CONNECTING PARTS FOR MULTIPOLAR PIN CONNECTION OF AN ELECTRODE CABLE FOR AN IMPLANTABLE MEDICAL DEVICE

Abstract: The invention relates to an implantable medical device, preferably a heart stimulator (2), comprising a hermetically sealed enclosure (4, 4'), containing electrical circuits (6) and a source of power (8), and a connecting part (10) affixed to the enclosure or incorporated therein for electrical connection of the proximal end of an electrode cable (12) to circuits in the enclosure. According to the invention, a first connector (16, 16'), devised as a female connector part with contact means (26, 26') embedded in a puncturable membrane (24, 24'), is arranged in said connecting part, said first connector (16, 16') being designed to be placed in electrical contact with a second connector (18, 18'), which is arranged as a male connector part on the proximal end of the electrode cable (12) and which is equipped with two or more contact needles (32a, 32a', 32b, 32b'...) pointing in the same direction with tips and being insertable into the membrane (24, 24') which are brought into contact with the associated contact means (26, 26') in the membrane (24, 24') of the first connector (16, 16') when the connectors (16, 16'; 18, 18') are coupled.

Description: Connecting parts for multipolar pin connection of an electrode cable for an implantable medical device Field of the invention The present invention relates to connecting parts for an implantable medical device, preferably a heart stimulator, in accordance with the preamble of the appended independent claims. The prior art US A 4 934 366 describes an implantable medical device in the form of a heart stimulator (pacemaker) in a hermetically sealed enclosure containing electrical circuits, a battery connected to the circuits and a connector part through which the proximal end of an electrode cable can be connected to the heart stimulator and electrically coupled to its circuits. The connector part comprises a tubular sleeve devised as a female connector part with a stepped, cylindrical receptacle, closed at its inner end and open on the end opening onto the exterior of the enclosure, and a middle section between both these channel sections. The diameter of the channel is smallest in its innermost section, largest in its outermost section and intermediate in size in its middle section. A first, ring-shaped coil spring contact means is in the wall of the inner part of the receptacle channel, and a second ring- shaped coil spring contact means is in the wall of the middle section. Both these contact means are electrically connected to the pacemaker's electrical circuits. A connector, devised as a male connector with an anterior, narrow, pin-like tip electrode and a ring-electrode, arranged somewhat behind same and with a larger diameter than the diameter of the tip electrode, is devised to interact with the device's tubular female connector. When the male connector is inserted into the female connector, the tip electrode and the ring electrode are brought into electrical contact with the respective coil spring contact means in the tubular connector. The tip electrode, devised as a cylindrical male connector, is axially separated from the ring electrode by a cylindrical spacer made of an electrically non-conductive material. The receptacle of the tubular connector, devised as a female connector, is also equipped with circular ring seals in the inside walls of the receptacle. These seals are intended to keep the two electrode of the male connector from coming into electrical contact with each other via body fluid which could seep in through the gap between the exterior of the male connector and the interior of the female connector. The exterior of the male connector behind the ring electrode, which has the greatest diameter, also has encircling, external sealing ribs to seal against the interior of the female connector, thereby preventing the entry of fluid into the aforementioned gap. Devising the electrically non-conductive spacer section between the tip electrode and a ring electrode at the proximal end of an electrode cable with external, encircling sealing ribs with intermediate grooves is also previously known. The device according to US A 4 934 366 relates to bipolar connection of an electrode cable to the device's connector part. Since the contact means/electrodes of the interconnectable male and female connector parts therein are axially separated by intermediate spacer sections, a connector is achieved with a relatively great axial length. This length is obviously a disadvantage, since the aim is always to achieve the smallest possible external dimensions for an implantable device of the present kind. As regards heart stimulators, the trend is towards heart stimulation with the aid of more than two electrodes, implantable in the heart, on the electrode cable. However, refinement of the aforementioned known type of axial, bipolar electrode connection to instead comprise e.g. three or more electrodes results in an even longer connector part, since more than two coaxial electrodes must then be arranged in axially separate locations with intermediate spacers. The need for effective sealing means (e.g. sealing ribs) to separate the electrodes (i.e. the poles) from each other in the connector at the proximal end of the electrode cable increases to a corresponding degree. So, multipolar electrode connection increases both the size and constructional complexity of the sealing means employed to separate the poles from one another. Summary of the invention One first object of the present invention is therefore to achieve connecting parts for an implantable medical device suitable for multipolar electrode connection. The connecting part of the implantable device is then devised as either a part permanently affixed (e.g. molded-on) to the device's enclosure or built-into or affixable to the device's enclosure. A second main object of the invention is to achieve connecting parts for a medical device, suitable for multipolar electrode cable connection, in which the axial length of the connecting parts is independent of the number of connecting electrodes (poles) in the contact on the electrode cable's proximal end. A third main object of the invention is to achieve connecting parts for an implantable medical device in which the connecting parts can have a single, shared sealing means to separate and insulate the male connector part's poles from each other. The problems associated with the aforesaid objects are solved according to the invention in that the connecting parts for an implantable medical device of the initially stated kind has the features set forth in the characterizing part of the independent claims . Preferred embodiments of the device according to the invention can also display the features set forth in the dependent patent claims. A primary feature of the device according to the invention is therefore that a first connector, devised as a female connector part with contact means, embedded in a puncturable membrane, is arranged in the enclosure, the first connector devised to be brought into electrical contact with a second, connector part, devised as a male connector part, on the proximal end of the electrode cable. This second connector is equipped with at least one contact needle, with a tip insertable into the membrane, which is brought into contact with the associated contact means in the membrane of the first connector when the connectors are coupled. Each contact needle can be appropriately enclosed in insulation except in the area of the outermost part of the needle tip. The membrane is self-sealing, i.e. the membrane will resiliently and sealingly enclose the tips of the contact needles when the needles are inserted in the membrane . The opening made by the needle will also close if the needle is withdrawn. The first connector, devised as a female connector part, may appropriately be permanently mounted at the bottom hole end of an oblong receptacle provided in the connector, the second connector and the walls of the receptacle being provided with interacting position-fixation means preventing undesirable rotation of the second connector in the receptacle and ensuring the desired axial orientation and interaction of associated connector means- connector needles. The male connector part may be a DIN-type connector part. In this embodiment the connector part is designed as a part permanently affixed (e.g. molded-on) to the device's enclosure or built-into the device's enclosure. In another embodiment the female connecting part may be provided directly in a surface contact part of the enclosure and the male part may be designed as a connector part having a contact surface which is contoured to conform with the enclosure contact surface, separate attaching means, for instance in the form of an attachment screw, being provided for attaching the connector part to the enclosure in conjunction with position-fixation means. The contact means in the first connector's membrane are preferably metallic contact plates, elastically arranged (suspended and/or supported) in the connector and electrically connected to circuits in the enclosure by separate conductors in the connector part. In one embodiment of the device, the metallic contact plates are embedded in the membrane made of an electrically insulating elastic material, such as rubber or plastic. Alternately, the metallic contact plates could be movingly arranged inside open recesses in the membrane, on the side facing the connecting part, pressure springs, which pre-tension the contact plates, being mounted in the recesses between the plates and the said bottom. The membrane is preferably made of an electrically insulating, elastic material, such as rubber or plastic. The second connector preferably comprises a basic body of electrically insulating material holding the connector's contact pins, and this basic body has an end surface from which the projecting parts, formed by the contact needles, of the contact pins, are parallel to each other, i.e. side by side. Description of the drawings The invention will now be further described and explained with the embodiments, schematically depicted in the attached drawings, showing how the connecting part of an implantable heart stimulator (pacemaker) and the connecting part on the proximal end of its associated electrode cable can be devised in achieving the invention. The FIGURES in the drawings are only intended to elucidate the principle of the construction of the invention and do not claim to show the invention with dimensional accuracy or to scale. The following applies to the FIGURES shown in the drawing: FIG. 1 shows, in a lateral, partially sectioned view, a first embodiment of the connector area of a heart stimulator with relevant parts of a connected connector on the proximal end of an associated electrode cable (not shown) ; FIG. 2 is a perspective view, on a larger scale, of a partially sectioned connector on the proximal end of the electrode cable; FIG. 3 shows, on an even larger scale, the end area of a connector's contact pins inside the circle S in FIG. 2. FIG. 4 shows a section through the membrane at the bottom hole end of the heart stimulator's connector receptacle according to FIG. 1. FIG. 5 show a section, corresponding to the section in FIG. 4, through a membrane at the bottom hole end of the connector receptacle. FIG. 6 illustrates schematically another embodiment of the invention in which the connector on the proximal end of the electrode cable is designed as a connector part to be attached against the housing. Preferred embodiments of the invention Referring first to FIG. 1 which, in a lateral, partially sectioned view shows the upper part of a heart stimulator or pacemaker generally designated 2. In the customary manner, the heart stimulator comprises a hermetically sealed enclosure 4 containing electrical circuits 6 and a power source 8, e.g. in the form of a battery. Near or in the upper part of the enclosure 4, a connecting part 10 is arranged for electrical connection of the proximal end of an electrode cable 12 (cf FIG. 2) to the circuits 6 in the enclosure 4. The connecting part 10 has an oblong receptacle 14, intended for receiving a first connector 16 into the connector part and a second connector 18 on the electrode cable's proximal end 12 (cf FIG. 2) which can be inserted into the receptacle 14 for coupling with the connector 16. The preferably cylindrical receptacle 14 has an input end 20, opening onto the exterior of the connecting part, and a bottom hole end 22 inside the connecting part 10. The first connector 16, devised as a female connector part, is therefore arranged at the bottom hole end 22 of the receptacle 14. The connector 16 comprises a puncturable membrane 24 made of an elastic, electrically insulating material, such as rubber or plastic. Two or more contact means 26, depending on whether the connector 16 is bipolar or multipolar, are enclosed in this membrane 24. The number of contact means 26 in the connector 16 obviously depends on whether the connector on the distal end (not shown) of the electrode cable 12 has two or more active electrodes, i.e. whether it is bipolar or multipolar. For the sake of simplicity, the connector 16 in FIG. 1 is shown as a bipolar connector, i.e. a connector with only two separate contact means 26. The connector 16 shown in FIG. 1 could also be devised as a quadripolar connector, only two of the contact means 26 being shown in FIG. 1. The contact means 26 in the connector's 16 membrane 24 are metallic contact plates which are elastically arranged in the membrane 24 in the connector part 10 and which are electrically connected to the circuits 6 in the enclosure 4 by separate electrical conductors 28 and 30 respectively in the connector part. The first connector 16, arranged as a female connector part in the connecting part 10, is therefore designed for electrical coupling to the second connector 18, devised as a male connector part, on the proximal end of the electrode cable 12 when inserted into the receptacle 14 and for coupling to the connector 16. The second connector 18 (cf FIG. 2) is a DIN-type connector, i.e. it consists of a sleeve-like, hollow, cylindrical connector with two or more parallel contact needles or contact pins 32a, 32b, ... If the connector 18 is e.g. a multipolar connector with four, five or more contact pins 32, the pins are appropriately arrayed in a ring around the cylindrical connector's 18 imaginary central axis in the known manner. As the enlargement in FIG. 3 shows, contact needles or pins 32 can be inserted without difficulty into the elastic membrane 24. As FIGS. 3 and 4 show, each contact needle 32 is provided with surrounding insulation 34, except in the area of the outermost part 36 of the neeule tip which is intended to be brought into electrical contact with an associated contact means 26 in the membrane 24. The main purpose of the insulation 34 is to keep the metallic contact needle from coming into contact with the body fluid which could invade the receptacle 14 after the heart stimulator 2 has been implanted into the body. As an alternative to providing the contact needles or pins 