title: Mapping of focal atrial tachycardia with an uninterpretable activation map after extensive atrial ablation: tricks and tips.
abstract: BACKGROUND
  Atrial tachycardias (ATs) after 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. In this present study, we aim to characterize the electrophysiological features of ATs in this unique setting and to delineate an effective mapping strategy further.
  
  
  RESULTS
  In total, 13 patients (average age, 59±7 years) in a cohort of 80 patients referred for AT ablation were selected for the study. The patients all demonstrated an undistinguishable map not ready to be interpreted the 3-dimensional mapping. A total of 13 ATs were mapped with mean tachycardia cycle length of 296±70 ms. Two activation patterns were identified, which were referred to as pseudo-macroreentry and chaotic activation. 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/window of interest ratio range, 0.93-0.98). The latter refers to a focal AT exhibiting a disorderly color mapping display with IACT exceeding the window of interest duration (9 cases; IACT/window of interest 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 after previous extensive ablation. Two activation patterns were identified, which may help facilitate the mapping of focal ATs in this setting.
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Weizhu
authors.initials: W
authors.lastname: Ju
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Yang
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Hongwu
authors.initials: H
authors.lastname: Chen
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Fengxiang
authors.initials: F
authors.lastname: Zhang
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Gu
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Yu
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Mingfang
authors.initials: M
authors.lastname: Li
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Yang
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China.
authors.forename: Kejiang
authors.initials: K
authors.lastname: Cao
authors.affiliation: From the Department of Cardiology, The First Affiliated Hospital of Nanjing, Medical University, Nanjing, China. chenminglong@njmu.edu.cn.
authors.forename: Minglong
authors.initials: M
authors.lastname: Chen
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000601:surgery*; D016275:Atrial Function; D017115:Catheter Ablation / Q000009:adverse effects; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012086:Reoperation; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome
keywords: atrial ectopic tachycardia; focus; mapping; reentry