US 3474791 A
Description (OCR text may contain errors)
6- 28, 1969 l. E. BENTOV MULTIPLE CONDUCTOR ELECTRODE Filed March 24, 1966 J5EE III/I0" jnuenz orx- Ill United States Patent 3,474,791 MULTIPLE CONDUCTOR ELECTRODE Itzhak E. Bentov, Belmont, Mass., assignor to Brunswick Corporation, a corporation of Delaware Filed Mar. 24, 1966, Ser. No. 537,031
Int. Cl. A61n 1/04; H01b 7/04 US. Cl. 128-418 11 Claims ABSTRACT OF THE DISCLOSURE An electrode having high break-resistance and flexibility and particularly suitable for implantation in a human body for conducting heart stimulating electrical currents from a suitable current supply to the heart muscle. The electrode structure comprises a plurality of flexible electrical conductors wrapped longitudinally and coaxially around a break-resistant, flexible, electrically conductive core, with the opposite ends of the conductors electrically connected to the core. The conductors and core are enclosed by an outer coaxial flexible insulating sheath arranged to expose the conductors at a point intermediate their ends.
This invention relates to electrical conductors and in particular to an electrode for use such as a cardiac pacer.
A number of devices have been developed heretofore for external electrical stimulation of a heart which has stopped beating or which is beating improperly as one which is fibrillating. An early example of such a device is that shown in Hyman et al. Patent No. 1,913,595. The present invention comprehends an improved electrode structure for conducting heart stimulating electrical currents from a suitable current supply to the heart muscle in such pacer apparatus.
Thus, a principal feature of the present invention is the provision of a new and improved electrode structure.
Another feature of the invention is the provision of such an electrode structure comprising an improved heart pacer electrode.
A further feature of the invention is the provision of such an electrode structure having new and improved construction providing long life at relatively low cost.
Still another feature of the invention is the provision of such an electrode structure providing improved circuit redundancy for improved maintained conductive functioning of the electrode.
A yet further feature of the invention is the provision of such an electrode structure having new and improved means for facilitating connection thereof to the heart muscle by the implanting surgeon.
Another feature of the invention is the provision of such an electrode structure having new and improved means for preventing deterioration thereof by body fluids and the like.
Another feature of the invention is the provision of such an electrode structure having a new and improved axial core construction providing improved functioning thereof.
A further feature of the invention is the provision of such an electrode structure wherein the core construction is formed of a plurality of extremely fine metal filaments.
Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:
FIGURE 1 is a fragmentary elevation of an electrode structure embodying the invention electrically connected between a suitable electrical current supply and a heart muscle;
FIGURE 2 is a fragmentary enlarged view of a portion of the electrode implanted in the heart muscle;
FIGURE 3 is a broken diametric section of the electrode prior to the installation of the stitching needle to one end thereof;
FIGURE 4 is a fragmentary, enlarged isometric view of a mid-portion of the electrode;
FIGURE 5 is a transverse section taken substantially along the line 55 of FIGURE 3;
FIGURE 6 is a fragmentary side elevation of the stitching needle attached to the end of the electrode with portions thereof shown in diametric section; and with a severing means shown fragmentarily for removing the stitching needle from the electrode upon completion of the implantation of the electrode in the heart muscle; and
FIGURE 7 is a schematic electrical wiring diagram of the circuit arrangement of the electrode.
In the exemplary embodiment of the invention as disclosed in the drawing, an electrode generally designated 10 is shown to comprise an elongated flexible structure having one end 11 connected by a suitable connector 12 to an electrical power supply 13 for providing suitable electrical current through the electrode 10 to a heart muscle, such as muscle 14. As shown in FIGURE 1, the opposite end 15 of the electrode is secured to the heart muscle 14 as by stitching 16. In the illustrated embodiment, a pair of electrodes 10 is provided for conducting the electrical current both to the heart muscle and back to the power supply 13; each of the electrodes is substantially identical and thus the following specific description thereof will be limited to a single electrode.
Referring now more specifically to FIGURES 2 through 5, the electrode 10 includes an axial elongated core 17 formed of a flexible, breakresistant material. In the illustrated embodiment, core 17 comprises a 300 end yarn formed of an electrically conductive material, such as 304 stainless steel filaments each having a cross-section of approximately 12 microns with the filaments having approximately 5 to 7 turns per inch twist therein. The filaments are impregnated with an elastomer, such as silicone rubber, which may be suitably cured as by heating in an oven at approximately 400 F. The core may be of suitable length, and in the illustrated embodiment, is approximately 28 inches long.
