Visualizing Localized Reentry With Ultra–High Density Mapping in Iatrogenic Atrial Tachycardia: Beware Pseudo-Reentry

BACKGROUND—The activation pattern of localized reentry (LR) in atrial tachycardia remains incompletely understood. We used the ultra–high density Rhythmia mapping system to study activation patterns in LR. METHODS AND RESULTS—LR was suggested by small rotatory activations (carousels) containing the full spectrum of the color-coded map. Twenty-three left-sided atrial tachycardias were mapped in 15 patients (age64±11 years). 16 253±9192 points were displayed per map, collected over 26±14 minutes. A total of 50 carousels were identified (median 2; quartiles 1–3 per map), although this represented LR in only n=7 out of 50 (14%)here, rotation occurred around a small area of scar (