title: Structural contributions to fibrillatory rotors in a patient-derived computational model of the atria.
abstract: OBJECTIVE
  The aim of this study was to investigate structural contributions to the maintenance of rotors in human atrial fibrillation (AF) and possible mechanisms of termination.
  
  
  RESULTS
  A three-dimensional human biatrial finite element model based on patient-derived computed tomography and arrhythmia observed at electrophysiology study was used to study AF. With normal physiological electrical conductivity and effective refractory periods (ERPs), wave break failed to sustain reentrant activity or electrical rotors. With depressed excitability, decreased conduction anisotropy, and shorter ERP characteristic of AF, reentrant rotors were readily maintained. Rotors were transiently or permanently trapped by fibre discontinuities on the lateral wall of the right atrium near the tricuspid valve orifice and adjacent to the crista terminalis, both known sites of right atrial arrhythmias. Modelling inexcitable regions near the rotor tip to simulate fibrosis anchored the rotors, converting the arrhythmia to macro-reentry. Accordingly, increasing the spatial core of inexcitable tissue decreased the frequency of rotation, widened the excitable gap, and enabled an external wave to impinge on the rotor core and displace the source.
  
  
  CONCLUSIONS
  These model findings highlight the importance of structural features in rotor dynamics and suggest that regions of fibrosis may anchor fibrillatory rotors. Increasing extent of fibrosis and scar may eventually convert fibrillation to excitable gap reentry. Such macro-reentry can then be eliminated by extending the obstacle or by external stimuli that penetrate the excitable gap.
authors.affiliation: Department of Bioengineering, University of California San Diego, Mail Code 0412, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Gonzales
authors.affiliation: Department of Bioengineering, University of California San Diego, Mail Code 0412, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Vincent
authors.affiliation: Department of Physics, University of California San Diego, La Jolla, CA, USA Center for Theoretical Biological Physics, University of California San Diego, La Jolla, CA, USA.
authors.forename: Wouter-Jan
authors.initials: WJ
authors.lastname: Rappel
authors.affiliation: Department of Medicine, University of California San Diego, La Jolla, CA, USA Cardiac Biomedical Science and Engineering Center, University of California San Diego, CA, USA VA San Diego Healthcare System, San Diego, CA, USA.
authors.forename: Sanjiv M
authors.initials: SM
authors.lastname: Narayan
authors.affiliation: Department of Bioengineering, University of California San Diego, Mail Code 0412, 9500 Gilman Drive, La Jolla, CA 92093-0412, USA Department of Medicine, University of California San Diego, La Jolla, CA, USA Cardiac Biomedical Science and Engineering Center, University of California San Diego, CA, USA amcculloch@ucsd.edu.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: McCulloch
mesh_terms: D000200:Action Potentials; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy; D016280:Atrial Function, Right; D003198:Computer Simulation; D022062:Electrophysiologic Techniques, Cardiac; D005355:Fibrosis; D020342:Finite Element Analysis; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D011237:Predictive Value of Tests; D012032:Refractory Period, Electrophysiological; D013997:Time Factors; D014057:Tomography, X-Ray Computed
keywords: Atrial fibrillation; Computational modelling; FIRM; Focal impulse and rotor mapping; Phase mapping; Rotors