title: Effect of ablation pattern on mechanical function in the atrium.
abstract: BACKGROUND
  Atrial fibrillation (AF) is often treated with catheter ablation, which induces scar formation to isolate misfiring electrical signals in the left atrium. Successful ablation restores sinus rhythm at the cost of replacing viable myocardium with scar. The impact of ablation scar on mechanical function of the left atrium is poorly understood.
  
  
  OBJECTIVE
  We used a computational model to simulate various ablation patterns and determine their effect on atrial global and regional mechanical function.
  
  
  METHODS
  A coupled finite-element and hemodynamic circuit model of the left atrium that represents the regional and global mechanics in paroxysmal AF patients was modified to simulate different ablation patterns: step-wise pulmonary vein isolation (PVI), wide area circumferential ablation (WACA), and a posterior ablation developed by nContact, Inc (Morrisville, NC, USA). Atrial pressure-volume relationships and regional wall motion were compared among the models.
  
  
  RESULTS
  Ablation increased passive stiffness and decreased active work performed by the atrium. Active emptying volume decreased with increasing scar by up to 44% (11 mL) at a scar volume of 31%. At matched scar volumes, WACA decreased active emptying more severely than PVI and nContact. Similarly, wall motion was depressed most in the WACA model because WACA involved portions of the lateral wall with higher baseline motion.
  
  
  CONCLUSIONS
  Simulated ablation depressed atrial mechanical function to an extent that depended on both scar volume and location, primarily through reducing active emptying. Placing ablation scar in regions with high baseline motion resulted in greater depression of active function, while ablation of the posterior wall was less disruptive.
authors.affiliation: Department of Biomedical Engineering, University of Virginia, Charlottesville, VA.
authors.forename: Thien-Khoi N
authors.initials: TN
authors.lastname: Phung
authors.affiliation: Department of Biomedical Engineering, University of Virginia, Charlottesville, VA.
authors.forename: Christian B
authors.initials: CB
authors.lastname: Moyer
authors.affiliation: Department of Radiology, University of Virginia, Charlottesville, VA.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Norton
authors.affiliation: Department of Medicine, University of Virginia, Charlottesville, VA.
authors.forename: John D
authors.initials: JD
authors.lastname: Ferguson
authors.affiliation: Department of Biomedical Engineering, University of Virginia, Charlottesville, VA.|Department of Medicine, University of Virginia, Charlottesville, VA.|Robert M. Berne Cardiovascular Center, University of Virginia, Charlottesville, VA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Holmes
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000601:surgery*; D016275:Atrial Function; D002921:Cicatrix / Q000209:etiology / Q000503:physiopathology; D003198:Computer Simulation; D056966:Excitation Contraction Coupling; D006325:Heart Atria / Q000503:physiopathology* / Q000601:surgery*; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008955:Models, Cardiovascular; D016896:Treatment Outcome
keywords: atrial fibrillation; biomechanics; cardiac mechanics; catheter ablation; finite-element modeling; left atrium