title: Tachycardia-related channel in the scar tissue in patients with sustained monomorphic ventricular tachycardias: influence of the voltage scar definition.
abstract: BACKGROUND
  Endocardial mapping before sustained monomorphic ventricular tachycardia (SMVT) induction may reduce mapping time during tachycardia and facilitate the ablation of unmappable VT.
  
  
  RESULTS
  Left ventricular electroanatomic voltage maps obtained during right ventricular apex pacing in 26 patients with chronic myocardial infarction referred for VT ablation were analyzed to identify conducting channels (CCs) inside the scar tissue. A CC was defined by the presence of a corridor of consecutive electrograms differentiated by higher voltage amplitude than the surrounding area. The effect of different levels of voltage scar definition, from 0.5 to 0.1 mV, was analyzed. Twenty-three channels were identified in 20 patients. The majority of CCs were identified when the voltage scar definition was < or =0.2 mV. Electrograms with > or =2 components were recorded more frequently at the inner than at the entrance of CCs (100% versus 75%, P< or =0.01). The activation time of the latest component was longer at the inner than at the entrance of CCs (200+/-40 versus 164+/-53 ms, P< or =0.001). Pacing from these CCs gave rise to a long-stimulus QRS interval (110+/-49 ms). Radiofrequency lesion applied to CCs suppressed the inducibility in 88% of CC-related tachycardias. During a follow-up of 17+/-11 months, 23% of the patients experienced a VT recurrence.
  
  
  CONCLUSIONS
  CCs represent areas of slow conduction that can be identified in 75% of patients with SMVT. A tiered decreasing-voltage definition of the scar is critical for CC identification.
authors.affiliation: Department of Cardiology, Hospital General Universitario Gregorio Marañón, Madrid, Spain. arenal@doymanet.es
authors.forename: Angel
authors.initials: A
authors.lastname: Arenal
authors.forename: Silvia
authors.initials: S
authors.lastname: del Castillo
authors.forename: Esteban
authors.initials: E
authors.lastname: Gonzalez-Torrecilla
authors.forename: Felipe
authors.initials: F
authors.lastname: Atienza
authors.forename: Mercedes
authors.initials: M
authors.lastname: Ortiz
authors.forename: Javier
authors.initials: J
authors.lastname: Jimenez
authors.forename: Alberto
authors.initials: A
authors.lastname: Puchol
authors.forename: Javier
authors.initials: J
authors.lastname: García
authors.forename: Jesús
authors.initials: J
authors.lastname: Almendral
mesh_terms: D000368:Aged; D017115:Catheter Ablation; D002921:Cicatrix / Q000503:physiopathology; D022062:Electrophysiologic Techniques, Cardiac; D006801:Humans; D009203:Myocardial Infarction / Q000150:complications; D010138:Pacemaker, Artificial; D012008:Recurrence; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*