title: [Time-frequency analysis of ventricular fibrillation. An experimental study].
abstract: OBJECTIVE
  The analysis of frequency variability during ventricular fibrillation has yielded inconsistent results. We used an experimental model of ventricular fibrillation, with a short timescale, to analyze variations in frequency and their associated spatial distribution.
  
  
  METHODS
  Epicardial recordings of ventricular fibrillation were made in 10 perfused isolated rabbit heart preparations using a multiple electrode system (i.e., 240 unipolar electrodes). Both spectral and time-frequency analysis were used to derive the dominant frequency in the anterolateral wall of the left ventricle.
  
  
  RESULTS
  Linear regression analysis showed that there was a good correlation between the dominant frequency obtained using the two signal analysis methods: frequency (spectral analysis) = 1.01 x frequency (time-frequency analysis) -- 0.4 (r=0.9; P< .0001; standard error of the estimate, 2.2 Hz). In all cases except one, the dominant frequency exhibited a significant temporal variation on a short timescale (time-frequency analysis); the coefficient of variation was between 0.19 (0.06) and 0.24 (0.07) (NS). In all cases, there were significant differences between regions. The location at which the frequency was highest varied according to the timepoint considered, though it was predominantly in the apical or anterior zone.
  
  
  CONCLUSIONS
  In the absence of external modulating factors, the frequency of ventricular fibrillation exhibits temporal and spatial variations which can be observed at short timescales. In the free wall of the left ventricle, the dominant frequency is highest in the apical and anterior zones, and the maximum frequencies are most often found in these zones.
authors.affiliation: Servicio de Cardiología, Hospital Clínico Universitario de Valencia y Departamento de Medicina de la Universidad de Valencia, Valencia, España. francisco.j.chorro@uv.es
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Chorro
authors.forename: Juan
authors.initials: J
authors.lastname: Guerrero
authors.forename: Isabel
authors.initials: I
authors.lastname: Trapero
authors.forename: Luis
authors.initials: L
authors.lastname: Such-Miquel
authors.forename: Luis
authors.initials: L
authors.lastname: Mainar
authors.forename: Joaquín
authors.initials: J
authors.lastname: Cánoves
authors.forename: Estrella
authors.initials: E
authors.lastname: Blasco
authors.forename: Angel
authors.initials: A
authors.lastname: Ferrero
authors.forename: Juan
authors.initials: J
authors.lastname: Sanchís
authors.forename: Vicente
authors.initials: V
authors.lastname: Bodí
authors.forename: Luis
authors.initials: L
authors.lastname: Such
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004562:Electrocardiography; D004594:Electrophysiology; D006321:Heart / Q000503:physiopathology*; D011817:Rabbits; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000503:physiopathology*