Spectral analysis of signal-averaged electrocardiograms in patients with idiopathic ventricular tachycardia of left ventricular origin.
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.
Kinoshita
O
O
Division of Cardiology and Pathology, National Cardiovascular Center, Osaka, Japan.
Kamakura
S
S
Ohe
T
T
Yutani
C
C
Matsuhisa
M
M
Aihara
N
N
Takaki
H
H
Kurita
T
T
Shimomura
K
K
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