title: Electrophysiologic and anatomic characterization of sites resistant to electrical isolation during circumferential pulmonary vein ablation for atrial fibrillation: a prospective study.
abstract: BACKGROUND
  Catheter ablation (CA) by wide encirclement of pulmonary veins (WEPV) restores sinus rhythm in up to 95%. Complex PV-left atrial (LA) connections make achieving electrical isolation (EI) challenging. We examined anatomical and technical features associated with resistance to EI during WEPV in a prospective study.
  
  
  METHODS
  One hundred one consecutive patients with symptomatic AF underwent first-time CA guided by electroanatomic mapping and CT integration (Cartomerg). Following double-transseptal access, WEPV was performed. After completion of PV encirclement, the line was mapped and where no signal could be obtained, CA was performed inside the WE line at the site of earliest PV breakthrough on the circular mapping catheter. Sites of EI were tagged. Anatomic studies of corresponding regions of the venoatrial junction in 24 adult hearts were performed.
  
  
  RESULTS
  Sites resistant to EI were located at the inferior quadrant (P < 0.001) for the RSPV, superior quadrant (P < 0.001) for the RIPV, and the inferior and anterior quadrants (P < 0.001) for the LSPV. EI was significantly less frequent at the posterior quadrant (P < 0.001) for the LIPV. To achieve EI, CA was necessary inside the WE on the intervenous ridge on the right in 51% and on the left in 41%. The LPV/LAA ridge was investigated by anatomic studies that demonstrated considerable variation in the narrowest width (3-23.7 mm) and transmural thickness (1-5 mm).
  
  
  CONCLUSIONS
  Sites of EI after WEPV have a preferential distribution determined by anatomic features. CA on the intervenous ridge is required in a significant proportion of patients to achieve EI. Atrial folds and ridges increase myocardial thickness creating technical and anatomic challenges for achieving transmural lesions.
authors.affiliation: Department Of Cardiology, St Bartholomew's Hospital and Queen Mary College, University of London and the National Heart and Lung Institute, London, United Kingdom.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kistler
authors.forename: Siew Yen
authors.initials: SY
authors.lastname: Ho
authors.forename: Kim
authors.initials: K
authors.lastname: Rajappan
authors.forename: Michael
authors.initials: M
authors.lastname: Morper
authors.forename: Stuart
authors.initials: S
authors.lastname: Harris
authors.forename: Dominic
authors.initials: D
authors.lastname: Abrams
authors.forename: Simon C
authors.initials: SC
authors.lastname: Sporton
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schilling
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000601:surgery*; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011667:Pulmonary Veins / Q000000981:diagnostic imaging* / Q000601:surgery*; D011859:Radiography; D016896:Treatment Outcome