title: Resting muscle sympathetic nerve activity, cardiac metaiodobenzylguanidine uptake, and exercise tolerance in patients with left ventricular dysfunction.
abstract: BACKGROUND
  Sympathetic nerve overactivity and reduced exercise tolerance are characteristic features of patients with heart failure. However, to what extent sympathetic nerve overactivity contributes to limiting exercise tolerance has not been clearly defined.
  
  
  METHODS
  Myocardial iodine 123-metaiodobenzylguanidine (MIBG) scintigraphy, muscle sympathetic nerve activity (MSNA), and cardiopulmonary exercise testing were performed within 3 days in 30 patients with left ventricular dysfunction (LVD). Cardiac sympathetic nerve activity was estimated using H/M ratio and washout rate (WR) of 123I-MIBG imaging. MSNA was recorded by microneurography.
  
  
  RESULTS
  The patients with peak VO(2) < 20 mL/minute/kg (group II, n = 15) had significantly higher MSNA and WR, and lower H/M ratio than those with peak VO(2) > or = 20 mL/minute/kg (group I, n = 15) (P < .05). Peak VO(2) had negative correlations with MSNA and WR (r = 0.58, 0.56), and positive correlations with early H/M ratio and delayed H/M ratio (r = 0.71, 0.75) in group II. Moreover, MSNA had negative correlations with early H/M ratio and delayed H/M ratio (r = 0.78, 0.66), and a positive correlation with WR (r = 0.79) in group II. However, similar relations were not found in group I.
  
  
  CONCLUSIONS
  A link between cardiac and peripheral sympathetic nerve activities contributed to limiting exercise tolerance in patients with LVD patients and reduced exercise tolerance.
authors.affiliation: The Second Department of Internal Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
authors.forename: Masue
authors.initials: M
authors.lastname: Yoh
authors.forename: Fumio
authors.initials: F
authors.lastname: Yuasa
authors.forename: Jun
authors.initials: J
authors.lastname: Mimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yokoe
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kawamura
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Sugiura
authors.forename: Toshiji
authors.initials: T
authors.lastname: Iwasaka
mesh_terms: D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000294:innervation* / Q000503:physiopathology*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*
chemical_list: D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine