Implantable intracardiac device with optimized header assembly and TINE arrangement for reduced component fatigue

Abstract

An implantable intracardiac device (1) comprising a housing (3) and a header assembly (5) attached to an end face of the housing is described. The header assembly comprises a ring- shaped proximal header base (7), a ring-shaped distal header cap (9) and tine arrangement (11) being at least partially interposed between the header base and the header cap. The tine arrangement comprises a base ring (23) and at least two elongated tines (25) protruding distally from the base ring. The tine arrangement further comprises, at each associated one of the tines, two notches (39) extending into the base ring at opposing sides of the associated tine, each of the notches being positioned at a transition location (27) between the base ring and the associated tine. Alternatively or additionally, the tine arrangement is sandwiched between an outer ring-shaped surface (33) of the header base and an inner ring-shaped surface (35) of the header cap, wherein the header base (7) at its outer ring-shaped surface (33) and the header cap (9) at its inner ring-shaped surface (35) are each rounded and convex such that a distance (D) between the outer ring-shaped surface of the header base and the tine as well as a distance between the inner ring-shaped surface of the header cap and the tine continually increases along a protrusion direction (PD) of the tine.

Description

[0001] Applicant: BIOTRONIK SE & Co. KG

[0002] Date: 11.12.2025

[0003] Our Reference: 23.148P-WO

[0004] IMPLANTABLE INTRACARDIAC DEVICE WITH OPTIMIZED HEADER ASSEMBLY AND TINE ARRANGEMENT FOR REDUCED COMPONENT FATIGUE

[0005] The present invention relates to an implantable cardiac device such as a leadless pacemaker.

[0006] Implantable cardiac devices may be implanted in a body of a patient e.g. for supporting and / or monitoring physiological functions in a patient’s heart. For example, a pacemaker may be implanted for stimulating cardiac activity of the patient. Particularly, miniaturized implantable leadless pacemakers (iLP) have been developed which may be implanted directly into a cardiac chamber of a patient’s heart such that an electrode contacts cardiac tissue. Accordingly, cardiac activity may be stimulated by applying electric pulses via the electrode.

[0007] Generally, the implantable cardiac device is to be arranged and fixed reliably within the body at a predetermined location to enable fulfilling its intended function. For example, the iLP is to be arranged and fixed within the cardiac chamber such that electrical pacing pulses may reliably and effectively be transmitted to cardiac tissue such as to thereby stimulate motions of the heart.

[0008] For such purpose, implantable cardiac devices typically comprise a housing, a fixation mechanism and an electrode structure. The housing typically accommodates various components such as a controller and an energy source. The fixation mechanism is configured for correctly and reliably fixing the housing in relation to the patient’s body. The electrode structure serves for establishing an electric contact between the device and tissue of the patient’s body to thereby allow transmitting electric pulses to the tissue and / or to measure electric characteristics at the tissue. Approaches have been developed in which the fixation mechanism of the implantable cardiac device comprises a header assembly which is fixed to the housing of the device and which itself comprises multiple tines. These tines are typically elongate structures made of a biocompatible material such as Nitinol which may be introduced into the patient’s tissue to form tine-based anchors. Accordingly, using the header assembly and its tine arrangement, the implantable cardiac device may be anchored reliably at an intended implantation site.

[0009] For example, WO 2022 / 214247 Al discloses an implantable intracardiac device and a header assembly for such device as well as a method for manufacturing the same. Furthermore, WO 2024 / 074299 discloses a header assembly for an implantable intracardiac device and a respective intracardiac device. At least some of the features described in the cited documents may be applied in a same or similar manner to the implantable intracardiac device described herein. The content of the cited documents shall be incorporated herein in its entirety by reference.

[0010] There may be a need for an improved implantable intracardiac device. Particularly, there may be a need for an implantable intracardiac device which is specifically configured for being fixed at a patient’s tissue with superior long-term reliability.

[0011] Such needs may be met with the subject matter of the independent claims. Advantageous embodiments are defined in the dependent claims as well as the corresponding specification and figures.

[0012] According to a first aspect, an implantable intracardiac device comprising a housing and a header assembly attached to an end face of the housing is described. The header assembly comprises a ring-shaped proximal header base, a ring-shaped distal header cap and tine arrangement being at least partially interposed between the header base and the header cap. The tine arrangement comprises a base ring and at least two elongated tines protruding distally from the base ring. The tine arrangement further comprises, at each associated one of the tines, two notches extending into the base ring at opposing sides of the associated tine,

[0013] 23.148P-WO / 11.12.2025 each of the notches being positioned at a transition location between the base ring and the associated tine.

[0014] According to a second aspect, an implantable intracardiac device comprising a housing and a header assembly attached to an end face of the housing is described. The header assembly comprises a ring-shaped proximal header base, a ring-shaped distal header cap and tine arrangement being at least partially interposed between the header base and the header cap. The tine arrangement comprises a base ring and at least two elongated tines protruding distally from the base ring. The tine arrangement is sandwiched between an outer ringshaped surface of the header base and an inner ring-shaped surface of the header cap. The header base at its outer ring-shaped surface and the header cap at its inner ring-shaped surface are each rounded and convex such that a distance between the outer ring-shaped surface of the header base and the tine as well as a distance between the inner ring-shaped surface of the header cap and the tine continually increases along a protrusion direction of the tine.

