Noninvasive Electrocardiographic Imaging

Abstract

Background:Cardiac arrhythmias continue to be a leading cause of death and disability. Despite this alarming fact, a noninvasive imaging modality for cardiac electrophysiology (EP) has not been developed. Standard electrocardiographic techniques attempt to infer electrophysiological processes in the heart from a limited number of recordings on the body surface. This traditional approach is limited in its ability to provide information on regional electrocardiac activity and to localize electrophysiological events in the heart (e.g., arrhythmogenic foci; regions of elevated dispersion of myocardial repolarization). This article reviews the development of a novel imaging modality (electrocardiographic imaging [ECGI]) for the reconstruction of cardiac electrical activity from potentials measured away from the heart (i.e., on the torso surface). The results presented demonstrate that ECGI can noninvasively reconstruct epicardial potentials, electrograms, and isochrones with good accuracy and resolution. Results:The locations of ectopic pacing sites are reconstructed within 10 mm of their actual positions. Dual epicardial pacing sites separated by 52 mm, 35 mm, and 17 mm can be resolved. The depth of intramural ectopic activity can be estimated and the direction of intramural activation spread can be determined from the reconstructed epicardial potential pattern and its evolution in time. Results from infarcted hearts demonstrate that ECGI can detect and reconstruct the abnormal electrophysiological substrate associated with the infarct. The figure‐of‐eight pattern of reentrant activation in the epicardial border zone during ventricular tachycardia is also reconstructed by ECGI noninvasively. Conclusions:These results demonstrate the potential of ECGI as a clinical noninvasive imaging modality for identifying patients at risk of cardiac arrhythmias and for guiding and evaluating antiarrhythmic interventions in such patients. A.N.E. 1999;4(3):340–359