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Figure 5 Color-Coded Isopotential Maps of VT

(A to F) Color-coded isopotential maps of ventricular tachycardia (VT) (patient, view, labels, and arrows as in Figs. 2 and 3); right ventricular depolarization runs from the superior-basal aspect (A) in an inferior and leftward direction. In contrast to basic rhythm, conduction travels through the suspected critical channel and previous area of conduction block toward the anterior right ventricular wall (B). Subsequently, it spreads inferiorly toward the right ventricular apex (C), where it turns around the septum (D) and around the outflow tract (E) and finally returns to the superior-basal aspect of the right ventricle, closing the macro–re-entrant circuit within the right ventricle (F). A second VT could be induced in this patient running in the opposite direction as VT #1. The presumed critical channel as identified by dynamic substrate map at the anterior right ventricle wall was shared by both induced tachycardias. Accordingly, radiofrequency current was delivered to that area in a point-by-point mode perpendicular to the spread of activation. Abbreviations as in Figure 2.