Abstract: A system is disclosed for controlling the charging of a rechargeable battery in an implanted human tissue stimulator by means of an external power source. Included in the stimulator are battery protection devices designed to sense the state of charge of the battery and limit the charging currrent amplitude so as not to exceed a selected maximum based on different criteria including battery state of charge signals from the implanted stimulator which are indicative of the current amplitude and battery state of charge from one of the protection devices are transmited to an external unit. Based on these signals the external unit is operated in one of a plurality of modes to cause the battery to be charged by a current with an optimum safe amplitude irrespective of determined failure of one or more of the battery protection devices.

Abstract: An implantable living tissue stimulator is described with a current conductive protective shield, to prevent the flow of currents to or from the stimulator circuitry via the electrically conductive body fluid. Also disclosed is an implantable living tissue stimulator of the rechargeable type in which the stimulator circuit components are surrounded by a pickup coil, designed to pick up an external magnetic field for recharging the power source, e.g., battery of the stimulator. One embodiment incorporates one or more ferrite slabs extending through the coil wound about the rest of the stimulator components, in order to increase the coil pick up efficiency and to divert the magnetic field from the stimulator metal components, such as a metal container in which the stimulator circuitry is hermetically sealed and thereby minimize the heating of the components and/or metal container.

Abstract: A myocardial lead for applying electrical pulses to a myocardium includes a relatively large electrode body of a metal, exhibiting high stress fatigue and corrosion resistance properties, a short stud of a metal containing platinum is partially inserted into the electrode body, with the stud portion extending out of the body defining the electrode pin. The stud is electron beam welded to the body. The myocardial lead also includes a distal wire, which consists of a plurality of flexible wire coils of the same metal as the electrode body and are covered by a flexible rubber sleeve. At one end, the wire coils pass through a cavity in the electrode body, with the coils' portion extending therefrom being wrapped around the electrode body and welded thereto. The distal wire extends to a source of electrical pulses. A platinum winding is wrapped around the electrode pin and is attached at one end to the electrode body.

Abstract: A unipolar living tissue stimulator of the implantable type with an outer plate electrode which in one embodiment consists of a flat metal plate slotted by slots to form a plurality of electrically conductive strips. Each strip is electrically in contact with any other strip through only a single path. The strips are dimensioned so that any substantially square or circular surface area on any strip is significantly smaller than the total conductive surface area of the plate. Consequently, the heating of the slotted plate due to an external alternating magnetic field is reduced significantly.

Abstract: A rechargeable tissue stimulating system with a telemetry controlled power source. A constant current power source acting through an induction coil externally located with respect to a living patient is used to induce current flow in a charging circuit located beneath the skin of the patient. The charging circuit, in turn, recharges a battery which powers an electronic generator used for applying electrical pulses to stimulate living tissue in order to maintain bodily functions in the patient. A telemetry circuit connected to the charging circuit provides a magnetic output signal controlling externally located means associated with the power source.