Impact of acute hypoxia on heart rate and blood pressure variability in conscious dogs

2000 ◽  
Vol 279 (5) ◽  
pp. H2344-H2349 ◽  
Author(s):  
Fumihiko Yasuma ◽  
Jun-Ichiro Hayano
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Pressure ◽  
Minute Ventilation ◽  
Low Frequency ◽  
Frequency Component ◽  
Conscious Dogs ◽  
High Frequency Component ◽  
Progressive Hypoxia ◽  
Cardiovascular Variables

To examine whether the impacts of hypoxia on autonomic regulations involve the phasic modulations as well as tonic controls of cardiovascular variables, heart rate, blood pressure, and their variability during isocapnic progressive hypoxia were analyzed in trained conscious dogs prepared with a permanent tracheostomy and an implanted blood pressure telemetry unit. Data were obtained at baseline and when minute ventilation (V˙i) first reached 10 (V˙i10), 15 (V˙i15), and 20 (V˙i20) l/min during hypoxia. Time-dependent changes in the amplitudes of the high-frequency component of the R-R interval (RRIHF) and the low-frequency component of mean arterial pressure (MAPLF) were analyzed by complex demodulation. In a total of 47 progressive hypoxic runs in three dogs, RRIHF decreased atV˙i15 and V˙i20 and MAPLF increased at V˙i10 and V˙i15 but not atV˙i20, whereas heart rate and arterial pressure increased progressively with advancing hypoxia. We conclude that the autonomic responses to isocapnic progressive hypoxia involve tonic controls and phasic modulations of cardiovascular variables; the latter may be characterized by a progressive reduction in respiratory vagal modulation of heart rate and a transient augmentation in low-frequency sympathetic modulation of blood pressure.

Augmentation of respiratory sinus arrhythmia in response to progressive hypercapnia in conscious dogs

2001 ◽  
Vol 280 (5) ◽  
pp. H2336-H2341 ◽  
Author(s):  
Fumihiko Yasuma ◽  
Jun-Ichiro Hayano
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Respiratory Sinus Arrhythmia ◽  
Physiological Response ◽  
Minute Ventilation ◽  
Control Level ◽  
Conscious Dogs ◽  
Sinus Arrhythmia ◽  
Arterial Blood

Respiratory sinus arrhythmia (RSA) may serve to enhance pulmonary gas exchange efficiency by matching pulmonary blood flow with lung volume within each respiratory cycle. We examined the hypothesis that RSA is augmented as an active physiological response to hypercapnia. We measured electrocardiograms and arterial blood pressure during progressive hypercapnia in conscious dogs that were prepared with a permanent tracheostomy and an implanted blood pressure telemetry unit. The intensity of RSA was assessed continuously as the amplitude of respiratory fluctuation of heart rate using complex demodulation. In a total of 39 runs of hypercapnia in 3 dogs, RSA increased by 38 and 43% of the control level when minute ventilation reached 10 and 15 l/min, respectively ( P < 0.0001 for both), and heart rate and mean arterial pressure showed no significant change. The increases in RSA were significant even after adjustment for the effects of increased tidal volume, respiratory rate, and respiratory fluctuation of arterial blood pressure ( P < 0.001). These observations indicate that increased RSA during hypercapnia is not the consequence of altered autonomic balance or respiratory patterns and support the hypothesis that RSA is augmented as an active physiological response to hypercapnia.

scholarly journals Heart Rate Variability Duration: Expanding the Ability of Wearable Technology to Improve Outpatient Monitoring?

