Effects of posture on cardiac autonomic nervous activity in patients with congestive heart failure.
OBJECTIVE
We aimed to clarify which recumbent position is preferred by patients with congestive heart failure (CHF) and to evaluate whether cardiac autonomic nervous activity is different among three recumbent positions (supine, left lateral decubitus, right lateral decubitus) in patients with CHF.


BACKGROUND
It remains unclear whether cardiac autonomic nervous activity is different among three recumbent positions in patients with CHF.


METHODS
We studied 17 male CHF patients (66+/-7 years) and 17 age- and gender-matched healthy subjects (66+/-7 years). Each subject underwent 24-h ambulatory electrocardiographic monitoring. A channel was used to record the CM5 lead, and another to record the signal of the patient's posture with use of a newly developed small-sized detector (3.2 cm x 3.2 cm). By using spectral analysis of heart rate variability, frequency-domain measures were calculated and compared among the three recumbent positions. Normalized high-frequency (HF: 0.15 to 0.40 Hz) power was used as an index of vagal activity and the low frequency (0.04 to 0.15 Hz)/HF power ratio was used as an index of sympathovagal balance.


RESULTS
In patients with CHF, the time for the right lateral decubitus position was two-fold longer than that for the supine and left lateral decubitus positions. The increased cardiac sympathetic activity and decreased vagal tone in CHF patients were normalized in the right lateral decubitus position.


CONCLUSIONS
The right lateral decubitus position in patients with CHF may be a self-protecting mechanism of attenuating the imbalance of cardiac autonomic nervous activity.
Miyamoto
S
S
Division of Cardiology, Takeda Hospital, Kyoto, Japan.
Fujita
M
M
Sekiguchi
H
H
Okano
Y
Y
Nagaya
N
N
Ueda
K
K
Tamaki
S
S
Nohara
R
R
Eiho
S
S
Sasayama
S
S
D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011187:Posture; D012890:Sleep