Heart Rate Variability Spectrum Research Articles

Inspiratory muscle training improves physical performance and cardiac autonomic modulation in older women.

Aging impairs the autonomic balance reducing the vagal and increasing the sympathetic components of heart rate variability (HRV) and this could be associated with a decline in physical capacity. Inspiratory muscle training (IMT) is a possible tool to attenuate this physical capacity decline in older women. The aim of this study was to investigate the influence of IMT in the older women on physical capacity and autonomic cardiac modulation at rest and post exercise. 20 female participants 60-72years old were randomly allocated in two groups. One group underwent IMT set at 50% of maximum inspiratory pressure (MIP), every day for 4weeks (IMT-group). The placebo group performed the same training procedure but with a minimal resistance (5% MIP; PLA-group). Every week, the IMT load was readjusted and the HRV evaluated at rest. The six-minute walk test (6MWT) was performed once pre and post IMT-intervention. The IMT-group and PLA-group performed the same test and intervention procedures. After a 5 weeks intervention, the MIP had significantly improved in the IMT-group but not in the PLA-group (p < 0.01; es = 1.17). The high frequency power of the HRV spectrum had already improved by the second week (p < 0.01; es = 1.13) and remained elevated until the last week of intervention (p < 0.01; es = 1.43). The same positive results were described in 6MWT distance (p = 0.04; es = 0.39) and the change (∆) of heart rate recovery (HRR) from 1min (p = 0.02; es = 0.68). IMT increases HRV, improves 6MWT distance and HRR.

Times Varying Spectral Coherence Investigation of Cardiovascular Signals Based on Energy Concentration in Healthy Young and Elderly Subjects by the Adaptive Continuous Morlet Wavelet Transform

ObjectiveThe aims of this study, to investigate the interaction among heart rate variability (HRV), respiratory, systolic arterial blood pressure variability (SABPV) and systolic arterial pressure interval variability (APIV) signals for understanding of cardiovascular control. MethodsIn this study, three methods referred as adaptive continuous Morlet wavelet transform (ADCMWT), adaptive Stockwell transform (ADST) and adaptive modified Stockwell transform (ADMST) was used to assess the accuracy (AC) of time-varying spectral coherence (TVSC). The adaptation of these estimators was based on maximum energy concentration measurement. The capability to correct temporal localization of time–frequency regions was validated on synthetic time series data modeled as dynamic characteristics of cardiovascular signals. ResultsThe results on synthetic simulated data show that the ADCMWT method allows for the temporal localization of the time–frequency regions with higher accuracy (AC > 96.074% for SNR ≥ 0 dB), compared to ADST (AC > 90.71% for SNR ≥ 0 dB) and ADMST (AC > 84.45% for SNR ≥ 5 dB). Further, the ADCMWT was applied to real cardiovascular data obtained from Fantasia standard data base and grouped as, 8 young subjects (4M + 4F, age range 23–32) and 8 elderly subjects (4M + 4F, age range 70–82) for estimating the TVSC in low frequency (LF) band (0.04 Hz–0.15 Hz) and high frequency (HF) band (0.15 Hz–0.4 Hz) of HRV spectrum. The global result depict that the median value of interquartile range of coherency between HRV-SABPV and HRV-APIV signals in LF and HF band were significantly (p=0.00001) lower in elderly group subjects compared to young group subjects. The coupling between HRV-Respiratory signals in LF band was not significantly affected with the aging of healthy subjects. However, this coupling in HF band significantly reduced in elderly compare to young group subjects (p=0.0125). ConclusionThe comparative study shows that the time-varying spectra and accurate localization of coupling between two physiological signals can be affected by energy concentration. The ADCMWT at w0=6, could be an alternative, possibly more suitable and highly accurate method for assessment and detection of time varying spectral and coherence components of cardiovascular time series.

INFLUENCE OF THE TOTAL POWER OF THE HEART RATE VARIABILITY SPECTRUM ON THE SPECTRAL PARAMETERS DISTRIBUTION IN PATIENTS WITH ARTERIAL HYPERTENSION IN A PACED BREATHING TEST

To determine the effect of the total power (TP) of the heart rate variability (HRV) spectrum on the distribution of high, low and very low frequency waves, 40 patients with arterial hypertension (AH) at the age of 58 ± 9 years were divided into 5 groups according to the degree of TP decrease in the initial stage of the test: 1st – more than 3000 ms2; 2nd – 3000–2000 ms2; 3rd – 2000-1000 ms2; 4th – 1000–500 ms2; 5th – less than 500 ms2. To assess HRV parameters in each group, 3 stages of the paced breathing test with a double (light and sound) metronome were evaluated; the hardware and software complex «Cardiolab» («HAI-Medica») was used. The distribution of the parameters was estimated taking into account the median, 25 and 75 quartiles. To estimate the differences between the statistical samples, the nonparametric Mann-Whitney U-test was used, as well as the Craskell–Wallis criterion. Statistically significant differences were considered between the data at a value of p &lt; 0.05. It was found that the greater is the degree of TP reduction, the more significant is the autonomic imbalance, as well as the decrease in the influence of paced breathing on the regulation of the heart rhythm; at TP values below 1000 ms2 not only the parasympathetic component decrease is observed, but also the transition from sympathicotonia to the neurohumoral factors prevalence. In patients with arterial hypertension, there is a tendency of decrease in the total power of the HRV spectrum, thus reflecting the decreased functional capacity of heart rhythm regulation.The lower the degree of TP, the more significant is the disturbance of HRV regulation with a decrease in the parasympathetic component of the heart rate variability spectrum and the dominant influence of sympathetic and neurohumoral factors.The influence of the paced breathing on the heart rhythm regulation falls depending on the decrease in the total power of the HRV spectrum: at TP values below 1000 ms2 not only the parasympathetic component decrease is observed, but also the transition from sympathotonia to the neurohumoral factors prevalence.Decrease in TP can be considered as an indicator of aggravation of autonomic and neurohumoral regulation.Thepaced breathing test allows determine the basic level of cardiac activity regulation and dynamic disruptions in the distribution of HRV components in the metronomized breathing, as well as the possibilities for restoring the regulatory balance of heart rate variability, which is especially important in the examination of patients with arterial hypertension.

Influence of additional risk factors on the antihypertensive efficacy of eprosartan and telmisartan in patients with essential hypertension

Objective. The aim of this study is to determine the effect of additional risk factors on blood pressure parameters, cardiovascular remodeling and the state of vegetative balance of the heart rhythm in patients with stage II essential hypertension (EH) under treatment with eprosartan and telmisartan.Materials and methods. The study included 100 patients with stage II essential hypertension (EH), 1–2 degrees with a low and moderate risk of developing cardiovascular complications. The smoker's status was 30.0 %, hypercholesterolemia more than 5 mmol/l – 69.0 %, overweight and obesity – 82.0 % of patients with EH. By randomisation, half of the patients received eprosartan in a daily dose of 600 mg, the rest received telmisartan at a daily dose of 80 mg for 6 months. Before the start of treatment and after 6 months of therapy, all the patients were subjected to the evaluation of general physical examinations, calculation of body mass index, determination of serum TC level, ECG Holter monitoring with analysis of heart rate variability, ambulatory blood pressure monitoring, echocardiography and duplex pulsed wave dopplerography of extracranial and intracranial vessels. Two weeks before the study, the patients did not take any antihypertensive drugs. Results. In patients with EH with additional risk factors using of eprosartan for 6 months is accompanied by a significant decrease in office SBP by 30.0 %, DBP by 21.6 %, PBP by 41.4 % and avg. BP by 25.5 %, regression of myocardial hypertrophy and improvement of diastolic function of the left ventricle. Eprosartan demonstrated a high antihypertensive efficacy on the effect on SBP in patients with EH with the presence/absence of tobacco smoking. However, the effect of eprosartan on DBP was better in patients with EH who do not have the status of a smoker. All the patients with EH, regardless of the presence or absence of an elevated level of total cholesterol, reached the target level of SBP under the influence of eprosartan. The antihypertensive effect of eprosartan against SBP was independent of the presence/absence of obesity in patients with EH. Eprosartan resulted in a significant increase in the maximum linear velocity in the left internal carotid artery by 2.8 % and in the vertebrobasilar region by 24.3 %. The total power of the spectrum under the influence of treatment significantly increased by 14.3 %.Antihypertensive therapy with telmisartan within half a year causes a significant decrease in office SBP by 24.8 %, DBP by 20.0 %, PBP by 31.8 %, avg. BP by 22.2 % In patients with EH who have/do not have the status of smoker and in all 100 % of patients with normal and elevated total cholesterol telmisartan was equally effective in achieving the target level of SBP. Obesity or its absence also did not significantly affect the effectiveness of antihypertensive therapy with telmisartan in patients with EH. Telmisartan, like eprosartan, causes regression of left ventricular hypertrophy. Telmisartan has a positive effect on carotid blood flow and does not affect the blood flow of the vertebrobasilar region. There were no changes in the parameters of the vegetative balance under the influence of telmisartan.Conclusion. In patients with EH with additional factors of cardiovascular risk using both eprosartan and telmisartan for half a year is accompanied by a significant decrease in blood pressure, regression of myocardial hypertrophy and improvement of diastolic function of the left ventricle, improvement of blood flow in the carotid region. In contrast to telmisartan, eprosartan increases the total power of the heart rate variability spectrum and does not affect the level of total cholesterol. The influence of telmisartan on the blood flow in the vertebrobasilar region is absent. Smoking, obesity, hypercholesterolemia do not reduce the antihypertensive efficacy of telmisartan and eprosartan against SBP and DBP. However, eprosartan is less effective in reducing DBP in patients with EH who smoke.

The absence of effect of ganglionated plexi ablation on heart rate variability parameters in patients after thoracoscopic ablation for atrial fibrillation.

Hybrid ablation [thoracoscopic ablation (TA) of atrial fibrillation (AF) followed by catheter ablation (CA)] is an increasingly common method of the treatment for patients with AF. The aim of this study was to assess the response to ganglionated plexi (GP) ablation in patients with a previous TA (i.e., to assess whether TA had resulted in damage to the GP. Heart rate variability (HRV) was used as a marker of the autonomic response. Twenty AF patients underwent pulmonary vein isolation (PVI) plus GP ablation (GP group) and 18 AF patients underwent CA including GP ablation as a part of hybrid ablation (i.e., all patients had undergone a previous TA; Hybrid group). In each group, a 5 min electrocardiogram (ECG) obtained before and after the CA were analyzed. Time and frequency domain parameters were evaluated. Vagal responses (VR) during CA were observed in 12 (60%) patients in the GP group; however, in the Hybrid group, VR was not observed in any of the patients during CA. The change in normalized power in the low frequency (LF) component and the ratio between the LF and high frequency (LF/HF ratio) components of the HRV spectra, before and after ablation, were statistically significant in the GP group (3.3±2.6 before vs. 1.8±1.9 after ablation) but unchanged, before or after CA, in the Hybrid group. GP ablation in patients subsequent to TA has a little influence on HRV parameters, which could be explained by GP damage during the preceding TA.

Relationship between frequency spectrum of heart rate variability and autonomic nervous activities during sleep in newborns

IntroductionWe analyzed the frequency spectrum of two neonatal sleep stages, namely active sleep and quiet sleep, and the relationship between these sleep stages and autonomic nervous activity in 74 newborns and 16 adults as a comparison. MethodActive and quiet sleep were differentiated by electroencephalogram (EEG) patterns, eye movements, and respiratory wave patterns; autonomic activity was analyzed using the RR interval of simultaneously recorded electrocardiogram (ECG) signals. Power values (LFa, absolute low frequency; HFa, absolute high frequency), LFa/HFa ratio, and the values of LFn (normalized low frequency) and HFn (normalized high frequency) were obtained. Synchronicity between the power value of HFa and the LFa/HFa ratio during active and quiet sleep was also examined by a new method of chronological demonstration of the power values of HFa and LFa/HFa. ResultsWe found that LFa, HFa and the LFa/HFa ratio during active sleep were significantly higher than those during quiet sleep in newborns; in adults, on the other hand, the LFa/HFa ratio during rapid eye movement (REM) sleep, considered as active sleep, was significantly higher than that during non-REM sleep, considered as quiet sleep, and HFa values during REM sleep were significantly lower than those during non-REM sleep. LFn during quiet sleep in newborns was significantly lower than that during active sleep. Conversely, HFn during quiet sleep was significantly higher than that during active sleep. Analysis of the four classes of gestational age groups at birth indicated that autonomic nervous activity in a few preterm newborns did not reach the level seen in full-term newborns. Furthermore, the power value of HFa and the LFa/HFa ratio exhibited reverse synchronicity. ConclusionThese results indicate that the autonomic patterns in active and quiet sleep of newborns are different from those in REM and non-REM sleep of adults and may be develop to the autonomic patterns in adults, and that parasympathetic activity is dominant during quiet sleep as compared to active sleep from the results of LFn and HFn in newborns. In addition, in some preterm infants, delayed development of the autonomic nervous system can be determined by classifying the autonomic nervous activity pattern of sleep stages.

