title: An approach to left septal slow pathway ablation.
abstract: BACKGROUND
  Slow pathway ablation or modification eliminates typical atrioventricular nodal re-entrant tachycardia (AVNRT), but in less than 5% of patients cannot be accomplished from the right side.
  
  
  METHODS
  Consecutive, consenting patients (n = 221), aged 37 ± 7 years, 177 women, with slow-fast AVNRT, underwent slow pathway ablation. Mapping was restricted to the inferior part of the triangle of Koch, and end-points of ablation were induction of a junctional rhythm with retrograde atrial conduction and non-inducibility of AVNRT. Unsuccessful cases were ablated via a transeptal approach from the left septum with the aid of a left-sided His recording electrode.
  
  
  RESULTS
  Right-sided ablation was successful in 217 of 221 cases. In four patients (1.8%), left-sided ablation was necessary. Procedure, fluoroscopy times, and number of lesions were 105 min (82.4-135) vs. 65 min (60-90) (p = 0.013), 31.9 (23.9-34.3) vs. 9.6 (6.2-14.2) min (p = 0.001), and seven (5.5-7.8) vs. four (4-5; p = 0.004) for left- vs. right-sided procedures, respectively. During a follow-up period of 1-3 years, three patients (1.3%) in the right group had AVNRT recurrence. All had residual dual pathway physiology following ablation, while only 20.3% of patients without AVNRT had residual dual AV nodal conduction (p < 0.001). No conduction disturbances were seen. In the left-sided ablation group, no AVNRT recurrences or AV block were seen.
  
  
  CONCLUSIONS
  Ablation with the protocol described offers a high success rate with an extremely low risk of AV block when left-sided ablation is necessary in patients with typical AVNRT who have failed a right-sided approach.
authors.affiliation: Department of Cardiology, Athens Euroclinic, 9 Athanassiadou St, Athens 11521, Greece. dkatritsis@euroclinic.gr
authors.forename: Demosthenes G
authors.initials: DG
authors.lastname: Katritsis
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Giazitzoglou
authors.forename: Theodoros
authors.initials: T
authors.lastname: Zografos
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Ellenbogen
authors.forename: A John
authors.initials: AJ
authors.lastname: Camm
mesh_terms: D000328:Adult; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000002:abnormalities* / Q000601:surgery*; D006346:Heart Septum / Q000601:surgery*; D006801:Humans; D008297:Male; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery*; D016896:Treatment Outcome