title: Direct visualization of epicardial structures and ablation utilizing a visually guided laser balloon catheter: preliminary findings.
abstract: BACKGROUND
  Intrapericardial mapping and ablation can be utilized to target epicardial arrhythmic circuits. Current epicardial ablation strategies are associated with risk of damage to adjacent structures, including the coronary vasculature and phrenic nerves.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the feasibility of an investigational, visually guided laser balloon catheter for manipulation within the pericardial space, visualization of epicardial structures, and delivery of laser ablation lesions to the ventricular myocardium.
  
  
  METHODS
  Pericardial access was obtained in 4 anesthetized swine by subxyphoid puncture. The laser balloon catheter was introduced into the pericardial space via a deflectable sheath, and was manipulated to predefined regions in all animals. Visually guided laser ablation was performed on the ventricular myocardium, with post mortem examination of lesion size and depth.
  
  
  RESULTS
  The laser ablation catheter could be manipulated to all targeted regions in all animals. Associated structures, including epicardial coronary arteries and veins as well as an endocardial catheter in the left atrial appendage, were easily visualized. A total of 9 laser energy applications at varying power/time settings were performed. Ablation utilizing moderate (7-8.5 W) power produced relatively uniform lesions (diameter 5-12 mm, depth 6-9 mm), while high (14 W) power produced a visible "steam pop" with a large, hemorrhagic lesion (22 × 11 × 11 mm).
  
  
  CONCLUSIONS
  The investigational laser balloon catheter can be manipulated within the epicardial space, allowing for direct visualization of surrounding structures during ablation. Titration of laser power can be utilized to create moderate-sized ablation lesions while avoiding steam pops.
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: E Kevin
authors.initials: EK
authors.lastname: Heist
authors.forename: Conor
authors.initials: C
authors.lastname: Barrett
authors.forename: Francesco
authors.initials: F
authors.lastname: Perna
authors.forename: Stephan
authors.initials: S
authors.lastname: Danik
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Ruskin
authors.forename: Moussa
authors.initials: M
authors.lastname: Mansour
mesh_terms: D017222:Angioplasty, Balloon, Laser-Assisted / Q000295:instrumentation / Q000379:methods*; D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods; D010496:Pericardium / Q000033:anatomy & histology / Q000473:pathology* / Q000601:surgery*; D013552:Swine