title: A comparison of noninvasive reconstruction of epicardial versus transmembrane potentials in consideration of the null space.
abstract: We compare two source formulations for the electrocardiographic forward problem in consideration of their implications for regularizing the ill-posed inverse problem. The established epicardial potential source model is compared with a bidomain-theory-based transmembrane potential source formulation. The epicardial source approach is extended to the whole heart surface including the endocardial surfaces. We introduce the concept of the numerical null and signal space to draw attention to the problems associated with the nonuniqueness of the inverse solution and show that reconstruction of null-space components is an important issue for physiologically meaningful inverse solutions. Both formulations were tested with simulated data generated with an anisotropic heart model and with clinically measured data of two patients. A linear and a recently proposed quasi-linear inverse algorithm were applied for reconstructions of the epicardial and transmembrane potential, respectively. A direct comparison of both formulations was performed in terms of computed activation times. We found the transmembrane potential-based formulation is a more promising source formulation as stronger regularization by incorporation of biophysical a priori information is permitted.
authors.affiliation: University for Health Informatics and Technology, Tyrol, Innsbruck, Austria. bernd.messnarz@umit.at
authors.forename: Bernd
authors.initials: B
authors.lastname: Messnarz
authors.forename: Michael
authors.initials: M
authors.lastname: Seger
authors.forename: Robert
authors.initials: R
authors.lastname: Modre
authors.forename: Gerald
authors.initials: G
authors.lastname: Fischer
authors.forename: Friedrich
authors.initials: F
authors.lastname: Hanser
authors.forename: Bernhard
authors.initials: B
authors.lastname: Tilg
mesh_terms: D000328:Adult; D000368:Aged; D001282:Atrial Flutter / Q000175:diagnosis / Q000503:physiopathology; D018780:Body Surface Potential Mapping / Q000379:methods*; D003198:Computer Simulation; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods; D006321:Heart / Q000294:innervation / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008564:Membrane Potentials; D008955:Models, Cardiovascular; D008959:Models, Neurological; D010496:Pericardium / Q000503:physiopathology*; D012849:Sinoatrial Node / Q000503:physiopathology; D009435:Synaptic Transmission; D014927:Wolff-Parkinson-White Syndrome / Q000175:diagnosis / Q000503:physiopathology