Model Interpretation of Non-Dipolar Integral Body Surface QRST Maps Randomly Appearing in Arrhythmia Patients

The source level interpretation of beat-to-beat QRST integral map non-dipolarity index (NDI) fluctuation has been studied, with a special regard to the generation of extremely large amplitude spikes. Computations relied on a numerical heart and chest model with modifiable action potential (AP) patterns, as well as ectopic activation wave generation possibility. These features are suitable for quantitative modeling of ventricular heterogeneity which is a prerequisite of malignant arrhythmias. According to the results skewed NDI distributions were generated by AP modulation, but extreme NDIs occurred due to apical ectopic beats propagating from the epicardium towards the endocardium.