Implantation arrangement and implantable medical device with tines being partially coated with radiopaque material

Abstract

An implantation arrangement (1) and an implantable medical device (5) such as an implantable leadless pacemaker are described. The implantation arrangement comprises an implantation tool (3) having a catheter (7) with a capsule (9) at its distal end for accommodating the implantable medical device. The implantable medical device comprises a housing (11) and plural elongate tines (13) extending from the housing (11) for fixing the implantable medical device at a patient's tissue. The tines are elastically bendable between a first configuration in which the tines are unstrained and a second configuration in which the tines are strained due to being elastically bent upon the implantable medical device together with its tines being accommodated within the catheter's capsule. Therein, in the second configuration, at least one first portion (15) of each tine (13) is elastically bent from a relaxed geometry into a strained geometry whereas at least one second portion (17) of each tine (13) remains in its relaxed geometry. Specifically, each tine comprises a radiopaque material (19) being applied exclusively to the second portion of the tine.

Description

[0001] IMPLANTATION ARRANGEMENT AND IMPLANTABLE MEDICAL DEVICE WITH TINES BEING PARTIALLY COATED WITH RADIOPAQUE MATERIAL

[0002] The present invention relates to an implantable medical device and an implantation arrangement comprising such medical device.

[0003] Implantable medical devices (IMD) may be implanted at or in a body of a patient e.g. for supporting and / or monitoring physiological functions. 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.

[0004] Generally, the IMD is to be arranged and fixed within the body at a predetermined location in order to enable fulfilling its intended function. For example, the ILP is to be arranged and fixed within the carrier chamber such that its electrode reliably remains in electric contact with cardiac tissue despite any motions of the heart.

[0005] For such purpose, IMDs typically comprise a housing and a fixation mechanism. The housing typically accommodates components such as a controller for controlling functions of the IMD and an energy source such as a battery. The fixation mechanism is configured for correctly and reliably fixing the housing in relation to the patient’s body.

[0006] Generally, during an implantation procedure, an implantation arrangement is used for, on the one hand, introducing the IMD into the patient’s body and forwarding it to an intended implantation site and for, on the other hand, suitably activating the fixation mechanism of the IMD for fixing it at tissue at the implantation site. Such implantation arrangement typically comprises an elongate catheter including a capsule at its distal end, wherein the IMD may be accommodated within the capsule during the implantation procedure and may be ejected from the capsule for fixing it at the implantation site.

[0007] In a common approach, the fixation mechanism is implemented using plural elongate tines extending from the housing of the IMD. Such tines are generally elastically bendable. Accordingly, during the implantation procedure, the IMD may initially be comprised within the capsule of the catheter with the tines at the IMD being arranged in a space saving configuration within the capsule. In such state, the tines are elastically deformed such that they fit into the capsule. Accordingly, in such configuration, the tines are mechanically strained. Upon having reached the intended implantation site, the IMD together with its tines is ejected from the capsule and, accordingly, the pre-strained tines may relax from their previous strained geometry to a relaxed geometry. During such relaxation, distal tips of the tines perform a motion which enables distal end portions of the tines to penetrate and be anchored within the patient’s tissue. For example, tines at an iPL may be anchored with their distal end portions in cardiac tissue within the patient’s heart. Subsequently, a so-called tug test is typically applied. Therein, forces such as pulling forces are applied via the catheter to the IMD and it is checked whether the fixation of the IMD is correctly established. Particularly, it may be checked whether the tines of the fixation mechanism are correctly introduced and held within adjacent tissue.

[0008] During the implantation procedure and, particularly, during the tug test, a position of the IMD and of its components generally has to be observed and monitored. For such purpose, x-ray techniques such as computed tomography are generally used. Therein, at least portions of the IMD and / or of the entire implantation arrangement are visible on x-ray images due to some radiopaque material being comprised therein.

[0009] However, it has been recognized that at least in some cases it may be difficult to correctly check the positioning and fixation of tines at an IMD using x-ray techniques. Particularly, for example a position and / or extension of the tines within cardiac tissue may hardly be visible in x-ray images upon the IMD being implanted into a heart which is continuously beating and which, furthermore, is at least partly “hidden” behind ribs also having some x- ray absorption.

[0010] It is an object of the present invention to provide an implantation arrangement and an implantable medical device which enable improving an implantation procedure. Particularly, it may be an object to improve monitoring the tines at the IMD during the implantation procedure. Furthermore, it may be an object to provide such improvement with high reliability, long-term durability and / or at relatively low costs.

[0011] Such objects 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 implantation arrangement is described. The implantation arrangement includes an implantation tool and an implantable medical device. The implantation tool comprises a catheter having a capsule at its distal end for accommodating the implantable medical device. The implantable medical device comprises a housing and plural elongate tines extending from the housing for fixing the implantable medical device at a patient’s tissue. Therein, the tines are elastically bendable between a first configuration in which the tines are unstrained and a second configuration in which the tines are strained due to being elastically bent upon the implantable medical device together with its tines being accommodated within the catheter’s capsule. Furthermore, in the second configuration, at least one first portion of each tine is elastically bent from a relaxed geometry into a strained geometry whereas at least one second portion of each tine remains in its relaxed geometry. Each tine comprises a radiopaque material being applied exclusively to the second portion of the tine.

[0013] According to a second aspect, an implantable medical device is described. The IMD comprises a housing and plural elongate tines extending from the housing for fixing the implantable medical device at a patient’s tissue. Therein, the tines are elastically bendable between a first configuration in which the tines are unstrained and a second configuration in which the tines are strained. Each tine, in its first configuration, comprises a first portion proximal to the housing, the first portion being strongly curved, and a second portion distal to the housing, the second portion being straight or being less curved than the first portion. Each tine comprises a radiopaque material being applied exclusively to the second portion of the tine.

[0014] 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:

[0015] As indicated further above, it is desirable to monitor a process of fixing an IMD at a patient’ s tissue by suitably visualizing a position and / or motion of tines of a fixation mechanism during such process. For such purpose, it is suggested to provide the tines with a radiopaque material.

[0016] However, it has furthermore been found that the tines generally have to be highly elastically flexible and bendable between different configurations such that the tines may be deformed between a first configuration, in which they are in a relaxed geometry and in which they may be anchored in physiological tissue in a long term stable manner, and a second configuration, in which the IMD together with its tines may be accommodated within the catheter’ s capsule during an initial stage of the implantation process.

[0017] It has been observed that due to such required highly elastic flexibility and the fact that the tines are generally substantially bent between the first and second configuration during the implantation process, problems may occur in cases where the entire tine is made from a radiopaque material or is covered with such radiopaque material along its entire extension. Particularly, it has been observed that radiopaque material coated on top of a core of a tine may tend to locally peel-off and / or crack particularly at portions of the tine which are substantially bent during the implantation procedure, i.e. at portions of the tine which are mainly elastically bent between the strained geometry and the relaxed geometry upon bringing the IMD from its initial stage, i.e. accommodated within the capsule of the catheter; to its final stage, i.e. ejected from the capsule and fixed to the physiological tissue. Accordingly, it is proposed herein to provide the tines such that radiopaque material is applied exclusively to second portions of the tines which generally remain in their relaxed geometry, while first portions remain free from any radiopaque material, such first portions of the tines being substantially bent between their strained geometry and their relaxed geometry upon the entire tine being deformed between its second configuration and its first configuration.

[0018] By limiting the application of the radiopaque material to the second portion of the tine, mechanical strains which would otherwise occur between the highly flexible core of the tine and the typically less flexible coating with the radiopaque material at the first portion upon such first portion being substantially bent may be prevented. Instead, the radiopaque material is only provided in areas of the tine forming the second portion, wherein no or hardly any deformation of the tine occurs in such areas during the implantation process. Accordingly, risks of peeling-off and / or cracks at the radiopaque material may be minimized while still providing substantial x-ray absorption to substantial portions of the tines such as to make them highly visible in x-ray images.

[0019] In the following, possible features of embodiments of the invention and associated possible advantages will be described in more detail.

[0020] The implantation arrangement comprises at least two components, i.e. the implantation tool and the IMD.

[0021] The implantation tool comprises an elongate catheter which may be used for introducing and guiding the IMD along an intended path throughout the patient’s body. For example, the catheter may be introduced into and forwarded along blood vessels towards an intended implantation site. The catheter may generally be bendable, guidable and / or steerable. The catheter may generally comprise a handle at its proximal end for guiding and / or steering its motion. At its distal end, the catheter comprises a capsule in which the IMD may be accommodated during an initial stage of the implantation procedure and from which the IMD may be ejected for finally implanting it at the implantation site. The capsule is generally formed by an enlarged cylindrical portion at the distal end of the catheter. The dimensions and geometry of the capsule are generally adapted such that the IMD together with its tines may be completely accommodated within and enclosed by surrounding walls of the capsule.

[0022] The implantable medical device may be any device which serves for providing a medical function and / or monitoring function and which is adapted and sufficiently small for being implanted into the patient’s body. For example, the medical device may be configured for stimulating and / or monitoring physiological functions. In a specific example, on which a focus is set in the present specification, the IMD may be an implantable leadless pacemaker. The IMD comprises a housing in which components such as a controller, an energy storage, etc. are hermetically enclosed.

[0023] At least at one position of the housing, two or more tines are coupled to the housing and at least portions of such tines extend in a direction away from the housing. Plural tines may be coupled with a common base member such as a ring which may be attached to the housing or to a component such as an electrode protruding from the housing. The tines may extend from the common base member in a symmetrical configuration. Each tine has an elongate shape. That is, the tine generally has a length being multiple tines larger than its width and its thickness. For example, the tine may have a length of the few millimeters such as at least 4 mm, at least 8 mm or even more, whereas a width of the tines is substantially smaller, i.e. e.g. less than 4 mm, less than 3 mm or even less than 2 mm, and a thickness of the tines is even smaller than their width, i.e. e.g. less than 1 mm or less than 0.5 mm.

[0024] Generally, the tine is made with a base material providing the tine with a superior elastic flexibility such that the tine may be deformed between a substantially curved geometry and a straightened geometry. Such bays material is typically a metal or metal alloy. Preferably, the base material has some shape-memory characteristics which allow to provide the tine with a predetermined shape to which it returns upon being temporarily deformed. For example, the tine may be made with nitinol. Particularly, the tines may be made by suitably cutting a sheet material into elongate stripes.

[0025] The tines are provided such that, upon no external forces acting onto the tines, they are in a first configuration in which the tines have a first geometry referred to herein as relaxed geometry. In such first configuration, the tines are unstrained, i.e. substantially no mechanical stresses apply to the tines. However, due to their elastic deformability, the tines may be bent from such first configuration to a second configuration in which the tines have a second geometry referred to herein as strained geometry. In such second configuration, the tines are strained, i.e. substantial mechanical stresses apply at least to portions of the tines due to these portions being substantially bent to give the tines the strained geometry. Particularly, in their second configuration, the tines are bent to a geometry such that they can be accommodated together with the IMD in the catheter’s capsule.

[0026] Particularly, the tines are adapted such that, upon a tine being bent into its second configuration, the tine is not deformed along its entire extension. Instead, substantially only a first portion of the tine is elastically bent from its relaxed geometry to its strained geometry, whereas another second portion of the tine remains in its relaxed geometry, i.e. remains substantially undeformed. Specifically, for including the IMD together with its tines into the catheter’s capsule, each of the tines is deformed such that its first portion is bent from its relaxed geometry into a strained geometry whereas its second portion may remain in the relaxed geometry.

[0027] With such tines having first and second portions, it has been found to be beneficial to apply radiopaque material exclusively to the second portions of the tines. In other words, the first portion of each tine shall remain free from any additionally applied radiopaque material. Expressed differently, the base material of the tine shall be provided with additionally applied radiopaque material only at the second portion of the tine whereas no such material is applied at the first portion of the tine.

[0028] Due to such specific local provision of radiopaque material, a risk of local peel-off and / or cracks of the radiopaque material may be minimized as such radiopaque material is applied only in the second portions of the tines which are not bent or at most bent to a non-essential extend upon the IMD together with its tines being in their second configuration while being accommodated within the catheter’s capsule, whereas the first portions of the tines being substantially bent and therefore being substantially strained in such second configuration remain free from any radiopaque material applied thereto. According to an embodiment, in the first configuration, the first portion of each tine being in its relaxed geometry is curved whereas, in the second configuration, the first portion of each tine being in its strained geometry is straightened.

[0029] In other words, while being unstrained and therefore being in its first configuration, the entire tine including its first and second portions is in its relaxed geometry. Therein, the tine is specifically configured such that, in such relaxed geometry, its first portion is substantially curved. For example, the first portion may extend along a curved semicircle. Specifically, the first portion may be curved with a curvature radius being smaller than an overall length of the tine, particularly being smaller than 2 cm, smaller than 1 cm or even smaller than 5 mm. Compared to such curved first portion, the second portion is straightened, i.e. the second portion is substantially less curved than the first portion or is even completely straight.

[0030] Having such relaxed geometry, the tine may then be deformed into its second configuration in which predominantly only the first portion is bent to its strained geometry whereas the second portion of the tine may remain in its relaxed geometry. Accordingly, upon such bending process, the first portion may be deformed from its bent relaxed geometry into a straightened strained geometry, while the second portion may remain in its straightened relaxed geometry.

[0031] Having such specific relaxed geometry and strained geometry, the tines may beneficially serve for fixing the IMD while also enabling including the IMD together with its tines temporarily in the catheter’s capsule.

[0032] According to an embodiment, in the first configuration, the second portion of each tine is less curved than the first portion. Expressed differently, in its relaxed geometry, the tine is substantially curved in its first portion whereas it is less curved in its second portion.

[0033] Particularly, the second portion of each tine may be straight. Having such relaxed geometry in its first configuration, the tines at the IMD may suitably serve for fixing the IMD for example at adjacent tissue mainly with their first portions being suitably deflected during a fixation procedure while the second portions substantially remaining undeformed during such fixation process.

[0034] According to an embodiment, the first portion of each tine extends proximal to the housing whereas the second portion of each tine extends distally to the housing.

[0035] In other words, the first portion of the tine is arranged closer to the housing or to a common base member attached to the housing than the second portion. Accordingly, upon bending the tine from its first configuration to its second configuration, mainly the proximal first portion is deformed whereas the distal second portion remains substantially in its relaxed geometry.

[0036] According to an embodiment, the radiopaque material is applied to the tine exclusively in an extension length forming less than distal-most 50% of an overall extension length of the tine.

[0037] Expressed differently, upon preparing the tines, radiopaque material is not applied to a proximal portion of each of the tines but only two a distal portion of the tines and particularly only to the distal-most 50%, preferably only to the distal-most 40% or 30%, of an entire length of the tine. The radiopaque material may be applied to such distal-most partial area of the tine such as to fully cover such distal-most area or, alternatively, the radiopaque material may be applied in such partial area only locally, for example in a pattern of stripes and / or dots. Accordingly, only the region close to a cantilevering tip of each tine is provided with the radiopaque material whereas at least a proximal half of the extension of the tine remains without radiopaque material.

[0038] Accordingly, the distal second portion of each of the tines close to their distal tip is clearly visible in x-ray images, therefore enabling a detailed monitoring of the tines’ motion during an implantation procedure, while avoiding radiopaque material at the highly bent proximal first region of the tines and thereby preventing any peel-off or cracks in radiopaque material at such first region.

[0039] According to an embodiment, the radiopaque material is coated onto an outer surface of the tine.

[0040] In other words, the radiopaque material is deposited on top of the outer surface of base material forming the tine. Such coating may be applied using various techniques. For example, the radiopaque material may be applied using electroplating, chemical vapor deposition (CVD), physical vapor deposition (PCV), etc. The coating may be deposited onto the fully processed core of the tine. For example, the coating may be applied directly onto the fully processed and electropolished nitinol components forming the tine via electroplating. Applying the radiopaque material as an outer coating onto a core of the time may be established in a reliable and / or more technically simple manner. Furthermore, the coating of radiopaque material limited to exclusively the second portion of the tine may be simply established using for example specific masking techniques.

[0041] According to an embodiment, the radiopaque material is applied as a layer having a thickness of between 1 pm and 100 pm.

[0042] Expressed differently, the radiopaque material is applied as a coating layer having a minimum thickness of at least 1 pm, preferably at least 5 pm, thereby providing the coating layer with a sufficient x-ray visibility. However, the thickness of such radiopaque layer should generally not exceed 100 pm, preferably 50 pm, thereby, inter-alia, limiting any material consumption. The layer may have a uniform thickness. Alternatively, the thickness of the layer may vary along the length extension of the second portion of the tine.

[0043] According to an embodiment, the radiopaque material is applied as a continuous layer. Expressed differently, there is no radiopaque free area between two areas having a radiopaque layer.

[0044] According to an embodiment, the tines are made with a shape-memorizing base material and the radiopaque material has a higher X-ray absorption than the base material. For example, the tines may be made with nitinol as the base material, particularly as elongate and preformed stripes of a nitinol sheet. The radiopaque material may be any material having substantially higher x-ray absorption than such base material, preferably having an x-ray absorption being at least 50% larger or at least 100% larger than in the base material. For example, the radiopaque material may be gold (Au), platinum (Pt) or tantalum (Ta) and / or alloys, composites or mixtures containing at least one of such material. Alternatively or additionally, further materials such as palladium (Pd), iridium (Ir), osmium (Os), rhenium (Re), tungsten (W), niobium (Nb), and / or alloys, composites or mixtures containing at least one such radiopaque material may be used. As a further alternative, the radiopaque material may be provided as a radiopaque loaded polymer, i.e. a polymer material loaded with radiopaque filler, or a metal-polymer composite, ceramics, combinations thereof and the like.

[0045] It shall be noted that possible features and advantages of embodiments of the invention are described herein partly with respect to an implantation arrangement and partly with respect to an implantable medical device usable in such implantation arrangement. 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.

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

[0047] Fig. 1 shows a cross-sectional view of an implantation arrangement according to an embodiment of the present invention with tines at an implantable medical device being in their bent straightened second configuration.

[0048] Fig. 2 shows a cross-sectional view of an implantable medical device according to an embodiment of the present invention with tines being in their relaxed first configuration. Fig. 3 shows a perspective view of an arrangement of tines for an IMD according to an embodiment of the present invention.

[0049] Fig. 4 shows an enlarged cross-sectional visualization of an area “A” indicated in Fig. 3.

[0050] The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

[0051] Fig. 1 shows an implantation arrangement 1 including an implantation tool 3 and an implantable medical device 5.

[0052] The implantation tool 3 comprises an elongate steerable catheter 7. At its distal end, the catheter 7 comprises an enlarged portion forming a capsule 9 in which the IMD 5 is accommodated. The capsule 9 may form a protector sheath for enclosing and protecting the IMD 5 accommodated therein.

[0053] The IMD 5 comprises a housing 11 in which components such as a controller, a battery, etc. are comprised. In the present example, the IMD 5 is an implantable leadless pacemaker. At one end of the elongate housing 11, the IMD 5 comprises an electrode 29 protruding from the housing 11. Such electrode 29 is electrically connected to the controller comprised within the housing 11 such that electric stimulation pulses generated by the controller may be applied to cardiac tissue via the electrode 29.

