title: Simple and efficient identification of conduction gaps in post-ablation recurring atrial flutters.
abstract: OBJECTIVE
  Cavo-tricuspid isthmus (CTI) radiofrequency (RF) ablation is a curative therapy for common atrial flutter (AFl), but is associated with a recurrence rate of 5-26%. Although complete bidirectional conduction block is usually achieved, the recurrence of AF is due to recovered conducting isthmus tissue through which activation wavefronts pass. We evaluated a simple and efficient electrophysiological strategy, which pinpoints the ablation target.
  
  
  RESULTS
  Twenty-five patients (19 men), mean age 61 +/- 6, with recurrent AFl required a repeat ablation, 250 +/- 160 days after a successful RF CTI procedure. Transverse CTI conduction was monitored during AFl or coronary sinus (CS) pacing by a 24-pole mapping catheter positioned in the right atrium (RA), with the distal poles in the CS, proximal poles on the lateral RA, and intermediate poles on the CTI. A slow conduction area traversing the CTI (velocity, 37 +/- 22 vs. 98 +/- 26 cm/s on either side, P < 0.05) and a lower potential amplitude than at both sides (0.2 +/- 0.15 vs. 0.5 +/- 0.5 mV, P < 0.05), defined by a bayonet-shaped depolarization sequence, were considered to represent the incomplete line of block (InLOB). An ablation catheter was progressively dragged up to this InLOB, from the tricuspid annulus to the inferior vena cava, analysing the widely separated double potentials (DPs) until these coalesced. In nine patients (35%), the target conduction gap was a coalesced fractionated atrial potential within the InLOB (duration, 77 +/- 12 ms), and in 16 patients (65%), a narrow DP toward the healthy margins of this InLOB (duration, 28 +/- 15 ms). Adopting this strategy yields 100% successful re-ablation of recurring AFl leading to bidirectional block, with a mean 2.7 +/- 1.4 RF applications.
  
  
  CONCLUSIONS
  Transverse CTI mapping precisely locates the InLOB and helps find conduction gaps along the CTI in re-ablation procedures for common AFl.
authors.affiliation: Department of Cardiology, University Hospital Dijon, Hôpital Bocage, 3 Bd de Lattre de Tassigny, 21000 Dijon, France. gaby.nathalie@free.fr
authors.forename: Gabriel
authors.initials: G
authors.lastname: Laurent
authors.forename: Christian
authors.initials: C
authors.lastname: De Chillou
authors.forename: Géraldine
authors.initials: G
authors.lastname: Bertaux
authors.forename: Isabelle Magnin
authors.initials: IM
authors.lastname: Poull
authors.forename: Alexandra
authors.initials: A
authors.lastname: Martel
authors.forename: Marius
authors.initials: M
authors.lastname: Andronache
authors.forename: Stéphane
authors.initials: S
authors.lastname: Fromentin
authors.forename: Michel
authors.initials: M
authors.lastname: Fraison
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Gonzalez
authors.forename: François Saint
authors.initials: FS
authors.lastname: Pierre
authors.forename: Etienne
authors.initials: E
authors.lastname: Aliot
authors.forename: Jean Eric
authors.initials: JE
authors.lastname: Wolf
mesh_terms: D001282:Atrial Flutter / Q000503:physiopathology* / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012086:Reoperation; D016896:Treatment Outcome; D014261:Tricuspid Valve / Q000503:physiopathology / Q000601:surgery; D014682:Vena Cava, Inferior / Q000503:physiopathology / Q000601:surgery