title: Double potentials at successful catheter ablation site of left-sided retrograde accessory pathway: mitral isthmus block or conduction through coronary sinus musculature.
abstract: BACKGROUND
  We studied three patients who had orthodromic atrioventricular reentrant tachycardia (AVRT) using left lateral accessory pathway (AP), with difficulty in identifying the earliest site of retrograde atrial activation.
  
  
  RESULTS
  Electrophysiological studies and radiofrequency ablation were performed in three patients with refractory AVRT (Case 1 was a 42-year-old woman, Cases 2 and 3 were a 52- and a 40-year-old man, respectively). During AVRT, a prolonged ventriculoatrial (VA) interval (100-180 ms) and nearly simultaneous excitation of both distal and proximal coronary sinus (CS) sites were observed. During both AVRT and ventricular pacing, double atrial potentials were recorded in all patients. Ablation of the mitral annular site showing double atrial potentials (with the first component being present just after the ventricular potential at the left lateral atrioventricular annulus) eliminated retrograde AP conduction. In Cases 1 and 2 the first component of the double potentials was atrial activation conducted through AP distal to mitral isthmus block and the second component was activation proximal to block that conducted turning around the left-sided pulmonary veins. In Case 3 the first component was CS musculature activation conducted through AP and the second component was left atrium activation via CS musculature.
  
  
  CONCLUSIONS
  In AVRT that has a long VA interval and difficulty in identifying the earliest site of retrograde atrial activation, two different mechanisms existed (mitral isthmus block and conduction through CS musculature). Careful mapping of double atrial potentials and continuous VA activation at the left lateral mitral annulus is essential for determination of a successful ablation site.
authors.affiliation: The Second Department of Internal Medicine, Faculty of Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan. fujiki@med.u-toyama.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Fujiki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Usuda
authors.forename: Koichi
authors.initials: K
authors.lastname: Mizumaki
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Abe
authors.forename: Jotaro
authors.initials: J
authors.lastname: Iwamoto
authors.forename: Tadao
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D000328:Adult; D017115:Catheter Ablation / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology* / Q000628:therapy*