Click on image to view larger version.

Figure 5 Example of intra-atrial re-entrant tachycardia (IART) from patient 6, who had undergone the modified Fontan procedure for mitral atresia. The atrial remnant was too small to accept the Halo catheter, so right atrial activation was recorded using two decapolar catheters positioned on the atrial septum (RAA) and on the lateral right atrial wall (RAP). Pacing was performed through the distal ablation catheter (ABLATE-D). Mapping revealed early, low-amplitude, fractionated potentials on the low lateral right atrial wall. Pacing from this site demonstrated concealed entrainment with a postpacing interval close to the tachycardia cycle length. The surface electrocardiographic leads are I, L, F, and V₁.