title: Ablation of epicardial ventricular arrhythmias from nonepicardial sites.
abstract: BACKGROUND
  Idiopathic epicardial ventricular arrhythmias can be targeted from the coronary venous system or the pericardial space, the endocardium, or the aortic sinus cusps.
  
  
  OBJECTIVE
  The purpose of this study was to analyze systematically the contribution of ablation at sites other than the epicardium to eliminate an arrhythmia originating in the epicardium.
  
  
  METHODS
  In a consecutive patient series of 33 patients (14 women, age 51 ± 14 years, ejection fraction 51% ± 9%) with epicardial ventricular arrhythmias, mapping and ablation was performed via the cardiac venous system/pericardial space, the aortic sinus cusp, and the left ventricular endocardium. An arrhythmia was defined as epicardial if the earliest onset of activation and a matching pace-map (≥10/12 leads) were identified in the epicardium.
  
  
  RESULTS
  In 12/33 patients (36%), either an endocardial approach alone (n = 3) or a combined endocardial/epicardial (n = 6), cusp/endocardial (n = 1), or cusp/epicardial (n = 2) approach was required to eliminate the ventricular arrhythmias. In 10 of 33 patients (30%), epicardial ablation alone was effective in eliminating epicardial ventricular arrhythmias. Ablation was ineffective due to failure to reach the site of origin with the ablation catheter in 5 of 33 patients (15%), the site of origin was too close to an epicardial artery or the phrenic nerve in 3 patients (6%), and power delivery was insufficient in 3 patients (9%).
  
  
  CONCLUSIONS
  About one-third of epicardial arrhythmias require ablation from sites other than the epicardium to eliminate the arrhythmia focus.
authors.affiliation: Division of Cardiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Miki
authors.initials: M
authors.lastname: Yokokawa
authors.forename: Rakesh
authors.initials: R
authors.lastname: Latchamsetty
authors.forename: Eric
authors.initials: E
authors.lastname: Good
authors.forename: Aman
authors.initials: A
authors.lastname: Chugh
authors.forename: Frank
authors.initials: F
authors.lastname: Pelosi
authors.forename: Thomas
authors.initials: T
authors.lastname: Crawford
authors.forename: Krit
authors.initials: K
authors.lastname: Jongnarangsin
authors.forename: Hakan
authors.initials: H
authors.lastname: Oral
authors.forename: Fred
authors.initials: F
authors.lastname: Morady
authors.forename: Frank
authors.initials: F
authors.lastname: Bogun
mesh_terms: D017115:Catheter Ablation; D004562:Electrocardiography; D004699:Endocardium / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology / Q000601:surgery; D012850:Sinus of Valsalva / Q000503:physiopathology / Q000601:surgery; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome; D018879:Ventricular Premature Complexes / Q000503:physiopathology* / Q000601:surgery*