Medicine › Cardiology and Cardiovascular Medicine

Heart Rate Variability and Autonomic Control

Works Count: 100452

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Description

This cluster of papers focuses on the analysis, applications, and implications of heart rate variability (HRV) in understanding autonomic nervous system function, physiological time series analysis using entropy methods, neurovisceral integration, its role as a marker of stress and health, and its associations with cardiovascular disease, emotion regulation, and baroreflex sensitivity. The cluster also covers the impact of HRV on various health conditions such as diabetes, depression, anxiety disorders, and mortality prediction.

Keywords

Heart Rate Variability; Autonomic Nervous System; Physiological Time Series; Entropy Analysis; Neurovisceral Integration; Cardiovascular Disease; Emotion Regulation; Stress Marker; Baroreflex Sensitivity; Vagal Tone

Physiological aspects of primary hypertension.

1982-04-01

Björn Folkow

Physiological time-series analysis: what does regularity quantify?

1994-04-01

Steve Pincus , Ary L. Goldberger

Approximate entropy (ApEn) is a recently developed statistic quantifying regularity and complexity that appears to have potential application to a wide variety of physiological and clinical time-series data. The focus … Approximate entropy (ApEn) is a recently developed statistic quantifying regularity and complexity that appears to have potential application to a wide variety of physiological and clinical time-series data. The focus here is to provide a better understanding of ApEn to facilitate its proper utilization, application, and interpretation. After giving the formal mathematical description of ApEn, we provide a multistep description of the algorithm as applied to two contrasting clinical heart rate data sets. We discuss algorithm implementation and interpretation and introduce a general mathematical hypothesis of the dynamics of a wide class of diseases, indicating the utility of ApEn to test this hypothesis. We indicate the relationship of ApEn to variability measures, the Fourier spectrum, and algorithms motivated by study of chaotic dynamics. We discuss further mathematical properties of ApEn, including the choice of input parameters, statistical issues, and modeling considerations, and we conclude with a section on caveats to ensure correct ApEn utilization.

Human cardiovascular adjustments to exercise and thermal stress.

1974-01-01

L. B. Rowell

Physiological time-series analysis using approximate entropy and sample entropy

2000-06-01

Joshua Richman , J. Randall Moorman

Entropy, as it relates to dynamical systems, is the rate of information production. Methods for estimation of the entropy of a system represented by a time series are not, however, … Entropy, as it relates to dynamical systems, is the rate of information production. Methods for estimation of the entropy of a system represented by a time series are not, however, well suited to analysis of the short and noisy data sets encountered in cardiovascular and other biological studies. Pincus introduced approximate entropy (ApEn), a set of measures of system complexity closely related to entropy, which is easily applied to clinical cardiovascular and other time series. ApEn statistics, however, lead to inconsistent results. We have developed a new and related complexity measure, sample entropy (SampEn), and have compared ApEn and SampEn by using them to analyze sets of random numbers with known probabilistic character. We have also evaluated cross-ApEn and cross-SampEn, which use cardiovascular data sets to measure the similarity of two distinct time series. SampEn agreed with theory much more closely than ApEn over a broad range of conditions. The improved accuracy of SampEn statistics should make them useful in the study of experimental clinical cardiovascular and other biological time series.

Somatosensory, proprioceptive, and sympathetic activity in human peripheral nerves

1979-10-01

Å. B. Vallbo , K E Hagbarth , H. E. Torebjörk +1 more

The sympathetic control of blood pressure

2006-05-01

Patrice G. Guyenet

Decreased heart rate variability and its association with increased mortality after acute myocardial infarction

1987-02-01

Robert E. Kleiger , J. Philip Miller , J. Thomas Bigger +1 more

Kubios HRV – Heart rate variability analysis software

2013-08-06

Mika P. Tarvainen , Juha‐Pekka Niskanen , Jukka A. Lipponen +2 more

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Impact of Depression and Antidepressant Treatment on Heart Rate Variability: A Review and Meta-Analysis

2010-02-09

Andrew H. Kemp , Daniel Quintana , Marcus A. Gray +3 more

Heart Rate Variability, Prefrontal Neural Function, and Cognitive Performance: The Neurovisceral Integration Perspective on Self-regulation, Adaptation, and Health

2009-04-01

Julian F. Thayer , Anita L. Hansen , Evelyn Saus-Rose +1 more

In the present paper, we describe a model of neurovisceral integration in which a set of neural structures involved in cognitive, affective, and autonomic regulation are related to heart rate … In the present paper, we describe a model of neurovisceral integration in which a set of neural structures involved in cognitive, affective, and autonomic regulation are related to heart rate variability (HRV) and cognitive performance.We detail the pathways involved in the neural regulation of the cardiovascular system and provide pharmacological and neuroimaging data in support of the neural structures linking the central nervous system to HRV in humans. We review a number of studies from our group showing that individual differences in HRV are related to performance on tasks associated with executive function and prefrontal cortical activity. These studies include comparisons of executive- and nonexecutive-function tasks in healthy participants, in both threatening and nonthreatening conditions. In addition, we show that manipulating resting HRV levels is associated with changes in performance on executive-function tasks. We also examine the relationship between HRV and cognitive performance in ecologically valid situations using a police shooting simulation and a naval navigation simulation. Finally, we review our studies in anxiety patients, as well as studies examining psychopathy.These findings in total suggest an important relationship among cognitive performance, HRV, and prefrontal neural function that has important implications for both physical and mental health. Future studies are needed to determine exactly which executive functions are associated with individual differences in HRV in a wider range of situations and populations.

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Circadian blood pressure changes and left ventricular hypertrophy in essential hypertension.

1990-02-01

Paolo Verdecchia , Giuseppe Schillaci , M Guerrieri +4 more

The effects of circadian blood pressure (BP) changes on the echocardiographic parameters of left ventricular (LV) hypertrophy were investigated in 235 consecutive subjects (137 unselected untreated patients with essential hypertension … The effects of circadian blood pressure (BP) changes on the echocardiographic parameters of left ventricular (LV) hypertrophy were investigated in 235 consecutive subjects (137 unselected untreated patients with essential hypertension and 98 healthy normotensive subjects) who underwent 24-hour noninvasive ambulatory blood pressure monitoring (ABPM) and cross-sectional and M-mode echocardiography. In the hypertensive group, LV mass index correlated with nighttime (8:00 PM to 6:00 AM) systolic (r = 0.51) and diastolic (r = 0.35) blood pressure more closely than with daytime (6:00 AM to 8:00 PM) systolic (r = 0.38) and diastolic (r = 0.20) BP, or with casual systolic (r = 0.33) and diastolic (r = 0.27) BP. Hypertensive patients were divided into two groups by presence (group 1) and absence (group 2) of a reduction of both systolic and diastolic BP during the night by an average of more than 10% of the daytime pressure. Casual BP, ambulatory daytime systolic and diastolic BP, sex, body surface area, duration of hypertension, prevalence of diabetes, quantity of sleep during monitoring, funduscopic changes, and serum creatinine did not differ between the two groups. LV mass index, after adjustment for the age, the sex, the height, and the daytime BP differences between the two groups (analysis of covariance) was 82.4 g/m2 in the normotensive patient group, 83.5 g/m2 in hypertensive patients of group 1 and 98.3 g/m2 in hypertensive patients of group 2 (normotensive patients vs. group 1, p = NS; group 1 vs. group 2, p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

The Value of Cardiovascular Autonomic Function Tests: 10 Years Experience in Diabetes

1985-09-01

D J Ewing , Christopher Martyn , Robert J. Young +1 more

Five simple, noninvasive cardiovascular reflex tests have been used to assess autonomic function in one center over the past 10 yr. Seven hundred seventy-four diabetic subjects were tested for diagnostic … Five simple, noninvasive cardiovascular reflex tests have been used to assess autonomic function in one center over the past 10 yr. Seven hundred seventy-four diabetic subjects were tested for diagnostic and research purposes. In 543 subjects completing all five tests, abnormalities of heart rate tests occurred in 40%, while abnormal blood pressure tests occurred in less than 20%. Their results were grouped as normal (39%), early (15%), definite (18%), and severe (22%) involvement. Six percent had an atypical pattern of results. Two hundred thirty-seven diabetic subjects had the tests repeated greater than or equal to 3 mo apart: 26% worsened, 71% were unchanged, and only 3% improved. The worsening followed a sequential pattern with first heart rate and later additional blood pressure abnormalities. Comparison between a single test (heart rate response to deep breathing) and the full battery in 360 subjects showed that one test alone does not distinguish the degree or severity of autonomic damage. These tests provide a useful framework to assess autonomic neuropathy simply, quickly, and noninvasively.

Heart rate variability: a review

2006-11-16

U. Rajendra Acharya , K. Paul Joseph , N. Kannathal +2 more

Prospective Study of Heart Rate Variability and Mortality in Chronic Heart Failure

1998-10-13

James Nolan , Phillip D Batin , Richard Andrews +7 more

Background —Patients with chronic heart failure (CHF) have a continuing high mortality. Autonomic dysfunction may play an important role in the pathophysiology of cardiac death in CHF. UK-HEART examined the … Background —Patients with chronic heart failure (CHF) have a continuing high mortality. Autonomic dysfunction may play an important role in the pathophysiology of cardiac death in CHF. UK-HEART examined the value of heart rate variability (HRV) measures as independent predictors of death in CHF. Methods and Results —In a prospective study powered for mortality, we recruited 433 outpatients 62±9.6 years old with CHF (NYHA functional class I to III; mean ejection fraction, 0.41±0.17). Time-domain HRV indices and conventional prognostic indicators were related to death by multivariate analysis. During 482±161 days of follow-up, cardiothoracic ratio, SDNN, left ventricular end-systolic diameter, and serum sodium were significant predictors of all-cause mortality. The risk ratio for a 41.2-ms decrease in SDNN was 1.62 (95% CI, 1.16 to 2.44). The annual mortality rate for the study population in SDNN subgroups was 5.5% for >100 ms, 12.7% for 50 to 100 ms, and 51.4% for <50 ms. SDNN, creatinine, and serum sodium were related to progressive heart failure death. Cardiothoracic ratio, left ventricular end-diastolic diameter, the presence of nonsustained ventricular tachycardia, and serum potassium were related to sudden cardiac death. A reduction in SDNN was the most powerful predictor of the risk of death due to progressive heart failure. Conclusions —CHF is associated with autonomic dysfunction, which can be quantified by measuring HRV. A reduction in SDNN identifies patients at high risk of death and is a better predictor of death due to progressive heart failure than other conventional clinical measurements. High-risk subgroups identified by this measurement are candidates for additional therapy after prescription of an ACE inhibitor.

Autonomic nervous system activity in emotion: A review

2010-04-05

Sylvia D. Kreibig

Impact of Reduced Heart Rate Variability on Risk for Cardiac Events

1996-12-01

Hisako Tsuji , Martin G. Larson , Ferdinand J. Venditti +4 more

Although heart rate variability (HRV) is altered in a variety of pathological conditions, the association of reduced HRV with risk for new cardiac events has not been studied in a … Although heart rate variability (HRV) is altered in a variety of pathological conditions, the association of reduced HRV with risk for new cardiac events has not been studied in a large community-based population.The first 2 hours of ambulatory ECG recordings obtained on subjects of the Framingham Heart Study who were free of clinically apparent coronary heart disease or congestive heart failure were reprocessed to assess HRV. Five frequency-domain measures and three time-domain measures were obtained. The associations between HRV measures and the incidence of new cardiac events (angina pectroris, myocardial infarction, coronary heart disease death, or congestive heart failure) were assessed with proportional hazards regression analyses. There were 2501 eligible subjects with a mean age of 53 years. During a mean follow-up of 3.5 years, cardiac events occurred in 58 subjects. After adjustment for age, sex, cigarette smoking, diabetes, left ventricular hypertrophy, and other relevant risk factors, all HRV measures except the ratio of low-frequency to high-frequency power were significantly associated with risk for a cardiac event (P = .0016 to .0496). A one-standard deviation decrement in the standard deviation of total normal RR intervals (natural log transformed) was associated with a hazard ratio of 1.47 for new cardiac events (95% confidence interval of 1.16 to 1.86).The estimation of HRV by ambulatory monitoring offers prognostic information beyond that provided by the evaluation of traditional cardiovascular disease risk factors.

Heart Rate Variability as an Index of Regulated Emotional Responding

2006-09-01

Bradley M. Appelhans , Linda J. Luecken

The study of individual differences in emotional responding can provide considerable insight into interpersonal dynamics and the etiology of psychopathology. Heart rate variability (HRV) analysis is emerging as an objective … The study of individual differences in emotional responding can provide considerable insight into interpersonal dynamics and the etiology of psychopathology. Heart rate variability (HRV) analysis is emerging as an objective measure of regulated emotional responding (generating emotional responses of appropriate timing and magnitude). This review provides a theoretical and empirical rationale for the use of HRV as an index of individual differences in regulated emotional responding. Two major theoretical frameworks that articulate the role of HRV in emotional responding are presented, and relevant empirical literature is reviewed. The case is made that HRV is an accessible research tool that can increase the understanding of emotion in social and psychopathological processes.

Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympatho-vagal interaction in man and conscious dog.

