1. A method of performing a medical procedure using a plurality of electrodes implanted within tissue of a patient, comprising: selecting a desired electrical current distribution on at least three active ones of the plurality of electrodes; generating an electrical energy perturbation on at least one of the plurality of electrodes; estimating a current-to-voltage relationship at each of the active electrodes based on the generated electrical energy perturbation, wherein the current-to-voltage relationship for each of the active electrodes takes into account electrical current flow through others of the active electrodes; determining an electrical voltage distribution on the active electrodes necessary to achieve the desired electrical current distribution on the active electrodes, wherein the electrical voltage distribution is based on the estimated current-to-voltage relationship; and conveying voltage-regulated electrical energy between the active electrodes and the tissue in accordance with the determined electrical voltage distribution.