2001

^r5 The inverse problem may be solved by creating simplified models, which well represent the properties of the source and the conductor.

ą The activating cardiac cells act as source elements uirth current density J' ^ which produce two fields_

2 Fields: )

J'(Xy₁z,t)

'3 The clinical problem is: THE INVERSE PROBLEM

Electric field:

6 The equations of the electric and magnetic fields have two terms representing the contributions of

the SOURCE and the CONDUCTOR

4ucfO(r)= J J^;*V(-i-)dv +    (cj'-oj")<i>V(-p-) ♦ dS.

J

Dipole

Multiple dipole Multipole

V-* Trivial solution O* Finite homogeneous ^ Finite inhomogeneous

Clinical ECG lead systems are Solutions of the field eguations With certain source and conductor models

12- lead ECG VCG (Frank) Multiple dipole ECG

Magnetic field:

4 ltH(r )= J J ^;xV(y-)dv

Dipole

+

2j(v<>v(-f)xdś_j

J s.

Trivial solution

Multiple dipole ^ Finite homogeneous Multipole ^ Finite inhomogeneous

4    Which means^

To solve the source J' (x. y. z, from the detected fields ( $, H) The distribution of active tissue is the same function (x. y. z. t) Lead field theory provides the theoretical basis for solving the inverse problem

t)

8

In clinical MCG the same model can be used as in ECG

X YZ ABC

Unipositional

The lead systems detecting the electric and magnetic dipoles

have three orthogonal components

which have the following sensitivity distributions

FIELD

ELECTRIC

MAGNETIC

DIPOLEMOMENT

V*j')dv

SENSITIVfTY DISTRIBUTION

m

-łj

r xJ'dv