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

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.