Conditional adaptive Bayesian spectral analysis of nonstationary biomedical time series.

Many studies of biomedical time series signals aim to measure the association between frequency-domain properties of time series and clinical and behavioral covariates. However, the time-varying dynamics of these associations are largely ignored due to a lack of methods that can assess the changing nature of the relationship through time. This article introduces a method for the simultaneous and automatic analysis of the association between the time-varying power spectrum and covariates, which we refer to as conditional adaptive Bayesian spectrum analysis (CABS). The procedure adaptively partitions the grid of time and covariate values into an unknown number of approximately stationary blocks and nonparametrically estimates local spectra within blocks through penalized splines. CABS is formulated in a fully Bayesian framework, in which the number and locations of partition points are random, and fit using reversible jump Markov chain Monte Carlo techniques. Estimation and inference averaged over the distribution of partitions allows for the accurate analysis of spectra with both smooth and abrupt changes. The proposed methodology is used to analyze the association between the time-varying spectrum of heart rate variability and self-reported sleep quality in a study of older adults serving as the primary caregiver for their ill spouse.

Relationships between the EEG θ- and β-parameters and heart rate variability during human cognitive performance

We studied the dynamics of spectral coherence characteristics of the EEG θ-, β1-, and β2-activity and the heart rate variability (HRV) in subjects performing cognitive tests. We found an association between the HRV parameters in the process of cognitive activity and the coherence of potentials in the EEG θ-, β1-, and β2-bands. The heart rate parameters in the baseline state and during the test performance best correlated with the levels of the right-hemispheric coherence of potentials in the θ-, β1-, and β2-bands of the baseline EEG (eyes closed). The higher coherence levels corresponded to lower values of the mean time of RR intervals (RRNN), coefficient of variation (CV), total power (TP), the power of the high-frequency (HF) and low-frequency (LF) components in the HRV spectrum. During the performance of the test, higher coherence values in the EEG θ-bands with the focus in the right temporal lead corresponded to higher LF/HF values reflecting the predominance of sympathetic effects on heart rate.

Remote ischemic preconditioning triggers changes in autonomic nervous system activity: implications for cardioprotection

Cardioprotective efficacy of remote ischemic preconditioning (RIPC) remains controversial. Experimental studies investigating RIPC have largely monitored cardiovascular changes during index ischemia and reperfusion with little work investigating changes during RIPC application. This work aims to identify cardiovascular changes associated with autonomic nervous system (ANS) activity during RIPC and prior to index ischemia. RIPC was induced in anesthetized male C57/Bl6 mice by four cycles of 5 min of hindlimb ischemia using inflated cuff (200 mmHg) followed by 5 min reperfusion. Electrocardiography (ECG) and microcirculatory blood flow in both hindlimbs were recorded throughout RIPC protocol. Heart rate variability (HRV) analysis was performed using ECG data. Hearts extracted at the end of RIPC protocol were used either for measurement of myocardial metabolites using high‐performance liquid chromatography or for Langendorff perfusion to monitor function and injury during 30 min index ischemia and 2 h reperfusion. Isolated‐perfused hearts from RIPC animals had significantly less infarct size after index ischemia and reperfusion (34 ± 5% vs. 59 ± 7%; mean ± SE P < 0.05). RIPC protocol was associated with increased heart rate measured both in ex vivo and in vivo. Frequency ratio of HRV spectra was altered in RIPC compared to control. RIPC was associated with a standard hyperemic response in the cuffed‐limb but there was a sustained reduction in blood flow in the uncuffed contralateral limb. RIPC hearts (prior to index ischemia) had significantly lower phosphorylation potential and energy charge compared to the control group. In conclusion, RIPC is associated with changes in ANS activity (heart rate, blood flow, HRV) and mild myocardial ischemic stress that would contribute to cardioprotection.

INFLUENCE OF MAGNETIC STORM ON THE HEMODYNAMIC PARAMETERS AND HEART RATE VARIABILITY IN NORMOTENSIVE WISTAR RATS

Objective. The aim of this work was to examine influence of the geomagnetic storms on the hemodynamic parameters and heart rate variability in normotensive rats. Design and methods . Studies were conducted in Wistar male rats. Registration of systolic blood pressure, beat-to-beat interval and components of heart rate variability were conducted in the days of the geomagnetic storm and in the days, when the Earth’s magnetic field was calm. Results. We found that, in the days of geomagnetic disturbances sympathetic component of spectrum of heart rate variability decreased, simultaneously we observed a tendency to increase of blood pressure and average of heart rate. Conclusions . We have suggested, that decline in activity of the sympathetic nervous system contributes to maintain of a normal level of hemodynamic constants during geomagnetic storm.

ВЛИЯНИЕ ВЫСОКОАКТИВНОЙ АНТИРЕТРОВИРУСНОЙ ТЕРАПИИ НА СПЕКТРАЛЬНЫЕ ПОКАЗАТЕЛИ ВАРИАБЕЛЬНОСТИ РИТМА СЕРДЦА У БОЛЬНЫХ ВИЧ-ИНФЕКЦИЕЙ

Objective: To study the frequency of heart rate variability (HRV) in patients with HIV infection 12 weeks after highly active antiretroviral therapy. Methods: Examined 95 persons aged 24 to 52 years. The main group consisted of 60 patients with HIV infection: 49 men (57.5%) and 11 women (42.5%). The control group included 35 HIV-infected patients of comparable sex and age. A study of the spectral parameters of HRV carried out with the help of the apparatus VARIKARD 2.51 (Russia). Results: After highly active antiretroviral therapy, against the background of improvement in the overall clinical state, HIV-positive patients showed a positive trend from the HRV spectra: total power (TP) increased by 5% (from 1469.9 ± 52.4 up to 1539.1 ± 54.1 ms2) due to an increase in the contribution of the parasympathetic part of the vegetative nervous system. After 3 months of the study, in the patients of the comparison group, against the background of worsening of the overall clinical condition, negative dynamics observed on the part of the HRV frequency parameters. TP decreased by 12% due to increased sympathetic involvement and decreased parasympathetic parts of the vegetative nervous system. Conclusion: The obtained results showed improvement of adaptation processes in HIV-infected patients against the background of highly active antiretroviral therapy. Keywords: HIV infection, heart rate variability, spectral indices, highly active antiretroviral therapy.

Heart rate variability changes during and after the practice of bhramari pranayama

Background:Yoga is an ancient Indian science as well as the way of life. Pranayama is one of the most important yogic practices. Bhramari pranayama was shown to produce a reduction in blood pressure after the practice and thus reported to produce parasympathetic activity. However, there are no known studies reported the heart rate variability (HRV) changes either during or after the practice of Bhramari. Hence, this study aims at evaluating the HRV changes during and after the practice.Materials and Methods:Sixteen (9 males, 7 females) healthy volunteers with the mean ± standard deviation age of 23.50 ± 3.01 years were recruited. All the subjects performed Bhramari pranayama for the duration of 5 min. Assessments were taken before, during, and immediately after the practice of pranayama. Statistical analysis was performed using students paired samples t-test, Wilcoxon signed-ranks test and repeated measures of analysis of variance and Post-hoc analysis with Bonferroni adjustment for multiple comparisons.Results:Results of this study showed a significant increase in HR and low frequency spectrum of HRV and a significant reduction in high frequency spectrum of HRV during the practice of Bhramari which revert to normal after the practice.Conclusion:Results of this study suggests that there might be a parasympathetic withdrawal during the practice of Bhramari. However, further studies are required to warrant the findings of this study.

