title: Wavelet transform for analysis of heart rate variability preceding ventricular arrhythmias in patients with ischemic heart disease.
abstract: BACKGROUND
  Studies evaluating changes in HRV preceding the onset of ventricular arrhythmias using conventional techniques have shown inconsistent results. Time-frequency analysis of HRV is traditionally performed using short-term Fourier transform (STFT). Wavelet transform (WT) may however be better suited for analyzing non-stationary signals such as heart rate recordings.
  
  
  RESULTS
  We studied patients with a history of myocardial infarction implanted with a defibrillator with an extended memory. The RR intervals during the 51 min preceding ventricular events requiring electrical therapy were retrieved, and HRV studied by WT and STFT. 111 episodes of ventricular arrhythmia were retrieved from 41 patients (38 males, age 64 +/- 8 years). Heart rate increased significantly before arrhythmia. There was no significant variation in low frequency / high frequency components (LF/HF) observed for the group as a whole, probably due to a great degree of heterogeneity amongst individuals. A subset of 30 patients also had heart rate recordings performed during normal ICD follow-up. WT did not show any difference in HRV before arrhythmia onset and during control conditions.
  
  
  CONCLUSIONS
  Variations in HRV before onset of ventricular arrhythmias were not apparent in this large dataset, despite use of optimal tools for studying time-frequency analysis.
authors: Unité 50, Hôpital Louis-Pradel, Lyon, France. haran.burri@hcuge.ch
authors: Haran
authors: H
authors: Burri
authors: Philippe
authors: P
authors: Chevalier
authors: Mohammad
authors: M
authors: Arzi
authors: Paul
authors: P
authors: Rubel
authors: Gilbert
authors: G
authors: Kirkorian
authors: Paul
authors: P
authors: Touboul
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology*; D012042:Registries