Electrode for an implantable medical device for stimulating a human or animal heart

Abstract

The invention relates to an electrode (20) for an implantable medical device for stimulating a human or animal heart. According to an aspect, the electrode (20) comprises at least four electrode poles (201, 202, 203, 204, 205) and a single connector (208) comprising an individual connector pole (209, 210, 211, 212, 213) for each electrode pole (201, 202, 203, 204, 205).

Description

[0001] Electrode for an implantable medical device for stimulating a human or animal heart

[0002] The present invention relates to an electrode for an implantable medical device according to the preamble of claim 1 and to an implantable medical device comprising such an electrode according to claim 11.

[0003] Implantable medical devices for stimulating a human or animal heart can feature different functionalities. To give an example, a CRT-D device is designed and arranged to accomplish a cardiac re synchronization therapy and a defibrillation of the patient’s heart. Such a CRT-D device typically has three electrodes, namely a combined right ventricular defibrillation and stimulation electrode, a right atrial stimulation and sensing electrode and a left ventricular coronary sinus electrode. Some manufacturers like BIOTRONIK also offer a more complex right ventricular electrode that integrates the atrial sensing functionality into the right ventricular stimulation electrode. However, still in this case, two electrodes are necessary to be implanted in or at the patient’s heart. Thus, the solutions known from prior art require for a biventricular stimulation at least two ventricular electrodes. This requires a very big connecting block (header) of the stimulation generator of the implantable medical device being able to receive at least two, but typically even three electrode connectors. Such a big connecting block complicates the implantation of the implantable medical device.

[0004] If the implantable medical device is designed and arranged as a CRT-P device, i.e., a device for cardiac re synchronization therapy and pacing (but no defibrillation), the general setup is almost identical to the previously described CRT-D device. However, the CRT-P device does not comprise a defibrillation electrode. Nonetheless, CRT-P devices known from prior art typically require three distinct electrodes and an accordingly big connector block of the stimulation generator to connect these electrodes to the stimulation generator.

[0005] If the implantable medical device is designed and arranged as a device for employing a two-chamber therapy, it is also necessary to implant two distinct electrodes into the patient’s heart. One electrode is guided into the right atrium, and the other is guided into the left ventricle. Both electrodes need to be connected with the stimulation generator, i.e., the implantable pulse generator. For this purpose, the implantable pulse generator typically comprises at least two connecting sockets. Like in case of a three-socket connecting box, this requires a significant amount of space. As outlined above, prior art already teaches a specific variant of integrated electrodes that uses a proximal bipole for sensing electric signals in the patient’s right atrium. Then, this variant of the ventricular electrode already takes over the functionality of the atrial electrode. However, this electrode comprises a switch with two plugs to be able to be connected with a regular two-chamber stimulation system. Thus, the integration of the atrial electrode into the ventricular electrode does not alter the space requirement of the connector box of the stimulation generator.

[0006] It is an object of the present invention to provide an electrode for an implantable medical device for stimulating a human or animal heart that allows an easy implantation in the heart and an easy implantation of a housing of an implantable medical device to which the electrode is connected.

[0007] This object is achieved with an electrode for an implantable medical device for stimulating a human or animal heart having the features of claim 1. Such an electrode comprises at least four electrode poles and a connector. The connector comprises at least four connector poles, wherein at least three of the four electrode poles are each associated with one of the four connector poles. Moreover, the electrode comprises not more than two connectors. Thus, in case of four electrode poles, the electrode may comprise a single connector, wherein each of the at least four connector poles is associated with one of the four electrode poles. In another embodiment the electrode may comprise five electrode poles and two connectors, wherein a first connector of the two connectors has at least four connector poles and a second connector of the two connectors has at least two connector poles. In this case three of the five electrode poles may be each associated with one of the four connector poles of the first connector and two of the five electrode poles may be associated with the two connector poles of the second connector. The individual connector poles are insulated against each other. Typically, each connector pole is connected to only a single electrode pole.

[0008] Such an electrode enables a ventricular CRT-D therapy or CRT-P therapy with only a single electrode lead. Likewise, the electrode can be used as VDD electrode (i.e., an electrode enabling an implantable pulse generator to be operated in its VDD mode featuring ventricular stimulation, biventricular sensing, and a dual operational mode (inhibition and triggering). Since the electrode comprises not more than two connectors, it also requires only a housing of an implantable medical device comprising one or two header ports for connecting the electrode to the housing instead of three. Consequently, an according implantable medical device can be designed in a significant smaller way than prior art implantable medical devices can.

[0009] In an embodiment, the electrode comprises a single connector, wherein each of the at least four connector poles of the single connector is associated with one of the at least four electrode poles. Since the electrode comprises a single connector only, it also requires only a housing of an implantable medical device comprising a single header port for connecting the electrode to the housing. Consequently, an according implantable medical device can be designed in a significant smaller way than prior art implantable medical devices can. The electrode does not require any switch that significantly complicates implantation of the electrode. Rather, in an embodiment, the electrode is designed and arranged in a switch-free manner with an essentially constant cross-section from its distal electrode tip to its proximal electrode connector, thus significantly facilitating its implantation.

[0010] In an embodiment, the first electrode pole of the at least four electrode poles is a helical electrode pole or helix electrode pole. This helix electrode pole is designed and configured to be secured within cardiac tissue. For this purpose, the helix electrode pole can be turned into the cardiac tissue. Alternatively, the first electrode pole may be a fixation anchor electrode pole. In an embodiment, the cardiac tissue into which the helix electrode pole or the fixation anchor electrode pole is to be secured is the apex. In another embodiment, the cardiac tissue into which the helix electrode pole or the fixation anchor electrode pole is to be secured is the septum. After having implanted the first electrode pole into the cardiac tissue, in particular into the septum, in particular into the deep septum, it is possible to achieve an effective stimulation of the left ventricle even if no electrode is directly placed within the left ventricle or on an outside thereof (as in case of prior art left ventricular stimulation electrodes). An implantation of the helix electrode pole or the fixation anchor electrode pole in the deep septum at a position distally of a left branch block enables a left bundle branch area pacing (LBBAP) without requiring a separate left ventricular electrode.

[0011] In an embodiment, the helix electrode pole is designed as fixed fixing helix. In another embodiment, the helix electrode pole is designed as an unscrewable fixing helix. Either design is particularly appropriate for fixing the helix electrode pole within cardiac tissue, in particular within the (deep) septum of the patient’s heart.

[0012] In an embodiment, the fixation anchor electrode pole may comprise a passive fixation anchor for anchoring a distal end of the electrode in the cardiac tissue.

[0013] In an embodiment, the first electrode pole of the at least four electrode poles is a distal electrode pole, wherein the electrode comprises a separate fixing element. This fixing element is designed and configured to be secured within cardiac tissue, in particular within the apex or the septum, in particular the deep septum, of the patient’s heart. The fixing element is electrically insulated against the first electrode pole. The fixing element is, in an embodiment, designed as fixing helix or a fixation anchor. By securing the fixing element into the cardiac tissue it is possible to stimulate the patient’s cardiac tissue with the first electrode pole in a similar way as explained above with respect to the embodiments in which the first electrode pole is designed as helix electrode pole or a fixation anchor electrode pole, respectively. Thus, also in case of a first electrode pole and a separate fixing element, it is possible to use the first electrode pole for LBBAP. Consequently, also the first electrode pole of the presently described embodiment is very well suited to be used for left ventricular stimulation without requiring a separate left ventricular stimulation electrode.

[0014] In an embodiment, a second electrode pole of the at least four electrode poles is a ring electrode or a shock coil. In this context, the second electrode pole is located proximally of the first electrode pole. If the second electrode pole is designed as shock coil, the electrode is particularly appropriate to be used as electrode for a CRT-D device. The shock coil is particularly appropriate to deliver a defibrillation shock to the patient’s heart, i.e., to deliver a defibrillation therapy. If the electrode is not to be intended to be used for a CRT-D device, but rather for a CRT-P device, the second electrode pole is typically designed as ring electrode pole since the delivery of a defibrillation therapy is not intended. Such a design of the second electrode pole as ring electrode pole enables an implantation of the first electrode pole and the second electrode pole within cardiac tissue, in particular within the (deep) septum of the patient’s heart. Then, the polarity of the individual electrode poles is changeable. It is possible to stimulate in a unipolar manner (the first electrode pole against a housing of an implantable medical device) or in a bipolar manner (the first electrode pole against the second electrode pole). In such a set-up, the first electrode pole (optionally designed as helix electrode pole or fixation anchor electrode pole) is typically used as cathode, wherein the second electrode pole or ring electrode pole is typically used as counter electrode. The factual stimulation site will then be the first electrode pole which is, in the implanted state of the electrode, even closer positioned to the left ventricle and can thus effectuate a left ventricular stimulation in a very appropriate way, in particular as LBBAP.

[0015] In an embodiment, the second electrode pole is a shock coil and has a surface of at least 150 mm2, in particular at least 175 mm2, in particular at least 200 mm2, in particular at least 225 mm2, in particular at least 250 mm2. Such a surface enables a sufficiently big shock pulse to be delivered by the shock coil to achieve an efficient cardiac defibrillation of the patient’s heart.

[0016] In an embodiment, a distance between a distal end of the second electrode pole and a proximal end of the first electrode pole is at least 10 mm, in particular at least 15 mm, in particular at least 20 mm, in particular at least 30 mm, in particular at least 40 mm, in particular at least 50 mm. In an embodiment, the distance between the distal end of the second electrode pole and the proximal end of the first electrode pole lies in a range from 10 mm to 100 mm, in particular from 20 mm to 90 mm, in particular from 30 mm to 80 mm, in particular from 40 mm to 70 mm, in particular from 50 mm to 60 mm. Such a distance between the first electrode pole and the second electrode pole is particularly appropriate if the second electrode pole is designed as shock coil. In contrast, if the second electrode pole is designed as ring electrode pole and is intended to form together with the first electrode pole a bipole that is to be implanted within cardiac tissue, in particular within the septum of the patient’s heart, a smaller distance between the first electrode pole and the second electrode pole is also conceivable.

[0017] In an embodiment, a third electrode pole and a fourth electrode pole of the at least four electrode poles are ring electrode poles. In this context, the third electrode pole and the fourth electrode pole are designed and configured such that one of the third and fourth electrode poles serves as counter electrode pole for the respective other electrode pole. In addition, the third electrode pole is located proximally from the second electrode pole, and the fourth electrode pole is located proximally from the third electrode pole. Expressed in other words, the third electrode pole and the fourth electrode pole form a bipolar electrode pole arrangement that is located proximally of the second electrode pole. By such an arrangement, it is possible that the third electrode pole and the fourth electrode pole are located, in an implanted state of the electrode, in the right atrium of the patient’s heart. Then, the third electrode pole and the fourth electrode pole can sense atrial signals to be used for stimulating the right ventricle and / or the left ventricle of the patient’s heart by the first electrode pole and / or the second electrode pole. Thus, all sensing and stimulation functionalities of an implantable medical device are integrated within a single electrode. This has the effect that lead-to-lead interactions between different electrode leads are completely omitted. Rather, the single electrode employing both sensing and stimulation functionalities enables a particularly safe operation of an implantable medical device and also enables a much easier implantation than in case of two or three different electrodes.

[0018] If the electrode is designed as a VDD electrode, it also enables a VAT operation, i.e., a ventricular stimulation depending on atrial sensing in an operational mode that allows only triggering. The stimulation of the ventricle on the basis of the atrial cardiac rhythm is a particularly physiologic possibility of employing ventricular stimulation. Due to the possibility of implanting the electrode within the (deep) septum of the patient’s heart, the implantation of the electrode is also particularly facilitated with respect to prior art systems requiring an additional, coronary sinus electrode placed on an outside of the left ventricle.

[0019] In an embodiment, the third electrode pole is implemented as a distal shock coil and the fourth electrode pole is implemented as a proximal shock coil.

[0020] In an embodiment, the electrode lead of the electrode has a diameter equal to or smaller than 6 F, in particular equal to or smaller than 5 F, in particular equal to or smaller than 4 F. Such dimension of the electrode lead also facilitates the implantation of the whole electrode. In an embodiment, at least one connector of the electrode is realized according to the DF4 standard. Such a design of the connector is particularly appropriate if the electrode is designed for CRT-D applications, i.e., if the second electrode pole is configured as shock coil.

[0021] In an embodiment, at least one connector of the electrode is realized according to the IS4 standard. Such a configuration of the connector is particularly appropriate if the electrode is intended to be used for CRT-P applications, i.e., if the second electrode pole is designed as ring electrode pole.

[0022] In an embodiment, where the electrode comprises two connectors, the first connector may be realized according to the IS4 or the DF4 standard and the second connector may be realized according to the IS1 standard.

[0023] In an embodiment, the electrode comprises at least five electrode poles, in particular exactly five electrode poles. In this case, the only connector of the electrode comprises also at least five connector poles, in particular exactly five connector poles (one connector pole for each electrode pole). An electrode having five electrode poles can combine the precedingly explained embodiments, i.e., it can feature both a distal bipole to be implanted into cardiac tissue such as the septum and a defibrillation electrode located between the distal bipole (used for ventricular sensing and stimulation) and the proximal bipole (used for atrial sensing and optionally stimulation). In such an embodiment, the second electrode pole of the at least five electrode poles is a ring electrode pole, and the fifth electrode pole of the at least five electrode poles is a shock coil. In this embodiment, the fifth electrode pole is located proximally from the second electrode pole, but distally of the third electrode pole, i.e., between the second and the third electrode pole.

[0024] In one embodiment, if the fifth electrode pole is a shock coil, a distance between a distal end of the fifth electrode pole and a proximal end of the first electrode pole lies in a range from 10 mm to 30 mm, in particular from 10 mm to 15 mm. Preferably the distance between a distal end of the fifth electrode pole and a proximal end of the first electrode pole is 13 mm. The length of the fifth electrode pole or shock coil along the electrode 20 may lie in the range from 40 mm to 70 mm, in particular from 45 mm to 55 mm.

[0025] In an embodiment, the proximal bipole (containing the third electrode pole and the fourth electrode pole) is arranged so that it is floating in the atrium after implantation of the electrode. Floating means that the bipole is not (additionally) fixed to the tissue. Thereby, the bipole may float freely in the atrium or rest against the wall of the atrium. In an embodiment, the fifth connector pole is configured as ring electrode and is located distally from the other four connector poles. In an embodiment, the first four connector poles are designed to be mechanically compatible to the IS4 standard. In the IS4 standard, a first connector pole is arranged as tip connector pole at the proximal end of the connector (which is, at the same time, the proximal end of the electrode), wherein the second, third and fourth connector poles are designed as ring connector poles having a specified diameter. In an embodiment, the diameter of the fifth connector pole is bigger than the diameter of the second to fourth connector pole. Then, a socket for receiving such five-pole connector is downwards compatible to an IS4 connector; a fifth socket pole will simply not contact any connector pole of an IS4 connector.

[0026] In an embodiment, the pin connector pole (first connector pole or innermost connector pole) is electrically connected with the tip electrode pole (first electrode pole). The tip electrode pole can be configured as helical electrode pole, as outlined above. It serves for sensing ventricular signals and stimulating the right and / or left ventricle of the patient’s heart. The second connector pole (first connector ring pole) is electrically connected to the second electrode pole or ring electrode pole that is intended to be implanted within cardiac tissue, in particular within the apex or the (deep) septum of the patient’s heart. This ring electrode pole serves together with the tip electrode pole as a distal dipole and thus serves for sensing ventricular signals and stimulating the right and / or left ventricle of the patient’s heart.

[0027] The third connector pole (second connector ring pole) is electrically connected with the fifth electrode pole (distal shock coil). The fifth electrode pole serves for delivering a defibrillation therapy to the patient’s heart.

[0028] The fourth connector pole (third connector ring pole) is electrically connected to one of the third and fourth electrode poles. The fifth connector pole (fourth connector ring pole) is electrically connected to the respective other of the third and fourth electrode poles. As explained above, the third and fourth electrode poles are intended to be positioned, in an implanted state of the electrode, within the right atrium of the patient’ s heart. They serve for sensing atrial signals that are afterwards used for triggering ventricular stimulation of the patient’s heart.

[0029] In an embodiment, a distance between a distal end of the fourth electrode pole and a proximal end of the first electrode pole lies in a range from 100 mm to 200 mm, in particular from 100 mm to 140 mm, in particular from 100 mm to 125 mm.

[0030] In one embodiment, the distance between the facing ends of the third electrode pole and the fourth electrode pole is in the range from 10 mm to 20 mm, in particular from 10 mm to 13 mm. In an embodiment, the connector of the electrode comprises a first connector pole designed as nonpin connector pole that is intended to electrically connect with a socket pin pole, wherein the remaining four connector poles are designed as ring connector poles having all the same diameter. If this five- pole connector is guided into an according socket, the tip connector pole will get in contact with the pin pole of the socket. Then, an electric contact between the individual ring connector poles with corresponding socket connector poles is made possible. If, however, a connector having a pin-like proximal connector pole is inserted into the same socket, the pin of the connector will interact with the pin of the socket such that the ring connector poles will not be positioned opposite the corresponding socket poles so that no electrical contact between the second to fifth connector poles with a corresponding socket pole will be made possible. By such an arrangement, an effective protection against confusion of different connectors is realized.

[0031] In an embodiment, the electrode comprises a drug-eluting reservoir in a distal region of the electrode. The distal region of the electrode typically comprises the distal third of the overall length of the electrode, in particular the distal 25%, in particular the distal 20%, in particular the distal 15%, in particular the distal 10%, in particular the distal 5% of the electrode’s length. This drug-eluting reservoir contains, in an embodiment, a drug reducing or preventing a temporal stimulation threshold increase that is typically observed after implantation of an electrode. In an embodiment, the drugeluting reservoir is refillable. This facilitates an explantation and novel implantation of the electrode.

[0032] In an aspect, the present invention relates to an implantable medical device for stimulating a human or animal heart. Such a device comprises a stimulation unit configured to stimulate a human or animal heart. It further comprises a detection unit configured to detect an electric signal of the same heart. According to this aspect of the present invention, the implantable medical device comprises an electrode according to the preceding explanations as its only electrode. In this context, the electrode forms part of the stimulation unit and of the detection unit.

[0033] As already explained above, an electrode with at least four electrode poles having only two or even only a single connector comprising one connector pole for each electrode pole necessitates only two sockets or a single socket, respectively, within a header of a housing of the implantable medical device into which the connector is to be inserted. Consequently, the header and thus the overall implantable medical device can be designed much smaller than devices known from prior art. Consequently, only a significantly smaller pocket for implanting the implantable medical device is needed than in case of prior art devices. The patient will be less impaired by such a smaller device than by prior art devices. In addition, the long-term risk of infections of smaller pockets is smaller than that of bigger pockets. In case the electrode is a switch-free electrode and it comprises only a single connector, it can be much better pushed and turned during the implantation procedure. In particular upon placing the electrode into the pocket for the housing of the implantable medical device, it can be much easier wound up since no additional connector or switch impedes this procedure. Establishing a connection between the electrode and the header of the implantable medical device is much easier than according to prior art techniques since the user is not required to take care of the specific orientation of a switch or of the electrode connector. Rather, the electrode connector is, in an embodiment, designed in a rotation symmetric way.

[0034] In case the electrode only comprises a single connector, confusion of different connectors is completely prevented. Due to its small dimensions, the electrode is also less bulky in its implanted state and is typically not visible through the patient’s skin. The risk of an electrode abrasion at the housing of the implantable medical device is also significantly reduced since the switch-free electrode is subject to less restrictions in its movement in the patient’s body than an electrode having a switch or having more than one connector is. Finally, the patient’s risk upon box change is significantly smaller since the switch-free electrode having only a single connector is significantly easier to uncover for explantation purposes.

[0035] In an embodiment, the implantable medical device is a device for cardiac re synchronization therapy and defibrillation (CRT-D device), a device for cardiac re synchronization therapy and pacing (CRT- P device), or an implantable pulse generator (IPG) for an anti-bradycardic therapy. All of these devices will take significant advantage of the presently described electrode due to the above-described properties and features of this electrode.

[0036] In an embodiment, the implantable medical device comprises a header having only a single electrode connector receiving socket (also referred to as electrode connecting port or simply connecting port). While there are some specific advantages if the electrode is combined with a stimulation generator having two connecting ports, the specific advantages of an arrangement comprising of a stimulation generator and the presently described electrode are particularly realized if the header only comprises a single connecting port.

[0037] In an embodiment with a single connecting port, the electrode connector receiving socket has at least five socket poles. The five socket poles are, in particular, disposed in series. The electrode connector receiving socket is adapted to receive a five-pole electrode connector whose connector poles are formed and disposed in series in accordance with the electrode connector receiving socket. At least four innermost socket poles of the at least five socket poles are mechanically compatible with the IS4 or DF4 standard. An outermost socket pole may have a larger diameter than the remaining, innermost socket poles. The innermost socket pole may connect to the tip of the connector, when the connector is inserted into the socket. In this way, a four-pole connector, in particular an IS4- or a DF4-standard connector, may be compatible with the five-pole socket.

[0038] In an embodiment, the implantable medical device may automatically detect whether a five-pole or a four-pole electrode has been connected to the socket and may automatically configure the socket poles in accordance with the connected electrode.

[0039] In an embodiment, the automatic determination of the connected electrode is implemented by an impedance measurement. A selection of a type of an electrode may be set or changed manually by a user.

[0040] In an embodiment, a respective electrode connection feature is indicated by a label on the housing.

[0041] In an embodiment, the electrode connector receiving socket may be implemented as a five-pole electrode connector receiving socket, wherein an innermost socket pole is a pin socket pole for connecting to a pin of a connector, and wherein the remaining four socket poles all have a same diameter. In this embodiment, the electrode connector receiving socket is mechanically incompatible with the IS4 and DF4 standards and it is thus prevented that an IS4- or a DF4-standard electrode can be inserted into the socket right up to the pin socket pole which prevents connecting an IS4-or a DF4 electrode accidentally to the five-pole connector.

[0042] In an embodiment, the electrode comprises a first electrode pole, a second electrode pole, a third electrode pole, and a fourth electrode pole. In addition, the implantable medical device further comprises a processor and a memory unit. The memory unit comprises a computer-readable program that causes the processor to perform the steps explained in the following when being executed on the processor.

[0043] First, atrial cardiac signals are sensed with the third electrode pole and the fourth electrode pole. Alternatively, ventricular cardiac signals are sensed in addition to the atrial cardiac signals with the first and second electrode poles. Subsequently, an anti -tachycardic therapy is provided by emitting an electric pulse by the first and / or the second electrode pole. Alternatively or additionally, a cardiac re synchronization therapy is provided by emitting an electric pulse by the first and / or the second electrode pole. Alternatively or additionally, an anti -brady cardie therapy is provided by emitting an electric pulse by the first and / or the second electrode pole. In this context, the anti-tachycardic therapy, the cardiac re synchronization therapy and / or the anti-bradycardic therapy are provided in response to the sensed atrial cardiac signals and / or ventricular cardiac signals so that the ventricular stimulation is triggered by the previously sensed atrial activity and / or ventricular activity and is applied to the patient’s heart with a temporal delay with respect to the sensed atrial activity.

[0044] In an embodiment, the anti-tachycardic therapy comprises or consists of a defibrillation shock. In an embodiment, the implantable medical device is designed and arranged to provide, with its stimulation unit, a maximum shock energy of at least 30 J, in particular at least 35J to 40J, in particular 37J or 39J, in particular at least 50 J.

[0045] In an aspect, the present invention relates to a method of implanting an implantable medical device according to the preceding implementations in a patient in need thereof. The method comprises the steps explained in the following.

[0046] In one method step, the electrode of the implantable medical device is guided into the right ventricle of the patient’s heart.

[0047] In another method step, a distal tip of the electrode is fixed within the septum of the patient’s heart or in the apex of the patient’s heart. This fixing is done such that a first electrode pole is located within the septum or the apex, respectively. A second electrode pole is, in a first alternative, also implanted such that it is located within the septum (if the first electrode pole is located within the septum) or within the apex (if the first electrode pole is located within the apex), respectively. According to a second alternative, the second electrode pole is located within the right ventricle. A third electrode pole as well as a fourth electrode pole are located, after implantation, in the right atrium of the patient’s heart.

[0048] In another method step, the electrode is connected with its connector or connectors, respectively, to a header of the housing of the implantable medical device. After this connection, the electrode forms part of the stimulation unit and of the detection unit of the implantable medical device.

[0049] In a further method step, the housing is implanted at an appropriate site outside the patient’s heart within the patient’s body. This is typically done in a pocket specifically provided for the implantable medical device, e.g., within the area of the patient’s clavicle, i.e., in a subclavian manner.

[0050] It is of no specific importance, in which order the precedingly mentioned implantation steps are performed. Therefore, the order of the present description is not to be construed in a limiting way.

[0051] The implantation of this implantable medical device is much easier than an implantation of the prior art devices since the electrode comprises only one or two connectors, instead of three, and the housing of the implantable medical device can be designed in a much smaller way than housings of prior art devices since the header of the implantable medical device only requires one or two ports for receiving the one or two connectors of the electrode, respectively.

[0052] All embodiments of the electrode can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the implantable medical device and to the method. Likewise, all embodiments of the implantable medical device can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the electrode and to the method. Finally, all embodiments of the method can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the electrode and to the implantable medical device.

[0053] Further details of aspects of the present invention will be explained in the following making reference to exemplary embodiments and accompanying Figures. In the Figures:

[0054] Fig. 1A shows a prior art CRT-D system implanted into a human heart;

[0055] Fig. IB shows a prior art CRT-P system implanted into a human heart;

[0056] Fig. 2 shows an embodiment of a four-pole CRT-D electrode implanted into a human heart;

[0057] Fig. 3A shows an embodiment of a four-pole CRT-P electrode implanted into a human heart;

[0058] Fig. 3B shows a detail of the electrode of Fig. 3A;

[0059] Fig. 4A shows an embodiment of a five-pole CRT-D electrode implanted into a human heart;

[0060] Fig. 4B shows a detail of the connector of the electrode of Fig. 4A;

[0061] Fig. 5 shows a prior art implantable pulse generator with a prior art VDD electrode implanted into a human heart; and

[0062] Fig. 6 shows an embodiment of an implantable medical device comprising a VDD electrode having a four-pole connector; and

[0063] Fig. 7 shows another embodiment of a five-pole CRT-D electrode implanted into a human heart. Figure 1A shows a human heart 1 comprising a right atrium 2, a right ventricle 3, a left atrium 4, and a left ventricle 5. A prior art device for cardiac re synchronization therapy and defibrillation (CRT-D device) 6 is implanted into the heart 1. This CRT-D device comprises a stimulation generator 7 having a header 70. The header 70 comprises three header ports, each of which serves for receiving an individual electrode. Thus, the CRT-D device 6 comprises three electrodes, namely a right ventricular stimulation and shock electrode 8, a right atrial stimulation and sensing electrode 9, and a left ventricular stimulation and sensing electrode 10.

[0064] The right ventricular stimulation and shock electrode 8 is implanted into the right ventricle 3, wherein a tip 80 of the right ventricular stimulation and shock electrode 8 is placed close to the apex 11 or is implanted into the apex 11 of the patient’s heart 1. The right ventricular stimulation and shock electrode 8 furthermore comprises a shock coil 81 that is located proximally of the tip 80 of the right ventricular stimulation and shock electrode 8 and is situated, in the implanted state of the right ventricular stimulation and shock electrode 8, within the right ventricle 3.

[0065] The right atrial stimulation and sensing electrode 9 is implanted into the right atrium 2 and is secured within the cardiac tissue surrounding the right atrium 2. The left ventricular stimulation and sensing electrode 10 is guided into a coronary vein and placed outside the left ventricle 5 to be able to stimulate the left ventricle 5.

[0066] It is apparent from Figure 1A that the implantation procedure of the CRT-D device 6 is rather complicated. In addition, the header 70 of the stimulation generator 7 requires a significant amount of space to be able to house the three electrodes 8, 9, 10.

[0067] Figure IB shows a prior art CRT-P system 6 implanted into human heart 1. In this and in all following Figures, similar elements will be denoted with the same numeral reference. This CRT-P system 6 has a similar set-up as the CRT-D system 6 shown in Figure 1A. The only difference is that the CRT-P system 6 of Figure 1 B does not comprise a right ventricular stimulation and shock electrode, but rather a right ventricular stimulation electrode (without the ability of providing shocks for defibrillation). All other elements of this CRT-P system 6 are identical or closely similar to the elements of the CRT-D system 6 shown in Figure 1 A. Therefore, reference is made to the explanations given above with respect to Figure 1 A.

[0068] Figure 2 shows a human heart 1 into which a four-pole CRT-D electrode 20 is implanted. This CRT- D electrode 20 is guided through the upper vena cava 12 and the right atrium 2 into the right ventricle 3. Here, it is anchored at a deep position of the septum 13 separating the right ventricle 3 and the left ventricle 5 from each other. For the purpose of proper fixing the CRT-D electrode 20, a first electrode pole 201 of this CRT-D electrode 20 is designed as helical electrode pole. It is screwed into the septum 13 so that it almost reaches the left ventricle 5 (but still stays within the septum 13).

[0069] The CRT-D electrode 20 further comprises a second electrode pole 202 that is designed as shock coil. It is located, in the implanted state of the CRT-D electrode 20, within the right ventricle 3 and is able to provide a shock pulse to the heart 1 to achieve a defibrillation of the heart 1 in case of a tachycardic episode.

[0070] The CRT-D electrode 20 furthermore comprises a third electrode pole 203 and a fourth electrode pole 204 that form together a bipole 206 (i.e., one of the third electrode pole 203 and the fourth electrode pole 204 serves as counter electrode for the respective other electrode pole). Since the third electrode pole 203 is located proximally of the second electrode pole 202 and since the fourth electrode pole 204 is located proximally of the third electrode pole 203, the bipole 206 is also referred to as proximal bipole 206. The proximal bipole 206 serves for sensing atrial signals of the heart 1 to be able to apply ventricular stimulation by the first electrode pole 201 and / or the second electrode pole 202 in response to the sensed atrial signals.

[0071] Preferably, the proximal bipole 206 is arranged so that it is floating in the atrium 2 after implantation of the electrode 20. Floating means that the bipole 206 is not (additionally) fixed to the cardiac tissue. Thereby, the bipole 206 may float freely in the atrium 2 or rest against the wall of the atrium 2. The distance between the facing ends of the third electrode pole 203 and the fourth electrode pole 204 (forming the bipole 206) is in the range from 10 mm to 20 mm, in particular from 10 mm to 13 mm.

[0072] The distance between a distal end of the fourth electrode pole 204 and a proximal end of the first electrode pole 201 may lie in a range from 100 mm to 200 mm, in particular from 100 mm to 140 mm, in particular from 100 mm to 125 mm.

[0073] The single CRT-D electrode 20 may be connected via a single electrode connector (not shown here) to a header of a stimulation generator. In this case, the single electrode connector has four connector poles, each of which is electrically connected to one of the electrode poles 201, 202, 203, and 204.

[0074] When comparing the embodiment of Figure 2 with the prior art shown in Figure 1A, it is obvious that the implantation of the CRT-D electrode 20 is much easier than an implantation of the right ventricular stimulation and shock electrode 8, the right atrial stimulation and sensing electrode 9, and the left ventricular stimulation and sensing electrode 10 of the prior art CRT-D system 6. Instead of having to implant three different electrodes, only a single electrode, namely the CRT-D electrode 20, needs to be implanted. In case the CRT-D electrode 20 comprises only a single connector, a header of a corresponding stimulation generator can also be designed in a much smaller way (confer Figure 6 for more details).

[0075] Due to an implantation of the first electrode pole 201 within the deep septum 13 of the human heart 1, it is possible to achieve an effective stimulation of the left ventricle 5 by stimulating the left bundle branch. This procedure is also known as left bundle branch area pacing (LBBAP). Such LBBAP is also possible in case of a left bundle branch block, as long as the first electrode pole 201 is implanted distally of the left bundle branch block so that it can stimulate the non-blocked sections of the left bundle branch.

[0076] The second electrode pole 202 serves as counter electrode for the first electrode pole 201 in case of sensing of heart signals and a stimulation of the heart 1 by the first electrode pole 201. If a shock pulse is delivered by the second electrode pole 202, a housing of the stimulation generator (not shown in Figure 2) serves as counter electrode for the second electrode pole 202.

[0077] Figure 3A shows a human heart 1 into which a CRT-P electrode 20 is implanted. The general setup of this CRT-P electrode 20 is very similar to the CRT-D electrode 20 shown in Figure 2. However, the second electrode pole 202 of the CRT-P electrode 20 of Figure 3A is not configured as shock coil. Rather, it is arranged and designed as a ring electrode and is implanted together with the first electrode pole 201 within the septum 13 of the heart 1. Here, the first electrode pole 201 and the second electrode pole 202 form a distal dipole 207. Regarding all other elements of the CRT-P electrode 20 and its functionality with respect to a ventricular stimulation, reference is made to the explanations given above with respect to Figure 2 that are also valid for the embodiment shown in Figure 3A.

[0078] The distal dipole 207 can adopt different polarities. This is shown in a schematic detail illustration of a distal section of the CRT-P electrode 20 of Figure 3A in Figure 3B. The helical first electrode pole 201 can serve as cathode. Then, the second electrode pole 202 serves as anode. Likewise, it would also be possible that the first electrode pole 201 serves as anode, in which case the second electrode pole 202 would serve as cathode.

[0079] It is particularly appropriate to operate a CRT-P device comprising the CRT-P electrode 20 of Figure 3A and Figure 3B in a VAT mode, i.e. in a mode employing ventricular stimulation in response to atrial sensing and allowing only triggering.

[0080] Figure 4A shows a human heart 1 into which a CRT-D electrode 20 is implanted that comprises five electrode poles. The first electrode pole 201 and the second electrode pole 202 are implanted - like in case of the embodiment shown in Figure 3 A -into the septum 13 of the heart 1. They form a distal bipole 207. In addition, the third electrode pole 203 and the fourth electrode pole 204 form a proximal bipole 206 located within the right atrium 2 of the heart 1 and arranged for sensing atrial cardiac signals.

[0081] In addition to the embodiment shown in Figure 3A, the CRT-D electrode 20 additionally comprises a fifth electrode pole 205 configured as shock coil. Thus, Figure 4A represents a combination of the embodiments shown in Figure 2 and Figure 3A. Regarding the implantation site, the sensing functionality, and the stimulation functionality of the CRT-D electrode 20 shown in Figure 4A, reference is made to the explanations given above with respect to Figures 2, 3A and 3B that are also valid for the embodiment shown in Figure 4A.

[0082] If the fifth electrode pole 205 is configured as a shock coil, a distance between a distal end of the fifth electrode pole 205 and a proximal end of the first electrode pole 201 may lie in a range from 10 mm to 30 mm, in particular from 10 mm to 15 mm. Preferably the distance between a distal end of the fifth electrode pole 205 and a proximal end of the first electrode pole 201 is 13 mm. The length of the fifth electrode pole 205 or shock coil along the electrode 20 may lie in the range from 40 mm to 70 mm, in particular from 45 mm to 55 mm.

[0083] Since the CRT-D electrode 20 of Figure 4A comprises five electrode poles, a single connector connecting the electrode lead 20 to a stimulation generator needs to comprise five independent connector poles (one for each electrode pole). An exemplary embodiment of such a connector 208 is shown in Figure 4B in a state in which the connector 208 is inserted into a header port 14 of an implantable medical device.

[0084] The connector 208 comprises a tip connector pole 209 that is electrically connected to the first electrode pole 201. The connector 208 furthermore comprises a first connector ring electrode 210, a second connector ring electrode 211, and a third connector ring electrode 212. These three connector ring electrodes 210, 211, 212 are arranged one after the other proximally of the tip connector pole 209. They have the same diameter and stay in electric contact of the header port 14. The first connector ring electrode 210 is electrically connected with the second electrode pole 202, wherein the second connector ring electrode 211 is connected with the third electrode pole 203, and the third connector ring electrode 212 is electrically connected with the fourth electrode pole 204.

[0085] The connector 208 furthermore comprises a fourth connector ring electrode 213 that is located distally of the third connector ring electrode 212. The fourth connector ring electrode 213 has a bigger diameter than the three other connector ring electrodes 210, 211, and 212. The header port 14 also has a wider connector receiving portion in the area of the fourth connector ring electrode 213. If a standard four- pole connector is inserted into the header port 14, the fifth electrical contact of the connector port 14 will simply not have a counterpart to be contacted in the inserted electrode. However, the header port 14 would generally allow such insertion of a four-pole connector and is thus downwards compatible.

[0086] In an alternative embodiment of the CRT-D electrode 20, the third and fourth electrode poles 203 and 204 may be replaced by a second, proximal shock coil. In this case the electrode 20 may be connected to the stimulation generator by four-pole electrode connector, for example a DF4-standard connector, to the five-pole connector port 14. In this case, the second, proximal shock coil is connected with the third ring connector pole 212, while the fourth ring connector pole 213 remains idle.

[0087] If the connector 208 is placed within the header port 14, the tip connector pole 209 is contacted by a grub screw 140 of the header port 14 to establish an electric contact to the remaining portions of the stimulation unit of the implantable medical device. The different connector ring electrodes 210, 211, 212, and 213 are each connected by an individual ring spring 141 to establish such electric contact with the remaining portions of the stimulation unit of the implantable medical device.

[0088] Insulation elements 214 are located between the tip connector pole 209 and the first connector ring electrode 210 as well as between all other connector ring electrodes 210, 211, 212, and 213.

[0089] Figure 5 shows a prior art two-chamber pulse generator system 16 comprising a stimulation generator 17 having a header 170 with two header ports 171 and 172. The stimulation generator 17 is provided with these two header ports 171 and 172 since it is often operated with two distinct electrodes, one for the right ventricle 3 and one for the left ventricle 5 of the heart 1. In the prior art setup of Figure 5, the functionalities of these two electrodes are combined within a single VDD electrode 18. To be able to connect the VDD electrode 18 to the stimulation generator 17, it comprises a switch 180 that splits up the electrode lead to a first connector 181 and a second connector 182. The first connector 181 is intended to be inserted into the first header port 171, and the second connector 182 is intended to be inserted into the second header port 172.

[0090] The VDD electrode 18 comprises a helical tip electrode pole 183 fixed within the cardiac tissue of the apex 11 of the heart 1. It furthermore comprises a ring electrode pole 184 proximally arranged of the tip electrode pole 183. The ring electrode pole 184 serves as counter electrode for the tip electrode pole 183 and thus allows bipolar sensing and stimulation. Two further ring electrode poles 185 serve as proximal dipole for sensing atrial signals of the right atrium 2 of the heart 1.

[0091] The implantation of this two-chamber system 16 is easier than that of a classical two-chamber system employing two separate electrodes. Figure 6 shows an embodiment of a novel VDD electrode 20 that only comprises a single connector 208 having four different connector poles 209, 210, 211, and 212. This VDD electrode 20 does not require a switch so that it is much easier implantable than the prior art electrode 18 shown in Figure 5. The electrode poles of the VDD electrode 20 do not differ from the electrode poles of the prior art the electrode 18 shown in Figure 5. Also here, a first electrode pole 201 configured as helical fixing electrode pole, a second electrode pole 202 configured as ring electrode pole, a third electrode pole 203 and a fourth electrode pole 204, both configured as ring electrodes, are featured. In this context, the third electrode pole 203 and the fourth electrode pole 204 form a proximal bipole which is located, in the implanted state of the VDD electrode 20, in the right atrium 2 of the human heart 1.

[0092] Since the VDD electrode 20 only comprises a single connector 208, a header 300 of a stimulation generator 30 can be designed significantly smaller than the header 170 of the prior art stimulation generator 17 shown in Figure 5. The header 300 comprises only a single header port 301 intended to receive the connector 208 of the VDD electrode 20. Due to the presence of only a single header port 301, the connector 208 cannot be inadvertently inserted into a wrong connector port. This additionally facilitates the implantation procedure. Furthermore, the stimulation generator 30 with the small header 300 requires only significant less space than the prior art stimulation generator 17 shown in Figure 5. Consequently, only a small pocket needs to be formed in the patient’s body upon implanting the stimulation generator 30 and the VDD electrode 20.

[0093] Figure 7 shows a human heart 1 into which another CRT-D electrode 20 is implanted that comprises five electrode poles similar as in Figure 4A. In contrast to the electrode 20 of Figure 4A the electrode 20 comprises a first connector 181 and a second connector 208 that are connected to the electrode poles (204, 203, 205, 202, 207) via a switch 200. The first connector 181 is constructed, for instance, according to the IS1 standard and the second connector 208 is constructed, for instance, according to the DF4 standard. Via the switch 200 the third and fourth electrode poles (203, 204) are connected with the first connector 181 and the first, second and fifth electrodes (201, 202, 205) are connected with the second connector 208. The electrode 20 is connectable with a CRT-D stimulation device 30. The stimulation device 30 comprises a header 300 with a first receiving socket 302 and a second receiving socket 301. The first receiving socket 302 is compatible with the IS1 standard and adapted to receive the first connector 181. The second receiving socket 301 is compatible with the DF4 standard and adapted to receive the second connector 208.

