title: Prevention of phrenic nerve injury during epicardial ablation: comparison of methods for separating the phrenic nerve from the epicardial surface.
abstract: BACKGROUND
  The proximity of the phrenic nerve (PN) to cardiac tissue relevant to arrhythmias may increase the risk of PN injury. Strategies for preventing PN injury in the pericardial space are limited.
  
  
  OBJECTIVE
  The purpose of this study was to compare methods for separating the PN from the epicardial surface in order to prevent PN injury.
  
  
  METHODS
  Eight patients referred for epicardial ablation of arrhythmias were enrolled in the study. All patients required ablation near the PN. Endocardial and epicardial access was obtained in all patients. A three-dimensional mapping system was used to guide mapping and ablation. All patients underwent epicardial catheter ablation. Pacing via the ablation catheter identified the location of the PN. In order to prevent PN injury, four new strategies were tested in each patient. We sought to increase the distance between the epicardium and the PN by (1) placing a large-diameter balloon between the nerve and the myocardium, (2) introducing saline in steps of 20 ml until PN capture was lost or blood pressure dropped below 60 mmHg, (3) introducing air until PN capture was lost or blood pressure dropped below 60 mmHg, or (4) introducing a combination of saline and air until PN capture was lost or blood pressure dropped below 60 mmHg.
  
  
  RESULTS
  At each step, epicardial pacing was performed to assess for PN stimulation. The combination of air and saline resulted in the greatest decrease of PN stimulation. Saline only failed in all cases. Air only and balloon placement were infrequently successful.
  
  
  CONCLUSIONS
  Controlled and progressive inflation of air and saline together with careful monitoring of hemodynamic parameters appears to be the best strategy for preventing PN injury during epicardial ablation. Placement of a large balloon in the appropriate location can be difficult.
authors: Texas Cardiac Arrhythmia Institute, St. David's Medical Center, Austin, Texas, USA.
authors: Luigi
authors: L
authors: Di Biase
authors: J David
authors: JD
authors: Burkhardt
authors: Gemma
authors: G
authors: Pelargonio
authors: Antonio
authors: A
authors: Dello Russo
authors: Michela
authors: M
authors: Casella
authors: Pietro
authors: P
authors: Santarelli
authors: Rodney
authors: R
authors: Horton
authors: Javier
authors: J
authors: Sanchez
authors: Joseph G
authors: JG
authors: Gallinghouse
authors: Amin
authors: A
authors: Al-Ahmad
authors: Paul
authors: P
authors: Wang
authors: Jennifer E
authors: JE
authors: Cummings
authors: Robert A
authors: RA
authors: Schweikert
authors: Andrea
authors: A
authors: Natale
mesh_terms: D001145:Arrhythmias, Cardiac; D017115:Catheter Ablation / Q000009:adverse effects*; D006801:Humans; D010496:Pericardium / Q000294:innervation* / Q000601:surgery; D010791:Phrenic Nerve / Q000293:injuries / Q000601:surgery*; D011446:Prospective Studies; D020196:Trauma, Nervous System / Q000209:etiology / Q000517:prevention & control*