title: Local electrogram-based criteria of cavotricuspid isthmus block.
abstract: BACKGROUND
  The efficacy and outcome of cavotricuspid isthmus ablation guided by local electrogram-based criteria of linear block were prospectively assessed.
  
  
  RESULTS
  In 40-consecutive patients (age 65+/-11 years) with typical right atrial (RA) flutter (cycle length = 255+/-31 msec), radiofrequency (RF) energy was delivered at electrograms in the isthmus coinciding with the center of the ECG plateau until termination of flutter, followed by local assessment of isthmus conduction during slow rate low-lateral RA pacing. 'Gaps' in the ablation line were located in the form of single or fractionated potentials centered on the isoelectric intervals of adjacent double potentials and ablated. Complete linear isthmus block was defined by the achievement of a complete corridor of parallel double potentials from the right ventricle to the inferior vena cava edge. Applications of 11+/-7 RF applications were required in all patients to achieve a complete line of double potentials separated by an isoelectric interval of 120+/-26 msec (range 60 to 190). After 6+/-3 RF applications, 6 (15%) patients had evidence of isthmus block using indirect RA activation sequence mapping without a complete line of double potentials. 5+/-5 further RF applications of eliminated local conduction and achieved complete linear block without altering descending septal RA activation. Conduction recovery occurred in 20 (50%) patients--1.85 times per patient-indicated by reversed changes in local electrograms eliminated by further ablation of the recovered gaps. After discharge, two recurrences (5%) occurred during a follow-up of 16+/-2 months.
  
  
  CONCLUSIONS
  Double potential mapping is an effective assessment modality for local isthmus conduction. Slow conduction limited to the ablation line is observed during ablation in 15% of patients.
authors.affiliation: CHU de Bordeaux, Hôpital Cardiologique du Haut-Lévêque Pessac, France.
authors.forename: D C
authors.initials: DC
authors.lastname: Shah
authors.forename: A
authors.initials: A
authors.lastname: Takahashi
authors.forename: P
authors.initials: P
authors.lastname: Jaïs
authors.forename: M
authors.initials: M
authors.lastname: Hocini
authors.forename: J
authors.initials: J
authors.lastname: Clémenty
authors.forename: M
authors.initials: M
authors.lastname: Haïssaguerre
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001282:Atrial Flutter / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D002036:Bundle of His / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D015203:Reproducibility of Results; D016896:Treatment Outcome; D014261:Tricuspid Valve; D014682:Vena Cava, Inferior