A silicone rubber sheath 18 is then provided over the core. As shown in FIGURE 3, a first end 19 of the sheath is spaced from one end 20 of the core to provide an exposed outer end 21 of the core, and the opposite end 22 of the sheath 18 is spaced from the opposite end 23 of the core. The end 23 may be twisted back upon itself to define an enlarged end suitable for connection thereto of a stitching needle, such as needle 24 shown in FIGURE 6. The silicone rubber sheath 18 may be provided on the yarn in any suitable conventional manner such as by extrusion thereonto, or by providing the sheath in a form of a tube which may be suitably cemented to the core after being drawn thereover. The sheath preferably is fixedly retained against axial slippage on the core.
A plurality of electrically conductive cables are wound helically about the sheath, herein a pair of cables 25 and 26 are provided degrees apart. Cable 25 has a first end 27 secured in electrical contact with the core 17, and cable 26 has a first end 28 secured in electrical contact with the core adjacent first cable end 27. Cable 25 has a second end 29 secured in electrical contact with the core end 23, and cable 26 has a second end 30 secured in electrical contact with the core end 23 adjacent cable end 29. Herein, cables 25 and 26 are formed of platinum and comprise seven strand cables wherein each strand has a diameter of approximately .001 inch.
The electrode further includes an outer sheath 31 having an outer end 32 coplanar with end 19 of sheath 18 and an inner end 32' spaced inwardly of the inner end 22 of the sheath 18 with the connections 29 and 30 of the platinum cables being disposed within the outer sheath 31 inwardly of the inner sheath end 22 and with the end 23 of the core extending outwardly therefrom. As best seen in FIGURES 2 and 3, the outer sheath 31 is provided with a gap 33 at a point outwardly of the inner sheath end 22. In the illustrated embodiment, the gap 33 may be approximately four inches outwardly of sheath ing to the right from gap 33 and portion 31b extending to the left therefrom. The sheath portions may be suitably provided as by extrusion thereof onto the subassembly of the core 17, sheath 18, and conductors and 26,
or by drawing of preformed tubular sheath structures onto the subassembly for positive retention thereon as by cementing. As shown in FIGURES 1 through 3, means are provided for indicating the location of the gap 33, herein in the form of a pair of black marks 34 and adjacent gap 33 on sheath 18 to be viewable through portions 31a and 31b respectively of sheath 31.
As indicated above, the electrode 10 may be provided with a stitching needle 24 secured to the end 23 of core 17 thereof for use by the surgeon in implanting the electrode suitably in the heart muscle .14. As best seen in FIGURE 6, the needle may comprise an arcuate needle having an attaching end 36 provided with an axial outwardly opening recess 37. An electrically conductive ferrule 38 is secured to the end 23 of the electrode core as by soldering and the core end 23 with the ferrule 38 secured thereto is retained in the recess 37 as by crimping of the needle end 36 illustratively shown at 39.
The electrode 10 may be utilized as follows. The surgeon may firstly install the power supply 13 under the patients skin in the abdomen or upper left chest cavity with the ends 11 of the electrode suitably secured to the connectors 12. The electrodes are drawn through the space between the internal organs of the patient and the rib cage to adjacent the heart. As shown in FIGURE 1, the distal ends of the electrodes are then stitched into the heart muscle 14 by means of the needle 24 to dispose the exposed cables 25 and 26 at gap 33 within the heart muscle thereby making electrical contact therewith. As shown in FIGURE 1, the ends of the electrodes are brought out from the heart muscle whereby the black marks 34 and 35 indicate to the surgeon the accurate centering of the gap 33 in the heart muscle. The exposed portions of the electrode adjacent the heart muscle may be suitably stitched thereto by surgical sutures 16. The needle 24 is removed from the end of the electrode as by cutting the end 15 by suitable means such as scissor blades as shown in FIGURE 6. The cut end of the electrode may be suitably capped if desired as by insulating cap 41. A loop is retained in the electrodes adjacent the heart to preclude tugging of the electrodes by the heart movements. In the illustrated embodiment, the heart muscle 14 is the left ventricle portion of the heart with the ends 15 of the electrodes extending toward the apex 42 thereof.
