Heart Stimulator System For Rapid Implantation And Removal With Improved Integrity

Abstract

Disclosed is a quick connect-disconnect heart stimulator system including a catheter assembly. The catheter assembly is screwed into the remainder of the system and not only effects positive mechanical coupling, but also positive and resilient electrical connection and fluid-tight sealing, all in one quick operation. The system also permits inserting and removing a catheter positioning stylet without disconnecting the catheter from the remainder of the system with self sealing material preventing entry of body fluids after the stylet is withdrawn.

Description

Artificial heart stimulations, or pacers are employed to supplement or replace the material pacing electrical activity of a heart which is functionally impaired due to one or more diseased conditions. The most widely used stimulators at present comprise an implantable body containing pacing circuitry and an endocardial catheter connected to the pacing circuit on one end with the other end introduced through a large vein into the right ventricle of the heart. This conventional heart stimulator is powered by a battery of mercury cells which have a useful life of about 18-24 months, after which the stimulator body must be replaced. Also, catheter lead connections for attachment to the stimulator are difficult to make and require auxiliary tools and materials to effect sound electrical contact and reasonable sealing against body fluids.

With the development of a heart stimulator which employs a rechargeable long-lived nickel-cadmium cell, such as those disclosed in copending patent applications with Ser. Nos. 154,492, filed 6/18/71 and 267,114, filed 6/28/72, now abandoned in favor of continuation-in-part application Ser. No. 464,441, filed Apr. 26, 1974, many of the disadvantages of the conventional stimulators were overcome.

It is the principal object of this invention to provide an arrangement for quick connect-disconnect of a catheter to a heart stimulator body which has the features of high, reliable contact pressure and fluid-tight, sealed connection.

It is another object of this invention to provide a sealed heart stimulator system including a catheter which permits introduction into the catheter when connected to the remainder of the system of a positioning stylet through a body of self-sealing material which prevents entry of body fluids into the catheter when the stylet is withdrawn.

Other objects, features and advantages of this invention will be apparent from a consideration of the following detailed description in conjunction with the drawings which are briefly described as follows:

FIG. 1 is a pictorial view of a heart stimulator system according to this invention;

FIG. 2 is a partly sectioned elevational view of a catheter assembly and stimulator assembly as assembled into the system according to this invention;

FIG. 3 is a partly sectioned side view of a system in accordance with FIG. 2;

FIG. 4 is a partial section view taken along the lines 4--4 in FIG. 2;

FIG. 5 is a partial section view taken along the lines 5--5 in FIG. 2;

FIG. 6 is a partial section view taken along the lines 6--6 in FIG. 7; and

FIG. 7 is a partial section view of the heart contacting end of a catheter.

FIG. 1 shows an implantable stimulator system comprising a stimulator body or assembly 10, and a catheter assembly 20. Body 10 comprises a main enclosure 11 in which an open cavity 11A is defined in an upper corner surface thereof. Main enclosure 11 houses a power cell and pulse generating pacer circuitry and a cover 12 which is welded to enclosure 11. Catheter 30 has a proximal electrode 31 and a distal tip electrode 32, and defines an axially extending interior space 30A. This particular catheter is a dual polarity type--a single polarity type would have only a distal tip electrode.

The construction of the catheter assembly 20, which includes both a catheter 30 and a catheter support means 20A, is best understood from a description of the manner in which each part is assembled with reference to FIGS. 2-5. Catheter support means 20A is assembled as follows. Connector arm 204 is welded transversely across the upper end of a male connector nut 201, adjacent one end of arm 204. Center contact member 202 is inserted through male connector nut 201 and held in position while insulator 203 is molded in place using an epoxy material. A catheter mounting or terminal block 205 is slipped over the top of member 202 and positioned upon arm 204, over insulator 203, and opposite male connector 201, with arm 204 therebetween. Terminal mounting block 205 is provided with a transverse passageway 205A therethrough. A plurality of silicone rubber membranes 206 are inserted in catheter mounting block 205 in passageway 205A and then stylet funnel 207 is screwed in place. This subassembly is then fastened to contact member 202 by set screw 208 (FIG. 3).

To join catheter support means 20A with catheter 30 to form catheter assembly 20, the proximal end of catheter 30 is slipped through clip 209 which is then welded at its flanges (FIG. 5) to connector arm 204 so that catheter interior space 30A and passageway 205A are coaxial and in communication at the catheter connector end. Distal coil lead 304, which comprises three coiled wires, is inserted in a boss on catheter mounting block 205. The three wires of this lead are led out through three slots (e.g., 205A, see FIG. 4) and sequentially welded to catheter mounting block 205. Proximal coil lead 302, which comprises four coiled wires, is then attached to proximal connector arm 204 by sequentially welding the four wire ends to separate points on arm 204.

This assembled structure is then placed in a mold and potted in an epoxy material 208. Finally, the potted connector is placed in another mold and coated with silicone rubber 209A, completing assembly 20.

The connector contact portion of body 10 is assembled in this manner. Ceramic insulator 106 is placed into the cavity 11A in body 10, preferably defined by metal support 101. In the lowermost portion of cavity 11A, spaced from the entrance thereof, terminal cap 105 is welded to terminal stud 104, connected in turn to the aforementioned circuitry, and then two contact wires 108 are welded to terminal cap 105. This assembly is inserted through support 101 and glass insulating ring 103 is cast in place, creating a hermetic seal. Ceramic insulator 106 is then cemented in place. Belleville springs 109 are inserted, followed by O-ring 110, and then contact pad 107 is placed into the cavity. Contact wires 108 are welded to contact pad 107. Finally, female connector 111 is mounted in the cavity occupying the entrance thereof, and welded in place, and O-ring 112 is inserted in a recess in female connector 112. Connector 111 is oriented so that connectors 201 and 111 will upon being united define an axis which is transverse to passageway 205A and space 30A. After this assembly operation body 10 is inserted in a mold and covered with silicone rubber 102.

At this point male connector 201 and female connector 111 can be joined by screwing male connector nut 201 into female assembly 111. The molded body of connector 20 provides a lever arm for tightening male assembly nut 201 against the beveled contact portion of female connector 111. O-ring 112 is compressed to aid in keeping body fluids out of the connector. A second resilient O-ring 110 is provided within cavity 11A coaxially with connector 111, in contact with the cavity wall (as defined by insulation 106), and having an annular thickness at least large enough to permit the male connector conductive portion to engage it. As male connector nut 201 screws into female connector 111, contact member 202 encounters contact pad 107 and an annular knife edge 202A provided on the leading end of contact member 202 bites into the top surface of contact pad 107 to provide intimate metal-to-metal contact. Belleville springs resist the movement of contact pad 107 to provide a high contact pressure, but also to absorb any cumulative tolerance errors. At the same time, resilient O-ring 110 is compressed to help seal out any body fluids which may enter this part of the connector. The same Bellville springs also support O-ring 110, to aid in compressibly sealing the electrical connection. The two contact wires provide connection redundancy, and the lower part of terminal pad 107 has flat sides to prevent rotation as knife edge 202A screws into the top surface of terminal pad 107. This prevents compressive or rotational stresses on the relatively fragile contact wires. It will be noted that the foregoing elements define a connect-disconnect means for coupling body 10 to catheter assembly 20, quickly, easily, positively, and sealingly for both mechanical and electrical purposes in one manual operation.

As shown in FIG. 2, stylet funnel 207 and catheter mounting block 205 have apertures therethrough which communicate with the interior of distal coil lead 304. Silicone rubber membranes 206 are adapted to be pierced by a catheter positioning stylet (not shown) inserted through funnel 207 into distal coil lead 304 and to reseal themselves against entry of body fluids into catheter 30 after the stylet is withdrawn. This arrangement permits repositioning of the heart-contacting end of catheter 30 after connection to body 10, without loss of pacing function. Moreover, should the catheter need repositioning after implantation, a stylet can be inserted through a slit in the patient's skin without exposing the whole body or disconnecting the catheter therefrom.

Catheter 30 is constructed to have leads of low electrical resistance and a high degree of resistance to breakage due to flexwire stresses encountered in operation as an implanted assembly. Distal coil 304 comprises three parallel wires wound in a tight helix on a common mandrel. Proximal coil 302 comprises four parallel wires wound in the same manner. Each lead carries a silicone rubber insulating sleeve. These multiwire leads constitute low parallel electrical resistance and provide redundant signal communication paths should one lead happen to break. Both leads employ a high-tensile strength corrosion resistant metal alloy.

The heart contacting end of the catheter is constructed as follows. Proximal electrode 305 is welded with two annular welds 305A to inner shell 306. This assembly is slipped over porximal coil 302 at an exposed end with a short section of coil 302 extending beyond electrode 305. Inner shell 306 is then welded to coil 302 at several annular areas 306A. Rubber sleeve 301 is pulled up to a point just behind electrode 305.

Distal coil 304 and its sleeve 303 are pushed through proximal coil 302; and coil 304 is pulled partially out of sleeve 303 and slipped over shaft 308A on distal electrode 308. Distal tip 309 has previously been welded at annular area 308B to distal electrode 308. Distal coil 304 is welded to shaft 308A at several places, and then sleeve 303 is stretched over electrode 308.

This assembly is then inserted in a mold and partly encapsulated in silicone rubber. This encapsulates and bonds proximal coil 302 to proximal electrode 305 and bonds proximal sleeve 301 and distal electrode 308 and tip 309.

Distal electrode 308 and inner proximal shell 306 are constructed of the same material as coil leads 302 and 304. Proximal electrode 305 and distal tip 309 are constructed of highly corrosion resistant platinum. Any corrosion occurring because of joining of dissimilar metals will thus occur at massive interfaces rather than at the relatively fine wires of the leads. Moreover, surrounding body tissue will be protected from chemical reactions due to any corrosion which occurs by the molded silicone rubber.

The resultant catheter assembly has a very high degree of flexibility and strength. The coaxial coiled wires provide shielding against pickup of RF interference in the distal coil lead. In a unipolar catheter the proximal electrode is eliminated but the proximal lead is retained to provide the RF shielding. This shielding is an important advantage in demand heart stimulators which sense the natural R-wave over the catheter leads.

The above descriptions are given by way of example only and numerous modifications could be made without departing from the scope of this invention as claimed in the following claims.

Claims

I claim:

1. Heart stimulator system adapted to be implanted within a human body, comprising:

a sealed assembly including a sealed enclosure and pulse generating means housed therewithin, said enclosure defining an open cavity;

a catheter having distal and proximal ends and adapted to be coupled to a human heart adjacent said distal end, with at least one electrode for carrying signals between said pulse generating means and said heart, said catheter defining an axially extending interior space;

elongated catheter support means defining a transverse passageway coaxial with said catheter interior space and communicating therewith at one end while being open at the other end, said support means being joined to said catheter adjacent said proximal end;

pierceable self-sealing means for sealing said other open passageway end of said catheter support means;

quick connect-disconnect means for sealingly and simultaneously coupling mechanically and electrically said assembly to said catheter and support transversely to said passageway into a sealed unit, including

a male threaded connector secured to said catheter support means adjacent one end thereof, said connector including a conductive portion therewithin insulated from the remainder of said connector, extending to the leading end thereof, and electrically connected to said one electrode, said catheter and said catheter support means forming an integral elongated lever arm for said threaded connector;

a female threaded connector adapted to receive said male connector therethrough and secured within said cavity at the entrance thereof, said male and female connectors defining an axis upon being united which is transverse to that of said catheter passageway and interior space;

a contact member mounted within said cavity and spaced inwardly from said female connector, said contact member being electrically connected to said pulse generating means,

resilient means positioned in said cavity inwardly from said female connector, and responsive to the passage of said male connector through said female connector for sealing said cavity;

said male connector conductive portion thereupon engaging said contact member, effecting electrical as well as mechanical connection with the sealing of said cavity simultaneously, said connection being tensioned with said lever arm to complete a sealed stimulator system which may be equally quickly disassembled and whose catheter may be stylet-positioned without disturbing said connection.

