Endocardial mapping of electrophysiologically abnormal substrates and cardiac arrhythmias using a noncontact nonexpandable catheter

Noncontact Mapping of Arrhythmogenic Substrates. Introduction: In previous studies, we established methodology for reconstructing endocardial potential maps, electrograms, and isochrones from a noncontact intracavitary catheter during a single beat. Recently, we evaluated this approach using a 9-French (3-mm) spiral catheter in a normal heart preparation. Here we extend the approach to hearts with structural disease and examine its ability to detect and characterize abnormal electrophysiologic (EP) substrates and to map ventricular arrhythmias on a beat-by-beat basis. Methods and Results: Reconstruction of endocardial potentials from cavity potentials measured with 82 electrodes mounted on a 9-French spiral catheter was performed in an isolated canine left ventricle (LV). Endocardial potentials were recorded with 91 intramural needles, providing a gold standard for evaluating the noncontact reconstruction. Studies were performed in a normal LV (control) and the same LV 3 hours after left anterior descending coronary artery occlusion and ethanol injection to create an infarct. Abnormal EP characteristics over the infarct were faithfully reconstructed, including (1) low potentials and electrogram derivatives; (2) fractionated electrograms; (3) small deflections on electrograms reflecting local activation; and (4) slow discontinuous conduction transverse to fibers. During arrhythmia, beat-to-beat dynamic shifts of initiation site and activation pattern were captured by the reconstruction. Conclusion: Noncontact, nonexpendable catheter mapping can locate and characterize abnormal EP substrates and can capture the endocardial sequence of an arrhythmia during a single beat.