WO2025201715A1

WO2025201715A1 - Header assembly for an implantable intracardiac device and respective intracardiac device

Info

Publication number: WO2025201715A1
Application number: PCT/EP2025/053103
Authority: WO
Inventors: Devan Hughes
Original assignee: Biotronik SE and Co KG
Current assignee: Biotronik SE and Co KG
Priority date: 2024-03-28
Filing date: 2025-02-06
Publication date: 2025-10-02
Anticipated expiration: 2026-09-28

Abstract

The invention refers to a header assembly (3) for an implantable intracardiac device (1) which is automated assembly friendly, wherein the header assembly comprises a cylindrical feedthrough arrangement (5), a ring-shaped proximal cap (7), a ring-shaped distal cap (9), a base ring (11) with at least two tines (13) protruding distally from the base ring, and a pressing arrangement (15). The feedthrough arrangement has an outer shell surface (17). The proximal cap comprises an inner surface (19). The distal cap comprises an outer surface (21). The distal cap comprises a fixing portion (23) with an inner surface (25), the inner surface forming a locking connection with the outer shell surface of the feedthrough arrangement for counteracting a movement of the distal cap and the feedthrough arrangement apart from each other in an axial direction (27). The proximal cap, the distal cap and the base ring are configured such that the inner surface of the proximal cap and the outer surface of the distal cap are arranged coaxially and directed towards each other, and the base ring is interposed between the inner surface of the proximal cap and the outer surface of the distal cap such as to be coaxially rotatable relative to the distal cap. The pressing arrangement is configured such as to exert an elastic force in a radial direction such as to press the base ring against one of the inner surface of the proximal cap and the outer surface of the distal cap. The proximal cap is made with a first material and the distal cap is made with a second material, the first material being softer than the second material.

Description

HEADER ASSEMBLY FOR AN IMPLANTABLE INTRACARDIAC DEVICE AND

RESPECTIVE INTRACARDIAC DEVICE

The present invention refers to an implantable intracardiac device, such as an implantable intracardiac pacemaker, and a header assembly therefor.

Active or passive medical devices such as implantable intracardiac devices, for example implantable intracardiac pacemakers (also known as leadless pacemakers), are well known miniaturized medical devices which are entirely implanted into a heart's ventricle or atrium. Intracardiac pacemakers are used for patients who suffer from a bradycardia, that is if a heart 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.

Documents US 2012/0172690 Al and US 10,112,045 B2 disclose a leadless pacemaker device which comprises a conductive housing, and a fixation element assembly. The fixation element assembly includes a set of active fixation tines and an insulator to electrically isolate the set of active fixation tines from the conductive housing of the implantable medical device. The active fixation tines in the set are deployable from a spring-loaded position in which distal ends of the active fixation tines point away from the implantable medical device to a hooked position in which the active fixation tines bend back towards the implantable medical device. The active fixation tines are configured to secure the implantable medical device to a patient’s tissue when deployed while the distal ends of the active fixation tines are positioned adjacent to the patient tissue.

However, known manufacturing methods for leadless pacemakers need sophisticated alignment methods to fix a tine array to a medical implant housing. For example: Exact orienting of miniature components to each other is needed before assembly or the sophisticated dispensing of adhesive material in microgram dosages or an alignment of delicate bayonet features is needed to combine a header with a housing. Furthermore, complicated injection molded parts with notches are needed for the fixation of the tines. Such manufacturing steps are hardly suitable for automatization, also since silicone adhesive manual cleaning procedures are needed after assembly.

Additionally, known headers take space from other critical components of the implantable intracardiac device, such as the battery or electronics module. Accordingly, smaller header size is desirable.

Furthermore, upon implantation of the intracardiac device, it may be desired to be able to reorient portions of the intracardiac device relative to its header assembly or particularly relative to the tines being fixed in heart tissue. Such re-orienting process may be required e.g. for establishing a desired communication orientation upon using coil induced electrical field communication. However, during operation of the intracardiac device, i.e. after having completed the implantation procedure, any unintended change in the orientation of the intracardiac device should be prevented.

In order to satisfy at least some of the mentioned requirements, a header assembly for an implantable intracardiac device and a respective intracardiac device have been presented in the applicant’s prior patent application PCT/EP2023/075727. At least some of the features and characteristics described in this prior application may be applied or adopted to the header assembly and the intracardiac device proposed in the present application and the content of the prior application shall be incorporated in its entirety herein by reference. There may be a need for implantable intracardiac devices and respective header assemblies addressing at least one of the above-mentioned requirements and furthermore enabling high reliability, long term service life and/or simple assembly. Particularly, there may be a need for a header assembly having small dimensions, providing a reliable mechanism for fixing the intracardiac device at heart tissue, enabling setting an orientation of the cardiac device during implantation and maintaining the orientation during subsequent device operation and/or enabling low manufacturing effort and costs.

Such need may be fulfilled by the subject matter of one of the independent claims. Advantageous embodiments are defined in the dependent claims, described in the present specification and visualised in the associated figures.

According to a first aspect of the present invention, a header assembly for an implantable intracardiac device is described. The header assembly comprises a cylindrical feedthrough arrangement, a ring-shaped proximal cap, a ring-shaped distal cap, a base ring with at least two tines protruding distally from the base ring, and a pressing arrangement. The feed- through arrangement has an outer shell surface. The proximal cap comprises an inner surface. The distal cap comprises an outer surface. The distal cap comprises a fixing portion with an inner surface. The inner surface forms a locking connection with the outer shell surface of the feedthrough arrangement for counteracting a movement of the distal cap and the feedthrough arrangement apart from each other in an axial direction. The proximal cap, the distal cap and the base ring are configured such that the inner surface of the proximal cap and the outer surface of the distal cap are arranged coaxially and directed towards each other, and the base ring is interposed between the inner surface of the proximal cap and the outer surface of the distal cap such as to be coaxially rotatable relative to the distal cap. The pressing arrangement is configured such as to exert an elastic force in a radial direction such as to press the base ring against one of the inner surface of the proximal cap and the outer surface of the distal cap. The proximal cap is made with a first material and the distal cap is made with a second material, the first material being softer than the second material. According to a second aspect of the present invention, an implantable intracardiac device is described, the device having a cylindrical housing and a header assembly realized as described herein, wherein the feedthrough is accommodated at the distal end of the housing, wherein the feedthrough is integrally formed with the housing or is formed by a separate element which is fixed and hermetically sealed at the distal end face of the housing, for example by welding.

Only as some introductory or summarising notes and without limiting the scope of the invention, basic ideas underlying embodiments of the invention and associated possible advantages may be roughly described as follows:

The header assembly presented herein is specifically configured for enabling a simple but nevertheless reliable assembling procedure upon mounting the header assembly to a housing of an implantable intracardiac device (hereinafter: “ID”). Particularly, the ring-shaped proximal and distal caps may be easily pressed in an axial direction onto the cylindrical feed- through arrangement provided at a distal end of the housing of the ID. Therein, the outer shell surface of the feedthrough arrangement and the inner surface of the fixing portion of the distal cap are specifically configured such that, upon being actually pressed together, a preferably non-reversible, i.e. permanent, locking connection such as a snap-fit connection or a press-fit connection is established between both components. Due to such locking connection, the header assembly is reliably held at the housing of the ID.

Furthermore, the base ring with its at least two tines is interposed between the inner surface of the proximal cap and the outer surface of the distal cap and is therefore also reliably held at the housing of the ID. Specifically, the base ring is arranged and configured such as to being coaxially rotatable relative to the distal cap. As the distal cap is fixed via the feed- through arrangement to the housing of the ID, the base ring is therefore rotatable with respect to the housing. On the one hand, such rotation capability may be used during an implantation procedure to correctly orientate the housing with respect to the tines extending from the base ring, these tines being fixed to cardiac tissue in order to correctly hold the entire ID. However, on the other hand, it should be prevented that such initially correct orientation is subsequently modified during the normal operation of the ID (i.e. after completion of the implantation procedure) for example due to rotation forces acting onto the ID during normal heartbeat and/or during motions of the patient. Accordingly, on the one hand, the base ring with its tines should be prevented from rotating relative to the housing of the ID as long as only minor rotation forces act onto the housing, such minor rotation forces being lower than rotation forces typically being applied to the housing during normal operation. On the other hand, rotating the base ring relative to the housing of the ID should be enabled upon major rotation forces acting onto the housing, such major rotation forces being for example applied during an implantation procedure for specifically orienting the ID housing.

In order to establish such specific rotation capability, it was tested that the base ring is clamped by a clamping action between the proximal cap and the distal cap such that it may only be rotated upon rotation forces being applied such as to exceed friction forces between the base ring, on the one side, and the proximal and distal caps, on the other side, the friction forces resulting from the clamping action. However, it has been observed that, in order to establish such clamping action, the distal cap would generally have to be mounted with its fixing portion on the feedthrough arrangement in a configuration in which substantial permanent mechanical stress is applied to the distal cap and its fixing portion. Although such distal cap is preferably being made from a high quality polymeric material such as PEEK, it has been observed that such permanent mechanical stress may result in mechanical failures or damages of the material of the distal cap, such effects also being referred to as environmental stress cracking (ESC). Particularly, such ESC preferably occurs upon polymeric components of the header assembly being loaded under a certain amount of mechanical stress (static or cyclic) and are exposed to an oxidative environment, such as a contact with human blood. However, any ESC occurring at the fixing portion of the distal cap might result in failure of the locking connection between such fixing portion and the outer shell surface of the feedthrough arrangement. Upon such failure, in a worst-case, the distal cap could detach from the feedthrough arrangement thereby releasing the entire fixation of the ID housing to the base ring and the tines fixed to the cardiac tissue. Of course such releasing action shall be prevented.

In order to suppress such occurrence of ESC, the distal cap may be adapted such that its fixing portion may be pushed onto the feedthrough arrangement during an assembling pro- cedure and may then form a locking connection in which the fixing portion is not permanently mechanically stressed beyond a degree at which ESC typically occurs. Furthermore, in order to ensure that a sufficient rotation friction is established between the proximal and distal caps and the base ring interposed between those, the header assembly furthermore comprises a specific pressing arrangement. Such pressing arrangement is configured such that an elastic force is exerted onto the base ring, thereby pressing the base ring against the proximal and/or the distal cap such as to finally establish the required rotation friction.

Furthermore, by suitably selecting the materials of the distal cap, the proximal cap and the pressing arrangement, elastic deformability of the respective components and, as a result thereof, pressure and friction between the components comprised in the fully mounted header assembly may be adjusted such that sufficient friction against rotatory motions (to prevent rotary motions below a certain level) of the components relative to each other may be induced while, on the other hand, excessive forces between the components may be prevented, thereby reducing risks for mechanical wear or even failures. Particularly, it has been found to be beneficial to provide the proximal cap with a first material being softer, i.e. more pliant, than a second material used for the distal cap. Thereby, the distal cap may be firmly held with its fixing portion at the feedthrough arrangement while establishing a relatively soft and deformable pressing connection between the base ring and the adjacent distal and proximal caps sandwiching the base ring. The difference in the softness of the materials of the distal and the proximal header cap seems to lead to the right amount of friction between the base ring and the corresponding caps to lower the mechanical stress on the base ring and the at least two connected tines, which further reduces the risk of mechanical failure / breakage of the at least two tines at the connection to the base ring.

Accordingly, correctly orienting the ID housing during an implantation procedure may be possible by applying rotation forces exceeding the rotation friction induced by the pressing arrangement whereas unintended miss-orienting of the ID housing during later operation is prevented as generally no rotation forces exceeding the rotation friction are induced during such normal operation of the ID. Furthermore, even in cases where excessive mechanical stress acts onto the pressing arrangement and therefore damages such as cracks eventually occur at the pressing arrangement for example due to ESC, such damages or cracks would only affect the pressing arrangement but not the rest of the header assembly and particularly not the fixing portion of the distal cap. Accordingly, even in case of such damages or cracks, an integrity of the entire header assembly and particularly a fixation of the distal to the feed- through arrangement are not jeopardized.

Subsequently, possible features of embodiments of the invention and associated possible advantages will be described in more detail.

The implantable intracardiac device may be, for example, an implantable intracardiac pacemaker (also known as leadless pacemaker) which may 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. In the last case, the ID may be called defibrillator or cardioverter, instead. Alternative or additional functions of intracardiac devices may 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. In case, the ID is focused on sensing electrical or electromagnetic signals it may be alternatively called (bio)monitor. The ID may contain any combination of above functions. The implantation of the ID may comprise any fixation to the heart's tissue comprising the fixing within the atria and the ventricles of the heart or a fixing at the outer surface of the heart's tissue using small tines.

The inventive header assembly is suitable for an ID which usually comprises a cylindrical housing and the header assembly located at the distal end of the housing. Further, a pinshaped electrode projects from the distal end of the housing, wherein the header assembly is arranged at and attached to the distal end of the housing of the ID such that the electrode projects through the header assembly, i.e. through a respective through-going or complete opening of the header assembly. The opening may be a central opening located at and along a longitudinal axis of the ID housing and the header assembly. The longitudinal axis forms the axial direction of the ID and the header assembly. The proximal cap, the base ring and the distal cap comprise the through-going opening, as well, wherein the size of the opening of the proximal cap may be such that an electrode feedthrough located at the proximal end of the electrode may be at least partly arranged within this opening. The cylindrical housing comprises the electronics module having a processor, an energy source (e.g. a battery or coil (for wireless charging)) and, if applicable, a communication component such as an antenna. The processor may be adapted to process signals/data determined from the patient's body or received from the surrounding environment and/or to produce signals for treatment of the patient's heart. Such signals may comprise electrical stimulation in the form of pulses in order to generate a physiologically appropriate heartrate, shocks for cardioversion or defibrillation in order to restore a more normal heart rhythm and/or other electrical or electromagnetic signals to the heart or its surrounding tissue. Such signals are transformed and transmitted by the electronic module and may be applied by the pin-shaped electrode to the heart or its surrounding tissue. The pin-shaped electrode is electrically connected to the electronics module and the energy source. The hermetically sealed housing may comprise electrically conducting material, e.g. titanium or stainless steel, and may function as another electrode. The header assembly comprises elements (the tines) for fixation of the ID to the selected tissue of the patient according to a treatment plan of a heath care provider (HCP), for example a ventricular wall of the patient's heart. Further, the header assembly provides electrical isolation of the pin-shaped electrode with regard to the tines and/or the ID housing. The cylindrical feedthrough provides a seat for the pin-shaped electrode and electrical isolation of it with regard to the housing. The electrical isolation is particularly caused by the distal cap and the proximal cap, wherein the distal cap and the proximal cap comprise electrically isolating material, wherein the base ring is accommodated between the proximal cap and the distal cap in axial direction. The base ring carries at least two tines, for example two tines, four tines or six tines, protruding in distal direction from the base ring which provide fixation of the ID within the tissue of the patient at the desired treatment location after implantation. Therefore the tines are anchoring within the tissue.

For accommodation of the feedthrough and the electrode, the proximal cap, base ring and distal cap are all basically and/or essentially ring-shaped and accommodated in this consecutive order from proximal to distal direction along an axial direction, wherein the feed- through and the pin-shaped electrode are located within the inner opening of the respective ring after completion of the manufacturing. Such uniaxial stackable assembly configuration from all rotational symmetrical components is advantageous because these components can be manufactured easily and at low cost. Further, they allow uniaxial assembly which is automated production friendly. The inventive header assembly construction as indicated above and below further avoids notches in the isolating components (distal cap and proximal cap) which reduces the complexity of the header assembly components as they are symmetrical, turned components having a longitudinal axis which also represents the axial direction.

The cylindrical feedthrough comprises an outer shell surface at least at its distal end. Further, the cylindrical feedthrough forms a distal end face. The distal end of the cylindrical feed- through forming the outer shell surface is regarded a component of the header assembly.

After completion of the ID production and fixing of the header assembly to its end face the ring-shaped distal cap forms a permanent connection which counteracts a movement of the distal cap and the feedthrough apart from each other in distal direction. The connection is provided by a surface structure which is provided at the inner surface of a through hole of the distal cap and/or the outer shell surface of the feedthrough. According to the invention, the inner surface of the distal cap forms a locking connection with the outer shell surface of the feedthrough.

For example the distal cap may comprise a structure at the inner surface of its fixing portion which is configured for establishing a snap-fit locking connection with the outer shell surface of the feedthrough arrangement. In other words, the fixing portion of the distal cap and the feedthrough arrangement may be adapted at their opposing surfaces such that, during assembling both components by pushing the distal cap axially onto the feedthrough arrangement, at least one of both components is temporarily deformed until reaching a position at which a snap-fit locking connection is established between both components. In such snap-fit locking connection, both components may engage at their opposing surfaces in a form-fit fashion. Therein, the opposing surfaces are in form-fit engagement without substantially permanently deforming one of the components, i.e. without substantial forces being exerted in a radial direction onto at least one of the fixing portion of the distal cap and the feedthrough arrangement. More specifically, the outer shell surface of the feedthrough arrangement and the inner surface of the fixing portion of the distal cap may have surface structures with protrusions and recesses being at least partially complementary to each other such as to establish a snap-fit locking connection between the outer shell surface and the inner surface. Thus, protrusions at the surface of one of the inner surface of the fixing portion of the distal cap and the outer shell surface of the feedthrough arrangement may engage into recesses at an opposing surface of the other component in a snap-fit manner.

Alternatively, the fixing portion of the distal cap may be configured for establishing a press- fit locking connection with the outer shell surface of the feedthrough arrangement. Similarly to the above described establishing of the snap-fit connection, the fixing portion of the distal cap and the feedthrough arrangement may be pushed together in an axial direction and may slide onto each other while being temporarily slightly radially deformed. Upon reaching a final position, the radial deformation may be partly released. However, a rest of such elastic deformation may remain and may result in a radial pressure being exerted between the inner surface of the fixing portion and the outer shell surface of the feedthrough arrangements. Due to such radial pressure, some permanent deformation may be induced in at least one of these surfaces. Accordingly, in such press-fit locking connection, substantive actual pressures may act between the connected components and, additionally, preconfigured surface structures and/or induced deformations at the opposed surfaces of the components may engage in a form-fit fashion.

More specifically, the outer shell surface of the feedthrough arrangement and the inner surface of the fixing portion of the distal cap may have surface structures being at least partially non-complementary to each other such as to establish a press-fit locking connection between the outer shell surface and the inner surface. In other words, at least before being engaged, the inner surface of the fixing portion and the opposing outer shell surface of the feedthrough arrangement may both have protruding and/or recessed structures which, however, are not complementary to each other. Accordingly, upon being assembled, those opposing surfaces may not completely engage with each other without radial forces being locally induced at portions of the engaged surfaces which are non-complementary to each other. These radial forces and/or resulting permanent deformations at the engaged surfaces are typical for the press-fit locking connection.

Accordingly, the inner surface of the distal cap and the outer shell surface of the feedthrough may comprise a first surface structure adapted to provide a form locking connection with the respective other surface when the distal cap is attached to the feedthrough, wherein the form locking connection may comprise force locking, as well. The other surface is the inner surface of the distal cap or the other shell surface of the feedthrough. After assembly/fixing the feedthrough and the distal cap are permanently connected by a press-fit connection or snap- fit connection at their adjoining surfaces so that they cannot move relative to each other. The first surface structure of the outer shell surface of the feedthrough and/or of the inner surface of the distal cap or of both interact and engage and/or interlock with each other to form the press-fit or snap-fit connection. The first surface structure may comprise protrusions, for example extending in radial direction and forming an undercut, e.g. saw-tooth protrusions, a threaded structure, or may comprise a bayonet joint. A relative movement of the distal cap and the feedthrough is not possible in the fixed state (i.e. the fully assembled state), therefore also not a movement apart from each other in axial direction. Hence, gluing is avoided. Further, the production may use simple movement and forces directed in axial direction thereby avoiding more complicated rotational assembly movements.

The ring-shaped proximal cap is adapted to be fit into and along a respective circular recess of the distal end face of the ID housing in order to provide easy, exact and fast positioning during production. For that, the proximal cap may form a cylindrical protruding rim at its proximal surface.

Additionally, another form locking connection is provided for fixing the base ring between the distal cap and the proximal cap. This form locking connection is further described below.

The distal cap may comprise a stopper face at a distal section of its inner surface. The stopper face may be formed by a proximal surface of a protrusion projecting in radial direction from the inner surface of the distal cap, wherein the radial direction runs radially from the central longitudinal axis of the ID or its header assembly. The protrusion may be located at the most distal section of the inner surface of the distal cap. The stopper face interacts with the distal end face of the distal section of the feedthrough and forms a mechanical stop during assembling of the header assembly and the ID. The stopper face stops the press-fitting or snapfitting movement of the distal cap or the ID housing at the correct position and thereby improves production quality. It further avoids mechanical damage of one of the press-fitted or snap-fitted components since it avoids mechanical overload by limiting the distance of movement of the components during press-fitting or snap-fitting.

An inner surface of the proximal cap formed by a through hole of the proximal cap may comprise a second surface structure and/or may form a form locking connection with the outer shell surface of the feedthrough when the proximal cap is attached to the feedthrough. In the same way as the distal cap the proximal cap may as well form a permanent press-fit or snap-fit, form locking connection with the outer shell surface of the feedthrough after completion of assembly. The forces acting in this essentially form locking connection may comprise force locking, too. The surface structure of the outer shell surface of the feed- through or of the inner surface of the proximal cap or of both may interact and engage and/or interlock in the same manner as the distal cap and the feedthrough. Thereby gluing is avoided, as well, and production efficiency is enhanced.

The first surface structure and/or second surface structure may comprise at least two protrusions, wherein the at least two protrusions are accommodated in an axial direction one above the other and/or in circumferential direction next to each other, and/or a threaded profile. Preferably, the first surface structure and/or the second surface structure comprise a plurality of such protrusions accommodated one above the other or next to each other as described above. All protrusions project at least partially in radial direction from the surface forming the first or second surface structure, i.e. from the inner surface of the distal cap, from the inner surface of the proximal cap and/or from the outer shell surface of the feedthrough. Dimension of the protrusions in radial direction (perpendicular to the axial direction) may be less than 200 pm, preferably less than 150 pm (for example for a surface structure at the outer shell surface) in order to reliably fix the distal cap to the feedthrough. It may be greater than 50 pm. It was calculated by FEA that these dimensions of protrusions widen the distal cap diameter in such a way that the strain in the distal cap material (e.g. PEEK) reaches 50 % - 95 % of its tensile strength (which is ca. 100 MPa at maximum). The inner surface of the distal cap and/or the inner surface of the proximal cap may comprise a threaded profile (female thread) and the outer shell surface may comprise a threaded profile (male thread) which is engaged in order to fix the distal cap and/or the proximal cap to the feedthrough. In one embodiment, the opposite threaded profiles form a self-locking thread.

The at least two protrusions may extend along at least part of the outer circumference of the outer shell surface of the feedthrough or extend along at least part of the inner circumference of the inner surface of the distal cap or of the inner surface of the proximal cap. This means that the at least two protrusions have a pre-defined length along the outer circumference or along the inner circumference. They may extend along 1/4 of the respective circumference, along 1/2 of the respective circumference or along full circumference or even longer. The at least two protrusions may extend inclined with regard to the axial direction or perpendicular to this direction. The at least two protrusions may be distributed at the inner surface of the distal cap or the proximal cap or at the outer shell surface of the feedthrough or their length may be adapted such that the forces deriving from the press-fitting or snap-fitting of the feedthrough and the distal cap or the proximal cap, respectively, are well distributed across these surfaces in order to avoid stress peaks.

In one implementation, the respective other surface comprises at least one indentation for receiving the at least two protrusions when the distal cap or the proximal cap is attached to the feedthrough. For example, the outer surface of the feedthrough comprises at least two protrusions and the inner surface of the distal cap comprises at least one indentation which may mirror the at least two protrusions so that they perfectly interlock with each other after completion of assembling. The fixing may also be described as a snap-in step. For example, the inner surface of the distal cap may comprise a circular groove extending around the full circumference of the inner surface. In another embodiment the at least two pin-shaped protrusions extending from the outer shell surface of the feedthrough and L-shaped indentations of the inner surface of the distal cap form a bayonet connection. Having an indentation at the other surface reduces the strain in the distal cap or the proximal cap material, for example polymer material, thereby mitigating potential material breakages caused by high strain. In one implementation, at least part of the at least two protrusions have a saw-tooth shape, for example, the at least two protrusions form at least two saw-tooth shaped circular rims accommodated one over the other in axial direction and extend along the full circumference or along part of the circumference, wherein the inclined surface of the saw-tooth shape has an angle, for example a small angle, e.g. with a value of more than or equal to 45°, preferably more than or equal to 60° but less than 90° with regard to the radial direction. With its angled shape the saw-tooth shaped protrusions ease the assembly by this slide-in chamfers. On the contrary the saw-tooth shaped rim with its second angle between 110° and 70°, preferably between 100° and 80°, with regard to the axial direction enclosed by the surfaces of each protrusion which project from the outer shell surface of the feedthrough, “bites” into the distal cap inner surface and prevents the distal cap from becoming loose. A permanent fixation is thereby established. Alternatively or additionally, the at least two protrusions may form barbs at their furthest outwardly protruding end in order to further enhance their retention properties.

In one implementation, the outer rim of the protrusions may have a circular cross section. In another implementation the cross section of the outer rim of the protrusions may have a rounded polygonar form, e.g. a trilobular form. This gives the polymer distal cap space for inside deforming, reduces the stress to the distal cap and prevents it from breakage. Further, this solution is less prone to manufacturing tolerances because a wider range of cap inside diameters fits without breakage and/or may have self-locking behaviour.

In the header assembly presented herein, the proximal cap and the distal cap shall be made with, i.e. shall comprise or consist of, different materials. Specifically, the proximal cap shall be made with a first material which is softer than a second material used for making the distal cap. In this context, “softer” may mean more easily deformable or being more pliant. In other words, while the distal cap shall be made with a relatively rigid material in order to stably engage and mechanically interact with the feedthrough arrangement, the proximal cap may be made with a softer material such that, inter-alia, excessive local forces onto the base ring being sandwiched between the distal cap and the proximal cap may be avoided and, instead, forces acting onto such base ring due to for example tines extending from the base ring being temporarily deformed may be at least partially absorbed by deformation of the soft proximal cap.

Particularly, according to an embodiment, the first material may have a Shore A hardness of between 10 and 100, preferably between 30 and 60.

In other words, the proximal cap may be made with a soft first material in a durometer range of Shore A between 10 and 100, in particular between Shore A 30 and 60. Therein, durometer, or hardness, is a material property that describes a material’s tendency to resist localized deformation or indentation. The Shore A hardness (durometer) scale is one of many durometer scales used to measure material hardness. Shore A durometers range from 0 to 100 — the higher the durometer value, the harder the material. The Shore A scale is often used in the polymer industry to aid in material selection, ensure consistent quality products, and easily compare the hardness of materials. There are several scales of durometer, used for materials with different properties. The two most common scales, using slightly different measurement systems, are the ASTM D2240 type A and type D scales. The Shore A durometer scale is commonly used for soft to medium-soft materials such as vulcanized and natural rubber, TPEs (thermoplastic elastomers), flexible polyacrylics and thermosets, leathers, wax, and felt, while the D scale is for harder materials.

According to a specific embodiment, the first material is liquid silicone rubber.

Other materials having a Shore A value as mentioned above like thermoplastic elastomers, polyurethane or other flexible polymers may be suitable as well.

A Liquid Silicone Rubber (LSR) process is a method for manufacturing moulded parts from silicone rubber by injection moulding or 3D printing from liquid or low- viscosity two-component components. Products made from LSR may be used in a wide range of applications thanks to their universal material properties. Typical components of LSR silicone rubber are linear siloxanes (approx. 70 %), fillers (approx. 30 %) and additives (approx. 1 %). There are various specific types of LSRs, wherein physical characteristics of the LSR material may be influenced by an amount and/or type of chemical components comprised therein. Accordingly, the LSR material used for the proximal cap may be specifically adapted for its application in the header assembly both with regards to its physical characteristics as well as its chemical characteristics, thereby enabling, inter-alia, a desired soft deformability as well as sufficient chemical resistance against a harsh chemical environment in cardiac applications.

According to an embodiment, the second material is poly etheretherketone.

In other words, the distal cap may be made with PEEK as a relatively rigid and highly mechanically loadable polymeric material. Therein, the use of PEEK may allow for a suitable mechanical stiffness and stability of the distal cap, thereby ensuring stable and safe attachment of the entire header assembly to a housing of an implantable intracardiac device and its feedthrough arrangement.

In the following, some possible characteristics and advantages of the pressing arrangement of embodiments of the header assembly are described.

The pressing arrangement may have a higher deformability in and against the radial direction than the fixing portion of the distal cap. Thus, upon radial forces being exerted between the base ring, on the one side, and the distal cap, on the other side, these forces also act onto the pressing arrangement. As the pressing arrangement has a higher deformability than the fixing portion of the distal cap, a smaller deformation is induced in the fixing portion as compared to the pressing arrangement as a result of such radial forces. Accordingly, any risk of environmental stress cracking is reduced in the fixing portion of the distal cap. As a result, a reliability of the distal cap’s fixation to the feedthrough arrangement may be increased.

According to an embodiment, the pressing arrangement is made with a third material being softer than the second material.

In other words, the pressing arrangement is preferably made with a softer material than the distal cap. Accordingly, as the pressing arrangement is configured to exert an elastic force in a radial direction such as to press the base ring with an elastic force against the inner surface of the proximal cap or against the outer surface of the distal cap, such forces may generally be generated or absorbed, respectively, upon elastic deformation of the soft third material of the pressing arrangement. In other words, pressing arrangement may provide a soft buffer material between the tine base ring and the distal cap hard material.

According to an embodiment, the third material has a Shore A hardness of between 10 and 100, preferably between 30 and 60.

Particularly, according to an embodiment, the third material is liquid silicone rubber.

Thus, the third material of the pressing arrangement may have similar or same characteristics as the first material of the proximal cap.

Possibly, according to an embodiment, the first material and the third material are identical. I.e, both components may consist e.g. of LSR.

Furthermore, according to an embodiment, the pressing arrangement comprises an O-ring.

In other words, the pressing arrangement may include or consist of a closed ring having a round or cylindrical O-form. Particularly, in a top view, such O-ring may have a circular, oval or elliptical shape. Furthermore, in a cross-sectional view, the O-ring may have a circular or elongate shape. Other non-standard shapes, in particular a shape conformal to the angle of the base ring, may be suitable as well.

For example, according to an embodiment, the pressing arrangement is provided as an individual component being separable from the distal cap.

Expressed differently, the pressing arrangement may be a component on its own which may be fabricated independently from the distal cap and/or from other components of the header assembly and which may be mounted to the header assembly upon assembling the entire header assembly. Accordingly, characteristics of the pressing arrangement such as its shape, dimensions, material, etc. may be selected or designed independently from those of other components of the header assembly and may be specifically adapted to fulfil intended functions of the pressing arrangement.

Alternatively, according to an embodiment, the pressing arrangement is provided as a fixed component attached to the distal cap.

In other words, the pressing arrangement and the distal cap may be fixedly attached to each other. Accordingly, both components may form a unit which may be easily handled and/or mounted to the header assembly.

Specifically, according to an embodiment, the pressing arrangement is attached to the distal cap by an overmoulding portion being integral with the distal cap and at least partly enclosing the pressing arrangement.

In such implementation, the distal cap may be formed by a moulding procedure such as e.g. injection moulding. Therein, further to forming a core of the distal cap, the moulding procedure may be applied for additionally forming an overmoulding portion which extends from such core in a direction towards the pressing arrangement and which is at least partly enclosing a component such as an O-ring forming the pressing arrangement. In such approach, the pressing arrangement and the distal cap together with its overmoulding portion form a unitary part which may be easily handled as a single unit and which may be produced in a simple moulding procedure.

According to an embodiment, the pressing arrangement has a cross-sectional thickness of between 0.2 mm and 1 mm, preferably between 0.3 mm and 0.7 mm.

In other words, a dimension of the pressing arrangement in the thickness direction may be relatively small, i.e. smaller than 1 mm, such as to enable keeping the entire header assembly small, but may be large enough, i.e. larger than 0.2 mm, such as to enable sufficient elastic deformation of the pressing arrangement in order to enable absorption of deflections or deformations of the base ring relative to the distal cap and/or relative to the proximal cap, respectively. Particularly, in case of the pressing arrangement being implemented as an O- ring having a circular cross-section, the cross-section thickness may correspond to a diameter of such cross-section. Alternatively, if the pressing arrangement is implemented with e.g. an elongate cross-section, the cross-sectional thickness may correspond to a dimension of such pressing arrangement in a radial direction.

In the following, some further possible characteristics and advantages of the header assembly are described.

In one implementation, the inner surface of the distal cap is inclined or tapered, wherein an inner diameter of a most proximal section is greater than an inner diameter of a section distally from the most proximal section. Alternatively, an inner diameter of a most proximal section is smaller than an inner diameter of a section distally from the most proximal section. If there are protrusions at the inner surface of the distal cap or at the outer shell surface of the feedthrough, their inner or outer diameter may increase or decrease along axial direction, accordingly. If the inner diameter of the surface or the protrusions increases in proximal direction along axial direction the retention force of the connection of the distal cap and the feedthrough increases. However, the stress to the material of the distal cap increases, too.

In one implementation, the distal cap and the proximal cap comprise electrically isolating material and the distal cap and/or the proximal cap additionally may comprise elastic material. The distal cap may e.g. comprise or may fully be composed of polyether ether ketone (PEEK), liquid crystal polymer (LCP), polysulfone (PSU) or other polymer material with similar properties. The proximal cap may e.g. comprise or may fully be composed of liquid silicone rubber (LSR) or other polymer material with similar properties. The elasticity of the above materials is advantageous for the manufacturing process as it helps to establish the press-fitting connection.

In one implementation, the header assembly may comprise a ring shaped steroid depot which is accommodated in axial direction between the distal cap and the distal end face of the feedthrough. The steroid depot contains at least one medical substance, for example an anticoagulant and/or an antibacterial substance. The medical substance may be released gradually into the blood close to the fixation location of the ID within the patient's tissue in order to heal the damaged tissue close to the fixation location. The steroid depot may be clamped between the stopper face of the distal cap and the distal end face of the feedthrough so that it is permanently fixed at the header assembly and the ID. Further, an inner rim protruding in distal direction may be located adjacent to a respective stopping face of the pin-shaped electrode located at the proximal end of the pin head. Thereby, the electrode keeps the steroid depot in place.

In one implementation, the form locking fixing of the base ring with the tines between the proximal and distal caps is provided by conically formed surfaces at the proximal and/or distal cap and a conical form of the base ring. The conical form of the base ring means that the inner and the outer surface of the ring have a conical, inclined form, wherein both surfaces run essentially parallel. In particular, the conical form of the base ring means that the inner diameter and the outer diameter of the base ring is greater at its distal end than the respective diameter at its proximal end. If both sides of the base ring run parallel, the wall thickness of the base ring is constant along its entire axial length. In another embodiment, its wall thickness may change along its length (i.e. become thinner or thicker along the axial direction and into distal direction). The base ring with the at least one tine is clamped and fixed between the proximal cap (on its proximal side) and the distal cap (on its distal side). For that a side face (distal face) of the proximal cap adjacent the base ring and a side face (proximal face) of the distal cap adjacent the base ring have the same inclination or slope as the respective lateral surface of the base ring. This optimizes space and results in fewer header components causing less processing and assembly steps with less costs during manufacturing of the ID. The axial length and volume of the header is minimized. This improvement allows more space for other more critical features of the device, such as the battery, which would increase device longevity. The base ring is conically shaped to allow for axial height reduction while maintaining band height. In other words, the space could be allotted to the electronics module, to incorporate more therapeutic features. Conversely, for the same battery and electronics module size, a reduction in header length would allow for a reduction in overall device length. This enables application for smaller patients, or alternate placement within the heart, such as the right atrium. In one implementation, each of the at least two tines comprises an abutting section directly extending from the base ring and forming a connection with the base ring and a flex zone, wherein the abutting section of the respective tine continues the conical form of the base ring. Each of the plurality of tines terminates into the base ring tangent to the arc of the tines just below the surface of the distal cap and the base ring is contained fully by the distal cap at its distal side and by the proximal cap at its proximal side. The middle section of each tine of the plurality of tines has a curved form (e.g. circular curved) and the end section furthest from the base ring comprises a straight section. Other forms of each tine are possible, as well. In one embodiment the base ring and the at least one tine are integrally formed. The base ring and/or the at least two tines may partially or fully consist of biocompatible material, e.g. shape memory material, for example Nitinol.

As described herein, the fixing of the essential header components may be provided by a method not using adhesive bonding forces but using the elastic and plastic material properties of the polymer (e.g. thermoplastic) distal cap to achieve a reliable long term stable connection to the ID housing. Stretching the diameter of the distal cap to a certain degree that it does not break in combination with the surface structure (e.g. at the feedthrough outer shell surface) proves this snap-fit or press-fit connection as permanent attachment.

It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teaching. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention.

The present invention will now be described in further detail with reference to the accompanying schematic drawings, wherein

Fig. 1 shows an embodiment of an inventive implantable ID with an inventive header assembly in a longitudinal-sectional, exploded and perspective view, Fig. 2 shows an embodiment of an inventive header assembly in an exploded side view,

Fig. 3 shows the header assembly of Fig. 2 in an assembled side view,

Fig. 4 shows the header assembly of Fig. 2 in a cross-sectional view,

Fig. 5 shows an alternative embodiment of the inventive header assembly with a distal cap with an integrated pressing portion in a cross-sectional view.

The figures are only schematic representations and not necessarily to scale. Throughout the figures, same reference signs indicate same or similar features.

Fig. 1 illustrates an exploded view of components of an embodiment of an implantable ID 1, e.g. a leadless pacemaker, with a header assembly 3.

The components are a ring-shaped distal cap 9, a base ring assembly 12 comprising a base ring 11 and four tines 13, a washer-like steroid depot 39, a ring-shaped proximal cap 7, an O-ring 31 forming a pressing arrangement 15 and an ID housing 35 comprising a cylindrical distal section forming a feedthrough 5 and a pin-shaped electrode 41 extending therefrom in distal direction. The base ring 11 is conically formed in such way that a distal end of the base ring 11 has a greater inner and outer diameter compared with these diameters at its proximal end.

The distal cap 9, the base ring 11, the steroid depot 39 and the proximal cap 7 - each of these components comprises a central through-going opening for accommodation of the electrode 41. The components referred to in the previous sentence are axially symmetrical with regard to the longitudinal axial centre axis defining the axial direction 27. The diameter of the central opening of the distal cap 9, the base ring 11 and the proximal cap 7 is such that the electrode feedthrough 41 is located within this opening in a fixed/assembled state. The diameter of the electrode feedthrough 5 is greater than the diameter of the electrode 41. The ring-shaped distal cap 9 comprises the through-going opening forming an inner surface 25 at a fixing portion 23. At a distal end of this opening, a rim-shaped protrusion 43 is provided extending in radial direction 29 from the inner surface 25 and forming a circular stopper face 45. Further, the distal cap 1 comprises an outer surface 21 to which the O-ring 31 of the pressing arrangement 15 abuts in the assembled state. The distal cap 9 consists of electrically isolating and elastic material, for example PEEK.

The four tines 13 extend from the conical shaped base ring 11, wherein each tine 13 has an abutting section (flex zone) which transitions to the base ring 11, a curved middle section and a straight end section (furthest from the base ring 11). The tines 13 provide the mechanical fixation of the ID within the patient's heart after deployment and penetration of the heart's tissue such that the central electrode 41 is in mechanical and electrical contact with the inner tissue of the patient's heart within one ventricle or atrium. The proximal cap 7 ensures electric isolation of the tines 13 from the housing 35. The base ring assembly 12 and the tines 13 consists of Nitinol, for example.

The header assembly 3 comprises the pressing arrangement 15. The pressing arrangement 15 comprises the O-ring 31 being interposed between the outer surface 21 of the distal cap 9 and the base ring 11 of the base ring assembly 12. The pressing arrangement 15 has a higher deformability in and against a radial direction 29 perpendicular to the axial direction 27 than the fixing portion 23 of the distal cap 9.

Having such specific configuration, the pressing arrangement 15 is configured to exert an elastic force in a radial direction 29, i.e. orthogonal to the axial centre axis in the axial direction 27, such as to press the base ring 11 against the inner surface 19 of the proximal cap 7, upon the base ring 11 being interposed between the proximal cap 7 and the distal cap 9. Accordingly, in such assembled configuration, the pressing arrangement 15 induces friction forces acting onto the base ring 11 upon the base ring 11 being rotated around the axial direction 27 relative to the caps 7, 9. Due to its high local deformability, the pressing arrangement 15 may be deflected upon assembling the header assembly 3 and, as a result of such elastic deflection, the pressing arrangement 15 may then reliably press the base ring 11 against the inner surface 19 of the proximal cap 7 while the fixing portion 23 of the distal cap 9 is not significantly deformed.

Accordingly, even in an assembled state with the base ring 11 being compressed between the distal cap 9 and the proximal cap 7, no significant permanent mechanical stresses are exerted onto the inner surface 25 and particularly the fixing portion 23 of the distal cap 9. Accordingly, a risk of any environmental stress cracking (ESC) occurring at the fixing portion 23 of the distal cap 9 may be minimized. Thus, a locking connection formed between the outer shell surface 17 of the feedthrough arrangement 5 and the inner surface 25 of the distal cap 9 as described further below is not compromised due to ESC. Instead, permanent mechanical stress is only applied at the pressing arrangement 15. However, even in cases where such stress results in ESC at the pressing arrangement 15, the mechanical connection between the header assembly 3 and the housing 35 of the intracardiac device 1 is still reliably maintained.

There is the washer-like steroid depot 39 comprising a through hole 47. The steroid depot 39 is made of a mixture of silicone and dexamethasone acetate. The inner section of the steroid depot 39 is slightly arched upwardly into distal direction forming a distally projecting rim 49 to which a stopper face 51 of an electrode head 53 abuts.

The header assembly and the ID further comprise the proximal cap 7 forming an inclined inner surface 19 at its distal side. If one views the proximal cap 7 from the proximal direction the proximal cap comprises a circular stop surface 55 for abutting a rim 57 at the distal end face 37 of the housing 5. The circular rim 57 together with a circular recess adjacent to the distal end face 37 surrounding the feedthrough 5 cause centering of the proximal cap 7 and the distal cap 9.

The proximal cap 7 consists of electrically isolating and elastic material being softer than the material of the distal cap 9. For example, the proximal cap 7 may consist of liquid silicone rubber. Due to its soft and deformable material, the proximal cap 7 may easily elastically deform and/or displace upon pressures being exerted from the base ring 11 towards the proximal cap 7. Accordingly, no local excessive pressures are generated and applied either to the base ring assembly 12 or to the distal cap 9, thereby preventing damage to these components.

As indicated above, the ID housing 35 forms the feedthrough arrangement 5 at its distal end. In the depicted embodiment, the feedthrough arrangement 5 is integrally formed with the housing 35 but may alternatively be formed as a separate element which is hermetically sealed attached to the housing 35. The feedthrough arrangement 5 forms an outer shell surface 17 with surface structures having a plurality of saw-tooth protrusions.

The housing 35 of the intracardiac device 1 contains in its inner volume 59 a battery and an electronic module comprising a processor (not shown) and ensures hermetically sealing of these components. These components are electrically connected to the electrode 41 and provide the electrical stimulation of the heart or processing of electrical signals determined from the heart. Further, the housing may contain components for communication such as an antenna. The housing may consist of a titanium alloy or stainless steel.

Figs. 2 - 5 show alternative and partially simplified embodiments of the header assembly 3. Therein, many structural characteristics and/or functional characteristics are identical or similar to those of the embodiment described above.

Particularly, the distal cap 9 is made with relatively rigid material such as PEEK whereas the proximal cap 7 and the O-ring 31 forming the pressing arrangement 15 are made with softer materials such as LSR.

