title: Paraseptal accessory connections in the proximity of the atrioventricular node and the His bundle. Additional observations in relation to the ablation technique in a high risk area.
abstract: BACKGROUND
  Paraseptal pathways, namely, accessory connections (AC) in the vicinity of the atrioventricular node (AVN) and the bundle of His, are associated with a high risk of complete atrioventricular block (AVB) during transcatheter radiofrequency ablation (RFA) in the Electrophysiology Laboratory. In previously reported series of ablation of paraseptal ACs, the coexistence of multiple ACs in this high-risk region has rarely been mentioned.
  
  
  RESULTS
  We studied 15 patients undergoing RFA of paraseptal ACs 2 of whom had dual pathways with an additional midseptal pathway revealed after the elimination of the anteroseptal target AC. The fundamental goal of the pre-ablation electrophysiological mapping was the clear-cut determination of anatomical site with His bundle recording activity. This required unique pharmacological and programmed electrical stimulation manipulations in 8 patients in whom His bundle recording activity was only temporarily possible. After identifying the corresponding His bundle site, special attention was given to the ablation catheter being situated at least 3 mm away, thus recording minimal or no His bundle activity. Additional precautions were taken so that the delivered therapy was of minimal duration and powered by temperature regulation with immediate interruption in case of AVB or nodal rhythm appearance. With this therapeutic approach, 16 of the 17 paraseptal ACs were ablated successfully with the inadvertent induction of AVB in only 1 patient. In the patient with persistent ventricular preexcitation after the ablation session, modification of both the AC and the AVN was noted so that the previously easily induced reciprocating atrioventricular tachycardia was no longer so, using programmed stimulation.
  
  
  CONCLUSIONS
  Transcatheter radiofrequency ablation is a feasible and effective radical therapy for patients with paraseptal ACs, provided the His bundle site has first been clearly defined and the coexistence of other nearby tracts has been excluded.
authors.affiliation: University Cardiac Department, Hippokration General Hospital, Athens, Greece. kgatzoulis@med.uoa.gr
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Gatzoulis
authors.forename: Theodoros
authors.initials: T
authors.lastname: Apostolopoulos
authors.forename: Xenofon
authors.initials: X
authors.lastname: Costeas
authors.forename: Hlias
authors.initials: H
authors.lastname: Sotiropoulos
authors.forename: Fanis
authors.initials: F
authors.lastname: Papafanis
authors.forename: Christodoulos
authors.initials: C
authors.lastname: Stefanadis
authors.forename: Pavlos
authors.initials: P
authors.lastname: Toutouzas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002036:Bundle of His / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation / Q000009:adverse effects*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006327:Heart Block / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome