title: Atrial tachycardias adjacent to the phrenic nerve: recognition, potential problems, and solutions.
abstract: BACKGROUND
  Ablation of atrial tachycardias (AT) arising from the crista terminalis region (CT) can be complicated by phrenic nerve (PN) injury.
  
  
  OBJECTIVE
  This study sought to describe epicardial protection techniques to prevent PN injury from endocardial ablation of AT.
  
  
  METHODS
  Ablation was attempted in 4 patients with focal AT arising from the CT in whom conventional endocardial ablation was limited by PN proximity identified by capture during pacing.
  
  
  RESULTS
  Four women ages 20, 28, 30, and 31 years with structurally normal hearts presented with symptomatic ATs failing medical therapy. In the first patient, endocardial cryoablation was performed during superior vena cava (SVC) PN pacing. After acute success, AT recurred. Open surgical ablation was then performed, but AT was noninducible under anesthesia, and an anatomic ablation was performed. AT was abolished, but sinus node dysfunction required pacemaker implantation. In the subsequent 3 patients with AT adjacent to the right PN, protection of the PN was attempted by inserting a peripheral angioplasty balloon (2 patients) or steerable ablation catheter and sheath into the epicardial space between the PN and atrium. Endocardial radiofrequency ablation was successful in all 3 patients without PN injury.
  
  
  CONCLUSIONS
  Epicardial protection of the PN allowing for safe endocardial ablation of CT ATs is a feasible method of managing these challenging cases and seems to be preferable to surgery.
authors.affiliation: Cardiac Arrhythmia Service, Cardiovascular Division, Brigham & Women's Hospital, Boston, Massachusetts 02115, USA. drjoeclee@yahoo.com
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Lee
authors.forename: Daniel
authors.initials: D
authors.lastname: Steven
authors.forename: Kurt C
authors.initials: KC
authors.lastname: Roberts-Thomson
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Raymond
authors.forename: William G
authors.initials: WG
authors.lastname: Stevenson
authors.forename: Usha B
authors.initials: UB
authors.lastname: Tedrow
mesh_terms: D000328:Adult; D017115:Catheter Ablation / Q000009:adverse effects*; D003452:Cryosurgery; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000293:injuries; D005260:Female; D005471:Fluoroscopy; D006329:Heart Conduction System / Q000473:pathology / Q000601:surgery; D006801:Humans; D010791:Phrenic Nerve / Q000293:injuries* / Q000473:pathology; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D055815:Young Adult