As the base ring assembly 12 is interposed with its base ring 11 between the proximal cap 7 and the pressing arrangement 15, forces acting onto the base ring assembly 12 as a result of the distal cap 9 engaging with the feedthrough arrangement 5 at the housing 35 of the intracardiac device 1 may be limited to an extend in which substantial mechanical wear or even damages may be avoided. As visualised in Fig. 4, the entire header assembly has a height Hl extending from a lower end of the proximal cap 7 to an upper end of the distal cap 9, such height Hl typically being in a range of between 1 mm and 2.5 mm, in most cases between 1.5 mm and 2 mm. A curvature radius R at an upper circumferential edge of the distal cap 9 may be in a range of between 0.2 mm and 1 mm, preferably between 0.4 mm and 0.6 mm. An overall height H2 of the distal cap 9 is typically between 0 mm and 0.5 mm smaller than the height Hl. An overall height H3 of the proximal cap 7 is typically in a range of between 0.5 mm and 1 ,6mm, in many cases between 0.9 mm and 1.1 mm. In the example shown, the O-ring 31 of the pressing arrangement 15 does not have a round cross section but an oval cross-section with a height H4 being substantially larger than a cross-sectional thickness Tl. For example, the height H4 may be in a range of between 0.5 mm and 1 mm, preferably between 0.7 mm and 0.8 mm, whereas the thickness Tl may be in a range of between 0.3 mm and 0.6 mm, preferably between 0.3 mm and 0.5 mm. Therein, the thickness Tl approximately corresponds to a distance in the radial direction 29 between the outer surface 21 of the distal cap 7 and an opposing inner surface of the base ring 11.

While, in the embodiment of Fig. 4, the pressing arrangement 15 is provided as an individual component 30 formed by the O-ring 31 such as to be separable from the distal cap 9, Fig. 5 visualises an alternative embodiment in which the O-ring 31 is fixedly attached to the distal cap 9 thereby forming a fixed component 32.

Specifically, an overmoulding portion 33 is provided at the distal cap 9 such as to enclose the O-ring 31 at least in partial regions thereof in a manner such as to permanently fix it to a core of the distal cap 9. Particularly, the overmoulding portion 33 is formed by protrusions which extend from the core of the distal cap 9 such as to overlap and engage with the O-ring 31. For example, such specific distal cap 9 and its overmoulding portion 33 may be formed by injection moulding or co-moulding in which the softer O-ring 31 is at least partly enclosed within harder material of the distal cap 9 while still remaining exposed at least at a partial surface thereof with which it may abut e.g. against the base ring 11.

Further details of possible implementations of the intracardiac device 1 and its header assembly 3 as well as of an exemplary procedure for manufacturing the ID 1 with its header assembly 3 are described in the applicant’s prior application as indicated in the introductory portion further above and may be adopted to the approach described herein.

List of reference signs

I implantable intracardiac device

3 header assembly

5 cylindrical feedthrough arrangement

7 proximal cap

9 distal cap

I I base ring

12 base ring assembly

13 tine

15 pressing arrangement

17 outer shell surface of feedthrough arrangement

19 inner surface of proximal cap

21 outer surface of distal cap

23 fixing portion of distal cap

25 inner surface of fixing portion

27 axial direction

29 radial direction

30 individual component

31 O-ring

32 fixed component

33 overmoulding portion

35 housing

37 distal end face

39 steroid depot

41 electrode

43 protrusion

45 stopper face

47 through hole

49 rim at steroid depot

51 stopper face

53 electrode head 55 stop surface

57 rim of housing

59 inner volume of housing Hl height of header assembly

H2 height of distal cap

H3 height of distal cap

H4 height of pressing arrangement

R radius of distal cap at upper outer edge T1 cross-sectional thickness of pressing arrangement

Claims

1. A header assembly (3) for an implantable intracardiac device (1), wherein the header assembly comprises: a cylindrical feedthrough arrangement (5), a ring-shaped proximal cap (7), a ring-shaped distal cap (9), a base ring (11) with at least two tines (13) protruding distally from the base ring, and a pressing arrangement (15), wherein the feedthrough arrangement (5) has an outer shell surface (17), wherein the proximal cap (7) comprises an inner surface (19), wherein the distal cap comprises (9) an outer surface (21), wherein the distal cap (9) comprises a fixing portion (23) with an inner surface (25), the inner surface (25) forming a locking connection with the outer shell surface (17) of the feedthrough arrangement (5) for counteracting a movement of the distal cap (9) and the feedthrough arrangement (5) apart from each other in an axial direction (27), wherein the proximal cap (7), the distal cap (9) and the base ring (11) are configured such that the inner surface (19) of the proximal cap (7) and the outer surface (21) of the distal cap (9) are arranged coaxially and directed towards each other, and the base ring (11) is interposed between the inner surface (19) of the proximal cap (7) and the outer surface (21) of the distal cap (9) such as to be coaxially rotatable relative to the distal cap (9), wherein the pressing arrangement (15) is configured such as to exert an elastic force in a radial direction (29) such as to press the base ring (1) against one of the inner surface (19) of the proximal cap (7) and the outer surface (21) of the distal cap (9), wherein the proximal cap (7) is made with a first material and the distal cap (9) is made with a second material, the first material being softer than the second material.

2. The header assembly according to claim 1, wherein the first material has a Shore A hardness of between 10 and 100.

3. The header assembly according to claim 1, wherein the first material is liquid silicone rubber.

4. The header assembly according to claim 1, wherein the second material is polyetheretherketone.

5. The header assembly according to claim 1, wherein the pressing arrangement (15) is made with a third material being softer than the second material.

6. The header assembly according to claim 5, wherein the third material has a Shore A hardness of between 10 and 100.

7. The header assembly according to claim 5, wherein the third material is liquid silicone rubber.

8. The header assembly according to claim 5, wherein the first material and the third material are identical.

9. The header assembly according to claim 1, wherein the pressing arrangement (15) comprises an O-ring (31).

10. The header assembly according to claim 1, wherein the pressing arrangement (15) is provided as an individual component (30) being separable from the distal cap (9).

11. The header assembly according to claim 1, wherein the pressing arrangement (15) is provided as a fixed component (32) attached to the distal cap (9).

12. The header assembly according to claim 11, wherein the pressing arrangement (15) is attached to the distal cap (9) by an overmoulding portion (33) being integral with the distal cap (9) and at least partly enclosing the pressing arrangement (15).

13. The header assembly according to claim 1, wherein the pressing arrangement (15) has a cross-sectional thickness (Tl) of between 0.2 mm and 1 mm.

14. An implantable intracardiac device (1) with a cylindrical housing (35) and a header assembly (3) according to any of the previous claims, wherein the feedthrough arrangement (5) is arranged at a distal end of the housing (35), wherein the feedthrough arrangement (5) is integrally formed with the housing (35) or is formed by a separate element which is fixed and hermetically sealed at a distal end face (37) of the housing