[Spectrotemporal mapping of signal-averaged electrocardiogram for identification of patients with sustained ventricular tachycardia].

Frequency analysis of multiple segments (spectrotemporal mapping, STM) of signal-averaged ECG (SAECG) considerably enhanced the detection of late potentials in patients with VTs/VF, but has not yet been verified in large samples. In this study, the modified protocol of STM, using the time when vector summed QRS forces last decreased to 40 microV at 25-250Hz filtering (40 microV/25-250Hz) as the onsets of the window, was performed in 119 normal subjects (group I), 26 patients with VTs/VF (group II), and 202 patients with organic heart diseases of different causes not accompanied by VTs/VF. The minimal normal factors (NF) of individual X, Y, Z leads were compared, significant differences were found between each 2 groups. 95% confidential values of minimal NF from group I were calculated, and NF < 33% on any lead was recommended as abnormal, ie, LP present. With this standard, 81% of the patients with VTs/VF, 94% of the normal subjects and 80% of the patients without VTs/VF were correctly discriminated despite the presence of intraventricular block (IVB, including bundle branch block and nonspecific intraventricular block). In conclusion, the method of STM of SAECG using terminal 40 microV/25-250Hz as window onsets offered promise for identification of patients with VTs/VF, and had better clinical applicability than time domain analysis for patients with IVB may not be excluded during STM.