XY selectable lead assembly

An implantable cardiac stimulation lead system for use with a stimulation device including an implantable housing containing a pulse generator which emits stimulation pulses, the lead system comprising:

• a plurality of first electrodes formed on or in the lead body for delivering a stimulation pulse current to tissue;
• a plurality of second electrodes for returning to the stimulation device the stimulation pulse current after traversing the tissue;
• a matrix switching system;
• X electrical conductors extending between a proximal connector releasably coupled to the stimulating device and extending to the matrix switching system and connected thereto;
• and
• Y electrical conductors extending between the (or a) proximal connector releasably coupled to the stimulating device and extending to the matrix switching system and connected thereto;
• wherein the matrix switching system has a switching device to connect within the matrix switching system each of the Y electrical conductors to each single X electrical conductor and also to each of the second electrodes;
• wherein each of the switching devices is actuated by a corresponding pulse from the pulse generator applied to corresponding X and Y conductors connected thereto such that the total number of X and Y electrical conductors required is fewer than the number of the plurality of the second electrodes.