title: Non-invasive focus localization, right ventricular epicardial potential mapping in patients with an MRI-conditional pacemaker system - a pilot study.
abstract: BACKGROUND
  With the advent of magnetic resonance imaging (MRI) conditional pacemaker systems, the possibility of performing MRI in pacemaker patients has been introduced. Besides for the detailed evaluation of atrial and ventricular volumes and function, MRI can be used in combination with body surface potential mapping (BSPM) in a non-invasive inverse potential mapping (IPM) strategy. In non-invasive IPM, epicardial potentials are reconstructed from recorded body surface potentials (BSP). In order to investigate whether an IPM method with a limited number of electrodes could be used for the purpose of non-invasive focus localization, it was applied in patients with implanted pacing devices. Ventricular paced beats were used to simulate ventricular ectopic foci.
  
  
  METHODS
  Ten patients with an MRI-conditional pacemaker system and a structurally normal heart were studied. Patient-specific 3D thorax volume models were reconstructed from the MRI images. BSP were recorded during ventricular pacing. Epicardial potentials were inversely calculated from the BSP. The site of epicardial breakthrough was compared to the position of the ventricular lead tip on MRI and the distance between these points was determined.
  
  
  RESULTS
  For all patients, the site of earliest epicardial depolarization could be identified. When the tip of the pacing lead was implanted in vicinity to the epicardium, i.e. right ventricular (RV) apex or RV outflow tract, the distance between lead tip position and epicardial breakthrough was 6.0 ± 1.9 mm.
  
  
  CONCLUSIONS
  In conclusion, the combined MRI and IPM method is clinically applicable and can identify sites of earliest depolarization with a clinically useful accuracy.
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, Leyweg 275, 2545 CH, The Hague, The Netherlands. a.vandergraaf@hagaziekenhuis.nl.
authors.forename: A W Maurits
authors.initials: AW
authors.lastname: van der Graaf
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, Leyweg 275, 2545 CH, The Hague, The Netherlands.
authors.forename: Pranav
authors.initials: P
authors.lastname: Bhagirath
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, Leyweg 275, 2545 CH, The Hague, The Netherlands.
authors.forename: Jacques
authors.initials: J
authors.lastname: de Hooge
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, Leyweg 275, 2545 CH, The Hague, The Netherlands.
authors.forename: Hemanth
authors.initials: H
authors.lastname: Ramanna
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, Leyweg 275, 2545 CH, The Hague, The Netherlands.
authors.forename: Vincent J H M
authors.initials: VJ
authors.lastname: van Driel
authors.affiliation: Department of Cardiology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Natasja M S
authors.initials: NM
authors.lastname: de Groot
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, Leyweg 275, 2545 CH, The Hague, The Netherlands. mjw.gotte@hagaziekenhuis.nl.
authors.forename: Marco J W
authors.initials: MJ
authors.lastname: Götte
mesh_terms: D018780:Body Surface Potential Mapping / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000295:instrumentation / Q000379:methods; D010138:Pacemaker, Artificial; D010496:Pericardium / Q000503:physiopathology; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*
keywords: Body surface potential mapping; Computational cardiac electrophysiology; Inverse potential mapping; MRI-conditional pacemaker systems; Non-invasive imaging