Electrode head of an electrode lead and assembly therefore

Abstract

The invention is directed to an assembly for an electrode head of an electrode lead having a coil-shaped inner conductor that has a simple structure and manufacturing method, wherein the assembly comprises • a fixation helix, • a cover sleeve adapted to partially cover the fixation helix, and • a substantially cylindrical fixation component having a distal end and a proximal end with respect to a longitudinal axis, wherein the fixation component comprises • a pin-shaped distal section at its distal end, • a blind hole at its proximal end, and • a reduced diameter section located between the pin-shaped distal section and the proximal end. The invention is further directed to a respective electrode head and electrode lead as well as to the respective manufacturing methods thereof.

Description

[0001] Electrode head of an electrode lead and assembly therefore

[0002] The invention relates to an electrode head of an electrode lead which can be actively fixed in a patient’s target tissue, e.g. within the heart. Such electrode lead is usually used with a medical device such as a cardiac pacemaker or a cardioverter / defibrillator or any combination thereof. In most cases, the medical device is an implantable medical device or a medical device that can be worn by the patient.

[0003] Electrode leads are used with the above-mentioned medical device to conduct electrical energy to the patient’s tissue, e.g. the myocardium, and / or to transmit electrical signals from the patient’s tissue to the implantable device. Accordingly, the electrode lead comprises one or several electrodes at or close to its distal end establishing the electrical connection to the patient’s tissue. At its proximal end, the electrode lead comprises a connector to mechanically and electrically connect the electrode lead to the medical device. The invention relates particularly to an electrode lead which comprises at least two electrical conductors, wherein one inner conductor has a coil shape at its distal end section where it is connected to the electrode head.

[0004] To keep the distal end of the electrode lead in a fixed position in relation to the target tissue, the electrode head often comprises an electrode in form of a fixation helix similar to a miniature corkscrew that can be screwed into and is surrounded by the tissue at its very distal end. The electrode head further provides the possibility that it can be bent at the head or in a short distance behind the head for advancement within the vasculature and to exactly position the fixation helix at the target position. Further, prior art electrode heads have a complex structure with many parts requiring complex joining steps which have been unachievable through automation in manufacturing thus far. Accordingly, it is an object of the present invention to simplify the structure and manufacturing method of the electrode head of an electrode lead as described above.

[0005] The above object is accomplished through an assembly for an electrode head having the features of claim 1, an electrode head having the features of claim 10, an electrode lead having the features of claim 11, a manufacturing method of an assembly for an electrode head having the features of claim 12 as well as a manufacturing method of an electrode head having the features of claim 15.

[0006] In particular, the above object is solved by an assembly for an electrode head of an electrode lead having a coil-shaped inner conductor, wherein the assembly comprises

[0007] • a fixation helix,

[0008] • a cover sleeve adapted to partially cover the fixation helix, and

[0009] • a substantially cylindrical fixation component having a distal end and a proximal end with respect to a longitudinal axis, wherein the fixation component comprises

[0010] • a pin-shaped distal section at its distal end configured for accommodation within as well as for mechanical and electric connection to the fixation helix,

[0011] • a blind hole at its proximal end, wherein the inner diameter and depth of the blind hole is configured to receive the coil-shaped inner conductor such that it can be secured within and electrically connected to the fixation component at the blind hole, and

[0012] • a reduced diameter section located between the pin-shaped distal section and the proximal end, wherein the outer diameter of the reduced diameter section is configured to receive the cover sleeve such that the cover sleeve can be secured and electrically connected to the fixation component within this section.

[0013] The above defined assembly combines and secures the critical elements of the electrode head in relation to each other. Further, the electrode head provides an electrical connection from the coil-shaped inner conductor to the fixation helix and to the cover sleeve to establish the electrical contact to the tissue. The electrode head is located at the distal end of an electrode lead.

[0014] The fixation helix is a helix shaped element (or spiral) that is capable to penetrate into the patient’s tissue. It may be manufactured from a wire that is formed as a helix or spiral. It mechanically fixes the distal end of the electrode lead at a target location. At the same time, it provides an electrical connection to the patient’s tissue for application of stimulating electrical pulses and / or detection of electrical signals. The fixation helix forms one electrode of the electrode lead, if applicable, together with the cover sleeve which is at the same electrical potential as the fixation helix since they are electrically connected. The fixation helix may be a right-handed helix or a left-handed helix. The fixation helix may have a constant or varying pitch over its length in longitudinal direction (into the direction of the longitudinal axis). For example, at its proximal end, the pitch may be reduced compared to the central section such that at the proximal end section the wire of two neighboring turns abut to each other. Further, in one embodiment, the pitch at its distal end may be increased in comparison to the main part of the fixation helix. Centrally (i.e. centrally with regard to its cross section perpendicular to the longitudinal axis), for example, the fixation helix may have an approximately cylindrical through-hole extending in longitudinal direction that is surrounded by the helix-shaped wire forming the fixation helix. In one embodiment, the farthest distal tip of the fixation helix may be sharpened to ease penetration into the patient’s tissue at the target location. The fixation helix may basically be formed as a cylindrical helix or conic helix.

