US3340493A - Body implantable electrical connector - Google Patents

Description

Sept. 5,- 1967 D. c. FISHER ETAL 3,340,493

BODY IMPLANTABLE ELECTRICAL CONNECTOR Filed July 20, 1965 all 6 II E;

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FIG. 2

v ATTORNEY United States Patent 3,340,493 BODY IMPLANTABLE ELECTRICAL CONNECTOR David C. Fisher and Hugh MacDonald Forman, Brookfield, Wis., assignors to General Electric Company, a corporation of New York Filed July 20, 1965, Ser. No. 473,451

' 1 Claim. (Cl. 339-61) ABSTRACT OF THE DISCLOSURE A conductor that is insulated with silicone rubber terminates in a plug which is received in a socket that is recessed in a metal tube having a flared mouth. The tube is encircled by a silicone rubber ring. The silicone rubber insulation on the plug slips over the metal tube to make radially stressed seals with the flare and the tube. A concentric outer silicone rubber sheath surrounds the inner insulation and increases sealing force due to its elasticity. The outer sheath passes over the ring to form another radially stressed seal.

This invention relates to a self-sealing electrical connector that is intended primarily for connecting surgically implanted conductive leads between an organ of the body and an implanted electric power supply.

The invention may be used, for example, to connect an organ stimulator such as an artificial electronic cardiac pacemaker power supply with leads that connect to a subjects heart. One type of conductive lead assembly with which the new connector may be used, is illustrated in the co-pending application of the instant inventors, Ser. No. 473,403, which was filed on the same date and has the same assignee as this application.

It has been the custom to make permanent connections between implanted power supplies and their leads because of skepticism about corrosion and short-circuiting that might result if body fluids entered a connector. Consequently, thoracic surgeons when performing a cardiac implant were required to locate the power supply in an incision in one part of the body and then pull up the free ends of the lead through a passageway in the tissue in order to connect the free ends to the heart through an intercostal opening in the thoracic cavity. On some occasions, in order to avoid placing too much tensile stress on the delicate leads, the power supply itself was pulled from an incision in the thorax to its permanent site remote therefrom. It is easy to see that these procedures are more traumatic than desirable tov the patient and are quite inconvenient to the surgeon.

A further disadvantage of leads that are connected permanently to the power supply is that the heart is stimulated artifically immediately after the free ends of the lead wires are attached to it, whereas it is often desired to have the time at which stimulation is initiated under more complete control of the surgeon. This disadvantage follows from the fact that implanted power supplies are usually not provided with a switch that would permit their being turned on and off by external means.

Another matter to be considered is that in some cases artificial stimulation of an organ is not needed immediately but should be provided for to the extent possible during the major surgery so that if an emergency occurs which would indicate stimulation, it can be put into effect with maximum ease and minimum delay. A desirable preparatory step would be, of course, to implant the conductive leads before the major incision is closed in which case the power supply itself might be implanted later and connected while the patient is under local anesthesia.

In any event, most implantable power supplies depend on sealed-in batteries as a source of electric energy and these are often not rechargeable from outside the patients body. This necessitates periodic removal and replacement of the device with one having fresh batteries. A capability for disconnecting and connecting the replacement power supply with the implanted leads without disturbing them and without extensive surgery has obvious advantages.

The present invention is directed to securing the abovenoted advantages and to overcoming the noted disadvantages by providing a reliable, self-sealing connector assembly for body implantable devices.

More specific objects are to provide a connector: that may be used without adhesives or sealants; that may be repeatedly and easily attached and detached but which is,

nevertheless, secure in the body; that depends to a large extent on radial pressure to effect sealing; that has more than one sealed joint; and, that is small and compatible with the body.

How the foregoing and other objects are achieved will be apparent from time to time in the more detailed description of an illustrative embodiment of the invention which follows.

In general terms, the new connector assembly is characterized by a male conductive connector into which the end of insulated conductive leads are permanently sealed. A female connector that is permanently sealed in an implantable power supply is adapted to receive the male connector for closing the electric circuit. A first elastic sheath that surrounds the insulated conductors and is sealed around them extends over the male connector part to a point that is short of the end of the male part. An additional elastic sleeve is fastened with adhesive concentrically with the end of the sheath and is a little longer than the latter. The power supply is provided with an elastic ring that is permanently sealed about the base of the female connector. The female connector part has a radially flared lip. Thus, when the connectors are plugged together, the elastic inner sheath efiects a radial seal on the flared lip and on the outside surface of the female connector and the outer concentric elastic sleeve eifects a similar radially compressive seal with the outside of the ring. Thus, three sealing surfaces in series are produced in a preferred embodiment of the invention.

A more detailed description of the invention will now be set forth in reference to the drawing in which:

FIGURE 1 is a front view of an implantable power supply which is joined with a fragment of a lead assembly by means of the new self-sealing connector assembly;

FIGURE 2 shows the new connector assembly in crosssection and separated from the power supply; and,

FIGURE 3 shows the new connector assembly in crosssection and in sealing engagement with the power supply.

FIGURE 1 shows the outline of a power supply 1 in approximately actual size. Its thickness, in an actual case, may be about three-fourths of an inch. This unit may be located at some distance from the organ that is to be stimulated while the subject is ambulatory. Although it is not pertinent to the instant invention, power supplies of this type usually contain an oscillatorwhich has an output pulse rate of about 70 pulses per minute at around three volts if it is used for cardiac stimulation. The power supply usually includes long life batteries which drive the oscillator and are encapsulated with it in epoxy resin. There may be intervening moisture and insulating barriers but the exterior of the power supply is usually coated with silicone rubber.

The self-sealing connector is generally designated by the reference numeral 2 and it is seen to be joined with a section of conductive lead 3. Details of the latter may be seen in the co-pending application of the instant inventors which is cited above.

Patented Sept. 5, 1967 Refer now to FIGURE 2 where it may be seen that the connector assembly 2 comprises a metal shell 4 which has a diametrically reduced portion 5 to which is admitted an end of an insulated conductive lead 6. In reality, there may be a pair of insulated leads 6 inserted in reduced portion 5 of the shell and the ends of the leads may be sealed with a room temperature vulcanizing silicone rubber adhesive which is not particularly identified. Bare wires from conduetors 6 connect with insulated connector prongs which are not shown but are located inside of metal shell 4. The surface of the latter may be plated with gold for reducing the probability of corrosion.

Metal shell 4 is surrounded tightly by an elastic tubular sheath 7 which is preferably made of a body compatible silicone rubber. Sheath 7 may be adhered to the outside of metal shell 4 with silicone adhesive in a band surrounding the shell in the region marked with the reference numeral 8. Because there is no adhesive at the interface between shell 4 and sheath 7 below the point where reference numeral 9 is applied, the elastic wall of sheath 7 is capable of being expanded radially outward below this point.

Adhered on the outside of sheath 7 inthe region 10 is a concentric elastic sleeve 11 which, it will be observed, is preferably a little longer than sheath 7 and slightly curved at its lower edges 12, when detached, as a result of inherent elastic stress. Outer sleeve 11 is also preferably made of medical grade silicone rubber.

In FIGURE 2 it may be seen that the top of the power supply has sealed in it a cylindrical metal shell 13 which is preferably gold-plated and formed with a flared lip 14 near its top. Shell 13 is of suficient internal size to admit metal shell 4 and efiect an electrical connection by suitable conductive prongs which are not shown but which may extend inside shell 4 and be adapted to register in suitable sockets within shell'13. A ring of silicone rubber 15 is located on tubular shell 13 and adhered thereto and to the top of power supply 1 with medical grade silicone adhesive.

In FIGURE 3 is may be seen how a series of three radially compressive seals are formed when the connector is plugged in. The first seal is formed along an axial and circumferential surface between the interior of sleeve 11 and the peripheral exterior of ring 15. The second seal is formed between the interface of sheath 7 and the periphery of shell 13 as can be seen by the deformation of the ends of these parts in the drawing. The third seal is formed between circumferential lip 14 and the interior of sheath 7. Because of the sharpness of lip 14, a seal of especially high unit stress is formed between it and sheath 7.

It may be observed that the outer elastic sleeve 11 generates the principal radial force for all of the radial seals and that the seals have the property of increasing in efiiciency with time. This results from the fact that silicone rubber flows slightly when it is under compressive stress so as to fill even the minutest cavities or surface irregularities. In addition, there is apparently a superficial molecular migration from one silicone rubber surface to another and this results in sealing almost as effectively as if an adhesive were used between surfaces such as the interior of sleeve 11 and the exterior of ring 15 in FIGURE 3,

In any event, use of the seal in the body tissue environ- 'ment has demonstrated its efiicacy.

It should be observed that no reliance is placed upon axial or endwise compressive forces for sealing. This means that even though the lead assembly is placed in tension by movements of the body muscles,"the efliciency of the seals will not be affected.

When the above described lead assembly is implanted in the body in expectation that a power supply may have to be attached later, it is desirable to prohibit entry of body fluids in the connector end of the lead. This may be done by slipping over the open end of outer sleeve 11, a thin tightly fitting piece of silicone tubing, not shown, which serves as a cap and has one of its end pinched and sealed together. It is not necessary to apply any adhesive to the joint between thecap and sleeve 11 becausethe molecular migration or attraction property of silicone rubber which was mentioned above causes a sound seal to be created. Nevertheless, this cap may be pelled off without damaging the surface of outer sleeve 11 when the connector is ready for use.

. Although specific materials and a preferred construction of a self-sealing body implantable electrical connector has been described, such description is to be considered illustrative rather than limiting, for the invention may be variously embodied and is to be limited only'by interpretation of the claim which'follow.

It is claimed:

A self-sealing electrical connector assembly for joining a conductive lead with an electric power source that is implantable in a living body comprising: a

(a) a first electrical connector including ametal tubular component that has one endpermanently sealed 'in the power'source and an end remote therefrom flared toform a radially projecting lip,

(b) an elastic silicone rubber ring sealed around the tubular component away from the lip,

(c) a conductive lead and a second electrical connector attached thereto for being inserted in the first connector to complete an electric circuit,

(d) an elastic silicone rubber sheath substantially coaxial with said lead and extending axially along the second connector,

(e) an elastic silicone rubber sleeve adheredat one end to said sheath and surrounding said second connector substantially coextensive with-the sheath,

(f) whereby when said connectors are joined together the inside of said sheath develops radial .pressure seal joints with the lip and periphery of the tubular component of the first connector and said sleevedevelops a radial pressure seal joint with said ring.

References Cited UNITED STATES PATENTS 4/1918 Van Deventer 339-61 8/ 1956 Richards 339-94

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