Model interpretation of body surface potential QRST integral map variability in arrhythmia patients

Abstract

A necessary but not sufficient prerequisite of malignant arrhythmias is the existence of elevated static or dynamic repolarization dispersion (RD) of the ventricular myocardium. The early detection of this type of spatiotemporal impairment might have a clinical importance. Body surface potential mapping, using high resolution QRST integral maps, provides a unique noninvasive method for the beat-to-beat exploration of spatial RD. The sound theoretically proven relationship of ventricular RD and QRST integral maps has been known for many years, offering a novel electrocardiological imaging possibility. However, a “yes or no” type risk assessment can be achieved even without solving the ill-posed electrocardiological inverse problem by computing the body surface potential QRST integral map non-dipolarity index (NDI). In this study a multi-element numerical heart and a piecewise homogeneous chest model was used to estimate the sensitivity of the NDIs on pathological ventricular RD patterns. The tests included the physiological RD pattern as a reference and additional 83 pathological ones classified into 3 major types. All the local action potential (AP) modulation types were systematically swept through the anterior, lateral, posterior, septal and apical segments of the left ventricle. Additionally the impact of impaired conduction system and the involvement of the right ventricle were tested as well. It was concluded that the source level origin of the extreme NDIs was located in the apical part of the heart, due to permanent myocardial necrosis, temporally refracter regions or reversed transmural AP patterns.