2021 ◽  
Vol 12 ◽  
Author(s):  
David C. Sheridan ◽  
Karyssa N. Domingo ◽  
Ryan Dehart ◽  
Steven D. Baker
Keyword(s):  
Mental Health ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Windows ◽  
Low Frequency ◽  
Frequency Component ◽  
Wearable Technology ◽  
Mental Health Research ◽  
High Frequency Component ◽  
Frequency Domains

Heart rate variability (HRV) evaluates beat-to-beat interval (BBI) differences and is a suggested marker of the autonomic nervous system with diagnostic/monitoring capabilities in mental health; especially parasympathetic measures. The standard duration for short-term HRV analysis ranges from 24 h down to 5-min. However, wearable technology, mainly wrist devices, have large amounts of motion at times resulting in need for shorter duration of monitoring. The objective of this study was to evaluate the correlation between 1 and 5 min segments of continuous HRV data collected simultaneously on the same patient. Subjects wore a patch electrocardiograph (Cardea Solo, Inc.) over a 1–7 day period. For every consecutive hour the patch was worn, we selected a 5-min, artifact-free electrocardiogram segment. HRV metric calculation was performed to the entire 5-min segment and the first 1-min from this same 5-min segment. There were 492 h of electrocardiogram data collected allowing calculation of 492 5 min and 1 min segments. 1 min segments of data showed good correlation to 5 min segments in both time and frequency domains: root mean square of successive difference (RMSSD) (R = 0.92), high frequency component (HF) (R = 0.90), low frequency component (LF) (R = 0.71), and standard deviation of NN intervals (SDNN) (R = 0.63). Mental health research focused on parasympathetic HRV metrics, HF and RMSSD, may be accomplished through smaller time windows of recording, making wearable technology possible for monitoring.

Phenotypic screening for heart rate variability in the mouse

2000 ◽  
Vol 279 (2) ◽  
pp. H733-H740 ◽  
Author(s):  
Josef Gehrmann ◽  
Peter E. Hammer ◽  
Colin T. Maguire ◽  
Hiroko Wakimoto ◽  
John K. Triedman ◽  
...  
Keyword(s):  
Heart Rate ◽  
Molecular Mechanisms ◽  
Parasympathetic Nervous System ◽  
Low Frequency ◽  
Gene Mutations ◽  
Frequency Component ◽  
High Frequency Component ◽  
Mouse Strains ◽  
Phenotypic Screening ◽  
Sensitivity Testing

We developed a technology for heart rate (HR) variability (HRV) analysis in the mouse for characterization of HR dynamics, modulated by vagal and sympathetic activity. The mouse is the principal animal model for studying biological processes. Mouse strains are now available harboring gene mutations providing fundamental insights into molecular mechanisms underlying cardiac electrical diseases. Future progress depends on enhanced understanding of these fundamental mechanisms and the implementation of methods for the functional analysis of mouse cardiovascular physiology. By telemetric techniques, standard time and frequency-domain measures of HRV were computed with and without autonomic blockade, and baroreflex sensitivity testing was performed. HR modulation in the high-frequency component is predominantly mediated by the parasympathetic nervous system, whereas the low-frequency component is under the influence of both the parasympathetic and sympathetic systems. The presented technology and protocol allow for assessment of autonomic regulation of the murine HR. Phenotypic screening for HR regulation in mice will further enhance the value of the mouse as a model of heritable electrophysiological human disease.

scholarly journals Changes in Heart Rate Variability of Depressed Patients after Electroconvulsive Therapy

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Erica B. Royster ◽  
Lisa M. Trimble ◽  
George Cotsonis ◽  
Brian Schmotzer ◽  
Amita Manatunga ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Depressive Symptoms ◽  
Electroconvulsive Therapy ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Acute Changes ◽  
The Impact

