Abstract:
An implantable heart stimulator has a connector for an electrode lead in the form of a self-contained tubular connector, which can be placed as a unit in one-half shell of a stimulator housing, together with a hybrid circuit and a power source. The other half shell of the stimulator housing can then simply be placed over these assembled components and joined thereto by welding, thereby considerably simplifying manufacture and assembly of the stimulator. When an even number of such self-contained connector tubes is employed, the two stimulator housing half shells can be identical.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to a housing for an implantable stimulator, such as an implantable pacemaker, with at least one electrode connector for electrically and mechanically connecting the internal components of the stimulator to an electrode lead. 
     2. Description of the Prior Art 
     Implantable stimulators, such as a pacemaker, have a housing (also known as a “can”) which contains electronic circuitry and a power source (battery). The stimulator delivers stimulation energy, usually in the form of pulses, in vivo to tissue, such as cardiac tissue, via electrodes which are implanted so as to be in contact with the tissue. One or more electrode leads connect the stimulator to these electrodes. The leads must be mechanically and electrically connected to the housing. A single lead having multiple conductors, leading to respectively different electrodes, can be employed, or multiple leads can be used. 
     The internal components contained in the housing must be protected against the surrounding environment, especially body fluids, over a relatively long period of time. This requirement imposes high demands on all possible entry paths into the interior of the housing, and particularly on the connections of the leads to the housing. A fluid-type connection must be made between the lead or leads and the housing, but the connection must also afford the possibility to disconnect the stimulator housing from the implanted leads for replacement or servicing of the stimulator. 
     The connective parts of the stimulator and the leads have been substantially standardized in the pacing field, and generally a relatively deep female socket is used at the stimulator housing, which has a number of contact surfaces, and the lead or leads have a male portion carrying one or more corresponding, peripherally disposed, generally circular, contact surfaces. 
     Conventionally, the socket portion of the connection is made of a transparent material, usually epoxy resin, which is molded onto the stimulator housing, encompassing contacts which extend outwardly from the housing. The male portion of the lead is normally locked in this socket by set screws, although many other fastening arrangements are known in the art. The positioning and alignment of the different contact surfaces, and the positioning and alignment of the metallic threads for the set screws, prior to the molding of the female portion of the connector is relatively complicated, and there is also an unavoidable delay in the manufacturing process which arises due to the time needed for the epoxy resin to cure. 
     Moreover, since the connector is disposed at the top of the stimulator housing, the two halves of the housing which are joined together, after the circuit, power source and other components have been mounted therein, must necessarily be non-identical, and are usually mirror-symmetric. This requires that two differently shaped housing halves be manufactured and maintained in inventory. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a connector for an implantable stimulator device which can be assembled in the stimulator housing without the necessity of a molding procedure, which still providing the necessary fluid-tight mechanical and electrical connection of the electrode lead to the components contained in the stimulator housing. 
     The above object is achieved in accordance with the principles of the present invention in a connector for an electrode lead which is completely self-contained in an exterior tube, and which can be assembled, as a tubular unit, using two identical housing halves. 
     The entire assembly is prefabricated with an exterior tube, and it is then only necessary to weld the tube into or onto one of the housing halves. When two such prefabricated tubes are employed, the housing halves can be identical, and there is no need to separately manufacture, and maintain in inventory, two different, mirror-symmetrical, housing halves, as is necessary with conventional molded connections. 
     The electrical connection between the prefabricated tube and the hybrid substrate in the stimulator housing can be made directly, without the need for feed-throughs, by allowing the edge of the substrate to extend into a slot in the exterior tube, with the substrate being bonded thereto by welding, brazing or gluing. The substrate edge can be provided with contacts which may directly contact the contact pin of the lead, or can produce an electrical contact with the lead via an adapter. The two prefabricated tubes can then be attached to the substrate in advance so as to form a unit, and the entire unit then being placed in one housing half of the stimulator and connected to the battery, after which the other housing half is welded onto the first half. This is a considerable simplification over conventional procedures, wherein thin wires must be bonded to the feed-through block and to the substrate after mounting of the parts. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration of the internal components of an embodiment of a tube connector for use in the inventive stimulator. 
     FIG. 2 is a side view of a weld protector for the internal components shown in FIG.  1 . 
     FIG. 3 shows a titanium sleeve at the left part of the figure, which is slid onto the components in FIG. 1 covered by the weld protector of FIG. 2, to result in the assembly shown at the right part of the figure. 
     FIG. 4 shows the completed tubular connector in accordance with the invention. 
     FIG. 5 is a side sectional view of a more detailed embodiment of the tubular connector in accordance with the invention. 
     FIG. 6 shows a stimulator in accordance with the invention with two tubular connectors, in assembled form. 
     FIG. 7 shows the stimulator of FIG. 6 with the upper half of the stimulator removed. 
     FIG. 8 shows another embodiment of a stimulator in accordance with the invention employing tubular connectors, in assembled form. 
     FIG. 9 shows the stimulator of FIG. 8 with the top housing half removed. 
     FIG. 10 shows a stimulator employing a tubular connector in accordance with the invention in a further embodiment using a conventionally-shaped housing, with the top housing half removed. 
     FIG. 11 shows the stimulator of FIG. 10 in completely assembled form. 
     FIG. 12 is a sectional view of a further embodiment of a tubular connector in accordance with the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The internal components of a tubular connector in accordance with the invention are schematically shown in highly simplified form in FIG.  1 . These components include an interior tube  1  and a feed-through block  2 , with conductors  3  and  4  proceeding through the feed-through block  2  and being electrically and mechanically connected to the interior tube one. FIG. 2 shows a weld protection sleeve  5 , having a longitudinal slot  6  therein, in which the components shown in FIG. 1 are contained so as to be protected against subsequent welding. FIG. 3, at the left, shows a titanium sleeve, also having a longitudinal slot  8  therein, which is slid over and welded to the sleeve  5  shown in FIG. 2, resulting in the assembly shown at the right of FIG.  3 . The slots  6  and  8  coincide in the assembly shown at the right of FIG.  3 . 
     In the finished tubular connector shown in FIG. 4, a viewing window  9  and a locking device  10  are molded in the coinciding slots  6  and  8  with transparent material. The assembly shown in FIG. 4 is thus a self-contained tubular connector which can be embodied, without further molding procedures, in a stimulator housing. Several examples of the simplified manner of assembling such a stimulator are shown in FIGS. 6 through 11. 
     In the embodiment shown in FIG. 6, a housing  11  has two slightly enlarged regions  12  and  13  at opposite sides thereof, which respectively receive the tube connectors  7 , as shown in FIG.  7 . The tubular connectors  7  are respectively connected to electrode leads  14  and  15 . FIG. 6 shows the housing  11  in completely assembled form, with a top housing half being welded or otherwise joined to a bottom housing half  16 , which is visible in FIG. 7 with the top half removed. As can be seen in FIG. 7, before the top housing half is joined to the bottom housing half  16 , a hybrid circuit  17  and a battery  18  are positioned, together with the tubular connectors, in the bottom housing half  16 . The top housing half then only needs to be fitted over these components, enjoined to the bottom housing half  16 . Moreover, as can be seen in FIGS. 6 and 7, the top and bottom housing halves are identical, i.e., they are not mirror-symmetrical as in a conventional pacemaker housing. Therefore, only one housing half shape needs to be manufactured and maintained in inventory, thereby considerably simplifying manufacturing and assembly. 
     Another embodiment wherein identical housing halves can be employed is shown in FIGS. 8 and 9. In this embodiment, the assembled housing  19  shown in FIG. 8 has two enlarged side portions  20  and  21  from which electrode leads  22  and  23  respectively extend. As can be seen in FIG. 9, wherein the top half of the housing has been removed so as to expose the bottom housing half  24 , tubular connectors  7  are again mounted at opposite sides of the housing, and a hybrid  17  and a battery  18  are positioned therein. Again, the top housing half only needs to be joined to the bottom housing half with all components mounted therein as shown in FIG.  9 . 