1986-08-01

M. Pagani , Federico Lombardi , Stefano Guzzetti +7 more

In 57 normal subjects (age 20-60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90 degrees upright tilt, controlled respiration (n = 16) and … In 57 normal subjects (age 20-60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90 degrees upright tilt, controlled respiration (n = 16) and acute (n = 10) and chronic (n = 12) beta-adrenergic receptor blockade. Automatic computer analysis provided the autoregressive power spectral density, as well as the number and relative power of the individual components. The power spectral density of R-R interval variability contained two major components in power, a high frequency at approximately 0.25 Hz and a low frequency at approximately 0.1 Hz, with a normalized low frequency:high frequency ratio of 3.6 +/- 0.7. With tilt, the low-frequency component became largely predominant (90 +/- 1%) with a low frequency:high frequency ratio of 21 +/- 4. Acute beta-adrenergic receptor blockade (0.2 mg/kg IV propranolol) increased variance at rest and markedly blunted the increase in low frequency and low frequency:high frequency ratio induced by tilt. Chronic beta-adrenergic receptor blockade (0.6 mg/kg p.o. propranolol, t.i.d.), in addition, reduced low frequency and increased high frequency at rest, while limiting the low frequency:high frequency ratio increase produced by tilt. Controlled respiration produced at rest a marked increase in the high-frequency component, with a reduction of the low-frequency component and of the low frequency:high frequency ratio (0.7 +/- 0.1); during tilt, the increase in the low frequency:high frequency ratio (8.3 +/- 1.6) was significantly smaller. In seven additional subjects in whom direct high-fidelity arterial pressure was recorded, simultaneous R-R interval and arterial pressure variabilities were examined at rest and during tilt. Also, the power spectral density of arterial pressure variability contained two major components, with a relative low frequency:high frequency ratio at rest of 2.8 +/- 0.7, which became 17 +/- 5 with tilt. These power spectral density components were numerically similar to those observed in R-R variability. Thus, invasive and noninvasive studies provided similar results. More direct information on the role of cardiac sympathetic nerves on R-R and arterial pressure variabilities was derived from a group of experiments in conscious dogs before and after bilateral stellectomy. Under control conditions, high frequency was predominant and low frequency was very small or absent, owing to a predominant vagal tone. During a 9% decrease in arterial pressure obtained with IV nitroglycerin, there was a marked increase in low frequency, as a result of reflex sympathetic activation.(ABSTRACT TRUNCATED AT 400 WORDS)

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Frequency domain measures of heart period variability and mortality after myocardial infarction.

1992-01-01

J. Thomas Bigger , Joseph L. Fleiss , R.C. Steinman +3 more

BACKGROUND We studied 715 patients 2 weeks after myocardial infarction to establish the associations between six frequency domain measures of heart period variability (HPV) and mortality during 4 years of … BACKGROUND We studied 715 patients 2 weeks after myocardial infarction to establish the associations between six frequency domain measures of heart period variability (HPV) and mortality during 4 years of follow-up. METHODS AND RESULTS Each measure of HPV had a significant and at least moderately strong univariate association with all-cause mortality, cardiac death, and arrhythmic death. Power in the lower-frequency bands--ultra low frequency (ULF) and very low frequency (VLF) power--had stronger associations with all three mortality end points than power in the higher-frequency bands--low frequency (LF) and high frequency (HF) power. The 24-hour total power also had a significant and strong association with all three mortality end points. VLF power was the only variable that was more strongly associated with arrhythmic death than with cardiac death or all-cause mortality. In multivariate Cox regression models using a step-up approach to evaluate the independent associations between frequency domain measures of heart period variability and death of all causes, ULF power was selected first (i.e., was the single component with the strongest association). Adding VLF or LF power to the Cox regression model significantly improved the prediction of outcome. With both ULF and VLF power in the Cox regression model, the addition of the other two components, LF and HF power, singly or together, did not significantly improve the prediction of all-cause mortality. We explored the relation between the heart period variability measures and all-cause mortality, cardiac death, and arrhythmic death before and after adjusting for five previously established postinfarction risk predictors: age, New York Heart Association functional class, rales in the coronary care unit, left ventricular ejection fraction, and ventricular arrhythmias detected in a 24-hour Holter ECG recording. CONCLUSIONS After adjustment for the five risk predictors, the association between mortality and total, ULF, and VLF power remained significant and strong, whereas LF and HF power were only moderately strongly associated with mortality. The tendency for VLF power to be more strongly associated with arrhythmic death than with all-cause or cardiac death was still evident after adjusting for the five covariates. Adding measures of HPV to previously known predictors of risk after myocardial infarction identifies small subgroups with a 2.5-year mortality risk of approximately 50%.

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Heart Rate Variability: Measurement and Clinical Utility

2005-01-01

Robert E. Kleiger , Phyllis K. Stein , J. Thomas Bigger

Electrocardiographic RR intervals fluctuate cyclically, modulated by ventilation, baroreflexes, and other genetic and environmental factors that are mediated through the autonomic nervous system. Short term electrocardiographic recordings (5 to 15 … Electrocardiographic RR intervals fluctuate cyclically, modulated by ventilation, baroreflexes, and other genetic and environmental factors that are mediated through the autonomic nervous system. Short term electrocardiographic recordings (5 to 15 minutes), made under controlled conditions, e.g., lying supine or standing or tilted upright can elucidate physiologic, pharmacologic, or pathologic changes in autonomic nervous system function. Long‐term, usually 24‐hour recordings, can be used to assess autonomic nervous responses during normal daily activities in health, disease, and in response to therapeutic interventions, e.g., exercise or drugs. RR interval variability is useful for assessing risk of cardiovascular death or arrhythmic events, especially when combined with other tests, e.g., left ventricular ejection fraction or ventricular arrhythmias.

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Multiscale Entropy Analysis of Complex Physiologic Time Series

2002-07-19

Madalena D. Costa , Ary L. Goldberger , Chung‐Kang Peng

There has been considerable interest in quantifying the complexity of physiologic time series, such as heart rate. However, traditional algorithms indicate higher complexity for certain pathologic processes associated with random … There has been considerable interest in quantifying the complexity of physiologic time series, such as heart rate. However, traditional algorithms indicate higher complexity for certain pathologic processes associated with random outputs than for healthy dynamics exhibiting long-range correlations. This paradox may be due to the fact that conventional algorithms fail to account for the multiple time scales inherent in healthy physiologic dynamics. We introduce a method to calculate multiscale entropy (MSE) for complex time series. We find that MSE robustly separates healthy and pathologic groups and consistently yields higher values for simulated long-range correlated noise compared to uncorrelated noise.

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Claude Bernard and the heart–brain connection: Further elaboration of a model of neurovisceral integration

2008-08-14

Julian F. Thayer , Richard D. Lane

Heart rate variability: Origins, methods, and interpretive caveats

1997-11-01

Gary G. Berntson , J. Thomas Bigger , Dwain L. Eckberg +7 more

Abstract Components of heart rate variability have attracted considerable attention in psychology and medicine and have become important dependent measures in psychophysiology and behavioral medicine. Quantification and interpretation of heart … Abstract Components of heart rate variability have attracted considerable attention in psychology and medicine and have become important dependent measures in psychophysiology and behavioral medicine. Quantification and interpretation of heart rate variability, however, remain complex issues and are fraught with pitfalls. The present report (a) examines the physiological origins and mechanisms of heart rate variability, (b) considers quantitative approaches to measurement, and (c) highlights important caveats in the interpretation of heart rate variability. Summary guidelines for research in this area are outlined, and suggestions and prospects for future developments are considered.

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Loss of 'Complexity' and Aging

1992-04-01

Lewis A. Lipsitz

The concept of "complexity," derived from the field of nonlinear dynamics, can be adapted to measure the output of physiologic processes that generate highly variable fluctuations resembling "chaos." We review … The concept of "complexity," derived from the field of nonlinear dynamics, can be adapted to measure the output of physiologic processes that generate highly variable fluctuations resembling "chaos." We review data suggesting that physiologic aging is associated with a generalized loss of such complexity in the dynamics of healthy organ system function and hypothesize that such loss of complexity leads to an impaired ability to adapt to physiologic stress. This hypothesis is supported by observations showing an age-related loss of complex variability in multiple physiologic processes including cardiovascular control, pulsatile hormone release, and electroencephalographic potentials. If further research supports this hypothesis, measures of complexity based on chaos theory and the related geometric concept of fractals may provide new ways to monitor senescence and test the efficacy of specific interventions to modify the age-related decline in adaptive capacity.

Human cingulate cortex and autonomic control: converging neuroimaging and clinical evidence

2003-09-05

Hugo Critchley , Christopher J. Mathias , Oliver Josephs +6 more

Human anterior cingulate function has been explained primarily within a cognitive framework. We used functional MRI experiments with simultaneous electrocardiography to examine regional brain activity associated with autonomic cardiovascular control … Human anterior cingulate function has been explained primarily within a cognitive framework. We used functional MRI experiments with simultaneous electrocardiography to examine regional brain activity associated with autonomic cardiovascular control during performance of cognitive and motor tasks. Using indices of heart rate variability, and high- and low-frequency power in the cardiac rhythm, we observed activity in the dorsal anterior cingulate cortex (ACC) related to sympathetic modulation of heart rate that was dissociable from cognitive and motor-related activity. The findings predict that during effortful cognitive and motor behaviour the dorsal ACC supports the generation of associated autonomic states of cardiovascular arousal. We subsequently tested this prediction by studying three patients with focal damage involving the ACC while they performed effortful cognitive and motor tests. Each showed abnormalities in autonomic cardiovascular responses with blunted autonomic arousal to mental stress when compared with 147 normal subjects tested in identical fashion. Thus, converging neuroimaging and clinical findings suggest that ACC function mediates context-driven modulation of bodily arousal states.

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Diabetic Cardiovascular Autonomic Neuropathy

2007-01-23

Aaron I. Vinik , Dan Ziegler

O ne of the most overlooked of all serious complications of diabetes is cardiovascular autonomic neuropathy (CAN), [1][2][3] which encompasses damage to the autonomic nerve fibers that innervate the heart … O ne of the most overlooked of all serious complications of diabetes is cardiovascular autonomic neuropathy (CAN), [1][2][3] which encompasses damage to the autonomic nerve fibers that innervate the heart and blood vessels, resulting in abnormalities in heart rate control and vascular dynamics. 4he present report discusses the clinical manifestations (eg, resting tachycardia, orthostasis, exercise intolerance, intraoperative cardiovascular liability, silent myocardial infarction [MI], and increased risk of mortality) in the presence of CAN.It also demonstrates that autonomic dysfunction can affect daily activities of individuals with diabetes and may invoke potentially life-threatening outcomes.Advances in technology, built on decades of research and clinical testing, now make it possible to objectively identify early stages of CAN with the use of careful measurement of autonomic function and to provide therapeutic choices that are based on symptom control and that might abrogate the underlying disorder. Epidemiology of CANLittle information exists as to frequency of CAN in representative diabetic populations.This is further complicated by the differences in the methodology used and the lack of standardization.Fifteen studies using different end points report prevalence rates of 1% to 90%. 1 The heterogenous methodology makes it difficult to compare epidemiology across different studies.CAN may be present at diagnosis, and prevalence increases with age, duration of diabetes, and poor glycemic control.CAN also cosegregates with distal symmetric polyneuropathy, microangiopathy, and macroangiopathy.Age, diabetes, obesity, and smoking are risk factors for reduced heart rate variability (HRV) 5 in type 2 diabetes.Thus, there may be selectivity and sex-related differences among the various cardiovascular risk factors as to their influence on autonomic dysfunction. 6HbA1c, hypertension, distal symmetrical polyneuropathy, retinopathy, and exposure to hyperglycemia were shown to be risk factors for developing CAN in type 1 diabetes. 7 Clinical Manifestations of CAN Resting TachycardiaWhereas abnormalities in HRV are early findings of CAN, resting tachycardia and a fixed heart rate are characteristic late findings in diabetic patients with vagal impairment. 8esting heart rates of 90 to 100 bpm and occasional heart rate increments up to 130 bpm occur.The highest resting heart rates have been found in patients with parasympathetic damage, occurring earlier in the course of CAN than sympathetic nerve function; in those with evidence for combined vagal and sympathetic involvement, the rate returns toward normal but remains elevated.A fixed heart rate that is unresponsive to moderate exercise, stress, or sleep indicates almost complete cardiac denervation. 8Thus, heart rate may not provide a reliable diagnostic criterion of CAN in the absence of other causes unless it is increased by more than 100 bpm.

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The LF/HF ratio does not accurately measure cardiac sympatho-vagal balance

2013-01-01

George E. Billman

OPINION article Front. Physiol., 20 February 2013Sec. Clinical and Translational Physiology Volume 4 - 2013 | https://doi.org/10.3389/fphys.2013.00026 OPINION article Front. Physiol., 20 February 2013Sec. Clinical and Translational Physiology Volume 4 - 2013 | https://doi.org/10.3389/fphys.2013.00026

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Effect of Insulin and Glucose Infusions on Sympathetic Nervous System Activity in Normal Man

1981-03-01

John W. Rowe , James B. Young , Kenneth L. Minaker +3 more

Recent studies indicate a link between carbohydrate intake and the functional state of the sympathetic nervous system. Fasting or carbohydrate restriction decreases sympathetic activity, while glucose ingestion or dietary supplementation … Recent studies indicate a link between carbohydrate intake and the functional state of the sympathetic nervous system. Fasting or carbohydrate restriction decreases sympathetic activity, while glucose ingestion or dietary supplementation with sucrose increases sympathetic nerve activity. To examine the potential contributions of hyperglycemia and hyperinsulinemia to sympathetic stimulation, sympathetic activity was assessed by measurement of plasma norepinephrine (NE) levels and concomitant cardiovascular indices in nonobese young men during glucose and insulin infusions using glucose clamp techniques. In the insulin infusion studies (euglycemic glucose clamp), insulin was administered at 2 mU/kg/min and 5 mU/kg/min for 2 h while blood glucose was maintained at basal levels by a variable rate of glucose infusion. In the hyperglycemic studies, blood glucose was raised 125 mg/dl above basal and maintained at that level for 2h. In response to both insulin infusions, plasma NE rose progressively over the course of the study, increasing 50% with the 2-mU infusion (from mean basal value of 240 ± 34 pg/ml to 360 ± 41 at 150 min, P &lt; 0.001 for changes over time by analysis of variance) and 117% with the 5-mil infusion (from 254 ± 20 pg/ml to 551 ± 88 at 150 min, P &lt; 0.001). The plasma NE response was greater with the 5-mll than with the 2-mU insulin infusion (P &lt; 0.001), and similarly, was greater during the 2-mU insulin infusion than during a control test in which neither insulin nor glucose was infused (P &lt; 0.001). Associated with the elevations in plasma NE In the 2-mU insulin infusion were increases in pulse rate (P &lt; 0.05), pulse pressure (P &lt; 0.005), and pulse rate - systolic blood pressure product (P &lt; 0.01), and during the 5-mU insulin infusions there were increases in pulse pressure (P &lt; 0.001), mean arterial blood pressure (P &lt; 0.001), and pulse rate - systolic blood pressure product (P &lt; 0.001). Plasma NE did not change during the hyperglycemic glucose clamp nor during control tests, and pulse pressure in the hyperglycemic studies (P &lt; 0.005) was the only cardiovascular measurement increased by these two infusion protocols. The clearance of NE in three subjects was unaffected by the 2-mU insulin infusion. Thus, insulin infusion increases sympathetic nervous system activity in the absence of changes in blood glucose.

