title: Configuration of unipolar atrial electrograms during electrically induced atrial fibrillation in humans.
abstract: BACKGROUND
  During atrial fibrillation (AF), the atrium is activated by multiple wavelets that continuously change in size and direction. The aim of this study was to correlate the temporal variation in AF electrogram configuration with the varying spatial patterns of activation.
  
  
  RESULTS
  In a group of 25 Wolff-Parkinson-White patients undergoing cardiac surgery, the free wall of the right atrium was mapped (244 points) during electrically induced AF. The unipolar electrograms recorded during 4 seconds of AF were classified into four categories: (1) single deflections, (2) short-double potentials, (3) long-double potentials, and (4) fragmented potentials. The proportion of these four types of electrograms during AF was as follows: singles, 77 +/- 12%; short-doubles, 7 +/- 3%; long-doubles, 10 +/- 7%; and fragmented, 6 +/- 4%. Electrogram morphology was an indicator for rapid uniform conduction (single potentials; positive predictive value [PPV] of 0.96), collision (short-double potentials; PPV of 0.33), conduction block (long-double potentials; PPV of 0.84), and pivoting points or slow conduction (fragmented potentials; PPV of 0.87). In type I, II, and III AF, the proportion of long-double potentials was 4 +/- 2%, 12 +/- 3%, and 18 +/- 7% (P < .05); the proportion of fragmented complexes was 2 +/- 2%, 6 +/- 3%, and 10 +/- 4% (P < .05), respectively. During electrically induced and self-terminating episodes of AF, no preferential anatomic sites for double or fragmented potentials were found in the right atrium.
  
  
  CONCLUSIONS
  The morphology of single unipolar electrograms during AF reflects the occurrence of various specific patterns of conduction. This might be used to differentiate between different types of AF and to identify regions with structural conduction disturbances involved in perpetuation of chronic AF.
authors.affiliation: Department of Physiology, Cardiology and Cardiopulmonary Surgery, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
authors.forename: K T
authors.initials: KT
authors.lastname: Konings
authors.forename: J L
authors.initials: JL
authors.lastname: Smeets
authors.forename: O C
authors.initials: OC
authors.lastname: Penn
authors.forename: H J
authors.initials: HJ
authors.lastname: Wellens
authors.forename: M A
authors.initials: MA
authors.lastname: Allessie
mesh_terms: D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation; D006348:Cardiac Surgical Procedures; D002648:Child; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D006329:Heart Conduction System; D006801:Humans; D008297:Male; D008564:Membrane Potentials; D008875:Middle Aged; D008955:Models, Cardiovascular; D014927:Wolff-Parkinson-White Syndrome / Q000503:physiopathology* / Q000601:surgery*