scholarly journals Multiscale Information Decomposition Dissects Control Mechanisms of Heart Rate Variability at Rest and During Physiological Stress

Entropy ◽  
2019 ◽  
Vol 21 (5) ◽  
pp. 526 ◽  
Author(s):  
Jana Krohova ◽  
Luca Faes ◽  
Barbora Czippelova ◽  
Zuzana Turianikova ◽  
Nikoleta Mazgutova ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Scales ◽  
Information Transfer ◽  
Physiological Stress ◽  
Short Time Scale ◽  
Control Mechanisms ◽  
Sinus Arrhythmia ◽  
Long Time ◽  
Short Time

Heart rate variability (HRV; variability of the RR interval of the electrocardiogram) results from the activity of several coexisting control mechanisms, which involve the influence of respiration (RESP) and systolic blood pressure (SBP) oscillations operating across multiple temporal scales and changing in different physiological states. In this study, multiscale information decomposition is used to dissect the physiological mechanisms related to the genesis of HRV in 78 young volunteers monitored at rest and during postural and mental stress evoked by head-up tilt (HUT) and mental arithmetics (MA). After representing RR, RESP and SBP at different time scales through a recently proposed method based on multivariate state space models, the joint information transfer T RESP , SBP → RR is decomposed into unique, redundant and synergistic components, describing the strength of baroreflex modulation independent of respiration ( U SBP → RR ), nonbaroreflex ( U RESP → RR ) and baroreflex-mediated ( R RESP , SBP → RR ) respiratory influences, and simultaneous presence of baroreflex and nonbaroreflex respiratory influences ( S RESP , SBP → RR ), respectively. We find that fast (short time scale) HRV oscillations—respiratory sinus arrhythmia—originate from the coexistence of baroreflex and nonbaroreflex (central) mechanisms at rest, with a stronger baroreflex involvement during HUT. Focusing on slower HRV oscillations, the baroreflex origin is dominant and MA leads to its higher involvement. Respiration influences independent on baroreflex are present at long time scales, and are enhanced during HUT.

scholarly journals Nonlinearities of heart rate variability in animal models of impaired cardiac control: contribution of different time scales

2017 ◽  
Vol 123 (2) ◽  
pp. 344-351 ◽  
Author(s):  
Luiz Eduardo Virgilio Silva ◽  
Renata Maria Lataro ◽  
Jaci Airton Castania ◽  
Carlos Alberto Aguiar Silva ◽  
Helio Cesar Salgado ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Scales ◽  
Multiscale Entropy ◽  
Time Frequency ◽  
Cardiac Control ◽  
Long Time ◽  
Nonlinear Features ◽  
Short Time

Heart rate variability (HRV) has been extensively explored by traditional linear approaches (e.g., spectral analysis); however, several studies have pointed to the presence of nonlinear features in HRV, suggesting that linear tools might fail to account for the complexity of the HRV dynamics. Even though the prevalent notion is that HRV is nonlinear, the actual presence of nonlinear features is rarely verified. In this study, the presence of nonlinear dynamics was checked as a function of time scales in three experimental models of rats with different impairment of the cardiac control: namely, rats with heart failure (HF), spontaneously hypertensive rats (SHRs), and sinoaortic denervated (SAD) rats. Multiscale entropy (MSE) and refined MSE (RMSE) were chosen as the discriminating statistic for the surrogate test utilized to detect nonlinearity. Nonlinear dynamics is less present in HF animals at both short and long time scales compared with controls. A similar finding was found in SHR only at short time scales. SAD increased the presence of nonlinear dynamics exclusively at short time scales. Those findings suggest that a working baroreflex contributes to linearize HRV and to reduce the likelihood to observe nonlinear components of the cardiac control at short time scales. In addition, an increased sympathetic modulation seems to be a source of nonlinear dynamics at long time scales. Testing nonlinear dynamics as a function of the time scales can provide a characterization of the cardiac control complementary to more traditional markers in time, frequency, and information domains. NEW & NOTEWORTHY Although heart rate variability (HRV) dynamics is widely assumed to be nonlinear, nonlinearity tests are rarely used to check this hypothesis. By adopting multiscale entropy (MSE) and refined MSE (RMSE) as the discriminating statistic for the nonlinearity test, we show that nonlinear dynamics varies with time scale and the type of cardiac dysfunction. Moreover, as complexity metrics and nonlinearities provide complementary information, we strongly recommend using the test for nonlinearity as an additional index to characterize HRV.