[0015] Briefly summarised and without limiting the scope of the invention, basic ideas underlying embodiments of the invention and associated possible advantages will be roughly described as follows:

[0016] Embodiments of the invention described herein may be interpreted as being based, inter alia, on findings indicating that a long-term reliability and fixation of an implantable intracardiac device are generally influenced significantly by characteristics of its header assembly and its tine arrangement comprised therein.

[0017] Particularly, it has been observed that elongated tines of a tine arrangement may suffer from deformations and / or fatigue upon being initially significantly deflected during an implantation procedure for fixing the intracardiac device at an implantation site and / or during repeated deflections during the device’s operation as a result of continuous heart motions.

[0018] 23.148P-WO / 11.12.2025 To avoid malfunctions of the intracardiac device resulting, for example, from defects at its header assembly, it is suggested herein to include notches at specific locations of the tine arrangement directly at transition locations between the base ring and each one of the tines. Such notches may help to prevent local excessive mechanical stresses and may therefore serve as stress relief notches. Due to such stress relief notches, mechanical stress occurring upon bending the tines may be distributed more evenly throughout the tine arrangement, thereby preventing excessive material fatigue or even breakages within the tine arrangement.

[0019] Furthermore, it has been observed that characteristics of the proximal header base and the distal header cap may influence how the tine arrangement is interposed between these components in a sandwiched fashion as well as how the elongated tines may be bent upon being deflected. Particularly, it has been found that the outer ring-shaped surface of the header base as well as the inner ring-shaped surface of the header cap should be contoured such that any point-like fulcrum may be avoided and the tines may flex smoothly upon being deflected. For such purpose, it is suggested that the outer surface of the header base and the inner surface of the header cap are each rounded smoothly in a convex shape such that a lateral distance between these surfaces, on the one side, and the tine emerging from between these surfaces upon the tine arrangement being sandwiched in the space between, on the other side, continuously increases along a direction in which the tine protrudes distally from the header assembly.

[0020] In the following, possible features of embodiments of the invention and associated possible advantages will be described in more detail.

[0021] The implantable intracardiac device may be a miniaturized device which may be implanted into a chamber of a patient’s heart. For example, such device may be provided as an implantable leadless pacemaker (iLP). Such iLP may be introduced into a ventricle or an atrium of the heart using a catheter arrangement and may then be fixed at cardiac tissue such that an electrode of the iLP electrically contacts such tissue, thereby enabling transmitting electric pulses from the iLP for stimulating cardiac activity.

[0022] 23.148P-WO / 11.12.2025 The intracardiac device comprises a housing. Such housing generally accommodates components of the intracardiac device such as a controller for controlling functions of the device, an energy source such as a battery for supplying power to the controller and / or other components. The housing generally has small dimensions such as to enable introducing the housing into a cardiac chamber. For example, the housing may have a length of between 1 cm and 6 cm, preferably between 2 cm and 4 cm. Furthermore, the housing may be cylindrical and may have a diameter of typically between 1 mm to 10 mm, in particular between 2 mm and 5 mm. The housing may be made with, covered with or consist of biocompatible material.

[0023] Furthermore, the intracardiac device comprises a header assembly. Such header assembly is attached to the housing at an end face thereof. The header assembly serves as a fixation mechanism for fixing the intracardiac device at cardiac tissue. For such purpose, the header assembly includes a tine arrangement. Such tine arrangement comprises a base ring and at least two elongated tines distally protruding from such base ring. Generally, the base ring may be circular. Two, three, four or even more tines may emerge and protrude from such base ring in a direction transverse to, preferably perpendicularly to, the base ring. The tines may be distributed evenly and / or symmetrically along a circumference of the base ring. For example, each of the tines may be curved into a baseline curvature having e.g. a hook-like shape. For example, the tines may have a bent extension, particularly a semi-circular extension. Therein, at least portions of the tines may extend in a distal direction, i.e. a direction away from the header and away from the housing, and / or at least portions of the tines may extend in a radially outward direction.

[0024] The base ring and the tines may form an integral component. For example, according to an embodiment, the tine arrangement including the base ring and the tines may be cut from a tube stock made of biocompatible metal material such as Nitinol and subsequently shaped and heat set into a form where each individual tine has a baseline curvature. In other words, the tine arrangement may be made by, first, providing a tube stock including a thin-walled cylinder of e.g. Nitinol material, then cutting such tube stock such as to generate elongate structures forming tines emerging from a common Nitinol base ring and, finally, heating the

[0025] 23.148P-WO / 11.12.2025 entire component and simultaneously deforming its individual tines into an intended final shape with the tines having a baseline curvature.

[0026] In the header assembly, the tine arrangement is, at least partly, interposed between a ringshaped proximal header base and a ring-shaped distal header cap. Particularly, at least a portion of the base ring or the entire base ring of the tine arrangement and, optionally, additionally a portion of the tines directly adjacent to such base ring may be sandwiched between an outer ring-shaped surface of the header base and an opposing inner ring-shaped surface of the header cap such as to be stably clamped and held between the header base and the header cap.

[0027] In such header assembly, in accordance with embodiments of the first aspect of the invention, the tine arrangement, in particular the base ring, shall be specifically configured such as to comprise several notches serving as stress relief notches. For such purpose, each of the notches should be specifically arranged in a direct neighborhood to an associated one of the tines. Particularly, each of the tines comprises associated thereto two notches. These notches are arranged at opposing sides of the associated tine and extend into the base ring at a transition location between the base ring and the associated tine.

[0028] In other words, instead of providing the base ring of the tine arrangement with a constant width and letting the tines emerge from such base ring using for example a simple rounded fillet, it is suggested to include stress relief notches in the base ring such that the base ring has a locally decreased width and to arrange such stress relief notches at locations where the individual tines emerge from the base ring.

[0029] Again expressed differently, the notches may be arranged immediately adjacent to the associated tine with regards to a circumferential direction of the base ring. Therein, a distance between the notches and the associated tine in the circumferential direction of the tine may be zero or may be at least smaller than a distance to a neighboring one of the notches in the circumferential direction and / or may be at least smaller than 1 mm.

[0030] 23.148P-WO / 11.12.2025 Due to the provision of such stress relief notches, mechanical stress occurring between the tines and the base ring may be pushed away from the transition location where the tines emerge from the base ring and / or may be distributed further into a bulk of the base ring. Accordingly, tine fracture risks as a result of extensive tine deformation and / or repetitive tine deflection may be reduced.

[0031] According to an embodiment, the notches are configured as rounded divots carved into the base ring. In other words, the stress relief notches may have a rounded shape and are introduced as rounded cuts or grooves into the base ring. Therein, one boundary of the notch may smoothly transition into a boundary of the associated tine whereas an opposite boundary of the notch may transition into a boundary of the base ring. Such rounded divots may have a beneficial effect on a distribution of mechanical stress in a neighborhood of the transition location at which the associated tine emerges from the base ring.

[0032] Particularly, according to an embodiment, the rounded divots have a semi-circular contour. Expressed differently, each stress relief notch may have a semi-circular shape. Such semicircular shape may be specifically advantageous for distributing any mechanical stress at the transition between the associated tine and the base ring.

[0033] For example, according to an embodiment, a width of the divots ranges from 10% to 100%, in particular from 10% to 50%, of a width of the associated tine. In other words, each divot forming a stress relief notch may have a width being larger than 10%, preferably being larger than 15% or being larger than 20% in comparison to a width (not a thickness) of the tine emerging at the transition location. However, such width of the notch should be smaller than 50%, preferably smaller than 40%, of the width of the tine. Such dimensions of the divots have been found to be beneficial for effectively distributing any mechanical stresses away from the transition location upon bending the tine.

[0034] According to a further embodiment, the divots protrude into the base ring as a finger-like intrusion to a depth ranging from 5% to 50% of a width of the base ring. In other words, each of the divots may be shaped as an elongated, finger-like intrusion having a maximum depth of at least 5%, preferably at least 10% or at least 15%, and at most 50%, preferably at

[0035] 23.148P-WO / 11.12.2025 most 40%, of a width of the base ring. Accordingly, such divots have a significant depths, thereby providing for effective mechanical stress distribution while not extending excessively deep into the base ring and thereby preventing excessively weakening an integrity of the base ring.

[0036] In the header assembly, in accordance with embodiments of the second aspect of the invention, each of the outer ring-shaped surface at the header base and the inner ring-shaped surface at the header cap shall have a rounded and convex shape. This means, in a cross- sectional view, the outer ring-shaped surface at the header base as well as the opposing inner ring-shaped surface at the header cap are both curved with a convex curvature such that a lateral distance between both opposing surfaces increases in an over-proportional manner as a function of a distance from a region where both opposing surfaces have a minimum distance and clamp the tine arrangement by sandwiching it between both of opposing surfaces. In other words, at a most proximal portion of the header assembly, the tine arrangement and, particularly, its base ring is generally sandwiched and clamped between the outer ring-shaped surface of the header base and the inner ring-shaped surface of the header cap whereas, along a protrusion direction of the tines, the lateral distances between the tine and each of the opposing inner and outer surfaces of the header base and the header cap successively increases in a gradual and smooth manner. This means, the further distal and / or radially outwards one of the tines extends away from such sandwiched portion the larger is a lateral distance between the tine and the inner ring-shaped surface to the header cap, on the one side, as well as the larger is a lateral distance between the tine and the outer ring-shaped surface to the header base, on the other side.

[0037] Particularly, the lateral distance between the tine and each of the opposing inner and outer surfaces of the header base and the header cap, respectively gradually increases in an overproportional manner, i.e. not only linearly. This means that the further distal and / or radially outwards a portion of the tine is situated the further away and the more curved away the adjacent portion of the inner and outer surfaces of the header base and header cap, respectively, extends.

