THE ABSOLUTE VOLTAGE AND THE LEAD VECTOR OF WILSONS CENTRAL TERMINAL

The absolute potential value of Wilson's central terminal was calculat ed at 2 msec intervals during a cardiac cycle in 60 clinical cases. St arting from the body surface potential data at 128 thoracic locations, the effect of immersion of the body into an infinite conductor on the surface potential was calculated to obtain values with reference to z ero potential at infinity. The conductivity of the outside medium was then made to approach zero. Comparison of the result with the original map showed nearly a constant shift of the potential, corresponding to the voltage of Wilson's terminal. In addition, the cardiac vector was calculated as the first approximation of the cardiac electromotive fo rce and the lead vector of Wilson's terminal was obtained in order tha t the scalar product of the cardiac vector and the lead vector approxi mated the observed voltage of Wilson's terminal. The results indicate that the voltage of the Wilson electrode depended on the surface volta ge with a peak value near the maximal QRS force in most of the cases. The peak voltage of Wilson's terminal was either positive or negative, and was 0.15 mV in absolute value on average. Voltage variations of W ilson's terminal during a cardiac cycle were 0.20 mV as an average of all cases. The voltage of Wilson's terminal also depended on the direc tion of the equivalent cardiac vector. The lead vector of Wilson's ter minal was found to be directed superiorly in most of the cases. The av erage magnitude of the lead vector of Wilson's terminal was 0.097 Ohm/ cm, which corresponded to about 1/4 of that of lead I.