Exercise tolerance in obstructive sleep apnea-hypopnea (OSAH), before and after CPAP treatment: Effects of autonomic dysfunction improvement

BackgroundObstructive sleep apnea hypopnea (OSAH) is associated with decreased exercise tolerance and autonomic abnormalities and represents a risk for cardiovascular diseases. The aim of the study was to evaluate the effects of CPAP on cardiovascular autonomic abnormalities and exercise performance in patients with OSAH without changes in lifestyle and body weight during treatment. MethodsTwelve overweight subjects with OSAH underwent anthropometric measures, autonomic cardiovascular and incremental symptom-limited cardio-respiratory exercise tests before and after two months of treatment with CPAP. ResultsLower frequency component of power spectrum of heart rate variability (59.5±24.2 msec2 vs 43.2±25.9 msec2; p<0.05) and improvements of maximal workload (99.3±13.5 vs 108.3±16.8%pred.; p<0.05) and peak oxygen consumption (95.3±7.6 vs 105.5±7.9%pred.; p<0.05) were observed in these patients after CPAP, being their BMI unchanged. ConclusionsCPAP-induced decrease of sympathetic hyperactivity is associated with better tolerance to the effort in OSAH patients that did not change their BMI and lifestyle, suggesting that OSAH limits per se the exercise capacity.

Influence on human body of audibility amplitude modulation low-frequency noise in residential environment

Low-frequency noise of about 100 Hz including audible frequency is positioned as one of the factors of environmental problem. First, this paper describes countermeasures of psychological complaint by low-frequency noise generated by residential environment in Japan published in the Ministry of the Environment. Next, we experimentally examined the human body influence of audibility amplitude modulation low frequency noise (AMLFN) on the psychological and physiological response measured by whole-body exposure. The AMLFN used by this research fluctuated the fluctuation cycle of the carrier wave and the sound pressure level periodically by the amplitude modulation. The measuring objects of the psychological response are an annoyance by the psychological questionnaire and an impression evaluation by the semantic differential method. The measuring objects of the physiological response are a salivary amylase activity, a R-R interval, and a power spectrum of heart rate variability. The stress reaction by AMLFN exposure was examined from these measurement results. From these experimental results, the stress reactions during AMLFN exposure were tendency increased with an increase of the modulation depth of the sound pressure level and a decrease of the fluctuation cycle, and the annoyance was tendency increased with a decrease of the carrier frequency.

Sleep-related changes in cardiovascular autonomic regulation in left coronary artery ligation rats: Neural mechanism facilitating arrhythmia after myocardial infarction

BackgroundAutonomic imbalance with increased sympathetic and decreased parasympathetic activities is observed in patients after myocardial infarction (MI). We aimed to investigate sleep-related changed in autonomic regulation in left coronary artery (LCA) ligation rats. MethodsWireless transmission of polysomnographic recording was performed in sham and LCA ligation male rats during normal daytime sleep with and without atenolol treatment. Spectral analyses of the electroencephalogram (EEG) and electromyogram (EMG) were evaluated to define active waking (AW), quiet and paradoxical sleeps (QS, PS). Cardiac autonomic activities were measured by analyzing the power spectrum of heart rate variability (HRV). EEG, EMG and HRV were recorded over 6h for consecutive 3days in all groups. ResultsIn LCA ligation group, there were higher LF and LF/HF ratio on QS phase, but not AW and PS phases, compared to atenolol treated sham and LCA ligation groups, respectively. The HF component was not significantly changed on all groups in both sleep and awake phases. Sleep interruption was more frequent in LCA ligation rats compared to sham, and it was not found in LCA ligation with atenolol treatment group. Increased AW, PS and decreased QS time were noted in LCA ligation group, compared to sham and it was restored to baseline in LCA ligation with atenolol treatment group. ConclusionsOur results demonstrate significant sleep fragmentations with sympathetic hyperactivity during QS stages after MI, and atenolol could restore the autonomic dysfunction and sleep disturbance. The finding explains the cause of sleep-related fetal arrhythmia and sudden cardiac death after MI.

