title: Atrial activation mapping in sinus rhythm in the clinical electrophysiology laboratory: observations during Bachmann's bundle block.
abstract: BACKGROUND
  The high posterolateral right atrium (RA) is considered the "sinus node area," but we lack information on endocardial atrial activation in sinus rhythm. We studied RA and left atrial (LA) endocardial activation in the electrophysiology laboratory.
  
  
  RESULTS
  Thirty-five patients (21 men) aged 47 +/- 16.4 years (mean +/- SD) underwent RA mapping (22.2 +/- 3.8 points). In 21 patients, LA activation was mapped (11.1 +/- 3.9 points) through the coronary sinus (CS), right pulmonary artery, and/or a patent oval foramen. Fourteen patients had atrial arrhythmias, and 3 an ECG pattern of Bachmann's bundle block. Endocardial RA activation preceded P wave in 5 (-14 +/- 4.2 ms), coincided in 11, and followed P onset in 18 (16.7 +/- 6.6 ms). Location of the zero point varied from the superior vena cava to the low RA and from lateral to paraseptal RA. In 19 patients, activation started simultaneously in 2 to 5 points located >or=1 cm apart. RA activation was descending in most, but in 3 with low onset there was collision in the anterior and septal walls. In 15 of 21 patients, descending LA activation dominated, ending in the mid CS in 12, proximal CS in 1, and simultaneously throughout the CS in 2. In 3 with Bachmann's bundle block, CS activation was ascending and in 2 double potentials were recorded from the LA roof.
  
  
  CONCLUSIONS
  During stable sinus rhythm, RA activation can start in different areas or simultaneously over large areas resulting in different activation patterns, both in the RA and the LA. LA activation is predominantly descending, but in Bachmann's bundle block it becomes ascending, and double potentials suggest a location of block in the LA roof.
authors.affiliation: Cardiology Service, Hospital Universitario de Getafe, Madrid, Spain. fcosio@vitanet.nu
authors.forename: Francisco G
authors.initials: FG
authors.lastname: Cosío
authors.forename: Arturo
authors.initials: A
authors.lastname: Martín-Peñato
authors.forename: Agustín
authors.initials: A
authors.lastname: Pastor
authors.forename: Ambrosio
authors.initials: A
authors.lastname: Núñez
authors.forename: María Antonia
authors.initials: MA
authors.lastname: Montero
authors.forename: Carina P
authors.initials: CP
authors.lastname: Cantale
authors.forename: Salomao
authors.initials: S
authors.lastname: Schames
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001146:Arrhythmia, Sinus / Q000175:diagnosis / Q000503:physiopathology*; D018780:Body Surface Potential Mapping / Q000379:methods*; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012848:Sinoatrial Block / Q000175:diagnosis / Q000503:physiopathology*; D012849:Sinoatrial Node / Q000503:physiopathology*