Study of morphological parameters of QRS loop using singular value decomposition during ischemia induced by coronary angioplasty

In this work we studied dynamic changes of ventricular depolarization loop evolution based on the Singular Value Decomposition (SVD) technique of 80 patients that underwent Percutaneous Transluminal Coronary Angioplasty (PTCA). The 8 independent ECG leads are subjected to SVD technique and are used to construct a new representation of QRS-SVD loops. In order to analyze the variations of QRS-SVD loops before, during and after PTCA, we proposed the following parameters: Maximum Module of the Depolarization Vector, Planar Area, Maximum Distance between Centroid and the Loop, Angle between the S1S2 plane and the Optimum Plane and Ratio between the Area and Perimeter. The results indicated that the parameters proposed show significant statistics differences during and after PTCA procedure vs. control. We concluded that the variations in the QRS-SVD loop before, during and after PTCA at ventricular depolarization can be described correctly through the proposed parameters.