title: Dual-loop circuits in postoperative atrial macro re-entrant tachycardias.
abstract: BACKGROUND
  Patients may develop dual-loop re-entrant atrial arrhythmias late after open-heart surgery, and mapping and catheter ablation remain challenging despite computer-assisted mapping techniques.
  
  
  OBJECTIVE
  The purpose of the study was to demonstrate the prevalence and characteristics of dual-loop re-entrant arrhythmias, and to define the optimal mapping and ablation strategy.
  
  
  METHODS
  40 consecutive patients (mean (SD) age 52 (12) years) with intra-atrial re-entrant tachycardia (IART) after open-heart surgery (with an incision of the right atrial free wall) were studied. Dual-loop IART was defined as the presence of two simultaneous atrial circuits. After an abrupt tachycardia change during radiofrequency ablation, electrical disconnection of the targeted re-entry isthmus from the remaining circuit was demonstrated by entrainment mapping. Furthermore, the second circuit loop was localised using electroanatomical mapping and/or entrainment mapping.
  
  
  RESULTS
  Dual-loop IART was demonstrated in eight (20%, 5 patients with congenital heart disease, 3 with acquired heart disease) patients. Dual-loop IART included an isthmus-dependant atrial flutter combined with a re-entry related to the atriotomy scar. The diagnosis of dual-loop IART required the comparison of entrainment mapping before and after tachycardia modification. Overall, 35 patients had successful radiofrequency ablation (88%). Success rates were lower in patients with dual-loop IART than in patients without dual-loop IART. Ablation failures in three patients with dual-loop IART were related to the inability to properly transect the second tachycardia isthmus in the right atrial free wall.
  
  
  CONCLUSIONS
  Dual-loop IART is relatively common after heart surgery involving a right atriotomy. Abrupt tachycardia change and specific entrainment mapping manoeuvres demonstrate these circuits. Electroanatomical mapping appears to be important to assist catheter ablation of periatriotomy circuits.
authors.affiliation: Swiss Cardiovascular Center Bern, University Hospital, Bern, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Seiler
authors.forename: Dorothy K
authors.initials: DK
authors.lastname: Schmid
authors.forename: Thiemo A
authors.initials: TA
authors.lastname: Irtel
authors.forename: Hildegard
authors.initials: H
authors.lastname: Tanner
authors.forename: Martin
authors.initials: M
authors.lastname: Rotter
authors.forename: Nicola
authors.initials: N
authors.lastname: Schwick
authors.forename: Etienne
authors.initials: E
authors.lastname: Delacrétaz
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D017115:Catheter Ablation / Q000379:methods; D003937:Diagnosis, Differential; D004594:Electrophysiology / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome