Abstract:
A metallic pulse generator housing has a tubular connector which receives a proximal lead end plug, the connector being located inside the housing and having a closed end within the housing and an open end welded or bonded to an opening in a wall of the housing. The connector is formed by a metallic barrel which is weldable or bondable to the metallic housing, the barrel being a structurally unitary tube member with a cavity containing electrical contacts for contacting contact surfaces on the lead end plug. At least one insulating substrate, on which the contacts are carried, is arranged in or on a region of a barrel wall which defines the cavity.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to a housing and an electrode lead adapter for a heart stimulator. 
     2. Description of the Prior Art 
     An implantable pacemaker (pacer) is a system composed of a pulse generator and the pacing lead(s) connected thereto. At the proximal end of each pacing lead is a male plug (terminal pin) which is connected to the pulse generator, and at the distal end of the lead there is (at least) one electrode adapted to be implanted in (or in the vicinity of) a patient&#39;s heart. The pulse generator normally has a housing (“case” or “can”), which contains a battery and electronic circuitry, and a connector (“header”). The connector is a receptacle into which said pacing lead(s) is (are) inserted. 
     The internal parts of the pacer must be well protected, especially against body fluids, for a long time period. This places strict requirements on all entries into the interior of the housing, especially on the lead connection to the housing. It should also be possible to disconnect the pulse generator from the implanted lead(s), e.g. for replacement or servicing of the generator. The connective parts of the pulse generator and the lead(s) have largely been standardized to include in practice a relatively deep female socket having internal contact surfaces, while the male plug (at the proximal end of each lead) has corresponding external contact surfaces. 
     Conventionally the connective pulse generator housing part containing the female socket is made of a transparent material, usually a medical grade epoxy resin, which is molded onto the housing and onto contacts protruding from the housing. The lead&#39;s male plug is normally locked in the connector receptacle by means of a set-screw or some other fastening means. However, the positioning and alignment of the contact surfaces and of the fastening means or metallic threads for the set-screw, prior to the molding of the connective part, is very complicated, and the delay in the manufacturing process incurred by the curing of the epoxy is considerable. 
     Thus, it would be desirable that such a molding procedure could be dispensed with. 
     It has been considered that a possibility of avoiding these problems might be to design a pulse generator which is provided with a female socket located inside its metal housing, however, such an integrated socket, sometimes called a “black hole”, is presently not used. 
     U.S. Pat. Nos. 4,262,982, 4,934,366 and 5,324,311 describe interior sockets or blind holes in pacemaker housings. In all cases the interior socket has a tubular member formed of a number ofjoined sections of different materials, e.g. metal and insulating ceramics. A metallic end section of the tubular member can be welded or bonded to an opening in the pacemaker housing by means of an exterior flange on the end section. However, the use of sections of different materials in the tubular member makes the assembly procedure more complicated and demanding regarding precision and durability of the components. The integrity of the interior of the housing also must be guaranteed during a very long period of implantation. 
     U.S. Pat. No. 5,007,864 discloses a lead-to-pacemaker adapter which allows the use of a smaller diameter terminal electrode lead assembly than that for which the pacemaker was designed. The adapter permits direct electrical connection from the terminal pin electrode (at the proximal lead end portion) to the pacemaker connector block and its terminal set screw, without any intermediate connecting elements. 
     The adapter is tubular and includes a cylindrical body which tapers at its rear open end to an extension. At its forward closed end the adapter has an end face from which an electrically conductive half-round tube extends outwardly. On its underside the adapter has a retaining bump provided for latching the adapter in place within a receptacle cavity in the pacemaker&#39;s head portion. Near the outer opening of the receptacle cavity there is a small hole along the bottom side thereof. When the adapter is inserted in place within the receptacle cavity said retaining bump engages within said small hole. 
     When the terminal pin electrode at the proximal lead end portion has been inserted into the adapter, the pin electrode will be positioned in the channel-shaped half-round tube at the forward end of the adapter. A socket recess set screw, which is threaded into the connector block, is brought into contact and locking engagement with said pin electrode, thereby retaining the lead assembly in firm mechanical and electrical coupling to the pacemaker. 
     U.S. Pat. No. 4.583.543 discloses an upsizing adapter for electrically and mechanically coupling a small size terminal electrode assembly (which is mounted at the proximal end of a pacing lead) to a large size terminal electrode assembly socket in a pacemaker. The adapter is adapted to be inserted into the electrode assembly socket in the pacemaker, and the electrode assembly at the proximal end of the pacing lead is inserted into a socket in the adapter. Thus, the smaller terminal electrode assembly at the lead&#39;s proximal end is received and held in a larger size socket in the pacemaker by means of the adapter. The adapter with the pacing lead electrode assembly inserted therein is retained in the pacemaker socket by means of an Allen set screw in a connector block within an upper body portion of the pacemaker. A pointed tip of the set screw forces a side wall portion of the adapter&#39;s forward end tube (enclosing the lead&#39;s terminal pin electrode) into contact with the lead&#39;s terminal pin electrode. In this way, an electrical and mechanical connection is provided between the pin electrode and the connector block. 
