title: Non-invasive detection of conduction pathways to left atrium using magnetocardiography: validation by intra-cardiac electroanatomic mapping.
abstract: OBJECTIVE
  Alteration in conduction from right to left atrium (LA) is linked to susceptibility to atrial fibrillation (AF). We examined whether different inter-atrial conduction pathways can be identified non-invasively by magnetocardiographic mapping (MCG).
  
  
  RESULTS
  In 27 patients undergoing catheter ablation of paroxysmal AF, LA activation sequence was determined during sinus rhythm using invasive electroanatomic mapping. Before this, 99-channel magnetocardiography was recorded over anterior chest. The orientation of the magnetic fields during the early (40-70 ms from P onset) and later part (last 50%) of LA depolarization was determined using pseudocurrent conversion. Breakthrough of electrical activation to LA occurred through Bachmann bundle (BB) in 14, margin of fossa ovalis (FO) in 3, coronary sinus ostial region (CS) in 2, and their combinations in 10 cases by invasive reference in total of 29 different P-waves. Based on the combination of pseudocurrent angles over early and late parts of LA activation, the MCG maps were divided to three types. These types correctly identified the LA breakthrough sites to BB, CS, FO, or their combinations in 27 of 29 (93%) cases.
  
  
  CONCLUSIONS
  Magnetocardiographic mapping seems capable of distinguishing inter-atrial conduction pathways. Recognizing the inter-atrial conduction pattern may assist in understanding the pathogenesis of AF and identifying the subgroups for patient-tailored therapy.
authors.affiliation: Department of Cardiology Helsinki University Central Hospital, Helsinki, Finland. raija.jurkko@2me.fi
authors.forename: Raija
authors.initials: R
authors.lastname: Jurkko
authors.forename: Ville
authors.initials: V
authors.lastname: Mäntynen
authors.forename: Jari M
authors.initials: JM
authors.lastname: Tapanainen
authors.forename: Juha
authors.initials: J
authors.lastname: Montonen
authors.forename: Heikki
authors.initials: H
authors.lastname: Väänänen
authors.forename: Hannu
authors.initials: H
authors.lastname: Parikka
authors.forename: Lauri
authors.initials: L
authors.lastname: Toivonen
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D016275:Atrial Function / Q000502:physiology*; D018780:Body Surface Potential Mapping / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology*; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D053798:Magnetocardiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012849:Sinoatrial Node / Q000503:physiopathology