Central sympathetic inhibition augments sleep-related ultradian rhythm of parasympathetic tone in patients with chronic heart failure.
BACKGROUND
Abnormal sleep dynamics in patients with heart failure is one of the mechanisms for the relative predominance of central sympathetic outflow over parasympathetic tone. This study was designed to examine whether central sympathoinhibition could improve the sympathovagal imbalance related to rapid-eye-movement (REM)/non-REM ultradian sleep rhythm in these patients.


RESULTS
Beat-by-beat RR intervals of overnight electrocardiogram were serially subject to power spectral analysis in 14 patients with chronic heart failure and 13 age-matched subjects with normal cardiac function. To assess autonomic sleep dynamics, the ultradian rhythm was extracted from all-night consecutive high-frequency (HF) components of heart rate variability (HRV) before and after administration of an (alpha2)-adrenergic agonist, guanfacine. Night-time HRV in heart failure was characterized by an attenuated ultradian rhythm of HF-components with a concomitant reduction in averaged HF power. Guanfacine reduced blood pressure, heart rate, and plasma norepinephrine concentrations by 7%, 8%, and 34% (p < 0.01), respectively. After guanfacine, HF power rose by 154% (p < 0.01) with a prominent augmentation of the all-night ultradian rhythm (+361%, p < 0.01).


CONCLUSIONS
Central sympathoinhibition augments a sleep-related ultradian rhythm of parasympathetic tone, suggesting a potential benefit to autonomic balancing and sleep quality in patients with chronic heart failure.
Yamazaki
Tsugiyoshi
T
The Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
Asanoi
Hidetsugu
H
Ueno
Hiroshi
H
Yamada
Kunihiro
K
Takagawa
Junya
J
Kameyama
Tomoki
T
Hirai
Tadakazu
T
Ishizaka
Shinji
S
Nozawa
Takashi
T
Inoue
Hiroshi
H
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D004562:Electrocardiography / Q000379:methods; D005260:Female; D016316:Guanfacine / Q000494:pharmacology*; D006333:Heart Failure / Q000188:drug therapy / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology*; D012890:Sleep; D013565:Sympatholytics / Q000494:pharmacology*
D013565:Sympatholytics; D016316:Guanfacine