title: Vagal activity modulates spontaneous augmentation of J-wave elevation in patients with idiopathic ventricular fibrillation.
abstract: BACKGROUND
  Although J-wave elevation in the inferolateral leads could be related to idiopathic ventricular fibrillation (IVF), little is known about the pathophysiologic characteristics of J-wave elevation in patients with IVF.
  
  
  OBJECTIVE
  This study aimed to determine the relationship between augmentation of J-wave elevation and changes in RR interval or autonomic nervous activities in patients with IVF.
  
  
  METHODS
  Eight patients with IVF and 22 controls with J-wave elevation (≥0.1 mV) in lead V5 were studied. The J-wave amplitude was automatically measured in lead CM5 of a digital Holter electrocardiogram, and the J-RR relationship was determined. Based on the analysis of heart rate variability, the relationship between the J-wave amplitude and the natural logarithm of high-frequency (HF) components (J-ln HF relationship) or the ratio of low frequency (LF) components to HF components (J-LF/HF relationship) was also determined.
  
  
  RESULTS
  The J-RR slope (mm/s) was greater in patients with IVF than in controls (3.5 ± 0.7 vs 2.4 ± 0.8; P <.01), as was J-wave amplitude (mm) at an RR interval of 1.2 seconds (2.8 ± 0.9 vs 2.0 ± 0.6; P <.05). The J-wave amplitude was correlated positively with ln HF and negatively with LF/HF, and the slopes of both J-ln HF and J-LF/HF regression lines were greater in patients with IVF than in controls. During an entire 24-hour period, there was no difference between the 2 groups in either HF or LF/HF. Nine of the total 11 episodes (82%) of spontaneous ventricular fibrillation occurred between 18:00 and 6:00.
  
  
  CONCLUSIONS
  In patients with IVF as compared with control subjects, J-wave elevation was more strongly augmented during bradycardia and was associated with an increase in vagal activity. This could be related to the occurrence of ventricular fibrillation predominantly at night in patients with IVF.
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan. kmizu@med.u-toyama.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Mizumaki
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Nishida
authors.forename: Jotaro
authors.initials: J
authors.lastname: Iwamoto
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Nakatani
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tsuneda
authors.forename: Naoya
authors.initials: N
authors.lastname: Kataoka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D001919:Bradycardia / Q000503:physiopathology; D016022:Case-Control Studies; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D014630:Vagus Nerve / Q000503:physiopathology*; D014693:Ventricular Fibrillation / Q000503:physiopathology*