Development of a new analytical method for the electrocardiogram using short-time first Fourier transforms

To detect the minute electric potential inside the QRS complex, a new frequ ency domain method was designed using short-time First Fourier Transforms ( SFFT) and high-frequency sampling (oversampling). SFFT improved the frequen cy resolution by oversampling that was applied to this analysis. The electr ic potential data of 15,000 points received weighted, running average proce ssing and was subtracted from the original waveform to reduce the low-frequ ency component. The data in a segment of 160ms, including QRS, was processe d by frequency analysis with the SFFT computation routine. The ECG of healt hy individuals was analyzed by this method and its usefulness evaluated. Th e processing waves of the X-axis, Y-axis, and Z-axis of a representative no rmal subject were formed into 3 groups of peak electric potential. SFFT ena bled the detection of the structure inside the QRS complex without signal a veraging, and is considered capable of evaluating the process of excitement inside the QRS complex in the various heart diseases.