An electronic electrode switching/selection circuit minimizes the number of feedthroughs from a pacer case to a pacer neck needed to connect with pacing lead electrodes that will be actively used during operation of a pacer. These feedthroughs can be electronically connected with the desired electrode by the physician either at the time of initial implantation or at any time subsequent thereto as may be required. The electronic connection to a feedthrough may be dedicated to a single feedthrough/electrode or electrode pair or the electrodes may be electronically sampled by circuitry in the pacer. The electrode switching/selection circuit may be located in the pacer neck, in an adapter between the pacer neck and a multielectrode lead, or in a multielectrode lead.
Preferably, zener protection diodes are also provided which are connected ahead of the pacing circuitry before or after the electrode switching/selection circuit. These zener protection diodes may be located in the pacer neck, in the adapter, or in the multielectrode lead, according to the location of the electrode switching/selection circuit.