title: The effects of short time right ventricular pacing on left atrial mechanical functions.
abstract: OBJECTIVE
  Left atrium (LA) plays an important role in left ventricular filling. It is well known that right ventricular apical pacing has unfavorable effects on ventricular systolic and diastolic performance. The aim of this study is to evaluate the LA mechanical functions with 2D echocardiography in patients with a permanent pacemaker after short time ventricular pacing.
  
  
  METHODS
  Echocardiographic examination was performed in 38 patients (mean age 63.0+/- 10.9, 18 female) with dual chamber pacemakers or defibrillators (< 20% ventricular pacing within previous 6 months, all of them on sinus rhythm) before and after 4 hours > 90% ventricular pacing at 70 beats per minute in DDD mode with an optimal AV interval. Left atrial volumes (LAV) including at the time of mitral valve opening (Vmax), at closure (Vmin), and at the onset of atrial systole (Volp) were measured. The passive emptying, conduit, active emptying and total emptying volume, stroke volumes were also calculated.
  
  
  RESULTS
  No significant differences were noted at baseline and after pacing for absolute Vmax, Volp, passive emptying, conduit, active emptying, total emptying volumes as well as the volumes indexed to body surface area (p >0.05).
  
  
  CONCLUSIONS
  Short - time RV pacing seems to have no acute effects on left atrial mechanical functions.
authors.affiliation: Baskent University Faculty of Medicine, Department of Cardiology, Ankara. gulmezoyku@yahoo.com
authors.forename: Oyku
authors.initials: O
authors.lastname: Gulmez
authors.forename: Ilyas
authors.initials: I
authors.lastname: Atar
authors.forename: Elif
authors.initials: E
authors.lastname: Sade
authors.forename: I Asli
authors.initials: IA
authors.lastname: Atar
authors.forename: Cagatay
authors.initials: C
authors.lastname: Ertan
authors.forename: Haldun
authors.initials: H
authors.lastname: Muderrisoglu
authors.forename: Bulent
authors.initials: B
authors.lastname: Ozin