The information content of the potential distribution generated by the heart increases considerably as the distance from the heart decreases. The mathematical recovery of epicardial and volume potentials from data recorded at the boundary of the conducting medium ("body surface data'') is of great interest since it can provide information on the cardiac electrical activity noninvasively. The mathematical procedure can be characterized by the following two steps: 1) determination of the epicardial potential from "body surface data'' (inverse problem). This result already yields valuable information. 2) reconstruction of the volume potential, given the computed epicardial potential and taking into account the insulating condition on the "body surface'' (direct problem). Measured potential data, during a heart beat, were obtained from an experimental set up in which an isolated, Langerdorff perfused, dog heart was placed in a cylindrical tank filled with physiological solution. By means of 600 electrodes regularly distributed in the tank, instantaneous potential values were recorded at the tank border, at 3cm from the tank border and on ideal surfaces surrounding the heart at 1. and 0.5 cm from the epicardium. Sets of potential maps, graphically displayed as equipotential lines on horizontal planes, were obtained from the measured potential values. The various sets of maps provided an overall picture of the volume potential for a sequence of instants during the ventricular activation and repolarization. Major attention was devoted both to the analysis of the gradient maps related to the inflow and outflow currents near the epicardial surface and to the activation sequence, displayed as isochrone maps, during the QRS. The experimental epicardial and volume potential distributions were compared with the computed data. The comparison shows that the computed potentials reproduce correctly the main features of the measured potentials, as revealed by the analysis of the positions of minima, maxima and breakthrough points. Comparable results were obtained by considering the activation sequence maps.
Cardiac Potential Distribution in a Volume Conductor: Comparison between Measured and Numerically Recovered Potential Values
S Tentoni
1990
Abstract
The information content of the potential distribution generated by the heart increases considerably as the distance from the heart decreases. The mathematical recovery of epicardial and volume potentials from data recorded at the boundary of the conducting medium ("body surface data'') is of great interest since it can provide information on the cardiac electrical activity noninvasively. The mathematical procedure can be characterized by the following two steps: 1) determination of the epicardial potential from "body surface data'' (inverse problem). This result already yields valuable information. 2) reconstruction of the volume potential, given the computed epicardial potential and taking into account the insulating condition on the "body surface'' (direct problem). Measured potential data, during a heart beat, were obtained from an experimental set up in which an isolated, Langerdorff perfused, dog heart was placed in a cylindrical tank filled with physiological solution. By means of 600 electrodes regularly distributed in the tank, instantaneous potential values were recorded at the tank border, at 3cm from the tank border and on ideal surfaces surrounding the heart at 1. and 0.5 cm from the epicardium. Sets of potential maps, graphically displayed as equipotential lines on horizontal planes, were obtained from the measured potential values. The various sets of maps provided an overall picture of the volume potential for a sequence of instants during the ventricular activation and repolarization. Major attention was devoted both to the analysis of the gradient maps related to the inflow and outflow currents near the epicardial surface and to the activation sequence, displayed as isochrone maps, during the QRS. The experimental epicardial and volume potential distributions were compared with the computed data. The comparison shows that the computed potentials reproduce correctly the main features of the measured potentials, as revealed by the analysis of the positions of minima, maxima and breakthrough points. Comparable results were obtained by considering the activation sequence maps.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