32 with such insulation, the interior of the receptacle 14 could be equipped, at appropriate sites and/or on the exterior of the connector 18, with appropriate sealing means which keep body fluid from invading the space between the connector's free, anterior end surface and the connector's 16 opposing frontal surface, i.e. the membrane's 24 frontal surface. Thus, the membrane 24 serves as a common sealing means for all the contact pins, thereby achieving both sealing and insulation between the non-insulated end sections 36 of the needles. The length of the contact needles 32 could e.g. be about 5 mm, and the length of the non-insulated end section 36 must obviously be less than the membrane's 24 thickness, which e.g. could be about 3 mm. The length of the end section 36 can be very small, e.g. 0.1 mm. The contact means 26 devised as metallic contact plates can be completely embedded in the membrane 24, whereby membrane material in the area 38 between the contact means 26 and the receptacle's 14 bottom 40 serves as an elastic shim when each contact means 26 establishes contact with the sharp-tipped end section 36 of the respective contact needle, thereby being pressed towards the bottom 40. However, the elastic inclusion of contact means 26 in the membrane 24 can be achieved in many different ways, one being shown in FIG. 5. In this instance, contact means 26 devised as metallic contact plates are movingly arranged inside open recesses or holes 42 in the membrane 24, on the side facing the bottom 40 of the receptacle 14. In this instance, pressure springs 44, exerting a pre-tensioned force on the contact plates 26 towards the non-insulated end sections or tips 36 of the contact needles, are arranged between the plates 26 and the bottom 40. The second connector 18 comprises a basic body 46, made of an electrically insulating material, which holds a connector's contact pin 32. The sharp-tipped contact means 32, projecting from the free end surface 48 of this basic body, are parallel to each other. As the above shows, the first connector 16 is permanently arranged at the bottom hole end of the receptacle 14 , and appropriately interacting position-fixing means, intended to prevent undesirable rotation of the second connector 18 in the receptacle 14, are provided on the second connector 18 at the proximal end of the electrode cable 12 and in the wall of the receptacle. The task of these position-fixation means is to achieve the desired positioning of the connector 18 when the latter is inserted into the receptacle 14, thereby ensuring the desired axial positioning and interaction of associated contact means 26 and contact needles 32. These position-fixation means can e.g. consist of a axial slot 50 in the wall of the connector 18 and a bump 52, mating with this slot, on the interior wall of the receptacle 14. It should be noted that the second connector 18 does not necessarily have to be cylindrical but may have any suitable cross-section, for instance a cross-section which is square or rectangular. In this case the cross-sectional shape of the connector could serve as said position-rotation means in conjunction with an oblong receptacle having a complementary shape. This DIN-type connector also has the advantages of a standard DIN-connector as used in audio applications in which for instance the female part would contain a set of contacts connected to both input and output means whereas the male part might only contain a smaller number of pin contacts for connection to the input means whilst still fitting the female contact. The male part in the DIN-type connection described above thus could contain fewer needle contacts contacting only a selection of the contacts in the female part which would correspond to a selection amongst the possible functions of the pacer. Fig 6 illustrates a variation of the above embodiment. In this embodiment a male connector part 18' is designed to be attached to the outside of the enclosure. The male connector part 18' preferably has the general configuration of a standard molded-on connector part with standard 3.2 mm female connection openings 60, 61 for standard lead connections such as any of the IS-1 or VS-1 standards. The connector part 18' may of course be provided with any kind of detachable lead connection, including the DIN- type connection described above. The leads may also be permanently attached to the connector part. The contact surface 62 of the connector part 18' is contoured to conform with one part of the surface of the enclosure serving as the enclosure contact surface 63. This side of the connector part is provided with one or more contact needles 32a', 32b' extending from the surface and pointing in the same direction. The design of the needles may be any one of the designs described above in connection with the DIN-type connector. The enclosure contact surface 63 is provided with contact means 26' embedded in a puncturable membrane 24' arranged flush with the surface or slightly recessed therein. The design of these contact means 26' and membranes 24' may be any one of the