Automatic electrocardiogram delineator based on the Phasor Transform of single lead recordings

The present work introduces a new ECG delineator, based on the Phasor Transform, which is able to operate in single lead recordings. The method converts each instantaneous ECG sample into a phasor, thus being able to deal very precisely with P and T waves, which are of notably lower amplitude than the QRS complex. Initially, the method relies on the detection of R peaks and, next, onset and offset of the QRS complex are identified. Finally, taking the QRS as a reference, P and T waves are detected and delineated. This delineator was validated with the QT database, available at Physionet, providing average values of sensitivity higher than 98.60% for the detection of all the significant ECG waves and fiducial points. Concretely, P wave sensitivity was 98.65% for the onset, peak and offset. The QRS onset and offset achieved a sensitivity of 99.85% and, finally, the T wave provided a sensitivity of 99.20% both for its peak and offset. Additionally, the average maximum time delineation error was lower than 6 ms and its standard deviation was in agreement with the accepted tolerances for expert physicians in the onset and offset identification for QRS, P and T waves. As a consequence, this new algorithm is able to achieve a performance similar to the top rated ECG delineators, but with notably lower computational cost.