Evaluation of the Spatial Aspects of T-Wave Complexity in the Long-QT Syndrome

Abstract

Our data suggest that principal component analysis applied to 24-hour, 12-lead Holter recording adequately quantifies the complexity of ventricular repolarization and may become a useful noninvasive diagnostic tool in LQTS.

Techniques for Ventricular Repolarization Instability Assessment From the ECG

“…They lie on the assumption that larger dispersion in repolarization times results in a more complex T wave shape. Some of these descriptors rely on PCA to extract information from the T wave shape [52]. The total cosine R-to-T, T CRT , is defined as the cosine of the angle between the dominant vectors of depolarization and repolarization phases in a 3D loop and has been evaluated to compare repolarization in healthy subjects and hypertrophic cardiomyopathy patients [53].…”

Detection of hypertrophic cardiomyopathy is improved when using advanced rather than strictly conventional 12-lead electrocardiogram

“…Advanced ECG parameters derived from signal averaging. Signal averaging was performed using software developed by the authors 20,21,25,28 to generate results for parameters of: 1) 12-lead HF QRS ECG; 20 2) derived 3-dimensional ECG, using the Frank-lead reconstruction technique of Kors et al 29 to derive several vectocardiographic parameters previously described by Draper et al, 30 including for example the spatial mean QRS-T angle 17,28,31 and the magnitude, 30 azimuth /elevation 30 and beat-to-beat variation 16 of the spatial ventricular gradient and its components; and 3) QRS and Twaveform complexity via SVD, for example to derive parameters such as the principal component analysis (PCA) ratio, 21,22,32 the "relative residuum" 21,23 and the dipolar and nondipolar voltages 19,25 of the QRS and T waveforms. The majority of the parameters studied and their related detailed methods have been described in other recent publications.…”

Cardiac repolarization analysis using the surface electrocardiogram

“…These efforts resulted in some techniques based on principal component analysis (PCA), whose aim was to extract valuable information from the T-wave shape (Badilini et al 1995;Priori et al 1997).…”

“…ð4:8Þ was introduced to quantify the ST-T waveform shape (Priori et al 1997), although a square root was in the original definition. A T c value close to 1 means that the loop is highly extended in at least two dimensions.…”