Electrode lead assembly for implantable devices and method of preparing

Abstract

An implantable electrode lead assembly for coupling an electrical stimulator pulse generator to an internal organ and a method for preparing such an assembly, the electrode lead assembly including a coiled conductor wound in the form of a helix about a central axis. An electrical conductor is encapsulated within a coaxially disposed flexible cylindrical sleeve, with the sleeve including separate inner and outer tubular elements. The inner tubular element is fabricated from a semi-conductive silicone rubber having a resistivity of less than about 130 ohm-cm., and with the outer tubular element comprising an electrically insulative silicone rubber, with both tubular elements having the property of expanding upon exposure to certain solvents or other mediums. The preparation operations utilize the expansion characteristic to form a unitary lead assembly. The arrangement is such that in the finished lead assembly upon fracture of the electrical conductor means, the inner semi-conductive tubular element acts as a back-up conductor which will provide a conductive path so as to continue delivering reasonably normal or reasonably effective stimulator pulses from the pulse generator through the lead assembly and to the conductive electrode tip or tips.