Illustratively, the power supply 13 may provide a current pulse of approximately 14 milliamperes at 6 to 7 volts and of approximately 2 millisecond duration. Referring to FIGURE 7, the current pulse is delivered to the exposed conductors 25 and 26 at gap 33 by three separate paths, thereby providing an improved long life characteristic of the electrode as a result of the circuit redundancy. More specifically, the current pulse may flow to the exposed portion of the wire 25 at gap 33 from the power supply 13 through the core portion 17 to the contact 4 27- and thence through the conductor 25. Similarly,'the current pulse may be delivered to the exposed portion of the conductor 26 at gap 33 by delivery of the current from power supply 13 through core 17 to the contact 28 and thence through the conductor 26. As the opposite ends of the conductors 25 and 26 are also electrically connected to the core 17 at points 29 and 30, a plurality of additional current flow paths to the exposed portions of the wires 25 and 26 is provided. More specifically, should a break in the wire 25 occur between the gap 33 and the point 27 the pulse could still be delivered to the portion of the conductor 25 at gap 33 through the core 17 to contact 30 and thence back to the exposed portion of the conductor at gap 33, as well as from the conductor 26 through contact 29 to contact 30. A similar supply of the current pulse to the exposed portion of conductor 26 at gap 33 would be provided in the event of a break in the conductor 26 between gap 33 and contact 28. Still further, should a pair of breaks occur, one each in conductors 25 and 26 between gap 33 and contact points 27 and 28, the current pulse could still nevertheless be delivered to the exposed portions of the conductors 25 and 26 at gap 33 by delivery thereof through the core 17 and thence through contact points 29 and 30 tothe exposed portions of the conductors. Still further, by virtue of the improved redundancy circuitry of the electrode, a break in one of the conductors 25 and 26 between the gap 33 and the contact point 29 or 30 thereof, in addition to breaks in each of the conductors between the gap 33 and the contacts 27 and 28 would still permit current flow to the other of the conductors in gap 33 through the core 17 and thence through the unbroken portion of the conductor extending backwardly to the gap 33.
Thus, electrode 10 provides an improved low cost, high reliability electrode adapted for use in such critical applications as heart pacer conductors.
While I have shown and described one embodiment of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the constructions and arrangement may be made Without departing from the spirit and scope of the invention as defined in the appended claims.
1. An electrode comprising: an elongated core of flexible, break-resistant, electrically conductive material; a plurality of flexible electrical conductors extending longitudinally of and coaxially about said core and electrically connected to said core at opposite end portions of said conductors; and an outer sheath of flexible insulating material coaxially about said core and electrical conductors and arranged to expose said electrical conductors at a point intermediate said opposite end portions of said conductors.
2. The electrode of claim 1 wherein said core is formed of a plurality of filaments having a diameter of under approximately one-half mil.
3. The electrode of claim 1 wherein said core comprises a yarn of metal filaments impregnated with an elastomer.
4. The electrode of claim 1 wherein said electrical conductors comprise a plurality of stranded cables.
5. The electrode of claim 1 wherein an intermediate sheath of flexible insulating material is disposed coaxially about said core, said electrical conductors being wrapped about said intermediate sheath.
6. The electrode of claim 1 wherein said conductors extend helically and are spaced from each other intermediate said end portions thereof.
7. The electrode of claim 1 wherein said electrical conductors comprise a pair of conductive elements extending helically degrees apart.
8. The electrode of claim 1 further including means adjacent said point at which said electrical conductors are exposed for indicating the location of the exposed portion References Cited of said electrical conductors.
9. The electrode of claim 1 further including a con- UNITED STATES PATENTS t 1 t 11 M h H t dt nd 1,687,912 10/1928 Wheeler 174-115 X iltezrgcrfe ec r1ca y a mec amca y connec e 0 one e 2,581,213 1952 pp 174 115 X 10. The electrode of claim 1 wherein said outer sheath 5 3,035,583 5/1962 Hlrsch et 128418 X is formed of two spaced portions defining between them 3,216,424 11/1965 Chadack 128-418 said point at which said electrical conductors are exposed. 3367339 2/1968 Sesslons 128418 11. The electrode of claim 10 wherein an intermediate sheath of flexible insulating material is disposed coaxially 1O WILLIAM KAMM Pnmary Exammer about said core, said electrical conductors being wrapped US, Cl, X R about said intermediate sheath. 174-114, 115