scholarly journals Stratified Flows over and around Long Dynamically Tall Mountain Ridges

2019 ◽  
Vol 76 (5) ◽  
pp. 1265-1287 ◽  
Author(s):  
Arjun Jagannathan ◽  
Kraig Winters ◽  
Laurence Armi
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Stratified Flows ◽  
Half Width ◽  
Short Time Scale ◽  
Late Time ◽  
Low Level ◽  
Long Time ◽  
Flow Splitting ◽  
Short Time

Abstract Uniformly stratified flows approaching long and dynamically tall ridges develop two distinct flow components over disparate time scales. The fluid upstream and below a “blocking level” is stagnant in the limit of an infinite ridge and flows around the sides when the ridge extent is finite. The streamwise half-width of the obstacle at the blocking level arises as a natural inner length scale for the flow, while the excursion time over this half-width is an associated short time scale for the streamwise flow evolution. Over a longer time scale, low-level horizontal flow splitting leads to the establishment of an upstream layerwise potential flow beneath the blocking level. We demonstrate through numerical experiments that for sufficiently long ridges, crest control and streamwise asymmetry are seen on both the short and long time scales. On the short time scale, upstream blocking is established quickly and the flow is well described as a purely infinite-ridge overflow. Over the long time scale associated with flow splitting, low-level flow escapes around the sides, but the overflow continues to be hydraulically controlled and streamwise asymmetric in the neighborhood of the crest. We quantify this late-time overflow by estimating its volumetric transport and then briefly demonstrate how this approach can be extended to predict the overflow across nonuniform ridge shapes.

scholarly journals Multiscale entropy analysis of heart rate variability in heart failure, hypertensive, and sinoaortic-denervated rats: classical and refined approaches

2016 ◽  
Vol 311 (1) ◽  
pp. R150-R156 ◽  
Author(s):  
Luiz Eduardo Virgilio Silva ◽  
Renata Maria Lataro ◽  
Jaci Airton Castania ◽  
Carlos Alberto Aguiar da Silva ◽  
Jose Fernando Valencia ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Scales ◽  
Complexity Analysis ◽  
Respiratory Control ◽  
Cardiovascular Regulation ◽  
Multiscale Entropy ◽  
Conscious Animal ◽  
Long Time

The analysis of heart rate variability (HRV) by nonlinear methods has been gaining increasing interest due to their ability to quantify the complexity of cardiovascular regulation. In this study, multiscale entropy (MSE) and refined MSE (RMSE) were applied to track the complexity of HRV as a function of time scale in three pathological conscious animal models: rats with heart failure (HF), spontaneously hypertensive rats (SHR), and rats with sinoaortic denervation (SAD). Results showed that HF did not change HRV complexity, although there was a tendency to decrease the entropy in HF animals. On the other hand, SHR group was characterized by reduced complexity at long time scales, whereas SAD animals exhibited a smaller short- and long-term irregularity. We propose that short time scales (1 to 4), accounting for fast oscillations, are more related to vagal and respiratory control, whereas long time scales (5 to 20), accounting for slow oscillations, are more related to sympathetic control. The increased sympathetic modulation is probably the main reason for the lower entropy observed at high scales for both SHR and SAD groups, acting as a negative factor for the cardiovascular complexity. This study highlights the contribution of the multiscale complexity analysis of HRV for understanding the physiological mechanisms involved in cardiovascular regulation.

