Projective filtering of time-aligned ECG beats for repolarization duration measurement

Automatic measurement of ventricular repolarization duration is difficult and highly prone to errors. We propose to mitigate this problem by applying projective filtering to enhance the ECG signal prior to measurements. Our method performs time-alignment of ECG beats and then employs the rules of principal component analysis to the desired ECG reconstruction. As a result, significant noise reduction is obtained while distortions of the desired ECG components remain negligible. The proposed method is presented under white noise conditions; the influence on the precision of repolarization duration measurement is then investigated. Finally, the method's influence on evaluation of repolarization duration variability when the analyzed signals are contaminated with real electromyographic noise is discussed.