoming pericentre, while the second schedules and optimizes the manoeuvres considering the recent atmospheric conditions experienced by the spacecraft and the altitude trend of multiple upcoming pericentres. The whole operational concept is tested within a simulated environment, with the primary objective of accurately reproducing the intense atmospheric variations of the Martian atmosphere, which represents the most challenging aspect during aerobraking execution. The numerical testing, involving the simulation of different aerobraking regimes under varied conditions, shows that the natural dynamics of the orbital motion can be exploited to minimize both fuel consumption for orbit control manoeuvres and spacecraft load variations, thus enabling more efficient aerobraking and more stable flight conditions, even with the limited predictive capabilities that characterize onboard resources. Both control logics permit the aerobraking execution without exceeding the maximum allowed thermal limits, hence showing their effectiveness. Furthermore, a Monte Carlo analysis conducted on a complete aerobraking simulation reveals a 25.5% reduction in propellant consumption and a 9.4% reduction in heat rate variability when the orbit control decision process uses information relative to multiple future pericentres.

Stretchable Photodiodes with Polymer-Engineered Semiconductor Nanowires for Wearable Photoplethysmography.

Healthcare systems worldwide have been stressed to provide sufficient resources to serve the increasing and aging population in our society. The situation became more challenging at the time of pandemic. Technology advancement, especially the adoption of wearable health monitoring devices, has provided an important supplement to current clinical equipment. Most health monitoring devices are rigid, however, human tissues are soft. Such a difference has prohibited intimate contact between the two and jeopardized wearing comfortableness, which hurdles measurement accuracy especially during longtime usage. Here, we report a soft and stretchable photodiode that can conformally adhere onto the human body without any pressure and measure cardiovascular variables for an extended period with higher reliability than commercial devices. The photodiode used a composite light absorber consisting of an organic bulk heterojunction embedded into an elastic polymer matrix. It is discovered that the elastic polymer matrix not only improves the morphology of the bulk heterojunction for obtaining the desired mechanical properties but also alters its electronic band structure and improves the electrical properties that lead to a reduced dark current and enhanced photovoltage in the stretchable photodiode. The work has demonstrated high fidelity measurements and longtime monitoring of heat rate variability and oxygen saturation, potentially enabling next-generation wearable photoplethysmography devices for point-of-care diagnosis of cardiovascular diseases in a more accessible and affordable way.

HEART RATE VARIABILITY AS AN OBJECTIVE CRITERION FOR THE PSYCHO-EMOTIONAL STATE OF COMBATANTS.

The aim: To evaluate the functioning of the autonomic nervous system in combatants, the relationship between the heat rate variability (HRV) and ques¬tionnaire indicators, to improve the diagnosis of post-traumatic stress disorder (PTSD) and to evaluate the effectiveness of Transcendental Meditation (TM). Materials and methods: 57 combatants and 30 civilians, with registering ECG and HRV-analysis, self-questionnaire testing. Results: The combatants' group showed an increase in heart rate, in the degree of centralisation of heart rate control and the R. Bayevsky stress index, a decrease in the total HRV value. PTSD score was negatively correlated with pNN50. The indicator «Stress» (by DASS-21), revealed negative relationships with the TP, (LF+HF), RMSSD, HF, HFn. The effects of TM on HRV are to save the work of the cardiovascular system (reduced heart rate), reduce the level of nervous and emotional stress, increase the overall adaptation reserve. After TM, the HRV spectrum retains the same proportions of very low, low, and high frequencies as in the baseline state. Conclusions: The study objectively proved the presence of neuro-emotional stress and depletion of autonomic regulation reserves in combatants, both by questionnaire surveys and HRV analysis. The high level of correlation between HRV and questionnaire indicators gives grounds for the introduction of HRV analysis for the initial assessment of the psycho-emotional state and tracking its dynamics, as well as for assessing the effectiveness of its correction. Our use of TM has confirmed its effectiveness in correcting the psycho-emotional state.