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

scholarly journals Predictive Value of Subacute Heart Rate Variability for Determining Outcome Following Adolescent Concussion

2021 ◽  
Vol 10 (1) ◽  
pp. 161
Author(s):  
Colt A. Coffman ◽  
Jacob J. M. Kay ◽  
Kat M. Saba ◽  
Adam T. Harrison ◽  
Jeffrey P. Holloway ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Cognitive Performance ◽  
Predictive Value ◽  
System Integration ◽  
Sports Medicine ◽  
Clinical Symptoms ◽  
Physiological Stress ◽  
Neurological Dysfunction ◽  
Neurobehavioral Function

Objective assessments of concussion recovery are crucial for facilitating effective clinical management. However, predictive tools for determining adolescent concussion outcomes are currently limited. Research suggests that heart rate variability (HRV) represents an indirect and objective marker of central and peripheral nervous system integration. Therefore, it may effectively identify underlying deficits and reliably predict the symptomology following concussion. Thus, the present study sought to evaluate the relationship between HRV and adolescent concussion outcomes. Furthermore, we sought to examine its predictive value for assessing outcomes. Fifty-five concussed adolescents (12–17 years old) recruited from a local sports medicine clinic were assessed during the initial subacute evaluation (within 15 days postinjury) and instructed to follow up for a post-acute evaluation. Self-reported clinical and depressive symptoms, neurobehavioral function, and cognitive performance were collected at each timepoint. Short-term HRV metrics via photoplethysmography were obtained under resting conditions and physiological stress. Regression analyses demonstrated significant associations between HRV metrics, clinical symptoms, neurobehavioral function, and cognitive performance at the subacute evaluation. Importantly, the analyses illustrated that subacute HRV metrics significantly predicted diminished post-acute neurobehavioral function and cognitive performance. These findings indicate that subacute HRV metrics may serve as a viable predictive biomarker for identifying underlying neurological dysfunction following concussion and predict late cognitive outcomes.

249 Overnight heart rate variability depends on age, gender, and day of the week: a field observation using a smart bed platform

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A100-A101
Author(s):  
Shawn Barr ◽  
Kwanghyun Sohn ◽  
Gary Garcia
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Physiological Stress ◽  
Large Population ◽  
Population Level ◽  
Large Set ◽  
Sleep State ◽  
Cross Sectional ◽  
Day Of The Week ◽  
Broad Interest

Abstract Introduction Heart rate variability (HRV) is commonly used to assess the activity of the autonomic nervous system (ANS). ANS function changes, reflected in HRV, result from factors including lifestyle, aging, cardiorespiratory illnesses, sleep state, and physiological stress. Despite broad interest in HRV, few studies have established normative overnight HRV values for a large population. To better understand population level HRV changes, ecologically-valid, overnight sleep SDNN (standard deviation of all normal heartbeat intervals, lower HRV is reflected by lower SDNN) values have been analyzed for a large sample of Sleep Number 360 smart bed users. Methods Overnight SDNN values were obtained over the course of 18.2M sleep sessions from 379,225 sleepers (48 ± 14.7 sessions/user). 50.9 percent of sleepers were female. The age was normally distributed with mean ± SD of 52.8 ± 12.7 years (range 21 to 84). Heartbeat intervals used to compute SDNN were extracted from a ballistocardiogram (BCG). BCG-based HRV estimation during sleep has previously been validated against ECG-based HRV with an R-square of 0.5. Results Using a Generalized Linear Model, significant cross-sectional associations with SDNN were observed for three variables of interest: age, gender, and day-of-the-week. For sleepers under 50, SDNN declined at a rate of about 2.1 ms/year, then leveled off for sleepers aged 50-65, and increased slightly thereafter. Women under 50 displayed lower, more slowly declining, SDNN values than men, but this trend reversed for sleepers over 50. Throughout the week, SDNN values followed a U-shaped (women) or L-shaped (men) pattern, where values were highest during the weekend and lowest at mid-week. Conclusion Using a smart bed to unobtrusively measure overnight SDNN values for a large set of sleepers in an ecologically valid environment, reveals significant effects of age, gender, and day of the week on overnight SDNN. Support (if any):

On the fractal nature of heart rate variability in humans: effects of respiratory sinus arrhythmia

1995 ◽  
Vol 269 (2) ◽  
pp. H480-H486 ◽  
Author(s):  
Y. Yamamoto ◽  
J. O. Fortrat ◽  
R. L. Hughson
Keyword(s):  
Heart Rate ◽  
Time Series ◽  
Heart Rate Variability ◽  
Coarse Graining ◽  
Resting Heart Rate ◽  
Breathing Frequency ◽  
Fractal Nature ◽  
Sinus Arrhythmia ◽  
Spectral Exponent ◽  
Random Fractal