[0094] Since the second connector 208 is constructed according to the DF4 standard, the second connector 208 has four connector poles. Thus, in this embodiment with an IS1 connector and a DF4 connector, one connector pole remains idle. However, the advantage of an electrode according the embodiment of Figure 7 is that the proximal third and fourth electrode poles 203, 204 can be replaced by implanting and connecting a second electrode after disconnecting and removing the first connector 181 without the necessity to explant the electrode 20. In this way the pure sensing electrode poles 203 and 204 can be replaced by an electrode with atrial stimulation ability comparatively easy if necessary.

Claims

Claims1. Electrode (20) for an implantable medical device for stimulating a human or animal heart, characterized in that the electrode (20) comprises at least four electrode poles (201, 202, 203, 204, 205) and a connector (208) comprising at least four connector poles (209, 210, 211, 212, 213), wherein at least three of the four electrode poles (201, 202, 203, 204, 205) are each associated with one of the four connector poles, and wherein the electrode does not comprise more than two connectors.

2. Electrode according to the preceding claim, characterized by a single connector, wherein each of the at least four connector poles of the single connector is associated with one of the at least four electrode poles.

3. Electrode according to claim 1, characterized in that a first electrode pole (201) of the at least four electrode poles (201, 202, 203, 204, 205) is a helix electrode pole or a fixation anchor electrode pole that is designed and configured to be secured within cardiac tissue (11, 13), or the first electrode pole (201) of the at least four electrode poles (201, 202, 203, 204, 205) is a distal electrode pole and the electrode (20) comprises a fixing element that is designed and configured to be secured within cardiac issue (11, 13), wherein the fixing element is electrically insulated from the first electrode pole (201).

4. Electrode according to claim 3, characterized in that a second electrode pole (202) of the at least four electrode poles (201, 202, 203, 204, 205) is one of a ring electrode pole and a shock coil, wherein the second electrode pole (202) is located proximally from the first electrode pole (201).

5. Electrode according to claim 4, characterized in that the second electrode pole (202) is a shock coil, wherein the shock coil has a surface of at least 150 mm2.

6. Electrode according to claims 4 or 5, characterized in that a distance between a distal end of the second electrode pole (202) and a proximal end of the first electrode pole (201) is at least 10 mm.

7. Electrode according to any of claims 3 to 6, characterized in that a third electrode pole (203) and a fourth electrode pole (204) of the at least four electrode poles (201, 202, 203, 204, 205) are ring electrode poles, wherein the third electrode pole (203) and fourth electrode pole (204) are designed and configured such that one of the third and fourth electrode poles (203, 204)serves as counter electrode pole for the respective other electrode pole (204, 203), wherein the third electrode pole (203) is located proximally from the second electrode pole (202) and wherein the fourth electrode pole (204) is located proximally from the third electrode pole (203).

8. Electrode according to any of the preceding claims, characterized in that the electrode (20) comprises at least five electrode poles (201, 202, 203, 204, 205).

9. Electrode according to claim 8, characterized in that a second electrode pole (202) of the at least five electrode poles (201, 202, 203, 204, 205) is a ring electrode pole and in that a fifth electrode pole (205) of the at least five electrode poles (201, 202, 203, 204, 205) is a shock coil, wherein the fifth electrode pole (205) is located proximally from the second electrode pole (202).

10. Electrode according to any of the preceding claims, characterized in that the electrode (20) comprises a drug -eluting reservoir in a distal region of the electrode (20).

11. Implantable medical device for stimulating a human or animal heart, comprising a stimulation unit configured to stimulate a human or animal heart, and a detection unit configured to detect an electric signal of the same heart, characterized in that the implantable medical device comprises an electrode (20) according to any of the preceding claims as only electrode, wherein the electrode (20) forms part of the stimulation unit and of the detection unit.

12. Implantable medical device according to claim 11, characterized in that the implantable medical device is a device for cardiac re synchronization therapy and defibrillation, a device for cardiac re synchronization therapy and pacing, or an implantable pulse generator for an anti- brady cardie therapy.

13. Implantable medical device according to claim 11 or 12, characterized in that the implantable medical device comprises a header (300) having only a single electrode connector receiving socket (301) and / or five-pole electrode connector receiving socket wherein a first inner diameter of the electrode connector receiving socket in an area of an outermost socket pole is larger than a second inner diameter in an area of an adjacent socket pole.

14. Implantable medical device according to any of claims 11 to 13, characterized in that the electrode (20) comprises a first electrode pole (201), a second electrode pole (202), a third electrode pole (203), and a fourth electrode pole (204), and in that the implantable medical device further comprises a processor and a memory unit, wherein the memory unit comprises a- 1 - computer-readable program that causes the processor to perform the following steps when being executed on the processor: a) sensing, with the third electrode pole (203) and the fourth electrode pole (204), atrial cardiac signals; b) providing an anti-tachycardic therapy by emitting an electric pulse by the first electrode pole (201) and / or the second electrode pole (202); and / or providing a cardiac re synchronization therapy by emitting an electric pulse by the first electrode pole (201) and / or the second electrode pole (202); and / or providing an anti-bradycardic therapy by emitting an electric pulse by the first electrode pole (201) and / or the second electrode pole (202).

15. Method of implanting an implantable medical device according to any of claims 11 to 14 in a patient in need thereof, the method comprising the following steps: a) guiding the electrode (20) of the implantable medical device into the right ventricle (3) of the patient’s heart (1); b) fixing a distal tip (201) of the electrode (20) in the septum (13) of the patient’s heart (1) or in the apex (11) of the patient’s heart (1) such that a first electrode pole (201) is located within the septum (13) or the apex (11), respectively, a second electrode pole (202) is i) is also located within the septum (13) or the apex (11), respectively, or ii) is located within the right ventricle (3), and a third electrode pole (203) as well as a fourth electrode pole (204) are located in the right atrium (2) of the patient’s heart (1); c) connecting the electrode (20) with the connector (208) to a header (300) of a housing (30) of the implantable medical device; and d) implanting the housing (30) at an appropriate site outside the patient’s heart (1) within the patient’s body.

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