Evaluation method for EKG mapping

Claim 3

A method according to claim 1, wherein each parameter at each said electrode m, which parameter is assumed to be constant over the spherical surface of a sphere with radius r k , is obtained by calculating a voltage difference D m according to the formula ##EQU7## where: D m is the difference in voltages, U m is the projected voltage measured at each said electrode m, F m is the projection of a voltage vector calculated from Frank's EKG onto the lead axis defined by the electrical center of the heart and the position of each said electrode m, r m is the distance between each said electrode m and the electrical center of the heart, a m is an empirically determined correction factor for influence of the conductivity inhomogeneity of medium surrounding the heart, and change in location of the electrical center of the heart, the calculating of differences derived from the parameters is in accordance with the formula ##EQU8## where D m , D.sub.μ is the voltage difference at each said electrode m respectively μ; A.sub.μ is a weighting area element on the surface of the sphere which takes into consideration different mutual distances of the electrodes from each other, A M is the mean value of all A.sub.μ, and wherein p values of D.sub.μ are not used for the calculation of W m ; that belong to the p largest values of differences are calculated according to the formula ##EQU9## where Z m defines the p values of D m .

Claim 4

A method according to claim 1, wherein the parameter for each said electrode m assumed to be constant on the spherical surface of a sphere with radius r k is ##EQU10## for the m-th and μ-th electrode, respectively, the steps of calculating the parameters to obtain normalized difference D m according to the formula ##EQU11## said plotting of isointensity lines being of said differences, where U m and U.sub.μ are the voltage amplitudes at the m-th and μ-th electrodes, α m and α.sub.μ are the angles between the lead axis of the m-th and μ-th electrodes and Frank's voltage vector calculated from Frank's EKG projected onto the lead axis calculated from Frank's EKG projected onto the lead axis defined by the electrical center of the heart and the position of the m-th and μ-th electrode, A.sub.μ is a weighting area element on the projection surface for different mutual distances of the electrodes from each other, A M is the mean value of all A.sub.μ, r m and r.sub.μ are the distances of the m-th and μ-th electrodes from the electrical center of the heart, a m and a.sub.μ are empirically determined correction factors for influence of the conductivity inhomogeneity of medium surrounding the heart and change in location of the electrical center of the heart, and calculating cos α m and cos α.sub.μ from the formula ##EQU12## wherein the coordinates {R.sub.μ, S.sub.μ, T.sub.μ } of the μ-th electrode and the components {X, Y, Z} of the voltage vector are measured in accordance with Frank's lead system.