Spectrotemporal Mapping. Increase of Signal Averaging Electrogram Sensitivity in Patients with Sustained Ventricular Tachycardia

pp 111-119

Abstract

Background

The detection of ventricular late potentials in time domain is limited by filters, noise and intraventricular conduction disturbances.

Method

The aim of this study was to resolve these problems, increasing the method sensitivity. A computarized signal averaged electrocardiogram, and spectrotemporal mapping in3dimensions (Fourier transformation) of non filtered Frank's derivation were made. The 3 dimensions graphic of spectrotemporal mapping was obtained from a 40 msec segment (15 msec before the terminal QRS and 25 msec after). The 40 msec area between60-120 Mz was measured in 20 normal voluntary patients (mean area 500.97 ± 231units), 29patients with inducible sustained ventricular tachycardia (269.40 ±281) and 5 patients with non-inducible autolimited ventricular tachycardia (AVT) (462.97 ± 267).

Results

The difference between normals and patients with sustained ventricular tachycardia was < 0.01, and the normals groups versus patients with auto limited ventricular tachycardia didn't show significant statistical differences. The normal value was superior to270units. It was found in 15 of 20 normals patients (specificity 75%) while, in 17 patients with sustained ventricular tachycardia this value was inferior (sensibility58.62%). The 80% of patients with autolimited ventricular tachycardia showed a similar area to normal patients. Ten of 29 patients with sustained ventricular tachycardia, didn't show late potentials in time domain (sensitivity66%), and 6 of them showed an inferior area to 270 units. The combined sensibility of both methods was 86.2%.

Conclusion

The spectrotemporal mapping allows to found significant differences between normals and patients with sustained ventricular tachycardia, and it increases 20% the sensibility of signal averaging electrocardiogram.