designs described above in connection with the DIN-type connector. The connector part 18' may be provided with position-fixation means . These means may for instance be in the form of a peripheral groove on the male connector part cooperating with a corresponding flange on the enclosure or vice versa. The groove further could contain a sealing means in the form of a flexible sealing bead pressed into the groove. Of course any cooperating means which prevents rotation by means of mutual, complementary shapes could be used. The position-fixation means cooperate with attachment means which may be in the form of one or more screws 64 which can be screwed into a threaded bore in the enclosure. As in the case of the DIN-type connector described above, the number of the contact means may be adapted to the number of different functions the pacemaker may have, the number and location of the contact needles either being adapted to the locations of all contact means or being adapted to the number and locations of contact means corresponding to a selection of the functions it is desired to utilize in a particular case. As indicated above, normally a contact block made of transparent epoxi resin is molded against the enclosure, the female contact means for the proximal end of the lead being molded into the contact block at the same time that the block is molded against the enclosure. This procedure is complicated and time-consuming, one reason being that the curing of the epoxi resin after the molding of the block onto the enclosure takes time. This second embodiment with a connecting part in the shape of a molded-on part thus has the advantage that the connecting part and the enclosure can be manufactured separately and independently under the most favorable conditions for the respective component. Given that the enclosure has several female contacts corresponding to a number of different functions, it will be easy to manufacture pacers with different functions without essentially altering the enclosure and its contents since the locations and numbers of the male contacts in the block freely can be chosen to give a specific selection of functions. The block can be attached to the enclosure either at the manufacture or possibly in connection with the implantation of the device.

Claims: Claims 1. A female connecting part for an implantable medical device, preferably a heart stimulator (2) , said medical device comprising a hermetically sealed enclosure (4, 4'), containing electrical circuits (6) and a source of power (8) , said female connecting part (10) being affixed to the enclosure or incorporated therein for electrical connection of the proximal end of an electrode cable (12) to circuits in the enclosure, characterized in that a first connector (16, 16'), devised as a female connector with contact means (26, 26') embedded in or located behind a puncturable and self-sealing membrane (24, 24 ' ), is arranged in said connecting part, said first connector (16, 16') being adapted to be placed in electrical contact with a second connector (18, 18'), which is arranged as a male connector on the proximal end of the electrode cable (12) and which is equipped with at least one contact needle (32a, 32a', 32b, 32b' ...) being insertable into said membrane (24, 24') said needle (s) being brought into contact with the associated contact means (26, 26') in the membrane (24, 24') of the first connector (16, 16') when the connectors (16, 16 ' ; 18, 18') are coupled. 2. The connecting part according to claim 1 characterized in that said connecting part (10) contains an oblong receptacle (14) opening onto the exterior of the connecting part and with an entry end (20) and a bottom hole end (22) inside the connecting part for admitting a connector, said first connector (16) being arranged at the bottom hole end of the connecting part, said first connector (16), being devised as a female connector part, with contact means (26) embedded in a puncturable membrane, said first connector (16) being adapted to be placed in electrical contact with said second connector (18) which is arranged as a male DIN-type connector part on the proximal end of the electrode cable (12) equipped with at least one contact needle. 3. The connecting part according to claim 1, characterized in that said first connector (18') comprises a contact surface (63) on the enclosure (4') in which said contact means (26') are arranged, said first connector being adapted to cooperate with said second connector part (18') which has a contact surface (62) contoured to conform with the contact surface (63) , said contact needles (32a', 32b'...) being arranged on and extending from said contact surface (62) . 4. The connecting part according to any one of the preceding claims, characterized in that the contact means (26, 26') in the first connector's (16, 16') membrane (24, 24') are metal contact plates which are elastically arranged in the connecting part (10) and electrically connected to the circuits (6) in the enclosure (4) by separate conductors (28, 30) in the connecting part. 5. The connecting part according to claim 5, characterized in that the metallic contact plates (26, 26') are embedded in the membrane (24, 24') which is made of an electrically insulating, elastic material, such as rubber or plastic. 6. The connecting part according to claim 5, characterized in that the metallic contact plates (26, 26') are movingly arranged inside open recesses (42) in the membrane (24, 24') on the side facing the connecting part, and pressure springs (44) to pre¬ tension the plates (26, 26') are mounted in the recesses between the plates and the said bottom (40) . 7. The connector part according to any one of the preceding claims, characterized in that the membrane (24, 24') is made of an elastic electrically insulating material, such as rubber or plastic. 8. The connecting part according to any of claims 1, 2, 4 - 7, characterized in that the first connector (16) is permanently arranged in the bottom hole end of the receptacle (14) , the walls of the receptacle having position-fixation means (52) intended to interact with position-fixation means (50) on said second connector (18) in order to prevent rotation of the second connector (18) in the receptacle (14) and ensure the desired axial positioning of and interaction between associated contact means-contact needles (26, 32) . 9. The connecting part according to any one of claims 1, 3 - 7, characterized in that the first connector (16') has position- fixation means intended to interact with position-fixation means on said second connector (18') in order to prevent rotation of the second connector (18') in its coupled state and ensure the desired axial positioning of and interaction between associated contact means-contact needles (26', 32') . 10. A male connecting part for an implantable medical device, preferably a heart stimulator (2) , said medical device comprising a hermetically sealed enclosure (4, 4') , containing electrical circuits (6) and a source of power (8) , for electrical connection of the proximal end of an electrode cable (12) to circuits in the enclosure, characterized in that a second connector (18, 18') is arranged as a male connector part on the proximal end of said electrode cable (12) , said connector part being equipped with at least one contact needle (32a, 32a', 32b, 32b' ...), each contact needle (32, 32') being provided with encircling insulation (34), except in the area of the needle tip's outermost end part (36), said second connector (18, 18') being adapted to cooperate with and to be brought into electrical contact with a first connector (16, 16 ' ), which is devised as a female connector part with contact means (26, 26 ' ) embedded in or located behind a puncturable and self-sealing membrane (24, 24') , said needles being insertable into said membrane (24, 24') in order to be brought into contact with the associated contact means (26, 26') in the membrane (24, 24 ' ) of the first connector (16, 16') when the connectors (16, 16'; 18, 18') are coupled. 11. The connecting part according to claim 10 characterized in that said second connector (18) is arranged as a male DIN-type connector part on the proximal end of the electrode cable (L2), said DIN-type connector being equipped with at least one of said contact needles (32a, 32b... ) . 12. The connecting part according to claim 10, characterized in that said second connector part (18') has a contact surface (62), said contact needles (32a', 32b'...) being arranged on and extending from said contact surface (62) , said contact surface (62) being contoured to conform with contact surface (63) on the enclosure (4') in which said contact means (26') are arranged and with which it is adapted to cooperate. 13. The connecting part according to any of the claims 10 - 12, characterized in that the second connector (18, 18') comprises a basic body (46) , made of an electrically insulating material, holding the connector's contact pin (32, 32 ' ), said basic body having an end surface (48) from which parallel contact needles, forming the projecting parts of the contact pin (32, 32') , extend. 14. The connecting part according to any of claims 10, 11, 13, characterized in that and said second connector (18) has position-fixation means (50) adapted to interact with position- fixation means (52) on the wall of said receptacle which prevent rotation of the second connector (18) in the receptacle (14) and ensure the desired axial positioning of and interaction between associated contact means-contact needles (26, 32) . 15. The connector part according to any one of claims 1, 3 - 9, characterized in that the second connector (18') has position- fixation means adapted to interact with position-fixation means on said first connector (16') in order to prevent rotation of the second connector (18') in its coupled state and ensure the desired axial positioning of and interaction between associated contact means-contact needles (26', 32') .

Inventors: LINDEGREN ULF, LINDEGREN, ULF
Applicants: LINDEGREN ULF, PACESETTER AB, LINDEGREN, ULF
Application year: 1997
Main classification: A61N1
IPC codes: A61N1