The present invention relates to an implantable medical device for implantation into a patient according to the preamble of claim 1.

An implantable medical device of this kind comprises a body, a helical coil configured to engage with tissue at a location of interest, the helical coil being arranged on the body and being movable with respect to the body between a retracted position and an extended position, and an electrode pole for at least one of emitting an electrical stimulation signal and sensing an electrical sense signal.

The implantable medical device may for example be a stimulation device which comprises a generator to be implanted for example subcutaneously at a location remote from the heart. In this case the body is formed for example by a lead extending from the generator into the heart to allow for a stimulation or a sensing of signals at a location of interest within the heart, for example within the right ventricle.

Alternatively, the implantable medical device may have the shape of a leadless stimulation device, such as a leadless pacemaker device. In this case the body is formed by the housing of the leadless pacemaker device, which encapsulates components of the leadless pacemaker device such as a processor, a data memory, a battery and other processing equipment to allow for operation of the leadless pacemaker device in an autarkic manner. The leadless pacemaker device may be implanted directly into the heart and may operate within the heart, for example within the right ventricle of the heart, without requiring any leads for placing an electrode pole at a location of interest within the heart. With common electrode pole arrangements of implantable medical devices, an injection and/or sensing of electrical signals generally is possible at the surface of intra-cardiac tissue, an electrode pole being in contact with intra-cardiac tissue in order to allow a coupling to the tissue. With new approaches for example for providing a stimulation in case of a so-called left bundle block, it may be desired to provide for an excitation in a localized fashion in the region of the so-called left bundle branch, which requires to engage with intra-cardiac tissue in the range of the septum of the heart and to place an electrode pole in the vicinity of the left bundle branch, such that stimulation energy may be specifically injected into the left bundle branch. As this requires a piercing of the septum, there is a general desire to provide for an anchoring of an implantable medical device on intra-cardiac tissue which is easy to establish and allows for an excitation comparatively deep in tissue, e.g. in the context of a left bundle branch pacing.

In particular, when introducing an electrode pole for example arranged on a lead from the right ventricle into the septum in order to reach towards the left bundle branch, the electrode pole must be inserted into the tissue to reach a substantial depth in order to come to lie in the vicinity of the left bundle branch. This comes with the inherent risk that a piercing structure on which the electrode pole is arranged may pierce through the septum and may reach into the left ventricle. In addition, the piercing itself possibly may have a significant impact on tissue.

WO 2008/058265 A2 discloses a cardiac stimulation system and method which allow to deliver a left ventricle stimulator from a right ventricle lead system in the right ventricle chamber, into a right side of the septum at a first location, and transmuscularly from the first location to a second location along the left side of the septum. The left ventricle stimulator is fixed at the second location for transmuscular stimulation of the left ventricular conduction system. A biventricular simulation system further includes a right ventricle stimulator also delivered by the right ventricle lead system to the first location along the right side of the septum for right ventricular stimulation.

US 2009/0276000 A1 discloses a method for delivering physiological pacing by selecting an electrode implant site for sensing cardiac signals, which is in proximity to the hearts intrinsic conduction system. An arrangement of multiple electrodes herein is arranged on a tip of a lead.

US 10,406,370 discloses a device for providing cardiac pacing by multiple electrodes inserted using a single conduit. Acceptable electrodes herein are selected as active based on a predetermined criteria, and cardiac stimulation is provided for multiple chambers of the heart from a single location.

It is an object of the instant invention to provide an implantable medical device which allows for an easy implantation and operation, for example in order to provide for a left bundle branch pacing operation.

Accordingly, the helical coil in the retracted position protrudes from the body by a protruding length such that the helical coil is functional to be brought into engagement with tissue in the retracted position.

The body may extend longitudinally along a longitudinal axis. The body herein may for example form a distal end to be placed on tissue upon implantation of the implantable medical device, the helical coil being arranged on the distal end. In particular, the helical coil may extend from the body generally along the longitudinal axis, the helical coil being helically wound about the longitudinal axis such that the helical coil forms a screw thread allowing to screw the helical coil into tissue. The helical coil hence may pierce tissue, e.g. at the myocard, in order to provide for an anchoring of the implantable medical device on tissue.

The helical coil is arranged on the body and is movable with respect to the body between a retracted position and an extended position. In the retracted position the helical coil is partially received within the body, for example within a chamber of a head element of the body, wherein the helical coil in its retracted position however axially protrudes from the body by a protruding length which is large enough such that the helical coil may be brought into engagement with tissue in its retracted position. This allows, during implantation, to engage the helical coil with tissue in the retracted position by rotating the body and by in this way screwing the helical coil into tissue while the helical coil is held rotationally fixed with respect to the body in its retracted position. Once the helical coil in its retracted position is engaged with tissue, it may be moved with respect to the body while now holding the body fixed, such that the helical coil is caused to further engage with tissue in order to bring the helical coil with the electrode pole arranged thereon into a depth within the tissue allowing for an effective stimulation and/or sensing of signals in the tissue.

The protruding length by which the helical coil protrudes from the body in the retracted position may for example lie in a range between 1 mm and 3 mm, for example between 1.5 mm and 2.5 mm, for example at 1.8 mm. The protruding length is such that the helical coil in its retracted position is usable for engaging with tissue and for coupling the electrode pole to tissue for achieving a stimulation and/or sensing, at least in embodiments of use in which a stimulation and/or sensing may take place at a comparatively small depth within tissue.

In one embodiment, the helical coil is movable from the retracted position to the extended position by an extendible length, the extendible length beneficially being larger than the protruding length. For example, the extendible length lies in a range between 1 mm and 6 mm, for example between 2 mm and 4 mm.

By having the helical coil protrude from the body in the retracted position, in which the helical coil is moved farthest into the body, for example into a chamber of a head element of the body, the helical coil in a first step is to be engaged with tissue by rotating the body with the helical coil held fixed on the body. The helical coil herein is caused to engage with tissue with its (entire) protruding length, until a distal end of the body abuts a tissue surface. Beneficially herein, the distal end of the body is shaped such that the body with its distal end cannot enter and pierce into tissue, such that the body assumes a stable position on the tissue when the helical coil is engaged with the tissue. If it is found that the coupling of the electrode pole to tissue is not sufficient when the helical coil in its retracted position is engaged by the protruding length in tissue, the helical coil in a second step can be moved with respect to the body in order to cause the helical coil to deeper engage with tissue, until the electrode pole is brought into a position in which a reliable, effective coupling to tissue, for example at the left bundle branch or at the HIS bundle, is established.

Because the engagement of the helical coil with tissue takes place in two separate steps, a risk of perforating tissue in particular at the myocard of a patient’s heart is at least reduced. In particular, the protruding length in the retracted position of the helical coil is such that in the retracted position the helical coil may be brought into engagement with tissue, with a minimum risk however of perforating the tissue (for example through the epicard into the pericard, which otherwise may cause a so-called micro-perforation of the myocard).

A further engagement of the helical coil with the tissue by moving the helical coil with respect to the body from its retracted position towards the extended position then takes place in an intended, controlled operation by the physician, wherein the physician may monitor the movement for example electrically by observing a coupling of the electrode pole to the tissue. Once a (sufficient) coupling between the electrode pole and the tissue has been established, the movement of the helical coil with respect to the body is stopped.

Because the body beneficially does not engage with tissue in that it does not pierce into tissue, the position of the body on the tissue is stable once the helical coil is caused to engage with the tissue. In addition, because only the thin structure of the helical coil is caused to engage with tissue, the impact on the tissue is minimized, hence substantially reducing a risk of an excessive damaging of tissue. As also only the helical coil grows into tissue while the body is implanted in the patient, an explantation may become easy, requiring simply to unscrew the helical coil from the tissue.

Because during implantation of the implantable medical device the helical coil with the electrode pole arranged thereon may be moved with respect to the body and hence may be brought into an engagement position in which a particular target area, for example on the septum of the heart, may be targeted, the electrode pole may be brought into a position in which the electrode pole comes to rest in the region of e.g. the left bundle branch and may electrically contact the left bundle branch. In this way a pacing at the left bundle branch may be provided, allowing for a physiological stimulation by achieving a propagation of stimulation signals along the bundle branches of the ventricles at low stimulation thresholds. A left bundle branch stimulation may allow for an easy and reliable implantation and easy stimulation algorithms, in particular not requiring a particular adjustment of AV delays as necessary for example for an HIS bundle pacing. The helical coil may also be used to couple to other tissue regions e.g. in a patient’s heart. For example, the body may be implanted such that the helical coil engages with tissue at the septum of the heart to couple with the HIS bundle to achieve a HIS bundle pacing.

Implantation of the implantable medical device in particular becomes easy because within an implantation procedure the electrode pole may be progressively advanced from the body to approach a depth in which the left bundle branch is located, wherein during implantation a capturing of the left bundle branch may be continuously monitored such that advancement of the electrode pole may be stopped once an electrode of the electrode pole couples with the left bundle branch.

In one embodiment, the helical coil is movable with respect to the body by rotation, such that the helical coil with a helically extending coil body may be screwed into tissue at a location of interest in order to bring the electrode pole arranged on the helical coil into electrical contact with the tissue, in order to for example electrically couple to the left bundle branch at a substantial depth within the tissue.

The helical coil may be continuously movable between the retracted position and the extended position and may be stopped at arbitrary positions in between. Alternatively, different, discrete detent positions may be defined into which the helical coil with the electrode pole arranged thereon can be moved, such that the electrode pole can be brought into one of a multiplicity of different, discrete positions with respect to the body. The helical coil may, in one embodiment, comprise multiple electrode poles. Hence, a coupling to tissue may be achieved by one or multiple of the multiplicity of electrode poles arranged on the helical coil. If multiple electrode poles are present on the helical coil, the electrode poles may be electrically independent from each other such that a stimulation and/or sensing may be performed independently by one or multiple electrode poles. By using multiple electrode poles, one or a subset of the electrode poles may be selected in order to couple to a specific tissue area, in addition to adjusting the position of the electrode pole by mechanically moving the helical coil.

In one embodiment, the body comprises a head element in which the helical coil is received. The head element herein forms a distal end of the body, the head element being designed to abut with tissue when implanting the body in a patient. The helical coil herein, in its retracted position, protrudes distantly from the head element and is axially movable along a longitudinal direction to further extend and protrude from the head element.

Herein, the head element forms a chamber in which the helical coil is received and in which the helical coil is movable. In the retracted position the helical coil is retracted farthest into the chamber. From the retracted position the helical is movable out of the chamber in order to farther protrude from the head element.

In one embodiment the helical coil is rotatable with respect to the head element for moving the helical coil between the retracted position and the extended position. The head element is fixedly arranged on the body and is not movable with respect to the body. By rotating the body hence also the head element is rotated such that the helical coil, when held fixed in its retracted position, may be brought into engagement with tissue by its protruding length. By then rotating the helical coil with respect to the head element the helical coil may be further screwed into tissue in order to move the helical coil deeper into the tissue.

In one embodiment, the helical coil forms a threading and the head element comprises a counter element engaging with the threading such that a rotational movement of the helical coil relative to the head element about a longitudinal axis causes a linear displacement of the helical coil relative to the head element along the longitudinal axis. The helical coil hence is coupled to the head element by means of a screwing mechanism comprising a threading and a counter element. By rotating the threading with respect to the counter element due to a rotational movement of the helical coil with respect to the head element the helical coil may be axially moved with respect to the body such that the helical coil may be brought into engagement with tissue or, for explantation, may be moved out of engagement with the tissue.

In one embodiment, the helical coil comprises an end element and the head element comprises a stop section, the end element and the stop section being configured to abut one another in the retracted position of the helical coil for defining the retracted position of the helical coil with respect to the head element. The stop section hence provides for a stop beyond which the helical coil may not be further retracted into the chamber.

Another stop may be provided in the chamber to define the extended position such that the helical coil may not be moved out of the chamber beyond the extended position.

In one embodiment the implantable medical device comprises a drive shaft received within the body and being connected to the helical coil. For example, the drive shaft may have the shape of a spirally wound coil received in the body and being rotatable within the body. The drive shaft may for example be connected to the helical coil at the end element, wherein by rotating the drive shaft the helical coil may be moved within the head element in order to move the helical coil between its retracted position and its extended position with respect to the body. The drive shaft, in one embodiment, can be operated from a proximal end of the body, which during implantation remains outside of the patient and may be connected to a handpiece comprising an actuator operable by a user to rotate the drive shaft.

