Vectorcardiographic representation of concordant and discordant T-Wave alternans

Vectorcardiographic representation of T-wave alternans (TWA) has been presented in new coordinate system created by means of singular value decomposition where the first axis was in T-loop direction and other axes were perpendicular. Projection of T-loop vector on the plane perpendicular to the first axis was analyzed. The study shows that in case of healthy people and those with detectable TWA, in whom no ventricular events were occurred, shape of consecutive T-loops does not change significantly from beat to beat. Detected TWA is supposed to be concordant, which is relatively benign. In electrocardiograms of patients who had ventricular tachycardia or ventricular fibrillation events, the shape of T-loops changes from beat to beat. It is supposed to be discordant TWA. It was showed that T-loop shape analysis can serve as noninvasive tool for differentiation between concordant TWA and discordant one what can help in better identification of patients at risk of sudden cardiac death.