title: Noninvasive electrocardiographic imaging (ECGI): comparison to intraoperative mapping in patients.
abstract: OBJECTIVE
  Cardiac arrhythmias are a leading cause of death and disability. Electrocardiographic imaging (ECGI) is a noninvasive imaging modality that reconstructs potentials, electrograms, and isochrones on the epicardial surface from body surface measurements. We previously demonstrated in animal experiments through comparison with simultaneously measured epicardial data the high accuracy of ECGI in imaging cardiac electrical events. Here, images obtained by noninvasive ECGI are compared to invasive direct epicardial mapping in open heart surgery patients.
  
  
  METHODS
  Three patients were studied during sinus rhythm and right ventricular endocardial and epicardial pacing (total of five datasets). Body surface potentials were acquired preoperatively or postoperatively using a 224-electrode vest. Heart-torso geometry was determined preoperatively using computed tomography. Intraoperative mapping was performed with two 100-electrode epicardial patches.
  
  
  RESULTS
  Noninvasive potential maps captured epicardial breakthrough sites and reflected general activation and repolarization patterns, localized pacing sites to approximately 1 cm and distinguished between epicardial and endocardial origin of activation. Noninvasively reconstructed electrogram morphologies correlated moderately with their invasive counterparts (cross correlation = 0.72 +/- 0.25 [sinus rhythm], 0.67 +/- 0.23 [endocardial pacing], 0.71 +/- 0.21 [epicardial pacing]). Noninvasive isochrones captured the sites of earliest activation, areas of slow conduction, and the general excitation pattern.
  
  
  CONCLUSIONS
  Despite limitations due to nonsimultaneous acquisition of the surgical and noninvasive data under different conditions, the study demonstrates that ECGI can capture important features of cardiac electrical excitation in humans noninvasively during a single beat. It also shows that general excitation patterns and electrogram morphologies are largely preserved in open chest conditions.
authors.affiliation: Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio, USA.
authors.forename: Raja N
authors.initials: RN
authors.lastname: Ghanem
authors.forename: Ping
authors.initials: P
authors.lastname: Jia
authors.forename: Charulatha
authors.initials: C
authors.lastname: Ramanathan
authors.forename: Kyungmoo
authors.initials: K
authors.lastname: Ryu
authors.forename: Alan
authors.initials: A
authors.lastname: Markowitz
authors.forename: Yoram
authors.initials: Y
authors.lastname: Rudy
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis*; D018780:Body Surface Potential Mapping; D002304:Cardiac Pacing, Artificial; D003198:Computer Simulation; D004562:Electrocardiography; D006801:Humans; D007432:Intraoperative Period; D010496:Pericardium / Q000502:physiology*; D011184:Postoperative Period; D016276:Ventricular Function