title: Reentry mechanisms and ablation of ECG-typical atrial flutters involving the cavo-tricuspid isthmus and the proximal coronary sinus.
abstract: OBJECTIVE
  Reentry circuits of a rare typical atrial flutter (AFL) involving the cavo-tricuspid isthmus (CTI) and proximal coronary sinus (CS) are described based on electrophysiological data and effects of radiofrequency (RF).
  
  
  RESULTS
  Twelve patients with ECG-typical AFL in whom entrainment demonstrated that CTI and proximal CS were both part of the circuit were included. Initial RF target was CTI in 8 patients and proximal CS in 4. Success was defined as AFL termination/noninducibility. After CTI ablation, AFL cycle length (CL) increased in all: AFL persisted in 3, while in the other 5 AFL was interrupted but subsequently induced with the same morphology; before induction CTI bi-directional block was validated; success was obtained at the CS, targeting fragmented atrial potentials (APs). In those with first ablation at CS, AFL was interrupted in 3 with no AFL inducibility; in 1 AFL persisted with CL prolongation and was terminated at CTI. Two reentry patterns were identified: in 5 patients the inter-atrial septum as well as the mid-distal CS were outside of the circuit, while the CTI, proximal CS and Bachmann's bundle zone were inside, suggesting a left atrial component; in 1 patient electrophysiological mapping suggested an intra-CS circuit component. RF was successful in all without recurrence.
  
  
  CONCLUSIONS
  Electrophysiological mapping and RF effects suggest a continuum between the CTI and proximal CS in rare cases with ECG-typical AFL. RF inside the proximal CS, targeting fragmented APs, should be considered in any patient in whom CTI ablation failed to interrupt a typical AFL.
authors.affiliation: Cardiology Institute, Rhythmology Unit, Pitié-Salpêtrière Hospital, Paris, France.
authors.forename: Antonio
authors.initials: A
authors.lastname: De Sisti
authors.forename: Joelci
authors.initials: J
authors.lastname: Tonet
authors.forename: Manlio F
authors.initials: MF
authors.lastname: Márquez
authors.forename: Walid
authors.initials: W
authors.lastname: Amara
authors.forename: Henri
authors.initials: H
authors.lastname: Broustet
authors.forename: Faouzi
authors.initials: F
authors.lastname: Touil
authors.forename: Françoise
authors.initials: F
authors.lastname: Hidden-Lucet
mesh_terms: D000368:Aged; D001282:Atrial Flutter / Q000503:physiopathology* / Q000601:surgery; D017115:Catheter Ablation / Q000379:methods*; D054326:Coronary Sinus / Q000503:physiopathology* / Q000601:surgery; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D014261:Tricuspid Valve / Q000503:physiopathology* / Q000601:surgery
keywords: Atrial flutter; Atrial reentry; Cavo-tricuspid isthmus; Coronary sinus; Entrainment mapping; Radiofrequency catheter ablation