Mapping of Focal Atrial Tachycardia with an Un-Interpretable Activation Map Following Extensive Atrial Ablation: Tricks and Tips
Background—Atrial tachycardias (ATs) following extensive ablation are increasingly common and challenging arrhythmias. The prolonged intra-atrial conduction time (IACT) during ATs in the milieu may complicate the mapping of focal ATs. The present study characterized the electrophysiological features of ATs in this unique setting and to further delineate an effective mapping strategy.
Methods and Results—In total, 13 patients (average age of 59±7 years) in a cohort of 80 patients referred for AT ablation were selected into the study. The patients all demonstrated an undistinguishable map not ready to be interpreted the three-dimensional mapping. A total of 13 ATs were mapped with mean tachycardia cycle length 296±70ms. Two activation patterns were identified, which were referred to as "pseudo macro reentry" and "chaotic activation", respectively. The former was a focal AT originating from the vicinity of an area of conduction block with the IACT less than the window of interest duration (4 cases, IACT/WOI ratio range 0.93-0.98). The latter refers to a focal AT exhibiting a disorderly color mapping display with IACT exceeding the WOI duration (9 cases, IACT/WOI ratio range 1.02-1.29). The IACT was determined after resetting the annotation. All ATs were successfully eliminated at the originating site.
Conclusions—We delineated a series of focal ATs in the setting of a significantly prolonged IACT encountered in patients following previous extensive ablation. Two activation patterns were identified, which may help facilitate the mapping of focal ATs in this setting.
- Received February 12, 2014.
- Revision received June 6, 2014.
- Accepted June 16, 2014.