title: Accuracy considerations in catheter based estimation of left ventricular volume.
abstract: Cardiac volume estimation in the Left Ventricle from impedance or admittance measurement is subject to two major sources of error: parallel current pathways in surrounding tissues and a non uniform current density field. The accuracy of volume estimation can be enhanced by incorporating the complex electrical properties of myocardium to identify the muscle component in the measurement and by including the transient nature of the field non uniformity. Cardiac muscle is unique in that the permittivity is high enough at audio frequencies to make the muscle component of the signal identifiable in the imaginary part of an admittance measurement. The muscle contribution can thus be uniquely identified and removed from the combined muscle - blood measurement. In general, both error sources are transient and are best removed in real time as data are collected. This paper reviews error correction methods and establishes that the relative magnitudes of the error concerns are different in small and large hearts.
authors.affiliation: Temple Foundation Professor of Electrical and Computer Engineering at the University of Texas at Austin, 1 University Station, TX 78712, USA. jpearce@mail.utexas.edu
authors.forename: John A
authors.initials: JA
authors.lastname: Pearce
authors.forename: John E
authors.initials: JE
authors.lastname: Porterfield
authors.forename: Erik R
authors.initials: ER
authors.lastname: Larson
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Valvano
authors.forename: Marc D
authors.initials: MD
authors.lastname: Feldman
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization / Q000379:methods*; D003217:Conductometry / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D051379:Mice; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*