Phase response of the spectral coherence function between heart rate variability and ventricular repolarization duration in normal subjects

2002 ◽  
Author(s):  
P.R.B. Barbosa ◽  
J. Barbosa-Filho ◽  
I. Cordovil ◽  
A.B. Medeiros ◽  
J. Nadal
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Coherence Function ◽  
Normal Subjects ◽  
Ventricular Repolarization ◽  
Phase Response ◽  
Spectral Coherence

Aging and spectral characteristics of the nonharmonic component of 24-h heart rate variability

1999 ◽  
Vol 276 (6) ◽  
pp. R1724-R1731 ◽  
Author(s):  
Seiichiro Sakata ◽  
Junichiro Hayano ◽  
Seiji Mukai ◽  
Akiyoshi Okada ◽  
Takao Fujinami
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Power Law ◽  
Daily Life ◽  
Spectral Characteristics ◽  
Normal Subjects ◽  
Break Point ◽  
Total Power ◽  
Interindividual Difference ◽  
Analysis Of Dynamics

To examine whether heart rate variability (HRV) during daily life shows power law behavior independently of age and interindividual difference in the total power, log-log scaled coarse-graining spectra of the nonharmonic component of 24-h HRV were studied in 62 healthy men (age 21–79 yr). The spectra declined with increasing frequency in all subjects, but they appeared as broken lines slightly bending downward, particularly in young subjects with a large total power. Regression of the spectrum by a broken line with a single break point revealed that the spectral exponent (β) was greater in the region below than above the break point (1.63 ± 0.23 vs. 0.96 ± 0.21, P < 0.001). The break point frequency increased with age ( r = 0.51, P < 0.001) and β correlated with age negatively below the break point ( r = 0.39) and positively above the break point ( r = 0.70). The contribution to interindividual difference in total power was greater from the differences in the power spectral density at frequencies closer to both ends of the frequency axis and minimal from that at −3.25 log(Hz), suggesting hingelike movement of the spectral shape at this frequency with the difference in total power. These characteristics of the 24-h HRV spectrum were simulated by an artificial signal generated by adding two noises with different β values. Given that the power law assumption is fundamental to the analysis of dynamics through the log-log scaled spectrum, our observations are substantial for physiological and clinical studies of the heartbeat dynamic during daily life and suggest that the nonharmonic component of HRV in normal subjects during daily life may include at least two 1/ f β fluctuations that differ in dynamics and age dependency.

Assessment and clinical relevance of the dynamic parameters of ventricular repolarization in patients with grade I left ventricular diastolic dysfunction

2019 ◽  
Vol 97 (6) ◽  
pp. 577-580
Author(s):  
Antoinette Oliveira Blackman ◽  
José Sobral Neto ◽  
Melchior Luiz Lima ◽  
Tânia Maria Andrade Rodrigues ◽  
Otoni Moreira Gomes
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Diastolic Dysfunction ◽  
Qt Dispersion ◽  
Left Ventricular Diastolic Dysfunction ◽  
Left Ventricular ◽  
Ventricular Repolarization ◽  
Premature Ventricular Complex ◽  
Increased Risk ◽  
Ventricular Diastolic Dysfunction

Imbalance in ventricular repolarization parameters are related to increased risk of severe arrhythmia and sudden cardiac death. There is limited research regarding markers to detect patients at risk in this early stage. We aimed to assess the influence of grade I left ventricular diastolic dysfunction on repolarization parameters in asymptomatic patients. Ambulatory patients with grade I left ventricular diastolic dysfunction were studied and compared with a control group. We assessed the QT dispersion circadian variation, heart rate variability in the time and frequency domains, and dynamics of QT using a 12-lead Holter. In the diastolic dysfunction group, 8 (30%) patients had QT dispersion > 80 ms. One (3.8%) patient presented premature ventricular complex > 10/h. The comparison between the 2 groups showed that the difference between the standard deviation of normal-to-normal intervals and low frequency power in both groups was statistically significant. We therefore conclude that increased parameters of ventricular repolarization and depressed heart rate variability reflect an imbalance in autonomic responses in patients with grade I left ventricular diastolic dysfunction without cardiovascular symptoms, enabling the identification of patients that are at a higher risk for cardiovascular events.

Effects of acupuncture on heart rate variability in normal subjects under fatigue and non-fatigue state

2005 ◽  
Vol 94 (5-6) ◽  
pp. 633-640 ◽  
Author(s):  
Zengyong Li ◽  
Chengtao Wang ◽  
Arthur F. T. Mak ◽  
Daniel H. K. Chow
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Normal Subjects

Low-frequency heart rate variability: reproducibility in cardiac transplant recipients and normal subjects

2000 ◽  
Vol 100 (1) ◽  
pp. 43-46 ◽  
Author(s):  
S. W. LORD ◽  
R. R. SENIOR ◽  
M. DAS ◽  
A. M. WHITTAM ◽  
A. MURRAY ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Significant Variation ◽  
Low Frequency ◽  
Normal Subjects ◽  
Cardiac Transplant ◽  
Transplant Recipients ◽  
Late Afternoon ◽  
Early Afternoon ◽  
Nervous Influence

Heart rate variability is a measure of autonomic nervous influence on the heart. It has been suggested that it could be used to detect autonomic reinnervation to the transplanted heart, but the reproducibility of the measurement is unknown. In the present study, 21 cardiac transplant recipients and 21 normal subjects were recruited. Three measurements of heart rate variability were performed during the day: in the morning, in the early afternoon and in the late afternoon. These tests were then repeated 1 week later and then again 1 week after that, making nine tests in all. The within-subject S.D. was 0.49 log units in normal subjects and 0.79 log units in transplant recipients. In both cases, this is about 15% of the population range. There was significant variation in heart rate variability between different times of day in both groups, and from day to day in transplant recipients. It was concluded that the reproducibility of measurements of heart rate variability is low, and that differences between measurements performed at different times of day should be interpreted with caution.

Fractal Component of Variability of Heart Rate and Systolic Blood Pressure in Congestive Heart Failure

1997 ◽  
Vol 92 (6) ◽  
pp. 543-550 ◽  
Author(s):  
Gary C. Butler ◽  
Shin-Ichi Ando ◽  
John S. Floras
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Systolic Blood Pressure ◽  
Spectral Power ◽  
Normal Subjects ◽  
Total Spectral Power ◽  
Systolic Blood Pressure Variability ◽  
Harmonic Components

1. There is a substantial non-harmonic or fractal component to the variability of both heart rate and blood pressure in normal subjects. Heart rate is the more complex of these two signals, with respect to the slope, β, of the 1/fβ relationship. In congestive heart failure, heart rate spectral power is attenuated, but the fractal and harmonic components of heart rate and systolic blood pressure variability have not been characterized. 2. Two groups, each comprising 20 men, were studied during 15 min of supine rest and spontaneous respiration: one with functional class II—IV heart failure (age 52 ± 2 years; mean ± SEM) and a second group of healthy men (age 46 ± 2 years). 3. Total spectral power for heart rate was significantly reduced in heart failure (P < 0.02), whereas total spectral power for systolic blood pressure was similar in the two groups. In both heart failure and normal subjects, 65–80% of total spectral power in these two signals displayed fractal characteristics. 4. In heart failure, the slope of the 1/fβ relationship for heart rate was significantly steeper than in normal subjects (1.40 ± 0.08 compared with 1.14 ± 0.05; P < 0.05), indicating reduced complexity of the fractal component of heart rate variability. There was no significant difference in the 1/fβ slope for systolic blood pressure variability between these two groups, but the blood pressure signals were less complex than heart rate variations in both heart failure (2.31 ± 0.15; P < 0.006) and normal subjects (2.47 ± 0.15; P < 0.0001). 5. Parasympathetic nervous system activity, as estimated from heart rate variability was reduced (P < 0.01) in patients with heart failure, whereas trends towards increased sympathetic nervous system activity and decreased non-harmonic power were not significant. 6. The non-harmonic components of cardiac frequency are reduced in heart failure. Non-harmonic power is not attenuated, but the complexity of the heart rate signal is less than in subjects with normal ventricular function. A reduction in parasympathetic modulation appears to contribute to this loss of complexity of heart rate. Consequently, the heart rate signal comes to resemble that of blood pressure. In contrast, the variability and complexity of the systolic blood pressure signal is similar in heart failure and normal subjects. This reduced complexity of heart rate variability may have adverse implications for patients with heart failure.

scholarly journals Recovery of Heart Rate Variability and Ventricular Repolarization Indices Following Exercise

2012 ◽  
Vol 17 (4) ◽  
pp. 349-360 ◽  
Author(s):  
Marc K. Lahiri ◽  
Alexandru Chicos ◽  
Dan Bergner ◽  
Jason Ng ◽  
Smirti Banthia ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Ventricular Repolarization

Determinants of heart rate variability in obstructive sleep apnea syndrome during wakefulness and sleep

2005 ◽  
Vol 288 (3) ◽  
pp. H1103-H1112 ◽  
Author(s):  
J. A. Jo ◽  
A. Blasi ◽  
E. Valladares ◽  
R. Juarez ◽  
A. Baydur ◽  
...  
Keyword(s):  
Heart Rate ◽  
Obstructive Sleep Apnea ◽  
Heart Rate Variability ◽  
Sleep Apnea ◽  
Obstructive Sleep Apnea Syndrome ◽  
Sleep Apnea Syndrome ◽  
Normal Subjects ◽  
Sinus Arrhythmia ◽  
Obstructive Sleep ◽  
Apnea Syndrome

Heart rate variability (HRV) is mediated by at least three primary mechanisms: 1) vagal feedback from pulmonary stretch receptors (PSR), 2) central medullary coupling between respiratory and cardiovagal neurons (RCC), and 3) arterial baroreflex (ABR)-induced fluctuations. We employed a noninvasive experimental protocol in conjunction with a minimal model to determine how these sources of HRV are altered in obstructive sleep apnea syndrome (OSAS). Respiration, heart rate, and blood pressure were monitored in eight normal subjects and nine untreated OSAS patients in relaxed wakefulness and stage 2 and rapid eye movement sleep. A computer-controlled ventilator delivered inspiratory pressures that varied randomly from breath to breath. Application of the model to the corresponding subject responses allowed the delineation of the three components of HRV. In all states, RCC gain was lower in OSAS patients than in normal subjects ( P < 0.04). ABR gain was also reduced in OSAS patients ( P < 0.03). RCC and ABR gains increased from wakefulness to sleep ( P < 0.04). However, there was no difference in PSR gain between subject groups or across states. The findings of this study suggest that the adverse autonomic effects of OSAS include impairment of baroreflex gain and central respiratory-cardiovascular coupling, but the component of respiratory sinus arrhythmia that is mediated by lung vagal feedback remains intact.

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