title: Endocardial impedance mapping during circumferential pulmonary vein ablation of atrial fibrillation differentiates between atrial and venous tissue.
abstract: BACKGROUND
  Circumferential pulmonary vein ablation (CPVA) is an effective treatment for atrial fibrillation (AF). Accurate left atrial (LA) mapping is essential for creating lesions at the LA-pulmonary vein (PV) junction, avoiding PV stenosis.
  
  
  OBJECTIVE
  The purpose of this study was to establish whether endocardial impedance varies within the LA and PVs and whether it is a useful tool for mapping and ablation.
  
  
  METHODS
  Pilot Phase: Three-dimensional LA maps were created using CARTO. Impedance (Z) was measured using a radiofrequency generator at multiple points in the LA, PV ostia (PVO), and deep PVs in 79 patients undergoing their first AF ablation (group 1) and 29 patients undergoing repeat CPVA (group 2). Prospective Phase: In an additional 20 patients, using pilot phase data, one operator defined catheter tip location as either LA or PVO based on CARTO and fluoroscopy. A second operator blinded to CARTO simultaneously did the same based on impedance at 15 +/- 4 points per patient.
  
  
  RESULTS
  Group 1: Z(LA) was 99.4 +/- 9.0 omega. Z(PVO) was higher (109.2 +/- 8.5 omega), rising further as the catheter advanced into deep PV (137 omega +/- 18). Z(PVO) differed from Z(LA) by 9 +/- 4 omega. Group 2 had a lower Z(LA) and Z(PVO) compared with group 1 (P <.05). Impedance monitoring differentiated between LA and PVO, with 91% specificity and sensitivity, 96% positive predictive value, and 81% negative predictive value. At 3-month follow-up, no patients had evidence of PV stenosis on magnetic resonance imaging.
  
  
  CONCLUSIONS
  Impedance mapping reliably identifies the LA-PV transitional zone, facilitating AF ablation, and its use is associated with a low incidence of PV stenosis.
authors.affiliation: Division of Arrhythmology and Cardiac Electrophysiology, San Raffaele Hospital, Milan, Italy.
authors.forename: Christopher C E
authors.initials: CC
authors.lastname: Lang
authors.forename: Filippo
authors.initials: F
authors.lastname: Gugliotta
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Santinelli
authors.forename: Cézar
authors.initials: C
authors.lastname: Mesas
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tomita
authors.forename: Gabriele
authors.initials: G
authors.lastname: Vicedomini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Augello
authors.forename: Simone
authors.initials: S
authors.lastname: Gulletta
authors.forename: Patrizio
authors.initials: P
authors.lastname: Mazzone
authors.forename: Francesco
authors.initials: F
authors.lastname: De Cobelli
authors.forename: Alessandro
authors.initials: A
authors.lastname: Del Maschio
authors.forename: Carlo
authors.initials: C
authors.lastname: Pappone
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation*; D005260:Female; D005471:Fluoroscopy; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011667:Pulmonary Veins / Q000503:physiopathology / Q000601:surgery*; D012372:ROC Curve; D012008:Recurrence; D016896:Treatment Outcome