OBJECTIVES We aimed to clarify which recumbent position is preferred by pat
ients with congestive heart failure (CHF) and to evaluate whether cardiac a
utonomic nervous activity is different among three recumbent positions (sup
ine, 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 ge
nder-matched healthy subjects (66 +/- 7 years). Each subject underwent 24-h
ambulatory electrocardiographic monitoring. A channel was used to record t
he CM, 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 hi
gh-frequency (HF: 0.15 to 0.40 Hz) power was used as an index of vagal acti
vity 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 posi
tion was two-fold longer than that for the supine and left lateral decubitu
s positions. The increased cardiac sympathetic activity and decreased vagal
tone in CHF patients were normalized in the right lateral decubitus positi
CONCLUSIONS The right lateral decubitus position in patients with CHF may b
e a self-protecting mechanism of attenuating the imbalance of cardiac auton
omic nervous activity. (J Am Coll Cardiol 2001;37:1788-93) (C) 2001 by the
American College of Cardiology.