IMPROVED LATE POTENTIAL ANALYSIS IN FREQUENCY-DOMAIN

This work presents a technique to improve the identification of late p otentials (LP) in patients affected by greater arrhythmogenic right ve ntricular disease (GARVD). Several authors have documented the correla tion between GARVD and LP by means of time domain analysis. Moreover, the high incidence of bundle branch block in patients affected by GARV D suggests LP analysis in the frequency domain be performed. The metho d of spectral mapping of the ECG with Fourier transform was adopted. T his consists in dividing the ST segment into 25 subsegments and estima ting their frequency components by means of the fast Fourier transform . Recently, it was documented that this technique suffers from poor re producibility of results. Low reproducibility is the consequence of an improper localization of the analysed QRS segments. An algorithm to i ncrease the QRS end point identification reproducibility is proposed. An optimal QRS filter was adopted as well as a technique based on the Hilbert transform. This technique allowed the reliability of the norma lity factor estimates to be improved. The computed normality factors o n the XYZ leads and on the vector magnitude were used to classify pati ents and healthy subjects; 28 patients affected by greater arrhythmoge nic right ventricular disease and 35 healthy subjects were analysed in the study. High sensitivity was obtained with respect to GARVD, and c linical sustained ventricular tachycardia by means of a cluster analys is technique. By applying the technique proposed in this paper tile id entification. of LP in GARVD was increased from 47% to 88%, when clini cal sustained ventricular tachycardia was documented, whereas in patie nts affected by GARVD but not prone to sustained ventricular tachycard ia LP identification increases from 18% to 64%.