title: Mapping-guided ablation of the cavotricuspid isthmus: a novel simplified approach to radiofrequency catheter ablation of isthmus-dependent atrial flutter.
abstract: BACKGROUND
  Because the anatomic features of the cavotricuspid isthmus (CTI) are complex, radiofrequency (RF) energy requirements for CTI ablation may vary at each point within the CTI. Conventionally, multiple-site mapping has been required for determining CTI conduction block.
  
  
  OBJECTIVE
  The purpose of this study was to develop a more efficacious method for ablation of isthmus-dependent atrial flutter.
  
  
  METHODS
  Forty consecutive patients underwent CTI ablation using a CTI mapping-guided approach (20 patients) or a conventional approach (20 patients). In the CTI mapping-guided approach, an octapolar catheter was positioned on the CTI parallel to, and downstream from, the intended ablation line in order to map and ablate the breakthrough point.
  
  
  RESULTS
  Complete CTI block was achieved in all study patients. CTI mapping of incomplete ablation lines revealed that the site with the shortest interval between double potentials did not always coincide with the conduction gap. Disappearance of a breakthrough pattern on the CTI electrograms corresponded to creation of complete CTI block. During ablation, CTI mapping exhibited pseudo-CTI block in 8% of patients in the clockwise direction and 63% of patients in the counterclockwise direction. The number and total time of RF applications were significantly lower with the CTI mapping-guided approach than with the conventional approach (7.7 +/- 3.9 applications vs 13.8 +/- 8.9 applications and 8.9 +/- 4.4 minutes vs 16.3 +/- 11.9 minutes, respectively, P <.05). In the CTI mapping-guided approach, RF applications were not required along the entire CTI in 7 patients (35%).
  
  
  CONCLUSIONS
  This simplified technique was feasible for creating and determining complete CTI block, with fewer RF applications required.
authors.affiliation: First Department of Internal Medicine, Nippon Medical School, Tokyo, Japan. maru@nms.ac.jp
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Maruyama
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Miyauchi
authors.forename: Yu-Ki
authors.initials: YK
authors.lastname: Iwasaki
authors.forename: Norishige
authors.initials: N
authors.lastname: Morita
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Miyamoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tadera
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ino
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Atarashi
authors.forename: Takao
authors.initials: T
authors.lastname: Katoh
authors.forename: Teruo
authors.initials: T
authors.lastname: Takano
mesh_terms: D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D018780:Body Surface Potential Mapping; D017115:Catheter Ablation; D005260:Female; D006327:Heart Block; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014261:Tricuspid Valve / Q000503:physiopathology / Q000601:surgery*