title: The electromechanical effects of pacing at different sites within the right atrium.
abstract: OBJECTIVE
  To compare high right atrium (HRA) with right atrial appendage (RAA) pacing with respect to atrial electromechanical function.
  
  
  METHODS
  Eleven patients undergoing elective electrophysiological studies were studied in order directly to compare atrial conduction acutely associated with HRA and RAA pacing. Twenty-five patients with chronically implanted, active fixation leads in the HRA were compared with an age and sex matched group of 25 patients with chronically implanted, passive fixation leads in the RAA. For both studies recordings were taken in sinus rhythm then repeated when paced. Measured time intervals were intra- and interatrial activation times. P wave duration and time to onset of atrial systolic blood flow.
  
  
  RESULTS
  Right atrial pacing, when compared with sinus rhythm, significantly prolongs the interatrial activation time, the P wave duration and the time to onset of right and left atrial blood flow irrespective of site paced. Comparing the RAA group with the HRA group, there were no statistical differences for any of the measured parameters.
  
  
  CONCLUSIONS
  High right atrial free wall or the right atrial appendage pacing, when compared with sinus rhythm, is significantly detrimental to atrial electromechanical function. There is, however, no demonstrable difference between the two sites.
authors.affiliation: Department of Cardiology, Royal Shrewsbury Hospital, Shropshire, UK.
authors.forename: M R D
authors.initials: MR
authors.lastname: Belham
authors.forename: J
authors.initials: J
authors.lastname: Gill
authors.forename: M D
authors.initials: MD
authors.lastname: Gammage
authors.forename: P M
authors.initials: PM
authors.lastname: Holt
mesh_terms: D000328:Adult; D000368:Aged; D016280:Atrial Function, Right; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria; D006329:Heart Conduction System / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged