Patent ID: 8620458

Claim:
A system for providing electrical stimulation to cardiac tissue and for sensing electrical signals generated by said tissue, the system comprising: an implantable medical lead comprising: a helix electrode extendable and retractable relative to a distal tip of the lead; an electrically conductive mapping collar disposed at said distal tip; and an electrical connector assembly carried by a proximal end of the lead, the electrical connector assembly comprising a first terminal connected to the helix electrode and a second terminal separately connected to the mapping collar; and an IMD comprising: a receptacle for receiving the connector assembly of the medical lead, the receptacle enclosing electrical contacts adapted to be engaged by the terminals on the electrical connector assembly; electrical IMD circuitry; and a switch network interposed between said IMD circuitry and said receptacle contacts, said switch network being configurable to connect to the electrical IMD circuitry the helix electrode only, the collar electrode only, the series combination of the helix electrode and collar, or the parallel combination of the helix electrode and collar, whereby a range of electrode impedances is made available.