2. A system as in claim 1 in which said pierceable means for sealing includes a plurality of membranes of pierceable resilient self-sealing material serially mounted one behind the other within said passageway, to permit passage therethrough of a catheter positioning stylet into said catheter interior space, and a subsequent resealing of said passageway upon removal of such stylet.

3. A system as in claim 1 which further includes means for movably, and resiliently mounting said contact member within said cavity whereby said contact member is positively and resiliently biased into contact with said male member conductive portion upon the coupling of said connectors.

4. A heart stimulator system for rapid and simplified high reliability assembly and implantation within the human body, comprising:

a sealed stimulator assembly including a sealed enclosure and electrical pulse generating means housed therewithin, said enclosure defining an open cavity in the surface thereof, said circuitry having a terminal extending into said cavity at an inner portion thereof;

a sealed catheter assembly adapted to be coupled to a human heart and having an elongated catheter and a catheter support portion joining said catheter adjacent one end thereof, said catheter having at least one electrode for carrying signals between said pulse generating means and said heart;

a male threaded connector sealingly secured at one end thereof to said catheter support portion with the connector axis transverse to that of said catheter, said connector defining a central axial aperture therethrough;

a female threaded connector adapted to receive said male connection therethrough and secured within said cavity so as to occupy the cavity entrance, said circuitry terminal being spaced from said female connector;

electrical contact means coaxial with said connectors and operative simultaneously therewith, said means including a conductor member carried within said axial aperture of said male connector and insulated from said male connector, said conductor member being electrically connected adjacent said one connector end to said electrode, said conductor member extending outwardly from the other, leading connector end into a sharp outward projection;

and a contact member movably mounted within said cavity spaced inwardly of and coaxially with said female connector, said contact member being electrically connected to said terminal;

a resilient annular seal positioned in said cavity coaxially with said female connector and inwardly thereof in contact with the wall of said cavity, said seal engaging said conductor upon the passage of said male connector through said female connector;

spring means for urging said contact member toward said female connector, said conductor engaging said seal and compressing it between said end and said wall while said conductor projection engages said contact member upon said connectors being united, whereby said stimulator and catheter assemblies are simultaneously electrically and mechanically connected as well as sealed into a unitary fluid tight system.

5. A heart stimulator system as in claim 4 in which said catheter support portion includes an elongated connector arm extending transversely and substantially across said support parallel to said catheter, and to which said male connector is secured at one connector arm end, said arm extending under said one catheter end, said arm including a clip at the end opposite said male connector, said clip securing said catheter upon said arm, and means potting said connector arm and clip with said one catheter end into an integral assembly to form a lever arm for said male connector adapted to aid in tightening said connectors and ensure high contact forces between said projection and said contact member.

6. A system as in claim 5 in which said catheter support portion includes a terminal member mounted on said arm and insulated therefrom, in a position opposite said male connector so that said arm is therebetween, said terminal being connected electrically to said conductive portion of said male member, as well as to said catheter electrode.

7. A system as in claim 6, in which a passageway is defined through said terminal member and in which said catheter defines an interior axially extending space, said passageway and space being coaxial and extending transversely to the axis of said male connector, and which further includes a plurality of membranes of pierceable resilient, self-sealing material serially mounted within said passageway, thereby sealing said catheter and passageway yet permitting the passage therewithin of a positioning stylet and insuring subsequent resealing upon removal of such stylet.

8. A heart stimulator system as in claim 4 in which said conductor member projection comprises an annular knife edge, and said contact member includes a flat surface facing said annular knife edge, whereby said knife edge digs into said contact surface for optimum contact upon said connectors being united.

9. A heart stimulator system as in claim 4 wherein said contact member includes a lower end section having at least one flat side to limit the rotational excursion of said contact member.

10. A heart stimulator system as in claim 4 wherein said contact member includes a flanged surface facing said sharp projection, and said seal is captured between the periphery of said flange and said cavity wall, said spring member biasing said contact member beneath said flange.