Implantable medical device for stimulating a human or animal heart enabling retrofitting of an additional electrode

Abstract

The invention relates to an implantable medical device for stimulating a human or animal heart, comprising a stimulation unit (316) configured to generate stimulation pulses to be applied to a human or animal heart (1), a detection unit (311) configured to detect an electric signal of the same heart (1), and a first electrode connector receiving socket (301) for receiving a first electrode (20) having at least two proximal electrode poles (203, 204), a first distal electrode pole (201, 202) and a first single connector (208) comprising an individual connector pole (209, 210, 211, 212) for each electrode pole (201, 202, 203, 204) of the first electrode, a second electrode connector receiving socket (302) for receiving a second electrode (25) having at least two electrode poles (251, 252) and a second single connector (260) comprising an individual connector pole for each electrode pole of the second electrode (25), and a switching device (314) for electrically connecting either the proximal electrode poles (203, 204) of the first electrode (20) or the at least two electrode poles (251, 252) of the second electrode (25) with the detection unit (311) and / or the stimulation unit (316).

Description

[0001] Applicant: BIOTRONIK SE & Co. KG

[0002] Date: 09.12.2025

[0003] Our Reference: 23.173P-WO

[0004] Implantable medical device for stimulating a human or animal heart enabling retrofitting of an additional electrode

[0005] The present invention relates to an implantable medical device according to the preamble of claim 1 and to a method of activating and deactivating electrode poles of an implantable medical device according to the preamble of claim 15.

[0006] 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 resynchronization therapy and a defibrillation of the patient’s heart. Most CRT-D devices typically have 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. In addition, solutions have been described that require only a single electrode that integrates all ventricular and atrial sensing and stimulation functionalities.

[0007] If the implantable medical device is designed and arranged as a CRT-P device, i.e., a device for cardiac resynchronization 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.

[0008] As outlined above, prior art already teaches a specific variant of integrated electrodes that use 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. For such a setup, solutions are known that have only a single electrode connector and a singleelectrode connector receiving socket so that the header of a pulse generator of an according implantable medical device is particularly small. However, such a solution does not enable retrofitting of an additional atrial electrode if an atrial stimulation is required or if the atrial sensing provided with the proximal bipole of the ventricular electrode is no longer sufficiently sensitive. However, the possibility of such retrofitting of an additional atrial electrode appears to be a market demand.

[0009] It is an object of the present invention to provide an implantable medical device for stimulating a human or animal heart that is configured to be used as single lead cardiac stimulation device but enables retrofitting of an atrial electrode.

[0010] This object is achieved with an implantable medical device for stimulating a human or animal heart having the features of claim 1.

[0011] Such a device comprises a stimulation unit configured to generate stimulation pulses to be applied to a human or animal heart. It further comprises a detection unit configured to detect an electric signal of the same heart. Additionally, the implantable medical device comprises a first electrode connector receiving socket for receiving a first electrode having at least two proximal electrode poles and a first distal electrode pole and a first single connector comprising an individual connector pole for each electrode pole of the first electrode. This single connector is connectable to the implantable medical device by way of the first electrode connector receiving socket that allows introducing the single connector for establishing an electrical contact between the detection unit and / or the stimulation unit on the one hand and the individual connector poles and thus each electrode poles of the first electrode on the other hand.

[0012] According to an aspect of the present invention, the implantable medical device comprises a second electrode connector receiving socket for receiving a second electrode. The second electrode, which initially does not form part of the implantable medical device but is rather intended to be retrofitted to the implantable medical device, comprises at least two electrode poles, in particular exactly two, three, or four electrode poles. Embodiments featuring exactly two electrode poles are particularly appropriate since the second electrode is

