Effects of tissue conductivity variations on the cardiac magnetic fields simulated with a realistic heart-torso model.

Cardiac magnetic fields with varying tissue conductivities are simulated. A high-resolution finite-element torso model composed of 19 tissue types and with a voxel resolution of 1.5 mm x 1.5 mm x 3 mm is used. It has a detailed description of tissue geometries and therefore is well suited for analysing the effects of tissue conductivities on the cardiac magnetic fields. The computed results show the greatest sensitivity of the magnetic fields to the changes in the conductivity of blood and myocardium, and less significant sensitivity to the conductivity of the lungs, muscle, fat and other tissues. These results are relevant to future modelling of magnetocardiograms and solving the inverse problem. They also emphasize the importance of careful modelling of the blood and heart regions, and suggest that less attention needs to be directed to bone or fat tissue.

[1]  B.M. Horacek,et al.  Effect of torso boundaries on electric potential and magnetic field of a dipole , 1988, IEEE Transactions on Biomedical Engineering.

[2]  G. Stroink,et al.  Magnetocardiographic functional localization using a current dipole in a realistic torso , 1991, IEEE Transactions on Biomedical Engineering.

[3]  K. Harumi,et al.  Distribution of action potential durations in the canine left ventricle. , 1984, Japanese heart journal.

[4]  J. Lehr,et al.  Finite element models of thoracic conductive anatomy: sensitivity to changes in inhomogeneity and anisotropy , 1994, IEEE Transactions on Biomedical Engineering.

[5]  M. Eslami,et al.  Introduction to System Sensitivity Theory , 1980, IEEE Transactions on Systems, Man, and Cybernetics.

[6]  F. Johnston,et al.  The electrical conductivity of the tissues near the heart and its bearing on the distribution of the cardiac action currents , 1943 .

[7]  David B. Geselowitz,et al.  Magnetocardiography: An Overview , 1979, IEEE Transactions on Biomedical Engineering.

[8]  A. van Oosterom,et al.  The magnetocardiogram as derived from electrocardiographic data. , 1990, Circulation research.

[9]  J. Nenonen.  Solving the inverse problem in magnetocardiography , 1994, IEEE Engineering in Medicine and Biology Magazine.

[10]  K Millar,et al.  The sequence of normal ventricular recovery. , 1972, American heart journal.

[11]  THE EFFECT OF TEMPERATURE AND FLOW ON THE SPECIFIC RESISTANCE OF HUMAN VENOUS BLOOD , 1953 .

[12]  S. Rush,et al.  Resistivity of Body Tissues at Low Frequencies , 1963, Circulation research.

[13]  B M Horácek,et al.  Computer model of excitation and recovery in the anisotropic myocardium. I. Rectangular and cubic arrays of excitable elements. , 1991, Journal of electrocardiology.

[14]  D. Durrer,et al.  Total Excitation of the Isolated Human Heart , 1970, Circulation.

[15]  Stuchly,et al.  DIELECTRIC PROPERTIES OF BIOLOGICAL SUBSTANCES–TABULATED , 1980 .

[16]  C R Johnson,et al.  A computer model for the study of electrical current flow in the human thorax. , 1992, Computers in biology and medicine.

[17]  K. Foster,et al.  Dielectric properties of tissues and biological materials: a critical review. , 1989, Critical reviews in biomedical engineering.

[18]  Yongmin Kim,et al.  On the contribution of volume currents to the total magnetic field resulting from the heart excitation process: a simulation study , 1996, IEEE Transactions on Biomedical Engineering.

[19]  Gulrajani Rm,et al.  Models of the electrical activity of the heart and computer simulation of the electrocardiogram. , 1988 .

[20]  L. J. Leon,et al.  The effect of torso geometry on magnetocardiographic isofield maps. , 1987, Physics in medicine and biology.

[21]  H. Schwan,et al.  Specific Resistance of Body Tissues , 1956, Circulation research.

[22]  Yongmin Kim,et al.  Computational studies of transthoracic and transvenous defibrillation in a detailed 3-D human thorax model , 1995, IEEE Transactions on Biomedical Engineering.

[23]  H. Schwan,et al.  THE CONDUCTIVITY OF LIVING TISSUES , 1957, Annals of the New York Academy of Sciences.

[24]  N. A. Coulter,et al.  Development of turbulence in flowing blood. , 1949, The American journal of physiology.

[25]  D. Geselowitz,et al.  Simulation Studies of the Electrocardiogram: I. The Normal Heart , 1978, Circulation research.

[26]  Herman P. Schwan,et al.  Electrical Properties of Body Tissues and Impedance Plethysmography , 1955 .

[27]  B M Horácek,et al.  Computer model of excitation and recovery in the anisotropic myocardium. II. Excitation in the simplified left ventricle. , 1991, Journal of electrocardiology.

[28]  R. Plonsey,et al.  The Effects of Variations in Conductivity and Geometrical Parameters on the Electrocardiogram, Using an Eccentric Spheres Model , 1979, Circulation research.

[29]  Yongmin Kim,et al.  An efficient tissue classifier for building patient-specific finite element models from X-ray CT images , 1996, IEEE Transactions on Biomedical Engineering.