The present invention relates to an electrode head for a cardiac pacemaker electrode or defibrillator electrode.

Prior art and technical background

A conventional intravascular system typically comprises an end piece with a fixing screw for anchoring or fixing in tissue. By way of example, document EP 0 337 035 Bl discloses a device having a securing element at a distal or remote end of a device, wherein a biocompatible or physiologically compatible covering surrounds the fastening element substantially, which covering can dissolve in order to sufficiently expose the fastening element. Explantation that is safe for the patient is not possible with a device of this type. Since it is also unknown how quickly and when the glucose coating will dissolve, the implantation entails risks for the patient.

Document US 8 160 723 B2 discloses a bipolar electrode having a helix screw, wherein different poles are arranged on different tubes which are longitudinally displaceable relative to one another in order to protect the helix screw during insertion into the body.

Document EP 0 929 342 Bl relates to an implantable line having guide means for translating a rotary movement of a conductor cable in a first direction into an axial extension of the tissue anchoring means by means of a predefined distancing from the electrode head means and for translating a rotary movement into an axial retraction of the tissue anchoring means into the electrode head means. Document US 2015/0246223 Al relates to an intracardial guide means having a movable element comprising an anchoring screw, wherein a rotary movement of a guide tube is translated by means of a coupling finger into an axial movement of the movable element.

A disadvantage of such systems is the comparatively complex structure in order to implement implantation and/or explantation that are/is safe for the patient. In addition, the susceptibility to faults during use of such systems can increase with a rising degree of complexity.

With the present invention, an electrode head for a cardiac pacemaker electrode or defibrillator electrode will be provided which can be produced comparatively economically and yet still permits patient-safe operation for the user.

In accordance with the present invention, an electrode head for a cardiac pacemaker electrode or defibrillator electrode is provided, comprising the following elements:

a main body;

a fixing screw, which is securely connected to the main body; and

a protective sleeve, which sits movably on the main body and is engaged with the fixing screw in such a way that the protective sleeve can be displaced in the direction of the main body by means of a rotary movement of the fixing screw.

It has been found that a comparatively economical electrode head which at the same time increases patient safety is provided by means of the multi-part structure consisting of protective sleeve and main body. Patient-safe use is achieved in that the protective sleeve sits movably on the main body in such a way that the protective sleeve can effectively protect the patient against injury caused by the fixing screw both during the implantation and during the explantation. Since the fixing screw and the protective sleeve are engaged in such a way that the protective sleeve can be displaced in the direction of the main body by means of a rotary movement of the fixing screw, an electrode head having a particularly simple structure is provided, with which the protective sleeve nevertheless can be adjusted relatively accurately into one of a number of adjustable positions relative to the main body or the fixing screw. A relatively small number of component parts of simple structure therefore can be used in order to produce the electrode head. The electrode head therefore offers the patient effective protection in a cost-saving way.

In accordance with a preferred embodiment of the present invention, the electrode head is configured as an electrode head for a cardiac pacemaker electrode or defibrillator electrode, wherein the main body is an electrode carrier, for example a carrier for an inner conductor electrode and/or outer conductor electrode. The main body is preferably an overmoulding of the inner conductor electrode (insert part). By way of example, the material of the main body comprises poly ether ether ketone (PEEK). The fixing screw preferably consists of an electrically conductive material and is electrically conductively connected to the inner conductor electrode.

In accordance with a preferred embodiment of the present invention, a "protective sleeve" has at least one elongate hollow form with two ends. A sleeve can have one or more openings, or also even no opening. However, at least one end of the protective sleeve, specifically the distal end of the protective sleeve, is preferably closed off.

In accordance with a preferred embodiment of the present invention, the expression in accordance with which the fixing screw "is securely connected to the main body" means that the fixing screw is also moved together with the main body when the main body is moved relative to the protective sleeve. The fixing screw is therefore fastened or fixed rigidly or substantially rigidly to the main body.

In accordance with a preferred embodiment of the present invention the expression in accordance with which the "protective sleeve sits movably on the main body" means that the protective sleeve and the main body are movably connected to one another.

In accordance with a preferred embodiment of the present invention the term "are engaged" with respect to the protective sleeve and the fixing screw means that the protective sleeve can be displaced in the direction of the main body under the influence of a constraining force. Here, the protective sleeve is engaged with the fixing screw in such a way that the protective sleeve can be displaced in the direction of the main body by means of a rotary movement of the fixing screw. This preferably means that the fixing screw has a guide element which forces the protective sleeve and fixing screw to move relative to one another in a screw-like manner (i.e. in particular that the fixing screw is screwed through the protective sleeve). The fixing screw is preferably the guide element, wherein the protective sleeve has a corresponding counter element. The guide element is particularly preferably part of the fixing screw having a helix shape, and the counter element is an opening in the protective sleeve, through which the fixing screw passes. In addition, the electrode head can have a screw thread, for example between the main body and protective sleeve. However, in accordance with the present invention, a preferred embodiment is one in which the protective sleeve is engaged exclusively with the fixing screw, i.e. exclusively the fixing screw is the guide element (and no additional screw thread is provided between the main body and protective sleeve). This is because a relatively simple structure of the electrode head can be provided as a result. In accordance with a preferred embodiment of the present invention, the term "in the direction of the main body" means that the protective sleeve is movable towards the main body along an axial direction.

In accordance with a particularly preferred embodiment of the present invention the protective sleeve is engaged with the fixing screw in such a way that the protective sleeve can be displaced in a reversible manner in a direction of the main body by means of a rotary movement of the fixing screw. This means that the fixing screw is movable along the direction both towards the main body and away from the main body. This means in particular that the protective sleeve is engaged with the fixing screw in such a way that the protective sleeve (by means of a rotary movement in accordance with a first direction of rotation of the fixing screw) can be displaced along a first direction towards the main body and (by means of a rotary movement in accordance with a second direction of rotation of the fixing screw, opposite the first direction of rotation) is movable away from the main body along a second direction opposite the first direction.

In accordance with a preferred development of the electrode head of the present invention, it is provided that the electrode head can be adjusted into a starting position, in which a main part of the fixing screw is positioned within the protective sleeve, wherein the electrode head can be adjusted into a fixing position, in which a main part of the fixing screw protrudes from the protective sleeve. Since the fixing screw can be positioned selectively inside or outside the protective sleeve, implantation protection and also explantation protection are made possible. The electrode head preferably therefore can be adjusted continuously or discontinuously into one or more positions between the starting position and the fixing position. The adjustment is preferably implemented in that the protective sleeve is displaced in the direction of the main body by means of the rotary movement of the fixing screw.

In accordance with a further preferred development of the electrode head of the present invention, it is provided that the fixing screw, in the starting position, protrudes in part from the protective sleeve. The protruding part of the fixing screw can thus serve as electrical contact element, for example so as to be able to detect heart signals before the fixing screw is screwed into the tissue material.

In accordance with a further preferred development of the electrode head of the present invention, it is provided that the main body and the protective sleeve are displaceable relative to one another. In accordance with a further preferred development of the electrode head of the present invention, it is provided that the main body, on its outer side, has a first sliding surface and the protective sleeve, on its inner side, has a second sliding surface, wherein the two sliding surfaces are in contact with one another in the starting position of the electrode head. The protective sleeve and the main body preferably are displaceable relative to one another, wherein the protective sleeve and the main body for this purpose preferably have sliding surfaces that are in contact with one another. A particularly simple structure of the electrode head can thus be provided, whereby production costs can be saved.

In accordance with a further preferred development of the electrode head of the present invention, it is provided that the protective sleeve has a sheath part, which at least partially surrounds the main body in the fixing position. In accordance with a further preferred development of the electrode head of the present invention, it is provided that the protective sleeve has a termination element at a distal end of the protective sleeve. In accordance with a further preferred development of the electrode head of the present invention, it is provided that the termination element comprises a membrane material. The membrane material is preferably a biocompatible material, for example a collar with steroid.

In accordance with a further preferred development of the electrode head of the present invention, it is provided that the termination element has an opening, in which the fixing screw engages. The rotary movement of the main body by means of which the protective sleeve is displaced relative to the fixing screw along an axial direction can thus be translated in a particularly simple manner.

In accordance with a further preferred development of the electrode head of the present invention it is provided that the electrode head has delimiting elements, which prevent a removal of the protective sleeve from the main body when the delimiting elements are in contact with one another. The delimiting elements can thus further increase patient safety in that an unintentional loss and thus exposure of the fixing screw during the implantation or explantation can be avoided.

In accordance with a further preferred development of the electrode head of the present invention it is provided that the protective sleeve, at its distal end, has a radiopaque marker. In accordance with a further preferred development of the electrode head of the present invention it is provided that the radiopaque marker comprises a radiopaque material. The radiopaque marker is preferably a radiopaque material or an x-ray contrast, which is fastened to the protective sleeve and thus permits a detection of the position of the protective sleeve relative to a tip of the fixing screw. The marker is preferably a discshaped, in particular annular marker, which is arranged between the membrane and the sheath part of the protective sleeve. By way of example, the marker is a platinum disc. In accordance with an alternative embodiment the protective sleeve in particular consists at least partially or wholly of a radiopaque material.

In accordance with a further preferred development of the electrode head of the present invention it is provided that the electrode head has an inner conductor electrode, which is electrically conductively connected to the fixing screw. The fixing screw can thus be used both in order to displace the protective sleeve and in order to receive electrical signals.

A further aspect of the invention relates to a system comprising an electrode head according to an embodiment of the present invention, wherein the main body of the electrode head is connected at the proximal end of the main body to a sheath of the system, wherein the protective sleeve is movable relative to the sheath of the system.

Further advantages and exemplary embodiments of the present invention will become evident from the detailed description and the drawings.

The invention will be explained in greater detail hereinafter on the basis of drawings and exemplary embodiments.

In the drawings:

Fig. 1 shows a schematic view of a system in accordance with an embodiment of the present invention.

Fig. 2 shows a perspective view of an electrode head in accordance with an embodiment of the present invention in a starting position.

Fig. 3 shows a perspective view of the electrode head shown in Figure 2 in a fixing position.

Fig. 4 shows a planar cross-sectional view of the electrode head shown in Figure 2 in the starting position.

Fig. 5 shows a perspective cross-sectional view of the electrode head shown in Figure

2 in the starting position. Fig. 6 shows a planar cross-sectional view of the electrode head shown in Figure 3 in the fixing position.

Fig. 7 shows a perspective cross-sectional view of the electrode head shown in Figure

3 in the fixing position.

Fig. 8 shows a perspective view of the electrode head in accordance with an embodiment of the present invention in a starting position.

Fig. 9 shows a planar cross-sectional view of the electrode head shown in Figure 8 in the starting position.

Fig. 10 shows a perspective cross-sectional view of the electrode head shown in Figure

8 in a fixing position.

Fig. 11 shows a planar operational view of an electrode head in accordance with an embodiment of the present invention in the starting position.

Fig. 12 shows a planar operational view of an electrode head in accordance with an embodiment of the present invention between the starting position and the fixing position.

Fig. 13 shows a planar operational view of an electrode head in accordance with an embodiment of the present invention in the fixing position.

Figure 1 shows a perspective view of a system 1 in accordance with an embodiment of the present invention. The shown system 1 comprises a sheath 20 (for example a hose or a tube of a catheter) and an electrode head 10 attached distally thereto in accordance with an embodiment of the present invention. The electrode head 10 here is an electrode head for a cardiac pacemaker electrode or defibrillator electrode. The electrode head 10 comprises a main body 1 1 and a protective sleeve 13. A fixing screw for anchoring in tissue or fixing to a tissue material of a living being to be treated is also fastened to the main body, although the main part of said fixing screw cannot be seen in the view shown here since it is accommodated inside the protective sleeve 13. Figure 4 shows a fixing screw 12 of this type, the main part of which is positioned inside the protective sleeve 13. The fixing screw 12 is connected here electrically conductively to an inner conductor electrode.

The protective sleeve 13 is movable, in particular slidable relative to the sheath 20 of the system 1. In the embodiment illustrated in Figure 1, the protective sleeve 13 is movable relative to the sheath 20 along the illustrated arrow along an axial direction, such that the fixing screw (depending on the position of the protective sleeve 13 relative to the sheath 20) is arranged selectively inside or outside the protective sleeve 13. The axial movement of the protective sleeve 13 relative to the sheath 20 is caused here by means of a rotary movement of the main body 11, which in turn is brought about depending on an operation of the operating element 30 of the system 1. The operating system 30 is configured in such a way that the main body 11 and the fixing screw 12 are moved jointly relative to the protective sleeve 13 in a screw- like manner depending on an operation of the operating element 30.

The electrode head 10 is also connected to the sheath 20 of the system 1 at the proximal end l ib of the main body 11. The main body 1 1 of the electrode head 10 is movably connected to the sheath 20 of the system 1 , wherein the main body 11 of the electrode head 10 is mounted rotatably relative to the sheath 20. Alternatively, the main body 11 of the electrode head 10 can be fastened to the sheath 20 of the system 1 (i.e. in particular rigidly or substantially rigidly fixed), such that the sheath 20, the main body 11 of the electrode head 10, and the fixing screw 12 are movable (only) jointly relative to the protective sleeve 13. The main body 11, however, is preferably connected movably (rotatably) to the sheath 20 of the system 1, since the sheath 20 as a result does not also have to be co-rotated in the event of a screwing movement of the main body 11. Figure 2 shows a perspective view of an electrode head 10 from Figure 1 in accordance with an embodiment of the present invention in a starting position. The electrode head 1 10 is for example an electrode head 10 for the system 1 shown in Figure 1 , wherein, however, the electrode head 110 can also be provided as an electrode head 110 for another suitable system 1. The electrode head 110 comprises a main body 11, a fixing screw 12, and a protective sleeve 13. The fixing screw is intended for connection to a tissue material, and the protective sleeve 13 is intended to accommodate the fixing screw 12, so as to thus provide implantation protection and/or explantation protection.

The fixing screw 12 is securely connected to the main body 11. Here, the fixing screw 12 is rigidly connected to the main body 11. In Figure 2 the fixing screw is shown in the starting position, in which a main part of the fixing screw 12 is arranged inside the protective sleeve 13 and another part of the fixing screw 12 protrudes partially from the protective sleeve 13. The shown electrode head 110 also comprises a receiving region 1 11, which is intended to accommodate an outer conductor electrode.

The protective sleeve 13 sits movably on the main body 11 and is displaceable along a direction towards the main body 11. The protective sleeve 13 is engaged with the fixing screw 12 in such a way that the protective sleeve 13 is displaceable in the direction of the main body 11 (by means of a rotary movement of the fixing screw 12). This means that in the case of a rotary movement of the fixing screw 12 relative to the protective sleeve 13, the protective sleeve 13 is displaced in the direction of the main body 11 in such a way that the fixing screw 12 is screwed out from the sleeve 13. The protective sleeve 13 is also engaged accordingly with the fixing screw 12 in such a way that the protective sleeve 13, by means of a further rotary movement (opposite the above-mentioned rotary movement) of the fixing screw 12, is displaceable in an opposite direction (i.e. is distanced again from the main body 11 with increasing rotation). This means that in the case of a rotary movement of the fixing screw 12 relative to the protective sleeve 13, the protective sleeve 13 is displaced in the opposite direction in such a way that the fixing screw 12 is screwed again into the sleeve 13. The electrode head 1 10 is adjustable between the starting position and a fixing position. In the starting position a main part of the fixing screw 12 is positioned inside the protective sleeve 13, as is shown in Figure 2. The fixing position is illustrated in Figure 3.

Figure 3 shows a perspective view of the electrode head 110 shown in the starting position in Figure 2 in the fixing position. In the fixing position a main part of the fixing screw 12 protrudes from the protective sleeve 13. The fixing screw 12 protrudes in the fixing position distally from the protective sleeve 13 in axial direction, starting from the protective sleeve 13 (i.e. pointing away from the protective sleeve 13 and the main body 11). Implantation protection and/or explantation protection can thus be provided economically by selective positioning of the fixing screw outside or inside the protective sleeve with a relatively simple structure of the electrode head 110.

The electrode head 110 is reversibly adjustable from a starting position into a fixing position. This means that the electrode head 110 can be transferred from the starting position into the fixing position and also from the starting position back again into the fixing position by moving the main body 11 and the protective sleeve 13 relative to one another in a screw- like manner. The electrode head 110 is accordingly configured in such a way that the electrode head 110 can be transferred from the starting position into the fixing position by rotating the main body 11 relative to the protective sleeve 13 along a screw path in accordance with a first direction of rotation. The electrode head 110 can be transferred from the fixing position back into the starting position by rotating the main body 11 relative to the protective sleeve 13 along the screw path in accordance with a second direction of rotation, which is opposite the first direction of rotation.

By comparing Figures 1 and 2 it is clear that the main body 11 and the protective sleeve 13 are nested one inside the other both in the starting position and in the fixing position. As can be seen in Figure 2, the main body 11 in the starting position protrudes proximally from the protective sleeve 13 at least in part (i.e. the proximal end 1 lb of the main body 11 protrudes from the protective sleeve 13). The electrode head thus comprises at least two parts movable relative to one another, wherein both parts, i.e. the main body 11 and the protective sleeve 13, are displaceable relative to one another. Here, the protective sleeve 13 is formed in such a way that the protective sleeve 13 in the starting position encases at least the fixing screw 12 and in the fixing position encases at least the main body 11 and thus affords reliable implantation and explantation protection. Depending on the relative position between protective sleeve 13 and main body 11, the electrode head 110 thus can be continuously adjusted between the starting and fixing position. So that injuries to the heart valve fibres/vessels can be prevented, the fixing screw 12 should be reliably protected in this way by the protective sleeve 13 during the implantation and explantation.

The main body 11 has an elongate or cylindrical form and in this case is a solid body. The protective sleeve 13 also has an elongate or cylindrical form and has a hollow form or the form of a hollow cylinder.

The protective sleeve 13 accordingly comprises a sheath part 131 and a termination means 132 (or closure means or cover). At a distal end 13a, the protective sleeve 13 comprises the termination means 132, which seals off or closes the protective sleeve 13 at the distal end 13a thereof. By contrast, the protective sleeve 13 at its proximal end 13b has an opening (see Figure 4), into which the main body 11 can be inserted. For this purpose, an outer diameter of the main body 1 1 is preferably smaller than an inner diameter of the protective sleeve 13 in the region of the opening. The closure means 132 is a membrane comprising a biocompatible material.

Figure 4 shows a planar cross-sectional view of the electrode head 110 shown in Figure 2 in the starting position. At its distal end 11a, the outer form of the main body 11 and an inner form of the protective sleeve 13 are adapted to one another. The main body 11, on its outer side, has a sliding surface l id, and the protective sleeve 13, on its inner side, has a further sliding surface 13 d, which are in contact with one another whilst the protective sleeve 13 and the main body 11 are moved relative to one another in a screw- like manner.

In order to avoid a removal of the protective sleeve 13 from the main body 11, and therefore a loss of the protective sleeve 13 during use of the electrode head 110, the electrode head 110 also has delimiting elements 11c, 13c, which delimit a movement of the protective sleeve 13 relative to the main body as soon as the delimiting elements 11c, 13c are in contact with one another. Accordingly, the main body 11 has a first delimiting element 11c and the protective sleeve 13 has a second delimiting element 13c, wherein the first and second delimiting element 11c, 13c in the starting position are in contact with one another or cooperate with one another in such a way that a further distancing of the protective sleeve 13 from the main body 11 is prevented.

The closure means 132 here is also to be considered as a disc-like closure means, which has an outer side 132a and an inner side 132b. The inner side 132b at the same time serves as a stop element, which delimits a movement of the protective sleeve 13 relative to the main body 11 in a proximal direction, i.e. in a direction towards the main body 11 starting from the closure means 132.

The main body 11 is illustrated here as an electrode main body or electrode carrier. The electrode head 110 comprises both an inner conductor electrode 121 and a receiving region 111 for an outer conductor electrode (which itself is not illustrated here). The inner conductor electrode 121 extends through the main body 11 , wherein the fixing screw 12 is electrically conductively connected to the inner conductor electrode 121 or consists of a reshaped end portion of the inner conductor electrode 121. As shown here, the main body 11 is an overmoulding of an electrically conductive material extending in an elongate manner, the fixing screw 12 and the inner conductor electrode 121 being formed (in one piece) from said material. The receiving region 11 1 is arranged at the proximal end 1 lb of the main body. The outer conductor electrode can be mounted externally on the electrode main body 11. By way of example, the outer conductor electrode is a ring electrode.

Figure 5 shows a prospective cross-sectional view of the electrode head 110 shown in the starting position in Figure 2. The main body 11, the fixing screw 12, and the protective sleeve 13 cooperate in such a way that the screw- like movement of the fixing screw 12 relative to the protective sleeve 13 is brought about depending on a movement of the main body 11 relative to the protective sleeve 13. The fixing screw 12 acts here as a guide element 12, which cooperates with the closure means 132 of the protective sleeve in such a way that the main body 11 and the protective sleeve 13 are movable relative to one another along a screw path in accordance with the form of the fixing screw 12, which in this case corresponds to a helix or screw form. During use, the protective sleeve 13 is pressed by means of its membrane side 132a against a tissue material, such that the protective sleeve 13 is substantially fixed. If the main body 11 is rotated in this position with the fixing screw 12 fastened thereto, the fixing screw 12 thus penetrates into the tissue material, whereby the main body 11 and the fixing screw 12 are moved relative to the (fixed) protective sleeve 13 along a screw path.

Figure 6 shows a planar cross-sectional view of the electrode head 110 shown in Figure 3 in the fixing position. Here, a main part of the fixing screw 12 is screwed out from the protective sleeve 13. The delimiting elements 11c, 13c are distanced from one another in the fixing position. By contrast, a further displacement of the protective sleeve 13 in the direction of the main body 11 (i.e. to the right in the drawing plane) is prevented by the cover 132 contacting the distal end 1 la of the main body 11. Figure 7 shows a perspective cross-sectional view of the electrode head 110 shown in Figure 3 in the fixing position.

Figure 8 shows a perspective view of an electrode head 210 in accordance with an embodiment of the present invention in a starting position. The protective sleeve 13, at its distal end 13a, has an x-ray marker 133 (x-ray contrast) for detecting a position of the marker 133 relative to the fixing screw 12. Here, the marker 133 is an annular platinum disc. The marker 133 is arranged at a distal end 13a of the protective sleeve 13 between the closure element 132 and a sheath part 131 or housing main body 131 of the protective sleeve 13. The marker 133 is preferably a platinum disc. It is thus possible that the screwed position or the screwed state is identified by detection of the marker 133.

Figure 9 shows a planar cross-sectional view of the electrode head 210 shown in Figure 8 in the starting position, and Figure 10 shows a perspective view of the electrode head 210. The detection of the position of the marker 133 relative to an end piece 12a of the fixing screw 12 enables the mapping of signals in that the screwed state of the electrode device 210 is made visible in the x-ray image.

Figures 11 to 13 show planar operational views of an electrode head 310 in accordance with an embodiment of the present invention with different relative positions between the protective sleeve 13 and main body 1 1. In Figure 1 1 the electrode head 310 is shown in the starting position, in which the fixing screw 12 protrudes from the distal end 13a of the protective sleeve 13 by a predefined length Lo. This means that the marker 133 and the end piece 12a or the tip 12a of the fixing screw 12 are distanced by the spacing Lo. In Figure 12 the electrode head 310 is shown in a position between the starting position and the fixing position, in which the fixing screw 12 protrudes from the distal end 13a of the protective sleeve 13 by a fixing length Li . This means that the marker 133 and the tip 12a of the fixing screw 12 are distanced by the spacing Li . In Figure 13 the electrode head 310 is shown in a position between the starting position and the fixing position, in which the fixing screw 12 protrudes from the distal end 13a of the protective sleeve 13 by a fixing length L ₂ . This means that the marker 133 and the tip 12a of the fixing screw 12 are distanced by the spacing L ₂ .

An exemplary embodiment for use of the electrode head 310 according to an embodiment of the present invention comprises the following steps: In a first method step the electrode head 310 is inserted into a hollow organ of a living being until the electrode head 310 reaches a site of implantation, wherein, during the catheterisation, at least a main part of the fixing screw 12 is accommodated in the protective sleeve 13. In a second method step the distal end 13a of the protective sleeve 13 is clamped between a tissue material and the main body 1 1 of the electrode head 310. In a third method step the main body 1 1 and the protective sleeve 13 are moved relative to one another in a screw- like manner until the fixing screw 12 protrudes from the distal end 13a of the protective sleeve 13 by a fixing length Li, wherein the fixing screw 12 is moved out from the protective sleeve 13 during the screwing movement. As the fixing screw 12 is unscrewed from the protective sleeve 13, it engages with the tissue material and thus anchors or fixes itself thereto.

By way of example, in the case of implantation, the electrode device 310 is fixed by rotation of the entire electrode 310 (set screw principle). During rotation, the free fixing length Lo engages in the tissue material (in the heart muscle) and automatically draws itself in there. Here, the protective sleeve 13 is slid rearwardly as far as the stop (i.e. towards the proximal end 1 lb of the main body 1 1). The head main body 1 1 consists of polyether ether ketone (PEEK) and is not visible under x-ray. In the starting position of the protective cap (which in particular is visible under x-ray), said cap hides the fixing screw 12 in the x-ray image (the fixing screw 12 therefore is not visible in the starting position of the protective cap 13). In the screwed- in or implanted state (fixing position), the protective sleeve 13 is slid rearwardly as far as the stop. The fixing screw 12 protrudes here fully from the protective cap. The fixing screw 12 is visible here in the x-ray image.

In a fourth method step a position of the protective sleeve 13 is detected, and in a fifth method step the fixing length Li is determined depending on the detected position of the protective sleeve 13. In an alternative sixth method step a piece of information based on the fixing length Li is output by an outputting means (a screen) depending on the determined fixing length Li and/or the main body 1 1 and the protective sleeve 13 are/is moved again relative to one another in a screw-like manner until the fixing screw 12 protrudes from the distal end 13a of the protective sleeve 13 by a further fixing length L ₂ . In one or more further method steps a further position of the protective sleeve 13 can optionally be detected. In a seventh method step the electrode head 310 is transferred back again into the starting position by means of a screw-like movement of the main body 1 1 and the protective sleeve 13 relative to one another, wherein the fixing screw 12 is moved into the protective sleeve 13 during the screwing movement. The electrode head 310 can then be repositioned or can be guided out from the hollow organ of the living being.

By way of example, during the explantation the electrode device 310 is screwed out from the tissue material by rotation of the entire electrode. The protective sleeve 13 is fixed during the rotation since it is ingrown. Here, the protective sleeve 13 is slid forwards as far as the stop (i.e. in the proximal direction). The fixing screw 12 is covered again by the protective sleeve 13, and the electrode can be reliably removed from the patient. X-ray visibility of the screwed state of the fixed fixing screw 12 is possible by means of the displaceable protective sleeve 13.

The described order of the method steps can be a chronological and/or logical sequence of the method steps, wherein different chronological sequences and optional repetitions of the method steps are possible. If, by way of example, a fourth and fifth method step are performed chronologically before the third method step, it is provided optionally that the screwing movement is interrupted depending on the determined fixing length Li - for example if it is detected that the determined fixing length Li exceeds a predetermined threshold value.

To summarise, the fixing screw 12 of the electrode device 310 is covered by a protective sleeve 13 at the time of insertion into the patient in order to prevent injuries. When the site of implantation is reached, the fixing screw 12 is screwed into the tissue material (into a heart muscle) by rotation of the entire electrode device 310. Here, the protective sleeve 13 shifts and exposes the fixing screw 12. The screwed state of the fixing screw 12 is identified by the detected position of the protective sleeve 13 in the x-ray image. In the starting position of the protective sleeve 13 the fixing screw 12 protrudes from the protective sleeve 13 by a defined length L ₀ and enables the mapping of signals. In the case of explantation the ingrown and thus fixed protective sleeve 13 is brought into the starting position as the electrode device 310 is unscrewed, thus providing the explantation protection. In contrast to an electric device having a fixing screw covered by a glucose cap, in the case of the electrode head 310 a mapping of the signals is made possible prior to the screwing of the fixing screw 12 into the heart tissue. Here, a user does not have to wait for the glucose cap to dissolve, since explantation protection is provided by the protective sleeve 13. The fixing screw is covered by a displaceable protective sleeve during the implantation, wherein the protective sleeve has an x-ray contrast, such that the screwed state of the fixing screw can be identified in the x-ray via the protective sleeve position. A free length of the fixing screw after the implantation is adjusted via an end stop of the protective, wherein a protective membrane (for example collar with steroid) arranged on the protective sleeve additionally serves as stop face at the tissue material. In the starting position the fixing screw protrudes by a defined length beyond the protective membrane and thus enables the mapping of heart signals before the fixing means is screwed into the tissue. In the case of explantation, the ingrown and thus fixed protective sleeve is brought into the starting position as the electrode is unscrewed, whereby the explantation protection is provided.

Although the invention has been explained on the basis of its preferred embodiment(s), many further amendments and variations can be made, without departing from the scope of the present invention. It is therefore provided that the accompanying claims cover amendments and variations which are contained within the actual scope of the invention.