[0013] 23.173P-WO / 09.12.2025intended to be used as atrial electrode typically requiring exactly two electrode poles. Likewise, the second electrode connector receiving socket comprises at least two electrode pole connectors, in particular exactly two, three or four electrode pole connectors (the number of electrode pole connectors of the second electrode connector receiving socket typically resembles the number of electrode poles of the second electrode to be connected with the electrode connector receiving socket). In addition, the implantable medical device comprises a switching device. The switching device is arranged and configured for electrically connecting either the two proximal electrode poles of the first electrode (in particular those two proximal electrode poles of the first electrode that form an atrial bipole such as a floating bipole within the (right) atrium of the patient’s heart) or the at least two electrode poles of the second electrode with the detection unit and / or stimulation unit. Thus, the switching device serves for establishing an electric connection, in particular an operative electrical connection, between the detection unit and / or the stimulation unit on the one hand and either the two proximal electrode poles of the first electrode or - if a second electrode is connected with the second electrode connector receiving socket - with the electrode poles of the second electrode.

[0014] The switching device makes it possible that an atrial electrode, e.g. an atrial electrode that is to be screwed into atrial tissue, can be retrofitted to the implantable medical device and can replace the originally present atrial electrode poles of the first electrode, such as floating atrial electrode poles.

[0015] Thus, the implantable medical device with the second electrode connector receiving socket and the switching device enables to retrofit a single-lead cardiac stimulation device such as a single-lead conduction system pacing device with a screwed atrial electrode in a particularly simple manner. This increases the market acceptance of such single-lead devices significantly since the presently claimed and described device features a particularly simple implantation and still enables a long lifetime due to the possibility of retrofitting a “classic” atrial electrode.

[0016] In an embodiment, the implantable medical device includes the first electrode as a component so that the first electrode is part of the implantable medical device.

[0017] 23.173P-WO / 09.12.2025In an embodiment, the first distal electrode pole of the first electrode is a helical electrode pole (also referred to as 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. In an embodiment, the cardiac tissue into which the helix electrode pole is to be secured is the apex. In another embodiment, the cardiac tissue into which the helix electrode pole is to be secured is the septum. After having implanted the first distal 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 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.

[0018] 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.

[0019] In an embodiment, the first 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 distal electrode pole. The fixing element is, in an embodiment, designed as fixing helix. By securing the fixing element into the cardiac tissue it is possible to stimulate the patient’s cardiac tissue with the first distal electrode pole in a similar way as explained above with respect to the embodiments in which the first distal electrode pole is designed as helix electrode pole. Thus, also in case of a first distal electrode pole and a separate fixing element, it is possible to use the first distal electrode pole for LBBAP. Consequently, also the first distal 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.

[0020] 23.173P-WO / 09.12.2025In an embodiment, the first electrode comprises a second distal electrode pole which is a ring electrode or a shock coil. In this context, the second distal electrode pole is located proximally of the first distal electrode pole. If the second distal electrode pole is designed as shock coil, it is particularly appropriate that the implantable medical device is 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 implantable medical device shall not be designed as a CRT-D device, but rather as a CRT-P device, the second distal 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 distal electrode pole as ring electrode pole enables an implantation of the first distal electrode pole and the second distal electrode pole within cardiac tissue, in particular within the apex or 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 distal electrode pole against the housing of the implantable medical device) or in a bipolar manner (the first distal electrode pole against the second distal electrode pole). In such a set-up, the first distal electrode pole (optionally designed as helix electrode pole) is typically used as cathode, wherein the second distal electrode pole or ring electrode pole is typically used as counter electrode. The factual stimulation site will then be the first distal electrode pole which is, in the implanted state of the electrode, even closer positioned to the left ventricle and can thus effectuate even a left ventricular stimulation in a very appropriate way, in particular as LBBAP.

[0021] In an embodiment, the second distal 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, in particular surface lying in a range from 150 mm2to 250 mm2, in particular from 175 mm2to 225 mm2, in particular from 200 mm2to 225 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.

[0022] In an embodiment, a distance between a distal end of the second distal electrode pole and a proximal end of the first distal 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

[0023] 23.173P-WO / 09.12.2025second distal electrode pole and the proximal end of the first distal electrode pole lies in a range of 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 distal electrode pole and the second distal electrode pole is particularly appropriate if the second distal electrode pole is designed as shock coil. In contrast, if the second distal electrode pole is designed as ring electrode pole and is intended to form together with the first distal 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 distal electrode pole and the second distal electrode pole is also conceivable.

