Heart rate at 4 s after the onset of exercise in endurance-trained men

2014 ◽  
Vol 92 (6) ◽  
pp. 476-480 ◽  
Author(s):  
Divanei Zaniqueli ◽  
Elis Aguiar Morra ◽  
Eduardo Miranda Dantas ◽  
Marcelo Perim Baldo ◽  
Luciana Carletti ◽  
...  
Keyword(s):  
Heart Rate ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Sinus Node ◽  
Low Frequency ◽  
Spectral Indices ◽  
High Frequency Band ◽  
Band Ratio ◽  
Endurance Runners ◽  
Vagal Influence

It has been suggested that the increase in heart rate (HR) at the onset of exercise is caused by vagal withdrawal. In fact, endurance runners show a lower HR in maximum aerobic tests. However, it is still unknown whether endurance runners have a lower HR at 4 s after the onset of exercise (4th-sec-HR). We sought to measure the HR at the onset of the 4 s exercise test (4-sET), clarifying its relationship to heart rate variability (HRV), spectral indices, and cardiac vagal index (CVI) in endurance runners (ER) and healthy untrained controls (CON). HR at 4th-sec-HR, CVI, and percent HR increase during exercise were analyzed in the 4-sET. High frequency spectrum (HF-nu), low frequency spectrum (LF-nu), and low frequency/high frequency band ratio (LF/HF) were analyzed from the HRV. ER showed a significantly higher HF, and both a lower LF and LF/HF ratio compared with the CON. ER presented a significantly lower 4th-sec-HR, although neither CVI nor HR increases during exercise were statistically different from the CON. In conclusion, ER presented a lower 4th-sec-HR secondary to increased vagal influence over the sinus node. CVI seems to be too weak to use for discriminating individuals with respect to the magnitude of HR vagal control.

Effect of Inhalation of 30% Nitrous Oxide on Spectral Components of Heart Rate Variability in Conscious man

1993 ◽  
Vol 85 (4) ◽  
pp. 389-392 ◽  
Author(s):  
D. C. Galletly ◽  
P. D. Tobin ◽  
B.J. Robinson ◽  
T. Corfiatis
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Low Frequency ◽  
Spectral Components ◽  
Frequency Components ◽  
The Mean ◽  
Frequency Power ◽  
High Frequency Spectrum

1. Periodicities in cardiac interbeat interval may be resolved into discrete frequency components by applying Fourier analysis to heart rate time series. Low-frequency components (<0.15 Hz) are believed to be under parasympathetic and sympathetic control, whereas a higher frequency component in phase with respiration is believed to be entirely parasympathetic. The ratio of the power in the low-/high-frequency spectrum gives an estimate of sympathetic/para-sympathetic balance. 2. This study examined, using heart rate variability spectral analysis, the cardiac autonomic effects of breathing 30% N2O in normal subjects. While supine, the inhalation of N2O caused a significant fall in high-frequency power and a rise in the low-/high-frequency spectrum. During air breathing, tilting caused a significant rise in the mean blood pressure, heart rate, low-frequency power and low-/high-frequency spectrum. During N2O breathing, tilting caused a rise in the heart rate and the mean blood pressure, but no significant alteration in the power of individual spectral components. During tilting, the heart rate, the low-frequency and low-/high-frequency spectrum were less when breathing N2O than when breathing air. 3. These observations are consistent with the effect of N2O being an enhanced sympathetic balance of sinoatrial control, with the primary effect being through reduced parasympathetic tone. Enhanced sympathetic dominance of heart rate variability was seen on standing while subjects breathed air, but this effect was blunted with N2O.

scholarly journals Sleep disordered breathing and autonomic function in overweight and obese children and adolescents

2016 ◽  
Vol 2 (4) ◽  
pp. 00038-2016 ◽  
Author(s):  
Annelies Van Eyck ◽  
Kim Van Hoorenbeeck ◽  
Benedicte Y. De Winter ◽  
Luc Van Gaal ◽  
Wilfried De Backer ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Frequency Band ◽  
High Frequency ◽  
Urinary Free Cortisol ◽  
High Frequency Band ◽  
Band Ratio ◽  
Rr Interval ◽  
Free Cortisol ◽  
Mean Heart Rate

Obstructive sleep apnoea (OSA), common in children with obesity, is associated with cardiovascular morbidity. Autonomic dysfunction has been suggested to be a key player in the development of these complications. We investigated the relationship between obesity, OSA and sympathetic activity in children.191 children with obesity were included and distributed into two groups: 131 controls and 60 with OSA. Beat-to-beat RR interval data were extracted from polysomnography for heart rate variability analysis. Urinary free cortisol levels were determined.Urinary free cortisol did not differ between groups and was not associated with OSA, independent of the level of obesity. Differences in heart rate variability measures were found: mean RR interval decreased with OSA, while low/high-frequency band ratio and mean heart rate increased with OSA. Heart rate variability measures correlated with OSA, independent of obesity parameters and age: oxygen desaturation index correlated with mean heart rate (r=0.19, p=0.009) and mean RR interval (r= −0.18, p=0.02), while high-frequency bands and low/high-frequency band ratio correlated with arterial oxygen saturation measured by pulse oximetry (SpO2) (r= −0.20, p=0.008 and r= −0.16, p=0.04) andSpO2nadir (r=0.23, p=0.003 and r= −0.19, p=0.02).These results suggest that sympathetic heart activity is increased in children with obesity and OSA. Measures of hypoxia were related to increased sympathetic tone, suggesting that intermittent hypoxia is involved in autonomic dysfunction.

scholarly journals The Influence ofNrf2on Cardiac Responses to Environmental Stressors

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Reuben Howden ◽  
Eva Gougian ◽  
Marcus Lawrence ◽  
Samantha Cividanes ◽  
Wesley Gladwell ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Therapeutic Strategies ◽  
Environmental Stressors ◽  
Total Power ◽  
Airborne Pollutants ◽  
Cardiac Responses

Nrf2protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role ofNrf2on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption ofNrf2would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures.Nrf2-/-andNrf2+/+mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P<0.001) and HF HRV (P<0.001) inNrf2-/-mice compared toNrf2+/+mice.Nrf2-/-mice tolerated hyperoxia significantly less thanNrf2+/+mice (~22 hrs;P<0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater inNrf2-/-compared toNrf2+/+mice (P<0.01). Results demonstrate thatNrf2deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

Preferential acceleration of heavy ions from thermal velocities

1968 ◽  
Vol 46 (10) ◽  
pp. S638-S641 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Frequency Spectrum ◽  
High Frequency ◽  
Heavy Ions ◽  
Crab Nebula ◽  
Low Frequency ◽  
High Frequency Waves ◽  
Hydromagnetic Waves ◽  
The Crab Nebula ◽  
Low Frequency Waves

The acceleration of ions from thermal velocities is analyzed to determine conditions under which heavy ions can be preferentially accelerated. Two accelerating mechanisms involving high-and low-frequency hydromagnetic waves respectively are considered. Preferential acceleration of heavy ions occurs for high-frequency waves if the frequency spectrum falls off faster than (frequency)−1. For the low-frequency waves heavy ions are less effectively accelerated than lighter ions. However, very heavy ions can be preferentially accelerated, the abundances of the very heavy ions being enhanced by a factor Ai over the thermal abundances. Acceleration of ions in the envelope of the Crab nebula is considered as an example.

scholarly journals Effect of Acupuncture on Heart Rate Variability: A Systematic Review

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Joanne W. Y. Chung ◽  
Vincent C. M. Yan ◽  
Hongwei Zhang
Keyword(s):  
Systematic Review ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Healthy Subjects ◽  
Keyword Search ◽  
Data Extraction ◽  
Meta Analysis ◽  
Low Frequency ◽  
Control Group

