title: Attenuated respiratory modulation of chemoreflex-mediated sympathoexcitation in patients with chronic heart failure.
abstract: BACKGROUND
  Enhanced hypercapnic chemoreflex in chronic heart failure could modulate sympathetic nerve activity in a different manner depending on the severity of heart failure. This study was designed to evaluate the dynamic aspects of sympathoexcitation caused by central hypercapnic chemoreflex in patients with chronic heart failure.
  
  
  RESULTS
  In 21 patients with chronic heart failure, wavelet analysis was applied to elucidate the spectral components of muscle sympathetic nerve activity (MSNA) and instantaneous ventilation during hypercapnic chemoreceptor stimulation. Hypercapnia increased MSNA (83+/-8 versus 29+/-9 %, P<.01) and ventilation (209+/-27 versus 190+/-21%, P<.05) more in 12 symptomatic patients than in 9 asymptomatic patients. This hypercapnic chemoreflex exerted a greater influence on the sympathetic limb than on the ventilatory limb in the symptomatic patients. The wavelet analysis revealed that the within-breath sympathoinhibition in the symptomatic patients was attenuated as compared with that in the asymptomatic patients (0.33+/-0.03 vs. 0.44+/-0.04, P<.05).
  
  
  CONCLUSIONS
  The enhanced chemoreflex sympathetic drive and relative attenuation of ventilatory sympathoinhibition could contribute to exaggerated sympathoexcitation in patients with heart failure when they are exposed to carbon dioxide during exercise or sleep apnea.
authors.affiliation: Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueno
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Asanoi
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yamada
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Oda
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: Takashi
authors.initials: T
authors.lastname: Nozawa
authors.forename: Shutaro
authors.initials: S
authors.lastname: Takashima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D002628:Chemoreceptor Cells / Q000503:physiopathology*; D005260:Female; D006321:Heart / Q000294:innervation; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012018:Reflex / Q000502:physiology*; D012119:Respiration; D013564:Sympathetic Nervous System / Q000503:physiopathology*