title: Linear ablation of right atrial free wall flutter: demonstration of bidirectional conduction block as an endpoint associated with long-term success.
abstract: BACKGROUND
  Ablation for atypical atrial flutter (AFL) is often performed during tachycardia, with termination or noninducibility of AFL as the endpoint. Termination alone is, however, an inadequate endpoint for typical AFL ablation, where incomplete isthmus block leads to high recurrence rates. We assessed conduction block across a low lateral right atrial (RA) ablation line (LRA) from free wall scar to the inferior vena cava (IVC) or tricuspid annulus in 11 consecutive patients with atypical RA free wall flutter.
  
  
  RESULTS
  LRA block was assessed following termination of AFL, by pacing from the ablation catheter in the low lateral RA posterior to the ablation line and recording the sequence and timing of activation anterior to the line with a duodecapole catheter, and vice versa for bidirectional block. LRA block resulted in a high to low activation pattern on the halo and a mean conduction time of 201 +/- 48 ms to distal halo. LRA conduction block was present in only 2 out of 6 patients after termination of AFL by ablation. Ablation was performed during sinus rhythm (SR) in 9 patients to achieve LRA conduction block. No recurrence of AFL was observed at long-term follow-up (22 +/- 12 months); 3 patients developed AF.
  
  
  CONCLUSIONS
  Termination of right free wall flutter is often associated with persistent LRA conduction and additional radiofrequency ablation (RFA) in SR is usually required. Low RA pacing may be used to assess LRA conduction block and offers a robust endpoint for atypical RA free wall flutter ablation, which results in a high long-term cure rate.
authors.affiliation: Department of Cardiology, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Australia.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Snowdon
authors.forename: Richard
authors.initials: R
authors.lastname: Balasubramaniam
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Teh
authors.forename: Haris M
authors.initials: HM
authors.lastname: Haqqani
authors.forename: Caroline
authors.initials: C
authors.lastname: Medi
authors.forename: Raphael
authors.initials: R
authors.lastname: Rosso
authors.forename: Jitendra K
authors.initials: JK
authors.lastname: Vohra
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kistler
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Morton
authors.forename: Paul B
authors.initials: PB
authors.lastname: Sparks
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Kalman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001282:Atrial Flutter / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D004594:Electrophysiology; D023381:Endpoint Determination; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000473:pathology; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D016896:Treatment Outcome; D014682:Vena Cava, Inferior / Q000473:pathology