title: Techniques to avoid atrioventricular block during radiofrequency catheter ablation of septal tachycardia substrates in young patients.
abstract: Radiofrequency catheter ablation (RFCA) has proven safe for most young patients, but the risk of inadvertent atrioventricular (AV) block remains. The purpose of this report is to describe techniques to avoid inadvertent AV block during effective RFCA in young patients with septal tachycardia substrates.
  
  
  METHODS
  The techniques included intubation and apnea during RFCA, coronary sinus pacing during RFCA to observe intact AV conduction during junctional ectopy, localizing the optimal His electrogram prior to RFCA, not ablating during tachycardia and titrating power output with temperature monitoring.
  
  
  RESULTS
  In the period January 1995-June 2001, RFCA of 424 tachycardia substrates was performed. A total of 217 consecutive septal tachycardia substrates are included in this report. Apnea eliminated a mean catheter tip displacement of 5.4 +/- 2.5 mm seen during respiration. No patient experienced transient or permanent complete AV block after any of the 217 substrate ablation procedures. All of the patients had normal PR intervals following ablation without development of any degree of AV block in 194 patients at latest follow-up. RFCA success for substrates with septal accessory pathways was 87/96 (91%), permanent junctional reciprocating tachycardia (PJRT) 15/16 (94%), typical atrioventricular node reentry tachycardia (AVNRT) 82/85 (96%), atypical AVNRT 6/7 (86%) and intra-atrial reentry tachycardia (IART) 10/13 (77%). Fluoroscopy time averaged 10.8 minutes. For patients with accessory pathway, 8 (7.9%) developed a recurrence.
  
  
  CONCLUSIONS
  Catheter stability is paramount to safe and effective RFCA in septal locations. Use of these techniques resulted in acceptable success rates and low recurrence rate for RFCA of septal tachycardia substrates while avoiding inadvertent AV block in these young patients.
authors.affiliation: Division of Cardiology, Children's Specialists, Children's Hospital San Diego, Department of Pediatrics, University of California, San Diego, California 92123, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pecht
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Maginot
authors.forename: Nicole K
authors.initials: NK
authors.lastname: Boramanand
authors.forename: James C
authors.initials: JC
authors.lastname: Perry
mesh_terms: D000293:Adolescent; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods*; D002648:Child; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005471:Fluoroscopy; D005500:Follow-Up Studies; D006327:Heart Block / Q000209:etiology* / Q000517:prevention & control*; D006801:Humans; D012008:Recurrence; D012307:Risk Factors; D012449:Safety; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery*; D013614:Tachycardia, Paroxysmal / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome