Effects of Posture on Cardiac Autonomic Nervous
Activity in Patients With Congestive Heart Failure
Shoichi Miyamoto, MD,* Masatoshi Fujita, MD, FACC,† Hiroyuki Sekiguchi, P
Yoshiaki Okano, MD,§ Noritoshi Nagaya, MD, Kinzo Ueda, MD,* Shun-ichi Tamaki, MD,*
Ryuji Nohara, MD,¶ Shigeru Eiho, P
D,‡ Shigetake Sasayama, MD, FACC¶
Kyoto and Osaka, Japan
OBJECTIVES 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
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 Ϯ 7 years) and 17 age- and gender-matched healthy
subjects (66 Ϯ 7 years). Each subject underwent 24-h ambulatory electrocardiographic
monitoring. A channel was used to record the 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 ϫ 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
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. (J Am Coll
Cardiol 2001;37:1788 –93) © 2001 by the American College of Cardiology
Impaired autonomic nervous activity has been recognized as
a crucial component of congestive heart failure (CHF) (1),
and increased sympathetic activity has been reported as a
marker of poor prognosis of patients with CHF (2). The
spectral analysis of heart rate variability (HRV) has provided
much information on cardiac autonomic nervous activity.
Earlier studies have revealed an augmentation of sympa-
thetic drive and a withdrawal of parasympathetic tone in
patients with CHF (3–5). A decrease in HRV has also been
shown to be an independent predictor of arrhythmic events
and sudden death in CHF (6).
Patients with mild or moderate CHF may become
uncomfortable if they lie in the supine position without
elevation of the head. Therefore, these patients may prefer
other recumbent positions (i.e., trepopnea). In addition, we
have frequently observed that patients with CHF were apt
to be in the right lateral decubitus position. However, it
remains unclear whether cardiac autonomic nervous activity
is different among three recumbent positions in patients
with CHF. To elucidate these issues, we developed a
small-sized detector (3.2 cm ϫ 3.2 cm) for accurately
recording the postures under physiologic conditions during
daily life. It simultaneously assesses each patient’s posture
and cardiac autonomic nervous activity in combination with
Holter electrocardiographic (ECG) monitor recording.
Thus, the purpose of the present study was twofold: to
clarify which recumbent position is preferred by patients
with CHF, and to evaluate whether cardiac autonomic
nervous activity is affected by the various recumbent posi-
tions in patients with CHF during daily life.
Study subjects. The study population consisted of 17
male patients (mean age 66 Ϯ 7 years) with compen-
sated CHF due to coronary artery disease (CAD). Four
patients had three-vessel CAD, seven had two-vessel
CAD, and six had one-vessel CAD. Four patients had
New York Heart Association (NYHA) functional class I,
eight had functional class II, and ﬁve had functional class
III. The mean left ventricular ejection fraction was 32 Ϯ 6%.
Only beta-blocking therapy had been withdrawn at least
seven days earlier in all the patients. A constant diuretic
(53%), digitalis (12%), calcium antagonist (53%), nitrate
(82%), and angiotensin-converting enzyme inhibitor (65%)
dosing regimen was continued during the 24-h Holter
monitoring. Seven patients with diabetes mellitus were
From the *Division of Cardiology, Takeda Hospital, Kyoto, Japan; †College of
Medical Technology, Kyoto University, Kyoto, Japan; ‡Department of Systems
Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan; §Clinical
Laboratory Medicine, Kyoto University Hospital, Kyoto, Japan; Division of Cardi-
ology, National Cardiovascular Center, Osaka, Japan; and ¶Department of Cardio-
vascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
This study was supported by the “Research for the Future” Program (JSPS-RFTF 99
I 00201) from the Japan Society for the Promotion of Science.
Manuscript received August 31, 2000; revised manuscript received February 9,
2001, accepted February 15, 2001.
Journal of the American College of Cardiology Vol. 37, No. 7, 2001
© 2001 by the American College of Cardiology ISSN 0735-1097/01/$20.00
Published by Elsevier Science Inc. PII S0735-1097(01)01249-9