Implantable medical device and method for implanting the implantable medical device

Abstract

An implantable medical device (20) is described. The implantable medical device (20) comprises: a housing (22) having a distal end (28), a proximal end (26), and a through hole (50) extending from the proximal end (26) to the distal end (28); a first electrode (30) being arranged at the housing (22) between the proximal end (26) and the distal end (28) and being exposed to surroundings of the implantable medical device (20); an energy source (48) arranged within the housing (22); an electronic circuit (46) arranged within the housing (22) and electrically coupled to the energy source (48) and the first electrode (30); and an electrode member (32) having at least one second electrode (36) exposed to the surroundings of the implantable medical device (20), with the second electrode (36) being electrically coupled to the electronic circuit (46), wherein the electrode member (32) is at least partly arranged within the through hole (50) of the housing (22) such that it protrudes from the housing (22) at the distal end (28) in distal direction and such that it is arrangeable within the through hole (50) at varying depths (D1, D2), wherein a length over which the electrode member (32) protrudes from the housing (22) at the distal end (28) in distal direction depends on how far the electrode member (32) is arranged within the through hole (50) of the housing (22).

Description

[0001] Applicant: BIOTRONIK SE & Co. KG

[0002] Our Reference: 24.131P-WO

[0003] Date: 08.12.2025

[0004] IMPLANTABLE MEDICAL DEVICE AND METHOD FOR IMPLANTING THE

[0005] IMPLANTABLE MEDICAL DEVICE

[0006] The present invention refers to an implantable medical device, and to a method for implanting the implantable medical device into a body of a human or an animal.

[0007] The Implantable Medical Device (IMD) may be an implantable intracardiac device, such as e.g. an implantable intracardiac pacemaker. Active Intracardiac Medical Devices (AIMD's) or passive intracardiac medical devices, for example implantable intracardiac pacemakers, also known as implantable leadless pacemakers (ILP's), are well known miniaturized medical devices which are entirely implanted into a heart’s chamber or atrium. Intracardiac pacemakers are used for patients who suffer from a bradycardia, that is if a heart that beats too slow to fulfil the physiological needs of the patient. Intracardiac pacemakers apply electrical stimulation in the form of pulses to the heart in order to generate a physiologically appropriate heartrate and / or in the form of shocks for cardioversion or defibrillation in order to restore a more normal heart rhythm. Alternative or additional functions of intracardiac devices comprise providing other electrical or electromagnetic signals to the heart or its surrounding tissue, sensing electrical or electromagnetic signals or other physiological parameters of the heart and / or its surrounding tissue.

[0008] In order to be able to stimulate the heart by electric pulses, the IMD comprises electrodes which come in contact with the body tissue when the IMD is implanted. The electrodes allow AIMD's to treat adjacent tissue by providing an electronic stimulation site and a method of fixation to the target tissue. When developing a leadless AIMD, the fixation means must be attached to the implant and provide secure fixation without slipping or twisting, while providing a reliable contact between the stimulation electrode and the target tissue. It is known to use a tine array comprising several tines as the fixation means. The tine array may be clamped or sticked at a housing of the IMD.

[0009] Conduction system pacing (CSP) is emerging as a form of cardiac resynchronization for patients who are displaying signs of heart failure and reduced ejection fraction. CSP involves placing a transvenous pacing lead, referred to as electrode member in this description, into the septum of the heart of the patient either at the HIS Bundle (HB) or within the Left Bundle Branch (LBB). By targeting the conduction system directly, rather than pacing the myocardium of the ventricle, there is a reduction in activation time and improved synchrony between the right and left ventricles. This is more physiologic for the patient and shows a reduction of adverse clinical outcomes in patients with ventricular pacing requirements of more than 20% in comparison to standard RV pacing (right ventricular pacing).

[0010] Implantable leadless pacemakers (ILP's) have also become an emerging technology that combines the lead and the implant into a single entity for implant directly into the heart. This offers a means for eliminating discomfort experienced by the presence of a large can residing within the patient’s chest while offsetting lead-based mobility restrictions. ILP's also eliminate lead-based transvenous infection pathways to the myocardium and other lead failures that can be present with transvenous pacing. Current ILP technology can only accomplish traditional right ventricle myocardium pacing due to the limitations of the electrode placement and device fixation being only in the myocardium of the right atrium or ventricle.

[0011] Transvenous CSP (LBB or HB pacing) carries the risk of the patient developing an infection along the lead pathway that goes directly into the heart. Transvenous leads also risk mechanical failures such as fractures. The transvenous pacemaker resides in the patient’s chest which can cause physical and / or emotional discomfort and the transvenous leads can limit patient mobility. Additionally, some patients have contraindications for transvenous leads. In addition, transvenous leads tend to become entangled in the tissue or damaged. Further, transvenous leads do not have a 1 : 1 torque translation between a proximal end where the user is rotating and the helix penetrating the septum. This may cause an issue with respect

[0012] 24.131P-WO / 08.12.2025 to torque buildup and unexpected torque breakthrough, making the electrode deployment unpredictable and risking perforations.

[0013] As stated above, ILP's are currently limited to Right Atrial (RA) or Right Ventricular (RV) myocardial pacing and cannot reach the conduction system of the heart to perform CSP. This is due to the limitation of the depth of the pacing electrode, which is controlled by the fixation mechanism on the ILP. Some ILP's are fixed to the heart with tines that hook into the myocardium, wherein the depth at which the lead penetrates the tissue of the patent cannot be controlled by the physician. Other ILP's have a helical fixation means. The helical fixation means has a fixed length which is not long enough to reach the conduction system. Even if the helical fixation means were extended to be long enough to reach the conduction system, it likely would not be stable enough to fix the body of the ILP securely into the septum to provide safe long-term fixation. Since conventional ILP's cannot accomplish CSP, patients who require more than 20% ventricular pacing are at risk for increased left ventricular activation time, reduced ejection fraction, and pacing induced heart failure.

[0014] Accordingly, there is a need for an IMD and a method for implanting the IMD which enable to securely fix the IMD to the tissue of the patient while enabling to accomplish CSP with the IMD, e.g., by enabling to arrange an electrode member of the IMD at varying depth in the tissue in a controllable manner.

[0015] The above problem is solved by the subject matter of the independent claims. Advantageous embodiments are given in the dependent claims.

[0016] An aspect refers to an IMD. The IMD comprises: a housing having a distal end, a proximal end, and a through hole extending from the proximal end to the distal end; a first electrode being arranged at the housing between the proximal end and the distal end and being exposed to surroundings of the implantable medical device; an energy source arranged within the housing; an electronic circuit arranged within the housing and electrically coupled to the energy source and the first electrode; and an electrode member having at least one second electrode exposed to the surroundings of the implantable medical device, with the second electrode being electrically coupled to the electronic circuit, wherein the electrode member

[0017] 24.131P-WO / 08.12.2025 is at least partly arranged within the through hole of the housing such that it protrudes from the housing at the distal end in distal direction and such that it is arrangeable within the through hole at varying depths, wherein a length over which the electrode member protrudes from the housing at the distal end in distal direction depends on how far the electrode member is arranged within the through hole of the housing.