[0024] In an embodiment, the two proximal electrode poles are ring electrode poles. In this context, the the two proximal electrode poles are designed and configured such that one of the two proximal electrode poles serves as counter electrode pole for the respective other electrode pole. In addition, a first proximal electrode pole of the two proximal electrode poles is located proximally from the second distal electrode pole, and a second proximal electrode pole of the two proximal electrode poles is located proximally from the first proximal electrode pole. Expressed in other words, the first proximal electrode pole and the second proximal electrode pole form a bipolar electrode pole arrangement that is located proximally of the second distal electrode pole. By such an arrangement, it is possible that the first proximal electrode pole and the second proximal electrode pole are located, in an implanted state of the first electrode, in the right atrium of the patient’s heart. Then, the first proximal electrode pole and the second proximal 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 distal electrode pole and / or the second distal 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. However, the implantable medical device still enables the retrofitting of an additional atrial electrode in case that atrial sensing with the first and second proximal electrode poles of the first

[0025] 23.173P-WO / 09.12.2025electrode is considered to be no longer sufficient. Since the first and second proximal electrode poles are intended to be used in the atrium of the patient’s heart, they can also be referred to as proximal electrode poles or atrial electrode poles, respectively.

[0026] If the first electrode is designed as a VDD electrode, it also enables a VAT operation, i.e., a ventricular stimulation after 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. A VAT operation is also possible if the second electrode has been connected to the detection unit and / or stimulation unit of the implantable medical device and thus forms part of the implantable medical device. Then, atrial signals sensed with the second electrode can be used as input signals for ventricular stimulation signals to be omitted by the first electrode.

[0027] Since the first electrode is a switch-free electrode and since 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 first 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. However, even though these advantageous properties of the implantable medical device regarding its implantation procedure are kept, the implantable medical device enables a retrofitting of an additional atrial electrode due to the switching device present in the implantable medical device.

[0028] Due to its small dimensions, the first electrode is 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

[0029] 23.173P-WO / 09.12.2025first 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. 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.

[0030] In an embodiment, the electrode lead of the first electrode (and / or the second electrode, if forming part of the implantable medical device) has a diameter of 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.

[0031] In an embodiment, the connector of the first 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 distal electrode pole is configured as shock coil.

[0032] In an embodiment, the connector of the first 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 distal electrode pole is designed as ring electrode pole.

[0033] In an embodiment, the first 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 apex or septum and a defibrillation electrode pole 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 distal 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 distal electrode pole, but

[0034] 23.173P-WO / 09.12.2025distally of the first proximal electrode pole, i.e., between the second distal and the first proximal electrode pole.

[0035] 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.

[0036] In an embodiment, the pin connector pole (first connector pole or innermost connector pole) is electrically connected with the tip electrode pole (first distal 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 distal 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.

[0037] 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.

[0038] The fourth connector pole (third connector ring pole) is electrically connected to one of the first and second proximal electrode poles. The fifth connector pole (fourth connector ring pole) is electrically connected to the respective other of the first and second proximal

[0039] 23.173P-WO / 09.12.2025electrode poles. As explained above, the first and second proximal 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.

[0040] In an embodiment, the connector of the first electrode comprises a first connector pole designed as non-pin 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.

[0041] In an embodiment, the first electrode (and / or the second electrode, if forming part of the implantable medical device) comprises a drug-eluting reservoir in a distal region of the respective electrode. The distal region of the respective electrode typically comprises the distal third of the overall length of the respective 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 respective 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 drug-eluting reservoir is refillable. This facilitates an explantation and novel implantation of the respective electrode.

[0042] In an embodiment, the switching device is configured to automatically switch from a first configuration to a second configuration upon recognizing that the second electrode is received within the second electrode connector receiving socket. In the first configuration,

[0043] 23.173P-WO / 09.12.2025an electric connection between the two proximal electrode poles of the first electrode on the one hand and the detection unit and / or the stimulation unit on the other hand is established. In the second configuration, an electric connection between the at least two electrode poles of the second electrode on the one hand and the detection unit and / or the stimulation unit on the other hand is established. Thus, the second configuration enables an electric connection between the electrode poles of the second electrode and the detection unit and / or the stimulation unit of the implantable medical device.

[0044] In an embodiment, the switching device is configured to automatically switch back from the second configuration to the first configuration upon recognizing that the second electrode is no longer received within the second electrode connector receiving socket. Since such a switchback from the second configuration to the first configuration is not expected to occur likely (if the second electrode has been implanted to the patient, it will remain within the patient’s body), a switchback from the second configuration to the first configuration is disabled in an embodiment. Thus, in that embodiment, the switching device is only able to switch from the first configuration to the second configuration.

[0045] In an embodiment, the implantable medical device is designed and configured to recognize the presence of the second electrode in the second electrode connector receiving socket by an impedance measurement. This can be done by emitting low-energy pulses and sensing response signals.

[0046] In an embodiment, the implantable medical device is configured, if the two proximal electrode poles of the first electrode are connected with the stimulation unit and / or the detection unit, such that the two proximal electrode poles of the first electrode can only be used for sensing cardiac electric signals but not for emitting stimulation pulses. Thus, this configuration has the same result as connecting the two proximal electrode poles of the first electrode with the detection unit only. However, they can be generally electrically connected with the stimulation unit, as far as the respective channels cannot be used for transmitting stimulation pulses from the stimulation unit to the two proximal electrode poles. In an embodiment, the sensing with the two proximal electrode poles is enabled with increased

[0047] 23.173P-WO / 09.12.2025sensitivity or with sensing parameters specifically adapted to sensing atrial signals with a (floating) atrial bipole, respectively.

[0048] In an embodiment, the implantable medical device is configured, if the at least two electrode pole connectors of the second electrode connector receiving socket are connected with the detection unit and optionally with the stimulation unit, such that the at least two electrode poles of the second electrode received within the second electrode connector receiving socket can be used for sensing cardiac electric signals and optionally also for emitting stimulation pulses. Thus, the second electrode can be used for atrial sensing and atrial stimulation in this embodiment. As explained above, the second electrode can be an electrode that is to be screwed into cardiac tissue so that the stimulation with the second electrode can be realized much more efficiently than in case of using a floating atrial bipole like in case of the first electrode. Therefore, the first electrode is mainly intended for sensing atrial signals, whereas the second electrode features both sensing and stimulation functionalities in the atrium of the patient’s heart.

[0049] In an embodiment, the implantable medical device is a device for cardiac resynchronization therapy and defibrillation (CRT-D device), a device for cardiac resynchronization therapy and pacing (CRT-P device), an implantable cardioverter-defibrillator (ICD), or an implantable pulse generator (IPG) for an anti-bradycardic therapy. All these devices will take significant advantage of the presently described switching device due to the abovedescribed properties and features made possible by the switching device.

[0050] In an embodiment, the implantable medical device 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.

[0051] First, it is determined whether a second electrode comprising at least two electrode poles is received within the second electrode connector receiving socket of the pulse generator of the implantable medical device.

[0052] 23.173P-WO / 09.12.2025If a second electrode is received within the second electrode connector receiving socket, the switching device is caused to switch an electric connection from a first configuration to a second configuration. In the first configuration, an electric connection is established between the two proximal electrode poles of the first electrode on the one hand and the stimulation unit and / or the detection unit on the other hand. In the second configuration, an electric connection is established between the at least two electrode poles of the second electrode on the one hand and the stimulation unit and / or the detection unit on the other hand. Thus, in the second configuration, the at least two electrode poles of the second electrode are - via the at least two electrode pole connectors of the second electrode connector receiving socket - electrically connected with the stimulation unit and / or the detection unit.

[0053] In an aspect, the present invention relates to a method of activating or deactivating electrode poles of an implantable medical device, in particular of an implantable medical device according to the preceding explanations. The method comprises the steps explained in the following.

[0054] First, a medical device for stimulating a human or animal heart is provided. This device comprises a stimulation unit configured to generate stimulation pulses to be applied to a human or animal heart. It further comprises a detection unit configured to detect an electric signal of the same heart. Optionally, the implantable medical device comprises a first electrode that may form part of the stimulation unit and of the detection unit. The first electrode comprises at least two proximal electrode poles and a distal electrode pole. The first electrode further comprises an individual connector pole for each electrode pole. These individual connector poles are arranged on a first single connector. This first single connector is connected to a housing of the implantable medical device with the help of a first electrode connector receiving socket that allows introducing the first single connector and establishing an electrical contact between the detection unit and / or the stimulation unit on the one hand and the individual connector poles and thus each electrode pole on the other hand. The implantable medical device furthermore comprises a second electrode connector receiving socket for receiving a second electrode. The second electrode, which initially does not form part of the implantable medical device but is rather intended to be retrofitted to the implantable medical device, comprises at least two electrode poles, in particular exactly two,

[0055] 23.173P-WO / 09.12.2025three, or four electrode poles. Embodiments featuring exactly two electrode poles are particularly appropriate since the second electrode is intended to be used as atrial electrode typically requiring exactly two electrode poles. The second electrode comprises a second single connector comprising an individual connector pole for each electrode pole (the number of individual connector poles of the second single connector typically resembles the number of electrode poles of the second electrode to be connected with the electrode connector receiving socket). In addition, the implantable medical device comprises a switching device. The switching device is arranged and configured for electrically connecting either two proximal electrode poles of the first electrode (in particular those two proximal electrode poles of the first electrode that form an atrial bipole such as a floating bipole within the (right) atrium of the patient’s heart) or the at least two electrode poles of the second electrode via the second connector receiving socket with the stimulation unit and / or the detection unit. Thus, the switching device serves for establishing an electric connection between the detection unit and / or the stimulation unit on the one hand and either the two proximal electrode poles of the first electrode or - if a second electrode is connected with the second electrode connector receiving socket - the electrode poles of the second electrode.

[0056] Afterwards, it is determined whether a second electrode comprising at least two electrode poles is received within the second electrode connector receiving socket of the housing of the implantable medical device.

[0057] If the second electrode is received within the second electrode connector receiving socket, the switching device is caused to switch an electric connection from a first configuration to a second configuration. In the first configuration, an electric connection is established between the two proximal electrode poles of the first electrode on the one hand and the stimulation unit and / or the detection unit on the other hand. In the second configuration, an electric connection is established between the at least two electrode poles of the second electrode on the one hand and the stimulation unit and / or the detection unit on the other hand. Thus, in the second configuration, the at least two electrode poles of the second electrode are - via the at least two electrode pole connectors of the second electrode connector receiving socket - electrically connected with the stimulation unit and / or the detection unit.

[0058] 23.173P-WO / 09.12.2025All 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 method. Likewise, 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 implantable medical device.

[0059] 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:

[0060] Figure 1 shows an embodiment of a single-lead conduction system pacing device and a four-pole electrode implanted into a human heart;

[0061] Figure 2 shows an embodiment of the single-lead conduction system pacing device of Figure 1 retrofitted with an additional atrial electrode;

[0062] Figure 3 schematically shows different components of the single-lead conduction system pacing device of Figure 1; and

[0063] Figure 4 shows a schematic diagram of an embodiment of the switching device of the single lead conduction system pacing device of Figure 1.

[0064] Figure 1 shows an implantable medical device 15 comprising a pulse generator 30 and a first electrode 20 that is to be connected to the pulse generator 30. The first electrode 20 may be a separate part used together with the implantable medical device 15 or may be an integrated component of the implantable medical device 15. The first electrode 20 is a four-pole electrode 20 and is shown in its implanted state in which it is implanted into a human heart 1. This first electrode 20 is guided through the superior 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 first electrode 20, a first electrode pole 201 of the first electrode 20 is designed as helical electrode pole. It is screwed into the septum 13 so that it almost reaches the left ventricle 5

[0065] 23.173P-WO / 09.12.2025(but still stays within the septum 13). In other embodiments not shown in the figures, the first electrode 20 is secured within the apex of the heart 1.

[0066] The first electrode 20 further comprises a second electrode pole 202 that is designed as ring electrode pole and that is located, in the implanted state of the first electrode 20, also within the septum 13.

[0067] The first 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 (in case that no corresponding ventricular signals have been detected).

[0068] The first electrode 20 comprises only a single electrode connector 208 that has four connector poles 209, 210, 211, 212, each of which is electrically connected to one of the electrode poles 201, 202, 203, and 204.

[0069] The single electrode connector 208 is intended to be inserted into the first electrode connector receiving socket 301 that is arranged on a header 303 of the pulse generator 30. The header 303 forms part of a housing 300 of the pulse generator 30.

[0070] 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.

[0071] 23.173P-WO / 09.12.2025The second electrode pole 202 serves as counter electrode for the first electrode pole 201 in case of a stimulation of the heart 1 by the first electrode pole 201.

[0072] The header 303 also comprises a second electrode connector receiving socket 302 that is intended to be connected with an atrial electrode that can be retrofitted to the implantable medical device 15.

[0073] The retrofitting is shown in more detail in Figure 2. Here, a second electrode 25 serving as atrial electrode has been implanted into the right atrium 2 of the patient’s heart 1. For this purpose, the second electrode 25 is also guided through the superior vena cava 12 into the patient’s heart 1. The second electrode 25 serves for replacing the proximal bipole 206 of the first electrode 20 in case that an atrial stimulation is desired or in case that sensing of atrial signals with the proximal bipole 206 is no longer as efficient as desired.

[0074] For achieving good conduction of stimulation signals, the second electrode 25 is screwed into atrial tissue in the region of the septum 13. A first atrial electrode pole 251 is secured within atrial tissue, wherein a second atrial electrode pole 252 is located close to the septum 13 and serves as counter electrode for the first atrial electrode pole 251.

[0075] The second electrode 25 comprises a second electrode connector 258 that is intended to be inserted into the second electrode connector receiving socket 302 arranged on the header 303 of the pulse generator 30. The second electrode connector 258 comprises two connector poles 259, 260 that establish an electric contact between two electrode pole connectors 3021 of the second electrode connector receiving socket 302 on the one hand and the first atrial electrode pole 251 as well as the second atrial electrode pole 252 on the other hand.

[0076] Amongst other units (confer Figure 3 in this respect for more detail), the pulse generator 30 comprises a switching unit 314 that serves for switching an electric contact between the pulse generator 30 on the one hand and i) the proximal bipole 206 of the first electrode 20 or ii) the first atrial electrode pole 251 and the second electrode pole 252 of the second electrode 25 on the other hand. Thus, the switching device 314 establishes, in a first configuration, an electric contact between those two of the connector poles 209, 210, 2011, 212 of the first

[0077] 23.173P-WO / 09.12.2025electrode 20 that are in electrical contact with the third electrode pole 203 and the second electrode pole 204 that serve as floating atrial electrode bipole 206. In a second configuration, the switching device 314 establishes an electric contact between the electrode pole connectors 3021 of the second electrode connector receiving socket 302 and the connector poles 259, 260 of the second electrode 25 and thus an electrical contact between the pulse generator 30 and the first and second atrial electrode poles 251, 252. The switching device 314 typically switches from its first configuration to the second configuration upon recognizing the introduction of the second electrode connector 258 into the second electrode connector receiving socket 302. Then, the third electrode pole 203 and the fourth electrode pole 204 of the first electrode 20 are deactivated, whereas the first atrial electrode pole 251 and the second atrial electrode pole 252 of the second electrode 25 are activated.

