Estimation and removal of T wave component in atrial flutter ECG to aid non-invasive localization of ectopic source

Abstract

The use of the ECG as a diagnostic tool for analyzing supraventricular arrhythmia avoids invasive procedures prior to clinical intervention. Analysis of atrial activity may indicate properties of the underlying arrhythmia. In atrial flutter, there is a high synchroneity between atrial and ventricular activity. Statistical and classical separation methods are unlikely to work due to this dependency, impeding the extraction of the atrial activity. We propose a method using least square polynomial estimation to model the T wave component and subtract it from overlapped f-waves. After pre-processing, an initial f-wave was carefully segmented, representing pure atrial activity. Subsequent f-waves were detected and corrected by subtracting the T wave, modeled as a sum of weighted polynomials which minimize the least square error. To evaluate the method, vectorcardiographic loops were obtained using the inverse Dower transform. Loop parameters were obtained from eigenvectors and eigenvalues issued from principal component analysis. Using degree 3 polynomials allowed recovery of overlapped f-waves with significant improvement in 3 of 4 parameters (p < 0.05). f-waves overlapped by T waves can thus successfully be recovered using this method.