Heat Rate Variability

Heat Rate Variability

The development of a novel high-precision major depressive disorder screening system using transient autonomic responses induced by dual mental tasks

12.6% of major depressive disorder (MDD) patients have suicide intent, while it has been reported that 43% of patients did not consult their doctors for MDD, automated MDD screening is eagerly anticipated. Recently, in order to achieve automated screening of MDD, biomarkers such as multiplex DNA methylation profiles or physiological method using near infra-red spectroscopy (NIRS) have been studied, however, they require inspection using 96-well DNA ELIZA kit after blood sampling or significant cost. Using a single-lead electrocardiography (ECG), we developed a high-precision MDD screening system using transient autonomic responses induced by dual mental tasks. We developed a novel high precision MDD screening system which is composed of a single-lead ECG monitor, analogue to digital (AD) converter and a personal computer with measurement and analysis program written by LabView programming language. The system discriminates MDD patients from normal subjects using heat rate variability (HRV)-derived transient autonomic responses induced by dual mental tasks, i.e. verbal fluency task and random number generation task, via linear discriminant analysis (LDA) adopting HRV-related predictor variables (hear rate (HR), high frequency (HF), low frequency (LF)/HF). The proposed system was tested for 12 MDD patients (32 ± 15 years) under antidepressant treatment from Shizuoka Saiseikai General Hospital outpatient unit and 30 normal volunteers (37 ± 17 years) from Tokyo Metropolitan University. The proposed system achieved 100% sensitivity and 100% specificity in classifying 42 examinees into 12 MDD patients and 30 normal subjects. The proposed system appears promising for future HRV-based high-precision and low-cost screening of MDDs using only single-lead ECG.

Cardiac autonomic nerve function in obese school-age children

To analyze the deceleration capacity (DC) of heart rate, acceleration capacity (AC) of heart rate, and heat rate variability (HRV) in obese school-age children, and to observe the correlations of BMI with DC, AC, and HRV in these children. A total of 108 obese school-age children were selected, including 75 cases of ortholiposis and 33 cases of dyslipidemia. A total of 103 healthy school-age children were selected as control group. All the subjects underwent 24-hour ambulatory electrocardiography. The comparisons of DC, AC, and HRV were made between the obese and control groups, as well as between children with ortholiposis and dyslipidemia in the obese group. The correlations of BMI with DC, AC, and HRV were analyzed in the obese group. The obese group showed lower DC, standard deviation of normal-to-normal R-R intervals (SDNN), standard deviation of the average normal-to-normal intervals (SDANN), root mean square of successive differences (RMSSD), low-frequency power (LF), and high-frequency power (HF) than the control group. The AC of the obese group was significantly higher than that of the control group (P<0.05). In the obese group, children with dyslipidemia had significantly lower DC, SDNN, SDANN, RMSSD, LF, and HF, but significantly higher AC and BMI, as compared with those with ortholiposis (P<0.01). In the obese group, BMI was negatively correlated with DC, SDNN, SDANN, RMSSD, and HF (P<0.05), but positively correlated with AC (P<0.05). Obese school-age children have impaired autonomic nerve function, presenting with reduced vagal tone, which is particularly prominent in those with dyslipidemia. The more obese the children, the lower the vagal tone, which may increase the risks of cardiovascular diseases.

Observing continuous change in heart rate variability and photoplethysmography-derived parameters during the process of pain production/relief with thermal stimuli.

Continuously monitoring and efficiently managing pain has become an important issue. However, no study has investigated a change in physiological parameters during the process of pain production/relief. This study modeled the process of pain production/relief using ramped thermal stimulation (no pain: 37°C water, process of pain production: a heating rate of 1°C/min, and subject feels pain: water kept at the painful temperature for each subject, with each segment lasting 10 min). In this duration, the variation of the heat rate variability and photoplethysmography-derived parameters was observed. A total of 40 healthy individuals participated: 30 in the trial group (14 males and 16 females with a mean age of 22.5±1.9 years) and 10 in the control group (7 males and 3 females with a mean age of 22.5±1.3 years). The results showed that the numeric rating scale value was 5.03±1.99 when the subjects felt pain, with a temperature of 43.54±1.70°C. Heart rate, R-R interval, low frequency, high frequency, photoplethysmography amplitude, baseline, and autonomic nervous system state showed significant changes during the pain production process, but these changes differed during the period Segment D (painful temperature 10: min). In summary, the study observed that physiological parameters changed qualitatively during the process of pain production and relief and found that the high frequency, low frequency, and photoplethysmography parameters seemed to have different responses in four situations (no pain, pain production, pain experienced, and pain relief). The trends of these variations may be used as references in the clinical setting for continuously observing pain intensity.

