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 but their results are affected by other cardiac pathologies like those found in chagasic patients with abnormal ventricular conduction. The use of an orthogonal lead 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 the authors' SEARCH Chagas Database. The vectorspectral magnitude (S) was computed as the sum of the DHT spectra components of the XYZ leads in -300 to -60 Hz and 60 to 300 Hz bands in a fixed 40 ms 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 ECG. The vector spectral analysis is a simple frequency domain method for LP study that could detect positive patients with generalized myocardial disease.