An optimal method for calculation of the frontal-plane vector from the data of the standard and unipolar limb leads

An optimal estimation of the frontal-plane cardiac vector (R, theta) was derived from the scalar ECG data of the standard and unipolar limb leads by the least square method which minimized the sum of squares of measurement errors of each lead data. The optimal vector was given by R = (Formula: see text) with V1, V2, V3, Vr, Vl and Vf being the measured values of the lead data. This estimation is optimal in that it coincides with the center of gravity of the vector obtained by using the two-lead data. A statistical evaluation of the reduction in measurement errors was performed.