WO2025201714A1 - Header assembly for an implantable intracardiac device and respective intracardiac device - Google Patents

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 an envelope 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 envelope arrangement at least partially encloses the base ring and is in direct adherent contact to at least partial surfaces of the base ring. The envelope arrangement is configured such that at least parts of the envelope arrangement form an intermediate layer which is interposed between the base ring and the outer surface of the distal cap. The envelope arrangement is made with a first material and at least one of the proximal cap 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 relates to an implantable intracardiac device, such as an implantable intracardiac pacemaker, and a header assembly for such device.

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 slowly 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 visualized 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 an envelope arrangement. The feedthrough 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 envelope arrangement at least partially encloses the base ring and is in direct adherent contact to at least partial surfaces of the base ring. Furthermore, the envelope arrangement is configured such that at least parts of the envelope arrangement form an intermediate layer which is interposed between the base ring and the outer surface of the distal cap. The envelope arrangement is made with a first material and at least one of the proximal cap and the distal cap is made with a second material, wherein the first material is 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 summarizing 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 feedthrough 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. Furthermore, at least parts of the base ring are enclosed in soft material forming an envelope arrangement which adherently contacts at least partial surfaces of the base ring. As the distal cap is fixed via the feedthrough arrangement to the housing of the ID, the base ring is therefore rotatable with respect to the housing while at the same time being flexibly interposed or clamped between the distal cap and the proximal cap. Accordingly, due to, inter alia, the presence and characteristics of the envelope arrangement at the base ring, intentionally rotating the base ring e.g. due to major rotation forces may be enabled while unintentional rotation of the base ring e.g. due to minor rotation forces may be prevented, thereby reducing a risk of unintended dislocation or reorientation of the ID during actual service. Additionally, excessive forces acting onto the base ring may be prevented due to the presence and characteristics of the envelope arrangement, thereby possibly minimizing wear and extending the service life time of the implanted ID.

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

Briefly summarized, the implantable intracardiac device may be adapted for stimulating and/or monitoring cardiac activity. For example, the ID may be a pacemaker (particularly an implantable leadless pacemaker), a cardioverter, a defibrillator, a cardiac monitor or any other heart-related device. The header assembly proposed herein is configured for anchoring the ID at or within a patient’s tissue, particularly at cardiac tissue. Therein, the header assembly is fixed to a housing of the ID and comprises a base ring assembly including a base ring with flexible tines extending in a direction away from the housing such as to penetrate into the adjacent tissue. The base ring is held at the header assembly by clamping it between the ring-shaped proximal cap and the ring-shaped distal cap, the latter one being fixed to the cylindrical feedthrough arrangement by a formation of a locking connection.

Details, functionalities and characteristics of the components the header assembly including the feedthrough arrangement, the proximal cap, the distal cap and the base ring with its tines are described in the applicant’s prior patent applications PCT/EP2023/075727which are included herein in their entirety by reference.

Specifically, the header assembly presented herein shall comprise an envelope arrangement.

Such envelope arrangement shall be configured such that it encloses at least part of the base ring. Furthermore, the envelope arrangement shall be in direct adherent contact to at least partial surfaces of the base ring, i.e. in a gap-less mechanical contact to surfaces of the base ring such as to adhere to such partial surfaces. In other words, the base ring or at least parts thereof may be embedded within adherent material forming the envelope arrangement. The adherent contact may be established for example by producing the envelope arrangement with a material which may be processed in a liquid state such as to cover the respective surfaces of the base ring and which may then solidify. For example, as described below in further detail, such envelope arrangement may be formed using processes such as injection molding or dipping (e.g. dip coating), wherein such processes may easily and/or reliably be implemented on an industrial scale.

The first material of which the envelope arrangement consists or with which the envelope arrangement is made may be electrically isolating. Preferably, it may be a polymer material. For example, it may be an elastomer. Furthermore, such first material may be provided such as to be initially in a liquid state in which it may easily be processed and such that it may then be solidified for example in a curing procedure.

Furthermore, the envelope arrangement is configured such that at least a part of it is interposed between the base ring and the distal cap, such part being referred to herein as intermediate layer. Due to such intermediate layer, the outer surface of the distal cap is not in direct mechanical contact with an opposing surface of the base ring. Instead, the intermediate layer formed by the envelope arrangement is interposed between both components and may therefore serve as a flexible and preferably elastic buffer structure. Accordingly, forces, torques or moments acting onto at least one of the proximal cap and the feedthrough arrangement and the housing of the ID attached thereto are not directly transmitted to the base ring with its tines being anchored into adjacent tissue. Instead, such forces, torques or moments are transmitted via the intermediate layer formed by the envelope arrangement and are therefore damped and/or distributed. Accordingly, excessive wear or even damages at the base ring and its tines may be prevented even though the ID with its header assembly being anchored in cardiac tissue is repeatedly displaced in conjunction with continuous cardiac motions. Accordingly, mechanical stress and resulting wear at the base ring and the tines may be reduced and the service life of the header and the entire ID may be extended. In order to enable efficient damping and/or spreading of forces, torques or moments, the envelope arrangement is made with a first material being softer than a second material with which the proximal cap and/or the distal cap are made.

Particularly, according to an embodiment, the first material may have a Shore A hardness of between 10 and 100, preferably between 20 and 70 or between 30 and 50.

In other words, the envelope arrangement may be made with a soft first material in a durometer range of Shore A between 10 and 100, most likely between Shore A 30 and 50. In comparison hereto, the second material may have a Shore A hardness which is e.g. at least 10%, preferably at least 30%, 50% or even 100% higher or which has a significantly higher hardness to be measured in other scales such as a Shore D scale.

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.

Liquid Silicone Rubber (LSR) is a silicone-type material. It may be processed in an initially liquid state using a LSR process. Such LSR process is a method for manufacturing molded parts from silicone rubber by injection molding 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 envelope arrangement 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, an electrical isolation as well as sufficient chemical resistance against a harsh chemical environment in cardiac applications.

Alternatively, the first material is polyurethane (e.g. TPU, TPE..) which may be made having the durometer/hardness as mentioned above. The envelope arrangement may be made by covering the at least partial surfaces of the base ring with the first material in injection molding process or dip coating process.

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

In other words, the distal cap and/or the proximal 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.

According to an embodiment, the envelope arrangement completely encloses the base ring

Expressed differently, the entire base ring may be embedded within the material forming the envelope arrangement. In such completely enclosed configuration, the soft first material covers, inter-alia, the entire surface of the base ring directed to the outer surface of the distal cap. Thereby, the intermediate layer formed by such material may efficiently and and/or distribute forces which are to be transmitted between the distal cap and the base ring. Particularly, the intermediate layer may be continuous and free from any gaps. Producing the envelope arrangement such as to completely enclose the base ring may be easily and reliably established on an industrial scale. For example, the base ring may be submitted to or dipped into liquid first material such that the material flows along and around the entire structure of the base ring.

As an alternative hereto, the envelope arrangement might enclose only parts of the base ring. For example, the soft first material may be interposed only between partial surfaces of the base ring and parts of the outer surface of the distal cap. Accordingly, the intermediate layer may be non-continuous and there may be gaps between neighboring portions of the intermediate layer. Thereby, inter alia, an amount of required first material may be reduced.

According to an embodiment, the envelope arrangement is made by covering the at least partial surfaces of the base ring with the first material in a liquid silicone rubber injection molding process.

LSR injection molding is a process which may be implemented on an industrial scale in a reliable and cost-efficient manner. Therein, an LSR component is produced from a 2- component LSR material. Such material is generally composed of two base materials comprising thermosetting elastomers. The base materials as well as the composition of both is initially in a liquid state in which it may be injected into a mold. Upon mixing the base materials, the composition of both materials subsequently solidifies. Such solidification procedure may be accelerated at elevated temperatures. Accordingly, the mold is typically heated to temperatures above 100°C or even above 150°C. The solidification process may also be referred to as vulcanization.

LSR injection molding may be particularly beneficial for preparing the envelope arrangement for the header assembly proposed herein as it may be implemented such as to overmold the base ring or at least parts thereof in a highly precise manner. Therein, the base ring together with its tines may be held within the mold in a predefined configuration and location upon liquid LSR material being injected into the mold. After subsequent solidification of the LSR material, it may form an overmolded layer into which the base ring is partially or completely embedded. Furthermore, LSR injection molding allows for generating smooth surfaces thereby enabling preparing the envelope arrangement with a smooth surface at the interface to the adjacent distal cap. Thereby, a defined friction may be established between the base ring enclosed by the envelope arrangement, on the one hand, and the distal cap fixed to the housing of the intracardiac device, on the other hand.

According to an alternative embodiment, the envelope arrangement is made by dipping the at least partial surfaces of the base ring into the first material being in a liquid form and subsequently solidifying the first material.

In other words, the envelope arrangement may be produced by dipping the base ring or at least portions thereof into the liquid first material, i.e. for example by dipping into liquid LSR material. As a result of such dipping process, a thin layer of first material adheres to the dipped surfaces. Subsequently, such thin layer may be solidified by for example applying energy such as by heating the first material to an elevated temperature of for example more than 100°C more than 150°C. Optionally, the dipping and/or solidification process may be repeated several times.

Such dipping processing may be particularly beneficial for preparing the envelope arrangement for the header assembly proposed herein as it may be implemented in a very simple manner and/or on an industrial scale.

The specific manner with which the envelope arrangement is produced using LSR injection molding or dipping, as described before, generally results in process-specific intrinsic characteristics of the product resulting from such processing, i.e. of the produced envelope arrangement. For example, the envelope arrangement may have some microscopic characteristics such as solidified polymer structures and/or some macroscopic characteristics such as edges or flow structures typically resulting from such processing.

According to an embodiment, the envelope arrangement covers at least partial surfaces at both of opposing surfaces of the base ring. In other words, the first material is embedding the base ring in a manner such that both opposing surfaces of the base ring are covered with first material. For such purpose, the base ring may for example be arranged in a mold of an LSR injection molding device in such a manner that it is spaced from inner surfaces of the mold such that liquid LSR material may reach both opposing surfaces of the base ring. Alternatively, the base ring may be dipped into liquid first material such that the first material may flow to each of the opposing surfaces of the base ring. Accordingly, the base ring together with its tines and the envelope arrangement may form a unit which may be produced and/or handled separately from the proximal cap and the distal cap.

According to an additional or alternative embodiment, the envelope arrangement encloses the base ring together with the proximal cap.

In such implementation, the envelope arrangement does not only embed the base ring but additionally embeds also the proximal cap. For such purpose, both, the base ring and the proximal cap may be arranged e.g. in a mold of an injection molding device such that injected liquid and curable first material may cover both components. Alternatively, both components may be dipped into such first material together. As a result, upon solidifying the first material, the generated envelope arrangement encloses both the base ring and the proximal cap, thereby forming a unitary component which may for example be easily handled.

According to an embodiment, the intermediate layer formed by the envelope arrangement has a thickness of between 0.05 mm and 1 mm, preferably between 0.1 and 0.3 mm.

In other words, a dimension of the intermediate layer 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 0.05 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. 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.

Embodiments of 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 a base ring assembly for the inventive header assembly of Fig. 1 in a perspective view,

Fig. 3 shows the header assembly of Fig. 1 in an assembled cross-sectional side view,

Fig. 4 shows the header assembly of Fig. 1 in an assembled perspective view,

Fig. 5 shows an alternative embodiment of an inventive implantable ID with an inventive header assembly in a longitudinal-sectional, exploded and perspective view,

Fig. 6 shows a base ring assembly for the inventive header assembly of Fig. 5 in a perspective view,

Fig. 7 shows the header assembly of Fig. 5 in an assembled cross-sectional side view, Fig. 8 shows a comparative example of an implantable ID with a header assembly in a longitudinal-sectional, exploded and perspective view,

Fig. 9 shows a distal cap of the comparative example of Fig. 8.

Fig. 10 shows the header assembly of Fig. 8 in an assembled cross-sectional side view,

Fig. 11 shows a cross-sectional side view of a distal cap of another comparative example of a header assembly for an implantable ID.

Fig. 12 shows a perspective view of the distal cap of Fig. 11.

Fig. 13 shows a header assembly with the distal cap of Fig. 11 in an assembled cross- sectional side 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 assemblyl2 comprising a base ring 11 and four tines 13 radially and axially extending from the base ring 11, a washer-like steroid depot 39, a ring-shaped proximal cap 7, an envelope arrangement 15 enclosing the base ring 11 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 the outer diameter at its proximal end.

Each of the distal cap 9, the base ring 11, the steroid depot 39 and the proximal cap 7 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 center 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 envelope 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 consists of Nitinol, for example.

Specifically, the header assembly 3 comprises the envelope arrangement 15. The envelope arrangement 15 encloses the base ring 11. Particularly, material forming the envelope arrangement covers and adheres to at least partial outer surfaces of the base ring. An intermediate layer 31 formed by the envelope arrangement 15 is interposed between the outer surface 21 of the distal cap 9 and the base ring 11 of the base ring assembly 12. The envelope arrangement 15 is made with a soft first material which is softer than a second material of the distal cap 9 and/or a second material of the proximal cap 7. Accordingly, the envelope arrangement 15 has a higher deformability in and against a radial direction 29 perpendicular to the axial direction 27 than e.g. the fixing portion 23 of the distal cap 9. Having such specific configuration, the envelope arrangement 15 is configured to exert an elastic force in a radial direction 29, i.e. orthogonal to the axial center 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 envelope 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 envelope 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 envelope arrangement 15 consists of electrically isolating and elastic material being softer than the material of the distal cap 9. For example, it may consist of liquid silicone rubber. Due to its soft and deformable material, the envelope arrangement 15 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 harming or even damaging 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 - 4 visualize various characteristics that the header assembly of Fig. 1 in different views.

The envelope arrangement 15 embeds the base ring 11 of the base ring assembly 12 such as to cover both opposing main surfaces of such base ring 11. Accordingly, the base ring assembly 12 forms a unitary component together with the envelope arrangement 15. In the fully assembled state, the envelope arrangement 15 forms an intermediate layer 31 which is interposed between the base ring 11 and the opposing outer surface 21 of the distal cap 9. Such intermediate layer 31 may have a thickness of for example 0.1 mm. Such thickness corresponds approximately to the thickness of the base ring 11.

Due to its thickness and the soft and elastic properties of the first material forming the envelope arrangement 15, the intermediate layer 31 formed by the envelope arrangement 15 may absorb, damp and/or distribute excessive forces occurring between the distal cap 9 and/or the proximal cap 7, on the one side, and the base ring assembly 12, on the other side. Additionally, the envelope arrangement 15 may provide for a specific friction between the base ring assembly 12 embedded therein, on the one side, and the distal cap 7 and/or the proximal cap 7, on the other side, such that the base ring assembly 12 may be rotated relative to the caps 9, 7 and the housing 35 coupled thereto.

Figs. 5 - 7 visualize an alternative embodiment of a header assembly 3 and, particularly, of the envelope arrangement 15 comprised therein. While many other characteristics and functionalities of such embodiment are identical or similar those in the embodiment of Figs. 1 - 4, the envelope arrangement 15 in the alternative embodiment encloses not only the base ring 11 of the base ring assembly 12 but also encloses the proximal cap 7. Accordingly, the proximal cap 7 and the base ring assembly 12 form a unitary component in which the base ring 11 together with the proximal cap 7 are completely or at least partially embedded within the soft first material of the envelope arrangement 15.

