title: Discriminating atrial flutter from atrial fibrillation using a multilevel model of atrioventricular conduction.
abstract: BACKGROUND
  The discrimination between atrial flutter (AFlu) and atrial fibrillation (AFib) can be made difficult by an irregular ventricular response owing to complex conduction phenomena within the atrioventricular (AV) node, known as multilevel AV block. We tested the hypothesis that a mathematical algorithm might be suitable to discriminate both arrhythmias.
  
  
  OBJECTIVE
  To discriminate AFlu with irregular ventricular response from AFib based on the sequence of R-R intervals.
  
  
  METHODS
  Intracardiac recordings of 100 patients (50 patients with AFib and 50 patients with AFlu) were analyzed. On the basis of a numerical simulation of variable flutter frequencies followed by 2 levels of AV block in series, a given sequence of R-R intervals was analyzed.
  
  
  RESULTS
  Although the ventricular response displays absolute irregularity in AFib, the sequences of R-R intervals follow certain rules in AFlu. We find that using a mathematical simulation of multilevel AV block, based on the R-R sequence of 16 ventricular beats, a stability of atrial activation could be predicted with a sensitivity of 84% and a specificity of 74%. When limiting the ventricular rate to 125 beats/min, discrimination could be performed with a sensitivity of even 89% and a specificity of 80%. In cases of AFlu, the atrial cycle length could be predicted with high accuracy.
  
  
  CONCLUSIONS
  On the basis of the electrophysiological mechanism of multilevel AV block, we developed a computer algorithm to discriminate between AFlu and Afib. This algorithm is able to predict the stability and cycle length of atrial activation for short R-R sequences with high accuracy.
authors.affiliation: Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany. Electronic address: eberhard.scholz@med.uni-heidelberg.de.
authors.forename: Eberhard P
authors.initials: EP
authors.lastname: Scholz
authors.affiliation: Faculty of Mathematics, University of Magdeburg, Magdeburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Kehrle
authors.affiliation: Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Vossel
authors.affiliation: Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hess
authors.affiliation: Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany; DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
authors.forename: Edgar
authors.initials: E
authors.lastname: Zitron
authors.affiliation: Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany; DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Katus
authors.affiliation: Faculty of Mathematics, University of Magdeburg, Magdeburg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Sager
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy; D001282:Atrial Flutter / Q000503:physiopathology* / Q000628:therapy; D001283:Atrioventricular Node / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D011379:Prognosis
keywords: AV node; Atrial fibrillation; Atrial flutter; Atrioventricular conduction; Multilevel AV block