title: Phase angle shift is a better determinant for catheter electrode contact with tissue compared to a catheter sensed electrogram.
abstract: Convention holds that the magnitude of an electrogram (EGM) recorded from an ablation catheter indicates proximity to the tissue and may be used to guide tip placement. The shift in capacitance (phase angle) as the electrode touches the tissue may be a better guide. We compared these two methods over a range of distances in close proximity to heart tissue. This study suggests that EGM is not a reliable predictor of proximity to tissue within a few millimeters of the surface. Thus, EGM alone should not be used to guide electrode placement for ablation, as a millimeter off the surface will shift a greater percentage of delivered energy to the blood pool rather than the target tissue. EGM should also not be used to gauge force of the catheter into tissue. Phase angle is a better predictor of both variables, but an optimal combination of predictors remains to be found.
authors.affiliation: Division of Cardiology and the Cardiovascular Research Institute, University of California San Francisco, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Everett
authors.forename: Israel
authors.initials: I
authors.lastname: Byrd
authors.forename: Emily
authors.initials: E
authors.lastname: Wilson
authors.forename: Jamie
authors.initials: J
authors.lastname: Skoglund
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Olgin
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000601:surgery; D001698:Biomedical Engineering; D017115:Catheter Ablation / Q000379:methods*; D004566:Electrodes; D055724:Electrophysiological Phenomena; D006352:Heart Ventricles / Q000033:anatomy & histology / Q000601:surgery; D006801:Humans; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D013552:Swine; D016277:Ventricular Function, Left