Hemodynamic variability and circadian rhythm in rats with heart failure: role of locomotor activity

1993 ◽  
Vol 264 (6) ◽  
pp. H2111-H2118 ◽  
Author(s):  
J. R. Teerlink ◽  
J. P. Clozel
Keyword(s):  
Myocardial Infarction ◽  
Heart Failure ◽  
Heart Rate ◽  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Power Spectral Analysis ◽  
Activity Level ◽  
Power Spectral ◽  
Coefficients Of Variation

Heart rate variability is known to be decreased by heart failure; however, the influences of concomitant diseases, changes in activity level, evolution through time, and abnormalities in the circadian rhythm are unknown. This study evaluated the influence of these factors by assessing hemodynamic variability in rats with heart failure (n = 8) and sham-operated controls (n = 8) through telemetric monitoring of heart rate, blood pressure, and locomotor activity for 8 wk. Hemodynamic variability was assessed by the standard deviation as well as hourly standard deviations and coefficients of variation of these variables over 48 h at 2, 4, and 8 wk after myocardial infarction. The circadian rhythm was investigated through power spectral analysis. Heart failure was associated with marked decreases in heart rate and mean arterial pressure variability and circadian rhythm without any differences in activity and no change through time. Heart failure in rats due to myocardial infarction in the absence of any confounding diseases is associated with marked abnormalities in hemodynamic variability and circadian rhythm independent of locomotor activity.

Heart Rate Variability and Outcome in Acute Severe Stroke: Role of Power Spectral Analysis

2004 ◽  
Vol 1 (3) ◽  
pp. 347-354 ◽  
Author(s):  
Arunodaya R. Gujjar ◽  
Talakad N. Sathyaprabha ◽  
Dindagur Nagaraja ◽  
Kandavel Thennarasu ◽  
Nithyananda Pradhan
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Spectral Analysis ◽  
Power Spectral Analysis ◽  
Severe Stroke ◽  
Power Spectral

Impact of Changes in Respiratory Frequency and Posture on Power Spectral Analysis of Heart Rate and Systolic Blood Pressure Variability in Normal Subjects and Patients with Heart Failure

1996 ◽  
Vol 91 (1) ◽  
pp. 35-43 ◽  
Author(s):  
John E. Sanderson ◽  
Leata Y. C. Yeung ◽  
Dickens T. K. Yeung ◽  
Richard L. C. Kay ◽  
Brian Tomlinson ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Heart Rate ◽  
Spectral Analysis ◽  
High Frequency ◽  
Low Frequency ◽  
Power Spectral Analysis ◽  
Normal Subjects ◽  
Power Spectral ◽  
Patients With Heart Failure

1. Autonomic dysfunction is a major feature of congestive cardiac failure and may have an important role in determining progression and prognosis. The low-frequency/high-frequency ratio derived from power spectral analysis of heart rate variability has been proposed as a non-invasive method to assess sympatho-vagal balance. However, the effects of different respiratory rates or posture are rarely accounted for, but may be relevant in patients with heart failure in whom clinical improvement is accompanied by a fall in respiratory rate and an increased proportion of the day in the upright position. 2. We have assessed the effect of controlled respiration at different rates (10, 15, 20 breaths/min or 0.17, 0.25 and 0.33 Hz), while supine and standing, on power spectral analysis of heart rate and blood pressure variability in 11 patients with heart failure and 10 normal subjects. 3. Heart rate variance and low-frequency power (normalized units) were reduced in patients with heart failure (absent in six). During controlled breathing while supine, the power of the high-frequency component was significantly greater at 10 breaths/min than at 20 breaths/min in patients with heart failure, whether expressed in absolute units (P = 0.005) or percentage of total power (P = 0.03). 4. On standing, controlled breathing in patients with heart failure produced less change in high-frequency power (P = 0.054), but the low-frequency/high-frequency ratio at lower respiratory rates was reduced (P = 0.05). In normal subjects, as expected, respiratory rate had a highly significant effect on high-frequency power. Also, in normal subjects there was the expected increase in heart rate low-frequency power (P = 0.04) moving from supine to standing with an increase in the low-frequency/high-frequency ratio (P = 0.003), while in the patients with heart failure this was absent, reflecting blunted cardiovascular reflexes. 5. Systolic blood pressure low- and high-frequency components and their ratio were significantly affected by respiration (P > 0.03) and change in posture (P > 0.03) in both patients with heart failure and normal subjects, with a significant increase in the low-frequency/high-frequency ratio (P = 0.03) on standing in patients with heart failure, indicating that autonomic modulation of blood pressure is still operating in heart failure. 6. Thus, respiratory rate and changes in posture have a significant effect on measurements derived from spectral analysis of heart rate and blood pressure variability. Studies that use power spectral analysis as a measure of sympatho-vagal balance should control for these variables.

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