title: Ablation of electrograms with an isolated, delayed component as treatment of unmappable monomorphic ventricular tachycardias in patients with structural heart disease.
abstract: OBJECTIVE
  We sought to evaluate the feasibility of identifying and ablating the substrate of unmappable ventricular tachycardia (VT).
  
  
  BACKGROUND
  Noninducible and nonstable VT cannot be ablated by the conventional approach.
  
  
  METHODS
  We studied 24 patients with documented monomorphic VT. Twenty-one patients had ischemic cardiomyopathy, two had nonischemic cardiomyopathy, and one had tetralogy of Fallot. Twelve patients had an implantable cardioverter-defibrillator. Conventional activation mapping was not possible in 18 patients: at least 1 of the clinical VTs or the clinical VT was not inducible in 12 patients, and VT was not tolerated in 6 patients. This group had experienced between 1 and 106 VT episodes in the month before the ablation procedure. Endocardial electroanatomic activation maps (Carto System) during sinus rhythm (SR) and right ventricular apex (RVA) pacing were obtained to define areas for which an electrogram displayed isolated, delayed components (E-IDC). These electrograms were characterized by double or multiple components separated by >/=50 ms.
  
  
  RESULTS
  One area of E-IDC was recorded in 20 patients, and 2 or more were recorded in 4 patients. In 23 patients, these areas were detected during RVA pacing; in only 14 during SR. An E-IDC area related to the clinical VT was identified in each patient. Ablation guided by E-IDC suppressed all but one clinical VT whose inducibility suppression was tested. During a follow-up period of 9 +/- 4 months, three patients had recurrences of the ablated VT and two of a different VT.
  
  
  CONCLUSIONS
  Electrograms with IDCs related to clinical VT can be identified in the majority of patients during RVA pacing. Radiofrequency ablation of E-IDC seems effective in controlling unmappable VT.
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: Esteban
authors.initials: E
authors.lastname: Glez-Torrecilla
authors.forename: Mercedes
authors.initials: M
authors.lastname: Ortiz
authors.forename: Julian
authors.initials: J
authors.lastname: Villacastín
authors.forename: Javier
authors.initials: J
authors.lastname: Fdez-Portales
authors.forename: Elena
authors.initials: E
authors.lastname: Sousa
authors.forename: Silvia
authors.initials: S
authors.lastname: del Castillo
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Perez de Isla
authors.forename: Javier
authors.initials: J
authors.lastname: Jimenez
authors.forename: Jesus
authors.initials: J
authors.lastname: Almendral
mesh_terms: D000328:Adult; D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods; D017115:Catheter Ablation / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006331:Heart Diseases / Q000150:complications / Q000601:surgery; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000150:complications / Q000453:epidemiology / Q000601:surgery*; D016896:Treatment Outcome