title: Usefulness of the noncontact mapping system to elucidate the conduction property for the treatment of common atrial flutter.
abstract: BACKGROUND
  The functional role of the cavotricuspid isthmus (CTI) for common atrial flutter (cAFL) remains to be elucidated. In the present study, we examined whether the EnSite system (St. Jude Medical, St. Paul, MN, USA), a noncontact mapping system, is useful to evaluate the conduction properties of CTI to minimize radiofrequency (RF) ablation applications for cAFL.
  
  
  METHODS
  We enrolled 22 consecutive patients with cAFL (64.1 ± 9.5 years old, M/F 21/1) treated with the EnSite system and examined the conduction properties during cAFL and during atrial pacing. In addition, the effectiveness of the system was evaluated in comparison with the conventional ablation group (67 ± 8.9 years old, n = 15, M/F 13/2).
  
  
  RESULTS
  In 11 out of the 22 patients, CTI block line was achieved by fewer RF applications on a presumed single activation pathway which the EnSite system showed (point ablation [PA] group), and the remaining 11 patients needed additional linear ablation (additional ablation [AA] group). The number of RF applications in the PA group was significantly smaller than that in the conventional group. During the lower lateral right atrial pacing at a cycle length of 600 ms, the CV of the CTI in the PA group was smaller compared to that in the AA group (1.36 ± 0.61 vs 2.17 ± 0.66 m/s, P < 0.05), although the CV during cAFL (averaged cycle length 245 ± 34 ms) was not different in both groups.
  
  
  CONCLUSIONS
  These results indicate that targeting the presumed single line identified by EnSite could be an optional therapy for cAFL RF ablation, and diverse conduction properties in CTI are related to the success rate of this procedure. (PACE 2012;35:1464-1471).
authors.affiliation: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Kondo
authors.forename: Koji
authors.initials: K
authors.lastname: Fukuda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Wakayama
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakano
authors.forename: Yuhi
authors.initials: Y
authors.lastname: Hasebe
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimokawa
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001282:Atrial Flutter / Q000503:physiopathology* / Q000601:surgery*; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation / Q000295:instrumentation*; D016009:Chi-Square Distribution; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D014261:Tricuspid Valve / Q000503:physiopathology / Q000601:surgery; D014684:Venae Cavae / Q000503:physiopathology / Q000601:surgery