Similar to the embodiment of Figs. 1 - 4 described above, the envelope arrangement 15 forms an intermediate layer 31 interposed between the base ring 11 and the distal cap 9 in order to serve as a kind of buffer for absorbing excessive forces as well as for providing sufficient friction between the mentioned unitary component on the one side, and the distal cap 9, on the other side.

Figs. 8 - 10 visualize a comparative example of a header assembly 3 and of its components. While the general structure of such comparative example is similar to the header assembly 3 as described above, it does not comprise an envelope arrangement 15 enclosing the base ring 11. Instead, a pressing arrangement 16 is provided at the distal cap 9. Particularly, such pressing arrangement 16 is provided at an outer surface 21 of the distal cap 9. Accordingly, in an assembled state of the header assembly 3, such pressing arrangement 16 is interposed between the outer surface 21 of the distal cap 9, on the one side, and the opposing surface of the base ring 11, on the other side. Such pressing arrangement 16 may be made of a similar material as the soft first material used for the envelope arrangement 15 discussed above. Accordingly, the pressing arrangement 16 may provide for some force absorbing characteristics as well as fiction generating characteristics. The pressing arrangement 16 may be molded onto an outer circumference of the distal cap 9. Therein, a radial protrusion 61 provided at the distal cap 9 may serve for stabilising the pressing arrangement 16.

Figs. 11 -13 visualize another comparative example of a header assembly 3 and of its components. Therein, the pressing arrangement 16 is again provided at an outer circumference of the distal cap 9 at the outer surface 21. However, a positioning of such pressing arrangement 16 differs as compared to the embodiment shown in Figs. 8 - 10. Specifically, the pressing arrangement 16 is attached to the distal cap 9 along the outer surface 21 of distal cap 9 at a position underneath a radially extending rim 63 radially protruding at a top end of the distal cap 9.

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.

Finally, possible characteristics and advantages of embodiments of the header assembly and the intracardiac device proposed herein are described with slightly different wording:

Briefly summarized, this disclosure comprises a header design and a method for connecting a header with an implantable device. A uniaxial assembly is preferred for easy automation.

A design described in this disclosure reduces component complexity for a cost effective and safe product. Due to a soft embedding of tines inside the device header this disclosure enables a maximum degree of compliance of the connected tines preventing tine breakages without impacting long-time fixation of the tines to the implant.

Embodiments of the invention may facilitate a size and component reduced header assembly to connect tines to an implant in the heart. No gluing processes are needed. No rotational fixation methods are needed. Just uniaxial assembly ready for automation even for miniature components is enabled.

The invention ensures a long-term stable connection, in one embodiment ensuring a nearly free captured tine-array for maximum compliance and lowest restrictions to minimize high strain in the tine material and thus provide a maximum safety margin.

Known solutions need sophisticated alignment methods to fixate 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 filigree bayonet features is needed to combine a header with a housing. Furthermore, for the fixation of the tines complicated injection molded parts with notches are needed to receive the tines. All solutions in common are hard to automate. Because of a use of silicone adhesive, manual cleaning procedures are generally needed after assembly.

Known solutions may have, inter alia, the following drawbacks:

- Known solutions are not or hard to automate since they require multiaxial alignment methods or count on adhesive application.

- Complex isolating parts with notches are needed

- Height of the header is relatively big

- A tine array that is fixedly attached inside the implant’s header is quite stiff at its base and cannot comply with all the heart muscle movements in axial, radial and lateral directions that deflect the tines in the same directions. Especially when situated in notches inside the header, the tine arms cannot comply very good with lateral tine tip movements that lead to high strain in the tine material at its base where the tine arms exit the header. Such a stiff coupling of the tines could lead to tine breakages over the implant’s life-time There may therefore exist the following tasks:

- The task is to realize a cap for uniaxial assembly of a header

- The header assembly has the following functions:

Permanent connection of a tine array at an implant

Electrical isolation the tines from the implant housing

Permanent fixation of a steroid depot at an implant

Enable uniaxial assembly

Enable a non-reversible, permanent header fixation

Enable a maximum degree of compliance of the connected tines without impacting longtime fixation of the tines to the implant

Create friction to the tine ring to minimize tine rotation but at the same time work as a safety clutch if high external forces are applied to one or more tine arms.