Power Spectrum Analysis of Heart Rate Fluctuation: A Quantitative Probe of Beat-to-Beat Cardiovascular Control

1981-07-10

S. Akselrod , David Gordon , F. Andrew Ubel +3 more

Power spectrum analysis of heart rate fluctuations provides a quantitative noninvasive means of assessing the functioning of the short-term cardiovascular control systems. We show that sympathetic and parasympathetic nervous activity … Power spectrum analysis of heart rate fluctuations provides a quantitative noninvasive means of assessing the functioning of the short-term cardiovascular control systems. We show that sympathetic and parasympathetic nervous activity make frequency-specific contributions to the heart rate power spectrum, and that renin-angiotensin system activity strongly modulates the amplitude of the spectral peak located at 0.04 hertz. Our data therefore provide evidence that the renin-angiotensin system plays a significant role in short-term cardiovascular control on the time scale of seconds to minutes.

Sample entropy analysis of neonatal heart rate variability

2002-09-01

Douglas E. Lake , Joshua Richman , M. Pamela Griffin +1 more

Abnormal heart rate characteristics of reduced variability and transient decelerations are present early in the course of neonatal sepsis. To investigate the dynamics, we calculated sample entropy, a similar but … Abnormal heart rate characteristics of reduced variability and transient decelerations are present early in the course of neonatal sepsis. To investigate the dynamics, we calculated sample entropy, a similar but less biased measure than the popular approximate entropy. Both calculate the probability that epochs of window length m that are similar within a tolerance r remain similar at the next point. We studied 89 consecutive admissions to a tertiary care neonatal intensive care unit, among whom there were 21 episodes of sepsis, and we performed numerical simulations. We addressed the fundamental issues of optimal selection of m and r and the impact of missing data. The major findings are that entropy falls before clinical signs of neonatal sepsis and that missing points are well tolerated. The major mechanism, surprisingly, is unrelated to the regularity of the data: entropy estimates inevitably fall in any record with spikes. We propose more informed selection of parameters and reexamination of studies where approximate entropy was interpreted solely as a regularity measure.

A healthy heart is not a metronome: an integrative review of the heart's anatomy and heart rate variability

2014-09-30

Fred Shaffer , Rollin McCraty , C Zerr

Heart rate variability (HRV), the change in the time intervals between adjacent heartbeats, is an emergent property of interdependent regulatory systems that operate on different time scales to adapt to … Heart rate variability (HRV), the change in the time intervals between adjacent heartbeats, is an emergent property of interdependent regulatory systems that operate on different time scales to adapt to challenges and achieve optimal performance. This article briefly reviews neural regulation of the heart, and its basic anatomy, the cardiac cycle, and the sinoatrial and atrioventricular pacemakers. The cardiovascular regulation center in the medulla integrates sensory information and input from higher brain centers, and afferent cardiovascular system inputs to adjust heart rate and blood pressure via sympathetic and parasympathetic efferent pathways. This article reviews sympathetic and parasympathetic influences on the heart, and examines the interpretation of HRV and the association between reduced HRV, risk of disease and mortality, and the loss of regulatory capacity. This article also discusses the intrinsic cardiac nervous system and the heart-brain connection, through which afferent information can influence activity in the subcortical and frontocortical areas, and motor cortex. It also considers new perspectives on the putative underlying physiological mechanisms and properties of the ultra-low-frequency (ULF), very-low-frequency (VLF), low-frequency (LF), and high-frequency (HF) bands. Additionally, it reviews the most common time and frequency domain measurements as well as standardized data collection protocols. In its final section, this article integrates Porges' polyvagal theory, Thayer and colleagues' neurovisceral integration model, Lehrer, Vaschillo, and Vaschillo's resonance frequency model, and the Institute of HeartMath's coherence model. The authors conclude that a coherent heart is not a metronome because its rhythms are characterized by both complexity and stability over longer time scales. Future research should expand understanding of how the heart and its intrinsic nervous system influence the brain.

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Cardiovascular neural regulation explored in the frequency domain.

1991-08-01

Alberto Malliani , M. Pagani , Federico Lombardi +1 more

A consistent link appears to exist between predominance of vagal or sympathetic activity and predominance of HF or LF oscillations, respectively: RR variability contains both of these rhythms, and their … A consistent link appears to exist between predominance of vagal or sympathetic activity and predominance of HF or LF oscillations, respectively: RR variability contains both of these rhythms, and their relative powers appear to subserve a reciprocal relation like that commonly found in sympathovagal balance. In this respect, it is our opinion that rhythms and neural components always interact, just like flexor and extensor tones or excitatory and inhibitory cardiovascular reflexes, and that it is misleading to separately consider vagal and sympathetic modulations of heart rate. In humans and experimental animals, functional states likely to be accompanied by an increased sympathetic activity are characterized by a shift of the LF-HF balance in favor of the LF component; the opposite occurs during presumed increases in vagal activity. In addition, LF oscillation evaluated from SAP variability appears to be a convenient marker of the sympathetic modulation of vasomotor activity. Although based on indirect markers, the exploration in the frequency domain of cardiovascular neural regulation might disclose a unitary vision hard to reach through the assemblage of more specific but fragmented pieces of information.

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A meta-analysis of heart rate variability and neuroimaging studies: Implications for heart rate variability as a marker of stress and health

2011-12-11

Julian F. Thayer , Fredrik Åhs , Mats Fredrikson +2 more

Heart rate variability: Standards of measurement, physiological interpretation, and clinical use

1996-03-01

Marek Malik , J. Thomas Bigger , A. John Camm +4 more

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The relationship of autonomic imbalance, heart rate variability and cardiovascular disease risk factors

2009-11-13

Julian F. Thayer , Shelby Yamamoto , J. F. Brosschot

Reflex Regulation of Arterial Pressure during Sleep in Man

1969-01-01

Harley S. Smyth , Peter Sleight , George Pickering

The control of arterial pressure during sleep was studied in 13 untreated, unsedated subjects aged 20 to 46, including 7 with hypertension. Arterial pressure was measured directly. A transient rise … The control of arterial pressure during sleep was studied in 13 untreated, unsedated subjects aged 20 to 46, including 7 with hypertension. Arterial pressure was measured directly. A transient rise of arterial pressure up to 30 mm Hg was produced by the sudden intravenous injection of 0.25 to 2 µg of angiotensin. Linear plots were obtained in 10 of 13 subjects when the systolic pressures of successive pulses during the pressure rise were plotted against the pulse intervals which began the next beat. The relationship was disturbed by movement or arousal, and was better when pulse intervals falling in inspiration were discarded. The slope of the line (milliseconds of cardiac slowing per millimeter rise in systolic pressure) in the awake subject ranged from 2 to 15.5 msec/mm Hg, and from 4.5 to 28.9 during sleep. Reflex sensitivity was highest in dreaming sleep. In 7 of 10 subjects, baroreflex sensitivity increased significantly during sleep; in 6, the prevailing arterial pressure was inversely correlated with the baroreflex sensitivity. The pressure appeared to be the dependent variable. It is concluded that the baroreceptor reflex are can be rapidly reset, particularly during sleep. The lower arterial pressures during sleep may be actively maintained in some subjects by increased baroreflex sensitivity.

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Diabetic Autonomic Neuropathy

2003-05-01

Aaron I. Vinik , Raelene E. Maser , Braxton D. Mitchell +1 more

Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes. Despite its relationship to an increased risk of cardiovascular mortality and its association with multiple symptoms and impairments, … Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes. Despite its relationship to an increased risk of cardiovascular mortality and its association with multiple symptoms and impairments, the significance of DAN has not been fully appreciated. The reported prevalence of DAN varies widely depending on the cohort studied and the methods of assessment. In randomly selected cohorts of asymptomatic individuals with diabetes, ∼20% had abnormal cardiovascular autonomic function. DAN frequently coexists with other peripheral neuropathies and other diabetic complications, but DAN may be isolated, frequently preceding the detection of other complications. Major clinical manifestations of DAN include resting tachycardia, exercise intolerance, orthostatic hypotension, constipation, gastroparesis, erectile dysfunction, sudomotor dysfunction, impaired neurovascular function, “brittle diabetes,” and hypoglycemic autonomic failure. DAN may affect many organ systems throughout the body (e.g., gastrointestinal [GI], genitourinary, and cardiovascular). GI disturbances (e.g., esophageal enteropathy, gastroparesis, constipation, diarrhea, and fecal incontinence) are common, and any section of the GI tract may be affected. Gastroparesis should be suspected in individuals with erratic glucose control. Upper-GI symptoms should lead to consideration of all possible causes, including autonomic dysfunction. Whereas a radiographic gastric emptying study can definitively establish the diagnosis of gastroparesis, a reasonable approach is to exclude autonomic dysfunction and other known causes of these upper-GI symptoms. Constipation is the most common lower-GI symptom but can alternate with episodes of diarrhea. Diagnostic approaches should rule out autonomic dysfunction and the well-known causes such as neoplasia. Occasionally, anorectal manometry and other specialized tests typically performed by the gastroenterologist may be helpful. DAN is also associated with genitourinary tract disturbances including bladder and/or sexual dysfunction. Evaluation of bladder dysfunction should be performed for individuals with diabetes who have recurrent urinary tract infections, pyelonephritis, incontinence, or a palpable bladder. Specialized assessment of bladder dysfunction will typically be performed by a urologist. In men, DAN may cause loss of penile erection and/or retrograde ejaculation. A complete workup for erectile dysfunction in men should include history (medical and sexual); psychological evaluation; hormone levels; measurement of nocturnal penile tumescence; tests to assess penile, pelvic, and spinal nerve function; cardiovascular autonomic function tests; and measurement of penile and brachial blood pressure. Neurovascular dysfunction resulting from DAN contributes to a wide spectrum of clinical disorders including erectile dysfunction, loss of skin integrity, and abnormal vascular reflexes. Disruption of microvascular skin blood flow and sudomotor function may be among the earliest manifestations of DAN and lead to dry skin, loss of sweating, and the development of fissures and cracks that allow microorganisms to enter. These changes ultimately contribute to the development of ulcers, gangrene, and limb loss. Various aspects of neurovascular function can be evaluated with specialized tests, but generally these have not been well standardized and have limited clinical utility. Cardiovascular autonomic neuropathy (CAN) is the most studied and clinically important form of DAN. Meta-analyses of published data demonstrate that reduced cardiovascular autonomic function as measured by heart rate variability (HRV) is strongly (i.e., relative risk is doubled) associated with an increased risk of silent myocardial ischemia and mortality. The determination of the presence of CAN is usually based on a battery of autonomic function tests rather than just on one test. Proceedings from a consensus conference in 1992 recommended that three tests (R-R variation, Valsalva maneuver, and postural blood pressure testing) be used for longitudinal testing of the cardiovascular autonomic system. Other forms of autonomic neuropathy can be evaluated with specialized tests, but these are less standardized and less available than commonly used tests of cardiovascular autonomic function, which quantify loss of HRV. Interpretability of serial HRV testing requires accurate, precise, and reproducible procedures that use established physiological maneuvers. The battery of three recommended tests for assessing CAN is readily performed in the average clinic, hospital, or diagnostic center with the use of available technology. Measurement of HRV at the time of diagnosis of type 2 diabetes and within 5 years after diagnosis of type 1 diabetes (unless an individual has symptoms suggestive of autonomic dysfunction earlier) serves to establish a baseline, with which 1-year interval tests can be compared. Regular HRV testing provides early detection and thereby promotes timely diagnostic and therapeutic interventions. HRV testing may also facilitate differential diagnosis and the attribution of symptoms (e.g., erectile dysfunction, dyspepsia, and dizziness) to autonomic dysfunction. Finally, knowledge of early autonomic dysfunction can encourage patient and physician to improve metabolic control and to use therapies such as ACE inhibitors and β-blockers, proven to be effective for patients with CAN.

Baroreflex sensitivity and heart-rate variability in prediction of total cardiac mortality after myocardial infarction

1998-02-01

Maria Teresa La Rovere , J. Thomas Bigger , Gregory M. Marcus +2 more

Experimental evidence suggests that autonomic markers such as heart-rate variability and baroreflex sensitivity (BRS) may contribute to postinfarction risk stratification. There are clinical data to support this concept for heart-rate … Experimental evidence suggests that autonomic markers such as heart-rate variability and baroreflex sensitivity (BRS) may contribute to postinfarction risk stratification. There are clinical data to support this concept for heart-rate variability. The main objective of the ATRAMI study was to provide prospective data on the additional and independent prognostic value for cardiac mortality of heart-rate variability and BRS in patients after myocardial infarction in whom left-ventricular ejection fraction (LVEF) and ventricular arrhythmias were known.This multicentre international prospective study enrolled 1284 patients with a recent (<28 days) myocardial infarction. 24 h Holter recording was done to quantify heart-rate variability (measured as standard deviation of normal to normal RR intervals [SDNN]) and ventricular arrhythmias. BRS was calculated from measurement of the rate-pressure response to intravenous phenylephrine.During 21 (SD 8) months of follow-up, the primary endpoint, cardiac mortality, included 44 cardiac deaths and five non-fatal cardiac arrests. Low values of either heart-rate variability (SDNN <70 ms) or BRS (<3.0 ms per mm Hg) carried a significant multivariate risk of cardiac mortality (3.2 [95% CI 1.42-7.36] and 2.8 [1.24-6.16], respectively). The association of low SDNN and BRS further increased risk; the 2-year mortality was 17% when both were below the cut-offs and 2% (p<0.0001) when both were well preserved (SDNN >105 ms, BRS >6.1 ms per mm Hg). The association of low SDNN or BRS with LVEF below 35% carried a relative risk of 6.7 (3.1-14.6) or 8.7 (4.3-17.6), respectively, compared with patients with LVEF above 35% and less compromised SDNN (> or = 70 ms) and BRS (> or = 3 ms per mm Hg).ATRAMI provides clinical evidence that after myocardial infarction the analysis of vagal reflexes has significant prognostic value independently of LVEF and of ventricular arrhythmias and that it significantly adds to the prognostic value of heart-rate variability.

Hemodynamic regulation: investigation by spectral analysis

1985-10-01

S. Akselrod , David Gordon , Jeffrey B. Madwed +3 more

We investigated the hypothesis that beat-to-beat variability in hemodynamic parameters reflects the dynamic interplay between ongoing perturbations to circulatory function and the compensatory response of short-term cardiovascular control systems. Spontaneous … We investigated the hypothesis that beat-to-beat variability in hemodynamic parameters reflects the dynamic interplay between ongoing perturbations to circulatory function and the compensatory response of short-term cardiovascular control systems. Spontaneous fluctuations in heart rate (HR), arterial blood pressure, and respiration were analyzed by spectral analysis in the 0.02- to 1-Hz frequency range. A simple closed-loop model of short-term cardiovascular control was proposed and evaluated in a series of experiments: pharmacological blockades of the parasympathetic, alpha-sympathetic, beta-sympathetic, and renin-angiotensin systems were used to open the principal control loops in order to examine changes in the spectral pattern of the fluctuations. Atrial pacing was used to examine blood pressure variability in the absence of HR variability. We found that respiratory frequency fluctuations in HR are parasympathetically mediated and that blood pressure fluctuations at this frequency result almost entirely from the direct effect of centrally mediated HR fluctuations. The sympathetic nervous system appears to be too sluggish to mediate respiratory frequency variations. Low-frequency (0.02-0.09 Hz) fluctuations in HR are jointly mediated by the parasympathetic and beta-sympathetic systems and appear to compensate for blood pressure fluctuations at this frequency. Low-frequency blood pressure fluctuations are probably due to variability in vasomotor activity which is normally damped by renin-angiotensin system activity. Blockade of the alpha-adrenergic system, however, does not significantly alter low-frequency blood pressure fluctuations.

Assessment of autonomic function in humans by heart rate spectral analysis

1985-01-01

Bruce Pomeranz , Robert J.B. Macaulay , Marie A. Caudill +7 more

Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated … Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.

Vagal tone, development, and Gray's motivational theory: Toward an integrated model of autonomic nervous system functioning in psychopathology

2001-05-16

Theodore P. Beauchaine

In the last decade, cardiac vagal tone has emerged as a psychophysiological marker of many aspects of behavioral functioning in both children and adults. Research efforts during this time have … In the last decade, cardiac vagal tone has emerged as a psychophysiological marker of many aspects of behavioral functioning in both children and adults. Research efforts during this time have produced an extensive list of vagal tone correlates that includes temperamental variables as well as both anxious/internalizing and disruptive/externalizing behaviors. This potentially confusing state of affairs is compounded by developmental shifts in vagal tone–behavior relations that to date have not been elucidated. In this paper, the vagal tone literature is reviewed, and discrepancies, including the lack of specificity of vagal tone as a psychophysiological marker, are clarified. Such clarification requires that we (a) view vagal tone–behavior relations in developmental context, (b) juxtapose vagal tone–behavior relations in typical and atypical samples, and (c) consider the parasympathetic underpinnings of vagal tone as but one component in a broader model of autonomic nervous system functioning. Such a model is provided by combining Gray's motivational theory with Porges's polyvagal theory. Together these models account for behavioral and emotional differences in a diverse range of psychological disorders that are not differentiated by either model alone. Moreover, use of the integrated model offers a theory-driven approach to the study of autonomic nervous system–behavior relations.

Detecting Stress During Real-World Driving Tasks Using Physiological Sensors

2005-06-01

Jennifer Healey , Rosalind W. Picard

This paper presents methods for collecting and analyzing physiological data during real-world driving tasks to determine a driver's relative stress level. Electrocardiogram, electromyogram, skin conductance, and respiration were recorded continuously … This paper presents methods for collecting and analyzing physiological data during real-world driving tasks to determine a driver's relative stress level. Electrocardiogram, electromyogram, skin conductance, and respiration were recorded continuously while drivers followed a set route through open roads in the greater Boston area. Data from 24 drives of at least 50-min duration were collected for analysis. The data were analyzed in two ways. Analysis I used features from 5-min intervals of data during the rest, highway, and city driving conditions to distinguish three levels of driver stress with an accuracy of over 97% across multiple drivers and driving days. Analysis II compared continuous features, calculated at 1-s intervals throughout the entire drive, with a metric of observable stressors created by independent coders from videotapes. The results show that for most drivers studied, skin conductivity and heart rate metrics are most closely correlated with driver stress level. These findings indicate that physiological signals can provide a metric of driver stress in future cars capable of physiological monitoring. Such a metric could be used to help manage noncritical in-vehicle information systems and could also provide a continuous measure of how different road and traffic conditions affect drivers.

Heart Rate Variability

1996-03-01

Task Force of the European Society of Cardiology the North A Electrophysiology

Heart-Rate Recovery Immediately after Exercise as a Predictor of Mortality

1999-10-28

Christopher R. Cole , Eugene H. Blackstone , Fredric J. Pashkow +2 more

The increase in heart rate that accompanies exercise is due in part to a reduction in vagal tone. Recovery of the heart rate immediately after exercise is a function of … The increase in heart rate that accompanies exercise is due in part to a reduction in vagal tone. Recovery of the heart rate immediately after exercise is a function of vagal reactivation. Because a generalized decrease in vagal activity is known to be a risk factor for death, we hypothesized that a delayed fall in the heart rate after exercise might be an important prognostic marker.For six years we followed 2428 consecutive adults (mean [+/-SD] age, 57+/-12 years; 63 percent men) without a history of heart failure or coronary revascularization and without pacemakers. The patients were undergoing symptom-limited exercise testing and single-photon-emission computed tomography with thallium scintigraphy for diagnostic purposes. The value for the recovery of heart rate was defined as the decrease in the heart rate from peak exercise to one minute after the cessation of exercise. An abnormal value for the recovery of heart rate was defined as a reduction of 12 beats per minute or less from the heart rate at peak exercise.There were 213 deaths from all causes. A total of 639 patients (26 percent) had abnormal values for heart-rate recovery. In univariate analyses, a low value for the recovery of heart rate was strongly predictive of death (relative risk, 4.0; 95 percent confidence interval, 3.0 to 5.2; P<0.001). After adjustments were made for age, sex, the use or nonuse of medications, the presence or absence of myocardial perfusion defects on thallium scintigraphy, standard cardiac risk factors, the resting heart rate, the change in heart rate during exercise, and workload achieved, a low value for heart-rate recovery remained predictive of death (adjusted relative risk, 2.0; 95 percent confidence interval, 1.5 to 2.7; P<0.001).A delayed decrease in the heart rate during the first minute after graded exercise, which may be a reflection of decreased vagal activity, is a powerful predictor of overall mortality, independent of workload, the presence or absence of myocardial perfusion defects, and changes in heart rate during exercise.

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Effect of Exercise on Coronary Endothelial Function in Patients with Coronary Artery Disease

2000-02-17

Rainer Hambrecht , Anamaria Wolf , Stephan Gielen +5 more

Studies of the cardioprotective effects of exercise training in patients with coronary artery disease have yielded contradictory results. Exercise training has been associated with improvement in myocardial perfusion even in … Studies of the cardioprotective effects of exercise training in patients with coronary artery disease have yielded contradictory results. Exercise training has been associated with improvement in myocardial perfusion even in patients who have progression of coronary atherosclerosis. We therefore conducted a prospective study of the effect of exercise training on endothelial function in patients with coronary artery disease.

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Recommendations for Blood Pressure Measurement in Humans and Experimental Animals

2005-02-07

Thomas G. Pickering , John E. Hall , Lawrence J. Appel +7 more

Accurate measurement of blood pressure is essential to classify individuals, to ascertain blood pressure–related risk, and to guide management. The auscultatory technique with a trained observer and mercury sphygmomanometer continues … Accurate measurement of blood pressure is essential to classify individuals, to ascertain blood pressure–related risk, and to guide management. The auscultatory technique with a trained observer and mercury sphygmomanometer continues to be the method of choice for measurement in the office, using the first and fifth phases of the Korotkoff sounds, including in pregnant women. The use of mercury is declining, and alternatives are needed. Aneroid devices are suitable, but they require frequent calibration. Hybrid devices that use electronic transducers instead of mercury have promise. The oscillometric method can be used for office measurement, but only devices independently validated according to standard protocols should be used, and individual calibration is recommended. They have the advantage of being able to take multiple measurements. Proper training of observers, positioning of the patient, and selection of cuff size are all essential. It is increasingly recognized that office measurements correlate poorly with blood pressure measured in other settings, and that they can be supplemented by self-measured readings taken with validated devices at home. There is increasing evidence that home readings predict cardiovascular events and are particularly useful for monitoring the effects of treatment. Twenty-four-hour ambulatory monitoring gives a better prediction of risk than office measurements and is useful for diagnosing white-coat hypertension. There is increasing evidence that a failure of blood pressure to fall during the night may be associated with increased risk. In obese patients and children, the use of an appropriate cuff size is of paramount importance.

Heart Rate Variability and Cardiac Vagal Tone in Psychophysiological Research – Recommendations for Experiment Planning, Data Analysis, and Data Reporting

2017-02-19

Sylvain Laborde , Emma Mosley , Julian F. Thayer

Psychophysiological research integrating heart rate variability (HRV) has increased during the last two decades, particularly given the fact that HRV is able to index cardiac vagal tone. Cardiac vagal tone, … Psychophysiological research integrating heart rate variability (HRV) has increased during the last two decades, particularly given the fact that HRV is able to index cardiac vagal tone. Cardiac vagal tone, which represents the contribution of the parasympathetic nervous system to cardiac regulation, is acknowledged to be linked with many phenomena relevant for psychophysiological research, including self-regulation at the cognitive, emotional, social, and health levels. The ease of HRV collection and measurement coupled with the fact it is relatively affordable, non-invasive and pain free makes it widely accessible to many researchers. This ease of access should not obscure the difficulty of interpretation of HRV findings that can be easily misconstrued, however, this can be controlled to some extent through correct methodological processes. Standards of measurement were developed two decades ago by a Task Force within HRV research, and recent reviews updated several aspects of the Task Force paper. However, many methodological aspects related to HRV in psychophysiological research have to be considered if one aims to be able to draw sound conclusions, which makes it difficult to interpret findings and to compare results across laboratories. Those methodological issues have mainly been discussed in separate outlets, making difficult to get a grasp on them, and thus this paper aims to address this issue. It will help to provide psychophysiological researchers with recommendations and practical advice concerning experimental designs, data analysis, and data reporting. This will ensure that researchers starting a project with HRV and cardiac vagal tone are well informed regarding methodological considerations in order for their findings to contribute to knowledge advancement in their field.

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An Overview of Heart Rate Variability Metrics and Norms

2017-09-28

Fred Shaffer , J. P. Ginsberg

Healthy biological systems exhibit complex patterns of variability that can be described by mathematical chaos. Heart rate variability (HRV) consists of changes in the time intervals between consecutive heartbeats, called … Healthy biological systems exhibit complex patterns of variability that can be described by mathematical chaos. Heart rate variability (HRV) consists of changes in the time intervals between consecutive heartbeats, called interbeat intervals (IBIs). A healthy heart is not a metronome. The oscillations of a healthy heart are complex and constantly changing, which allow the cardiovascular system to rapidly adjust to sudden physical and psychological challenges to homeostasis. This article briefly reviews current perspectives on the mechanisms that generate 24 h, short-term (~5 min), and ultra-short-term (< 5 min) HRV, the importance of HRV, and its implications for health and performance. The authors provide an overview of widely-used HRV time domain, frequency, and nonlinear metrics. Time-domain indices quantify the amount of HRV observed during monitoring periods that may range from ~2 min to 24 h. Frequency-domain values calculate the absolute or relative amount of signal energy within component bands. Nonlinear measurements quantify the unpredictability and complexity of a series of IBIs. The authors survey published normative values for clinical, healthy, and optimal performance populations. They stress the importance of measurement context, including recording period length, subject age, and sex, on baseline HRV values. They caution that 24 h, short-term, and ultra-short-term normative values are not interchangeable. They encourage professionals to supplement published norms with findings from their own specialized populations. Finally, the authors provide an overview of HRV assessment strategies for clinical and optimal performance interventions.

