title: Return cycle mapping after entrainment of ventricular tachycardia.
abstract: BACKGROUND
  The central common pathway, which is the target for ablation in reentrant ventricular tachycardia, can be localized by entrainment mapping techniques. However, localization of the pathway is not always possible because of the elevated pacing threshold and the low voltage and fractionated potentials at the pathway. We examined whether return cycle mapping after entrainment localizes the pathway without pacing at the pathway or recording the potentials from the pathway and determined the required electrode resolution to localize the pathway.
  
  
  RESULTS
  Epicardial mapping was performed with 253 unipolar electrodes during and after entrainment of 13 morphologies of ventricular tachycardia that were induced in dogs 4 days after infarction. The return cycle was calculated by subtracting the first activation time from the second activation time after the last stimulus and the return cycle distribution map was constructed for each stimulation site. The return cycle isochrones equal to the ventricular tachycardia cycle length converged on the lines of conduction block irrespective of the stimulation site, and the central common pathway was localized at the region between the intersections of the return cycle isochrones after entrainment from different stimulation sites. The potentials from the central common pathway were not required to localize the pathway, and the mapping accuracy did not change with or without analysis of the potentials from the pathway. According to the correlation between the electrode resolution and the mapping accuracy, an interelectrode distance of 8.5 mm was estimated as sufficient resolution for successful tachycardia termination during radiofrequency ablation guided by return cycle mapping.
  
  
  CONCLUSIONS
  Return cycle mapping after entrainment localizes the central common pathway without pacing at the pathway or recording the potentials from the pathway. This new mapping technique could improve the success rate of the ablative procedures.
authors.affiliation: Division of Cardiothoracic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: T
authors.initials: T
authors.lastname: Nitta
authors.forename: R B
authors.initials: RB
authors.lastname: Schuessler
authors.forename: M
authors.initials: M
authors.lastname: Mitsuno
authors.forename: C K
authors.initials: CK
authors.lastname: Rokkas
authors.forename: F
authors.initials: F
authors.lastname: Isobe
authors.forename: C S
authors.initials: CS
authors.lastname: Cronin
authors.forename: J L
authors.initials: JL
authors.lastname: Cox
authors.forename: J P
authors.initials: JP
authors.lastname: Boineau
mesh_terms: D000818:Animals; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D004562:Electrocardiography; D004566:Electrodes; D004594:Electrophysiology; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D008297:Male; D017180:Tachycardia, Ventricular / Q000503:physiopathology*