Abstract: A cardiac pacemaker having switching circuitry for dynamically re-assigning the electrical function of a plurality of electrodes coupled thereto. The pacemaker is provided with switching circuitry for allowing the sensing signals from a plurality of implanted electrodes may be selectively applied to sensing and detection circuitry in the pacemaker. Controller circuitry in the pacemaker controls the operation of the switching circuits and of a rheography current pulse generator such that a plurality of time slots are defined during a sensing interval. During successive time slots, a different electrical function may be assigned to the same electrode. Also disclosed is a method of operating such a pacing system.