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Stress and Heart Rate Variability: A Meta-Analysis and Review of the Literature

2018-02-27

Hye-Geum Kim , Eun‐Jin Cheon , Dai-Seg Bai +2 more

Objective Physical or mental imbalance caused by harmful stimuli can induce stress to maintain homeostasis. During chronic stress, the sympathetic nervous system is hyperactivated, causing physical, psychological, and behavioral abnormalities. … Objective Physical or mental imbalance caused by harmful stimuli can induce stress to maintain homeostasis. During chronic stress, the sympathetic nervous system is hyperactivated, causing physical, psychological, and behavioral abnormalities. At present, there is no accepted standard for stress evaluation. This review aimed to survey studies providing a rationale for selecting heart rate variability (HRV) as a psychological stress indicator. Methods Term searches in the Web of Science®, National Library of Medicine (PubMed), and Google Scholar databases yielded 37 publications meeting our criteria. The inclusion criteria were involvement of human participants, HRV as an objective psychological stress measure, and measured HRV reactivity. Results In most studies, HRV variables changed in response to stress induced by various methods. The most frequently reported factor associated with variation in HRV variables was low parasympathetic activity, which is characterized by a decrease in the high-frequency band and an increase in the low-frequency band. Neuroimaging studies suggested that HRV may be linked to cortical regions (e.g., the ventromedial prefrontal cortex) that are involved in stressful situation appraisal. Conclusion In conclusion, the current neurobiological evidence suggests that HRV is impacted by stress and supports its use for the objective assessment of psychological health and stress. Keywords: Heart rate variability, Stress, Autonomic nervous system

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Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology.

1996-03-01

Detection of exercise intensity thresholds in patients with chronic heart failure based on correlation properties of heart rate variability

2025-06-25

Noemí Sempere-Ruiz , Agustín Manresa‐Rocamora , Laura Fuertes-Kenneally +5 more | European Journal of Applied Physiology

Abstract Purpose This study aimed to assess the agreement between ventilatory thresholds (VT1 and VT2), and heart rate variability (HRV) thresholds (HRVT1 and HRVT2) based on the alpha 1 index … Abstract Purpose This study aimed to assess the agreement between ventilatory thresholds (VT1 and VT2), and heart rate variability (HRV) thresholds (HRVT1 and HRVT2) based on the alpha 1 index of detrended fluctuation analysis (DFA a1) in patients with chronic heart failure (CHF). Validating HRV-based thresholds could provide a cost-effective alternative for individualised exercise intensity prescription, improving safety and efficacy in exercise-based cardiac rehabilitation (CR) programmes. Methods Twenty CHF patients (13 males, 7 females) performed a cardiopulmonary exercise test (CPET) on a cycle ergometer. Ventilatory thresholds were identified using a mixed method, while HRV thresholds were determined at DFA a1 values of 0.75 (HRVT1) and 0.5 (HRVT2). Threshold values for oxygen consumption (VO 2 ), heart rate (HR), and power output (PO) were compared with paired t test or Wilcoxon test. Agreement was assessed using correlation coefficients (Pearson’s r and Spearman’s rho ), intraclass correlation coefficient (ICC), and Bland–Altman analysis. Results HRVT2 showed moderate-to-strong associations with VT2 for VO 2 ( rho = 0.88, ICC = 0.86), for HR ( r = 0.88, ICC = 0.81) and for PO ( r = 0.82, ICC = 0.85). Mean biases were small and limits of agreement (LoA) narrow. HRVT1 correlated only modestly with VT1 for VO 2 ( rho = 0.67, ICC = 0.43) and weakly for HR ( r = 0.43, ICC = 0.37) and PO ( r = 0.49, ICC = 0.35), with wide LoA. Conclusion In CHF patients, HRVT2 appears to be a valid, practical surrogate for VT2 and may facilitate personalised intensity prescription where full CPET is unavailable. HRVT1 showed insufficient agreement with VT1 and should be used with caution. Larger cohorts and protocol refinements are warranted to confirm these observations and to explore strategies for improving HRVT1 accuracy. Graphical Abstract

Carotid chemoreflex and blood pressure control in young adults with early‐onset hypertension: Considerations for cardiometabolic disease and treatment

2025-06-24

Shaun C. Brazelton , Emma L. Reed , Rauchelle E. Richey +1 more | The Journal of Physiology

Saunieren als neue Therapieoption bei Herzinsuffizienz?

2025-06-24

Peter Overbeck | CardioVasc

Individualized hydration protocol during exercise-based cardiac rehabilitation accelerates acute autonomic recovery in patients with coronary artery disease: crossover clinical trial

2025-06-24

Anne Kastelianne França da Silva , Maria Júlia Lopez Laurino , Lorena Altafin Santos +4 more | Sport Sciences for Health

Reversal of Diabesity Through Modulating Sympathetic Inputs to Adipose Tissue Following Carotid Body Resection

2025-06-24

Bernardete F. Melo , Joana F. Sacramento , Julien Lavergne +7 more | Acta Physiologica

The development of innovative strategies to treat diabesity and its comorbidities is of major societal importance. The carotid bodies (CB), classically defined as O2 sensors, are also metabolic sensors whose … The development of innovative strategies to treat diabesity and its comorbidities is of major societal importance. The carotid bodies (CB), classically defined as O2 sensors, are also metabolic sensors whose dysfunction contributes to the genesis and progression of metabolic disturbances. Here, we tested the hypothesis that the CBs are key players in the neural hypothalamic-sympathetic circuit controlling glucose and energy homeostasis. Moreover, we investigated if abolishment of CB activity has an anti-diabesity effect in Wistar rats and C75BL/6J mice, associated with increased visceral white and brown adipose tissue (AT) metabolism and the restoration of sympathetic activity within these tissues. We demonstrate that resection of the carotid sinus nerve, the CB-sensitive nerve, promotes weight loss and restores metabolic function in obese rats and mice by enhancing tyrosine hydroxylase expression at the paraventricular nucleus of the hypothalamus and its efferent sympathetic neurons to the AT. Moreover, we found that CSN resection increases sympathetic integration and catecholaminergic action in the AT in a manner that restores or even increases AT metabolism. We provide groundbreaking and innovative data showing a new circuit involving the CB-hypothalamus-sympathetic efferents and the AT in controlling glucose and energy homeostasis and so a novel pathway for managing diabesity.

Association Between Melatonin Receptor Agonists and Cardiac Arrhythmia; Disproportionality Analysis Studies Using Pharmacovigilance Databases

2025-06-24

Rikuto Masuda , Yoshihiro Noguchi , Tomoaki Yoshimura | Cardiovascular Toxicology

The cholinergic anti-inflammatory reflex as a function of depression severity in adolescent non-suicidal self-injury

2025-06-24

Thomas P. Nguyen , Luise Baumeister-Lingens , Anna Markser +3 more | The World Journal of Biological Psychiatry

Non-suicidal self-injury (NSSI) is associated with pro-inflammatory states. The cholinergic anti-inflammatory reflex is a neural pathway, modulating the body's inflammatory response. This study aimed to investigate the cholinergic anti-inflammatory reflex … Non-suicidal self-injury (NSSI) is associated with pro-inflammatory states. The cholinergic anti-inflammatory reflex is a neural pathway, modulating the body's inflammatory response. This study aimed to investigate the cholinergic anti-inflammatory reflex in adolescents with and without NSSI in a first, cross-sectional observational study. Heart rate variability (HRV; a proxy for vagus nerve activity), inflammatory markers (leukocytes, c-reactive protein (CRP), interleukin-6 (IL-6)) and several clinical measures were assessed in female adolescents with NSSI (n = 154) and healthy controls (n = 46). Statistical analyses tested for group differences and correlations between HRV, inflammatory markers and depression in patients and controls. Mediation analyses were conducted to test direct and indirect effects. The NSSI group showed greater depressive symptoms and leukocyte levels, but lower HRV compared to the control group. In the full sample, depression severity was positively correlated with leukocyte and CRP levels and negatively correlated with HRV. HRV was also negatively correlated with leukocyte and CRP levels. Depression severity mediated the association between leukocytes and HRV. Overall, this study lends initial support that lower vagal activity is associated with increased inflammatory markers in a sample of adolescents with NSSI which suggests altered functioning of the cholinergic anti-inflammatory reflex.

Utility of nonlinear analysis of heart rate variability in early detection of metabolic syndrome

2025-06-24

José Alberto Zamora-Justo , Myriam Campos-Aguilar , María del Carmen Beas-Jara +5 more | Frontiers in Physiology

Introduction Metabolic syndrome (MetS) is a clinical condition characterized by multiple risk factors that significantly increase the likelihood of developing cardiovascular diseases and type 2 diabetes. Traditional markers, such as … Introduction Metabolic syndrome (MetS) is a clinical condition characterized by multiple risk factors that significantly increase the likelihood of developing cardiovascular diseases and type 2 diabetes. Traditional markers, such as body mass index (BMI) and waist circumference, often fail to detect early metabolic dysfunctions. Methods This study evaluated nonlinear characteristics of heart rate variability (HRV) series, including sample entropy (SampEn), multifractal spectrum parameters, and detrended fluctuation analysis (DFA). A total of 278 participants were classified into three groups: no metabolic alterations, one or two alterations, and MetS (defined as three or more alterations based on ATP III criteria). HRV data were recorded at three time points: rest, exercise, and recovery. Results Participants with MetS showed significantly lower SampEn and DFA values at rest compared to those without alterations, indicating reduced signal complexity. Moreover, a decrease in SampEn was observed in individuals with one or two metabolic alterations, suggesting that autonomic dysfunction may begin in the early stages of metabolic risk. Discussion These findings support the integration of nonlinear HRV analysis with traditional methods to improve the early detection and management of metabolic syndrome. The progressive reduction in heart rate signal complexity may serve as a sensitive marker of early autonomic dysfunction in metabolic deterioration.

The Overlooked Diagnosis: A Case Report on Autonomic Dysfunction and Chronic Dizziness in an Elderly Patient With Neuroimaging Correlation

2025-06-23

Saran AK , Tribhuwan Kumar , Md. Zabihullah +2 more | Cureus

Effectiveness of Physiotherapy Exercise Interventions on Brain Function: A Systematic Review and Neurophysiological Analysis

2025-06-23

PhD Research Sc P. Muthukrishnan , G Shanmugalakshmi , Rajadurai

<title>Abstract</title> At the respective neuroscientific as well as rehabilitation sectors, neurophysiological impacts of therapeutic exercises are attracting more interest. Based on current studies carried out around the globe, structured physical … <title>Abstract</title> At the respective neuroscientific as well as rehabilitation sectors, neurophysiological impacts of therapeutic exercises are attracting more interest. Based on current studies carried out around the globe, structured physical activities that involve resistance exercise, aerobic exercise, or specific to a task motion generate identifiable obtains to the framework, operation, along with neural plasticity for the brain. The present systematic review synthesizes knowledge concerning the mental as well as brain advantages of physical therapy treatments through analysing the worldwide research to 2010 to the year 2024. 42 research, such as meta-analyses as the longitudinal cohort research, along with randomized controlled trials, to different countries have been reviewed employing the guidelines provided by PRISMA. Findings indicate that neurological plasticity processes, such as BDNF expression, the prefrontal cortex participation, the hippocampus weight improvement, and executive functioning recovery, remain regularly triggered, especially among neurological in origin, ageing, as well survivors of strokes population groups. The result globally evaluation points out the therapeutic along with biological importance of rehabilitation for the brain health and supports it’s the incorporation through worldwide rehabilitation regulations.

Regional structural differences in the brain related to high blood pressure

2025-06-23

Donggyu Rim , Tye Dawood , Rania H. Fatouleh +6 more | Journal of Hypertension

Hypertension is characterized by elevations in sympathetic nerve activity that are consistently observed regardless of severity and treatment status. Structural changes in the brain occur with hypertension, including grey matter … Hypertension is characterized by elevations in sympathetic nerve activity that are consistently observed regardless of severity and treatment status. Structural changes in the brain occur with hypertension, including grey matter changes, which are associated with elevated blood pressure (BP). However, whether or not these changes are associated with increased sympathetic nerve activity in hypertensives has not been investigated. The present study aimed to determine the relationship between regional grey matter density, muscle sympathetic nerve activity (MSNA) and BP in people with hypertension, compared to normotensive participants. T1-weighted anatomical scans (3T MRI) were acquired from 35 hypertensive and 57 normotensive participants; MSNA was successfully obtained from the right peroneal nerve in 26 hypertensives and 55 normotensives. Voxel-based morphometry (VBM) analysis was conducted to determine regional grey matter density and the relationships between MSNA and BP in both groups. An inverse relationship between MSNA and grey matter density was found in the left dorsolateral prefrontal cortex, right precentral gyrus, left superior parietal lobule, and right cuneus in hypertensives but not in normotensives. In addition, hypertensive participants showed a negative correlation between grey matter density and DBP in the right precentral gyrus and left postcentral gyrus, which was not observed in controls. We have shown an association between specific nuclei of the brain with elevated MSNA and BP in hypertension. These findings suggest a functional link between grey matter density in specific brain nuclei and MSNA and BP in patients with hypertension.

Subclinical Myocardial Injury and Global Cognitive Performance

2025-06-23

S S Tomar , Kárita Cláudia Freitas Lidani , Aline Moraes +7 more | JACC Advances

The inverse and non-linear association between central augmentation index and heart rate variability in a cohort of male British combat personnel- findings from the ADVANCE study

2025-06-23

Rabeea Maqsood , Susie Schofield , Alexander N. Bennett +5 more | Blood Pressure

The central augmentation index (cAIx) is an indirect measure of arterial stiffness. The influence of heart rate variability (HRV) on cAIx remains unexplored in a military cohort and was the … The central augmentation index (cAIx) is an indirect measure of arterial stiffness. The influence of heart rate variability (HRV) on cAIx remains unexplored in a military cohort and was the aim of this analysis. The first follow-up data from the ArmeD serVices trAuma rehabilitatioN outComE (ADVANCE) study were analysed. Participants were male British servicemen who served in Afghanistan (2003-2014) and were divided into two groups at recruitment: injured (who sustained severe combat injury) and uninjured. The uninjured were frequency-matched to the injured by age, rank, role-in-theatre and deployment. HRV was reported as root-mean-square-of-successive-differences (RMSSD) using a five-minute single-lead electrocardiogram. The cAIx was measured using pulse waveform analysis and was adjusted for heart rate at 60 beats/minute (cAIx@60). Effect modification by injury was assessed via interaction analysis. Linear models reported the association between RMSSD (HRV) and cAIx@60 adjusting for a priori confounders. 1052 participants (injured n = 526; uninjured 526; median age at follow-up 37.4 years) were examined. Effect modification by injury was not statistically significant; therefore, was adjusted for along with other confounders. RMSSD and cAIx@60 exhibited a moderate inverse correlation (-0.40; p < 0.001). The association between natural log-transformed RMSSD (LnRMSSD) and cAIx@60 was non-linear and statistically significant, suggesting that a 10% decrease in LnRMSSD would be associated with 0.30% increase in cAIx@60. Lower RMSSD (HRV) is associated with an increase in cAIx@60, independent of injury status and other traditional cardiovascular risk factors. The efficacy of positive HRV modification on cardiovascular risk in military populations needs to be examined.

Evaluating a brief smartphone-based stress management intervention with heart rate biofeedback from built-in sensors in a three arm randomized controlled trial

2025-06-23

Lukas Fuhrmann , Christian Aljoscha Lukas , Lena Schindler‐Gmelch +1 more | Scientific Reports

The test-retest reliability of the H-Reflex and swaymeter in women aged 30–65 years

2025-06-23

Rosiered Brownson-Smith , John C. Carr , Karen Fox +4 more | PLoS ONE

The H-reflex can objectively assess sensorimotor integration relevant to proprioception and postural control. Chemotherapy-induced peripheral neuropathy (CIPN) is a common and potentially dose-limiting side effect among breast cancer patients undergoing … The H-reflex can objectively assess sensorimotor integration relevant to proprioception and postural control. Chemotherapy-induced peripheral neuropathy (CIPN) is a common and potentially dose-limiting side effect among breast cancer patients undergoing taxane-based treatments, leading to proprioception loss and balance issues, and an increased risk of falling. This study evaluated the between-day test-retest reliability of neurophysiological measures and postural sway, measured via swaymeter in a demographically similar population to those affected by breast cancer. 25 women aged 30-65 years were assessed on two occasions, approximately two weeks apart. The study measured between-day test-retest reliability of the soleus H-reflex and M-wave and postural sway, measured by the swaymeter. The soleus maximum H-reflex amplitude (Hmax) and maximum M-wave amplitude (Mmax) exhibited good to excellent (ICC = 0.92, 95% CI: 0.82-0.96) and moderate to excellent (ICC = 0.81, 95% CI: 0.62-0.91) between-day reliability, respectively. The Hmax/Mmax showed poor to good between-day reliability (ICC = 0.63, 95% CI: 0.31-0.82), and H-reflex latency demonstrated moderate to excellent between-day reliability (ICC = 0.83, 95% CI: 0.65-0.92). The between-day test-retest reliability of anteroposterior (AP) displacement and total sway across the two testing sessions was poor to moderate (ICC = 0.37, 95% CI: -0.03-0.66 and ICC = 0.42, 95% CI: 0.04-0.70, respectively). H-reflex and M-wave measures are reliable for between-day assessments. However, sway measures via swaymeter were less reliable, indicating a need for more robust tools to evaluate balance.

Scaling profiles: A novel diagnostic approach for enhanced characterization of heart rate variability in cardiac pathologies

2025-06-23

Yasunari Fujimoto , Madhur Mangalam , Eiichi Watanabe +1 more | Research Square (Research Square)

<title>Abstract</title> Time series analysis methods, such as Detrended Fluctuation Analysis (DFA) and Detrending Moving-Average Analysis (DMA), estimate scaling exponents and characterize long-range temporal correlations by identifying broad linear regions in … <title>Abstract</title> Time series analysis methods, such as Detrended Fluctuation Analysis (DFA) and Detrending Moving-Average Analysis (DMA), estimate scaling exponents and characterize long-range temporal correlations by identifying broad linear regions in log-log plots of fluctuation magnitude and scale. However, this approach has limitations when applied to complex physiological signals that exhibit transitions from scaling to non-scaling behavior, lack clear scaling properties, or display multiple scaling regimes. Previous research has indicated that long-range temporal correlations in heart rate variability (HRV) differ between healthy individuals and those with cardiovascular conditions such as congestive heart failure and atrial fibrillation. Despite these findings, the full diagnostic performance of scale-dependent variations in these exponents remains unexplored. To address this gap, we introduce a novel “scaling profile” methodology that systematically maps local scaling behavior across various scales and window widths. We preferred DMA for all analyses because DFA yields highly unstable local scaling exponents. We establish the validity of this methodology using simulated processes with known long-range temporal correlations. Applying this method to HRV data from healthy individuals and patients with congestive heart failure and atrial fibrillation demonstrated remarkable diagnostic performance. Specifically, we quantified the diagnostic performance of scaling profiles using receiver operating characteristic (ROC) analysis, revealing patterns of discriminatory power that align with pathophysiological mechanisms underlying different cardiac conditions. Congestive heart failure exhibited good discrimination (maximum area under the curve, AUCmax = 0.889) at smaller window widths and shorter scales, while atrial fibrillation showed excellent discriminatory power with AUCmax ∼ 1, reflecting condition-specific patterns of autonomic modulation. ROC analysis revealed local scaling exponents could effectively discriminate between survivor and nonsurvivor CHF patients ( AUCmax = 0.63) and between AF patients with and without ischemic stroke (AUCmax = 0.64). Kaplan-Meier survival analyses demonstrated significant stratification of highand low-risk CHF patients for mortality (χ2 = 7.07, p = 0.008) and highand low-risk AF patients for ischemic stroke (χ2 = 8.48, p = 0.004) using optimal cutoff values of local scaling exponents, confirming their robust prognostic value across both cardiovascular conditions. Our approach reveals rich dynamical signatures that more comprehensively characterize cardiac pathologies, advancing the theoretical framework and clinical utility of scaling analysis in physiological time series.

Impact of set configurations on hemodynamics, cardiac autonomic, and metabolic responses

2025-06-23

Carlos Brendo Ferreira Reis , Victor Hugo Gasparini Neto , Lucas Rangel Affonso de Miranda +5 more | Retos

Introduction: Isometric exercise (IE) can be used as a non-pharmacologic treatment for blood pressure (BP) reduction. However, the effect of IE set configuration with impulse-to-rest ratio equated on hemodynamic, autonomic, … Introduction: Isometric exercise (IE) can be used as a non-pharmacologic treatment for blood pressure (BP) reduction. However, the effect of IE set configuration with impulse-to-rest ratio equated on hemodynamic, autonomic, and metabolic responses need to be clarified. Objective: This study compared cardiovascular, autonomic, and metabolic responses in two set configurations of IE with an equalized impulse-to-rest ratio. Methodology: Eleven women (25 ± 3 years old) with normal BP values (systolic BP: 112 ± 10 mmHg; diastolic BP: 71 ± 5 mmHg) performed two equalized protocols in the leg press machine on different days in randomized sequence: Long set configuration (LSC: 4 sets x 2 min of isometric contraction x 2 min of rest with 30% 1-RM), and short set configuration (SSC: 16 sets x 30 sec of isometric contraction x 24 sec of rest with 30% 1-RM). Results: During SSC, DBP presented significantly higher values in the first set than LSC (p=0.002). Heart rate, rate pressure product, and cardiac output significantly increased during sets for both protocols. Twenty minutes after protocol, lower values were observed in the mean root square of the successive differences between NN intervals (RMSSD) and mean of the standard deviations for all NN intervals (SDNN) in the LSC configuration in comparison with SSC (p<0.05). In addition, LSC induced significantly higher blood lactate and RPE values during and post-session (p<0.05). Conclusion: The SSC protocol can be better tolerated and targeted for exercise prescription in trained women due to lower hemodynamic, autonomic, and metabolic stress.

Maximum heart rate and mortality in sepsis patients: a retrospective cohort study: comment

2025-06-21

Zhihan Liu , Ziyang Zhou , Cheng Ding +1 more | Internal and Emergency Medicine

Disruptions in cortical circuit connectivity distinguish widespread hyperalgesia from localized pain

2025-06-20

George Kenefati , Mika M. Rockholt , Katherine Eisert +7 more | Frontiers in Pain Research

Introduction This study aims to investigate the interregional functional connectivity in chronic back pain patients with widespread hyperalgesia, patients with localized back pain, and pain-free controls using stimulus-evoked high-density EEG … Introduction This study aims to investigate the interregional functional connectivity in chronic back pain patients with widespread hyperalgesia, patients with localized back pain, and pain-free controls using stimulus-evoked high-density EEG recordings. Methods We conducted high-density EEG recordings to compare the functional connectivity and betweenness centrality between these groups. Results Compared with controls, chronic pain patients showed altered functional connectivity between regions that process cognitive information and regions that process sensory or affective information. Widespread hyperalgesia, however, is further differentiated from localized pain by decreased inter-hemispheric connectivity of sensory and affective areas and increased intra-hemispheric connectivity between sensory and cognitive cortices. Graph-theoretic analysis showed that whereas chronic pain is associated with decreased centrality of prefrontal, orbitofrontal, and cingulate areas, widespread hyperalgesia is distinguished by increased centrality of prefrontal and insular areas. Discussion Together, our results show that although widespread hyperalgesia shares certain features with localized pain, it is further characterized by distinct cortical mechanisms.

Mood alteration and heart rate variability in patients with cancer on treatment

2025-06-20

Yun‐Chen Chang , Wei-Nung Liu , Felicia Lin +1 more | World Journal of Cardiology

In this article, Deng and Song showed compelling evidence on the connection between heart rate variability (HRV) alterations and cancer in 127 cancer patients compared with healthy reference individuals, highlighting … In this article, Deng and Song showed compelling evidence on the connection between heart rate variability (HRV) alterations and cancer in 127 cancer patients compared with healthy reference individuals, highlighting autonomic nervous system dysfunction as a significant physiological manifestation in cancer patients. We discussed that the reduced HRV may be associated with cancer treatments, e.g., operation, chemotherapy and pain control and psychological response such as depression and anxiety related to the affected cancer. A management such as medicine to mood disturbances related to cancer has been shown a benefit to improve HRV in cancer patients.

Heart rate transition patterns reveal autonomic dysfunction in heart failure with renal function decline: a symbolic and Markov model approach

2025-06-20

Namareq Widatalla , Sidra Younis , Ahsan H. Khandoker | BioData Mining

Around half of heart failure (HF) patients develop chronic kidney disease (CKD) and early detection of renal impairment in HF remains a clinical challenge. Both HF and CKD are characterized … Around half of heart failure (HF) patients develop chronic kidney disease (CKD) and early detection of renal impairment in HF remains a clinical challenge. Both HF and CKD are characterized by autonomic dysfunction, suggesting that early identification of autonomic dysregulation may assist in early diagnosis and intervention. Conventional heart rate variability (HRV) metrics serve as non-invasive markers of autonomic nervous system (ANS) function; however, they are limited in their ability to capture directional and nonlinear dynamics associated with autonomic impairment during renal function decline. In this study, we digitized heart rate (HR) changes from 5-minute electrocardiogram (ECG) recordings in 358 patients with chronic HF (CHF). We applied a first-order Markov model and motif pattern analyses to compare HR transition dynamics between patients with normal and reduced estimated glomerular filtration rate (eGFR). The results revealed decreased monotonic HR transitions and increased tonic fluctuations in patients with reduced eGFR. Building on these findings, we introduced a transition stability index (TSI), which was significantly lower in patients with reduced eGFR compared to those with normal eGFR (p < 0.05). These results suggest that TSI may serve as a novel indicator of autonomic dysfunction associated with renal decline. Motif analysis further supported these findings by identifying distinctive HR transition patterns in patients with low eGFR.

Stress Scores and S/PS Ratio as Noninvasive Marker for Evaluation of Sympathovagal Balance in Progressive Atherosclerotic Plaque

2025-06-20

Rahul Kumar , Akanksha Kumari , Yogender Aggarwal | Journal of Clinical Engineering

The utilization of stress scores (SS) as markers of sympathetic nervous system activity and the S/PS ratio, representing the balance between sympathetic and parasympathetic activity, has emerged as a novel … The utilization of stress scores (SS) as markers of sympathetic nervous system activity and the S/PS ratio, representing the balance between sympathetic and parasympathetic activity, has emerged as a novel approach in cardiovascular research. High-fat diets (HFD) have been shown to dysregulate autonomic function, leading to increased lipid markers, atherogenic indices, and the progression of atherosclerosis. Recent studies have highlighted the correlation between elevated stress scores, higher S/PS ratios, and the risk of atherosclerosis in individuals with carotid artery plaques. Reduced heart rate variability, observed in HFD-fed subjects, further underscores the link between autonomic imbalance and plaque formation. Notably, the SS and S/PS ratio have demonstrated utility as biomarkers in assessing autonomic nervous system anomalies in both healthy and sedentary individuals. The significant positive correlation of SS and S/PS ratios with lipid markers and atherogenic indices suggests their potential in monitoring atherosclerotic progression and dyslipidaemia risk. These findings support the use of noninvasive autonomic biomarkers to better understand the interplay between stress, lipid metabolism, and cardiovascular health, offering a promising tool for identifying individuals at heightened risk of atherosclerotic diseases.

