title: Electrophysiological characteristics of junctional rhythm during ablation of the slow pathway in different types of atrioventricular nodal reentrant tachycardia.
abstract: BACKGROUND
  Junctional rhythm (JR) is commonly observed during radiofrequency (RF) ablation of the slow pathway for atrioventricular (AV) nodal reentrant tachycardia. However, the atrial activation pattern and conduction time from the His-bundle region to the atria recorded during JR in different types of AV nodal reentrant tachycardia have not been fully defined.
  
  
  METHODS
  Forty-five patients who underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia were included; 27 patients with slow-fast, 11 patients with slow-intermediate, and 7 patients with fast-slow AV nodal reentrant tachycardia. The atrial activation pattern and HA interval (from the His-bundle potential to the atrial recording of the high right atrial catheter) during AV nodal reentrant tachycardia (HA(SVT)) and JR (HA(JR)) were analyzed.
  
  
  RESULTS
  In all patients with slow-fast AV nodal reentrant tachycardia, the atrial activation sequence recorded during JR was similar to that of the retrograde fast pathway, and transient retrograde conduction block during JR was found in 1 (4%) patient. The HA(JR) was significantly shorter than the HA(SVT) (57 +/- 24 vs 68 +/- 21 ms, P < 0.01). In patients with slow-intermediate AV nodal reentrant tachycardia, the atrial activation sequence of the JR was similar to that of the retrograde fast pathway in 5 (45%), and to that of the retrograde intermediate pathway in 6 (55%) patients. Transient retrograde conduction block during JR was noted in 1 (9%) patient. The HA(JR) was also significantly shorter than the HA(SVT) (145 +/- 27 vs 168 +/- 29 ms, P = 0.014). In patients with fast-slow AV nodal reentrant tachycardia, retrograde conduction with block during JR was noted in 7 (100%) patients. The incidence of retrograde conduction block during JR was higher in fast-slow AV nodal reentrant tachycardia than slow-fast (7/7 vs 1/11, P < 0.01) and slow-intermediate AV nodal reentrant tachycardia (7/7 vs 1/27, P < 0.01).
  
  
  CONCLUSIONS
  In patients with slow-fast and slow-intermediate AV nodal reentrant tachycardia, the JR during ablation of the slow pathway conducted to the atria through the fast or intermediate pathway. In patients with fast-slow AV nodal reentrant tachycardia, there was no retrograde conduction during JR. These findings suggested there were different characteristics of the JR during slow-pathway ablation of different types of AV nodal reentrant tachycardia.
authors.affiliation: Cardiovascular Research Center and Division of Cardiology, Department of Medicine, National Yang-Ming University, Veterans General Hospital-Taipei, Taiwan, ROC. shlee@cm1.ethome.net.tw
authors.forename: Shih-Huang
authors.initials: SH
authors.lastname: Lee
authors.forename: Ching-Tai
authors.initials: CT
authors.lastname: Tai
authors.forename: Pi-Chang
authors.initials: PC
authors.lastname: Lee
authors.forename: Chern-En
authors.initials: CE
authors.lastname: Chiang
authors.forename: Jun-Jack
authors.initials: JJ
authors.lastname: Cheng
authors.forename: Kow-Chang
authors.initials: KC
authors.lastname: Ueng
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
authors.forename: Ming-Hsiung
authors.initials: MH
authors.lastname: Hsieh
authors.forename: Chin-Feng
authors.initials: CF
authors.lastname: Tsai
authors.forename: Chuen-Wang
authors.initials: CW
authors.lastname: Chiou
authors.forename: Wen-Chung
authors.initials: WC
authors.lastname: Yu
authors.forename: Jen-Yuan
authors.initials: JY
authors.lastname: Kuo
authors.forename: Hsuan-Ming
authors.initials: HM
authors.lastname: Tsao
authors.forename: Kun-Tai
authors.initials: KT
authors.lastname: Lee
authors.forename: Shih-Ann
authors.initials: SA
authors.lastname: Chen
mesh_terms: D000704:Analysis of Variance; D017115:Catheter Ablation / Q000379:methods*; D016009:Chi-Square Distribution; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome