title: Central sympathetic inhibition augments sleep-related ultradian rhythm of parasympathetic tone in patients with chronic heart failure.
abstract: 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.
authors.affiliation: The Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
authors.forename: Tsugiyoshi
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Asanoi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueno
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yamada
authors.forename: Junya
authors.initials: J
authors.lastname: Takagawa
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kameyama
authors.forename: Tadakazu
authors.initials: T
authors.lastname: Hirai
authors.forename: Shinji
authors.initials: S
authors.lastname: Ishizaka
authors.forename: Takashi
authors.initials: T
authors.lastname: Nozawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: 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*
chemical_list: D013565:Sympatholytics; D016316:Guanfacine