title: Time course of left atrial mechanical recovery after linear lesions: normal sinus rhythm versus a chronic atrial fibrillation dog model.
abstract: BACKGROUND
  The extent of left atrial (LA) mechanical function recovery after creation of linear lesions using the loop catheter has not been determined.
  
  
  RESULTS
  LA mechanical function was assessed before and after linear lesions using transthoracic two-dimensional and Doppler echocardiography in two groups: (1) normal, which consisted of eight healthy dogs in normal sinus rhythm (NSR); and (2) atrial fibrillation (AF), which consisted of nine dogs in spontaneous AF for 6 months following rapid pacing-induced AF. NSR was restored with linear lesions in all AF dogs. All animals were in NSR 5 months after linear lesions. In the normal dogs, the maximal velocity of the transmitral flow "A" wave was reduced by 42% during the first week postablation and by 24% at 5 months versus preablation. At 5 months, no differences in LA function were noted between the normal and the AF group for all measured Doppler parameters. At 5 months, the LA systolic area in AF dogs was reduced by 40% (preablation 12.9 +/- 2.9 cm2, postablation 7.6 +/- 1.2 cm2; P < 0.01) and in the normal dogs by 21% (preablation 10.0 +/- 0.9 cm2, postablation 7.8 +/- 1.2 cm2; P < 0.02), being the same in both groups within 3 months of recovery.
  
  
  CONCLUSIONS
  The creation of linear lesions with the loop catheter does not result in LA expansion. In normal dogs, LA mechanical activity is reduced for 3 weeks postablation. The time course of LA mechanical function recovery is the same for the AF and the NSR dogs, and it is complete at 3 months postablation. At 5 months, LA systolic function parameters in both groups are reduced by 24% versus the preablation values of the normal dogs. Linear lesions result in a significant reduction in LA size.
authors.affiliation: Department of Medicine, University of Illinois at Chicago, 60612, USA. BAvitall@uic.edu
authors.forename: B
authors.initials: B
authors.lastname: Avitall
authors.forename: A
authors.initials: A
authors.lastname: Urbonas
authors.forename: D
authors.initials: D
authors.lastname: Urboniene
authors.forename: S
authors.initials: S
authors.lastname: Millard
authors.forename: R
authors.initials: R
authors.lastname: Helms
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D016279:Atrial Function, Left; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D002908:Chronic Disease; D004195:Disease Models, Animal; D004285:Dogs; D015150:Echocardiography, Doppler; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006339:Heart Rate; D008297:Male; D020127:Recovery of Function; D012849:Sinoatrial Node