Aim.To summarize all relevant trials and critically evaluate the effect of acupuncture on heart rate variability (HRV).Method.This was a systematic review with meta-analysis. Keyword search was conducted in 7 databases for randomized controlled trials (RCTs). Data extraction and risk of bias were done.Results.Fourteen included studies showed a decreasing effect of acupuncture on low frequency (LF) and low frequency to high frequency ratio (LF/HF ratio) of HRV for nonhealthy subjects and on normalized low frequency (LF norm) for healthy subjects. The overall effect was in favour of the sham/control group for high frequency (HF) in nonhealthy subjects and for normalized high frequency (HF norm) in healthy subjects. Significant decreasing effect on HF and LF/HF ratio of HRV when acupuncture was performed on ST36 among healthy subjects and PC6 among both healthy and nonhealthy subjects, respectively.Discussion.This study partially supports the possible effect of acupuncture in modulating the LF of HRV in both healthy and nonhealthy subjects, while previous review reported that acupuncture did not have any convincing effect on HRV in healthy subjects. More published work is needed in this area to determine if HRV can be an indicator of the therapeutic effect of acupuncture.

Modulation of Neurocardiac Function by Oesophageal Stimulation in Humans

1997 ◽  
Vol 92 (2) ◽  
pp. 167-174 ◽  
Author(s):  
Gervais Tougas ◽  
Markad Kamath ◽  
Geena Watteel ◽  
Debbie Fitzpatrick ◽  
Ernest L. Fallen ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Power Spectrum ◽  
High Frequency ◽  
Low Frequency ◽  
Sensory Stimulation ◽  
Sensory Stimuli ◽  
Autonomic Reflexes ◽  
Low Frequency Power ◽  
Beat Heart

1. The heart and the oesophagus have similar sensory pathways, and sensations originating from the oesophagus are often difficult to differentiate from those of cardiac origin. We hypothesized that oesophageal sensory stimuli could alter neurocardiac function through autonomic reflexes elicited by these oesophageal stimuli. In the present study, we examined the neurocardiac response to oesophageal stimulation and the effects of electrical and mechanical oesophageal stimulation on the power spectrum of beat-to-beat heart rate variability in male volunteers. 2. In 14 healthy volunteers, beat-to-beat heart rate variability was compared at rest and during oesophageal stimulation, using either electrical (200 μs, 16 mA, 0.2 Hz) or mechanical (0.5 s, 14 ml, 0.2 Hz) stimuli. The power spectrum of beat-to-beat heart rate variability was obtained and its low- and high-frequency components were determined. 3. Distal oesophageal stimulation decreased heart rate slightly (both electrical and mechanical) (P < 0.005), and markedly altered heart rate variability (P < 0.001). Both electrical and mechanical oesophageal stimulation increased the absolute and normalized area of the high-frequency band within the power spectrum (P < 0.001), while simultaneously decreasing the low-frequency power (P < 0.005). 4. In humans, oesophageal stimulation, whether electrical or mechanical, appears to amplify respiratory-driven cardiac vagoafferent modulation while decreasing sympathetic modulation. The technique provides access to vagoafferent fibres and thus may yield useful information on the autonomic effects of visceral or oesophageal sensory stimulation.

Sleep Stage Assessment Using Power Spectral Indices of Heart Rate Variability With a Simple Algorithm

2012 ◽  
Vol 15 (3) ◽  
pp. 264-272 ◽  
Author(s):  
Keiko Tanida ◽  
Masashi Shibata ◽  
Margaret M. Heitkemper
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Sleep Stage ◽  
Sleep Onset ◽  
Low Frequency ◽  
Simple Algorithm ◽  
Sleep Stages ◽  
Spectral Indices ◽  
Current Form ◽  
Power Spectral

