title: Slow pathway ablation in patients with atrioventricular node reentrant tachycardia and a prolonged PR interval.
abstract: OBJECTIVE
  We sought to assess the safety and efficacy of selective slow pathway ablation using radiogfrequency energy and a transcatheter technique in patients with a prolonged PR interval and atrioventricular (AV) node reentrant tachycardia.
  
  
  BACKGROUND
  Although both fast and slow AV node pathways can be ablated in patients with AV node reentrant tachycardia, slow pathway ablation, by obviating the risk of AV block, appears to be safer. However, the safety and efficacy of selective slow pathway ablation using transcatheter radiofrequency energy in patients with a prolonged PR interval during sinus rhythm are unclear.
  
  
  METHODS
  The seven study patients with a prolonged PR interval (mean +/- SD 237 +/- 26 ms) comprised three women and four men with a mean age of 31 +/- 15 years. The slow pathway was targeted in all seven patients at the posterior/inferior interatrial septal aspect of the tricuspid annulus. Two patients presented with the uncommon variety of AV node reentrant tachycardia after initial fast pathway ablation; in the remaining five patients, the AV node reentrant tachycardia was of the common variety.
  
  
  RESULTS
  A single radiofrequency pulse at 30 W successfully abolished the slow pathway in both the anterograde and the retrograde direction in the two patients with uncommon AV node reentrant tachycardia. A mean of 5 +/- 3 radiofrequency pulses were required in the remaining five patients with reentrant tachycardia of the common variety. The postablation PR interval and AH interval remained unchanged. The shortest cycle length of 1:1 AV conduction was prolonged significantly (from 327 +/- 31 to 440 +/- 59 ms, p < 0.01, as was the AV node effective refractory period (from 244 +/- 35 to 344 +/- 43 ms, p < 0.01). During a mean follow-up interval of 20 +/- 6 months, no patient developed symptoms suggestive of AV node reentrant tachycardia or had evidence of second- or third-degree AV block.
  
  
  CONCLUSIONS
  These data suggest that the AV node slow pathway can be ablated in patients with AV node reentrant tachycardia who demonstrate a prolonged PR interval during sinus rhythm.
authors.affiliation: Electrophysiology Laboratory, Milwaukee Heart Institute, Sinai Samaritan Medical Center, Wisconsin.
authors.forename: J S
authors.initials: JS
authors.lastname: Sra
authors.forename: M R
authors.initials: MR
authors.lastname: Jazayeri
authors.forename: Z
authors.initials: Z
authors.lastname: Blanck
authors.forename: S
authors.initials: S
authors.lastname: Deshpande
authors.forename: A A
authors.initials: AA
authors.lastname: Dhala
authors.forename: M
authors.initials: M
authors.lastname: Akhtar
mesh_terms: D000293:Adolescent; D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology; D017115:Catheter Ablation; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*