[0054] Furthermore, the IMD 5 comprises multiple elongate tines 13 extending from the housing 11. The tines 13 are provided as elongate stripes of a nitinol sheet material having shapememorising characteristics. Plural tines 13 extend from a ring-shaped common base member 31. The plural tines 13 and the base member 31 may form an integral component. The base member 31 is coupled to the housing 11 or to the electrode 29 protruding therefrom. The elongate tines 13 and the electrode 29 may be mounted to the housing via a header. Fig. 1 shows the IMD 5 in a situation in which it is comprised within the capsule 9 in order to be delivered to an implantation site within a patient’s heart. In such situation, the elastically flexible tines 13 are bent from their relaxed first configuration to a strained second configuration in which the group of multiple tines 13 is deformed in a space-saving manner such as to be accommodated within the capsule 9. Therein, each of the tines 13 comprises a first portion 15 which, in such second configuration, is bent from a relaxed geometry, in which the first portion 15 is substantially curved, into a strained geometry, in which the first portion 15 is straightened. Such a first portion 15 of the tines 13 is arranged proximal to the housing 11. In contrast hereto, a second portion 17 of the tines 13 substantially remains in its relaxed geometry, i.e. with a lower curvature than the first portion 15 or even a straight geometry, even in such second configuration. Therein, the second portion 17 is arranged distal to the housing 11.

[0055] Fig. 2 shows the IMD 5 in its unstrained first configuration. Fig. 3 shows a perspective view of an arrangement of multiple tines 13 symmetrically arranged at a common base member 31 in their relaxed first configuration. Fig. 4 shows an enlarged cross-sectional view of a part of a tine 13 as indicated by “A” in Fig. 3. Therein, the first portion 15 of each tine 13 is curved in a semicircular contour whereas the second portion 17 is substantially straight. The second portion 17 extends along the distal -most 50% of an overall extension length of the respective tine 13.

[0056] In order to improve a desired visibility of the IMD 5 and, particularly, of its tines 13 in an x- ray image, each of the tines 13 is provided with radiopaque material 19. The radiopaque material 19 is applied as a coating layer 21 to an outer surface 25 of a core 23 of the tine 13. While the core 23 of the tine 13 comprises a highly elastic and preferably shape-memorizing- based material 27 such as nitinol, the coating layer 21 comprises the radiopaque material 19 having a substantially higher x-ray absorption than the base material 27. For example, the radiopaque material 19 may be applied as an electroplated thin gold layer having a thickness of between 5 pm and 50 pm.

[0057] However, the radiopaque material 19 is not applied along the entire tines 13. Instead, the radiopaque material 19 is applied exclusively to the second portion 17 of the tines 13. Accordingly, upon being deformed between its strained geometry of the second configuration, as shown in Fig. 1, and its relaxed geometry in its first configuration, as shown in Fig. 2, the coating layer 21 of radiopaque material 19 is not submitted to the bending action and the resulting mechanical stresses applied in the first portion 15 of the tines 13. Instead, such coating layer may remain substantially undeformed together with the second portion 17 of the tines 13 substantially remaining in their relaxed straight geometry.

[0058] Finally, some possible characteristics and advantages of embodiments of the present invention shall be described with slightly different wording as follows:

[0059] An objective of the present disclosure is to discuss embodiments that increase radi opacity and significantly enhance the user experience during implantation.

[0060] The preferred embodiment layers a selective coating of a radiopaque material (such as gold, platinum or tantalum), or alloys containing at least one radiopaque material, on the nitinol substrate. Fig. 4 illustrates the coating layering.

[0061] The selective coating region is shown on the tine array. The envisioned solution would use a selective radiopaque material (such as gold, platinum or tantalum), or alloys containing at least one radiopaque material, coated on all, or a portion of, but preferably no more than the straight region of the tips of the tines. This allows for a maximum surface area to be covered, and enables the regions of nitinol that experience high strain during use to be unaffected. The coating would preferably cover no more than the full straight region. The gold coating could be deposited directly onto the fully processed and electropolished nitinol component via electroplating. The coating would be at least 1 pm thick to achieve an adequate increase in radi opacity, but would target 25 pm, but would be no thicker than 100 pm for maximum visibility improvement.

[0062] Possible advantages are, inter alia:

[0063] - Increased patient safety due to higher confidence in secure device placement

[0064] - High strain region of substrate unaffected

[0065] - Header assembly region of substrate unaffected The technology can be applied to other shapes of tines, optimized for placement into other regions of the heart, so long as they stay out of the high strain and header assembly regions. 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.

[0066] List of Reference Numerals

[0067] I implantation arrangement

[0068] 3 implantation tool 5 implantable medical device

[0069] 7 catheter

[0070] 9 capsule

[0071] I I housing

[0072] 13 tine 15 first portion

[0073] 17 second portion

[0074] 19 radiopaque material

[0075] 21 coating layer

[0076] 23 core of the tine 25 outer surface

[0077] 27 base material

[0078] 29 electrode

[0079] 31 base member

Claims

Claims1. An implantation arrangement (1) including: an implantation tool (3) comprising a catheter (7) having a capsule (9) at its distal end for accommodating an implantable medical device (5), and an implantable medical device (5) comprising a housing (11) and plural elongate tines (13) extending from the housing (11) for fixing the implantable medical device (5) at a patient’s tissue, wherein the tines (13) are elastically bendable between a first configuration in which the tines (13) are unstrained and a second configuration in which the tines (13) are strained due to being elastically bent upon the implantable medical device (5) together with its tines (13) being accommodated within the catheter’s capsule (9), wherein, in the second configuration, at least one first portion (15) of each tine (13) is elastically bent from a relaxed geometry into a strained geometry whereas at least one second portion (17) of each tine (13) remains in its relaxed geometry, wherein each tine (13) comprises a radiopaque material (19) being applied exclusively to the second portion (17) of the tine (13).

2. The implantation arrangement () of claim 1, wherein, in the first configuration, the first portion (15) of each tine (13) being in its relaxed geometry is curved whereas, in the second configuration, the first portion (15) of each tine (13) being in its strained geometry is straightened.

3. The implantation arrangement () of claim 1, wherein, in the first configuration, the second portion (17) of each tine (13) is less curved than the first portion (15).

4. The implantation arrangement () of claim 1, wherein the second portion (17) of each tine (13) is straight.

5. The implantation arrangement () of claim 1, wherein the first portion (15) of each tine (13) extends proximal to the housing (11)whereas the second portion (17) of each tine (13) extends distally to the housing (11).

6. The implantation arrangement () of claim 1, wherein the radiopaque material (19) is applied to the tine (13) exclusively in an extension length forming less than distal-most 50% of an overall extension length of the tine (13).

7. The implantation arrangement () of claim 1, wherein the radiopaque material (19) is coated onto an outer surface (25) of the tine (13).

8. The implantation arrangement () of claim 1, wherein the radiopaque material (19) is applied as a layer (21) having a thickness of between 1 pm and 100 pm.

9. The implantation arrangement () of claim 1, wherein the tines (13) are made with a shape-memory base material (27) and wherein the radiopaque material (19) has a higher X-ray absorption than the base material (27).

10. An implantable medical device (5), comprising a housing (11) and plural elongate tines (13) extending from the housing (11) for fixing the implantable medical device (5) at a patient’s tissue, wherein the tines (13) are elastically bendable between a first configuration in which the tines (13) are unstrained and a second configuration in which the tines (13) are strained, wherein each tine (13) in its first configuration comprises a first portion (15) proximal to the housing (11), the first portion (15) being strongly curved, and a second portion (17) distal to the housing (11), the second portion (17) being one of straight and less curved than the first portion (15), wherein each tine (13) comprises a radiopaque material (19) being applied exclusively to the second portion (17) of the tine (13).

11. The implantable device of claim 10, wherein each tine (13) comprises the radiopaque material (19) applied to the tine (13) exclusively in an extension length forming less than distal-most 50% of an overall extension length of the tine (13).

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