Clinical researchers do not typically assess sleep with polysomnography (PSG) but rather with observation. However, methods relying on observation have limited reliability and are not suitable for assessing sleep depth and cycles. The purpose of this methodological study was to compare a sleep analysis method based on power spectral indices of heart rate variability (HRV) data to PSG. PSG and electrocardiography data were collected synchronously from 10 healthy women (ages 20–61 years) over 23 nights in a laboratory setting. HRV was analyzed for each 60-s epoch and calculated at 3 frequency band powers (very low frequency [VLF]-hi: 0.016–0.04 Hz; low frequency [LF]: 0.04–0.15 Hz; and high frequency [HF]: 0.15–0.4 Hz). Using HF/(VLF-hi + LF + HF) value, VLF-hi, and heart rate (HR) as indices, an algorithm to categorize sleep into 3 states (shallow sleep corresponding to Stages 1 & 2, deep sleep corresponding to Stages 3 & 4, and rapid eye movement [REM] sleep) was created. Movement epochs and time of sleep onset and wake-up were determined using VLF-hi and HR. The minute-by-minute agreement rate with the sleep stages as identified by PSG and HRV data ranged from 32 to 72% with an average of 56%. Longer wake after sleep onset (WASO) resulted in lower agreement rates. The mean differences between the 2 methods were 2 min for the time of sleep onset and 6 min for the time of wake-up. These results indicate that distinguishing WASO from shallow sleep segments is difficult using this HRV method. The algorithm's usefulness is thus limited in its current form, and it requires additional modification.

Age dependency of cardiovascular autonomic responses to head-up tilt in healthy subjects

2004 ◽  
Vol 96 (6) ◽  
pp. 2333-2340 ◽  
Author(s):  
Tomi Laitinen ◽  
Leo Niskanen ◽  
Ghislaine Geelen ◽  
Esko Länsimies ◽  
Juha Hartikainen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
High Frequency ◽  
Healthy Subjects ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Upright Position ◽  
Vascular Responses ◽  
Autonomic Responses ◽  
Head Up Tilt

In elderly subjects, heart rate responses to postural change are attenuated, whereas their vascular responses are augmented. Altered strategy in maintaining blood pressure homeostasis during upright position may result from various cardiovascular changes, including age-related cardiovascular autonomic dysfunction. This exploratory study was conducted to evaluate impact of age on cardiovascular autonomic responses to head-up tilt (HUT) in healthy subjects covering a wide age range. The study population consisted of 63 healthy, normal-weight, nonsmoking subjects aged 23–77 yr. Five-minute electrocardiogram and finger blood pressure recordings were performed in the supine position and in the upright position 5 min after 70° HUT. Stroke volume was assessed from noninvasive blood pressure signals by the arterial pulse contour method. Heart rate variability (HRV) and systolic blood pressure variability (SBPV) were analyzed by using spectral analysis, and baroreflex sensitivity (BRS) was assessed by using sequence and cross-spectral methods. Cardiovascular autonomic activation during HUT consisted of decreases in HRV and BRS and an increase in SBPV. These changes became attenuated with aging. Age correlated significantly with amplitude of HUT-stimulated response of the high-frequency component ( r = -0.61, P < 0.001) and the ratio of low-frequency to high-frequency power of HRV ( r = -0.31, P < 0.05) and indexes of BRS (local BRS: r = -0.62, P < 0.001; cross-spectral baroreflex sensitivity in the low-frequency range: r = -0.38, P < 0.01). Blood pressure in the upright position was maintained well irrespective of age. However, the HUT-induced increase in heart rate was more pronounced in the younger subjects, whereas the increase in peripheral resistance was predominantly observed in the older subjects. Thus it is likely that whereas the dynamic capacity of cardiac autonomic regulation decreases, vascular responses related to vasoactive mechanisms and vascular sympathetic regulation become augmented with increasing age.

Effect of fingolimod on cardiac autonomic regulation in patients with multiple sclerosis

2015 ◽  
Vol 22 (8) ◽  
pp. 1080-1085 ◽  
Author(s):  
Sakari Simula ◽  
Tomi Laitinen ◽  
Tiina M Laitinen ◽  
Tuula Tarkiainen ◽  
Päivi Hartikainen ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Frequency Ratio ◽  
Low Frequency ◽  
Autonomic Regulation ◽  
Rr Interval ◽  
Cardiac Autonomic Regulation ◽  
Multiple Sclerosis Patients

