title: Frequency characteristics and associations with the defibrillation threshold of ventricular fibrillation in patients with implantable cardioverter defibrillators.
abstract: OBJECTIVE
  The dominant frequency (DF) in frequency analyses is considered to represent the objective cycle length and complexity of activation under conditions of ventricular fibrillation (VF). However, knowledge regarding the mechanisms determining the DF in human VF is limited. We studied the characteristics of the DF of human VF and relationship between DF and the defibrillation threshold.
  
  
  METHODS
  Seventy-two implantable cardioverter-defibrillator patients and 211 VF were studied. Using defibrillation tests, we performed a frequency analysis with fast Fourier transformation. The correlations between DF and clinical characteristics, including the defibrillation threshold, were assessed.
  
  
  RESULTS
  The mean DF of all induced VFs was 5.2±0.8 Hz. The patients were divided into two groups according to DF: the low-DF (DF <5.2 Hz, n=32) and high-DF (DF ≥5.2 Hz, n=40) groups. The frequency of structural heart disease was significantly higher in the low-DF group. In addition, the QRS duration, QT interval and effective refractory period of the right ventricle (RV-ERP) were significantly longer in the low-DF group. A multivariate analysis showed RV-ERP to be the only independent predictor of DF. Excluding patients receiving group III anti-arrhythmic drugs, which are known to have potent defibrillation threshold effects, the defibrillation threshold was significantly lower in the low-DF group (p=0.026).
  
  
  CONCLUSIONS
  We found that the DF of human VF is associated with underlying heart disease, the cardiac function, cardiac conduction, ventricular refractoriness and defibrillation threshold. Our findings may be useful for identifying and managing patients with a high defibrillation threshold.
authors.affiliation: Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Iijima
authors.forename: Masaomi
authors.initials: M
authors.lastname: Chinushi
authors.forename: Osamu
authors.initials: O
authors.lastname: Saitoh
authors.forename: Kanae
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Keiko
authors.initials: K
authors.lastname: Sonoda
authors.forename: Nobue
authors.initials: N
authors.lastname: Yagihara
authors.forename: Akinori
authors.initials: A
authors.lastname: Sato
authors.forename: Daisuke
authors.initials: D
authors.lastname: Izumi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Furushima
authors.forename: Yoshifusa
authors.initials: Y
authors.lastname: Aizawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Minamino
mesh_terms: D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D017147:Defibrillators, Implantable; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014693:Ventricular Fibrillation / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy*; D055815:Young Adult
chemical_list: D000889:Anti-Arrhythmia Agents