Session PB1.2

Study of Morphological Parameters of QRS Loop Using Singular Value Decomposition during Ischemia Induced by Coronary Angioplasty

R Correa, PD Arini*, E Laciar, P Laguna, R Jané

Instituto Argentino de Matemática
Buenos Aires , Argentina

Aim: The aim of this work is to study the QRS loop evolution based on the Singular Value Decomposition (SVD) technique during induced ischemia by the Percutaneous Transluminal Coronary Angioplasty (PTCA) method.
Methods:The study group consisted of 80 patients receiving PTCA in one of their major coronary arteries. The 8 standard electrocardiographic leads (I, II and V1-V6) are subjected to SVD technique and their dominant 3 decomposed leads 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 procedure, it has been proposed in this study the following morphological parameters: Maximum Module of the Depolarization Vector (MMDV), Planar Area (PA), Maximum Distance between Centroid and the Loop (MDCL), Angle between the XY plane and the Optimum Plane (AXYOP) and Ratio between the Area and Perimeter (RAP). With the object to study the temporal evolution of each parameter, a series of Absolute Differences (AD) were computed as the difference between the mean value of the considered parameter at 10 s intervals during and after PTCA respect to its mean value at the first minute of Control Recording. The statistical analysis was realized by comparing the average of AD value before PTCA taken as control (C) versus the AD value during (Dti-tf) and after (Ati-tf) PTCA respectively; where ti-tf is the time interval defined in seconds. The statistical significant compared against control were: *p<.00001, #p<0.0005, †p<0.005, ‡p<0.001, §p<0.05.
Results: The results, mean±SEM, are: For MMDV parameter in C=25.8±2.7 uV; D50-60=89.1±9.2* uV; D110-120=89.7±9.6* uV; D170-180=94.4±11.3* uV; A50-60=68.6±8.4* uV. For PA parameter in C=(2.44±1.2)E3 uV2; D50-60=(3.9±1.2) E3* uV2; D110-120= (4.8±1.4)E3* uV2; D170-180=(4.3±1.5)E3† uV2; A50-60= (4.0±1.3)E3 (NS) uV2. For MDCL parameter in C=26.2±2.7 uV; D50-60=88.9±8.9* uV; D110-120=91.1±9.3* uV; D170-180=96.7±11.1* uV; A50-60=72.3±8.6* uV. For AXYOP parameter in C=(9.2±1.9)E-3 rad.; D50-60= (23.9±7.8)E-3† rad.; D110-120=(19.2±3.7)E-3§ rad.; D170-180=(19.0±4.5) E-3 (NS) rad.; A50-60=(29.0±9.6) E-3§ rad. For RAP parameter in C=106.76±12.33; D50-60=221.08±30.37*; D110-120=251.39±37.62§; D170-180=234.10±35.87#; A50-60=278.20±47.33‡.
Conclusions: The obtained results indicate that: 1) The AD values for MMDV, DMCL, RAP and AXYOP parameters showed an increased tendency during PTCA. Also, it has been observed than the AD values for PA parameter does not have a monotonically increase response, which is caused by the great dispersion in its values among the studied patients. 2) The variations in the QRS-SVD loop before during and after PTCA at ventricular depolarization can be described correctly through the proposed morphological parameters. 3) The temporal evolution of these parameters during and after PTCA can provide complementary information to the traditional ST-segment analysis in the study of myocardial ischemia.

(Abstract Control Number: 15)