title: Percutaneous epicardial mapping during ablation of difficult accessory pathways as an alternative to cardiac surgery.
abstract: OBJECTIVE
  The aim of this study was to define the role of percutaneous epicardial mapping for the ablation of previous failed ablation of accessory pathways.
  
  
  BACKGROUND
  Cardiac surgery is the only curative option for failed radiofrequency (RF) catheter ablation of accessory pathway (AP)-mediated tachycardias. We investigated a combined percutaneous epicardial and endocardial approach for failed AP ablations.
  
  
  METHODS
  We present our experience in a series of 6 cases (7 APs) with previous failed attempts at catheter ablation (median 2 attempts, range 1-4) and persistent symptomatic tachycardias. Endocardial mapping of the APs was performed using conventional techniques. Sites with local electrograms suggestive of AP location were selected. When initial endocardial mapping was not successful for ablation of the pathway, percutaneous transthoracic pericardial puncture was performed via a subxiphoid approach, and an ablation catheter was positioned at the epicardial aspect of the putative AP location for epicardial-endocardial electrogram comparison. Endocardial RF energy was applied to locations considered appropriate. Epicardial RF applications were delivered when endocardial applications failed. Coronary arteriography was performed to assess the proximity of coronary arteries to the ablation catheter.
  
  
  RESULTS
  APs were located in the right free wall (4 patients, 5 APs) and the right (1 patient) and left (1 patient) posteroseptal regions. In all patients, epicardial mapping assisted in identifying successful ablation sites. In 3 patients, the earliest atrial activation during orthodromic tachycardia was present in an epicardial electrogram. Successful AP ablation was achieved with an epicardial RF application in 2 patients, either alone or with simultaneous endocardial-epicardial delivery. In the remaining 4 patients, APs were successfully ablated endocardially after epicardial mapping. These patients represent 18% of all cases referred to our institution for ablation of previously failed accessory pathways (6/32 patients).
  
  
  CONCLUSIONS
  A combined endocardial-epicardial approach to mapping and RF ablation can facilitate successful endocardial ablation in most cases. In selected cases, APs can be ablated by epicardial delivery of RF. Epicardial mapping is an effective alternative to cardiac surgery for patients in whom prior attempts at AP ablation have failed.
authors.affiliation: UCLA Cardiac Arrhythmia Center, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Valderrábano
authors.forename: David A
authors.initials: DA
authors.lastname: Cesario
authors.forename: Sen
authors.initials: S
authors.lastname: Ji
authors.forename: Kevin
authors.initials: K
authors.lastname: Shannon
authors.forename: Isaac
authors.initials: I
authors.lastname: Wiener
authors.forename: Charles D
authors.initials: CD
authors.lastname: Swerdlow
authors.forename: Hakan
authors.initials: H
authors.lastname: Oral
authors.forename: Fred
authors.initials: F
authors.lastname: Morady
authors.forename: Kalyanam
authors.initials: K
authors.lastname: Shivkumar
mesh_terms: D000293:Adolescent; D000328:Adult; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D004699:Endocardium / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology*; D019233:Retreatment; D012189:Retrospective Studies; D013610:Tachycardia / Q000503:physiopathology / Q000601:surgery*; D017211:Treatment Failure