Objective. As few, small studies have examined the impact of electroconvulsive therapy (ECT) upon the heart rate variability of patients with major depressive disorder (MDD), we sought to confirm whether ECT-associated improvement in depressive symptoms would be associated with increases in HRV linear and nonlinear parameters. Methods. After providing consent, depressed study participants (n=21) completed the Beck Depression Index (BDI), and 15-minute Holter monitor recordings, prior to their 1st and 6th ECT treatments. Holter recordings were analyzed for certain HRV indices: root mean square of successive differences (RMSSD), low-frequency component (LF)/high-frequency component (HF) and short-(SD1) versus long-term (SD2) HRV ratios. Results. There were no significant differences in the HRV indices of RMSDD, LF/HF, and SD1/SD2 between the patients who responded, and those who did not, to ECT. Conclusion. In the short term, there appear to be no significant improvement in HRV in ECT-treated patients whose depressive symptoms respond versus those who do not. Future studies will reveal whether diminished depressive symptoms with ECT are reliably associated with improved sympathetic/parasympathetic balance over the long-term, and whether acute changes in sympathetic/parasympathetic balance predict improved mental- and cardiac-related outcomes.

scholarly journals Stress Recovery Effects of High- and Low-Frequency Amplified Music on Heart Rate Variability

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yoshie Nakajima ◽  
Naofumi Tanaka ◽  
Tatsuya Mima ◽  
Shin-Ichi Izumi
Keyword(s):  
Heart Rate ◽  
White Noise ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Stress Recovery ◽  
Recovery Ratio ◽  
Autonomic Responses ◽  
Frequency Components

Sounds can induce autonomic responses in listeners. However, the modulatory effect of specific frequency components of music is not fully understood. Here, we examined the role of the frequency component of music on autonomic responses. Specifically, we presented music that had been amplified in the high- or low-frequency domains. Twelve healthy women listened to white noise, a stress-inducing noise, and then one of three versions of a piece of music: original, low-, or high-frequency amplified. To measure autonomic response, we calculated the high-frequency normalized unit (HFnu), low-frequency normalized unit, and the LF/HF ratio from the heart rate using electrocardiography. We defined the stress recovery ratio as the value obtained after participants listened to music following scratching noise, normalized by the value obtained after participants listened to white noise after the stress noise, in terms of the HFnu, low-frequency normalized unit, LF/HF ratio, and heart rate. Results indicated that high-frequency amplified music had the highest HFnu of the three versions. The stress recovery ratio of HFnu under the high-frequency amplified stimulus was significantly larger than that under the low-frequency stimulus. Our results suggest that the high-frequency component of music plays a greater role in stress relief than low-frequency components.

Effect of Head-Down Tilt on Cardiovascular Control in Healthy Subjects: A Spectral Analytic Approach

1995 ◽  
Vol 88 (1) ◽  
pp. 87-93 ◽  
Author(s):  
F. Weise ◽  
G. M. London ◽  
A. P. Guerin ◽  
B. M. Pannier ◽  
J.-L. Elghozi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Time Series ◽  
Systolic Blood Pressure ◽  
Vascular Resistance ◽  
High Frequency ◽  
Area Under The Curve ◽  
Low Frequency ◽  
Frequency Component ◽  
Forearm Vascular Resistance

1. The purpose of this investigation was to determine non-invasively the changes in autonomic cardiovascular control observed in normal subjects submitted to acute cardiopulmonary blood volume expansion by 100° head-down tilt. The effect of head-down tilt on finger blood pressure and heart rate fluctuations was studied by means of power spectral analysis in 12 healthy men. 2. Amplitude spectra of heart rate and blood pressure rhythmicity were estimated at the low-frequency (60–140 mHz, 10-s rhythm) and high-frequency (area under the curve at mean respiration rate ± 50 mHz) component. Transfer gain and phase were calculated between systolic blood pressure and heart rate. Forearm vascular resistance was estimated to validate the head-down procedure. 3. Forearm vascular resistance decreased significantly from 19.82 (16.34–26.46) mmHg ml−1 min 100 ml to 18.05 (13.69–22.88) mmHg ml−1 min 100 ml (P < 0.01) during head-down tilt (values are medians and 25 and 75 percentiles). The overall variability (total area under the curve of the spectrum from 20 to 500 mHz) of blood pressure and heart rate time series was consistently reduced with head-down tilt. 4. The spectral pattern of systolic blood pressure showed a diminution of the absolute and relative low-frequency component during head-down tilt: absolute log-transformed values, 2.86 (2.80–2.94) mmHg/Hz1/2 versus 2.77 (2.72–2.82) mmHg/Hz1/2 (P < 0.05); relative values, 35% (32–37%) versus 32% (29–32%) (P < 0.05). In heart rate spectra only the absolute low-frequency component decreased. There was no change in the high-frequency component in all time series or in the transfer gain and phase during head-down tilt. 5. It is concluded that head-down tilt is a simple manoeuvre to diminish the 10-s rhythm in systolic blood pressure, which may reflect the reduced sympathetic vasomotor control after cardiopulmonary baroreceptor loading.