ANALYSIS OF RECOVERY PATTERNS OF HEART RATE AND RESTING PULSE RATE AMONG ATHLETES IN DIVERSE SPORTS AFTER STRENUOUS EXERCISE

2025-06-20

Manjula Manikandan , Dr.M.Ramajayam | EPRA International Journal of Research & Development (IJRD)

This study investigates the recovery patterns of athletes across diverse sports disciplines following strenuous exercise, with a focus on variations in recovery heart rate and resting pulse rate. To achieve … This study investigates the recovery patterns of athletes across diverse sports disciplines following strenuous exercise, with a focus on variations in recovery heart rate and resting pulse rate. To achieve this study sixty (N=60) athletes aged 18 to 25 years were selected from the Ramakrishna Mission Vivekananda Educational and Research Institute, faculty of general adapted physical education and yoga, Coimbatore. Representing four sports: basketball, football, handball, and hockey, with fifteen participants from each discipline. All the different sports disciplines treadmill run for 8 minutes. After the exercise between the rest intervals recovery heart rate were checked all the sports disciplines. The pre and post data analysis was conducted using one-way ANOVA to determine significant differences in recovery rates across the among the sports if obtained F ratio is significant the Scheffé post hoc test was employed to identify specific group differences, with a significance level fixed at 0.05.the result of the shows that no significance difference resting pulse rate among four different disciples. There is a significant different between recovery heart rate. Basketball players better recovery heart rate compere with handball players, hockey players, and football players. Keywords: Recovery Heart Rate, Resting Pulse Rate

Is gaming stress or Relaxation? An HRV-Based Investigation of physiological responses in young adults

2025-06-20

André Alesi , Kristina Klier , Benedict Herhaus +4 more | Entertainment Computing

Author Response: “Re: Comprehensive linear and nonlinear heart rate variability normative data in children. Clinical Autonomic Research (September 2024)”

2025-06-20

Bahram Kakavand | Clinical Autonomic Research

Non-linear heart rate variability is sensitive to exercise duration but not indicative of acute performance decrement

2025-06-20

Oluwatimilehin O. Ajayi , Cody R. van Rassel , Matthew J. Jordan +1 more | European Journal of Applied Physiology

Assessing the effect of arousal on performance in a virtual reality narrative scenario using biological signals

2025-06-20

D. E. Archer , C. C. Li , Guang Chen +2 more | Frontiers in Virtual Reality

When analysing a user’s experience of virtual reality (VR), factors such as their level of technical familiarity, proficiency with immersive technology and concomitant degree of physiological arousal inside a VR … When analysing a user’s experience of virtual reality (VR), factors such as their level of technical familiarity, proficiency with immersive technology and concomitant degree of physiological arousal inside a VR experience can have a significant impact on their performance, sense of presence and engagement. We have designed a modular narrative system to manipulate a user’s levels of arousal in order to keep them within an optimal range for performance, which we hypothesise to be between not too stressed (high arousal) and not too bored (low arousal). We do so by instantiating an increasing number of simultaneous tests and environmental changes at different points during a VR experience. Changes in autonomic signals - such as heart rate, heart rate variability, galvanic skin response, and skin temperature - reveal changes in the levels of participant arousal. The user is embodied in a gender-specific out-group (Muslim) avatar that is subjected to an increasingly stressful event (a series of verbal Islamophobic attacks from a non-player character). We measure performance in a series of simultaneous multiple choice listening comprehension tasks (averaged to create a “narrative task score”) undertaken as the scene unfolds, and a post-treatment recall task. As a pilot experiment, our primary objective is to validate the effectiveness of the system as a means of stress manipulation and thereby assess the impact and correlation that different levels of arousal have on task performance and biological signals. Results revealed a statistically significant difference in narrative task performance between stress levels, confirmed by a one-way ANOVA ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mi>F</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mn>2,45</mml:mn></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mn>5.06</mml:mn></mml:mrow></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.02</mml:mn></mml:mrow></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"><mml:mrow><mml:mi>S</mml:mi><mml:mi>E</mml:mi><mml:mo>=</mml:mo><mml:mn>23.89</mml:mn></mml:mrow></mml:math> ). The low stress group achieved the highest mean VR score ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"><mml:mrow><mml:mi>M</mml:mi><mml:mo>=</mml:mo><mml:mn>73.12</mml:mn></mml:mrow></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mrow><mml:mi>S</mml:mi><mml:mi>D</mml:mi><mml:mo>=</mml:mo><mml:mn>15.96</mml:mn></mml:mrow></mml:math> ), followed by the high ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m6"><mml:mrow><mml:mi>M</mml:mi><mml:mo>=</mml:mo><mml:mn>63.25</mml:mn></mml:mrow></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m7"><mml:mrow><mml:mi>S</mml:mi><mml:mi>D</mml:mi><mml:mo>=</mml:mo><mml:mn>18.23</mml:mn></mml:mrow></mml:math> ) and medium stress groups ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m8"><mml:mrow><mml:mi>M</mml:mi><mml:mo>=</mml:mo><mml:mn>51.81</mml:mn></mml:mrow></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m9"><mml:mrow><mml:mi>S</mml:mi><mml:mi>D</mml:mi><mml:mo>=</mml:mo><mml:mn>23.66</mml:mn></mml:mrow></mml:math> ). Our hypothesis that the medium stress condition would produce the best performance was therefore rejected. Comparing heart rate variability (HRV) metrics, the Stress Index showed a statistically significant difference between conditions ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m10"><mml:mrow><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.043</mml:mn></mml:mrow></mml:math> , with significant within-condition changes also observed in the LF/HF ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m11"><mml:mrow><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.005</mml:mn></mml:mrow></mml:math> in low stress and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m12"><mml:mrow><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.008</mml:mn></mml:mrow></mml:math> in high stress), further demonstrating the physiological changes between stress levels.

Early Detection of the Marathon Wall to Improve Pacing Strategies in Recreational Marathoners

2025-06-19

Mohamad-Medhi El Dandachi , Véronique Billat , Florent Palacin +1 more | AI

The individual marathon optimal pacing sparring the runner to hit the “wall” after 2 h of running remain unclear. In the current study we examined to what extent Deep neural … The individual marathon optimal pacing sparring the runner to hit the “wall” after 2 h of running remain unclear. In the current study we examined to what extent Deep neural Network contributes to identify the individual optimal pacing training a Variational Auto Encoder (VAE) with a small dataset of nine runners. This last one has been constructed from an original one that contains the values of multiple physiological variables for 10 different runners during a marathon. We plot the Lyapunov exponent/Time graph on these variables for each runner showing that the marathon wall could be anticipated. The pacing strategy that this innovative technique sheds light on is to predict and delay the moment when the runner empties his reserves and ’hits the wall’ while considering the individual physical capabilities of each athlete. Our data suggest that given that a further increase of marathon runner using a cardio-GPS could benefit of their pacing run for optimizing their performance if AI would be used for learning how to self-pace his marathon race for avoiding hitting the wall.

The Effects of Blood Flow Restriction Exercise on Muscle–Brain Crosstalk: A Systematic Review

2025-06-19

Josh Landers , Kelly Landers , Nilas Young | Muscles

Blood flow restriction exercise (BFRE), which partially restricts arterial inflow and occludes venous outflow to the limbs, has gained attention for its potential to elevate serum brain-derived neurotrophic factor (BDNF), … Blood flow restriction exercise (BFRE), which partially restricts arterial inflow and occludes venous outflow to the limbs, has gained attention for its potential to elevate serum brain-derived neurotrophic factor (BDNF), a key mediator in the muscle–brain crosstalk leading to improvement of neuroplasticity, neurogenesis, and cognitive health. In this systematic review of five studies, participants included healthy young adults, older adults, and individuals with clinical conditions. Most investigations found that BFRE increased serum BDNF, with responses comparable to those elicited by high-intensity exercise. Proposed mechanisms center on the metabolic demands of BFRE, which may increase lactate and thereby trigger BDNF release. However, two studies showed no significant changes, possibly due to short exercise duration, insufficient training intensity, or age-related reductions in BDNF responsiveness. The small sample sizes and varied protocols across studies limit definitive conclusions. Nonetheless, BFRE may provide a valuable alternative for populations who cannot tolerate high mechanical loads, and it shows promise for enhancing neurotrophic support and potentially improving brain health. Larger, well-controlled trials are warranted to refine BFRE protocols and better understand optimal strategies for increasing BDNF and supporting neuroplasticity.

Associations between cardiac autonomic function and cognition across the adult female lifespan

2025-06-19

Alicia Duval , Blaine Ditto | Autonomic Neuroscience

Assessment of Heart Rate Variability Among Plant Nursery Workers

2025-06-19

Ornwipa Thamsuwan , Katia Cherik | Journal of Agromedicine

Work-related stress has become prevalent among workers in various occupational sectors, including agriculture. This study assessed stress among seasonal migrant workers at a plant nursery throughout their full work shift. … Work-related stress has become prevalent among workers in various occupational sectors, including agriculture. This study assessed stress among seasonal migrant workers at a plant nursery throughout their full work shift. The study included nine participants who performed a variety of tasks during the measurement day. Their beat-to-beat heart intervals were continuously collected using a heart rate monitor and mobile application. Their stress at work was then characterized in terms of heart rate variability (HRV) parameters (Mean RR, SDNN [Standard Deviation of NN], RMSSD [Root Mean Square of Successive Differences], VLF [Very Low Frequency] Power, LF [Low Frequency] Power, HF [High Frequency] Power, Total Power, VLF%, LF%, HF%, LF n.u. HF n.u. and LF:HF Ratio) using the Kubios HRV software. Generalized linear mixed-effects models were used to determine the effect of time of day since work began (partitioned into 15-min windows) and the assigned job tasks. Time of day was found to reduce Mean RR, SDNN, RMSSD, LF, HF, and Total Power, while increasing the LF:HF ratio, indicating stress increased as the workday progressed. Some job tasks had a significant impact on workers' stress levels. The task of field maintenance, including trimming bushes and sweeping cut branches, resulted in an increase in workers' stress. Conversely, weeding appeared to decrease SDNN, RMSSD, and VLF Power, suggesting this activity reduced stress. This study demonstrated the feasibility of assessing heart rate variability in the field, providing objective data to decision-makers. To the authors' knowledge, this study is among the first to evaluate agricultural workers' stress using direct physiological measures such as heart rate variability.

Brain endurance training as a strategy for reducing mental fatigue

2025-06-18

Nathalie André , Michel Audiffren , Chris Englert | Frontiers in Psychology

Mental fatigue is a psychobiological state triggered by sustained mental effort, affecting subjective parameters, performance, and physiological responses. It impairs sports performance across various disciplines. Individual differences in mental fatiguability … Mental fatigue is a psychobiological state triggered by sustained mental effort, affecting subjective parameters, performance, and physiological responses. It impairs sports performance across various disciplines. Individual differences in mental fatiguability and physical fitness may moderate the effects of mental fatigue. Initial evidence suggests that endurance athletes are more resilient to the decrease in the capacity and/or willingness to deploy mental effort induced by mental fatigue, though the results are mixed. Brain Endurance Training (BET) aims to enhance resistance to mental fatigue by combining cognitive and physical training. BET typically uses dual-task designs (simultaneous mental and physical effort), which appear more effective than sequential-task designs. Cognitive tasks involved in brain endurance training often target executive functions, like sustained attention and inhibitory control. While BET consistently improves endurance performance, its effects on subjective mental fatigue are currently less conclusive, which offers intriguing possibilities for future research. Other outcomes, such as perceived exertion and brain oxygenation, suggest BET reduces the cognitive cost of mental and physical effort. BET may also influence brain networks related to attention and self-regulation, particularly the salience network, default mode network (DMN), and frontoparietal network (FPN). Functional connectivity studies hint that BET could lead to beneficial changes in how these networks interact, potentially reducing DMN activity and enhancing control by task-positive networks. Although evidence is still emerging, early findings support BET as a promising intervention to reduce the likelihood of getting mentally fatigued and improve endurance performance in cognitively demanding contexts. Future research should refine BET protocols and explore its underlying neural mechanisms using imaging techniques.

RESISTANCE TRAINING HEMODYNAMIC IMPROVEMENT CARDIOVASCULAR IN THE ELDERLY: INVOLVING AUTONOMIC BALANCE AND IMMUNE SYSTEM

2025-06-18

Eduarda Teodora Rachid Wolpp , Anamei Silva-Reis , Marianna F. Maia +1 more | CIPEEX

The study evaluated the effects of resistance training on the cardiovascular and immunological health of the elderly. Sixty-nine participants were randomly divided into a control group and a training group, … The study evaluated the effects of resistance training on the cardiovascular and immunological health of the elderly. Sixty-nine participants were randomly divided into a control group and a training group, which performed resistance exercises three times a week for 12 weeks. The pre- and post-training assessments included measurements of heart rate, blood pressure, and hemodynamic analysis by impedance cardiography. Inflammatory biomarkers and functional capacity were also analyzed. The results showed that resistance training significantly improved various cardiovascular parameters, such as increased stroke volume, cardiac output, and heart rate variability, as well as reduced systemic vascular resistance. There were also improvements in respiratory muscle strength and functional capacity, with an increase in the number of repetitions in the sit-to-stand test and the elimination of oxygen desaturation during the test. Additionally, the training promoted positive effects on the immune system, reducing levels of interleukin 6 and tumor necrosis factor alpha, and increasing interleukin 10 and Klotho. It is concluded that resistance training can be an effective intervention to improve cardiovascular hemodynamics, autonomic balance, and immune response in the elderly, as well as enhance muscle strength and functional capacity, thereby promoting healthier aging.

Sympathetic Overactivation in the Resistant Hypertensive Phenotype: A Meta-Analysis of Published Studies

2025-06-18

Guıdo Grassı , Fosca Quartı-Trevano , Cesare Cuspidi +3 more | Hypertension

BACKGROUND: Indirect and direct approaches to assess sympathetic cardiovascular drive have shown that patients with essential hypertension responsive to the blood pressure–lowering effects of antihypertensive drugs are characterized by a … BACKGROUND: Indirect and direct approaches to assess sympathetic cardiovascular drive have shown that patients with essential hypertension responsive to the blood pressure–lowering effects of antihypertensive drugs are characterized by a pronounced adrenergic overactivity. Whether an emerging clinical hypertensive phenotype such as drug-resistant hypertension (RHT) is also characterized by sympathetic activation and whether its magnitude and underlying pathophysiological mechanisms differ from those of non-RHT is undefined. METHODS: Among the 54 studies identified providing information in RHT on muscle sympathetic nerve traffic (MSNA), 12 were eligible (508 patients) and meta-analyzed, grouping them based on clinically relevant questions: (1) Is MSNA increased in RHT? (2) Does the magnitude of the sympathetic activation differ from that observed in non-RHT? (3) Are heart rate and plasma norepinephrine valuable surrogate markers of MSNA in RHT? and (4) Is baroreflex-MSNA control impaired? RESULTS: MSNA was significantly greater in patients with RHT than in normotensive patients (73.2±6.6 versus 46.1±11.1 bursts/100 heartbeats, means±SD; P <0.0001) and this was the case also when data were compared with patients with non-RHT (59.8±8.4 bursts/100 heartbeats; P <0.001), despite the greater number of antihypertensive drugs. At variance from non-RHT, in RHT, elevated MSNA was unrelated to heart rate and plasma venous norepinephrine. Similar to non-RHT, MSNA in RHT was inversely related to the baroreflex function. CONCLUSIONS: RHT is characterized by a sustained sympathetic overdrive, significantly greater in magnitude than the 1 detected in non-RHT. Neither heart rate nor norepinephrine are capable of reflecting the marked adrenergic overdrive seen in this condition via MSNA recordings.