MECHANISMS OF INTERACTION BETWEEN THE CIRCADIAN SYSTEM, EEG RHYTHMS AND REGULATION OF VEGETATIVE PROCESSES

Aim - to investigate the dynamics of EEG rhythms and vegetative responses in human on a short-term exposure of the retina to the blue light in the spectrum of maximum sensitivity of circadian photoreceptors during daytime wake. Materials and methods. EEG parameters (BP-010302 BrainАmp Standart128), blood pressure and heart rate variability (HRV) were recorded at 22 volunteer students aged 18-20 years before, after and during the 2-5 minute stimulation of circadian retinal receptors by blue light with maximum wavelength of 480 nm. Results. The stimulation of the photoreceptors of the circadian system correlates with the dynamics of the following neurovegetative processes: desynchronization in beta2- and gamma EEG rhythms, synchronization in teta2- and alpha1-frequency bands; increase in the duration of RR interval and power of low-frequency component of HRV, decrease in the percentage of high-frequency oscillation spectrum of HRV and decrease in systolic blood pressure. Termination of the stimulation of circadian system photoreceptors causes the transformation of EEG rhythms response with predominance of synchronization in low (teta1, teta 2), medium (alpha 1, alpha 2, alfa 3) and high frequency (beta 2) bands. Conclusion. The paper shows the possibility of quick correction of human vegetative background by controlling the circadian system. The human circadian clock is likely to control functional brain activity involving beta 2- and gamma-quantization.

Reduced power spectra of heart rate variability are correlated with anxiety in patients with mild traumatic brain injury

Anxiety is one of the most frequently diagnosed emotional disorders after a mild traumatic brain injury (mTBI); however, predictors of anxiety after an mTBI remain uncertain. Recent research indicated that anxiety is associated with abnormalities in the autonomic nervous system (ANS) which can be evaluated by a power spectral analysis of heart rate variability (HRV). In this study, we investigated whether a frequency-domain analysis of HRV could correlate with the occurrence of anxiety in mTBI patients. We recruited 165 Taiwanese patients diagnosed with an mTBI and 82 volunteer healthy controls from three affiliated hospitals of Taipei Medical University during 2010–2014. The Beck Anxiety Inventory (BAI) was assessed at the 1st, 6th, and 12th weeks. We found that mTBI patients were more vulnerable to anxiety compared to healthy controls. The power spectral density of HRV was significantly lower in mTBI patients than in healthy controls. A correlation analysis indicated that anxiety was negatively significantly correlated with low- and high-frequency power at the 6th week. Our study suggests the clinical usefulness of HRV as a potential noninvasive tool for evaluating later anxiety in mTBI patients.

Decomposition of Heart Rate Variability Spectrum into a Power-Law Function and a Residual Spectrum.

The power spectral density (PSD) of heart rate variability (HRV) contains a power-law relationship that can be obtained by plotting the logarithm of PSD against the logarithm of frequency. The PSD of HRV can be decomposed mathematically into a power-law function and a residual HRV (rHRV) spectrum. Almost all rHRV measures are significantly smaller than their corresponding HRV measures except the normalized high-frequency power (nrHFP). The power-law function can be characterized by the slope and Y-intercept of linear regression. Almost all HRV measures except the normalized low-frequency power have significant correlations with the Y-intercept, while almost all rHRV measures except the total power [residual total power (rTP)] do not. Though some rHRV measures still correlate significantly with the age of the subjects, the rTP, high-frequency power (rHFP), nrHFP, and low-/high-frequency power ratio (rLHR) do not. In conclusion, the clinical significances of rHRV measures might be different from those of traditional HRV measures. The Y-intercept might be a better HRV measure for clinical use because it is independent of almost all rHRV measures. The rTP, rHFP, nrHFP, and rLHR might be more suitable for the study of age-independent autonomic nervous modulation of the subjects.

Autonomic providing cardiac rhythm of middle-aged women with long-term regular training experience of aerobic orientation

Aim. To study the influence of regular training with aerobic orientation on heart rate variability of middle-aged women with long-term training experience. Materials and methods. In the work the results of research autonomic providing cardiac rhythm of 19 women, who were divided into two studied groups are presented. The first study group consisted of 10 women who had experience of regular training (3 times a week) aerobic orientation from 3 to 5 years, the average age of this group of women was 37,9±5,9 years. The second study group consisted of 9 women with regular training experience with aerobic orientation over 10 years, the average age of women – 44,6±5,5 years. At this stage we defined the specific features autonomic heart providing, that was characterized on the basis of the analysis of heart rhythm variability results. For this purpose it was used the device – spiroarteriocardiorhythmography, which in simultaneous mode register defines the parameters of heart rate, systolic and diastolic blood pressure for each heart reduction. According to data the measuring of sequences cardiac rhythm, systolic and diastolic blood pressure variability and data respiratory ventilation was conducted by Fourier's spectral analysis, which determines the capacity of regulatory influences on three frequency ranges: very-low-frequency (VLF, 0–0,04 Hz), low-frequency (LF, 0,04–0,15 Hz) and high-frequency (HF, 0,15–0,4 Hz), what are measured in the absolute values of power (ms 2 ). Additionally there was a spectral method determined by data of sensitivity arterial baroreflex (SBR, ms/mmHg) – α-coefficient, what calculated in ranges high (SBR HF ) and low (SBR LF ) frequencies, connecting with a total activity, activity of over-segmental structures, parasympathetic and sympathetic branches of autonomic nervous system. Results. Research results showed difference in heart rate variability of parameters observed only for high-frequency components, which was significantly (p<0,05) lower in second study group. In this case, women of that group had a tendency to a slight sympathetic predominance and in the first study group– parasympathetic influences. As for the other components the power spectrum of heart rate variability, it should be noted that there is a certain tendency that certifies reduction of general and all constituents power spectrum of heart rate variability in the second study group. Results of determination of sensitivity arterial baroreflex of women demonstrate the positive impact of training on the mechanisms autonomic regulation in the high-frequency range, which because of long-term experience significantly reduced. It can be asserted that increasing the term of training with aerobic orientation leads to increased low-frequency (sympathicotonic) but decreased high-frequency (vagotonics) effect on cardiac rhythm. Conclusions. The studies which were conducted revealed, that women in second study group have, unreliable, but a significant increase in activity of regulatory impact in very-low-frequency range, that in our opinion could be predefined by physiological characteristics of an organism at the age that group of women. The biggest changes come from the decrease in activity of regulation in high-frequency range with increasing the term of training. The latter is confirmed by probable decrease in autonomous control for the indicators of sensitivity arterial baroreflex in a high-frequency range

A comprehensive assessment of cardiovascular autonomic control using photoplethysmograms recorded from the earlobe and fingers

We compare the spectral indices of photoplethysmogram variability (PPGV) estimated using photoplethysmograms recorded from the earlobe and the middle fingers of the right and left hand and analyze their correlation with similar indices of heart rate variability (HRV) in 30 healthy subjects (26 men) aged 27 (25, 29) years (median with inter-quartile ranges) at rest and under the head-up tilt test. The following spectral indices of PPGV and HRV were compared: mean heart rate (HR), total spectral power (TP), high-frequency (HF) and low-frequency (LF) ranges of TP in percents (HF% and LF%), LF/HF ratio, and spectral coherence. We assess also the index S of synchronization between the LF oscillations in HRV and PPGV.The constancy of blood pressure (BP) and moderate increase of HR under the tilt test indicate the presence of fast processes of cardiovascular adaptation with the increase of the sympathetic activity in studied healthy subjects. The impact of respiration on the PPGV spectrum (accessed by HF%) is less than on the HRV spectrum. It is shown that the proportion of sympathetic vascular activity (accessed by LF%) is constant in the PPGV of three analyzed PPGs during the tilt test. The PPGV for the ear PPG was less vulnerable to breathing influence accessed by HF% (independently from body position) than for PPGs from fingers. We reveal the increase of index S under the tilt test indicating the activation of interaction between the heart and distal vessels. The PPGV spectra for finger PPGs from different hands are highly coherent, but differ substantially from the PPGV spectrum for the ear PPG. We conclude that joint analysis of frequency components of PPGV (for the earlobe and finger PPGs of both hands) and HRV and assessment of their synchronization provide additional information about cardiovascular autonomic control.