[0018] Another aspect refers to a method for implanting the IMD into a body of a patient. The method comprises: providing the implantable medical device such the electrode member is at least partly arranged within the through hole of the housing such that it protrudes from the housing at the distal end in distal direction; arranging the implantable medical device at the tissue within the body of the patient; and moving the electrode member further within the through hole relative to the housing until the second electrode at the electrode member is arranged at a depth within the tissue as intended for its use.

[0019] The features, advantages and embodiments of the one of the aspects described above and in the following may easily be transferred to features, advantages and embodiments of another one of the aspects.

[0020] The IMD represents a leadless pacemaker (or intracardiac pacemaker) capable of pacing the conduction system of the heart, e.g., HIS bundle or left bundle branch / left bundle branch area. This allows for the benefits of leadless pacing and CSP to be combined. In particular, this will allow patients to have physiological pacing without the discomfort, mobility restrictions, or failure risks of a transvenous pacemaker. The IMD may utilize a tined fixation mechanism having two or more tines which are separate from the pacing electrode, i.e., the second electrode. For example, the implantable medical device may be arranged at the tissue within the body of the patient by the tines. Once the tines are fixated at the tissue, the pacing electrode can be driven into the septum until it reaches the conduction system of any given anatomy. The ability to iteratively drive the pacing electrode into the tissue allows for continual pacing and IEGM (intracardiac electrogram) readings during the deployment of the pacing electrode and electrode member into the tissue. The IMD may be configured for implantation within the ventricle of a heart.

[0021] 24.131P-WO / 08.12.2025 The patient may be a human or an animal. The tissue of the patient may be a tissue of the heart of the patient. The first electrode may act as a return electrode or anode, for example. The second electrode may be a cathode. The second electrode may be referred to as pacing electrode. The second electrode may be extended to provide a means for accessing the conduction system, e.g., HIS bundle or Left bundle branch).

[0022] The electrode member may extend through the through hole of the housing such that at least a tip of the electrode member protrudes from the housing at the distal end of the housing. The electrode member may be electrically insulated against its surroundings, except for the second electrode. The electrode member may be either flexible or rigid. The electrode member may have a length in a range from 3 mm to 30 mm, e.g., from 5 mm to 20 mm. When arranging the IMD in the body such that at least the part of the protruding portion of the electrode member penetrates the tissue of the patient, the electrode member may penetrate the tissue at a depth ranging from 0 mm (excluded) to 20 mm, in particular 0.1 mm to 15 mm, in particular 0.1 mm to 12 mm, in particular 0.1 mm to 10 mm, in particular 0.2 mm to 7 mm, in particular 0.3 mm to 5 mm. The farther the electrode member is driven in distal direction within the housing, in particular the through hole, the deeper the electrode member penetrates the tissue. So, when driving the electrode further within the housing in distal direction, the electrode member may penetrate the tissue over its whole length.

[0023] The IMD may have a cylindrical shape with a longitudinal axis extending from the proximal end of the housing to the distal end of the housing. In particular, the housing may have a cylindrical shape. The housing may have an inner tube surrounding the through hole. In other words, the through hole of the housing may be formed by a hollow tube of the housing. So, the housing may comprise the tube and a hollow cylinder for accommodating the electronic circuit, the energy source, and the tube. In addition, the IMD, in particular the housing, may be fluid-tightly sealed against its surroundings. The housing may comprise or may be made of metal. The dimensions of the housing may be designed for implantation within the ventricle of a heart.

[0024] The IMD as described in this description represents a leadless conduction system pacemaker (LCSP) concept optionally utilizing a tine-based fixation mechanism. It is comprised of two

[0025] 24.131P-WO / 08.12.2025 components. One of these components which may be referred to as Implantable Pulse Generator (IPG), comprises the housing, the energy source and the electronic circuit. A second one of these components comprises or is the electrode member which comprises or holds the second electrode. The most distal part of the IPG may be the tip of the electrode member.

[0026] The LCSP may be fixed to the tissue via delivery catheter in two instances into the ventricular septum. A first step instance involves the above mentioned arranging of the IMD in the body by deploying and fixating the tines in the tissue. This may be done with the electrode member in a retracted state. It may have an initial protrusion, e.g., the tip, to begin the process of reaching the conduction system, but it will be mostly in a retracted state. A second instance involves driving the electrode member further in distal direction relative to the housing and thereby deeper penetrating the tissue by the electrode member. This may be done iteratively and stopped whenever the conduction system is reached within each individual patient anatomy. So, when moving the electrode member further within the through hole relative to the housing, the electrode member may be driven in distal direction to deeper penetrate the tissue and may be driven in proximal direction to penetrate the tissue less.

[0027] According to an embodiment, the electrode member has an outer thread at a lateral surface of the electrode member; an inner thread mating the outer thread is formed at an inner wall surrounding the through hole of the housing; the electrode member is mechanically coupled to the housing by the threads; and the electrode member is arrangeable within the through hole of the housing at the varying depths depending on how far the electrode member is screwed into the through hole of the housing by the threads. The threads enable to move the electrode member relative to the housing and to arrange the electrode member within the housing at varying depths in an easy and controllable manner. This enables to arrange the second electrode at varying depths within the tissue in an easy and controllable manner. That the electrode member is screwed into the through hole of the housing may mean that the electrode member may be driven within the through hole in distal direction relative to the housing. In contrast, when retracting the electrode member from the tissue, the electrode member may be driven in proximal direction relative to the housing. The outer thread mates

[0028] 24.131P-WO / 08.12.2025 to the inner thread such that the outer thread may be screwed into the inner tread. The inner wall surrounding the through hole may be the inner wall of the tube of the housing.

[0029] The second instance mentioned above may involve driving the electrode member further in distal direction relative to the housing and thereby deeper penetrating the tissue by the electrode member by rotating the electrode member with respect to the housing what will telescope the second electrode deeper into the tissue. A catheter for implanting the IMD will allow for close to a 1 : 1 torque translation to control the deployment of the second electrode into the tissue to avoid risk of perforating into the left ventricle. This avoids an issue of the prior art IMDs with respect to torque buildup and unexpected torque breakthrough which make the electrode deployment unpredictable and risking perforations. In contrast, the torque translation being closer to a 1 : 1 ratio may contribute to provide a controlled rotational deployment of the electrode member and thereby the pacing electrode, i.e., the second electrode.

