[The value of spectral mapping of electrocardiograms with Fourier transform in detecting late potentials].

The results of spectral mapping of the electrocardiogram (ECG) with Fourier transform of multi-segments (Blackman-Harris window, size 80 ms, 40 segments, time shift 2 ms) were studied in 7 patients with recurrent sustained ventricular tachycardia (VT, group 1), 16 patients with a history of myocardial infarction without VT (group 2) and 30 healthy volunteers (group 3). The 3-dimensional spectral plots in group 1 were characterized by the discrete high amplitude multi-peaks and increased high-frequency components at the end of QRS complex and early ST segment. The spectral-peak amplitude in group 1 (13.14 +/- 6.54 db) was significantly higher than that in group 2 and group 3 (P less than 0.05 and P less than 0.01), and the spectral-peak amplitude in group 2 (6.25 +/- 3.19 db) also higher than that in group 3 (4.30 +/- 2.00 db, P less than 0.05). The frequency spectra of late potentials mainly ranged from 40 to 100 Hz. The spectral peaks due to noises were present in all segments and irrespective of segment choice. The preliminary observation suggested that multi-segments spectral mapping of the ECG with Fourier transform offers a new analytic method for better identification of patients prone to sustained ventricular tachycardia.