Background: Fingolimod modulates sphingosine-1-phosphate receptors that are also found in cardiovascular tissue. Objective: To investigate the effects of fingolimod on cardiac autonomic regulation prospectively. Methods: Twenty-seven relapsing–remitting multiple sclerosis patients underwent 24-hour electrocardiogram recording before, at the first day of fingolimod treatment (1d) and after three months of continuous dosing (3mo). The time interval between two consecutive R-peaks (RR-interval) was measured. Cardiac autonomic regulation was assessed by the various parameters of heart rate variability. Parasympathetic stimulation prolongs the RR-interval and increases heart rate variability while the effects of sympathetic stimulation are mainly the opposite. The low frequency/high frequency ratio reflects sympathovagal balance. Results: From baseline to 1d, a prolongation of the RR-interval ( P<0.001), an increase in the values of various heart rate variability parameters ( P<0.05 to P<0.001) and a decrease in the low frequency/high frequency ratio ( P<0.05) were demonstrated. At 3mo, although the RR-interval remained longer ( P<0.01), the values of various heart rate variability parameters were lower ( P<0.01 to P<0.001) as compared to baseline. At 3mo, the low frequency/high frequency ratio ( P<0.05) was higher in men than in women although no such difference was found at baseline or at 1d. Conclusions: After an initial increase in parasympathetic regulation, continuous fingolimod dosing shifts cardiac autonomic regulation towards sympathetic predominance, especially in men. Careful follow-up of fingolimod-treated relapsing–remitting multiple sclerosis patients is warranted as sympathetic predominance associates generally with impaired outcome. ClinicalTrials.cov: NCT01704183

Abstract 4669: Does Long-QT Syndrome Involve the Sinus Node?

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Vladimir Shusterman ◽  
Jan Nemec ◽  
Marie Buncova ◽  
Bruce Winter ◽  
Win-Kuang Shen ◽  
...  
Keyword(s):  
Heart Rate ◽  
Long Qt Syndrome ◽  
High Frequency ◽  
Cardiac Rhythm ◽  
Sinus Node ◽  
List Type ◽  
High Frequency Power ◽  
Long Qt ◽  
Qt Syndrome ◽  
Frequency Power

Background: The hallmark of Long QT Syndrome (LQTS) is a prolongation of the ventricular electrical action potential caused by mutations involving key cardiac ion channels on the surface membrane of ventricular myocytes. Different mutations are associated with specific modes of arrhythmia initiation and distinct changes in cardiac rhythm prior to these events. We hypothesized that some LQTS-causing mutations might involve the sinus node, leading to aberrations in cardiac rhythm. To test this hypothesis, we examined the features of cardiac rhythm in 23 genotyped patients with LQTS and 14 matched controls (C) using Holter ECG data (6hrs). Methods: QRS-complexes were identified using custom software and verified by an experienced ECG reader; series of sinus beats were extracted and gaps in time series were linearly interpolated. The mean, max, and min heart rate (HR), the time (SD, SDNN, SDANN, RMSSD, pNN50) and frequency-domain (Total (TP), Very low (VLF), Low (LF), High (HF) frequency powers, and LF/HF) indices of heart rate variability (HRV) were calculated in each 5-min interval and over the entire recording. The short-long-short irregularity was examined using the novel multiscale rhythmogenetic analysis (MRA), which quantifies changes in the HRV indices during the transition from one time-scale window to another. Results: The maximum heart rate was slower in LQTS than in C (101±13 and 119±19bpm, p=0.001). The high-frequency power (HF) was lower in LQTS than in C (80±76 and 113±58ms 2 , p<0.05). However, the short-term irregularity (quantified by the difference in RMSSD between the 75ms and 2000ms time scales) was 4 times greater in LQTS compared to C (p=0.003). Inclusion or exclusion of two patents who were on β-blockers did not change the results. Conclusions: LQTS is associated with specific changes in cardiac rhythm, including: diminished acceleration capacity, decreased high-frequency power, and enhanced short-long-short irregularity. This suggests that LQTS involves channel modifications in the sinus node, which might contribute to arrhythmogenesis. Rhythm characterization in genetic sub-types of LQTS might improve arrhythmia risk stratification in this heterogeneous patient population.

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