[0030] According to an embodiment, the IMD comprises a positioning element having an outer thread at its lateral surface and at least partly being arranged within the through hole such that a distal end of the positioning element is mechanically coupled to a proximal end of the electrode member, wherein an inner wall surrounding the through hole has an inner thread mating the outer thread, wherein the positioning element and thereby the electrode member coupled thereto are arrangeable within the through hole of the housing at the varying depths depending on how far the positioning element is screwed into the through hole of the housing by the threads. The positioning element having the outer thread represents another alternative for driving the electrode member in distal direction relative to the housing in a controllable manner which has the same advantages as the above embodiment in which the electrode member is rotated. The positioning element may touch the electrode member. The positioning element may be fixedly attached to the electrode member. The positioning element is formed and arranged such that it drives the electrode member in distal direction when it is screwed into the through hole in distal direction. The positioning element may be formed and arranged such that it retracts the electrode member in proximal direction when it is screwed out of the through hole in proximal direction. The inner wall surrounding the through hole may be the inner wall of the tube of the housing.

[0031] 24.131P-WO / 08.12.2025 In case of the positioning element being rotated and driving the electrode member, the second instance mentioned above may involve driving the electrode member further in distal direction relative to the housing and thereby deeper penetrating the tissue by the electrode member by rotating the positioning element with respect to the housing what will telescope the electrode member and thereby the second electrode deeper into the tissue.

[0032] According to an embodiment, the electrode member is arrangeable within the through hole at the varying depths by an interference fit between the electrode member and the through hole. This embodiment represents a friction-based translation mechanism. So, the electrode member may be held within the through hole by friction. Instead of mating the electrode member to the housing of the IPG with threads, there may be a press-fit interaction between the electrode member and the tube surrounding the through hole. In this case, the electrode member may be pushed in distal direction or may be retracted in proximal direction by a stylet. The stylet may be a part of a catheter for implanting the IMD. Alternatively, the stylet may be a component of the IMD and may be grabbed and / or rotated by the catheter. During deployment, the tines may be anchored to the tissue, then the housing may be held in place by the catheter tip / protector cup, and the electrode member may be pushed into the heart tissue by the stylet until the pacing electrode on the electrode member reaches the conduction system of the heart. This can also be controlled by a locking mechanism where the IPG is mated to the electrode member via a keyed lock.

[0033] According to an embodiment, the electrode member has a locking part at its proximal end; the locking part corresponds to a counter-locking part at the stylet for moving the electrode member within the through hole; and the locking part and the counter-locking part are formed such that the electrode member is pushable, pullable, and / or rotatable by the stylet when the locking part is mechanically coupled to the counter-locking part. In case of the electrode member being driven relative to the housing by the positioning element, the locking part may be formed at a proximal end of the positioning element. The locking part and the counter-locking part may form a locking mechanism. The locking mechanism enables to fixedly arrange the stylet at the electrode member such that the electrode member may be rotated, pushed, and / or pulled relative to the housing by the stylet. The locking

[0034] 24.131P-WO / 08.12.2025 mechanism may principally work by a form-fit, e.g., corresponding to a bayonet attachment. For example, the counter-locking part of the stylet may be inserted into the locking part of the electrode member. Then, counter-locking part may be rotated within the locking part, e.g., at about 90 degrees, such that the counter-locking part engages in the locking part. For example, the locking part may comprise a protrusion under which the counter-locking part may be rotated such that the counter-locking part is engaged in the locking part. Then, the stylet cannot be separated from the electrode member, or alternatively from the positioning element, by pushing or pulling it parallel to the distal direction. Then, a translational pushingforce in distal direction or a retraction pulling-force in proximal direction may be transferred to the electrode member by the stylet to position the electrode member at varying depth within the through hole of the housing. To remove the stylet it may be rotated back 90 degrees and may be withdrawn from the electrode member in proximal direction.

[0035] According to an embodiment, the implantable medical device comprises: a coiled connector being arranged within the through hole proximally with respect to the electrode member, being mechanically coupled with the electrode member and being electrically coupled to the second electrode; and an extended connector being electrically coupled to the electronic circuit and extending from the electronic circuit to the coiled connector such that the extended connector electrically contacts the coiled connector. The electrode member may be mechanically coupled with the coiled connector such that a rotation of the electrode member is transferred to a rotation of the coiled connector. When rotating the coiled connector, the extended connector stays in physical contact with the coiled connector, even when the coiled connector as a whole is driven in distal or proximal direction. This enables to keep the electric contact between the second electrode and the electronic circuit by the coiled and extended connectors independent from the axial position of the electrode member with respect to the housing. The coiled connector may be arranged such that a longitudinal axis of the coiled connector is parallel or identical to a longitudinal axis of the housing and / or the through hole. In case of the electrode member being positioned within the through hole by the positioning element, the coiled connector may be arranged between the positioning element and the electrode member. In case of the electrode member being positioned within the through hole by the stylet, the coiled connector may surround a free volume through which the stylet may extend to the electrode member.

[0036] 24.131P-WO / 08.12.2025 According to an embodiment, the energy source and the electronic circuit are arranged one after the other in distal direction and the through hole extends through the energy source and the electronic circuit. In this case, the energy source and the electronic circuit are stacked above each other, in case of the IMD being arranged such that its axis is vertically oriented. Alternatively, the energy source and the electronic circuit are arranged perpendicularly to the distal direction next to each other and the through hole extends between the energy source and the electronic circuit. In this case, the energy source and the electronic circuit are arranged horizontally next to each other, in case of the IMD being arranged such that its axis is vertically oriented.

[0037] According to an embodiment, the electrode member has a sharp tip at its distal end. In other words, the tip may be spiky or pointed. The sharp tip may enable to penetrate the tissue easily and with minimal impact on the tissue.

[0038] According to an embodiment, a distal end region of the electrode member is spear-shaped; or the distal end region is helically shaped. The spear-shaped electrode member may be referred to as “electrode spear” or “electrode rod”. The spear-shape of the electrode member may contribute to easily penetrate the tissue of the patient and / or to penetrate the tissue of the patient over a long range, i.e., the length of the electrode member. The helically shaped distal end region of the electrode member may consist of a connection part coupled to the housing, of the tip facing away from the housing, and of a helical section or helix extending from the connection part to the tip. The helically shaped electrode member may be screwed into the tissue when driving the electrode member in distal direction relative to the housing. As such, the helically shaped electrode member may contribute to fix the implantable medical device at the tissue of the patient. In any case, the electrode member may be formed and arranged such that it may penetrate the ventricular septum when arranging the IMD at the tissue of the patient. The distal end region may range from the distal end of the electrode member in proximal direction. A length of the distal end region may be in a range from 0.1% to 20% of the length of the electrode member, e.g., from 0.5% to 10%, e.g., from 1% to 5%. If the distal end region is helically shaped, the length of the distal end region may be in a

[0039] 24.131P-WO / 08.12.2025 range of 0.1-% to 95% of the length of the electrode member, in particular from 0.5% to 70%, in particular from 0.5% to 10%, in particular from 1% to 5%.

[0040] According to an embodiment, the second electrode is arranged within the distal end region of the electrode member. In particular, the second electrode may be formed at the tip and / or the tip may be formed by the second electrode. This enables to insert the second electrode at a maximal depth within the tissue. In addition, this allows the pacing electrode to penetrate the septum easily, in particular by a sharp and robust penetration of the tissue. Further, a large bipolar vector with fixed spacing may be provided by the second electrode being arranged at the tip of the electrode member. This may contribute to a very good atrial sensing and AV synchrony (pacing of the ventricle depending on the atrial activity / sensing), while the vector is maintained regardless of the pacing electrode depth.

[0041] According to an embodiment, the IMD comprises a hitch for grabbing the housing, wherein the hitch is arranged at a proximal end of the housing. The hitch may enable to insert or to retract the housing from the body.

[0042] According to an embodiment, the IMD comprises two or more tines being arranged at the distal end of the housing, protruding from the housing at least partly in distal direction, and being configured for attaching the implantable medical device to a tissue of a patient. The tines enable to fix the IMD to the tissue securely.

[0043] According to an embodiment, the implantable medical device is arranged at the tissue of the patient such that at least the tip of the electrode member penetrates the tissue. This may enable to contact the tissue early and to perform a pace mapping prior to implantation. In addition, this may enable to begin the process of reaching the conduction system.

[0044] According to an embodiment, the method comprises: testing whether the second electrode is arranged at the depth within the tissue as intended for its use, after the implantable medical device is arranged within the body; inserting the electrode member further into the through hole when the electrode member is not arranged deep enough within the tissue as intended for its use; and retracting the electrode member from the through hole when the electrode

[0045] 24.131P-WO / 08.12.2025 member is arranged too deep within the tissue as intended for its use. This enables to simply test whether the second electrode is arranged at the depth within the tissue as intended for its use. For example, it may be tested whether the second electrode is arranged at the depth within the tissue as intended for its use, by applying a voltage over the first and second electrodes by the electronic circuit and the energy source and by monitoring and analyzing a current flow through the first and second electrodes resulting from the applied voltage. The analyzing of the current may involve one or more impedance measurements which may be collected continually or iteratively to indicate any perforations of the electrode member within the left ventricle.

[0046] In the following, advantageous embodiments of the invention will be described with reference to the enclosed drawings. However, neither the drawings nor the description shall be interpreted as limiting the invention.

[0047] Fig. 1 shows a cross-sectional side view of an exemplary embodiment of an implantable medical device.

[0048] Fig. 2 shows the implantable medical device of figure 1 in two different states.

[0049] Fig. 3 shows a detailed cross-sectional side view of an exemplary embodiment of an implantable medical device.

[0050] Fig. 4 shows a cross-sectional side view of a of an exemplary embodiment of an implantable medical device.

[0051] Fig. 5 shows a cross-sectional side view of an exemplary embodiment of an implantable medical device.

[0052] Fig. 6 shows a side view of an exemplary embodiment of a coiled connector of one of the implantable medical devices.

[0053] 24.131P-WO / 08.12.2025 Fig. 7 shows a top view and a perspective view of an exemplary embodiment of a locking mechanism, each in two different states a) and b).

[0054] Fig. 8 shows a cross-sectional side view of an exemplary embodiment of an implantable medical device and two different cross-sectional top views of the implantable medical device.

[0055] Fig. 9 shows a cross-sectional side view of an exemplary embodiment of an implantable medical device and a cross-sectional top view of the implantable medical device.

[0056] Fig. 10 shows a flow-chart of an exemplary embodiment of a method for implanting the implantable medical device.

[0057] The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

[0058] Fig- 1 shows a cross-sectional side view of an exemplary embodiment of an implantable medical device (IMD) 20. Fig. 2 shows the IMD 20 of figure 1 in two different states. The IMD 20 may be an implantable intracardiac device, such as e.g. an implantable intracardiac pacemaker, in particular an Active Intracardiac Medical Device (AIMD), also known as implantable leadless pacemaker (ILP), which may be entirely implanted into a tissue 42 of a heart’s chamber or atrium of a patient. The patient may be a human or an animal.

[0059] The IMD 20 comprises a housing 22, a first electrode 30 exposed to surroundings of the IMD 20, an electronic circuit 46 (see figs. 8 and 9) arranged within the housing 22, an energy source 48 arranged within the housing 22, and an electrode member 32. The housing 22 has a proximal end 26, a distal end 28, and a tube 24 extending from the proximal end 26 to the distal end 28. The IMD 20 may have a cylindrical shape with a longitudinal axis extending from the proximal end 26 of the housing 22 to the distal end 28 of the housing 22. In particular, the housing 22 may have a cylindrical shape.

[0060] 24.131P-WO / 08.12.2025 The tube 24 surrounds a through hole 50 extending through the housing 22, in particular the tube 24, from the proximal end 26 of the housing 22 to the distal end 28 of the housing 22. In other words, the through hole 50 of the housing 22 may be formed by the hollow tube 42 of the housing 22. So, the housing 22 may comprise the tube 24 and a hollow cylinder for accommodating the electronic circuit 46, the energy source 48, and the tube 24. The housing 22 and / or in particular the tube 24 may comprise or may be made of metal. The housing 22 may be fluid-tightly sealed against its environment. The housing 22 may comprise or may be made of metal, in particular titanium.

[0061] The electrode member 32 has at least one second electrode 36 exposed to the surroundings of the IMD 20. The second electrode 32 is electrically coupled to the electronic circuit 46. The electrode member 32 is at least partly arranged within the through hole 50 of the housing 22, in particular of the tube 24, such that it protrudes from the housing 22 at the distal end 26 in distal direction and such that it is arrangeable within the through hole 50 at varying depths. A length over which the electrode member 32 protrudes from the housing 22 at the distal end 28 in distal direction depends on how far the electrode member 32 is arranged within the through hole 50 of the housing 22.

[0062] The electrode member 32 may extend through the through hole 50 such that at least a tip 34 of the electrode member 32 protrudes from the housing 22 at the distal end 28 of the housing 22. The electrode member 32 may comprise or may be made of an electrically conductive material. The electrode member 32 may be electrically insulated against its surroundings, except for the second electrode 36. The electrode member 32 may be either flexible or rigid. The electrode member 32 may have a length in a range from 3 mm to 30 mm, e.g., from 5 mm to 20 mm. The farther the electrode member 32 is driven in distal direction within the housing 22, in particular within the through hole 50, the deeper the electrode member 32 penetrates the tissue 42. So, when arranging the IMD 20 at the tissue 42, the electrode member 32 may be in a retracted state, as in a first state depicted in figure 2 at the right. Then, when driving the electrode member 32 further within the housing 22 in distal direction, the electrode member 32 may penetrate the tissue 42 over its whole length, e.g., as in a second state depicted in figure 1, and in figure 2 at the left. In the first state, the electrode

[0063] 24.131P-WO / 08.12.2025 member 32 may penetrate the tissue 42 up to a first depth DI. In the second state, the electrode member 32 may penetrate the tissue 42 up to a second depth D2.

