METHOD OF ESTABLISHING A FEEDTHROUGH AND A FEEDTHROUGH IN AN IMPLANTABLE APPARATUS FOR STIMULATING LIVING TISSUE

Abstract: A common feedthrough (18) for both unipolarly and bipolarly connected pacemakers (25), is established by having a sleeve (3) filled with an insulating compound (4), through which a first conductor (5), a second conductor (14) and a third conductor (19) run. The second conductor (14) and the third conductor (19) are linked to each other at one end and the third conductor (19) is connected to the sleeve (3) via a joining element (20). The first conductor (5) is connected to a stimulating pole (6) and to a corresponding terminal (7), the free end of the second conductor (14) is connected to an indifferent pole (10) and the free end of the third conductor (19) is connected to a reference pole (16), whereby the feedthrough (18) is unipolarly connected. When bipolarly connected, the third conductor (19) is cut (32) outside the housing (2), and the second conductor (14) is connected to a terminal (19), corresponding to the indifferent pole (10).

Description: Method of establishing a feedthrouσh and a feedthrough in an i plantable apparatus for stimulating living tissue The invention relates to a method of establishing a feedthrough and a feedthrough in an implantable apparatus for stimulating living tissue, which feedthrough has the function to connect an output, comprising a stimulating pole and an indifferent pole, of a stimulating pulse gene¬ rator inside a housing of the apparatus to an electrode arrangement outside the housing, whereby a sleeve is placed in the wall of the housing, connected to a refe¬ rence pole of the stimulating pulse generator and filled with an insulating compound that surrounds a first conduc¬ tor and a second conductor, which have been inserted into the sleeve in a manner that the first conductor is connectable to the stimulating pole of the stimulating pulse generator and to a corresponding terminal of the electrode arrangement and that the second conductor is connectable to the indifferent pole of the stimulating pulse generator and, when the apparatus is in a bipolar working mode, to a corresponding terminal of the electrode arrangement. It is important for an implantable apparatus for sti¬ mulating living tissue, a pacemaker for example, that no body fluids are allowed to permeat the apparatus as this would result in a cessation of the function of the appa¬ ratus. Therefore, it is necessary for such apparatuses to be well encapsuled. A pacemaker basically comprises two units - a stimula¬ ting pulse generator and an electrode arrangement. The stimulating pulse generator, whose function is to generate stimulating pulses, adapted to optimize a patient's heart function, is well enclosed in a housing. The electrode ar¬ rangement, whose function is to lead and deliver the sti¬ mulating pulses to the heart, generally comprises a con¬ nector and an electrode lead, whose distal end is an electrode tip positioned in the heart and whose proximal end is removably fastened to the connector and at the same time close-fitting. The connector itself is well encap¬ suled with the exception of openings for the proximal end of the electrode lead and for the connection with the sti- ulating pulse generator. It is when the stimulating pulse generator and the con¬ nector are to be brought together that a feedthrough is of use. It shall connect the two units electrically and fit closely between them. Such a pacemaker is known through DE-A-2914034 for example. A pacemaker can work either in a unipolar mode or a bipolar mode. It is hereby known to use identical stimu¬ lating pulse generators but different feedthroughs and electrode arrangements for the two working modes. In the unipolar working mode, a stimulating pulse is generated by the stimulating pulse generator and led from a stimulating pole of the stimulating pulse generator through a conduc¬ tor in the feedthrough to the electrode arrangement and via the electrode arrangement out to the heart. From the heart, the stimulating pulse returns to the stimulating pulse generator via the housing, which is connected to an indifferent pole of the stimulating pulse generator via a sleeve of the feedthrough. In the bipolar working mode, another feedthrough is used, which, apart from the above mentioned conductor, also comprises a second conductor to which the indifferent pole and a ring electrode of the electrode arrangement are connected. The sleeve of the feedthrough is hereby connected to a reference pole of the stimulating pulse generator. A stimulating pulse generated by the stimulating pulse generator is led, as for the unipolar pacemaker, from the stimulating pole via the feedthrough and the electrode lead to the heart, whereby the stimulating pulse returns to the stimulating pulse generator via the ring electrode. An embodiment of the known feedthrough for a unipolar connection is shown in fig 1 and an embodiment of the known feedthrough for a bipolar connection is shown in fig 2. Since the stimulating pulse generator is identical for both unipolar and bipolar pacemakers, the use of two different type of feedthroughs causes a number of techni¬ cal production problems. Two different types of feedthroughs have to be manufac¬ tured and stocked, and, furthermore, it will, after the mounting of the feedthroughs to the stimulating pulse generator, be necessary to keep double stores to separate the two types of semi-manufactured pacemakers from each other. The decision whether unipolar or bipolar pacemakers are to be manufactured must be taken at a comparatively early stage of the production, which results in an increased vulnerability to variations in the actual need of the two types of pacemakers. The object of the invention is to provide a method to establish a feedthrough and a feedthrough, which can be used in both unipolar and bipolar pacemakers and which is easy to manufacture and easy to mount. The problem of providing a method to establish a feed¬ through is inventively solved in that, for the method as described in the introduction, the second conductor is connected to the sleeve by means of a return connector, thereby forming a loop outside the housing, so that the indifferent pole and the reference pole are connected when the apparatus is in a unipolar working mode, and in that, for the bipolar working mode, the return connector part of the loop is cut. The foremost advantage is that this, in a simple way, allows the use of only one type of feedthrough, provided according to the method, in both unipolar and bipolar pacemakers. All that is needed is to cut the return connector part of the second conductor leading to the sleeve in order to have the feedthrough (and the pacemaker) working in a bipolar mode. Therefore, it is not necessary to manufacture and store more than one type of feedthrough, which makes the pacemakers identical in all stages of production up to the point where the connector is to be mounted to the stimulating pulse generator and the feedthrough. The vulnerability to variations in the actual need of unipolar and bipolar pacemakers, respectively, is decreased and an increase in efficienty is obtained. All feedthroughs are connected in the same manner to the stimulating pulse circuit thereby reducing the risk of product errors. The problem of providing a feedthrough is inventively solved in that a feedthrough in an apparatus for stimula¬ ting living tissue, which feedthrough has the function to connect an output, comprising a stimulating pole and an indifferent pole, of a stimulating pulse generator inside a housing of the apparatus to an electrode arrangement outside the housing and which feedthrough comprises a sleeve placed in the housing and connected to a reference pole of the stimulating pulse generator, an insulating compound that fills the sleeve, a first conductor, which is connectable to the stimulating pole of the stimulating pulse generator and runs through the insulating compound in the sleeve out of the housing where it is connectable to a corresponding terminal of the electrode arrangement, and a second conductor, which is connectable to the indif¬ ferent pole of the stimulating pulse generator and runs through the insulating compound in the sleeve out of the housing where it, when the apparatus is to be in a bipolar working mode, is connectable to a corresponding terminal of the electrode device, is characterized in that the se¬ cond conductor is connected to the sleeve via a return connector, thereby forming a loop outside the housing. As mentioned previously, in connection with the method, the feedthrough is directly usable for unipolar pace¬ makers, while for bipolar pacemakers, the return connector part of the loop is cut. The feedthrough according to the invention can be advantageously improved in that a third conductor, which is connected to the reference pole of the stimulating pulse generator, runs through the insulating compound in the sleeve out of the housing where it is connected to the second conductor, thereby forming the loop, and in that the third conductor is connected to the sleeve by means of a joining element. The advantage in this is that when the feedthrough is mounted to the stimulating pulse generator, there is no need for an extra connection to connect the sleeve with the reference pole of the stimulating pulse generator, which simplifies the mounting of the feedthrough. Analogous with what is mentioned previously, for the bipolar connection of the electrode arrangement, the third conductor is cut outside the housing. In connection with this, it may be pointed out that the second conductor and the third conductor can be linked before or after the mounting of the feedthrough to the stimulating pulse generator. The joining element can be placed outside the housing, in the sleeve or inside the housing. The placing of the joining element outside the housing and inside the housing, respectively, simplifies the manufacturing process of the feedthrough. It is irrelevant for the function of the feedthrough if one or several joining elements are used. Another advantage can be obtained for the feedthrough in that the second conductor and the third conductor are a single conductor, which is bent in the shape of a U, and in that the bent part is outside the housing. Hereby, a feedthrough is obtained, which fulfils all that may be required of it to function in accordance with the inven¬ tion and the feedthrough manufacturing process is simpli¬ fied as the special step to link the second conductor and the third conductor is omitted. In the following, the state of the art and embodiments of the feedthrough according to the invention are described in connection with five figures, whereby fig 1 shows a unipolar feedthrough according to the state of the art, fig 2 shows a bipolar feedthrough according to the state of the art, fig 3 shows a first embodiment of the feedthrough accor¬ ding to the invention, fig 4 shows a second embodiment of the feedthrough and fig 5 shows the feedthrough according to fig 3 mounted in a bipolar pacemaker. A feedthrough 1 for unipolar connection according to the state of the art is shown in fig 1. In a partially shown housing 2 in a pacemaker, a sleeve 3 is placed, which encloses an insulating compound 4 through which a conductor 5 runs. One end of the conductor 5 is connected to a stimulating pole 6 of a stimulating pulse generator 26, indicated with a dash-dotted line, in the pacemaker, and the other end is connected to a corresponding terminal 7 of an electrode arrangement 27, indicated with a dash- dotted line, in the pacemaker. Around the case 3, an annular ring 8 is attached, and on the annular ring 8 is mounted a connecting means 9, which is connected to an indifferent pole 10 of the stimulating pulse generator 26 in the pacemaker. A stimulating pulse from the stimulating pulse generator 26 thereby proceeds from the stimulating pole 6 through the conductor 5 to the electrode arrangement 27 and from there through an electrode lead 11 to a heart 12. Thereafter, the stimulating pulse returns via the housing 2 of the pacemaker to the sleeve 3, the annular ring 8, the connecting means 9 and, finally, to the indifferent pole 10 of the stimulating pulse generator 26. Fig 2, similarily, shows a feedthrough 13 for a bipolar connection according to the state of the art. In contrast to the unipolar feedthrough l, the bipolar feedthrough 13 has a second conductor 14, which runs through the insula¬ ting compound 4 in the sleeve 3. This second conductor 14 is connected to the indifferent pole 10 of the stimulating pulse generator 26 and to a corresponding terminal 15 of the electrode arrangement 27. The connecting means 9 is for the bipolar feedthrough 13 connected to a reference pole 16 of the stimulating pulse generator 26 and thereby connects the housing 2 of the pacemaker to the reference pole 16 of the stimulating pulse generator 26 via the sleeve 3, the annular ring 8 and the connecting means 9. A stimulating pulse from the stimulating pulse generator 26 thereby proceeds from the stimulating pole 6 through a first conductor 5 to the electrode arrangement 27 and from there through a first conductor 11a of an electrode lead to the heart 12 and returns via a ring electrode 17 through a second conductor lib of the electrode lead to the second conductor 14 and the indifferent pole 10 of the stimulating pulse generator 26. Fig 3 shows a feedthrough 18, which is adapted to be used for both the unipolar and the bipolar connection in accordance with the invention. As previously, this feedthrough 18 is made up of a sleeve 3 filled with an insulating compound 4. A first conductor 5 runs through the insulating compound 4 in the sleeve 3 and one end of said first conductor 5 is connected to the stimulating pole 6 of the stimulating pulse generator 26 in the pacemaker. A second conductor 14 also runs through the insulating compound 4 in the sleeve 3 and is connected with one end to the indifferent pole 10 of the stimulating pulse generator 26. A third conductor 19 likewise runs through the insulating compound 4 in the sleeve 3 and is connected with one end to the reference pole 16 at the stimulating pulse generator 26 and is also, via a joining element 20, connected to the sleeve 3. In fig 3, the joining element 20 is placed on the same side of the sleeve 3 as the stimulating pulse generator 26, but might as well be placed on the other side of the sleeve 3 or even inside the sleeve 3. It is also possible to use more than one joining element 20. The second conductor 14 and the third conductor 19 are linked to each other at their free ends 21, respectively, outside the housing 2 and thereby form a loop 22. The feedthrough 18 is in fig 3 connected unipolarly to the electrode arrangement 27, which only comprises one terminal 7, to which the first conductor 5 is connected. A bipolar connection with the feedthrough 18 is described below in connection with fig 5. Fig 4 shows a second embodiment of a feedthrough 23 in accordance with the invention. In this case, the second conductor 14 and the third conductor 19 are a single conductor 24, which is bent on the middle. Otherwise, the feedthrough 23 is identical with the feedthrough 18 in fig 3. When connected unipolarly, which is shown in the figure, only the first conductor 5 is connected to a terminal 7 of the electrode arrangement 27. Bipolar connection of the feedthrough 23 is carried out in a manner analogous with the bipolar connection of the feedthrough 18. The positioning, according to the present invention, of the feedthrough 18 in fig 3 in a bipolar pacemaker 25, is schematically shown in fig 5. In order to emphasize the essential parts of the pacemaker 25, they have been unpro- portionally altered. The pacemaker 25 basically comprises two parts; the stimulating pulse generator 26 within the housing 2 and the electrode arrangement 27. As described above, the stimulating pulse generator 26 comprises a sti- mulating pole 6, an indifferent pole 10 and a reference pole 16. The electrode arrangement 27 comprises a conduc¬ tor 28 and an electrode lead 29. The proximal end 30 of the electrode lead 29 is removably fastened to the con- nector 28 and in its distal end there is an electrode tip 31 and a ring electrode 17. The feedthrough 18 is placed in the housing 2 of the pacmaker 25 and, through the first conductor 5, connects the stimulating pole 6 to the corresponding terminal 7 of the electrode arrangement 27, which carries stimulating pulses via the electrode lead 29 to the electrode tip 31. The feedthrough 18, through the second conductor 14, also connects the indifferent pole 10 to the corresponding terminal 15 of the electrode arrange¬ ment 27 and, via the electrode lead 29, to the ring elec- trode 17. The third conductor 19 of the feedthrough 18 connects the sleeve 3 to the reference pole 16 via the joining element 20 and is cut 32, in the part that is outside the housing 2, from its link to the second con¬ ductor 14. 9 claims 5 figures

Claims: Claims 1. Method of establishing a feedthrough (18) in an implantable apparatus for stimulating living tissue, which feedthrough (18) has the function to connect an output, comprising a stimulating pole (6) and an indifferent pole (10), of a stimulating pulse generator (26) inside a housing (2) of the apparatus to an electrode arrangement (27) outside the housing (2), whereby a sleeve (3) is placed in the wall of the housing (2), connected to a reference pole (16) of the stimulating pulse generator (26) and filled with an insulating compound (4) that surrounds a third conductor (5) and a second conductor (14), which have been inserted into the sleeve (3) in a manner that the first conductor (5) is connectable to the stimulating pole (6) of the stimulating pulse generator (26) and to a corresponding terminal (7) of the electrode arrangement (27) and that the second conductor (14) is connectable to the indifferent pole (10) of the stimula- ting pulse generator (26) and, when the apparatus is in a bipolar working mode, to a corresponding terminal (15) of the electrode arrangement (27), c h a r a c t e¬ r i z e d i n that the second coductor (14) is connec¬ ted to the sleeve (3) by means of a return connector, thereby forming a loop (22) outside the housing (2) so that the indifferent pole (10) and the reference pole (16) are connected when the apparatus is in a unipolar working mode and in that, for the bipolar working mode, the return connector part of the loop (22) is cut. 2. Feedthrough (18) in an apparatus for stimulating living tissue, which feedthrough (18) has the function to connect an output, comprising a stimulating pole (6) and an indifferent pole (10) , of a stimulating pulse generator (26) inside a housing (2) of the apparatus to an electrode arrangement (27) outside the housing (2) and which -j-j feedthrough (18) comprises a sleeve (3) placed in the housing (2) and connected to a reference pole (16) of the stimulating pulse generator (26), an insulating compound (4) that fills the sleeve (3), a first conductor (5), which is connectable to the stimulating pole (6) of the stimulating pulse generator (26) and runs through the insulating compound (4) in the sleeve (3) out of the housing (2) where it is connectable to a corresponding terminal (7) of the electrode arrangement (27), and a second conductor (14), which is connectable to the indifferent pole (10) of the stimulating pulse generator (26) and runs through the insulating compound (4) in the sleeve (3) out of the housing (2), where it, when the ap¬ paratus is to be in a bipolar working mode, is connectable to a corresponding terminal (15) of the electrode arrange¬ ment (27), c h a r a c t e r i z e d i n that the second conductor (14) is connected to the sleeve (3) via a return connector, thereby forming a loop (22) outside the housing (2) (fig 3). 3. Feedthrough according to claim 2, c h a r a c ¬ t e r i z e d i n that the return connector part of the loop (22) is cut (32) when the apparatus is to be in the bipolar working mode. 4. Feedthrough according to claim 2, c h a r a c ¬ t e r i z e d i n that the return connector comprises a third conductor (19), which is connected to the reference pole (16) of the stimulating pulse generator (26) and runs through the insulating compound (4) in the sleeve (3) out of the housing (2) , where it is connected to the second conductor (14), thereby forming the loop (22), and in that the third conductor (19) is connected to the sleeve (3) by means of a joining element (20). 5. Feedthrough according to claim 4, c h a r a c ¬ t e r i z e d i n that the third conductor (19) is cut outside the housing (2) when the apparatus is to be in the bipolar working mode. 6. Feedthrough according to claim 4 or 5, c h a r a c t e r i z e d i n that the joining means (20) is placed outside the housing (2). 7. Feedthrough according to claim 4 or 6, c h a r a c t e r i z e d i n that the joining means (20) is placed inside the sleeve (3). 8. Feedthrough according to claim 4 or 5, c h a r a c t e r i z e d i n that the joining means (20) is placed inside the housing (2). 9. Feedthrough according to one of the claims 4 to 8, c h a r a c t e r i z e d i n that the second conduc- tor (14) and the third conductor (19) are a single con¬ ductor (24), which is bent in the shape of a ϋ, and in that the bent part is outside the housing (2) (fig 5).

Inventors: DAHLBERG KENNETH, JARL PER, DAHLBERG, KENNETH, JARL, PER
Applicants: SIEMENS AG, SIEMENS ELEMA AB, SIEMENS AKTIENGESELLSCHAFT, SIEMENS-ELEMA AB
Application year: 1991
Main classification: A61N1
IPC codes: A61N1