Abstract
A finite-difference computer model has been used to determine the potential distributions arising from a dipole current source aligned parallel to the axis of bounding cylinders. The radial position of this source had large and nonlinear influence on the potentials along the dipole axis. The accuracy of the computer simulation was established from comparison with an analytic solution of a simple geometry. Measurements using a conductance catheter in saline-filled cylinders also demonstrated the dependence of the conductance on the radial position. The dependence of the potential distribution on the radial position of the dipole places limits on the ultimate accuracy of the conductance catheter technique when used for the measurement of ventricular volume. Radial movement of the catheter within the ventricular cavity, resulting in changes in the potential distribution, could explain some artefacts that appear on volume recordings from the conductance catheter.
Similar content being viewed by others
References
Baan, J. Jong, T. T. A., Kerkhof, P. L. M., Moene, R. J., van Dijk, A. D., van der Velde, E. T. andKoops, J. (1981) Continuous stroke volume and cardiac output from intraventricular dimensions obtained with impedance catheter.Cardiovasc. Res.,15, 328–334.
Baan, J., van der Velde, E. T., de Bruin, H. G., Smeenk, G. J., Knoops, J., van Dijk, A. D., Temmerman, D., Senden, J. andBuis, B. (1984) Continuous measurement of left ventricular volume of animals and humans by conductance catheter.Circ.,70, 812–822.
Burkhoff, D., van der Velde, E., Kass, D., Baan, J., Maughan, W. L. andSagawa, K. (1985) Accuracy of measurement by conductance catheter in isolated, ejecting canine hearts.—Ibid.,72, 440–447.
Carré, B. E. (1961) The determination of the optimum accelerating factor for successive over-relaxation.Comput. J.,4, 73–78.
Heringa, A., Stegeman, D. F., Uijen, G. J. H. andde Weerd, J. P. C. (1982) Solution methods of electrical field problems in physiology.IEEE Trans.,BME-29, 34–42.
Hornbeck, R. W. (1975)Numerical methods. Quantum Publishers, New York.
McKay, R. G., Spears, J. R., Aroesty, J. M., Baim, D. S., Royal, H. D., Heller, G. V., Lincoln, W., Salo, R. W., Braunwald, E. andGrossman, W. (1984) Instantaneous measurement of left and right ventricular volume and pressure-volume realtionships with an impedance catheter.Circ.,69, 703–710.
Mur, G. andBaan, J. (1984) Computation of the input impedances of a catheter for cardiac volumetry.IEEE Trans.,BME-31, 448–453.
Patterson, R. P. (1985) Sources of the thoracic cardiogenic electrical impedance signal as determined by a model.Med. & Biol. Eng. & Comput.,23, 411–417.
Rankin, J. S., McHale, P. A., Arentzen, C. E., Ling, D., Greenfield, J. C. andAnderson, R. W. (1976) The three-dimensional dynamic geometry of the left ventricle in the conscious dog.Circ. Res.,39, 304–313.
Rush, S., Abildskov, J. A. andMcFee, R. (1963) Resistivities of body tissues at low frequencies.—Ibid.,12, 40–50.
Salo, R. W. andWallner, T. G. (1984) Computer modeling of intracardiac impedance plethysmography. Abstracts of IEEE/NSF Symposium on Biosensors, Los Angeles, California, 29–31.
Salo, R. W., Wallner, T. G. andPederson, B. D. (1986) Measurement of ventricular volume by intracardiac impedance: theoretical and empirical approaches.IEEE Trans.,BME-33, 189–195.
Spinelli, J. C. andValentinuzzi, M. E. (1986) Conductivity and geometrical factors affecting volume measurements with an impedancimetric catheter.Med. & Biol. Eng. & Comput.,24, 460–464.
van Oosterom, A., de Boer, R. W. andvan Dam, R. Th. (1979) Intramural resistivity of cardiac tissue.—Ibid.,17, 337–343.
Witwer, G. W., Trezek, G. J. andJewett, D. J. (1972) The effect of media inhomogeneities upon intracranial electrical fields.IEEE Trans.,BME-5, 352–362.
Woodard, J. C., Bertram, C. D. andGow, B. S. (1987) Right ventricular volumetry by catheter measurement of conductance.Pace,10, 862–870.
Young, D. (1954) Iterative methods for solving partial differential equations of elliptic type.Trans. Am. Math. Soc.,76, 92–111.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Woodard, J.C., Bertram, C.D. & Gow, B.S. Effect of radial position on volume measurements using the conductance catheter. Med. Biol. Eng. Comput. 27, 25–32 (1989). https://doi.org/10.1007/BF02442166
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02442166