[0064] The second electrode 36 may be arranged at a distal end of the electrode member 32. The second electrode 36 is electrically coupled to the electronic circuit 46. The second electrode 36 may be directly connected to the energy source 48 or may be coupled to the energy source 48 via the electronic circuit 46. The second electrode 36 may be a cathode. The second electrode 36 may comprise or may be made of platinum and / or iridium. The first electrode 30 may act as a return electrode or anode. Alternatively, the second electrode 36 may be an anode and the first electrode 30 may be a cathode. The second electrode 36 may be referred to as pacing electrode. The second electrode 36 may be extended to provide a means for accessing the conduction system, e.g., HIS bundle or Left bundle branch).

[0065] The electrode member 32 may be spear-shaped, as shown in figure 1. In particular, a distal end region of the electrode member 32 may be spear-shaped. The spear-shaped electrode member 32 may be referred to as “electrode spear” or “electrode rod”. The electrode member 32 may comprise a sharp tip 34 at a distal end of the electrode member 32. In other words, the tip 34 may be spiky or pointed. The distal end of the electrode member 32 which has the sharp tip 34 may be the same distal end at which the second electrode 36 is arranged. In particular, the second electrode 36 may be formed at the tip 34 or the tip 34 may be formed by the second electrode 36. The distal end region may range from the distal end of the electrode member 32 in proximal direction. A length of the distal end region may be in a range from 0.1% to 20% of the length of the electrode member, e.g., from 0.5% to 10%, e.g., from 1% to 5%. The second electrode 36 may be arranged within the distal end region of the electrode member 32. For example, the range over which the second electrode 36 ranges starting from the tip 34 may correspond to the distal end region of the electrode member 32.

[0066] The electrode member 32 may have an outer thread 44 at a lateral surface of the electrode member 32. It has to be mentioned in this context that any “lateral” surface of a body always refers to an outer lateral surface of the corresponding body in this description. An inner thread 52 mating the outer thread 44 may be formed at an inner wall of the tube 24, in particular the through hole 50, of the housing 22. The outer thread 44 mates to the inner

[0067] 24.131P-WO / 08.12.2025 thread 52 such that the outer thread 44 may be screwed into the inner tread 52. The electrode member 32 may be mechanically coupled to the housing 22 by the threads 44, 52. The electrode member 32 is arrangeable within the through hole 50 of the housing 22 at the varying depths depending on how far the electrode member 32 is screwed into the through hole 50 of the housing 22 by the threads 44, 52. That the electrode member 32 is screwed into the through hole 50 of the housing 22 may mean that the electrode member 32 may be driven within the through hole 50 in distal direction relative to the housing 22. In contrast, when retracting the electrode member 32 from the tissue 42, the electrode member 32 may be driven in proximal direction relative to the housing 22.

[0068] The IMD 20 may comprise two or more tines 40 for fixing the IMD 20 to the tissue 42, as it is known in the art. The tines 40 may be arranged at the distal end 28 of the housing 22. The tines 40 may at least partly extend in distal direction.

[0069] The IMD 20 may comprise a hitch 38 for grabbing the housing 22. The hitch 38 may be fixedly arranged at the housing 22 at the proximal end 26 of the housing 22. The hitch 38 may be arranged at the housing 22 such that the hitch 38 cannot be rotated relative to the housing 22. For example, the hitch 38 and at least a part of the housing 22 may be made of one piece. The hitch 38 may enable to insert or to retract the housing 22 from the body of the patient, e.g., by a catheter.

[0070] The electronic circuit 46 is arranged within the housing 22 and is electrically coupled to the energy source 48 and the first electrode 30. The energy source 48 may be a battery. The first electrode 30 may be directly connected to the energy source 48 or may be coupled to the energy source 48 via the electronic circuit 46.

[0071] When arranging the IMD 20 in the body such that at least a part of the electrode member 32 penetrates the tissue 42, the electrode member 32 may penetrate the tissue 42 at the first depth DI, e.g., ranging from 0 mm (excluded) to 10 mm, e.g., from 1 mm to 8 mm, corresponding to the first state of the IMD 20 shown in figure 2 at the right. The farther the electrode member 32 is driven in distal direction relative to the housing 22, in particular by screwing the electrode member 32 farther into the tube 24, the deeper the electrode member

[0072] 24.131P-WO / 08.12.2025 32 penetrates the tissue 42. So, when inserting the electrode member 32 further into the tube 24 in distal direction, the electrode member 32 may penetrate the tissue 42 over its whole length, e.g., up to the second depth D2, corresponding to the second state of the IMD 20 shown in figure 2 at the left.

[0073] The IMD 20 represents a leadless conduction system pacemaker (LCSP) concept utilizing a tine-based fixation mechanism, i.e., the tines 40. It is comprised of two components. One of these components may be referred to as Implantable Pulse Generator (IPG). The IPG comprises the housing 22, the energy source 48, the electronic circuit 46, and the tines 40. The most distal part of the IPG may be the distal end 28 of the housing 22 or the tines 40. A second one of these components comprises or is the electrode member 32 which is arrangeable at varying depths within the tube 24 of the housing 22.

[0074] Optionally, the IMD 20 may comprise two or more further second electrodes 36 at the electrode member 32, with each of the further second electrodes 36 being exposed to the surroundings of the IMD 20. The first and second electrodes 30, 36 enable to form a first electric field within the body. The first electrode 30 and in case the further second electrodes 36 correspondingly form two or more further electric fields within the body. The further second electrodes 36 may be arranged more proximal on the electrode member 32 than the second electrode 36 mentioned further above, e.g., to provide more areas of pacing capture along the septum. Optionally, additional first electrodes 30 may be arranged at the housing 22 to provide additional vectors of corresponding electric fields.

[0075] Fig. 3 shows a detailed cross-sectional side view of an exemplary embodiment of an IMD 20, e.g., of the IMD 20 described with respect to figures 1 and 2. The IMD 20 may comprise a coiled connector 54 being arranged within the through hole 50 proximally with respect to the electrode member 32. The coiled connector 54 may be mechanically coupled to the electrode member 32. The coiled connector 54 may be electrically coupled to the second electrode 32, e.g., via the electrode member 32. In addition, the IMD 20 may comprise an extended connector 56. The extended connector 56 may be electrically coupled to the electronic circuit 46. The extended connector 56 may extend from the electronic circuit 46 to the coiled connector 54 such that the extended connector 56 electrically contacts the coiled

[0076] 24.131P-WO / 08.12.2025 connector 54. The coiled connector 54 may be mechanically coupled with the electrode member 32 such that a rotation of the electrode member 32 is transferred to a rotation of the coiled connector 54. When rotating the coiled connector 54, the extended connector 56 stays in physical contact with the coiled connector 54, even when the coiled connector 54 as a whole is driven in distal or proximal direction by the rotation. The coiled connector 54 may be arranged such that a longitudinal axis of the coiled connector 54 is parallel or identical to the longitudinal axis of the housing 22, the tube 24, and / or the through hole 50.

