Click on image to view larger version.

Figure 4 Functional Extension of Anatomical Intercaval Line of Block During Atrial Flutter

(Left panel) Activation map during induced atrial flutter (AFL) (cycle length, 134 ms). The thick black line indicates the line of fixed (lesion) block. The hatched areas indicate functional extension of the fixed line of block (LoB). The AFL re-entrant circuit travels up the right atrial free wall (arrow) and down the interatrial septum (dashed arrow). White asterisk indicates epicardial breakthrough; black asterisk indicates septal entry; a to d are recording sites from which electrograms are shown in the right panel. (Right panel) Electrograms recorded from the sites a to d. The double potentials in electrograms b and c indicate that a LoB exists between sites a and d during AFL. Abbreviations as in Figures 1 and 2. Reprinted, with permission, from Tomita et al. (17).