[0038] 23.148P-WO / 11.12.2025 Due to such specific shape of the inner and outer surfaces of the header base and the header cap, respectively, sandwiching and clamping the tine arrangement between both surfaces, it may be induced that, upon being deflected in a direction orthogonal to the tine protrusion direction, the tines may flex smoothly and point-like fulcrums forming targeted stress points may be avoided.

[0039] Accordingly, upon substantially deflecting the tines during a fixation procedure as well as during repeated deflection of the tines due to device motions in the beating heart, the tines may smoothly flex without inducing excessive local stresses at any fulcrums at which the tines abut at a non-curved or hardly curved portion of an adjacent surface of one of the header base or header cap.

[0040] Particularly, according to an embodiment, at least one of the outer ring-shaped surface of the header base and the inner ring-shaped surface of the header cap has a clamping topology being free of geometric discontinuities. In other words, at least one or more preferably both of the opposing inner and outer surfaces at the header base and header cap comprise a geometrically continuous shape having no sharp edges or changes in curvature. Due to such continuous geometry, the tines may smoothly abut or sit against a respective one of the surfaces upon being laterally deflected and any sharp and / or point-like fulcrums may be avoided.

[0041] According to a further embodiment, at least one of the outer ring-shaped surface of the header base and the inner ring-shaped surface of the header cap have a contour being represented by continuously differentiable functions. Expressed differently, a curvature of the outer and inner surfaces of the header assembly sandwiching the tine arrangement is set such as to be mathematically differentiable at all points along its surface profile, thereby avoiding any sharp edges or changes in curvature and, as a result, avoiding any sharp fulcrums.

[0042] It may be noted that characteristics described herein mainly with respect to embodiments of the first aspect of the invention and characteristics described herein mainly with respect to embodiments of the second aspect of the invention may be combined, thereby providing an

[0043] 23.148P-WO / 11.12.2025 implantable intracardiac device with even superior characteristics with regards to the header assembly and tine arrangement.

[0044] Furthermore, it shall be noted that possible features and advantages of embodiments of the invention are described herein partly with respect to various embodiments of an implantable intracardiac device. One skilled in the art will recognize that the features may be suitably transferred from one embodiment to another and features may be modified, adapted, combined and / or replaced, etc. in order to come to further embodiments of the invention.

[0045] In the following, advantageous embodiments of the invention will be described with reference to the enclosed drawings. However, neither the drawings nor the description shall be interpreted as limiting the invention.

[0046] Fig. 1 shows an exploded perspective cross-sectional view of an implantable intracardiac device according to an embodiment of the present invention.

[0047] Fig. 2 shows a cross-sectional view of the implantable intracardiac device of Fig.

[0048] 1.

[0049] Fig. 3 shows a tine arrangement for an implantable intracardiac device.

[0050] Fig. 4 shows an enlarged view of a portion of a tine arrangement for a conventional implantable intracardiac device.

[0051] Fig. 5 shows an enlarged view of a portion of a tine arrangement for an implantable intracardiac device according to an embodiment of the present invention.

[0052] Figs. 6(A)-(C) show cross-sectional views through various types of header assemblies of implantable intracardiac devices.

[0053] 23.148P-WO / 11.12.2025 Figs. 7(A)-(C) show sequences of deflecting tines at various types of header assemblies of implantable intracardiac devices.

[0054] Fig. 8 represents deflection characteristics of the tines indicated in Figs. 7(A)-

[0055] (C).

[0056] The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

[0057] Figs. 1 and 2 illustrate an exploded view and a cross-sectional view, respectively, of components of a first embodiment of an implantable intracardiac device 1, e.g. a leadless pacemaker, with a housing 3 and a header assembly 5.

[0058] The housing 3 has a cylindrical shape and accommodates for example a controller and a battery (not shown). At a distal end face 15, the housing 3 comprises a feedthrough 17 with a pin-shaped electrode 19 extending therefrom in a distal direction. The electrode 19 is isolated from the housing 3 by an interposed insulator 21.

[0059] The header assembly 5 comprises a ring-shaped proximal header base 7, a ring-shaped distal header cap 9 and a tine arrangement 11 with tines 25 extending from a common base ring 23. Furthermore, the header assembly 5 comprises a washer-like steroid depot 13. The distal header cap 9, the base ring 23, the steroid depot 13 and the proximal header cap 7 each comprise a central through-going opening for accommodation of the electrode 19. The components referred to in the previous sentence are axially symmetrical with regard to a longitudinal axial center axis 33 defining the axial direction.