     SUMMARY OF THE INVENTION 
     A primary object of the invention is to provide a tubular connector for a pulse generator housing that is suitable for so called black holes. 
     A further object is provide a connector which produces a mechanically locking, electrical connection of a proximal lead end portion to the lead connection unit in a pacemaker or some other type of pulse generator. 
     Another object of the invention is to design a tubular connector, as well as an adapter suitable for that type of connector, which facilitates the connection of an undersized proximal lead end electrode assembly to the receiving cavity of the lead connection unit of a heart stimulator. 
     A still further object is to provide a connector including a tubular, male plug receiving member or barrel being designed to be optimized from a manufacturing as well as a strength-of-material standpoint. 
     The above objects are achieved in accordance with the principles of the present invention in a metallic pulse generator housing having a tubular connector adapted to receive a proximal lead end plug, the connector being located inside the housing and having a closed end within the housing and an open end that is welded or bonded to an opening in a wall of the housing. The connector is formed by a metallic barrel which is weldable or bondable to the metallic housing, and has a structurally unitary tube member with a cavity containing electrical contacts for contacting contact surfaces on the lead end plug. At least one insulating substrate is arranged in or on a region of the barrel wall which defines the cavity. The substrate has contacts on a surface thereof facing into said cavity. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a partly assembled tubular connector according to the invention. 
     FIG. 2 shows (on a larger scale) a bottom view of the connector in FIG.  1 . 
     FIG. 3 shows an end view of the connector in FIG.  2 . 
     FIG. 4 shows a longitudinal section through the connector, at plane IV—IV in FIG.  3 . 
     FIG. 5 shows an end view of the inventive connector in fully assembled state. 
     FIG. 6 shows a longitudinal section through the connector in FIG.  5 . at plane VI—VI thereof. 
     FIG. 7 shows an end view of the barrel of the tubular connector in FIGS. 1-6. 
     FIG. 8 shows a longitudinal section through the barrel in FIG. 7, at plane VIII—VIII thereof. 
     FIG. 9 shows a bottom view of the adapter of the tubular connector in FIGS. 1-6. 
     FIG. 10 shows a side view of the adapter in FIG.  9 . 
     FIG.  11  and FIG. 12 show end views of the right and left ends, respectively, of the adapter in FIG.  9 . 
     FIG. 13 shows a longitudinal section through the adapter in FIG. 11, at plane XIII—XIII thereof. 
     FIG. 14 shows (on a larger scale) a side view of the substrate slab of the connector in FIG.  4 . 
     FIG. 15 shows a cutaway side view of a pulse generator with a tubular connector barrel mounted in the upper part of the pulse generator housing. 
     FIG. 16 shows a partially cutaway side view of a pulse generator with a tubular connector barrel included in a specific receptacle part (header) of the generator. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of a metallic housing with tubular connector according to the invention will now be described with reference to FIGS. 1-6 and the three major components thereof are depicted separately in FIGS. 7-8,  9 - 13  and  14 , respectively. 
     In FIGS. 1,  2 ,  4  and  6  a tubular connector  2  is shown in a partly assembled state. The connector, which is adapted to form part of a lead connection unit  100  of a heart stimulator or pulse generator schematically shown in FIG. 15, has a metallic barrel  4  with a cavity  6  having an entrance opening  8  at its rear end (right end in FIGS.  4  and  8 ). In a thickened side wall portion  10  of the barrel  4  there is formed an elongated, longitudinal through opening  12  between the cavity  6  and the outside of the barrel. A rectangular slab or substrate  14  of ceramic material is sealingly fastened in opening  12 , e.g. by brazing solder  16 . On its narrow longitudinal top side  18  the slab  14  is provided with two spaced apart contacts  20 ,  22  with convex surfaces that are metallized with e.g. gold. These contacts are individually electrically connected to a pair of external pads  24 ,  26  on a lateral surface  28  of the slab, see FIGS. 1 and 14. 
     The substrate  14  may, however, alternatively be an integral part of the substrate carrying the internal electronics of the pacer, this substrate thus extending into the opening  12  and being sealingly fastened thereto. In the case of a pacer with two connectors, the connectors could be located on opposite sides of the electronics substrate with the substrate extending into the respective openings  12 . In both cases, separate conducting means connecting the internal electronics with the barrel would not be necessary. This design of course could be used regardless of whether the embodiment utilizing the adaptor part is used or an embodiment is used in which the means connecting the substrate with the male connector are permanently mounted in the barrel. 
