title: Left atrial appendage activity masquerading as pulmonary vein potentials.
abstract: BACKGROUND
  Despite extensive proximal ablation, all potentials frequently cannot be eliminated from the left pulmonary veins (PV). Methods and Results- PV electrograms were analyzed during sinus rhythm, coronary sinus, and left atrial appendage (LAA) pacing, and PV and LAA angiography performed. During pacing, an initial low-amplitude slow potential was recorded on the anterior aspect of the left superior PV and anticipated with shortest activation time by LAA pacing. Its timing coincided with posterior LAA activation, shown to be immediately adjacent to the left superior PV by angiography. In the left inferior PV, the first potential was smaller and less sharp, coinciding with adjacent low LA activation. Angiographically, the LAA was at least 15 mm from the left inferior PV. The second sharper potential in both left PVs was eliminated by proximal ablation.
  
  
  CONCLUSIONS
  Far field LAA activity consistently adds to PV myocardial electrograms in the left superior PV whereas lower, less sharp extravenous potentials in the left inferior PV originate from the inferior LA. They can be identified by LAA and coronary sinus pacing.
authors.affiliation: Division of Cardiology, University Hospital, Geneva, Switzerland. Dipen.Shah@hcuge.ch
authors.forename: Dipen
authors.initials: D
authors.lastname: Shah
authors.forename: Michel
authors.initials: M
authors.lastname: Haissaguerre
authors.forename: Pierre
authors.initials: P
authors.lastname: Jais
authors.forename: Meleze
authors.initials: M
authors.lastname: Hocini
authors.forename: Teiichi
authors.initials: T
authors.lastname: Yamane
authors.forename: Laurent
authors.initials: L
authors.lastname: Macle
authors.forename: Kee Joon
authors.initials: KJ
authors.lastname: Choi
authors.forename: Jacques
authors.initials: J
authors.lastname: Clementy
mesh_terms: D000200:Action Potentials; D020517:Atrial Appendage / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D018780:Body Surface Potential Mapping; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011667:Pulmonary Veins / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D011859:Radiography