The solution proposed herein may, inter alia, comprise:

- a uniaxial stackable assembly configuration is used.

- The fixation of all the header components is done by a method not using adhesive bonding forces or sophisticated connection methods (threaded, bayonet) but use the elastic and plastic material properties of the thermoplastic polymer upper cap itself to achieve a reliable longterm stable connection to the implant housing.

- During assembly the diameter of the upper header cap will be stretched to a certain degree (such that the header cap does not break). Pushing the cap further, the header cap snaps over a retention feature of the feedthrough flange/implant housing. The combination with retention features of the feedthrough flange or housing proves this snap-fit connection as a permanent fixation.

- The upper header cap is designed as a two part component consisting of at least two polymers, one with a high elastic modulus and another one with a low elastic modulus (e.g. Shore 30 or shore 50).

- The combination of the lower header cap and the upper header cap will create a circumferential cavity that provides space for the ring portion of the tine array and the tines itself. Because the upper header cap has a second soft component in the neighborhood of the tine, the tine array ring can comply against the soft embedding to external forces applied to the tine arms. This soft embedding allows that the deflection applied to the tines by the heart tissue movement to be distributed more evenly in the tine material, thus mitigating strain hot spots in the tine material that could lead to tine breakages.

- In the same moment the tine array is kept attached to the device by the upper cap, such that the tine ring cannot escape the header

In an implementation forming a comparative example as represented in Figs. 8 - 13, the following features may be realized:

•A two-part header (e.g. lower or intermediate part and upper part) will be manufactured from insulating materials. PEEK is ideal because of its mechanical strength, Silicone is ideal because of its softness. Both materials are biocompatibile and provide excellent insulation characteristics.

•The upper Header cap will be made out of a thermoplastic inner part with a high material strength (e.g. PEEK) to ensure a long term stable fixation to the device.

•The outer portion of the header cap will be made out of a material with a soft elastic modulus (e.g. silicone, PU, TPU, TPE) to softly embed the tines.

•The lower cap is used to ensure electrical isolation of the tine array to the housing and to accommodate the tine array.

• The lower cap features a conus shape surface to receive the tine array

•The ring of the tine array has also a conical shape that fits into the conical shape of the lower cap

•The tine ring is situated in the cavity in between the two caps and is retained by the upper cap.

•The tine ring itself is not fixedly attached, thus it can comply and can help to distribute the strain originating from the tine deflection. This degree of freedom can help to increase the long time fatigue of the tine array, being exposed to approx. 400 Mio. heart beat cycles in a ten year’s implant life time.

•The tine array cannot be removed out of the cavity formed by the two caps and and is permanently locked to the implant

•Furthermore, the upper cap may feature a rim on the upper section to fixate a steroid depot to the implant as well. •The elastic component of the upper header cap ensures the permanent force on the tine ring, which ensures a friction-controlled torque. This mentioned elastic feature can be made of e.g. a silicone or polyurethane (e.g. TPU, TPE..). This feature will act as a safety-clutch mechanism: Excessive force applied to the tines (e.g. by human misuse during implantation) will lead to a rotational movement of the tines around the device axis yielding the excessive force and preventing further damage to the tines.

•At the same time, a defined brake-loose torque will ensure a static rotational position of the implant once implanted in the heart tissue. This circumstance ensures reliable follow up procedures in cases the communication capability of the implant has a preferred communication orientation by using coil induced electrical field communication.

•Feature of component can be a proud or recessed circumferential or partial circumferential feature to enhance silicone to PEEK adhesion around the feature due to surface area increasement or undercut features. One or more features are possible.

• In an alternative embodiment of the component, the elastic sub-component may be positioned below the protruded sub-feature of the inner Header cap.

