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

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

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

One-dimensional, nonlinear determinism characterizes heart rate pattern during paced respiration

1998 ◽  
Vol 275 (3) ◽  
pp. H1092-H1102 ◽  
Author(s):  
Katrin Suder ◽  
Friedhelm R. Drepper ◽  
Michael Schiek ◽  
Hans-Henning Abel
Keyword(s):  
Heart Rate ◽  
Time Series ◽  
Heart Rate Variability ◽  
Respiratory Sinus Arrhythmia ◽  
Sinus Arrhythmia ◽  
Dynamic Pattern ◽  
One Dimensional ◽  
Circle Maps ◽  
Paced Respiration ◽  
Heart Rate Pattern

This study focuses on the dynamic pattern of heart rate variability in the frequency range of respiration, the so-called respiratory sinus arrhythmia. Forty experimental time series of heart rate data from four healthy adult volunteers undergoing a paced respiration protocol were used as an empirical basis. For pacing-cycle lengths >8 s, the heartbeat intervals are shown to obey a rule that can be expressed by a one-dimensional circle map (next-angle map). Circle maps are introduced as a new type of model for time series analyses to characterize the nonlinear dynamic pattern underlying the respiratory sinus arrhythmia during voluntary paced respiration. Although these maps are not chaotic, the dynamic pattern shows typical imprints of nonlinearity. By starting from a piecewise linear model, which describes the different circle maps obtained from the empirical time series for various pacing frequencies, time invariant measures can be introduced that characterize the dynamic pattern of heart rate variability during voluntary slow-paced respiration.

On the fractal nature of heart rate variability in humans: effects of vagal blockade

1995 ◽  
Vol 269 (4) ◽  
pp. R830-R837 ◽  
Author(s):  
Y. Yamamoto ◽  
Y. Nakamura ◽  
H. Sato ◽  
M. Yamamoto ◽  
K. Kato ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Harmonic Component ◽  
Coarse Graining ◽  
Normal Subjects ◽  
Atropine Sulfate ◽  
Total Power ◽  
Scaling Exponent ◽  
Fractal Nature ◽  
Mean Values

The purpose of the present study was to investigate the effects of the vagal blocker atropine on the fractal nature of human heart rate variability (HRV) at rest. Approximately 10-min segments of beat-to-beat heartbeat intervals, i.e., HRV, of 10 normal subjects and 11 cardiac disease patients were measured before and after intravenous injection of 0.5-0.75 mg atropine sulfate. HRV data were analyzed by coarse graining spectral analysis (Y. Yamamoto and R. L. Hughson, Physica 68D: 250-264, 1993) to break down their total power into harmonic and nonharmonic (fractal) components. The harmonic component was used to calculate the contribution of high (> 0.15 Hz)-frequency components to total HRV power (%HF). From the fractal component, the contribution of the fractal component to total HRV power (%fractal), the spectral exponent beta, and Hurst scaling exponent (H) were calculated. For both normal subjects and cardiac patients, atropine resulted in significantly (P < 0.05) less mean HRV and significantly (P < 0.05) greater beta compared with control, whereas mean values for %fractal were as high as 70% and were not significantly (P > 0.05) different between atropine and control. The mean value of H with atropine was significantly (P < 0.05) greater than that for control. Directional changes in %HF and beta were consistent with only one exception for a patient who had the smallest change in log %HF by atropine. The normally irregular fractal pattern of resting HRV was decreased by atropine as shown by the decrease in %HF and the increase in beta.(ABSTRACT TRUNCATED AT 250 WORDS)

A Measure of Heart Rate Variability is Sensitive to Orthostatic Challenge in Women with Chronic Fatigue Syndrome

2003 ◽  
Vol 228 (2) ◽  
pp. 167-174 ◽  
Author(s):  
Yoshiharu Yamamoto ◽  
John J. Lamanca ◽  
Benjamin H. Natelson
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Chronic Fatigue Syndrome ◽  
Coarse Graining ◽  
Chronic Fatigue ◽  
Specific Response ◽  
Spectral Exponent ◽  
Fatigue Syndrome ◽  
Head Up Tilt ◽  
The Difference

