title: Activation patterns during selective pacing of the left ventricle can be characterized using noninvasive electrocardiographic imaging.
abstract: BACKGROUND
  Noncontact endocardial mapping allows accurate beat-to-beat reconstruction of the reentrant pathway of ventricular tachycardia and improves outcomes after ablation. Several studies support electrocardiographic imaging (ECGI) as a means of noninvasively outlining epicardial activation despite constraints of internal geometry. However, few have explored its clinical application. This study aims to evaluate ECGI during selective left ventricular (LV) pacing, relative to an invasive approach.
  
  
  METHODS
  Multisite pacing was performed within the left ventricles of 3 patients undergoing invasive procedures. Simultaneous recording of endocardial potentials using a noncontact multielectrode array and body surface potentials (BSP) using an 80-electrode torso vest was performed. A total of 16 recordings were made. The inverse solution was applied to BSP to reconstruct epicardial activation. Single-paced beats from real and virtual electrograms were used to construct 3-dimensional isochronal and isopotential maps. Endocardial and epicardial data were then superimposed onto a single geometry to allow quantitative comparison of activation foci.
  
  
  RESULTS
  Good correlation was observed between endocardial activation patterns and those reconstructed from BSP using ECGI. This was repeatedly demonstrated in all LV regions except for the septum (3 recordings). Epicardial isochronal maps were able to locate early and late activation to mean distances of 13.8 +/- 4.7 and 12.5 +/- 3.7 mm from endocardial data. Isopotential maps localized pacing sites with comparable accuracy (14 +/- 5.3 mm).
  
  
  CONCLUSIONS
  Body surface potentials and reconstructed epicardial activation patterns during LV pacing correlate well with endocardial data acquired invasively. The exception was during pacing of the septum. Although early results are encouraging, further quantitative data are required to fully validate and apply this noninvasive tool in the clinical arena.
authors.affiliation: Regional Medical Cardiology Centre, Royal Victoria Hospital, Belfast, Northern Ireland, United Kingdom. joshannon01@yahoo.co.uk
authors.forename: Heather Joanne
authors.initials: HJ
authors.lastname: Shannon
authors.forename: Cesar O
authors.initials: CO
authors.lastname: Navarro
authors.forename: Bernie A
authors.initials: BA
authors.lastname: Smith
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: McClelland
authors.forename: Ernest W
authors.initials: EW
authors.lastname: Lau
authors.forename: Michael J D
authors.initials: MJ
authors.lastname: Roberts
authors.forename: John M C
authors.initials: JM
authors.lastname: Anderson
authors.forename: Jeninifer A
authors.initials: JA
authors.lastname: Adgey
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D003952:Diagnostic Imaging / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000517:prevention & control*