     As shown in FIGS.  1 , 2  and  4  a tubular adapter  30  is insertable and sealingly lockable in the barrel cavity  6 . This adapter, which constitutes a casing with a central bore  32 , is made of an elastic, electrically insulating material, e.g. a semi-soft elastomer, which may be transparent to allow easy visual supervision of the position of a proximal lead end portion  34  which is inserted into the adapter bore  32 . The rear end portion of the adapter is axially split open into two half-shells  36 ,  38 . Each half-shell has an outward flange  40  at its rear end. As visible in FIGS. 1-3 and  9 - 13  one half-shell  38  is elastically and flexibly connected with the rest of the adapter by a transition portion  42 . 
     The half-shells  36 ,  38  are provided, on the insides thereof, with a locking mechanism adapted to lock the proximal lead end portion  34  in its fully inserted position in adapter bore  32  when also the adapter itself has been fully inserted into the barrel cavity  6 . This locking mechanism includes circumferential engagement elements, e.g. ribs  44 , which are brought into engagement with the lead end portion  34  when the half-shell  38  is turned down (from its angular position shown in FIGS. 1-3) to its axial engagement position obtained by fully inserting the adapter  30  into barrel cavity  6 , as shown in FIG.  6 . 
     Furthermore, to space apart and mutually seal the electrical pole surfaces  46 ,  48  on the outside of the adapter tube or casing from each other in barrel cavity  6 , the adapter is provided, on the outside thereof, with axially spaced apart circumferential grooves  50 ,  52 ,  54  (see FIGS. 9,  10 ,  13 ) adapted to accommodate  0 -ring type sealing elements  50   a ,  52   a ,  54   a  (see FIGS.  4  and  6 ). 
     When the adapter  30 , with the lead end portion  34  fully inserted therein (as in FIG.  4 ), has been axially fully inserted in barrel cavity  6  (as in FIG.  6 ), the adapter is positively locked in position therein by being turned clockwise 90°, so that slots  56 ,  58  (which contain the pole surfaces  46 ,  48 ) will slide onto the convex contacts  20 ,  22  on slab  14 . Thereby the adapter will become mechanically locked in position in cavity  6 , and the metal parts (e.g. thin metal leafs carrying pole surfaces  46 ,  48 ) molded in the elastomeric adapter will become electrically connected to the convex or spherical, metallic contacts  20 ,  22  on the ceramic material slab  14 . 
     To facilitate the 90° turning of the adapter, the flanges  40  of the two half-shells  36 ,  38  are provided, at the edges thereof, with a suitable number of notches  60  adapted to be engageable by means of an external, simple, adapter turning tool (not shown on the drawings). To turn the adapter this tool is merely folded around the lead end portion  34  and fit into the notches  60  in the adapter flanges  40 , whereupon the adapter can be turned 90° to its definite locking position. 
     The tubular connector  2  is adapted to form part of a lead connection unit of a heart stimulator or pacemaker. Such a unit can be positioned in a header or specific receptacle part of a pacemaker, or in a “black hole” cavity provided in the actual pacemaker housing or can. To facilitate the installation of the tubular connector according to the invention in a header or such black hole, the barrel  4  preferably is provided with a circumferential flange  62  in the region of its entrance opening  8 . By means of this flange the adapter can be attached easily to the pacemaker can, e.g. by laser welding. 
     In FIG. 15 there is shown a pacemaker housing or can  64  containing a connector barrel  4 , electrical circuits  66  and a battery  68 . In this case the barrel  4  is mounted in an opening  70  in a side wall portion  72  of the upper part of the housing  64 . The barrel  4  is attached to the wall portion  72  by means of the circumferential flange  62  which is laser welded to the wall portion. The preferably cylindrical cavity  6  within the barrel  4  is adapted to receive and support an adapter  30  (having a proximal lead end portion inserted therein), in the way shown in FIG.  6 . Thus, the socket configuration shown in FIG. 15 is of the “black hole” type. A substrate  14 , which is made of an electrically insulating material and provided with contacts  20 .  22 , is sealingly fastened in a longitudinal through opening in a thickened wall portion  10  of the barrel  4 . 
     In FIG. 16 there is shown a more conventional pacemaker having a housing or case  74  with a specific receptacle part or header  76  attached thereto. This header  76  may e.g. be an epoxy resin body  78  molded on a planar top surface  80  of case  74 . The tubular connector barrel  4  may be embedded in epoxy body  78  from the very molding thereof or may be inserted afterwards in a cylindrical cavity formed in the molded body. 
     In the preferred embodiment described above, the cavity having the insulating substrate has been illustrated as being located laterally in the envelope surface of the tubular connector (which in the preferred embodiment is cylindrical). It should be noted that the insulating substrate of course could be located in the end of the connector for instance forming a plug brazed or soldered into the end of the connector. The inner side of the plug then could carry the spaced-apart contact surfaces, which for instance could be arranged concentrically on said inner surface and which would be in electrical connection with the exterior of the tubular connector. The tubular adapter would be provided with corresponding exterior contacts on the outer end surface being in electrical connection with the contacts on the inside of the adapter. In other respects the design would be similar to the design described in the preferred embodiments with lateral slots and lugs forming a bayonet joint between the adapter and the connector. 
     Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art.