title: Mapping multi-wavelet reentry without isochrones: an electrogram-guided approach to define substrate distribution.
abstract: OBJECTIVE
  A key mechanism responsible for atrial fibrillation is multi-wavelet reentry (MWR). We have previously demonstrated that ablation in regions of increased circuit density reduces the duration of, and decreases the inducibility of MWR. In this study, we demonstrate a method for identifying local circuit density using electrogram frequency and validated its effectiveness for map-guided ablation in a computer model of MWR.
  
  
  RESULTS
  We simulated MWR in tissues with variation of action potential duration and intercellular resistance. Electrograms were calculated using various electrode sizes and configurations. We measured and compared the number of circuits to the tissue activation frequency and electrogram frequency using three recording configurations [unipolar, contact bipolar, orthogonal closed unipolar (OCU)] and two frequency measurements (dominant frequency, centroid frequency). We then used the highest resolution electrogram frequency map (OCU centroid frequency) to guide the placement of lesions to high frequency regions. Map-guided ablation was compared with no ablation and random/blind ablation lesions of equal length. Electrogram frequency correlated with tissue frequency and circuit density as a function of electrode spatial resolution. Map-guided ablation resulted in a significant reduction in MWR duration (142 ± 174 vs. 41 ± 63 s).
  
  
  CONCLUSIONS
  Electrogram frequency correlates with circuit density in MWR provided electrodes have high spatial resolution. Map-guided ablation is superior to no ablation and to blind/random ablation.
authors.affiliation: University of Vermont College of Mathematics and Engineering, Burlington, VT, USA.
authors.forename: Bryce E
authors.initials: BE
authors.lastname: Benson
authors.affiliation: University of Vermont College of Mathematics and Engineering, Burlington, VT, USA University of Vermont College of Medicine, Burlington, VT, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Carrick
authors.affiliation: University of Vermont College of Medicine, Burlington, VT, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Habel
authors.affiliation: Boston University College of Engineering, Boston, MA, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bates
authors.affiliation: University of Vermont College of Mathematics and Engineering, Burlington, VT, USA University of Vermont College of Medicine, Burlington, VT, USA.
authors.forename: Jason H T
authors.initials: JH
authors.lastname: Bates
authors.affiliation: University of Vermont College of Medicine, Burlington, VT, USA.
authors.forename: Philipp
authors.initials: P
authors.lastname: Bielau
authors.affiliation: University of Vermont College of Medicine, Burlington, VT, USA peter.spector@uvm.edu.
authors.forename: Peter
authors.initials: P
authors.lastname: Spector
mesh_terms: D000200:Action Potentials; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D003198:Computer Simulation; D022062:Electrophysiologic Techniques, Cardiac; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery*; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008955:Models, Cardiovascular; D011237:Predictive Value of Tests; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome
keywords: Atrial fibrillation; Catheter ablation; Computer-based model; Electrophysiology mapping