The purpose of the present study was to investigate the basic fractal nature of the variability in resting heart rate (HRV), relative to that in breathing frequency (BFV) and tidal volume (TVV), and to test the hypothesis that fractal HRV is due to the fractal BFV and/or TVV in humans. In addition, the possible fractal nature of respiratory volume curves (RVC) and HRV was observed. In the first study, eight subjects were tested while they sat quietly in a comfortable chair for 60 min. Beat-to-beat R-R intervals, i.e., HRV, and breath-by-breath BFV and TVV were measured. In the second study, six subjects were tested while they were in the supine position for 20-30 min. The RVC was monitored continuously together with HRV. Coarse-graining spectral analysis (Yamamoto, Y., and R. L. Hughson, Physica D 68: 250-264, 1993) was applied to these signals to evaluate the percentage of random fractal components in the time series (%Fractal) and the spectral exponent (beta), which characterizes irregularity of the signals. The estimates of beta were determined for each variable only over the range normally used to evaluate HRV. Values for %Fractal and beta of both BFV and TVV were significantly (P < 0.05) greater than those for HRV. In addition, there was no significant (P > 0.05) correlation between the beta values of HRV relative to either BFV (r = 0.14) or TVV (r = 0.34). RVC showed a smooth oscillation as compared with HRV; %Fractal for RVC (42.3 +/- 21.7%, mean +/- SD) was significantly (P < 0.05) lower than that for HRV (78.5 +/- 4.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Opposite of Stress

2020 ◽  
Vol 67 (2) ◽  
pp. 150-159
Author(s):  
Maria Meier ◽  
Eva Unternaehrer ◽  
Sabine M. Schorpp ◽  
Maya Wenzel ◽  
Annika Benz ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Divergent Thinking ◽  
Area Under The Curve ◽  
Vagal Tone ◽  
Positive Association ◽  
Control Group ◽  
Creative Potential ◽  
Sinus Arrhythmia ◽  
Healthy Female

Abstract. Cognition is affected by psychophysiological states. While the influence of stress on cognition has been investigated intensively, less studies have addressed how the opposite of stress, a state of relaxation, affects cognition. We investigated whether the extent of parasympathetic activation is positively related to divergent thinking. Sixty healthy female participants were randomly allocated to a standardized vagus nerve massage ( n = 19), a standardized soft shoulder massage ( n = 22), or a resting control group ( n = 19). Subsequently, participants completed the Alternative Uses Test (AUT), a measure of divergent thinking. Respiratory sinus arrhythmia (RSA), a vagally mediated heart rate variability component, was monitored throughout the experiment. The area under the curve with respect to the increase was calculated for RSA trajectories as an indicator of vagal tone during the relaxing intervention. Regressions tested the effect of vagal tone on AUT outcomes. We found an association between vagal tone and subsequent AUT outcomes. Yet, this association was no longer significant when controlling for the effect of the creative potential of an individual, which was strongly related to AUT outcomes. Being exploratory, we found a positive association between creative potential and vagal tone. These results imply that creative potential might be related to the capacity to relax.

A Case Report on Heart Rate Variability Biofeedback and Postconcussion Syndrome: Healing the Autonomic Nervous System

Biofeedback ◽  
2021 ◽  
Vol 49 (4) ◽  
pp. 86-88
Author(s):  
Leah M. Lagos
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Amplitude ◽  
Regulatory Control ◽  
Control Mechanisms ◽  
Postconcussion Syndrome ◽  
Heart Rate Variability Biofeedback ◽  
The Mind ◽  
The Brain ◽  
Cardiovascular Functions

Postconcussion syndrome is a devastating condition of the mind, body, and even personality. Mounting research demonstrates that heart rate variability biofeedback can help the concussed individual in three critical ways: (a) eliciting high amplitude oscillations in cardiovascular functions and thereby strengthening self-regulatory control mechanisms; (b) restoring autonomic balance; and (c) increasing the afferent impulse stream from the baroreceptors to restore balance between inhibitory and excitatory processes in the brain.

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