Hypoxia disrupts neurovascular regulation of blood pressure in normotensive and untreated hypertensive men

2025-06-18

Qudus A Ojikutu , Jeann L. Sabino‐Carvalho , Katherine Latham +7 more | Clinical Autonomic Research

The relationship between sleep quality and cardiac autonomic modulation according to physical activity levels in adults: a cross-sectional study

2025-06-17

Lucas J Onimaru , Diego Giulliano Destro Christófaro , Heloísa Balotari Valente +7 more | Sleep And Breathing

HRV and blood parameters for assessing the physiological functioning of cyclists during long-distance rides across different altitudes

2025-06-17

William W. Du , Ming Zhang , Xiaodan Niu +2 more | Frontiers in Physiology

Objective This study aimed to systematically investigate the changes and interrelationships between heart rate variability (HRV) and hematological parameters in cyclists during prolonged exposure to varying altitudes, in order to … Objective This study aimed to systematically investigate the changes and interrelationships between heart rate variability (HRV) and hematological parameters in cyclists during prolonged exposure to varying altitudes, in order to reveal the dynamic interplay between autonomic nervous system regulation and hematological adaptation. Methods Seventeen cycling enthusiasts aged 16–25 years participated in an 8-day altitude cycling challenge. HRV and hematological parameters were measured at three altitudes: 485 m, 1,627 m, and 4,182 m. Results Hematological parameters, including white blood cell count (WBC), hemoglobin concentration (HGB), hematocrit (HCT), mean corpuscular hemoglobin concentration (MCHC), platelet count (PLT), and plateletcrit (PCT), significantly increased at both 1,627 m and 4,182 m (P &lt; 0.05). Physiological measures such as heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) showed significant elevations at 4,182 m (P &lt; 0.05), while vital capacity (VC) significantly decreased (P &lt; 0.05). HRV time-domain indices, including the standard deviation of R–R intervals (SDNN) and the root mean square of successive R–R interval differences (RMSSD), significantly increased at 1,627 m (P &lt; 0.05) but decreased at 4,182 m (P &lt; 0.05). Frequency-domain indices, including very low-frequency power (VLF), low-frequency power (LF), and high-frequency power (HF), significantly decreased at 4,182 m (P &lt; 0.01). Among nonlinear HRV metrics, the short-term standard deviation of the Poincaré plot (SD1) and long-term standard deviation (SD2) significantly decreased at 4,182 m (P &lt; 0.01), while approximate entropy (ApEn), sample entropy (SampEn), and alpha2 significantly increased (P &lt; 0.05). Correlation analysis revealed that at 485 m, SDNN was negatively correlated with HCT (r = −0.55, P &lt; 0.05) and PLT (r = −0.50, P &lt; 0.05), while LF and HF were negatively correlated with HCT (r = −0.55 and −0.54, P &lt; 0.05). At 1,627 m, SDNN was positively correlated with MCV (r = 0.53, P &lt; 0.05), LF with MCV (r = 0.23, P &lt; 0.05), and LF/HF was negatively correlated with MCHC (r = −0.52, P &lt; 0.05). At 4,182 m, SDNN was positively correlated with MCHC (r = 0.51, P &lt; 0.05), VLF was negatively correlated with WBC (r = −0.63, P &lt; 0.05), ApEn was positively correlated with both WBC (r = 0.76, P &lt; 0.05) and HCT (r = 0.62, P &lt; 0.05), and SampEn was positively correlated with WBC (r = 0.74, P &lt; 0.05). Conclusion This study systematically evaluated the dynamic changes in HRV and hematological parameters in cyclists during prolonged exposure to different altitudes. The results showed that at moderate altitude, athletes exhibited a coordinated response of enhanced short-term autonomic adaptation and increased red blood cell volume. At very high altitude, HRV decreased overall while its complexity increased, indicating a stress-compensatory mechanism dominated by sympathetic activation. Altitude-specific correlations between HRV and blood parameters suggest a potential interplay between autonomic regulation and hematological adaptation.

From reflex to relief: modifying the muscle metaboreflex in heart failure

2025-06-17

Seth W. Holwerda | The Journal of Physiology

Sleep in Juvenile Idiopathic Arthritis: An Exploratory Investigation of Heart Rate Variability

2025-06-17

Maria Cecília Lopes , Suely Roizenblatt , Leticia Azevedo Soster +1 more | Brain Sciences

Introduction: The monitoring of autonomic nervous balance during childhood remains underexplored. However, heart rate variability (HRV) is widely recognized as a biomarker of health risk across the lifespan. Juvenile idiopathic … Introduction: The monitoring of autonomic nervous balance during childhood remains underexplored. However, heart rate variability (HRV) is widely recognized as a biomarker of health risk across the lifespan. Juvenile idiopathic arthritis (JIA), a group of chronic inflammatory joint disorders, is associated with persistent inflammation and pain, both of which contribute to increased cardiovascular risk, commonly linked to reduced HRV. Among HRV parameters, very-low frequency (VLF) components have been associated with physiological recovery processes. This study aimed to assess HRV during sleep in patients with JIA. Methods: We studied 10 patients with JIA and 10 age-, gender-, and Tanner stage-matched healthy controls. All participants underwent polysomnographic monitoring following an adaptation night in the sleep laboratory. HRV was analyzed using standard time and frequency domain measures over 5 min epochs across all sleep stages. Frequency components were classified into low- and high-frequency bands, and time domain measures included the standard deviation of the beat-to-beat intervals. Group differences in HRV parameters were assessed using nonparametric tests for independent samples, with a significance level set at p < 0.05. Results: JIA exhibited greater sleep disruption than controls, including reduced NREM sleep, longer total sleep time, and increased wake time after sleep onset. HRV analyses in both time and frequency domains revealed significant differences between groups across all stages of sleep. In JIA patients, the standard deviation of the normal-to-normal interval during slow wave sleep (SWS) and total power across all sleep stages (p < 0.05) was reduced. In JIA patients, the standard deviation of the normal-to-normal interval during slow wave sleep and total power across all sleep stages were significantly reduced (p < 0.05). VLF power was also significantly lower in JIA patients across all sleep stages (p = 0.002), with pronounced reductions during N2 and SWS (p = 0.03 and p = 0.02, respectively). A group effect was observed for total power across all stages, mirroring the VLF findings. Additionally, group differences were detected in LF/HF ratio analyses, although values during N2, SWS, and REM sleep did not differ significantly between groups. Notably, the number of affected joints showed a moderate positive correlation with the parasympathetic HRV parameter. Conclusions: Patients with JIA exhibited sleep disruption and alterations in cardiovascular autonomic functioning during sleep. Reduced HRV across all sleep stages in these patients suggests underlying autonomic nervous dysfunction. Addressing sleep disturbances in patients with chronic pain may serve as an effective strategy for managing their cardiovascular risk.

Optimizing Heart Rate Variability Detection: An Algorithm for Enhanced ECG and PPG Measurements

2025-06-17

Hyuk-Jae Kwon , Jong Hyun Baek , Cheong Hoon Seo +6 more | Journal of Electrical Engineering and Technology

Short-term reduction in sleep irregularity modulates cardiac autonomic function and central hemodynamic parameters at rest

2025-06-17

Joaquin U. Gonzales , Gabriel Narváez | Sleep Medicine

Analysis of the neural mechanisms of social anxiety based on EEG features and machine learning and construction of a diagnostic model

2025-06-16

Zhi Ma , Zhixiong Yan , Fengqin Ding | International Journal of Psychophysiology

Stabilization of the human heartbeat using adaptive controller-based optimized deep policy gradient

2025-06-16

Khalid A. Alattas | Computers in Biology and Medicine

Influence of Carotid Intima Media Thickness on The Patient's Memory Function Fails Heart with Ejection Fraction Left Ventricle Descends

2025-06-16

Aurelia Sartika Tongku , Junita Maja Pertiwi , Gilbert Tangkudung +2 more | Eduvest - Journal Of Universal Studies

Heart failure (HF) with reduced left ventricular ejection fraction (LVEF) is frequently associated with cognitive decline, including memory impairment. This study investigates the relationship between carotid intima-media thickness (CIMT), a … Heart failure (HF) with reduced left ventricular ejection fraction (LVEF) is frequently associated with cognitive decline, including memory impairment. This study investigates the relationship between carotid intima-media thickness (CIMT), a marker of subclinical atherosclerosis, and specific memory domains immediate, recall, and recognition in patients with reduced LVEF. A cross-sectional study was conducted on 52 HF patients at Prof. Dr. R.D. Kandou Hospital. Memory function was assessed using the Word List Memory Test, and CIMT was measured via carotid ultrasound. Regression analysis showed that increased CIMT in the left common carotid artery (CCA Sinistra) was significantly associated with lower immediate and recognition memory performance. Furthermore, elevated CIMT in both carotid arteries was negatively correlated with recall memory. These findings highlight a potential vascular contribution to cognitive impairment in HF patients, suggesting that subclinical carotid atherosclerosis may impair cerebral perfusion. The study provides clinical insight into the importance of vascular assessment in managing cognitive health in HF populations. Early detection of carotid pathology may offer a strategy to prevent or reduce cognitive decline in these patients.

Validity of resting heart rate derived from contact-based smartphone photoplethysmography (PPG) compared with electrocardiography (ECG): Protocol for a Systematic Review and Meta-Analysis

2025-06-16

James D. Mather , Nicholas Sculthorpe , Nilihan E. M. Sanal‐Hayes +3 more | medRxiv (Cold Spring Harbor Laboratory)

Objective To synthesise quantitative evidence on the validity of photoplethysmography (PPG) derived from mobile devices (i.e. smartphones) for the assessment of heart rate (HR) compared to the gold standard electrocardiogram … Objective To synthesise quantitative evidence on the validity of photoplethysmography (PPG) derived from mobile devices (i.e. smartphones) for the assessment of heart rate (HR) compared to the gold standard electrocardiogram (ECG). Introduction Mobile health (mHealth), the use of mobile devices for promotion or measurement of health is on the rise. Smartphone cameras can perform photoplethysmography (PPG) for the assessment of heart rate (HR) and other cardiac cycle characteristics. However, rigorous validity is necessary before smartphone measurement of PPG can be utilized for healthcare provision. There is a pervasive belief that HR-PPG is analogous to HR-ECG, and herein we will provide an updated systematic review and meta- analysis to support or challenge this supposition. Inclusion criteria This review will include studies that investigate the correlation coefficient between of resting heart rate (RHR) acquisition from PPG utilizing contact-based smartphone devices versus ECG as the gold standard, Studies will be excluded if they (a) do not use PPG utilizing contact-based smartphone devices (b) compare PPG to another collection method other than ECG, or (c) are review articles or case studies. Methods A comprehensive literature search will be conducted in CINAHL Ultimate, MEDLINE, ScienceDirect, and Scopus using a search strategy developed in collaboration with the research team. All retrieved citations will be imported into Rayyan for screening and data management. A minimum of two independent reviewers will conduct the title and abstract screening, followed by two independent reviewers who will perform full-text screening and data extraction. All stages will be guided by predefined inclusion and exclusion criteria, which will be pilot tested to ensure consistency and reliability. Any discrepancies will be resolved through discussion with a third reviewer or during a research team meeting. Intra-rater reliability will be quantified at the title and abstract stage, and the full-text review stage using Cohen’s Kappa. To ensure clarity and consistency in the presentation of study characteristics and findings, both narrative synthesis and tabular formats will be employed. Review registration https://doi.org/10.17605/OSF.IO/83V7A

Monitoring nociception in patients with morbid obesity undergoing bariatric surgery

2025-06-16

Salvatore Fabrizio Favitta , Danilo Santolamazza , Ersilia Luca +2 more | Saudi Journal of Anaesthesia

Bariatric surgery is a rapidly developing field and presents a challenge for anesthesia management, especially in the treatment of acute postoperative pain. Severely obese patients have a greater risk of … Bariatric surgery is a rapidly developing field and presents a challenge for anesthesia management, especially in the treatment of acute postoperative pain. Severely obese patients have a greater risk of intra and postoperative complications due to their cardiovascular and respiratory pathophysiological alterations. Excessive fat also alters the normal metabolism of analgesic drugs, in particular opioids, thus reducing their therapeutic range and increasing the risk of reaching toxic doses with accumulation and overdose effects. Nociception, in contrast to pain, is not a subjective experience but a physiological response to a nociceptive stimulus, which manifests as objective modifications in vital parameters. An increasing number of monitoring methods have been approved in recent years, especially developed for the detection of intraoperative nociception to enable better control of opioid titration. This review aimed to provide an overview of the main monitoring systems commercially available devices, which could be used to monitor nociception during bariatric surgery. Eighteen studies evaluating the most widespread nociception monitoring systems were analyzed. These studies were mostly conducted on patients undergoing abdominal laparoscopic surgery, which is comparable to bariatric surgery in terms of pain stimulation. Intraoperative and postoperative opioid consumption were compared between patients subject to nociceptive monitoring and those in whom analgesia was guided by their changes in vital parameters. Although the devices seem able to optimize the anesthetic management of these patients, studies on bariatric populations are scarce and do not allow us to state whether the routine use of these tools can modify the patient’s clinical outcome.