[0077] Fig. 4 shows a cross-sectional side view of a of an exemplary embodiment of an IMD 20. The IMD 20 shown in figure 4 may widely correspond to the IMD 20 described with respect to figures 1 to 3. Therefore, in order to provide a concise description of and to avoid unnecessary repetitions, only those features of the IMD 20 shown in figure 4 are described in the following, in which the IMD 20 shown in figure 4 differs from the IMD 20 described with respect to figures 1 to 3.

[0078] The IMD 20 may comprise a positioning element 60. The positioning element 60 may at least partly be arranged within the through hole 50 such that a distal end 62 of the positioning element 60 is mechanically coupled to a proximal end 64 (see figure 5) of the electrode member 32. The positioning element 60 may touch the electrode member 32. The positioning element 60 may be fixedly attached to the electrode member 32. In this embodiment, it may be that the outer thread 44 is not formed at the electrode member 32 but at a lateral surface of the positioning element 60. The tube 40, in particular the through hole 50, may still have the inner thread 52 at its inner wall, with the inner thread 52 mating the outer thread 44 at the positioning element 60. The positioning element 60 and thereby the electrode member 32 coupled thereto are arrangeable within the through hole 50 of the housing 22 at the varying depths DI, D2 depending on how far the positioning element 60 is screwed into the through hole 50 of the housing 22 by the threads 44, 52. The positioning element 60 having the outer thread 44 represents an alternative for driving the electrode member 32 in distal direction relative to the housing 22 in a controllable manner. The positioning element 60 may be formed and arranged such that it drives the electrode member 32 in the distal direction when it is screwed into the through hole 50 in distal direction. The positioning

[0079] 24.131P-WO / 08.12.2025 element 60 may be formed and arranged such that it retracts the electrode member 32 in proximal direction when it is screwed out of the through hole 50 in proximal direction.

[0080] In case of the positioning element 60 being rotated and driving the electrode member 32, the second instance mentioned above may involve driving the electrode member 32 further in distal direction relative to the housing 22 and thereby deeper penetrating the tissue 42 by the electrode member 32 by rotating the positioning element 60 with respect to the housing 22 what will telescope the electrode member 32 and thereby the second electrode 46 deeper into the tissue 42.

[0081] In case of the electrode member 32 being positioned within the through hole 50 by the positioning element 60, the coiled connector 54 may be arranged between the positioning element 60 and the electrode member 32.

[0082] Optionally, the distal end region of the electrode member 32 may be helically shaped, as it is known in the art. The helically shaped distal end region of the electrode member 32 may consist of a connection part coupled to the housing 22, of the tip 34 facing away from the housing 22, and of a helical section or helix extending from the connection part to the tip 34. The helically shaped distal end region may be screwed into the tissue 42 when inserting the electrode member 32 farther into the tube 24. As such, the helically shaped distal end region of the electrode member 32 may contribute to fix the IMD 20 at the tissue 42 of the patient. In any case, the electrode member 32 may be formed and arranged such that it may penetrate the ventricular septum of the patient.

[0083] In another embodiment (not shown), the distal end region of the electrode member 32 of the IMD 20 shown in figures 1 and 2 may be helically shaped, as shown in figure 4. In another embodiment (not shown), the distal end region of the electrode member 32 of the IMD 20 shown in figure 4 may comprise the spear-shaped tip 34 of the IMD 20 shown in figures 1 and 2.

[0084] Fig. 5 shows a cross-sectional side view of an exemplary embodiment of an IMD 20. The IMD 20 shown in figure 5 may widely correspond to the IMDs 20 described with respect to

[0085] 24.131P-WO / 08.12.2025 figures 1 to 4. Therefore, in order to provide a concise description of and to avoid unnecessary repetitions, only those features of the IMD 20 shown in figure 5 are described in the following, in which the IMD 20 shown in figure 5 differs from the IMD 20 described with respect to figures 1 to 4.

[0086] As an alternative to the threads 44, 52, the electrode member 32 may be arrangeable within the through hole 50 at the varying depths by an interference fit between the electrode member 32 and the through hole 50. This embodiment may represent a friction-based translation mechanism. So, the electrode member 32 may be held within the through hole 50 by friction. Instead of mating the electrode member 32 to the housing 22 of the IPG with the threads 44, 52, there may be a press-fit interaction between the electrode member 32 and the tube 24 surrounding the through hole 50. For example, an outer diameter of the electrode member 32 may fit to an inner diameter of the tube 24 and thereby of the diameter of the through hole 50.

[0087] In this case, the electrode member 32 may be pushed in distal direction or may be retracted in proximal direction by a stylet 58. The stylet 58 may be a part of a catheter (not shown) for implanting the IMD 20 into the body. Alternatively, the stylet 58 may be a component of the IMD 20 and may be grabbed and / or rotated by the catheter. During deployment, the tines 40 may be anchored to the tissue 42, then the housing 22 may be held in place by a tip / protector cup of the catheter, and the electrode member 32 may be pushed into the tissue 42 of the heart by the stylet 58 until the pacing electrode, i.e., the second electrode 36, on the electrode member 32 reaches the conduction system of the heart. This can also be controlled by a locking mechanism where the IPG is mated to the electrode member 32 via a keyed lock (not shown).

[0088] Fig. 6 shows a side view of an exemplary embodiment of a coiled connector 54 of one of the IMDs 20 described above. In particular, in case of the electrode member 32 being positioned within the through hole 50 by the stylet 58, as shown in figure 5, and in case of the second electrode 36 being electrically coupled to the electronic circuit 46 by the coiled connector 54, as described with respect to figure 3, the coiled connector 54 may surround a free volume

[0089] 24.131P-WO / 08.12.2025 68 through which the stylet 58 may extend from the proximal end 26 of the housing 22 to the electrode member 32.

[0090] Fig. 7 shows a top view and a perspective view of an exemplary embodiment of a locking mechanism 66, each in two different states a) and b). In particular, figure 7 shows a first state of the locking mechanism 66 on the left side and a second state of the locking mechanism 66 on the right side. In each of the states a) and b) the top view is shown above the corresponding perspective view. The locking mechanism 66 may be used to couple the stylet 58 with the electrode member 32 or, in case, with the positioning element 60.

