Origins of the impedance change in impedance cardiography by a three-dimensional finite element model

• Published in: IEEE transactions on biomedical engineering Vol. 35; no. 12; pp. 993 - 1000
• Main Authors: Kim, D.W., Baker, L.E., Pearce, J.A., Won Ky Kim
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.1988; Institute of Electrical and Electronics Engineers
• Subjects: Biological and medical sciences; Blood; Boundary conditions; Cardiography; Cardiography, Impedance; Computer Simulation; Electric Conductivity; Electrocardiography. Vectocardiography; Electrodiagnosis. Electric activity recording; Finite element methods; Humans; Impedance; Investigative techniques, diagnostic techniques (general aspects); Laplace equations; Linear approximation; Mathematical Computing; Medical sciences; Models, Cardiovascular; Neck; Plethysmography, Impedance; Potential well; Thorax; Electrodiagnosis; Cardiovascular disease; Thorax; Impedance; Mathematical analysis; Biomedical engineering
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/10.8683

A three-dimensional finite-element model of the thorax and neck using eight-node trilinear hexahedron elements was constructed to investigate the impedance change associated with various physiological events during systole. A three-dimensional finite-element code was developed to solve the generalized Laplace equation with Dirichlet and homogeneous Neumann boundary conditions. The current in each element as well as potential at each node was calculated. The results suggest that an approximately linear relationship exists between the impedance change and blood volume change in the aorta. This is a promising result since the relationship helps explain the correlation between impedance cardiography and invasive techniques. Impedance changes due to blood volume changes in the aorta and ventricles, the lung-resistivity change, and the blood-resistivity change were calculated for standard impedance electrode configurations.< >