Measurement of the Low-frequency Component of Blood Pressure Variability Can Assist the Interpretation of Heart Rate Variability Data

2003 ◽  
Vol 99 (1) ◽  
pp. 237-237
Author(s):  
Charles W. Hogue ◽  
Pekka Talke ◽  
Phyllis K. Stein ◽  
Peter P. Domitrovich ◽  
Daniel I. Sessler
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Blood Pressure Variability ◽  
Low Frequency ◽  
Frequency Component ◽  
Variability Data

scholarly journals Assessment of autonomic function by long-term heart rate variability: beyond the classical framework of LF and HF measurements

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Junichiro Hayano ◽  
Emi Yuda
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Autonomic Function ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Short Term ◽  
Heart Rate Turbulence ◽  
Free Running

AbstractIn the assessment of autonomic function by heart rate variability (HRV), the framework that the power of high-frequency component or its surrogate indices reflects parasympathetic activity, while the power of low-frequency component or LF/HF reflects sympathetic activity has been used as the theoretical basis for the interpretation of HRV. Although this classical framework has contributed greatly to the widespread use of HRV for the assessment of autonomic function, it was obtained from studies of short-term HRV (typically 5‑10 min) under tightly controlled conditions. If it is applied to long-term HRV (typically 24 h) under free-running conditions in daily life, erroneous conclusions could be drawn. Also, long-term HRV could contain untapped useful information that is not revealed in the classical framework. In this review, we discuss the limitations of the classical framework and present studies that extracted autonomic function indicators and other useful biomedical information from long-term HRV using novel approaches beyond the classical framework. Those methods include non-Gaussianity index, HRV sleep index, heart rate turbulence, and the frequency and amplitude of cyclic variation of heart rate.

Yoga-Based Guided Relaxation Reduces Sympathetic Activity Judged from Baseline Levels

2002 ◽  
Vol 90 (2) ◽  
pp. 487-494 ◽  
Author(s):  
R. P. Vempati ◽  
Shirley Telles
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Sympathetic Activity ◽  
Low Frequency ◽  
Frequency Component ◽  
High Frequency Component ◽  
Before And After ◽  
Baseline Levels ◽  
Guided Relaxation ◽  
Heart Rate Variability Spectrum

35 male volunteers whose ages ranged from 20 to 46 years were studied in two sessions of yoga-based guided relaxation and supine rest. Assessments of autonomic variables were made for 15 subjects, before, during, and after the practices, whereas oxygen consumption and breath volume were recorded for 25 subjects before and after both types of relaxation. A significant decrease in oxygen consumption and increase in breath volume were recorded after guided relaxation (paired t test). There were comparable reductions in heart rate and skin conductance during both types of relaxation. During guided relaxation the power of the low frequency component of the heart-rate variability spectrum reduced, whereas the power of the high frequency component increased, suggesting reduced sympathetic activity. Also, subjects with a baseline ratio of LF/HF >0.5 showed a significant decrease in the ratio after guided relaxation, while subjects with a ratio ≤0.5 at baseline showed no such change. The results suggest that sympathetic activity decreased after guided relaxation based on yoga, depending on the baseline levels.

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