title: Spectral analysis of signal-averaged electrocardiograms in patients with idiopathic ventricular tachycardia of left ventricular origin.
abstract: BACKGROUND
  The signal-averaged ECG has been used to detect late potentials, and it is considered a noninvasive marker for areas of slow conduction requisite for reentrant arrhythmia. Late potentials are not usually found in patients with idiopathic ventricular tachycardia (VT); nevertheless, fragmented electrograms are often recorded in those patients during endocardial mapping. The purpose of this study was to investigate the spectral content of the signal-averaged ECGs with use of fast Fourier transform analysis (FFT) in patients with idiopathic VT of left ventricular origin.
  
  
  RESULTS
  Signal-averaged ECGs were recorded in 12 patients with idiopathic VT originating from the left ventricle (group 1) and 25 age-matched normal volunteers (group 2). Frequency analysis with FFT was performed with a Blackman-Harris window in a segment length of 120 msec from 40 msec before the end of the QRS complex, and the frequency spectrum was displayed in a three-dimensional graph. Area ratio 1 (area of 20-50 Hz/area of 10-50 Hz) and area ratio 2 (area of 40-100 Hz/area of 0-40 Hz) were calculated in all subjects. Late potentials defined by the time domain were negative in all subjects. The area ratios of group 1 were significantly higher than those of group 2. High-frequency components in the three-dimensional graph were confined within the QRS complex.
  
  
  CONCLUSIONS
  These results suggest that frequency analysis of signal-averaged ECGs with FFT is an available method for detecting the high-frequency component within the QRS complex in some patients with idiopathic VT of left ventricular origin.
authors.affiliation: Division of Cardiology and Pathology, National Cardiovascular Center, Osaka, Japan.
authors.forename: O
authors.initials: O
authors.lastname: Kinoshita
authors.forename: S
authors.initials: S
authors.lastname: Kamakura
authors.forename: T
authors.initials: T
authors.lastname: Ohe
authors.forename: C
authors.initials: C
authors.lastname: Yutani
authors.forename: M
authors.initials: M
authors.lastname: Matsuhisa
authors.forename: N
authors.initials: N
authors.lastname: Aihara
authors.forename: H
authors.initials: H
authors.lastname: Takaki
authors.forename: T
authors.initials: T
authors.lastname: Kurita
authors.forename: K
authors.initials: K
authors.lastname: Shimomura
mesh_terms: D000328:Adult; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography / Q000379:methods*; D004594:Electrophysiology; D005260:Female; D005583:Fourier Analysis; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D012815:Signal Processing, Computer-Assisted; D013610:Tachycardia / Q000175:diagnosis* / Q000503:physiopathology