title: Augmented single-unit muscle sympathetic nerve activity in heart failure with chronic atrial fibrillation.
abstract: Atrial fibrillation (AF) is a common complication in heart failure (HF) patients. However, it remains unclear whether irregular ventricular response patterns induced by AF increase sympathetic nerve activity. We measured resting multi- and single-unit muscle sympathetic nerve activity (MSNA) in 21 age-matched HF patients with chronic AF (n = 11) rhythm or sinus rhythm (SR, n = 10). The multi-unit MSNA, which was expressed as total activity, was similar between HF + AF patients and HF + SR patients. However, the single-unit MSNA in HF + AF patients was significantly greater than that in HF + SR patients (62 ± 9 spikes min(-1) vs. 42 ± 4 spikes min(-1), P < 0.05). Moreover, the incidence of multiple firing of single-unit MSNA within a given burst was augmented in HF + AF patients as compared with HF + SR patients (48 ± 8% vs. 26 ± 3%, P < 0.01). A significant negative relationship was observed between the reduced diastolic pressure induced by a prolonged cardiac interval in AF subjects and single-unit MSNA frequency within one cardiac interval in each HF + AF subject. The firing characteristics of single-unit MSNA were different between HF patients with AF and HF patients with SR; particularly, those with a prolonged long RR interval showed multiple firings of single-unit MSNA. These findings suggest that AF per se leads to the instantaneous augmentation of single-unit MSNA induced by decreased diastolic pressure, which might partially contribute to disease progression in HF patients.
authors.affiliation: Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa, University, 13-1 Takara-machi, Kanazawa 920-8641, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Ikeda
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Murai
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kaneko
authors.forename: Soichiro
authors.initials: S
authors.lastname: Usui
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kobayashi
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakano
authors.forename: Keiko
authors.initials: K
authors.lastname: Ikeda
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Takashima
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kato
authors.forename: Masaki
authors.initials: M
authors.lastname: Okajima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Furusho
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takamura
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology*; D017704:Baroreflex; D001794:Blood Pressure; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010543:Peroneal Nerve / Q000502:physiology; D017534:Radial Artery / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*