[0060] The tine arrangement 11 comprises the common base ring 23 and several elongated tines 25 protruding distally and radially outwardly from the base ring 23. The base ring 23 may be preferentially conically formed in such way that a distal end of the base ring 23 has a greater inner and outer diameter compared with these diameters at its proximal end. The tines 25 emerge from the base ring 23 at transition locations 27. As described further below in more detail, notches 39 are provided at these transition locations 27. Each of the tines 25 has a

[0061] 23.148P-WO / 11.12.2025 curved shape with a baseline curvature starting from the common base ring 23 with a semicircular tine portion 29 and ending at a cantilever end with a straight tine portion 31. In other words, the tines 25 extend from the conical shaped base ring 23, wherein each tine 25 has an abutting section (flex zone) which transitions to the base ring 23, a curved middle section and a straight end section (furthest from the base ring 23). The tines 25 provide for a mechanical fixation of the intracardiac device 1 within the patient's heart after deployment and penetration of the heart's tissue such that the central electrode 19 is in mechanical and electrical contact with the inner tissue of the patient's heart within one ventricle or atrium. The proximal header cap 7 ensures electric isolation of the tines 25 from the housing 3. The tine arrangement 11 including the base ring 23 and the tines 25 are provided as an integral component and consist of biocompatible metal such as Nitinol, for example.

[0062] To fix the tine arrangement 11 relative to the housing 3, the header assembly 5 comprises an outer ring-shaped surface 33 at the proximal header base 7 as well as an inner ring-shaped surface 35 at the distal header cap 9. The base ring 23 of the tine arrangement 11 is then sandwiched and clamped between such outer ring-shaped surface 33 and inner ring-shaped surface 35. The distal header cap 9 and the proximal header base 7 each consist of electrically isolating and elastic material, for example PEEK.

[0063] Fig. 3 shows a perspective view of a tine arrangement 11. Fig. 4 and Fig. 5 each show an enlarged view of a portion “X” indicated in Fig. 3 at a transition location 27 where one of the tines 25 emerges from the base ring 23. Therein, Fig. 4 shows a conventional tine arrangement 11 according to the prior art at which the tine 25 projects from the base ring 23 with a simple rounded fillet 37.

[0064] In contrast hereto, Fig. 5 shows a tine arrangement 11 for an intracardiac device according to an embodiment of the present invention. Therein, two notches 39 are arranged at opposite sides of an associated tine 25. The notches 39 are positioned at the transition locations 27 immediately adjacent to the associated tine 25 and extend into the base ring 23. The notches 39 serve as stress relief notches and are configured as rounded divots 41 carved into the base ring 23. The rounded divots 41 have a semicircular contour. A width “wl” of the divots 41 ranges from 10% to 100%, in particular from 10% to 50%, of a width “w2” of the associated

[0065] 23.148P-WO / 11.12.2025 tine 25. Furthermore a depth “d” of the divots 41 ranges from 5% to 50% of a width “w3” of the base ring 23.

[0066] Figs. 6(A), (B), (C) show cross-sectional views through header assemblies 5 in different scenarios. Therein, the tine arrangement 11 is sandwiched between an outer ring-shaped surface 33 of the header base 7 and an inner ring-shaped surface 35 of the header cap 9.

[0067] In the “worst-case scenario” shown in Fig. 6(A), the tine 25 of the tine arrangement 11 “suddenly emerges” from between the header base 7 and header cap 9. In such scenario, stresses are concentrated at the sharp transition location 27 where the tines 25 emerge from the “sandwich”.

[0068] In the scenario shown in Fig. 6(B), which is preferably applied in intracardiac devices 1 according to the present invention, both the outer ring-shaped surface 33 at the header base 7 and the inner ring-shaped surface 35 at the header cap 9 are rounded and convex such that a distance “D” between the respective surfaces 33, 35, on the one hand, and the tine 25, on the other hand, continually increases gradually along a protrusion direction “PD” of the tine 25. Accordingly, the respective surfaces 33, 35 are continuously curved in an convex manner and are therefore free of any geometric discontinuities.

[0069] Fig. 6(C) shows an alternative scenario in which a center portion 43 of the ring-shaped surface 35 of the header cap 9 extends at an angle with respect to the opposing ring-shaped surface 33 of the header base 7. However, in such alternative scenario, both, the outer surface 33 of the header base 7 as well as the inner surface 35 of the header cap 9 comprise heavily curved sections 45. Such sections 45 may form fulcrums upon bending the tine 25, thereby inducing increased local mechanical stress within the tine 25.

[0070] To further expand on the disclosure, the matrix represented in Fig. 7 highlights how tine header engagement impacts a capacity to reduce fatigue within the tines 25. Each row within the matrix includes (at left) a depiction of the tine / header baseline state (i.e., subject to “no deflection”). The highlighted datums within each of the baseline state depictions represent the locations where the tine first emerges from the surrounding header assembly 5. Further

[0071] 23.148P-WO / 11.12.2025 right within each of the rows of the matrix, tine deformations are illustrated for different surrounding header designs (i.e., A, B, and C) subject to small, medium, and large tine deflections. Both, deflections to the right and deflections to the left are represented. For the small, medium, and large deflection example illustrations within each row of the matrix, additional demarked arrows 47 are presented that point to locations along the tine 25 that are furthest from the datum where tine / header contact occurs.

[0072] With an understanding of the meaning of the locations pointed to by the demarked arrows 47, a full set of such locations (either via simulation or empirically) can be generated in response to tine deformation for any given tine / header design and, in turn, plots of the type shown in Fig. 8 can be generated. This type of plot readily highlights distinct attributes of the different clamping conditions associated with the example A, B, and C designs.