There is a variant embodiment as represented in Figs. 1 - 4 with tine overmold or tine dip characteristics as follows:

•The tine-array will be over molded or dipped into silicone, PU, TPE, TPU such that the soft embedding and the tine become one part.

•The Overmold can be realized by e.g. a silicone dipping process (one or several dipping repetitions to achieve proper silicone thickness)

•The coating can extend to the tine-arms much higher, such that the coating acts as a strain relief component for the tine material itself. In-vivo strains applied to the tines by the heart tissue can be reduced by that cover.

•The overmolded tine-array will be positioned (and maybe slightly compressed) in between the conical surfaces of the upper header cap and the conical sur-face of the lower header cap •The overmold could be partial in sections distributed around the circumference, too. Not necessarily a complete overmold is necessary.

Furthermore, there is a variant embodiment as represented in Figs. 5 - 7 with tine overmold with lower header cap geometry out of silicone, PU, TPU, TPE etc. •Component of the lower header cap (previous variants) will be substituted completely and will be integrated in component

•The Tine- Array will be overmolded with an elastic material such as silicone, PU, TPE, TPU so that the soft embedding and the tine-array become one part.

•The overmold) can be realized by e.g. a silicone dipping process (one or several dipping repetitions to achieve proper silicone thickness)

•The coating can extend to the tine-arms much higher than illustrated, such that the coating itself can act as a strain relief feature for the tine material itself. In-vivo strains applied to the tines by the heart tissue can be reduced by that coating taking over some percentage of that strain.

•The overmold tine-array will be positioned (and maybe slightly compressed) in between the conical surfaces of the upper header cap and the conical surface of the lower overmolded tine array.

•The overmold could be partial in sections distributed around the circumference, too. Not necessarily a complete overmold is necessary.

Possible advantages of embodiments of the invention are, inter alia:

•No gluing necessary because of a snap-fit permanent connection (e.g. rotation of the cap without gluing would release cap of an bayonet joint like on Mi era MDT) •Automated assembly friendly (uniaxial assembly)

•Reduction in header height

•Because of a not fixedly attached but a soft embedded tine array inside the implants header, strain hot spots are mitigated in the tine material that could lead to tine break-ages.

•Tine rotation is prevented by friction, in the same instance having a safety clutch mechanism when excessive strain should be applied to the tines. 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 envelope arrangement

16 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

31 intermediate layer

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 61 radial protrusion at distal cap

63 radially extending rim at distal cap

Claims

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 an envelope 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 envelope arrangement (15) at least partially encloses the base ring (11) and is in direct adherent contact to at least partial surfaces of the base ring (11) and wherein the envelope arrangement (15) is configured such that at least parts of the envelope arrangement (15) form an intermediate layer (31) which is interposed between the base ring (11) and the outer surface (21) of the distal cap (9), wherein the envelope arrangement (15) is made with a first material and wherein at least one of the proximal cap (7) 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 one of the preceding claims, wherein the first material is liquid silicone rubber.

4. The header assembly according to one of the preceding claims, wherein the second material is polyetheretherketone.

5. The header assembly according to one of the preceding claims, wherein the envelope arrangement completely encloses the base ring.

6. The header assembly according one of the preceding claims, wherein the envelope arrangement (15) is made by covering the at least partial surfaces of the base ring (11) with the first material in a liquid silicone rubber injection molding process.

7. The header assembly according to one of claims 1 to 5, wherein the envelope arrangement (15) is made by dipping the at least partial surfaces of the base ring (11) into the first material being in a liquid form and subsequently solidifying the first material.

8. The header assembly according to one of the preceding claims, wherein the envelope arrangement (15) covers at least partial surfaces at both of opposing surfaces of the base ring (11).

9. The header assembly according to one of the preceding claims, wherein the envelope arrangement (15) encloses the base ring (11) together with the proximal cap (7).

10. The header assembly according to one of the preceding claims, wherein the intermediate layer (31) formed by the envelope arrangement (15) has a thickness (Tl) of between 0.05 mm and 1 mm.

11. 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