title: Electrogram analysis at the His bundle region and the proximal coronary sinus as a tool to predict left atrial origin of focal atrial tachycardias.
abstract: OBJECTIVE
  Early activation at the His bundle (HB) region or proximal coronary sinus (CS) during focal atrial tachycardias (FATs) often necessitates biatrial mapping. Analysis of CS electrograms (EGMs) consisting of a near-field (N) component from CS musculature and a far-field (F) component from left atrial (LA) myocardium can uncover LA activation preceding right atrial (RA) activation. A similar pattern might be observed at the HB.
  
  
  RESULTS
  Eight patients underwent RA and LA pacing testing the hypothesis that N and F components originating from the RA and LA septum are present in the HB atrial EGM (Pacing group). In this group N preceded F (N-F sequence) in all, while F preceded N (F-N sequence) in seven of eight patients during RA and LA pacing, respectively. Twenty-seven patients with FAT demonstrating earliest activation at the HB or proximal CS during limited RA mapping were also studied (FAT group). Two observers analysed the EGMs at the earliest site during FAT. They found an N-F sequence in 17 (94%) and 16 (89%) of 18 RA FAT and an F-N sequence in seven (78%) and eight (89%) of nine LA FAT, respectively. The F-N sequence predicted the need for LA access with a sensitivity of 78 and 89% and a specificity of 94 and 89%.
  
  
  CONCLUSIONS
  Near-field and F components from RA and LA activation can be identified in the HB atrial EGM. Earliest atrial EGM analysis at the HB or CS can predict the need for LA access during FAT ablation.
authors: Second Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary. vtraykov@yahoo.com
authors: Vassil Borislavov
authors: VB
authors: Traykov
authors: Róbert
authors: R
authors: Pap
authors: Tchavdar Nikolov
authors: TN
authors: Shalganov
authors: Gábor
authors: G
authors: Bencsik
authors: Attila
authors: A
authors: Makai
authors: Rodrigo
authors: R
authors: Gallardo
authors: Gergely
authors: G
authors: Klausz
authors: Tamás
authors: T
authors: Forster
authors: László
authors: L
authors: Sághy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002036:Bundle of His / Q000503:physiopathology*; D017115:Catheter Ablation; D054326:Coronary Sinus / Q000503:physiopathology*; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013612:Tachycardia, Ectopic Atrial / Q000503:physiopathology* / Q000601:surgery