[0073] For the A design, the demarked arrows 47 essentially stay on top of the baseline state’s datum, until so much deflection is applied that the “tip” of the tine contacts the surrounding header (not shown in the matrix depiction). Long-dashed lines in the plot in Fig. 8 show this holding on the datum for the A design (i.e., a long horizontal line) until a sudden discontinuity (i.e., vertical jump) occurs. A mirrored long-dashed line may be seen within the plot about the deflection-free state stemming from the symmetric clamping conditions in the A design.

[0074] For the preferred B design, the surrounding tine header clamping / engagement slowly engages with the tine 25 subject to applied deflections. Whether deflected to the right or the left, this interaction within the design provides a smooth response as shown in the plot in Fig. 8 using a solid line. This smooth response is nominally free of any discontinuities and to the right or left of the origin / datum can be thought of as essentially a function of the applied deflection - i.e., f(applied deflection).

[0075] For the C design, an asymmetric response may be seen when deflected to the right vs. the left. Deflection to the right first causes an initial jump in the plot to a point away from the datum which stems from the new fulcrum introduced by the wall-like geometries on the right side of the clamping feature. Akin to design A, a long stretch may be seen within the plot

[0076] 23.148P-WO / 11.12.2025 where applied deflections do little to move the point until suddenly, subject to grotesque deformations, the tip of the tine 25 engages with the header introducing a second discontinuity. For deflections to the left, the C design shows some function-like interactions but still induces a discontinuity where the furthest afield tine / header contact jumps from the datum.

[0077] In best case design embodiments, the header geometries of the header base 7 and header cap 9 that clamp / retain the tines 25 will generate plots of the type provided in Fig. 8 where curves within present a general (if not complete lack) of discontinuities (i.e., as is exemplarily demonstrated by the “B” curves within Fig.8). Realization of such embodiments can be iteratively developed in simulation and / or empirical forms by “tweaking” designs and subsequently “grading” them using the noted plotting scheme.

[0078] Tine clamping that provides a gradual and smooth encroachment into the permissible range of held tine deflection offers best avenues for success in promoting tine service longevity. Typically, such gradual encroachment will stem from the incorporation of convex geometric clamping topologies. Preferred clamping topologies will likely too be free of geometric discontinuities and will often present surfaces capable of being represented by functions that are continuously differentiable.

[0079] Finally, some possible characteristics and advantages of embodiments of the present invention shall be described with slightly different wording as follows:

[0080] Implants that rely upon tine-based anchors for stable fixation within patient anatomy are subjected to a multitude of mechanical stresses throughout their product lifetimes. Not only do the procedures required to install the medical devices within the patient’s body introduce stresses, but so too do the sustained, repetitive / periodic motions associated with the Implant’s long-term residence in the body (e.g., subject to the motions of a beating heart, inhaling / exhaling lungs, etc.). Despite these stressors, there is a critical need for Implant anchoring designs to not only support stable / sustained engagements with patient anatomy over long spans of time (often for durations of 10 + / - 5 yrs or more) but also to do so in ways that avoid any affiliated mechanical fatigue fracture.

[0081] 23.148P-WO / 11.12.2025 Embodiments of the present invention present an approach to a design of tine-based anchors that incorporates stress relief notches within the tines themselves, includes in-device tineretention structures that deny / reduce a risk for introducing fulcrums to the tines subject to their motion, and gives a means for partially distributing / redirecting stresses applied to the tines to the surrounding tine-retention structures.

[0082] Implantable devices that rely upon tine-based anchors (e.g., leadless pacemakers) need to remain stably affixed within patient anatomy for the full extent of their product service (i.e., often years) without incurring any problematically inelastic deformation and / or fatigue fracture. This need means that the acute mechanical “abuses” associated with the device installation procedure as well as the chronic “abuses” associated with the device’s long term residence within the patient’s anatomy must be appropriately considered in developing robust tine-based anchor designs.

[0083] The aim is to improve a robustness of tine-based Implant anchors to stresses especially associated with chronic residence within human anatomy. Here the small amplitude, but often repetitive / periodic, motions to which the tines are subjected present risks for latent mechanical failures through fatigue fracture.

[0084] In best embodiments of the inventive solution, the tine-based anchor will likely be constructed of nitinol and employ a ring-like structure from which a multitude of individual tines emerge. This “pronged” tine-based geometric configuration could be cut from tube stock and is then subsequently shaped and heat set into a form where the individual tines have baseline curvatures installed within. Figure 3 highlights this overall architecture.

[0085] To avoid concentrating mechanical stresses at geometric transitions associated with the locations where the individual tines emerge from the baseline ring, rather than employing a simple rounded fillet (as is shown in Figure 4), a preferred embodiment incorporates stressrelief notches (Figure 5). These included stress-relief notches serve to push stress away from the “comers” where the tine and the ring interface, thereby diffusing, smearing, and distributing the stress further into the bulk of the ring so as to mitigate tine fracture risks.

[0086] 23.148P-WO / 11.12.2025 The concept of such inclusions is understood through a “heat map” depiction of Mises stress distributions within geometric transitions. To the best of the inventor’s knowledge, this concept has not been considered in the development of tine-based anchors for implantable medical products. While a variety of stress relief notch geometries might be applied to the context of tine-based medical product anchors, best embodiments nominally include a rounded cut into the ring-like center structure. The tip of such cuts preferentially embodies a semi-circular format that may or may not be extended deeper within the ring as a fingerlike intrusion. An overall width of any individual notches introduced at such transitions would, in best embodiments, likely range between 10-50% of the overall width (i.e., not thickness) of the emergent tine structures. Any intrusions of the stress relief notches that are more than simple semi-circles would, in best embodiments, likely range between 5-50% of the cross-sectional width of the center support ring.

[0087] Alternatively or in addition to modifying the tine / ring transition points using a stress relief notch, preferred embodiments of tine-based anchors will also incorporate appropriate surrounding boundary conditions within the Implant header as part of the mechanisms for retaining the ring / tine architecture. In a possible product assembly of the header that attaches the tine-based anchor to the Implant, a press-fit “sandwiching” process is employed. Figure 2 provides an illustration of this press-fit “sandwiching” process where a set of upper and lower PEEK polymer retention rings forming a header cap and a header base engage bars on the Implant housing to hold the ring / tine anchor within the Implant’s header.

[0088] In preferred embodiments, this PEEK “sandwiching” should present geometries to the tines such that whenever they are subjected to movements, associated especially with implanted conditions, the system avoids introducing any point-like fulcrum to the emergent tine as it flexes.

[0089] Figure 6 aims to highlight this concept by offering a handful of cartoon-like depictions of different “sandwiching” designs for retaining the tines within the Implant’s header. The illustration at left (Figure 6A) shows a worst-case “diving board” condition where stress is concentrated at the location where the tine emerges. Any flexure of the tine (left to right) in

[0090] 23.148P-WO / 11.12.2025 this configuration would impinge maximally on the tine at the location where it exits from the PEEK “sandwich”.

[0091] In the center illustration (Figure 6B) we see, by contrast, a preferred embodiment where left / right flexure of the tine would fully avoid creating a fulcrum (i.e. targeted stress point) on the tine. In this preferred embodiment, the deformation of the tine via flexure causes the surrounding PEEK sandwich to gently and gradually push back against the flexing tine as opposed to pushing in any sort of focused manner at one or more point-like locations along the tine.

[0092] Last Figure 6C demonstrates that an alternative “sandwiching” approach may embody a conceivably suboptimal geometric interface as it may be challenged in avoiding the introduction of mechanical fulcrum-style stress interactions to the emergent tine. If flexed to the right, some points risk introducing point-like stresses to the tine while flexure to the left risks introducing point-like stresses at other points. Notably, stress appears to be smaller than the worst case stress scenario presented in Figure 6A.

[0093] Last, in realizing a preferred embodiment for retaining the tine-based anchor within the Implant’s header there should be flexibilities in deciding where the retention “sandwich” pinches the tine structure. If the tine is pinched on its ring-like portion, then the design depends more heavily on the effectiveness of the stress relief notches to combat risks for fatigue failure. In other words, pinching below the location where the tine emerges from the ring demands that the tine and the stress relief notches (along with any subsequent interfacing with the surrounding retainers subject to realized deflections) take the brunt of the mechanical loading associated with flexure. If, on the other hand, the surrounding header “sandwich” pinches the tine itself, then the stress can be distributed further away from the tine / ring transition point and diffused further into the surrounding PEEK.

[0094] A combination of features listed below highlights critical concepts from the above section that may be essential to the overall invention.

[0095] 23.148P-WO / 11.12.2025 • The incorporation of stress-relief notches at the transition points between the ring and emergent tines in nitinol-based tine anchors relevant to implantable medical products

[0096] • The realization of such stress-relieve notches as semi-circular divots carved into the ring immediately adjacent to each tine as approached from paths parallel to the long axis of the tines

[0097] • The realization of such semi-circular divots where the width of such divots ranges from 10-50% of each adjacent individual tine emergent from the ring

[0098] • The enhancement of such divots by protruding the semicircular shape further into the ring as a finger-like intrusion to depths ranging from 5-50% of the width of the center support ring

[0099] • The use of a press-fit “sandwich” tine retainment element that, subject to tine flexure, avoids the introduction of fulcrums that would concentrate stress at any point along the tine’ s exit path from the Implant header

[0100] • The ability to optionally configure the “sandwich” -based tine retention (via distinct upper and lower “bread” piece designs) to pinch on the tine either below the tine / ring transition point or above the tine / ring transition point

[0101] Technical advantages of embodiments of the invention presented herein compared to known solutions may be as follows:

[0102] • Uses the same manufacturing processes as our presently planned-for-launch leadless pacemaker

[0103] • Avoids necessitating any extension to the overall length or width of the implanted device

[0104] • Potentially extends the viable implanted service times of our products which, for certain devices, would coincidentally permit the delivery of therapy for longer durations

[0105] • Potentially supports improved long-term access to consistently low pacing capture thresholds in pacemakers that leverage tine-based anchoring

