US3472234A - Body organ electrode - Google Patents

Description

Oct. 14, 1969 H. N. TAcH|cK 3472234 BODY ORGAN ELECTRODE Filed Aug. 15. 1967 "'Qa Q '/////////////////////////////////////////////w United States Patent O 3,472,234 BODY ORGAN ELECTRODE Henry N. Tachck, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Filed Aug. 15, 1967, Ser. No. 660,661 Int. Cl. A61n 1/04, 1/36 U.S. Cl. 12S-418 5 Claims ABSTRACT OF THE DISCLOSURE An implantable electric power supply may be connected to an organ which is to be stimulated with a ne insulated helically wound cable. A stiff helical sleeve over an uninsulated end of the cable has a pointed tip and a keyengageable flattened convolution to facilitate screwing it into an organ with a stylet.

CROSS-REFERENCE TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION Pathological conditions of body organs, such as the heart, are now frequently palliated by stimulation with electric pulses from a power supply that is implanted in the body. In the early stages of the development of this procedure, the power supply was implanted at one site and uninsulated ends of conductors running from the supply were sutured into the organ to provide electrical connections. In the case of heart stimulation, this technique required open-chest surgery which has obvious disadvantages. In the above-cited application of J. G. Quinn, electrodes or conductors are proposed for obviating openchest surgery. In the Quinn application, at least the bare ends of the conductors are helical, stiff and sharply pointed so they may be screwed into the tissue of the organ. This is done by inserting a hollow needle into the thorax until its distal tip contacts the myocardium. Then the conductor is passed from the proximal to the distal end of the needle and screwed into the myocardium after which the needle is slid back off of the conductor. The proximal end of the conductor is then connected and sealed to the implanted power supply. Although this design resulted in simplification of the surgical procedure, it has the disadvantage of requiring that something more than a simple electrical plug-in connection be made to the implanted power supply during surgery.

SUMMARY OF THE INVENTION The electrodes of the present invention permit a new and simplified procedure of making electrical connections to an organ and to a power supply. One specie of the new electrode has two conductors extending from a plug that snaps on and is self-sealing to an implanted power supply. Each conductor comprises a cable of fine wire filaments and each cable is insulated and wound as a permanently set helix. The insulation on the helical cable is a thin coat- 3,472,234 Patented Oct. 14, 1969 ICC ing of Telion or the like, except that at. its distal end, it is uninsulated and made rigid. The rigid. end is helical, as is the cable, and it is sharply pointed. At least one convolution of the helix in the end region is deformed or out-of-round so that a fiat stylet may be admitted coaxially on the inside of the helix until it engages or keys with the deformed convolution. The stylet is then twisted to advance or screw the helical tip into the tissue of the organ.

The procedure may be performed exclusively through an incision or with a mediastinoscope, not shown, which has a tubular barrel and a pistol grip handle. The barrel is about three-fourths of an inch in diameter and is longitudinally slotted coextensive with its length. There is a light source in the handle and a small metal sheathed fiber optics bundle extending from the source to the end of the barrel to provide illumination at the distal end when it is inserted in a body cavity through an incision.

When the mediastinoscope barrel is inserted so that its distal end is in proximity to the heart, if that is the organ of interest, one helical conductor is admitted down the barrel until its pointed tip touches the organ. A flat Wire stylet is previously admitted between turns of the helix and advanced coaxially down its interior until they end of the stylet engages the deformed convolution of the helix. The stylet is then twisted to screw the tip of the conductor into the organ and the sylet is withdrawn. The tip becomes seized eventually by formation of brous tissue. The mediastinoscope is withdrawn after all conductors are attached, but it is not necessary to slide its barrel over the helical conductors and the connector because the conductors can be passed through the slot in the side of the barrel.

Objects of the invention are to provide a body implantable electrode: that obviates open chest surgery; that is easy to install; that reduces patient trauma; that is durable, exible and of loss mass; that effects a sound electrical connection with body tissue; and, that may be connected conveniently to an implanted organ stimulator power supply. How the foregoing and other more specific objects are achieved will appear in the ensuing specification which describes embodiments of the invention in reference to the drawing.

DESCRIPTION OF THE DRAWING FIGURE l is a perspective view of one type of the new body implantable electrode assembly;

FIGURE 2 is a horizontal section taken through the connector end or the left end of the electrode in FIG- URE l;

FIGURE 3 is an enlarged fragmentary perspective view of the helical, rigid distal end of the conductor with the end of the stylet inserted to illustrate how the helix may be screwed into an organ;

FIGURE 4 is a section taken on a line 4 4 in FIG- URE 3;

FIGURE 5 is a plan view of another embodiment of the invention; and,

FIGURE 6 is a partial vertical section taken through the connector or left end of the electrode assembly of FIGURE 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGURE l, the new electrode assembly comprises a molded connector plug 10l with a couple of connector pins 11 projecting from one end. The pins are surrounded by a metal shell 12 which has a flattened region 13 that compels proper alignment with a mating connector on an implantable electric power supply, not shown. The connector is essentially the same as the one described in the above-cited application of Fisher et al., and it will not be described in great detail herein because it is only incidental to the instant invention. Extending from the right end of connector body 10, as shown, are a pair of .silicone rubberinsulating tubes 14 from which a pair of helically wound insulated conductors 15- project. The interiors of tubes 14 are filled with a self-curing, flexible, medical grade silicone adhesive from the connector body to the points designated by the reference numeral 16. This construction excludes body fluid from the connector.

Additional details of connector may be seen in the sectional view of FIGURE 2, which shows that it has an outer silicone rubber sleeve 17 and an inner sleeve 18, the latter of which forms a passageway through which tubes 14 exit from the connector body. The region 19 and other silicone rubber interfaces are filled with silicone adhesive for excluding uids.

Conductor is an insulated cable made of many extremely fine silver-coated stainless steel filaments as described in the above-cited application of Fisher et al. The cable has a cross-sectional diameter of about .018 inch including its thin insulation coating. The thin flexible insulating coating may be Teon or other suitable insulating material about .001 to .002 inch thick and it is applied before the cable is wound as a permanently set helix. The distal end of the helix which lies within the limits of the bracket 20 in FIGURE 1 and which appears magnified in FIGURE 3, is not insulated so that the end 20 will conduct when it is screwed into an organ.

The distal end 20 will now be discussed in reference to FIGURES 3 and 4. In order to be screwed into tissue, the conductive distal tip must be rigid. This is accomplished preferably by swaging on the cable end a thin stainless steel tube 21 which is ground to a sharp point 22. About four convolutions of the cable are covered with tube 21 thereby producing a rigid end about one centimeter long measured along the axis of the helix. A few additional cable convolutions 23, shown stippled, adjacent the convolutions which are rigidified -by tube 21 are also uninsulated for the sake of flexibility and gradual stress transition. The few bare and flexible convolutions 23 may be screwed into the organ so that if a break occurs at the junction with the rigid part, there will still be conduction. Following these few convolutions 23, of course, the remainder of the convolutions have a Teflon or other insulation coating 30 back into connector 10.

One of the rigid convolutions in the end region has a at spot 24 imparted to it as can be seen in FIGURES 3 and 4. This deformation permits the helical conductor to be engaged internally with a correspondingly formed end of a stylet 2S. When the end of stylet 25 is keyed in the region of the deformed convolution 24, twisting of the stylet causes the pointed tip 22 of the rigid conductor end to screw into the organ. The stylet is ordinarily introduced coaxially inside the helical conductor through a convolution interspace that is remote from the distal end and then the stylet is advanced axially until its end keys with the deformed convolution in the rigid end of the conductor.

As indicated, tube 21 is swaged onto an uninsulated portion of the cable before it is wound as a helix. In a practical case, tube 21 has inside and outside diameters of 0.017 and 0.123 inch, respectively, and its length is sufficient to extend over four cable convolutions. The crosssection of the cable is normally a little larger than the inside diameter of the tube so the cable is stretched slightly to reduce its diameter while the tube is fit on. The inside and outside diameters of the helix convolution are approximately 0.046 and 0.078 inch, respectively. It should be understood that the end of the cable may be stiffened by means other than the metal tube such as by applying silver solder.

FIGURE 5 shows an alternative embodiment of the new electrode wherein only one helical conductor 1S is adapted for being connected directly to the organ which is to be stimulated. The second electrode for completing a circuit from the organ back to the power supply consists of several groups 26 of a plurality of turns of uninsulated cable that is wrapped around the connector tbody 10 as shown in FIGURE 5. As shown-in FIGURE 6, helical conductor 15 extends from a silicone insulatingY tube 14 as described in connection with the FIGUREl embodiment. The other bare conductor which is wrapped around the connector body emerges from a similar insulating tube 27 which terminates within the connector body. A straight part 28 of the cable conductor follows in parallelism with tube 14 to a hole 29 where it emerges from sleeve 18 and is wrapped around its outside as shown. The several groups 26 of cable turns constitute a large area electrode which compensates for the increased impedance that would otherwise result from the length of the return path through other body tissue from the point on the organ where the end of helical conductor 15 is screwed in.

In summary, an electrode has been described which permits making a quick and durable connection to an organ by merely screwing a helically shaped end into the organ with a stylet. The helical conductor is insulated and exible in the interspace between the organ and the surface of the body where an attachment plug facilitates rapid connection to a subcutaneously implanted electric power supply. The surgical procedure for attaching the electrode is less traumatic to the patient and merely involves admitting the electrode leads through a comparatively small incision or through a mediastinoscope, and after attachment, laying the conductors in a surface incision leading to the power supply and then suturing the incisions.

Although two embodiments of the invention have been described, such description is intended to be illustrative rather than limiting, for the invention may be variously embodied and is to be limited only by interpretation of the claims which follow.

I claim:

1. In a body implantable electrode assembly that includes a flexible insulated conductor projecting from a connector and wherein the distal end of the conductor is adapted for attachment to a body organ, the improvement which comprises:

(a) a conductor having its uninsulated distal end region formed as a rigid helix, and

(b) key engageable means on at least one convolution intermediate the ends of the rigid helix, whereby a slender key means that is admitted coaxially of the rigid helix may engage the key engageable means for screwing the helix into an organ.

2. The invention set forth in claim 1 wherein:

(a) said key engageable means constitute a deformation in at least one of the rigid convolutions.

3. The invention set forth in claim 1 wherein:

(a) said conductor comprises a flexible wire cable, and

(b) at least one convolution of said cable which is next in the proximal direction from said rigid distal end is uninsulated. Y

4. The invention set forth in claim 1 wherein:

(a) said conductor is a flexible wire cable, and

(b) said rigid helix comprises a thin metal tube means fit tightly on the distal end of the exible cable to stifen the same.

5. A body implantable electrode assembly comprising:

(a) an electrical connector and insulation encasing the connector,

(b) an insulated flexible conductor projecting at its proximal end from the connector and having its distal end formed as a rigid helix,

(c) key engageable means on at least one convolution intermediate the ends of the rigid helix, whereby a slender key means that is admitted coaxially of the rigid helix may engage the key engageable means for screwing the rigid helix into an organ,

(d) a second uninsulated conductor extending from the connector and emerging from the insulation, thereof,

(e) from its place of emergence, said second conductor being wound around said connector to form a large contact area electrode.

References Cited UNITED STATES PATENTS 2,890,266 6/ 1959 Ballmeer 339-256 X 3,216,424 11/1965 Chardack 128-4l8 3,253,595 5/1966 Murphy et al 12S- 418 3,348,548 10/ 1967 Chardack 12S-418 WILLIAM E. KAMM, Primary Examiner

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