[0091] The locking mechanism has a locking part 72 and a counter-locking part 74. The locking part 72 may be arranged at the proximal end 64 of the electrode member 32 and the counterlocking part 72 may be arranged at the distal end 70 of the stylet 58. The locking part 72 corresponds to the counter-locking part 74. The locking mechanism 66 may enable to move the electrode member 32 or, in case, the positioning element 60, within the through hole 50 by the stylet 58. In particular, the locking part 72 and the counter-locking part 74 may be formed such that the electrode member 32 is pushable, pullable, and / or rotatable by the stylet 58 when the locking part 72 is mechanically coupled, in particular engaged, to the counterlocking part 74. In case of the electrode member 32 being driven relative to the housing 22 by the positioning element 60, the locking part 72 may be formed at a proximal end of the positioning element 60. The locking mechanism 66 may enable to fixedly arrange the stylet 58 at the electrode member 32 such that the electrode member 32 may be rotated, pushed, and / or pulled relative to the housing 22 by the stylet 58.

[0092] The locking mechanism 66 may principally work by a form-fit, e.g., corresponding to a bayonet attachment. For example, the counter-locking part 74 of the stylet 58 may be inserted into the locking part 72 of the electrode member 32, as shown in the first state a). Then, counter-locking part 74 may be rotated within the locking part 72, e.g., at about 90 degrees, such that the counter-locking part 74 engages in the locking part 72. For example, the locking part 72 may comprise a protrusion under which the counter-locking part 74 may be rotated such that the counter-locking part 74 is engaged in the locking part 72 after the rotation. Then, the stylet 58 cannot be separated from the electrode member 32, or alternatively from

[0093] 24.131P-WO / 08.12.2025 the positioning element 60, by pushing or pulling it parallel to the distal direction. Then, a translational pushing-force in distal direction or a retraction pulling-force in proximal direction may be transferred to the electrode member 32 by the stylet 58 to position the electrode member 32 at varying depth within the through hole 50 of the housing 22. To remove the stylet 58 it may be rotated back 90 degrees and may be withdrawn from the electrode member 32 in proximal direction.

[0094] Fig. 8 shows a cross-sectional side view of an exemplary embodiment of an IMD 20 and two different cross-sectional top views of the IMD 20. The cross-sectional side view of the IMD 20 shows the embodiment of the IMD 20 described with respect to figure 5. However, the two different cross-sectional top views may also be taken from one of the other embodiments of the IMD 20 described above. In other words, the IMDs 20 explained with respect to figures 1 to 4 may also have cross-sections as shown in figure 8 on the left.

[0095] In this embodiment, the energy source 48 and the electronic circuit 46 are arranged one after the other in distal direction and the tube 24, in particular the through hole 50, extends through the energy source 48 and the electronic circuit 46. In this case, the energy source 48 and the electronic circuit 46 may be stacked above each other, in case of the IMD 20 being arranged such that its axis is vertically oriented.

[0096] Fig. 9 shows a cross-sectional side view of an exemplary embodiment of an IMD 20 and a cross-sectional top view of the IMD 20. The cross-sectional side view of the IMD 20 shows the embodiment of the IMD 20 described with respect to figure 5. However, the two different cross-sectional top views may also be taken from one of the other embodiments of the IMD 20 described above. In other words, the IMDs 20 explained with respect to figures 1 to 4 may also have cross-sections as shown in figure 9 on the left.

[0097] In this embodiment, the energy source 48 and the electronic circuit 46 are arranged perpendicularly to the distal direction next to each other and the tube 24, in particular the through hole 50, extends between the energy source 48 and the electronic circuit 46. In this case, the energy source 48 and the electronic circuit 46 are arranged horizontally next to each other, in case of the IMD 20 being arranged such that its axis is vertically oriented.

[0098] 24.131P-WO / 08.12.2025 Fig. 10 shows a flow-chart of an exemplary embodiment of a method for implanting the IMD 20.

[0099] In a step S2, the IMD 20 may be provided such the electrode member 32 is at least partly arranged within the through hole 50 of the housing 22 such that it protrudes from the housing 22 at the distal end 28 in distal direction.

[0100] In a step S4, the IMD 20 may be arranged at the tissue 42 within the body of the patient, e.g., by the tines 50, as it is known in the art. For example, the IMD 20 may be arranged at the tissue 42 of the patient such that at least the tip 34 of the electrode member 32 penetrates the tissue 42. The IMD 20 may be implanted within the body via a delivery catheter. The IMD 20 may be implanted into the ventricular septum. Optionally, prior to deployment, a pace mapping may be carried out via the second electrode 36 at the tip 34 or via electrodes embedded in a protector cup of the delivery catheter (not shown) to establish a target location.

[0101] In an optional step S6, it may be tested whether the second electrode 36 is arranged at the depth within the tissue 42 as intended for its use. For example, it may be tested whether the second electrode 36 is arranged at the depth D2 within the tissue 42 as intended for its use, by applying a voltage over the first and second electrodes 30, 36 by the electronic circuit 46 and the energy source 48 and by monitoring and analyzing a current flow through the first and second electrodes 30, 36 resulting from the applied voltage. The analyzing of the current may involve one or more impedance measurements which may be collected continually to indicate any perforations of the electrode member within the left ventricle.

[0102] In a step S8, the electrode member 32 may be further inserted into the through hole 50 until the second electrode 36 at the electrode member 32 is arranged at the depth D2 within the tissue 42 as intended for its use, e.g., at the second depth D2. For example, when the optional step S6 has been carried out, the electrode member 32 may be driven further in distal direction relative to the housing 22 when the test result is that the electrode member 32 is not arranged deep enough within the tissue 42 as intended for its use. Alternatively, the

[0103] 24.131P-WO / 08.12.2025 electrode member 32 may be retracted relative the housing 22 in proximal direction when the electrode member 32 is arranged too deep within the tissue 42 as intended for its use.

[0104] Vividly spoken, the IMD 20 may be fixed to the tissue 42 in two instances. A first instance involves the above mentioned arranging of the IMD 20 in the body by deploying and fixating the tines 40 in the tissue 42. This may be done with the electrode member 32 in a retracted state, at least mostly in a retracted state, e.g., as shown in figure 2 on the right, wherein the distal end of the electrode member 32, e.g., the tip 34 and / or the second electrode 36, may be arranged within the tissue 42 to begin the process of reaching the conduction system. The second instance involves driving the electrode member 32 further in distal direction with respect to the housing 22 and thereby deeper penetrating the tissue 42 by the electrode member 32 including the second electrode 36, e.g., in case of the threads 44, 52 by rotating the electrode member 32 or, in case, the positioning element 60, with respect to the housing 22 what will telescope the second electrode 36 deeper into the tissue 42. This may be done iteratively, e.g., under one or more test sequences as described in optional step S6 and may be stopped whenever the conduction system is reached within each individual patient anatomy. The delivery catheter will allow for close to a 1 : 1 torque translation to control the deployment of the second electrode 36 into the tissue 42 to avoid risk of perforating into the left ventricle.

