title: Effect of atrial radiofrequency ablation designed to cure atrial fibrillation on atrial mechanical function.
abstract: BACKGROUND
  The effects of linear radiofrequency lesions in the atria for cure of atrial fibrillation on atrial contraction have not previously been quantified.
  
  
  RESULTS
  Atrial function was measured before and 30 +/- 24 days after a biatrial ablation procedure designed to cure atrial fibrillation in eight dogs and after a sham procedure in three dogs. Atrial mechanical function was assessed using Doppler diastolic blood flow velocities, atrial systolic pressure wave amplitude, and assessment of atrial contribution to cardiac output estimated by comparison of AV sequential pacing to ventricular pacing at the same heart rate. The mitral Doppler A/E velocity ratio was 1.03 +/- 0.45 before and 0.72 +/- 0.43 after ablation (P = 0.048). The tricuspid A/E ratio was 0.88 +/- 0.17 before and 0.71 +/- 0.12 after ablation (P = 0.04). The estimated atrial contribution to cardiac output was 18% +/- 9% before and 5% +/- 4% after ablation (P < 0.01). The left atrial systolic pressure wave amplitude was 2.8 +/- 1.5 mmHg before and 1.7 +/- 1.0 mmHg after ablation (P = 0.1). These changes were not observed in control dogs. Lesions covered 25% +/- 6% of the atrial endocardial surface.
  
  
  CONCLUSIONS
  Multiple linear radiofrequency lesions in the atria designed to cure atrial fibrillation may impair atrial contractility. Reduced atrial function is partly due to loss of atrial myocardial mass, but regional delays in atrial activation and splinting of the atria by scarring also may contribute.
authors.affiliation: Department of Cardiology, Westmead Hospital, New South Wales, Australia.
authors.forename: S P
authors.initials: SP
authors.lastname: Thomas
authors.forename: I A
authors.initials: IA
authors.lastname: Nicholson
authors.forename: G R
authors.initials: GR
authors.lastname: Nunn
authors.forename: A
authors.initials: A
authors.lastname: Rees
authors.forename: L
authors.initials: L
authors.lastname: Trieu
authors.forename: M P
authors.initials: MP
authors.lastname: Daly
authors.forename: E M
authors.initials: EM
authors.lastname: Wallace
authors.forename: D L
authors.initials: DL
authors.lastname: Ross
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D016275:Atrial Function; D001794:Blood Pressure; D002302:Cardiac Output; D006348:Cardiac Surgical Procedures / Q000295:instrumentation; D017115:Catheter Ablation / Q000295:instrumentation; D003971:Diastole; D004285:Dogs; D004867:Equipment Design; D008943:Mitral Valve / Q000503:physiopathology; D011184:Postoperative Period; D012039:Regional Blood Flow; D014261:Tricuspid Valve / Q000503:physiopathology