[0078] Figure 3 schematically illustrates individual components of the implantable medical device 15 shown in Figures 1 and 2 that are comprised within the pulse generator 30 of the implantable medical device 15. The pulse generator 30 houses a detection unit 311 (also referred to as sensing unit) that typically comprises an analog-to-digital converter, a bandpass filter, and an offset compensation. The detection unit 311 is operatively connected with a processor 312 that has access to a memory unit 313. The memory unit 313 serves for storing instructions for the processor 312 as well as data detected by the detection unit 311. The pulse generator 30 also comprises the switching unit 314 that was already explained with respect to Figure 2 and that will be explained in more detail with respect to Figure 4. The pulse generator 30 further optionally comprises an evaluation unit 315 that can also be part of the processor 312 and that serves for extracting features from the detected cardiac electric signal. The pulse generator 30 further comprises a stimulation unit 316 that serves for stimulating the heart from which the detection unit 311 detects electric signals. The first electrode 20 (along with its electrode poles 201, 202, 203, 204; confer Figures 1 and 2) forms part of the detection unit 311 and of the stimulation unit 316. Additionally, the pulse generator 30 optionally comprises a communication unit 317 that serves for data transfer to a (remote) programming device.

[0079] Figure 4 shows a schematic diagram of an embodiment of the switching unit 314 that forms part of the pulse generator 30 as already explained with respect to Figures 2 and 3. The

[0080] 23.173P-WO / 09.12.2025switching unit 314 comprises a first switch SI and a second switch S2. Both switches SI, S2 can only be switched together. In their position illustrated in Figure 4, the switches SI, S2 establish contact between the pulse generator 30 and the third electrode pole 203 and the fourth electrode pole 204 of the first electrode 20, i.e. to the proximal bipole 206 of the first electrode 20 (confer Figures 1 and 2 for more details). If both switches SI, S2 are switched into their second position, an electric connection between the pulse generator 30 and the first atrial electrode pole 251 and the second atrial electrode pole 252 of the second electrode 25 is established. Thus, if the second electrode 25 is connected to the pulse generator 30, the switching device 214 serves for activating the first atrial electrode pole 251 and the second atrial pole 252 and to deactivate at the same time the third electrode pole 203 and the fourth electrode pole 204 of the first electrode 20. The switching device 314 does not influence an electric connection between the pulse generator 30 and the first electrode pole 201 and the second electrode pole 202 of the first electrode 20. These ventricular electrode poles remain in electric connection with the pulse generator 30 throughout the operation of the pulse generator 30.

[0081] Due to the switching device 314 is possible to retrofit the implantable medical device 15 with the second electrode 25 serving as separate atrial electrode and enabling an atrial stimulation as well as a more sensitive atrial sensing than the first four-pole electrode 20 is able to perform.

[0082] 23.173P-WO / 09.12.2025

Claims

Claims1. Implantable medical device for stimulating a human or animal heart, comprising a detection unit (311) configured to detect an electric signal of the heart (1), a stimulation unit (316) configured to generate stimulation pulses to be applied to the heart (1),a first electrode connector receiving socket (301) for receiving a first electrode (20) having at least two proximal electrode poles (203, 204), a first distal electrode pole (201, 202) and a first single connector (208) comprising an individual connector pole (209, 210, 211, 212) for each electrode pole (201, 202, 203, 204) of the first electrode,a second electrode connector receiving socket (302) for receiving a second electrode (25) having at least two electrode poles (251, 252) and a second single connector (260) comprising an individual connector pole for each electrode pole of the second electrode (25), anda switching device (314) for electrically connecting either the proximal electrode poles (203, 204) of the first electrode (20) or the at least two electrode poles (251, 252) of the second electrode (25) with the detection unit (311) and / or the stimulation unit (316).

2. Implantable medical device according to claim 1, characterized by including the first electrode (20) as a component.

3. Implantable medical device according to any of claims 1 or 2, characterized in that the first distal electrode pole (201) of the first electrode (20) is a helix electrode pole that is designed and configured to be secured within cardiac tissue (11, 13).

