title: Modelling methodology of atrial fibrosis affects rotor dynamics and electrograms.
abstract: OBJECTIVE
  Catheter ablation is an effective technique for terminating atrial arrhythmia. However, given a high atrial fibrillation (AF) recurrence rate, optimal ablation strategies have yet to be defined. Computer modelling can be a powerful aid but modelling of fibrosis, a major factor associated with AF, is an open question. Several groups have proposed methodologies based on imaging data, but no comparison to determine which methodology best corroborates clinically observed reentrant behaviour has been performed. We examined several methodologies to determine the best method for capturing fibrillation dynamics.
  
  
  RESULTS
  Patient late gadolinium-enhanced magnetic resonance imaging data were transferred onto a bilayer atrial computer model and used to assign fibrosis distributions. Fibrosis was modelled as conduction disturbances (lower conductivity, edge splitting, or percolation), transforming growth factor-β1 ionic channel effects, myocyte-fibroblast coupling, and combinations of the preceding. Reentry was induced through pulmonary vein ectopy and the ensuing rotor dynamics characterized. Non-invasive electrocardiographic imaging data of the patients in AF was used for comparison. Electrograms were computed and the fractionation durations measured over the surface. Edge splitting produced more phase singularities from wavebreaks than the other representations. The number of phase singularities seen with percolation was closer to the clinical values. Addition of fibroblast coupling had an organizing effect on rotor dynamics. Simple tissue conductivity changes with ionic changes localized rotors over fibrosis which was not observed with clinical data.
  
  
  CONCLUSIONS
  The specific representation of fibrosis has a large effect on rotor dynamics and needs to be carefully considered for patient specific modelling.
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, IMB UMR 5251, CNRS, F-33400 Talence, France.
authors.forename: Caroline H
authors.initials: CH
authors.lastname: Roney
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, IMB UMR 5251, CNRS, F-33400 Talence, France.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Bayer
authors.affiliation: Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Sohail
authors.initials: S
authors.lastname: Zahid
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F- 33000, Bordeaux, France.
authors.forename: Marianna
authors.initials: M
authors.lastname: Meo
authors.affiliation: Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Patrick M J
authors.initials: PM
authors.lastname: Boyle
authors.affiliation: Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Trayanova
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F- 33000, Bordeaux, France.|Bordeaux University Hospital (CHU), Electrophysiology and Ablation Unit, F-33600 Pessac, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F- 33000, Bordeaux, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Dubois
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F- 33000, Bordeaux, France.|Department of Cardiac Imaging, Bordeaux University Hospital, Bordeaux, France.
authors.forename: Hubert
authors.initials: H
authors.lastname: Cochet
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France.|Univ. Bordeaux, IMB UMR 5251, CNRS, F-33400 Talence, France.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Vigmond
mesh_terms: D000200:Action Potentials; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D016275:Atrial Function; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005355:Fibrosis; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008279:Magnetic Resonance Imaging; D008955:Models, Cardiovascular; D066230:Patient-Specific Modeling; D011237:Predictive Value of Tests; D011379:Prognosis; D012815:Signal Processing, Computer-Assisted
keywords: Atrial fibrillation; Atrial fibrosis; Computer modelling; Electrogram fractionation; Non-invasive electrocardiographic imaging; Phase singularity mapping