Performance of dual-source CT with high pitch spiral mode for coronary stent patency compared with invasive coronary angiography.

ObjectiveTo investigate the performance of dual-source computed tomography (DSCT) using high-pitch spiral (HPS) mode for coronary stents patency.MethodsWe conducted a prospective study on 120 patients with 260 previous stents implanted due to recurred suspicious symptoms of angina scheduled for invasive coronary angiography (ICA), while DSCT were conducted using HPS mode.ResultsThere was no significant impact of age, body mass index or heat rate (HR) on image quality (P > 0.05), while HR variability had a slight impact on that (P < 0.05). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of DSCT in detection of in-stent restenosis (ISR) based per-patient were 92.3%, 96.7%, 88.9%, and 97.8%, respectively. And those based per-stent were 87%, 96.8%, 83.3%, and 97.7% with un-assessment stents, 97.4%, 99.5%, 97.4%, and 99.5% without un-assessment stents. There was significant difference on sensitivity, specificity, PPV and NPV between diameter ≥ 3.0 mm group (93.3%, 97.9%, 87.5%, and 98.9%) and diameter < 3.0 mm group (80%, 93.3%, 80.0%, and 93.3%) (P < 0.05), and that between stent number ≥ 3 group (82.3%, 77.8%, 66.7%, and 60%) with < 3 group (97.3%, 80%, 96.5%, and 75%). The effective dose of DSCT (1.4 ± 0.5 mSv) is significantly less than that by invasive coronary angiography [4.0 ± 0.8 mSv (P < 0.01)].ConclusionDSCT using HPS mode provides good diagnostic performance on stent patency with lower effective dose in patients with HR < 65 beats/min.

Modeling volatility in heat rate variability.

Modeling Heart Rate Variability (HRV) data has become important for clinical applications and as a research tool. These data exhibit long memory and time-varying conditional variance (volatility). In HRV, volatility is traditionally estimated by recursive least squares combined with short memory AutoRegressive (AR) models. This work considers a parametric approach based on long memory Fractionally Integrated AutoRegressive Moving Average (ARFIMA) models with heteroscedastic errors. To model the heteroscedasticity nonlinear Generalized Autoregressive Conditionally Heteroscedastic (GARCH) and Exponential Generalized Autoregressive Conditionally Heteroscedastic (EGARCH) models are considered. The latter are necessary to model empirical characteristics of conditional volatility such as clustering and asymmetry in the response, usually called leverage in time series literature. The ARFIMA-EGARCH models are used to capture and remove long memory and characterize conditional volatility in 24 hour HRV recordings from the Noltisalis database.

ВЛИЯНИЕ ФИЗИОЛОГИЧЕСКИХ ПАРАМЕТРОВ СПОРТСМЕНА-ПАРАШЮТИСТА В ДИСЦИПЛИНЕ КУПОЛЬНАЯ АКРОБАТИКА ЧЕТВЕРКИ РОТАЦИЯ НА РЕЗУЛЬТАТ

Настоящее исследование было проведено с целью оценки и выявления функционального состояния вегетативной и центральной нервной системы обеспечивающих достижение наилучшего спортивного результата у профессиональных спортсменов-парашютистов в период проведения чемпионата России в дисциплине купольная акробатика четверки ротация.Обследована национальная сборная России (всего 8 парашютистов), каждый спортсмен совершил от 5 до 7 перестроений. Изучение особенностей вегетативной регуляции у спортсменов проводили в покое и при выполнении активной ортостатической пробы с использованием спектрального анализа вариабельности ритма сердца. Показатели состояния центральной нервной системы оценивали с помощью психофизиологических методик.Установлено, что спортсмены, добивающиеся лучшего времени перестроения, характеризуются тремя основными параметрами: наименьшей степенью напряжения регуляторных систем по Р.М. Баевскому (в пределах между 2-й и 4-й степенью), наиболее выраженным симпатическим вазомоторным влиянием на ритм при фоновой записи РКГ и наивысшим уровнем функциональных возможностей ЦНС.

ВЛИЯНИЕ ФИЗИОЛОГИЧЕСКИХ ПАРАМЕТРОВ СПОРТСМЕНА-ПАРАШЮТИСТА НА ТОЧНОСТЬ ПРИЗЕМЛЕНИЯ

Настоящее исследование было проведено с целью оценки и выявления функционального состояния вегетативной и центральной нервной системы обеспечивающих достижение наилучшей точности приземления спортсменов-парашютистов в соревновательный период.Обследовано 16 парашютистов, каждый из которых совершил от 5 до 6 попыток. Изучение особенностей вегетативной регуляции у спортсменов проводили в покое и при выполнении активной ортостатической пробы с использованием спектрального анализа вариабельности ритма сердца. Показатели состояния центральной нервной системы оценивали с помощью психофизиологических методик.Установлено, что наилучшей точности приземления добиваются спортсмены имеющие наименьшую медиану значения времени реакции при проведении методики ПЗМР и преобладающее симпатическое вазомоторное влияние в покое, поэтому данные параметры наиболее целесообразно оценивать в тренировочном процессе спортсменов-парашютистов.

GENDER FEATURES OF NEUROTISM AND VEGETATIVE REGULATION IN YOUNG PEOPLE OF RUSSIAN NORTH

Manifestations of emotional excitability, the vegetative status and regulation of the heart rhythm in inhabitants of the North of Russia, students (n = 1 370, 853 girls and 517 young men aged 17-22 years, the North Group) and inhabitants of the Polar region, students of Vorkuta (n = 138, 79 girls and 59 young men, the Polar Group) have been studied. There were determined: emotional excitability (ЕЕ) by means of the Russian prototype «Scale of Emotional Arousability» (Braithwaite, 1987), the heat rate variability on the basis of registration of 500 ECG cycles with use of the computerized complex «REO-32» (firm "Micar", Russia), direct and calculated parameters of the system haemodynamics. The EE analysis has shown that the girls were described by higher manifestations of general emotionality, expressiveness of anger, shyness, absence of emotions control and, in aggregate, emotional excitability in comparison with the young men. Bigger dependence of the EE level on prevalence of mechanisms of parasympathetic regulation for the girls, rather than for young men has been established. It has been shown, that the level of neurotism among the youth of the Far North was stipulated not only by the gender dependence, but also by the north-latitude dependence.

O exercício físico atenua o déficit autonômico cardíaco induzido pelo bloqueio da síntese do óxido nítrico

BACKGROUND: The nitric oxide (NO) synthesis blockade is characterized by an increase in the cardiac sympathetic activity and the physical training promotes the decrease in the sympathetic activity. OBJECTIVE: We investigated the effect of the NO synthesis blockade on the autonomic cardiovascular control in rats submitted to aerobic exercises during a 10-week period. METHODS: Male Wistar rats were divided in four groups: control rats, treated with chow food and water ad libitum for 10 weeks (CR); control rats, treated with NG-nitro-L-arginine methyl ester (L-NAME) during the last week (CRL); rats trained during 10 weeks on an electrical treadmill (TR); rats trained for 10 weeks and treated with L-NAME during the last week (TRL). The autonomic cardiovascular control was investigated in all groups with the use of a double blockade with methylatropine and propranolol and analysis of variability. RESULTS: The CRL and TRL groups presented hypertension. The CRL group presented tachycardia and predominance of the sympathetic tonus in heat rate (HR) measurement after the pharmacological autonomic blockade. The TR group presented bradycardia and lower intrinsic HR when compared to the others. The evaluation of the HR variability showed lower absolute and normalized values in the low frequency (LF) band in the CRL group. On the other hand, the TRL presented an increase in the LF band in absolute values. The analysis of variability of the systemic arterial pressure (SAP) showed that the CRL and TRL groups presented higher values in the LF band. CONCLUSION: The previous physical exercise prevented the deficit in the autonomic cardiac control induced by the treatment with L-NAME, but did not prevent the increase in the SAP variability.

BLOCK ENTROPY ANALYSIS OF HEART RATE VARIABILITY SIGNALS

In this paper we present a novel approach to the analysis of Heat Rate Variability (HRV) data, by coarse-graining analysis using the estimation of Block Entropies with the technique of lumping. HRV time series are generated from long recordings of Electrocardiograms (ECGs) and are then filtered in order to produce a coarse-grained symbolic dynamics. Block Entropy analysis is applied to these dynamics in order to examine its coarse-grained statistics. Our data set is comprised of two subsets, one of healthy subjects and another of Coronary Artery Disease (CAD) patients. It is found that Entropy analysis provides a quick and efficient tool for the differentiation of these series according to subject category. Healthy subjects provided more complex statistics compared to patients; specifically, the healthy data files provided higher values of block Entropies compared to patient ones. We also compare these results with the Correlation Dimension Estimation in order to establish coherency. We believe that this analysis may provide a useful statistical method towards the better understanding of the human cardiac system.

Acute and chronic stress influence blood pressure variability in mice

There is evidence that alterations in heart rate and blood pressure variability (BPV) are associated with cardiovascular disease. We used a mice model to investigate the effects of acute and chronic stress on blood pressure variability (BPV) and heat rate variability (HRV). Shaker stress was given acutely (5 min, 150 cycles/min) and chronically (3 days, 2 min stress, 150 cycles/min, 45 sessions/day) in male C57BLJ mice. Systolic arterial pressure (SAP) and pulse interval (PI) time series were submitted to autoregressive spectral analysis with variability measured in the low-frequency (LF, 0.1–1.0 Hz) and high-frequency (HF, 1–5 Hz) ranges. In the acute experiment, MAP was increased significantly in the first 10 min poststress period (99±2 vs. 113±2 mm Hg) and returned to control levels 30 min poststress. HR was significantly higher in the initial poststress period (537±12 vs. 615±20 bpm). These alterations were associated with a marked increase in BPV (21±4 vs. 55±11 mm Hg2) and in power of LF oscillations (18±3 vs. 42±7 mm Hg2). On the other hand, chronic stress exposure produced a reduction in BPV (16±4 vs. 6±1 mm Hg2) and LF oscillations (11±3 vs. 3±1 mm Hg2). HRV was not altered after either acute or chronic stress. Spontaneous baroreflex sensitivity (SBS), determined by cross-spectral analysis between PI and BP, was reduced significantly in acute stress (−50%), but unchanged in chronic stress. Our results show that acute stress produced changes in BPV that may be associated with increased sympathetic activity and a reduction in blood pressure buffering. Under chronic conditions, there is no alteration in baroreflex sensitivity while BPV is reduced. This is likely related to the combination of sympathetic activation in the face of vasculature alterations.

Acute and chronic stress influence blood pressure variability in mice

There is evidence that alterations in heart rate and blood pressure variability (BPV) are associated with cardiovascular disease. We used a mice model to investigate the effects of acute and chronic stress on blood pressure variability (BPV) and heat rate variability (HRV). Shaker stress was given acutely (5 min, 150 cycles/min) and chronically (3 days, 2 min stress, 150 cycles/min, 45 sessions/day) in male C57BLJ mice. Systolic arterial pressure (SAP) and pulse interval (PI) time series were submitted to autoregressive spectral analysis with variability measured in the low-frequency (LF, 0.1–1.0 Hz) and high-frequency (HF, 1–5 Hz) ranges. In the acute experiment, MAP was increased significantly in the first 10 min poststress period (99±2 vs. 113±2 mm Hg) and returned to control levels 30 min poststress. HR was significantly higher in the initial poststress period (537±12 vs. 615±20 bpm). These alterations were associated with a marked increase in BPV (21±4 vs. 55±11 mm Hg 2) and in power of LF oscillations (18±3 vs. 42±7 mm Hg 2). On the other hand, chronic stress exposure produced a reduction in BPV (16±4 vs. 6±1 mm Hg 2) and LF oscillations (11±3 vs. 3±1 mm Hg 2). HRV was not altered after either acute or chronic stress. Spontaneous baroreflex sensitivity (SBS), determined by cross-spectral analysis between PI and BP, was reduced significantly in acute stress (−50%), but unchanged in chronic stress. Our results show that acute stress produced changes in BPV that may be associated with increased sympathetic activity and a reduction in blood pressure buffering. Under chronic conditions, there is no alteration in baroreflex sensitivity while BPV is reduced. This is likely related to the combination of sympathetic activation in the face of vasculature alterations.