title: Novel use of atrial overdrive pacing to rapidly differentiate junctional tachycardia from atrioventricular nodal reentrant tachycardia.
abstract: BACKGROUND
  Distinguishing between junctional tachycardia (JT) and atrioventricular nodal reentrant tachycardia (AVNRT) is essential to minimize unnecessary catheter ablation and the risk of heart block during treatment of AVNRT.
  
  
  OBJECTIVE
  The purpose of this study was to investigate whether the tachycardia response to atrial overdrive pacing at a cycle length (CL) slightly shorter than tachycardia CL can differentiate between JT and AVNRT. We hypothesized that atrial overdrive pacing would transiently suppress JT but would entrain AVNRT.
  
  
  METHODS
  Twenty-one patients in whom AVNRT was induced and atrial overdrive pacing during either AVNRT or JT was attempted were included in the study. We predicted that, upon cessation of atrial overdrive pacing, an atrial-His-His-atrial (AHHA) response would identify JT and an atrial-His-atrial (AHA) response would identify AVNRT.
  
  
  RESULTS
  A total of 8 JT and 21 typical AVNRT were induced. Atrial overdrive pacing was attempted in all cases of JT and in 16 cases of AVNRT. An AHHA response was observed in 100% (8/8) of JT cases. In 2 cases of AVNRT, atrial overdrive pacing repetitively terminated the tachycardia. In the remaining patients with AVNRT, an AHA response was observed in 100% (14/14) of cases. When a response was able to be elicited, atrial overdrive pacing was 100% sensitive and 100% specific for differentiating JT from AVNRT.
  
  
  CONCLUSIONS
  Atrial overdrive pacing during tachycardia can rapidly differentiate JT from AVNRT, which can improve the safety and efficiency of catheter ablation of these arrhythmias.
authors.affiliation: Electrophysiology Section, Cardiovascular Division, Department of Medicine, Stony Brook University Medical Center, Stony Brook, New York, USA. roger.fan@stonybrook.edu
authors.forename: Roger
authors.initials: R
authors.lastname: Fan
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Tardos
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Almasry
authors.forename: Saverio
authors.initials: S
authors.lastname: Barbera
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Rashba
authors.forename: Sei
authors.initials: S
authors.lastname: Iwai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D003937:Diagnosis, Differential; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis*; D013613:Tachycardia, Ectopic Junctional / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D016896:Treatment Outcome