The use of symptoms generated by head up tilt (HUT) is not a useful tool in identifying chronic fatigue syndrome (CFS). We investigated whether heart rate variability (HRV) assessed early during HUT might be useful. A sample of 46 female subjects (24 with CFS and 22 sedentary, age-matched healthy controls; CON) who had exhibited no difference in time to syncope during tilt was examined for HRV responses to 10 min of 70° HUT after 5 min of baseline in the supine position. HRV data were analyzed by the method of coarse graining spectral analysis. Variables compared between groups included mean and standard deviation (SDRRI) of RR intervals (RRI), amplitudes of low- (ALF; 0.04–0.15 Hz) and high-frequency (AHF; >0.15 Hz) harmonic as well as aperiodic, fractal (AFR; 1/fβ) spectral components, the spectral exponent β, and the difference in these values between baseline and HUT for each subject. In the supine baseline, only mean RRI was significantly (P< 0.01) lower in CFS than in CON. During HUT, however, mean RRI (P < 0.01), SDRRI, (P < 0.01), AHF (P < 0.05), and AFR (P < 0.01) were significantly lower in CFS than in CON. When the difference in values between baseline and HUT for each subject was examined, only the difference for AFR (ΔAFR) was significantly (P < 0.01) lower in CFS than in CON, suggesting that AFR is a disease-specific response of HRV to HUT. When a cut-off level was set to ΔAFR = –2.7 msec, the sensitivity and the specificity in differentiating CFS from controls were 90% and 72%, respectively. The data suggest that a decrease in aperiodic fractal component of HRV in response to HUT can be used to differentiate patients with CFS from CON.

scholarly journals Even slight movements disturb analysis of cardiovascular dynamics

1999 ◽  
Vol 277 (1) ◽  
pp. H261-H267 ◽  
Author(s):  
Jacques-Olivier Fortrat ◽  
Cédric Formet ◽  
Jean Frutoso ◽  
Claude Gharib
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Spectral Analysis ◽  
Low Frequency ◽  
Coarse Graining ◽  
Spectral Exponent ◽  
Spontaneous Movements ◽  
Frequency Components ◽  
Fractal Noise

We hypothesized that spontaneous movements (postural adjustments and ideomotion) disturb analysis of heart rate and blood pressure variability and could explain the discrepancy between studies. We measured R-R intervals and systolic blood pressure in nine healthy sitting subjects during three protocols: 1) no movement allowed, 2) movements allowed but not standing, 3) movements and standing allowed. Heart rate and blood pressure were not altered by movements. Movements with or without standing produced a twofold or greater increase of the overall variability of R-R intervals and of the low-frequency components of spectral analysis of heart rate variability. The spectral exponent β of heart rate variability (1.123 at rest) was changed by movements (1.364), and the percentage of fractal noise (79% at rest) was increased by standing (91%, coarse-graining spectral analysis). Spontaneous movements could induce a plateau in the correlation dimensions of heart rate variability, but they changed its nonlinear predictability. We suggest that future studies on short-term cardiovascular variability should control spontaneous movements.

Decreased fractal component of human heart rate variability during non-REM sleep

2001 ◽  
Vol 280 (1) ◽  
pp. H17-H21 ◽  
Author(s):  
Fumiharu Togo ◽  
Yoshiharu Yamamoto
Keyword(s):  
Heart Rate ◽  
Time Series ◽  
Heart Rate Variability ◽  
Rem Sleep ◽  
Healthy Subjects ◽  
Sleep Stage ◽  
Coarse Graining ◽  
Short Term ◽  
Waking And Sleep ◽  
The Brain

The physiological significance of the fractal component of short-term, spontaneous heart rate variability (HRV) in humans remains unclear. The aim of the present study was to gain further information about the respective fractal components by extracting them from HRV, blood pressure variability (BPV), and instantaneous lung volume (ILV) time series via coarse graining spectral analysis in nine healthy subjects during waking and sleep states. The results show that the contribution made by the fractal component to the total variance in the beat-to-beat R-R interval declined significantly as the depth of non-rapid eye movement (non-REM) sleep increased, that the ILV time series was largely periodic (i.e., nonfractal), and that BPV was unaffected by sleep stage. Finally, the fractal component of HRV during REM sleep was found to be quite similar to that seen during waking. These results suggest that mechanisms involving electroencephalographic desynchronization and/or conscious states of the brain are reflected in the fractal component of HRV.

Vagally Mediated Heart Rate Variability Promotes the Perception of Paradoxical Pain

2017 ◽  
Vol 31 (3) ◽  
pp. 134-144
Author(s):  
Raymonde Scheuren ◽  
Stefan Sütterlin ◽  
Fernand Anton
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Pain Sensitivity ◽  
Self Regulation ◽  
Noxious Stimulation ◽  
Dominant Hand ◽  
Resting Heart Rate ◽  
Sinus Arrhythmia ◽  
Thermal Grill Illusion ◽  
Resting Heart Rate Variability

Abstract. Self-regulation mechanisms are governed by prefrontal inhibitory processes and play a crucial role in the modulation of pain. In the present study the thermal grill paradigm was used to investigate the association of vagally mediated resting heart rate variability, a psychophysiological marker of trait self-regulatory capacity, with paradoxical pain sensations induced by non-noxious stimulation. This thermal grill illusion is only perceived by part of the tested individuals. The mechanisms underlying the observed interindividual differences in paradoxical pain sensitivity are largely unknown. During the experimental task, a temperature combination of 15 °C and 41 °C was set at the glass tubes of the thermal grill. The 52 healthy participants placed their dominant hand on the grill for a duration of one min. The magnitude of sensory and affective pain sensations perceived during stimulation was assessed with numerical rating scales. Before stimulation, a short-term electrocardiogram was recorded to compute vagally mediated heart rate variability at rest. Logistic regression analyses revealed that participants with higher vagal tone were significantly more likely to perceive the thermal grill illusion than subjects displaying lower resting heart rate variability. Paradoxical pain sensations were primarily predicted by normalized respiratory sinus arrhythmia. Our results confirm that the magnitude of vagally mediated resting heart rate variability is associated with the individual disposition to illusive pain perceptions. Since the latter is considered to be a marker of trait self-regulation ability, the present findings may corroborate and complement previous evidence for an impact of psychological characteristics on paradoxical pain sensitivity.

Regional Frontal Lobe Response Magnitudes During Affective Shifting Covary With Resting Heart Rate Variability in Healthy Volunteers

2016 ◽  
Vol 30 (4) ◽  
pp. 165-174 ◽  
Author(s):  
Ryan Smith ◽  
John J.B. Allen ◽  
Julian F. Thayer ◽  
Richard D. Lane
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Healthy Subjects ◽  
Emotional Reactivity ◽  
Bold Signal ◽  
Resting Heart Rate ◽  
Functional Magnetic Resonance ◽  
Absolute Value ◽  
Cardiac Vagal Control ◽  
Resting Heart Rate Variability

Abstract. We hypothesized that in healthy subjects differences in resting heart rate variability (rHRV) would be associated with differences in emotional reactivity within the medial visceromotor network (MVN). We also probed whether this MVN-rHRV relationship was diminished in depression. Eleven healthy adults and nine depressed subjects performed the emotional counting stroop task in alternating blocks of emotion and neutral words during functional magnetic resonance imaging (fMRI). The correlation between rHRV outside the scanner and BOLD signal reactivity (absolute value of change between adjacent blocks in the BOLD signal) was examined in specific MVN regions. Significant negative correlations were observed between rHRV and average BOLD shift magnitude (BSM) in several MVN regions in healthy subjects but not depressed subjects. This preliminary report provides novel evidence relating emotional reactivity in MVN regions to rHRV. It also provides preliminary suggestive evidence that depression may involve reduced interaction between the MVN and cardiac vagal control.

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