4. Implantable medical device according to any of claims 1 or 2, characterized in that the first 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 distal electrode pole (201).23.173P-WO / 09.12.20255. Implantable medical device according to any of the preceding claims, characterized in that the first electrode (20) comprises a second distal electrode pole (202) which is one of a ring electrode pole and a shock coil, wherein the second distal electrode pole (202) is located proximally from the first distal electrode pole (201).

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

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

8. Implantable medical device according to any of claims 5 to 7, characterized in that the two proximal electrode poles (203, 204) are ring electrode poles and are designed and configured such that one of the two proximal electrode poles (203, 204) serves as counter electrode pole for the respective other electrode pole (204, 203), wherein a first proximal electrode pole (203) is located proximally from the second distal electrode pole (202) and wherein a second proximal electrode pole (204) is located proximally from the first proximal electrode pole (203).

9. Implantable medical device according to any of the preceding claims, characterized in that the switching device (314) is configured to automatically switch from i) an electric connection between the two proximal electrode poles (203, 204) of the first electrode (20) and the detection unit (311) and / or the stimulation unit (316) to ii) an electric connection between the at least two electrode poles of the second electrode (25) and the detection unit (311) and / or the stimulation unit (316) upon recognizing that the second electrode (25) is received within the second electrode connector receiving socket (302).

10. Implantable medical device according to claim 9, characterized in that the implantable medical device is configured to recognize that the second electrode (25)23.173P-WO / 09.12.2025is received within the second electrode connector receiving socket (302) by an impedance measurement.

11. Implantable medical device according to any of the preceding claims, characterized in that in case that the two proximal electrode poles (203, 204) of the first electrode (20) are electrically connected with the detection unit (311) and / or the stimulation unit (316), the implantable medical device (15) is specifically configured such that the two proximal electrode poles (203, 204) of the first electrode (20) can only be used for sensing cardiac electric signals but not for emitting stimulation pulses.

12. Implantable medical device according to any of the preceding claims, characterized in that in case that the at least two electrode pole connectors (3021) of the second electrode connector receiving socket (302) are electrically connected with the detection unit (311) and optionally with the stimulation unit (316), the implantable medical device (15) is specifically configured such that only the at least two electrode poles (251, 252) of the second electrode (25) received within the second electrode connector receiving socket (302) can be used for sensing cardiac electric signals and optionally also for emitting stimulation pulses.

13. Implantable medical device according to any of the preceding claims, characterized in that the implantable medical device (15) is a device for cardiac resynchronization therapy and defibrillation, a device for cardiac resynchronization therapy and pacing, an implantable cardioverter-defibrillator, or an implantable pulse generator for an anti- brady cardie therapy.

14. Implantable medical device according to any of the preceding claims, characterized in that the implantable medical device (15) comprises a processor (312) and a memory unit (313), wherein the memory unit (313) comprises a computer-readable program that causes the processor (312) to perform the following steps when being executed on the processor (312):23.173P-WO / 09.12.2025a) determining whether the second electrode (25) comprising the at least two electrode poles (251, 252) is received within the second electrode connector receiving socket (302);b) if the second electrode (25) is received within the second electrode connector receiving socket (302), causing the switching device (314) to switch an electric connection between the two proximal electrode poles (203, 204) of the first electrode (20) and the detection unit (311) and / or the stimulation unit (316) to an electric connection between the at least two electrode poles (251, 252) of the second electrode (25) and the detection unit (311) and / or the stimulation unit (316).

15. Method of activating and deactivating electrode poles of an implantable medical device (15) according to any of the preceding claims, the method comprising the following steps:a) determining whether the second electrode (25) comprising the at least two electrode poles (251, 252) is received within the second electrode connector receiving socket (302) of the implantable medical device (15);b) if the second electrode (25) is received within the second electrode connector receiving socket (302), causing a switching device (314) of the implantable medical device (15) to switch an electric connection between the two proximal electrode poles (203, 204) of the first electrode (20) and the detection unit (311) and / or the stimulation unit (316) to an electric connection between the at least two electrode poles (251, 252) of the second electrode (25) with the detection unit (311) and / or the stimulation unit (316).23.173P-WO / 09.12.2025

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