[0106] • Lowers the risk for creating loose, freely mobile mechanical materials within the patient which could present concerns for embolism, blockage, and other physiologic complications

[0107] • Lowers the risk for dislodgment of any affiliate devices from their intended anchor location

[0108] 23.148P-WO / 11.12.2025 • Lowers the risk for the sudden cessation of intended therapy administration in cases where an active implantable medical device (AIMD) dislodges from critical electrical interfacing within the anatomy Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0109] 23.148P-WO / 11.12.2025 List of Reference Numerals

[0110] I implantable intracardiac device

[0111] 3 housing

[0112] 5 header assembly

[0113] 7 proximal header base

[0114] 9 distal header cap

[0115] I I tine arrangement

[0116] 13 steroid depot

[0117] 15 distal end face

[0118] 17 feedthrough

[0119] 19 electrode

[0120] 21 insulator

[0121] 23 base ring

[0122] 25 tine

[0123] 27 transition location

[0124] 29 semi-circular tine portion

[0125] 31 straight tine portion

[0126] 33 outer ring-shaped surface at header base

[0127] 35 inner ring-shaped surface at header cap

[0128] 37 fillet

[0129] 39 notch

[0130] 41 divot

[0131] 43 center portion of the ring-shaped surface of the header cap

[0132] 45 heavily curved sections

[0133] 47 demarked arrows

[0134] 23.148P-WO / 11.12.2025

Claims

Claims1. An implantable intracardiac device (1) comprising: a housing (3), and a header assembly (5) attached to an end face of the housing (3), wherein the header assembly (5) comprises a ring-shaped proximal header base (7), a ring-shaped distal header cap (9) and tine arrangement (11) being at least partially interposed between the header base (7) and the header cap (9), wherein the tine arrangement (11) comprises a base ring (23) and at least two elongated tines (25) protruding distally from the base ring (23), wherein the tine arrangement (11) further comprises, at each associated one of the tines (25), two notches (39) extending into the base ring (23) at opposing sides of the associated tine (25), each of the notches (39) being positioned at a transition location (27) between the base ring (23) and the associated tine (25).

2. The implantable intracardiac device (1) of claim 1, wherein the notches (39) are configured as rounded divots (41) carved into the base ring (23).

3. The implantable intracardiac device (1) of claim 2, wherein the rounded divots (41) have a semi-circular contour.

4. The implantable intracardiac device (1) of claim 2, wherein a width of the divots (41) ranges from 10% to 50% of a width of the associated tine (25).

5. The implantable intracardiac device (1) of claim 2, wherein the divots (41) protrude into the base ring (23) as a finger-like intrusion to a depth ranging from 5% to 50% of a width of the base ring (23).

6. The implantable intracardiac device (1) of claim 2, wherein the tine arrangement (11) is cut from a tube stock made of biocompatible23.148P-WO / 11.12.2025metal material and subsequently shaped and heat set into a form where each individual tine (25) has a baseline curvature.

7. An implantable intracardiac device (1) comprising: a housing (3), and a header assembly (5) attached to an end face of the housing (3), wherein the header assembly (5) comprises a ring-shaped proximal header base (7), a ring-shaped distal header cap (9) and tine arrangement (11) being at least partially interposed between the header base (7) and the header cap (11), wherein the tine arrangement (11) comprises a base ring (23) and at least two elongate tines (25) protruding distally from the base ring (23), wherein the tine arrangement (11) is sandwiched between an outer ring-shaped surface (33) of the header base (7) and an inner ring-shaped surface (35) of the header cap (9), wherein the header base (7) at its outer ring-shaped surface (33) and the header cap (9) at its inner ring-shaped surface (35) are each rounded and convex such that a distance (D) between the outer ring-shaped surface (33) of the header base (7) and the tine (25) as well as a distance between the inner ring-shaped surface (35) of the header cap (9) and the tine (25) continually increases along a protrusion direction (PD) of the tine (25).

8. The implantable intracardiac device (1) of claim 7, wherein at least one of the outer ring-shaped surface (33) of the header base (7) and the inner ring-shaped surface (35) of the header cap (9) have a clamping topology being free of geometric discontinuities.

9. The implantable intracardiac device (1) of claim 7, wherein at least one of the outer ring-shaped surface (33) of the header base (7) and the inner ring-shaped surface (35) of the header cap (9) have a contour being represented by continuously differentiable functions.

10. The implantable intracardiac device (1) of claim 7, wherein a portion of the tines directly adjacent to such base ring are sandwiched between an outer ring-shaped23.148P-WO / 11.12.2025surface of the header base and an opposing inner ring-shaped surface of the header cap such as to be stably clamped and held between the header base and the header cap.

11. The implantable intracardiac device (1) of claim 7, wherein the tine arrangement (11) further comprises, at each associated one of the tines (25), two notches (39) extending into the base ring (23) at opposing sides of the associated tine (25), each of the notches (39) being positioned at a transition location (27) between the base ring (23) and the associated tine (25).

12. The implantable intracardiac device (1) of claim 11, further comprising at least one of the featured defined in claims 2 to 6.23.148P-WO / 11.12.2025

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