[0015] The generally known coil-shaped inner conductor extends through the electrode lead from the connector to the electrode head and transmits electrical pulses or signals from the connector to the electrode head and / or into the opposite direction. By the fixation component and, if applicable, via an attachment sleeve, it is electrically connected to the fixation helix. The coil-shaped inner conductor is a wire formed as a coil that provides the electrical connection between the electrode head and the conductor and is, at the same time, flexible so that it adapts with the electrode lead to the form of the patient’s vasculature. Further, within the coil-shaped inner conductor, a cylindrical lumen is provided for accommodation of the implantation mandrel.

[0016] The cover sleeve is a hollow-cylindrical element of the electrode head which partly covers the fixation helix at its proximal end and which has a wall thickness w. For example, the fixation helix projects from the distal end of the cover sleeve (if fixed to the fixation component) by at least 1 mm (in longitudinal direction). At its distal end the cover sleeve has a stop surface for the electrode head at the patient’s tissue, wherein the projection length of the fixation helix from the distal end of the cover sleeve determines the penetration depth of the fixation helix into the patient’s tissue. Additionally, the cover sleeve consists of electrically conducting material that is electrically connected to the coil-shaped inner conductor located at the proximal end of the fixation component. Furthermore, in one embodiment, the cover sleeve may support a protecting and electrically isolating layer which may comprise a pharmaceutically active substance.

[0017] The fixation component may have a substantially cylindrical form and a longitudinal axis running in a longitudinal direction corresponding to the longitudinal direction of the full electrode lead. The fixation component may be shaped, for example, such that its greatest outer diameter is realized in its main section. There, the diameter of the fixation component corresponds to the outer diameter of the electrode head minus the layer thickness of an outer electrically isolating layer, e.g. a silicone layer. The fixation component comprises in the following order in longitudinal direction from its distal end to its proximal end the following sections: a pin-shaped distal section for accommodation and fixation of the fixation helix at its outer surface, a reduced diameter section for accommodation and fixation of the cover sleeve, and, maybe partly overlapping with the reduced diameter section, a blind hole at its proximal end (i.e. extending in longitudinal direction into the body of the fixation component from its proximal end) for accommodation and fixation of the coil-shaped inner conductor. In one embodiment, the main section may be located at the fixation component’s proximal end or close to the proximal end, at least partly overlapping with the blind hole. The main section may be located proximal from the reduced diameter section. The reduced diameter section has a diameter d that is smaller than the diameter D of the main section. For example, the diameter d of the reduced diameter section is configured such that it is equal to or smaller than the diameter D of the main section minus 2 times the wall thickness w of the cover sleeve (d < D - 2 • w). In this case, the outer diameter of the assembly within the reduced diameter section (i.e. if the cover sleeve is fixed to the fixation component) is equal to or smaller than (i.e. not greater than) the outer diameter D of the main section of the fixation component. The outer diameter of the reduced diameter section is configured to receive the cover sleeve such that the cover sleeve can be secured and electrically connected to the fixation component within this section. The inner surface of the cover sleeve is attached to the outer surface of the fixation component within the reduced diameter section. Accordingly, in one embodiment, the inner diameter of the cover sleeve is equal to or less than (i.e. not greater than) 0.1 mm plus the outer diameter of the outer diameter of the reduced diameter section. In one embodiment, the outer surface of the cover sleeve and the outer surface of the main section of the fixation component will align (in longitudinal direction) when the cover sleeve is fixed to the fixation component. The pin-shaped distal section may have an outer diameter which is equal to or less than the diameter of inner through hole of the fixation helix. Compared to the diameter of the inner through hole of the fixation helix, the outer diameter of the pin-shaped distal section may be, in one embodiment, not smaller than the diameter of the inner through hole of the fixation helix minus 0.1 mm so that the fixation helix can be electrically and mechanically connected to the fixation component at the pin-shaped distal section. The blind hole has an inner diameter that is dimensioned such that the coil-shaped inner conductor can be introduced and moved within the blind hole. In one embodiment, the blind hole may have a circular cross section. For example, the inner diameter of the blind hole is equal to or smaller than (i.e. not greater than) the outer diameter of the coil-shaped inner conductor plus 0.1 mm (if it is directly fixed to the blind hole) or of the attachment component plus 0.1 mm. Additionally or alternatively, the length 1 (in longitudinal direction) of the blind hole is, for example, at least 0,3mm. Further, in one embodiment, the length 1 of the blind hole is greater than the insertion depth of the attachment sleeve as described below. Accordingly, the inner diameter and depth of the blind hole is configured to receive the coil-shaped inner conductor such that it can be secured within and electrically connected to the fixation component at the blind hole. In one embodiment, the fixation component consists of a biocompatible and electrically conducting material and electrically connects the coil-shaped inner conductor to the fixation helix and to the cover sleeve, if applicable, via the attachment sleeve (description of the attachment sleeve is described below). Of course, the inner diameter of the through-hole of the fixation component is equal to or greater than the outer diameter of the pin-shaped distal section of the fixation component, the inner diameter of the cover sleeve is equal to or greater than the outer diameter of the fixation component in its reduced diameter section and the inner diameter of the blind hole is equal to or greater than the outer diameter of the coil-shaped inner conductor or, if applicable, than the outer diameter of the attachment sleeve (at its distal end).