[0105] Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0106] 24.131P-WO / 08.12.2025 List of Reference Numerals

[0107] 20 IMD

[0108] 22 housing

[0109] 24 tube

[0110] 26 proximal end of housing

[0111] 28 distal end of housing

[0112] 30 first electrode

[0113] 32 electrode member

[0114] 34 tip

[0115] 36 second electrode

[0116] 38 hitch

[0117] 40 tine

[0118] 42 tissue

[0119] 44 outer thread

[0120] 46 electronic circuit

[0121] 48 energy source

[0122] 50 through hole

[0123] 52 inner thread

[0124] 54 coiled connector

[0125] 56 extended connector

[0126] 58 stylet

[0127] 60 positioning element

[0128] 62 distal end of positioning element

[0129] 64 proximal end of electrode member

[0130] 66 locking mechanism

[0131] 68 free volume

[0132] 70 distal end of stylet

[0133] 72 locking part

[0134] 74 counter-locking part

[0135] DI first depth

[0136] D2 second depth

[0137] 24.131P-WO / 08.12.2025

Claims

Claims1. Implantable medical device (20), comprising: a housing (22) having a distal end (28), a proximal end (26), and a through hole (50) extending from the proximal end (26) to the distal end (28); a first electrode (30) being arranged at the housing (22) between the proximal end (26) and the distal end (28) and being exposed to surroundings of the implantable medical device (20); an energy source (48) arranged within the housing (22); an electronic circuit (46) arranged within the housing (22) and electrically coupled to the energy source (48) and the first electrode (30); and an electrode member (32) having at least one second electrode (36) exposed to the surroundings of the implantable medical device (20), with the second electrode (36) being electrically coupled to the electronic circuit (46), wherein the electrode member (32) is at least partly arranged within the through hole (50) of the housing (22) such that it protrudes from the housing (22) at the distal end (28) in distal direction and such that it is arrangeable within the through hole (50) at varying depths (DI, D2), wherein a length over which the electrode member (32) protrudes from the housing (22) at the distal end (28) in distal direction depends on how far the electrode member (32) is arranged within the through hole (50) of the housing (22).

2. Implantable medical device (20) in accordance with claim 1, wherein the electrode member (32) has an outer thread (44) at a lateral surface of the electrode member (32); an inner thread (52) mating the outer thread (44) is formed at an inner wall surrounding the through hole (50) of the housing (22); the electrode member (32) is mechanically coupled to the housing (22) by the threads (44, 52); and the electrode member (32) is arrangeable within the through hole (50) of the housing (22) at the varying depths (DI, D2) depending on how far the electrode member (32) is screwed into the through hole (50) of the housing (22) by the threads (44, 52).24.131P-WO / 08.12.20253. Implantable medical device (20) in accordance with claim 1, comprising: a positioning element (60) having an outer thread (44) at its lateral surface and at least partly being arranged within the through hole (50) such that a distal end (62) of the positioning element (60) is mechanically coupled to a proximal end (64) of the electrode member (32), wherein an inner wall surrounding the through hole (50) has an inner thread (52) mating the outer thread (44), wherein the positioning element (60) and thereby the electrode member (32) coupled thereto are arrangeable within the through hole (50) of the housing (22) at the varying depths (DI, D2) depending on how far the positioning element (60) is screwed into the through hole (50) of the housing (22) by the threads (44, 52).

4. Implantable medical device (20) in accordance with claim 1, wherein the electrode member (32) is arrangeable within the through hole (50) at the varying depths (DI, D2) by an interference fit between the electrode member (32) and the through hole (50).

5. Implantable medical device (20) in accordance with one of the preceding claims, wherein the electrode member (32) has a locking part (72) at its proximal end (64); the locking part (72) corresponds to a counter-locking part (74) at a stylet (58) for moving the electrode member (32) within the through hole (50); the locking part (72) and the counter-locking part (74) are formed such that the electrode member (32) is pushable, pullable, and / or rotatable by the stylet (58) when the locking part (72) is mechanically coupled to the counter-locking part (74).

6. Implantable medical device (20) in accordance with one of the preceding claims, comprising: a coiled connector (54) being arranged within the through hole (50) proximally with respect to the electrode member (32), being mechanically coupled with the electrode member (32) and being electrically coupled to the second electrode (36); and24.131P-WO / 08.12.2025an extended connector (56) being electrically coupled to the electronic circuit (46) and extending from the electronic circuit (46) to the coiled connector (54) such that the extended connector (56) electrically contacts the coiled connector (54).

7. Implantable medical device (20) in accordance with one of the preceding claims, wherein the energy source (48) and the electronic circuit (46) are arranged one after the other in distal direction and the through hole (50) extends through the energy source (48) and the electronic circuit (46), or the energy source (48) and the electronic circuit (46) are arranged perpendicularly to the distal direction next to each other and the through hole (50) extends between the energy source (48) and the electronic circuit (46).

8. Implantable medical device (20) in accordance with one of the preceding claims, wherein the electrode member (32) has a sharp tip (34) at its distal end (64).

9. Implantable medical device (20) in accordance with one of the preceding claims, wherein a distal end region of the electrode member (32) is spear-shaped; or the distal end region is helically shaped.

10. Implantable medical device (20) in accordance with claim 9, wherein the second electrode (36) is arranged within the distal end region of the electrode member (32).

11. Implantable medical device (20) in accordance with one of the preceding claims, comprising: a hitch (38) for grabbing the housing (22), wherein the hitch (38) is arranged at the proximal end (26) of the housing (22).

24. 131P-WO / 08.12.202512. Implantable medical device (20) in accordance with one of the preceding claims, comprising: two or more tines (40) being arranged at the distal end (28) of the housing (22), protruding from the housing (22) at least partly in distal direction, and being configured for attaching the implantable medical device (20) to a tissue (42) of a patient.

13. Method for implanting an implantable medical device (20) in accordance with one of the preceding claims into a body of a patient, the method comprising: providing the implantable medical device (20) with the electrode member (32) being at least partly arranged within the through hole (50) of the housing (22) such that it protrudes from the housing (22) at the distal end (28) in distal direction; arranging the implantable medical device (20) at the tissue (42) within the body of the patient; and moving the electrode member (32) further within the through hole (50) relative to the housing (22) until the second electrode (36) at the electrode member (32) is arranged at a depth (D2) within the tissue (42) as intended for its use.

14. Method in accordance with claim 13, wherein the implantable medical device (20) is arranged at the tissue (42) of the patient such that at least a tip (34) of the electrode member (32) penetrates the tissue (42).

15. Method in accordance with one of claims 13 or 14, comprising: testing whether the second electrode (36) is arranged at the depth (D2) within the tissue (42) as intended for its use, after the implantable medical device (20) is arranged within the body; inserting the electrode member (32) further into the through hole (50) when the electrode member (32) is not arranged deep enough within the tissue (42) as intended for its use; and retracting the electrode member (32) from the through hole (50) when the electrode member (32) is arranged too deep within the tissue (42) as intended for its use.24.131P-WO / 08.12.2025

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