     If more electrodes are needed, it would also be possible to arrange two further electrodes in the embodiment shown in FIGS. 8 and 9 at the unoccupied housing regions, generally forming a square in combination with the illustrated electrode leads. 
     The embodiment shown in FIGS. 10 and 11 makes use of a conventionally shaped pacemaker housing having mirror-symmetric housing halves, and thus the advantage of being able to manufacture and maintain a single housing half shape does not apply to the embodiment of FIGS. 10 and 11, but the overall assembly using the self-contained connector tube  7  is still applicable. FIG. 10 shows a conventional posterior housing half  25 , with the tubular connector  7  and the hybrid  17  and the battery  18  mounted therein, electrically connected by lead wires. FIG. 11 shows the completely assembled stimulator, with the front half  26  of the housing welded in place, not only to the posterior housing half  25 , but also to the tubular connector  7 , by means of weld seam  27 . 
     FIG. 5 is a sectional view of one embodiment of a tubular connector  29 , shown mounted in a housing  28  with a lead  30  inserted therein. The housing  28  contains a hybrid circuit  31 , to which the tubular connector  29  is electrically connected by wires  32  and  33 , which are appropriately bonded to the hybrid circuit  31 , and which proceed through openings in the outer sleeve  34  of the tubular connector  29 . As can be seen in FIG. 5, the opposite ends of the outer sleeve  34  of the tubular connector  29  have annular channels therein, so that the tubular connector  29  is held in place by the housing  28 . 
     From one end of the tube  34  (the left side in FIG.  5 ), a ceramic plug  42  is inserted, in which contact rings  38  and  39  have been molded. The ceramic plug  42  has a central bore therein which is shaped to accommodate the lead  30 . The ceramic plug  42  has an annular channel in which a circular spring contact  40  is inserted, in mechanical and electrical contact with the contact  39 . The contact  38  projects beyond the inner terminating end of the plug  42 , and thus an open annular channel is present at that end of the plug  42 , which receives another circular spring contact  40 , in electrical and mechanical contact with the contact  38 . This open end of the plug  42  is closed by a cylindrical component  36 , which is inserted through the other end (the right end in FIG. 5) of the sleeve  34 . The plug  36  has a central bore therein, which may be provided with threads. A resilient locking ring  37  is inserted into the bottom of this bore, and the bore is closed by a plug  35  which is screwed into the threads in the bore of the plug  36 . 
     The lead  30  carries four sealing rings  43 ,  44 ,  45  and  46 . The lead  30  has a first contact surface  47  which, when the lead  30  is inserted in the opening in the tubular connector  29 , makes electrical contact with the contact  41 , to produce an electrical path to the hybrid circuit  31  via the contact  41 , the contact  39  and the wire  32 . The lead  30  also has a second contact surface  48  which, when the lead  30  is inserted in the tubular connector  29 , makes electrical contact with the contact  40 , thereby producing an electrical path to the hybrid circuit  31  via the contact  40 , the contact  38  and the wire  33 . 
     Another embodiment is shown in FIG. 12, wherein a substrate  53  of ceramic material is mounted in a slot  52  of an exterior tube  50  of the tubular connector  49 . The substrate  53  is for the purpose of making electrical connections to the circuitry within the stimulator housing. The exterior tube  50  has a cylindrical bore  51  therein, which receives an end of an electrode lead  57  in a tubular adapter  61 . The tubular adapter  61  has a flanged end  55 , one side  54  of which is hinged so as to be openable to allow the lead  57  to be inserted therein, and can be provided with annular ribs so that when it is closed, as shown in FIG. 12, the lead  57  is firmly held therein. The lead  57  has sealing rings and contact surfaces as described in connection with the embodiment of FIG.  5 . O-rings  56 ,  59  and  60  are provided for sealing purposes. Contacts  53   a  (which are not visible in the sectional plane shown in FIG.  12  and which are therefore schematically indicated by dashed lines) provide an electrical path between the lead  57  and the substrate  53 . 
     Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.