title: Ventricular fibrillation conduction through an isthmus of preserved myocardium between radiofrequency lesions.
abstract: BACKGROUND
  Selective local acceleration of myocardial activation during ventricular fibrillation (VF) contributes information on the interactions between neighboring zones during the arrhythmia. This study analyzes these interactions, centering the observations on an isthmus of myocardium between two radiofrequency (RF) lesions.
  
  
  METHODS
  In nine isolated rabbit hearts, a gap of preserved myocardium was established between two RF lesions in the anterolateral left ventricle (LV) wall. Before, during, and after increasing the spatial heterogeneity of VF by local myocardial stretching, VF epicardial recordings were obtained.
  
  
  RESULTS
  Local stretch in the anterior LV wall decreased the excitable window (17 ± 7 ms vs 26 ± 7 ms; P < 0.05) and increased the dominant frequency (DFr; 18.9 ± 5.0 Hz vs 15.2 ± 3.6 Hz; P < 0.05) in this zone, without changes in the non-stretched posterolateral zone (25 ± 4 ms vs 27 ± 6 ms, ns and 14.1 ± 2.7 Hz vs 14.3 ± 3.0 Hz, ns). The DFr ratio at both sides of the gap was inversely correlated to the excitable window ratio (R = -0.57; P = 0.002). Before (31% vs 26%), during (29% vs 22%), and after stretch suppression (35% vs 25%), the wavefronts passing through the gap from the posterolateral to the anterior LV wall were seen to predominate. The number of wavefronts that passed from the anterior to the posterolateral LV wall was related to the excitable window in this zone (R = 0.41; P = 0.03).
  
  
  CONCLUSIONS
  The VF acceleration induced in the stretched zone does not increase the flow of wavefronts toward the non-stretched zone in the adjacent gap of preserved myocardium. The absence of significant changes in the electrophysiological parameters of the non-stretched myocardium limits the arrival of wavefronts in this zone.
authors.affiliation: Service of Cardiology, Valencia University Clinic Hospital Incliva, Valencia, Spain. Francisco.J.Chorro@uv.es
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Chorro
authors.forename: Xavier
authors.initials: X
authors.lastname: Ibañez-Catalá
authors.forename: Isabel
authors.initials: I
authors.lastname: Trapero
authors.forename: Luis
authors.initials: L
authors.lastname: Such-Miquel
authors.forename: Francisca
authors.initials: F
authors.lastname: Pelechano
authors.forename: Joaquín
authors.initials: J
authors.lastname: Cánoves
authors.forename: Luis
authors.initials: L
authors.lastname: Mainar
authors.forename: Alvaro
authors.initials: A
authors.lastname: Tormos
authors.forename: Jose M
authors.initials: JM
authors.lastname: Cerdá
authors.forename: Antonio
authors.initials: A
authors.lastname: Alberola
authors.forename: Luis
authors.initials: L
authors.lastname: Such
mesh_terms: D000818:Animals; D002320:Cardiovascular Physiological Phenomena; D017115:Catheter Ablation; D006329:Heart Conduction System / Q000503:physiopathology*; D066298:In Vitro Techniques; D011817:Rabbits; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000601:surgery