title: Ablation of posteroseptal and left posterior accessory pathways guided by left atrium-coronary sinus musculature activation sequence.
abstract: BACKGROUND
  While some posteroseptal and left posterior accessory pathways (APs) can be ablated on the tricuspid annulus or within the coronary venous system, others require a left-sided approach. "Fragmented" or double potentials are frequently recorded in the coronary sinus (CS), with a smaller, blunt component from left atrial (LA) myocardium, and a larger, sharp signal from the CS musculature.
  
  
  RESULTS
  Forty patients with posteroseptal or left posterior AP were included. The LA-CS activation sequence was determined at the earliest site during retrograde AP conduction. Eleven APs (27.5%) were ablated on the tricuspid annulus (right endocardial), 9 (22.5%) inside the coronary venous system (epicardial), and 20 (50%) on the mitral annulus (left endocardial). A "fragmented" or double "atrial" potential was recorded in all patients inside the CS at the earliest site during retrograde AP conduction. Sharp potential from the CS preceded the LA blunt component (sharp/blunt sequence) in all patients with an epicardial AP, and in 10 of 11 (91%) patients with a right endocardial AP. Therefore, 18 of 19 (95%) APs ablated by a right-sided approach produced this pattern. The reverse sequence (blunt/sharp) was recorded in 19 of 20 (95%) patients with a left endocardial AP.
  
  
  CONCLUSIONS
  During retrograde AP conduction, the sequence of LA-CS musculature activation-as deduced from analysis of electrograms recorded at the earliest site inside the CS-can differentiate posteroseptal and left posterior APs that require left heart catheterization from those that can be eliminated by a totally venous approach.
authors.affiliation: 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary. pap.paprobert@gmail.com
authors.forename: Róbert
authors.initials: R
authors.lastname: Pap
authors.forename: Vassil B
authors.initials: VB
authors.lastname: Traykov
authors.forename: Attila
authors.initials: A
authors.lastname: Makai
authors.forename: Gábor
authors.initials: G
authors.lastname: Bencsik
authors.forename: Tamás
authors.initials: T
authors.lastname: Forster
authors.forename: László
authors.initials: L
authors.lastname: Sághy
mesh_terms: D000293:Adolescent; D000328:Adult; D017115:Catheter Ablation / Q000379:methods*; D002648:Child; D054326:Coronary Sinus; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006325:Heart Atria; D006329:Heart Conduction System / Q000002:abnormalities* / Q000601:surgery*; D006346:Heart Septum / Q000601:surgery*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D016896:Treatment Outcome; D055815:Young Adult