[0018] The above assembly reduces the number of elements of an electrode head and the number of different used materials compared to prior art designs without impairing the functionality of the electrode head. Additionally, the inventive structure, in particular the above described fixation component being a rigid and electrically conducting element, allows automatable and exact manufacturing of the assembly and thereby of the electrode head since, inter alia, a uniaxial assembly is enabled. The basic structure may be transferred very easily to other electrode head designs by shortening or lengthening the individual elements as required. Further, the number of securing steps, e.g. welding, is reduced. If all connections are provided by welding, this causes improvement of MRI (Magnetic Resonance Imaging) capability (in the electrode head area) since there are significantly fewer welded joints and no connections of different type in the electrode head. Furthermore, the coil-shaped inner conductor is fixed within the blind hole and therefore does not need any additional measures for sealing it in relation to the electrode head. The new structure of the electrode head assembly allows introduction of the implantation mandrel into the coil-shaped inner conductor such that it extends into the blind hole of the fixation component. This means that the bending force at the rigid-flex-transition is distributed differently compared to the prior art, namely it forms a connection extending within the blind hole and thereby into the rigid fixation component. In a prior art electrode head the connection was formed on a shaft. Accordingly, flexibility and flexural fatigue strength of the electrode lead at this transition area is improved. Last but not least, the fixation component has a simple structure having little manufacturing costs. It may, for example, be manufactured as a turned part.

[0019] In one embodiment, the assembly further comprises an attachment sleeve that is already mentioned above, wherein the attachment sleeve is configured to receive the coil-shaped inner conductor such that it can be secured to and electrically connected to the attachment sleeve, wherein the attachment sleeve is configured to be received within the blind hole of the fixation component. Further, the attachment sleeve is configured to be secured and electrically connected to the fixation component at its blind hole. The attachment sleeve has basically the form of a hollow cylinder. The inner diameter of the attachment sleeve is adapted to the outer diameter of the coil-shaped inner conductor and, in one embodiment, equal to or smaller than (i.e. not greater than) 0.1 mm plus the outer diameter of the coilshaped inner conductor, wherein the outer diameter of the coil-shaped inner conductor can vary along the length over which it is accommodated within the attachment sleeve. Additionally, in one embodiment, in the distal section that is intended to be inserted into the blind hole of the fixation component, the outer diameter of the attachment sleeve is equal to or greater than (i.e. not smaller than) the inner diameter of the blind hole minus 0.1 mm. The attachment sleeve eases attachment of the coil-shaped inner conductor to the fixation component. This is because the attachment sleeve has a comparatively small wall thickness. Accordingly, securing the coil-shaped inner conductor to the attachment sleeve is cost- effective and can easily be quality checked. The same applies to the attachment sleeve and its securing to the fixation component. Both is described below in relation to securing by welding in greater detail.

[0020] In one embodiment, the attachment sleeve comprises a stop surface such that it delimits the insertion depth of the attachment sleeve within the blind hole. In one embodiment, the stop surface extends perpendicular to the longitudinal direction and has a flat and ring-shaped form, wherein the stop surface is located proximally to the section of the attachment sleeve that is intended to be accommodated within the blind hole. Additionally, in one embodiment, the attachment sleeve may comprise an undercut for accommodation within an electrically isolating tube at its proximal end, wherein the tube may cover the transition area from the electrode head to the elongated lead section of the electrode lead.

