title: Electrocardiographic characteristics in low atrial septum pacing.
abstract: OBJECTIVE
  The aim of the study was to compare P-wave morphology and duration in pacing from the low right atrial septal wall and the high right atrial appendage (RAA).
  
  
  METHODS
  The electrocardiogram (ECG) of 50 patients with low atrial septum (LAS) pacing and that of 50 patients with RAA pacing were compared with their electrocardiogram during sinus rhythm.
  
  
  RESULTS
  In the frontal plane, patients with LAS pacing showed a superior P-wave axis between -60 degrees and -90 degrees . In all patients with RAA pacing, a P-wave axis between 0 degrees and +90 degrees was observed as in sinus rhythm. In the horizontal plane, all patients with LAS pacing had an anterior P-wave axis between +90 degrees and +210 degrees , whereas all patients with RAA pacing had a posterior P-wave axis between -30 degrees and -90 degrees . The terminal part of biphasic P waves in lead V 1 in LAS pacing was always positive, a pattern that was never observed in P waves of sinus origin or in RAA pacing. P-wave duration was longer with RAA pacing compared with LAS pacing (115 +/- 19 vs 80 +/- 14 milliseconds [ P < .01]).
  
  
  CONCLUSIONS
  The total atrial activation time during LAS pacing is shorter than that during RAA pacing. The electrical atrial activation sequences in LAS pacing and RAA pacing are significantly different. The morphology of biphasic P waves in lead V1 during LAS pacing suggests that the initial part of activation occurs in the left atrium and the terminal part in the right atrium.
authors.affiliation: Department of Cardiology, St Lucas Andreas Ziekenhuis, 1061 AE Amsterdam, The Netherlands. w.g.devoogt@planet.nl
authors.forename: Willem G
authors.initials: WG
authors.lastname: de Voogt
authors.forename: Rob
authors.initials: R
authors.lastname: van Mechelen
authors.forename: Mike
authors.initials: M
authors.lastname: Scheffer
authors.forename: Addy J M
authors.initials: AJ
authors.lastname: van Miltenburg van Zijl
authors.forename: Abdou A
authors.initials: AA
authors.lastname: Elhendy
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D006325:Heart Atria; D006346:Heart Septum; D006801:Humans