Vector spectral combination of orthogonal leads using the Hartley transform for late potential analysis in Chagas disease

Time domain methods for Late Potentials (LP) analysis are widely used bur their results are affected by other cardiac pathologies like those found in chagasic patients with abnormal ventricular conduction. The use of an orthogonal lend vectorspectral combination using the Hartley transform has demonstrated to be a simple frequency domain method for the interpretation of abnormal ventricular potentials. In this work this approach for LP analysis of HRECG records from healthy subjects and chagasic patients is used. These records were taken from our SEARCH Chagas Database. The vectorspectral magnitude (S) was computed as the sum of the DHT spectra components of the XYZ leads in - 300 to -60Hz and 60 to 300Hz bands in a fixed 40ms or dynamic length time window at the end of QRS. Results showed that S is significantly lower in healthy subjects than in chagasic patients with abnormal EGG. The vector spectral analysis is a simple frequency, domain method for LP study that could detect positive patients with generalized myocardial disease.