[0021] In one embodiment, the fixation component comprises a first stop surface for positioning of the fixation helix, wherein the first stop surface is located at the proximal end of the pinshaped distal section. In one embodiment, the fixation component comprises a second stop surface for positioning of the cover sleeve, wherein the second stop surface is located at the proximal end of the reduced diameter section. In one embodiment, the blind hole comprises a third stop surface for the implantation mandrel at its distal end. The above-mentioned first to third stop surfaces may, for example, extend in a direction perpendicular to the longitudinal direction. The first to second stop surfaces increase manufacturing accuracy and reduce manufacturing time since the respective element that is intended to be attached to the fixation component next to the respective stop surface can be moved to a well-defined position, namely until it abuts against the stop surface. In one embodiment, directly distally from the second stop surface, a circumferential first groove is provided within the reduced diameter section that enables that the cover sleeve may abut directly at the second stop surface of the fixation component. In one embodiment, the reduced diameter section comprises a ring-shaped (circumferential) second groove at its distal end, for example, directly at the first stop surface. The diameter of the fixation component at this second groove may, for example, be basically the same as the outer diameter of the fixation helix. This second groove has the advantage, that the diameter of the fixation component next to the fixation helix (if the fixation helix abuts the first stop surface) is comparable to the outer diameter of the fixation helix so that securing, in particular welding, can be provided with better quality. The third stop surface at the distal end of the blind hole is provided for the implantation mandrel. The third stop surface limits the introduction of the implantation mandrel in distal direction. As it is fully covered by the fixation component, this increases the safety against piercing / penetration of the mandrel.

[0022] In one embodiment, the fixation coil is secured to the pin-shaped distal section by welding and / or the cover sleeve is secured to the reduced diameter section by welding and / or the coilshaped inner conductor is secured to the blind hole or the attachment sleeve by welding and / or, if applicable, the attachment sleeve is secured to the blind hole by welding. For example, the welding steps comprise a welding through the element located at the outside, e.g. the cover sleeve, the attachment sleeve or the fixation component, whose quality may be checked from the outside. In each case, the welding may be a point welding or a seam welding. Welding of the cover sleeve to the fixation component at the second stop surface may, in one embodiment, a welding edge to edge.

[0023] In one embodiment of the assembly, the fixation helix, the fixation component, and / or the cover sleeve consist of a biocompatible and electrically conducting material, e.g. comprising or consisting of at least one material of the group comprising platinum-iridium alloys and titanium alloys.

[0024] The above problem is further solved by an electrode head of an electrode lead, wherein the electrode lead comprises a coil-shaped inner conductor, wherein the electrode head comprises the above described assembly, wherein the cover sleeve and the fixation component are covered at its outer surface by an electrically isolating layer. The electrode head may be located at the distal end of the electrode lead.

[0025] The electrically isolating layer may be a one-piece layer or a layer consisting of at least two tubes arranged one after the other in longitudinal direction. For example, the electrically isolating layer may consist of a distal collar and at least one proximal tube, wherein the collar may comprise a pharmaceutically active material. The pharmaceutically active material may be embedded within a matrix material, for example a silicone material. The at least one proximal tube may consist of silicone. The distal collar may be attached to the proximal tube by a biocompatible and electrically isolating adhesive material, for example a highly viscous, surface-insensitive cyanoacrylate adhesive (as ASI SI 2000).

[0026] The electrode head has the advantages that are discussed with regard to the assembly above. Accordingly, it is referred to the above explanation.

[0027] The above problem is further solved by an electrode lead, wherein the electrode head is located at the distal end of the electrode lead. The electrode head is attached at the distal end of the electrode lead and provides at least one electrode, e.g. by means of the fixation helix and / or the cover sleeve. The electrode head may further comprise at least one second (e.g. ring-shaped) electrode that is located proximally and electrically isolated from the fixation helix and the cover sleeve. The electrode lead comprises a connector at its proximal end for mechanically and electrically connecting the electrode lead to the medical device. Between the electrode head and the connector, the electrode lead comprises a lead (cable) having a coil-shaped inner conductor and a second conductor running parallel to the longitudinal axis but electrically isolated to the coil-shaped inner conductor. Further, the lead comprises an inner lumen for accommodation of the implantation mandrel that may be introduced such that its distal tip can be advanced to the electrode head as described above.

[0028] The above problem is further solved by a manufacturing method of an assembly for an electrode head as described above comprising the following steps:

[0029] • providing the fixation component and the fixation helix,

[0030] • inserting the pin-shaped distal section into the proximal end of the fixation helix and securing the fixation helix to the fixation component at the pin-shaped distal section,

[0031] • introducing the fixation component with the attached fixation helix into the cover sleeve and securing the cover sleeve to the fixation component at the reduced diameter section,

[0032] • introducing the coil-shaped inner conductor into the blind hole and securing the coilshaped inner conductor to the blind hole.

[0033] As indicated above, the manufacturing method is less cost intensive and time consuming than the prior art manufacturing methods (see above). The same applies to the further embodiments of the manufacturing method listed below. In one embodiment of the manufacturing method, prior introducing the coil-shaped inner conductor into the blind hole, the coil-shaped inner conductor is introduced into the attachment sleeve and secured within the attachment sleeve, wherein the attachment sleeve with the attached inner conductor is then inserted into and secured within the blind hole. As indicated above, the attachment sleeve provides more reliable securing of the coil-shaped inner conductor to the electrode head.

[0034] In one embodiment of the manufacturing method, the securing of the fixation coil to the pinshaped distal section and / or of the cover sleeve to the reduced diameter section and / or of the coil-shaped inner conductor to the blind hole or to the attachment sleeve and / or, if applicable, of the attachment sleeve to the blind hole comprises a welding step. The welding is already described above and therefore, it is referred to above explanation for further details.

[0035] In one embodiment of the manufacturing method, additionally, an electrically isolating layer is provided and fixed at the electrode head such that it covers and electrically isolates the cover sleeve and the fixation component at their outer surfaces. For example, the electrically isolating layer is realized using a collar and at least one electrically isolating tube, wherein the collar is accommodated at the outer surface of the distal end of the cover sleeve and the at least one electrically isolating tube proximally from the collar. The collar is electrically isolating, as well. The collar and the electrically isolating tube are fixed to the outer surface of the cover sleeve and the fixation component by a glue or an adhesive.

[0036] The present invention will now be described in further detail with reference to the accompanying schematic drawings, wherein

[0037] Fig. 1 shows an embodiment of an electrode lead in a side view,

[0038] Fig. 2 depicts an electrode head of the electrode lead of Fig. 1 in a longitudinal section,

[0039] Fig. 3 shows the longitudinal section of the electrode head of Fig. 2 with implantation mandrel, Fig. 4 depicts a first manufacturing step of an assembly for the electrode head of Fig. 2 in side view,

[0040] Fig. 5 depicts a second manufacturing step of an assembly for the electrode head of Fig. 2 in a longitudinal section,

[0041] Fig. 6 shows a third manufacturing step of the assembly of the electrode head of Fig. 2 in a longitudinal section,

[0042] Fig. 7 shows a fourth manufacturing step of the assembly of the electrode head of Fig. 2 in a longitudinal section, and

[0043] Fig. 8 shows a fifth manufacturing step of the assembly of the electrode head of Fig. 2 in a longitudinal section.

[0044] The two-wire (or two-pole) electrode lead shown in Fig. 1 and 2 comprises a connector 10 at its proximal end and an electrode head 30 at its distal end. A flexible lead (cable) 20 is located between the connector 10 and electrode head 30, wherein the flexible lead 20 comprises a coil-shaped inner conductor 23, an inner lumen for an implantation mandrel, a second conductor connected to a second electrode 26 and an electrically isolating layer 25 located between the inner conductor 23 and the (outer) second conductor which is connected to the second electrode 26. The inner conductor 23, the inner lumen, the second conductor an the electrically isolating layer 25 extend along the longitudinal axis of the electrode lead from its proximal to its distal end. The electrically isolating layer provides an electrical isolation between the coil-shaped inner conductor 23 and the second conductor. Further, at the distal end of the lead 20, a stiffening tube 24 (e.g. a PTFE tube) is located between the coil-shaped inner conductor 23 and the electrically isolating layer 25 that enables distribution of bending forces at the transition area from the flexible lead 20 to rigid electrode head 30.

[0045] The connector 10 may be, for example, a standard IS-l / DF-1 connector. Alternatively, for a lead with more than two conductors a standard IS-4 / DF-4 connector may be used. The electrode head 30 has a longitudinal axis 31 and comprises a fixation helix 32, a cover sleeve 33 partially covering the fixation helix 32. The fixation helix 32 and the cover sleeve 33 are secured to a fixation component 40 which is explained in more detail below. Within a blind hole 44 of the fixation component 40 the coil-shaped inner connector 23 of the lead is fixed using an attachment sleeve 34.

[0046] The assembly of the electrode head 30 is covered and electrically isolated by a collar 36, a ring-shaped adhesive section 37, a first silicone tube 38, and a second silicone tube 39. These elements 36, 37, 38, 39 provide an electrical isolation of the fixation component 40, the fixation helix 32 and / or the cover sleeve 33 from the second electrode 26. Further, the elements 36, 37, 38, 39 form an electrical insulation layer covering the cover sleeve 33 and / or the fixation component 40 at their outer surface. Further, the collar 36 and the two silicone tubes 38, 39 provide mechanical protection to the inner elements of the electrode head 30. The collar 36 comprises a pharmaceutically active material within its matrix material (e.g. silicone).

[0047] It is shown in Fig. 4 in more detail, that the fixation component 40 comprises several sections in longitudinal direction along the longitudinal axis 31. At its distal end, a pin-shaped distal section 41 is formed. Proximally from the pin-shaped distal section 41 a reduced diameter section 42 is located. Further proximally and adjacently, a main section 43 follows. Further, the cylindrical blind hole 44 extends centrally into the fixation component 40 from the proximal end of the fixation component 40. A first stop surface 46 is located between the pin-shaped distal section 41 and the reduced diameter section 42 and a second stop surface 47 is located between the reduced diameter section 42 and the main section 43. A third stop surface 48 is formed at the distal end of the blind hole 44. The first and second stop surfaces 46, 47 are formed as ring-shaped surfaces running perpendicular to the longitudinal axis 31. The reduced diameter section 42 may comprise a ring-shaped groove 42a at its distal end and / or a ring-shaped groove 42b at its proximal end.

[0048] The fixation component 40 may have, for example, the following dimensions. The outer diameter of the pin-shaped section 41 may be in the range from 0.7 to 0.9 mm, in particular 0.77 mm, the outer diameter d of the reduced diameter section 42 may be in the range from 1.3 to 1.5 mm, in particular 1.41 mm (the inner diameter of the cover sleeve 33 may be, accordingly, in the range of 1.4 to 1.6mm, in particular 1.45 mm), the outer diameter D of the main section 43 may be in the range of 1.6 to 1.8 mm, in particular 1.67 mm, the inner diameter of the blind hole 44 may be in the range of 0.9 to 1.1 mm, in particular 1,0 mm, the depth 1 of the blind hole 44 may be in the range of 1.7 to 2.0 mm, in particular 1.85 mm. Accordingly, the attachment sleeve 34 may have at its distal section an outer diameter in the range of 0.8 to 1.0 mm, in particular 0.92 mm. The inner diameter of the distal section of the attachment sleeve 34 may be, in this embodiment, for example in the range between 0.7 to 0.9 mm, in particular 0.74 mm, and the outer diameter of the coil-shaped inner conductor 23 may be in the range between 0.6 to 0.8 mm, in particular 0.7 mm.

[0049] As one can derive from the structure of the electrode head 30 presented above, the number of elements is relatively small. As a result, the cost of the elements and associated manufacturing expenses are low, as well.

[0050] The depth 1 of the blind hole 44 (i.e. the extension of the blind hole 44 in longitudinal direction) is, for example, 1.85 mm As one can derive from Fig. 3, the implantation mandrel 50 inserted within the coil-shaped inner connector 23 can be pushed forward within the lead 20 and electrode head 30 until it reaches the third stop surface 48 within the blind hole 44. Accordingly, the handling during implantation is simplified. Further, since the coil-shaped inner conductor 23 is introduced such far into the rigid assembly (i.e. the fixation component 40 and the attachment sleeve 34), the reliability of the electrode is significantly increased. This is because the bending load resistance in the rigid-flex transition area (proximal from the attachment sleeve 34) between the electrode head 30 and the lead 20 is increased, as the bending stress in the electrode lead is reduced in this transition area due to the design. Further, the fixation component 40 provides a piercing protection for the implantation mandrel 50.

[0051] In the following, the manufacturing method of the assembly and the electrode head is explained with reference to Fig. 4 to 8.

[0052] In the first step, shown in Fig. 4, the fixation helix 32 and the fixation component 40 is provided. The pin-shaped distal section 41 of the fixation component 40 is then introduced into a through-hole at the proximal end of the fixation helix 32 such that the proximal face of the fixation helix 32 abuts the first stop surface 46. Accordingly, an exact positioning of the fixation helix 32 relative to the fixation component 40 is possible. Then, the fixation helix 32 is welded to the pin-shaped distal section 41 of the fixation component 40, for example by spot welding, wherein the welding area is symbolized in Fig. 5 by star 61. Afterwards, the cover sleeve 33 is slid over this assembly such that the fixation helix 32 and the distal end of the fixation component 40 are accommodated within the cover sleeve 33 (see Fig. 6). Again, the positioning of the cover sleeve 33 is simplified by the second stop surface 47. The cover sleeve 33 is slid over the fixation helix 32 and the fixation component 40 until it abuts the second stop surface 47 as it is shown in Fig. 6. Thereby, the cover sleeve 33 partly covers the fixation helix 32 and the reduced diameter section 42 of the fixation component 40. The width of the second stop surface 47 (in the direction perpendicular to the longitudinal direction) corresponds to the wall thickness of the cover sleeve 33. Hence, the outer surface of the cover sleeve 33 and the outer surface of the main section 43 of the fixation component 40 align (in longitudinal direction). If the cover sleeve 33 is correctly positioned, the cover sleeve 33 will be welded to the reduced diameter section 42 of the fixation component 40, for example by spot welding. The position of the welding area is depicted in Fig. 6 by star 62. The cover sleeve 33 may be welded edge to edge at the very proximal end of the cover sleeve at the second stop surface 47 of the fixation component 40 or further distally. The weld spots can easily be inspected with regard to their quality from the outside after this manufacturing step.

[0053] Further, the coil-shaped inner conductor 23 of the lead 20 is provided and introduced into the attachment sleeve 34 as shown in Fig. 7. For correct positioning, the distal end face of the coil-shaped inner conductor 23 and the distal end face of the attachment sleeve 34 may be aligned which is depicted in Fig. 7, as well. Then, the coil-shaped inner conductor 23 may be welded to the attachment sleeve 34, for example, by spot-welding in an area close to the distal end of the attachment sleeve 34 shown in Fig. 7 by star 63. The coil-shaped inner conductor 23 is then permanently fixed to the attachment sleeve 34.

[0054] The assembly shown in Fig. 7 is then introduced into the blind hole 44 of the fixation component 40. For exact positioning, the attachment sleeve 34 comprises a stop surface 35 (see Fig. 7 and 8) limiting the advancing movement of the coil-shaped inner conductor 23 with attachment sleeve 34 relative to the fixation component 40. When the attachment sleeve 34 abuts by its stop surface 35 to the proximal end surface of the fixation component 40, the fixation component 40 is spot welded to the attachment sleeve 34 in an area depicted in Fig. 8 by star 64. This welding area is located at the proximal end of the fixation component 40. At this end, the fixation component 40 has a reduced diameter that corresponds to the diameter of the attachment sleeve 34 proximal from its stop surface 35. Thereby, welding is more reliable.

[0055] Afterwards the electrically isolating tubes 38, 39 are fixed by using an adhesive as well as the collar 36 with the adhesive ring 37. Then, the electrode head 30 as depicted in Fig. 1 and 2 is completed. For implantation, the mandrel 50 is introduced into the electrode lead and advanced within its inner lumen until it abuts against the third stop surface 48 at the distal end of the blind hole 44 as shown in Fig. 3.

[0056] As one can derive from above explanation, the number of welded connections at the electrode head 30, including the connection of the electrode head 30 to the lead 20, is significantly reduced and welding may be carried out without shielding gas. There is no Titanium-Platinum / Iridium weld joint needed so that the process capability is increased. Additionally, inspection of the weld connections is simplified so that quality control costs are reduced.

[0057] The stop surfaces 35, 46, 47, 48 enable better positioning of the elements of the electrode head 30 so that tolerance chains are reduced. Furthermore, uniaxial mounting is enabled and the dimensions of the elements of the electrode head 30, in particular of fixation component 40, may be easily adapted for different purposes.

Claims

Claims1. An assembly for an electrode head (30) of an electrode lead having a coil-shaped inner conductor (23), wherein the assembly comprises• a fixation helix (32),• a cover sleeve (33) adapted to partially cover the fixation helix (32), and• a substantially cylindrical fixation component (40) having a distal end and a proximal end with respect to a longitudinal axis (31), wherein the fixation component (40) comprises• a pin-shaped distal section (41) at its distal end configured for accommodation within as well as for mechanical and electric connection to the fixation helix (32),• a blind hole (44) at its proximal end, wherein the inner diameter and depth (1) of the blind hole (44) is configured to receive the coil-shaped inner conductor (23) such that it can be secured within and electrically connected to the fixation component (40) at the blind hole (44), and• a reduced diameter section (42) located between the pin-shaped distal section (41) and the proximal end, wherein the outer diameter (d) of the reduced diameter section (42) is configured to receive the cover sleeve (33) such that the cover sleeve (33) can be secured and electrically connected to the fixation component (40) within this section.

2. The assembly of claim 1, wherein the assembly further comprises an attachment sleeve(34), wherein the attachment sleeve (34) is configured to receive the coil-shaped inner conductor (23) such that it can be secured to and electrically connected to the attachment sleeve (34), wherein the attachment sleeve (34) is configured to be received within the blind hole (44) of the fixation component (40) as well as to be secured and electrically connected to the fixation component (40) at its blind hole (44).

3. The assembly of claim 2, wherein the attachment sleeve (34) comprises a stop surface(35) such that it delimits the insertion depth of the attachment sleeve (34) within the blind hole (44).

4. The assembly of any one of the previous claims, wherein the fixation component (40) comprises a first stop surface (46) for positioning of the fixation helix (32), wherein the first stop surface (46) is located at the proximal end of the pin-shaped distal section(41).

5. The assembly of any one of the previous claims, wherein the fixation component (40) comprises a second stop surface (47) for positioning of the cover sleeve (33), wherein the second stop surface (47) is located at the proximal end of the reduced diameter section (42).

6. The assembly of any one of the previous claims, wherein the fixation coil (41) is secured to the pin-shaped distal section (41) by welding and / or wherein the cover sleeve (33) is secured to the reduced diameter section (42) by welding and / or the coilshaped inner conductor (23) is secured to the blind hole (44) or to the attachment sleeve (34) by welding and / or, if applicable, the attachment sleeve (34) is secured to the blind hole (44) by welding.

7. The assembly of any one of the previous claims, wherein at its distal end the blind hole (44) comprises a third stop surface (48) for the implantation mandrel (50).

8. The assembly of any one of the previous claims, wherein the fixation helix (32), the fixation component (40), and / or the cover sleeve (33) consist of a biocompatible and electrically conducting material, e.g. comprising or consisting of at least one material of the group comprising platinum-iridium alloys and titanium alloys.

9. The assembly of any one of the previous claims, wherein the reduced diameter section(42) comprises a ring-shaped groove (42a) at its distal end.

10. An electrode head (30) of an electrode lead comprising a coil-shaped inner conductor (23), wherein the electrode head (30) comprises the assembly of any one of the previous claims, wherein the cover sleeve (33) and the fixation component (40) are covered at their outer surface by an electrically isolating layer (36, 37, 38, 39).

11. An electrode lead comprising an electrode head (30) according to claim 10, wherein the electrode head (30) is located at the distal end of the electrode lead.

12. A manufacturing method of an assembly for an electrode head (30) according to any one of the claims 1 to 9 comprising the following steps:• providing the fixation component (40) and the fixation helix (32),• inserting the pin-shaped distal section (41) into the proximal end of the fixation helix (32) and securing the fixation helix (32) to the fixation component (40) at the pin-shaped distal section (41),• introducing the fixation component (40) with the attached fixation helix (32) into the cover sleeve (33) and securing the cover sleeve (33) to the fixation component (40) at the reduced diameter section (42),• introducing the coil-shaped inner conductor (23) into the blind hole (44) and securing the coil-shaped inner conductor (23) to the blind hole (44).

13. The manufacturing method of claim 12, wherein prior introducing the coil-shaped inner conductor (23) into the blind hole (44), the coil-shaped inner conductor (23) is introduced into the attachment sleeve (34) and secured within the attachment sleeve (34), wherein the attachment sleeve (34) with the attached inner conductor (23) is then inserted into and secured within the blind hole (44).

14. The manufacturing method of any one of the claims 12 to 13, wherein the securing of the fixation coil (32) to the pin-shaped distal section (41) and / or of the cover sleeve (33) to the reduced diameter section (42) and / or of the coil-shaped inner conductor (23) to the blind hole (44) or to the attachment sleeve (34) and / or, if applicable, of the attachment sleeve (34) to the blind hole (44) comprises a welding step.

15. A manufacturing method of an electrode head (30) comprising the steps of the manufacturing method of any one of the claims 12 to 14, wherein an electrically isolating layer (36, 37, 38, 39) is provided and fixed at the electrode head (30) such that it covers and electrically isolates the cover sleeve (33) and the fixation component (40) at their outer surfaces.

Images