In one embodiment, the electrode pole is placed at or formed by a tip of the helical coil. The helical coil may for example be formed from an electrically conducting core which is covered with an electrically insulating coating. The area of the electrode pole herein is left free from the coating such that the electrically conductive core of the helical coil is exposed to the outside at the area of the electrode pole and may come into electric contact with surrounding tissue at the location of the electrode pole.

In another embodiment, the helical coil may be formed from an electrically non-conductive helically extending coil body, on which at least one electrode pole element is placed, in particular in the region of the tip of the helical coil. An electrical conductor herein may be embedded in the helically extending coil body to contact the electrode pole placed at the outside of the helically extending coil body.

In one embodiment, the body is formed by a lead which is connectable to a generator of the implantable medical device. In this case, the generator may be implanted into a patient for example subcutaneously remote from the heart, the lead forming the body extending from the generator into the heart such that the body with the helical coil and the electrode pole arranged thereon is placed in the heart, for example within the right ventricle in order to engage with tissue at the right ventricle. If the helical coil is placed at the distal end of the body, the distal end is to be implanted into the heart to engage with intra-cardiac tissue for anchoring the body with its distal end on tissue within the heart. By engaging with tissue, herein, the electrode pole couples with tissue and hence may be used to at least one of emit an electrical stimulation signal and sense an electrical sense signal.

In another embodiment, the body may be formed by a housing of a leadless pacemaker device. In this case, the implantable medical device is formed as a leadless device, which does not comprise leads extending from a location outside of the heart into the heart for providing for a stimulation and/or sensing within the heart. The housing of the leadless pacemaker device may be placed on tissue with a distal end formed by the housing, the helical coil beneficially being placed on the distal end and engaging with tissue when placing the leadless pacemaker device on tissue with its distal end.

In another aspect, a method for implanting an implantable medical device comprises: causing a helical coil to engage with tissue at a location of interest, the helical coil being arranged on a body of the implantable medical device and being movable with respect to the body between a retracted position and an extended position; and by causing the helical coil to engage with tissue, causing an electrode pole to contact tissue for at least one of emitting an electrical stimulation signals and sensing an electrical sense signal, the electrode pole being arranged on or formed by the helical coil. Herein, said (step of) causing the helical coil to engage with tissue includes: rotating the body with the helical coil held fixed on the body in the retracted position in order to screw the helical coil into tissue, the helical coil in the retracted position protruding from the body by a protruding length such that the helical coil is functional to be brought into engagement with tissue in the retracted position, and subsequently rotating the helical coil with respect to the body in order to screw the helical coil further into tissue.

The advantages and advantageous embodiments described above for the implantable medical device equally apply to the method, such that it shall be referred to the above in this respect. The idea of the invention shall subsequently be described in more detail with reference to the embodiments shown in the figures. Herein:

Fig. 1 shows a schematic view of the human heart, including the Sinotrial node, the Atrioventricular node, the HIS bundle and the left bundle branch and right bundle branch extending from the HIS bundle;

Fig. 2 shows a schematic drawing of the heart with a lead implanted therein;

Fig. 3 shows a schematic drawing of the heart with a leadless stimulation device implanted therein;

Fig. 4 shows an embodiment of an implantable medical device having a body in the shape of a lead and a helical coil arranged on the body; Fig. 5A shows a view of a head element of the body, with the helical coil in a retracted position; Fig. 5B shows the head element, with the helical coil in an extended position;

Fig. 6A shows an enlarged view of the head element with the helical coil in the retracted position;

Fig. 6B shows an enlarged view of the head element with the helical coil in the extended position;

Fig. 7 shows a schematic view of the body with the head element received in a catheter for implanting the body in a patient; and

Fig. 8 shows a view of an embodiment of a helical coil having an electrode pole being formed by an exposed area of a core of the helical coil. Subsequently, embodiments of the invention shall be described in detail with reference to the drawings. In the drawings, like reference numerals designate like structural elements.

It is to be noted that the embodiments are not limiting for the invention, but merely represent illustrative examples.

Fig. 1 shows, in a schematic drawing, the human heart comprising the right atrium RA, the right ventricle RV, the left atrium LA and the left ventricle LV, the so-called sinoatrial node SAN being located in the wall of the right atrium RA, the sinoatrial node SAN being formed by a group of cells having the ability to spontaneously produce an electrical impulse that travels through the heart’s electrical conduction system, thus causing the heart to contract in order to pump blood through the heart. The atrioventricular node AVN serves to coordinate electrical conduction in between the atria and the ventricles and is located at the lower back section of the intra-atrial septum near the opening of the coronary sinus. The so-called HIS bundle H extends from the atrioventricular node AVN, the HIS bundle H being comprised of heart muscle cells specialized for electrical conduction and forming part of the electrical conduction system for transmitting electrical impulses from the atrioventricular node AVN via the so-called right bundle branch RBB around the right ventricle RV and via the left bundle branch LBB around the left ventricle LV.

In the example of Fig. 1, an implantable medical device 1 in the shape of a stimulation device such as a pacemaker device, e.g. a CRT device, is implanted in a patient, the implantable medical device 1 comprising a generator 12 connected to leads 10, 11 extending from the generator 12 through the superior vena V into the patient's heart. By means of the leads 10, 11, electrical signals for providing a pacing action in the heart shall be injected into intra-cardiac tissue potentially at different locations within the heart, and sense signals may be received. In addition, possibly a defibrillation therapy may be performed by an electrode arrangement arranged on one or both of the leads 10, 11.

In an embodiment shown in Fig. 2, a lead 10 is implanted into the heart such that it extends into the right ventricle RV of the heart and, at a distal end 101 of a lead body 100, is arranged on intra-cardiac tissue at the septum M in between the right ventricle RV and the left ventricle LV of the heart. At the distal end 101 herein an anchoring device in the shape of a helical coil 13 is arranged, the helical coil 13 serving to anchor the lead 10 with its body 100 to tissue in particular in the region of the septum M. An implantable medical device 1 as concerned herein may generally be a cardiac stimulation device such as a cardiac pacemaker device. A stimulation device of this kind may comprise a generator 12, as shown in Fig. 1, which may be subcutaneously implanted into a patient at a location remote from the heart, one or multiple leads 10, 11 extending from the generator 12 into the heart for emitting stimulation signals in the heart or for obtaining sense signals at one or multiple locations from the heart. If the implantable medical device 1 is a stimulation device using leads, a lead 10 forms a generally longitudinal, tubular body 100 extending along a longitudinal axis L, as shown in Fig. 2, which reaches into the heart and is anchored at a location of interest for example on the septum M of the heart in the region of the right ventricle RV. In another embodiment, the implantable medical device 1 may be a leadless pacemaker device, which does not comprise leads, but has the shape of a capsule and may be directly implanted into the heart, for example into the right ventricle RV of the heart.

Referring now to Fig. 3, in one embodiment an implantable medical device 1 in the shape of a leadless pacemaker device 15 comprises a body 150 in the shape of a housing which extends longitudinally along a longitudinal axis L and encapsulates components of the leadless pacemaker device 15, such as a processing device, a data memory, a battery, pulse generation circuitry and the like to allow for a stimulation operation immediately within the heart.

In the embodiment of Fig. 3, the body 150 in the shape of the housing of the leadless pacemaker device 15 forms a distal end 151 which is placed on intra-cardiac tissue in the region of the septum M of the heart. An anchoring device in the shape of a helical coil 13 is arranged on the body 150 in the region of the distal end 151 and extends from the distal end 151 generally along the longitudinal axis L.

Referring now to Fig. 4, in the implantable medical device 1 an arrangement of electrode poles 14, 102 is placed on the body 100 in order to provide for an electrical stimulation and/or sensing of signals on tissue, for example at the septum in between the right ventricle and the left ventricle, for example in the vicinity of the left bundle branch LBB. For example, one electrode pole 14 is arranged on or formed by the helical coil 13, which for this is at least partially made of an electrically conductive material or carries one or multiple electrode poles. Another electrode pole 102 may be arranged on the body 100 distally from a distal end 101 of the body 100. The electrode poles 14, 102 may e.g. form a dipole electrically connected to appropriate electrical circuitry within the body 100 and allowing an injection and/or reception of signals into respectively from the tissue region on which the body 100 is placed.

Using the anchoring device in the shape of the helical coil 13 and the electrode pole 14 arranged on or formed by the electrical coil 13, it may be desirous to establish a coupling to tissue regions which are located comparatively deep in the tissue, for example in order to couple the electrode pole 14 on the helical coil 13 to the HIS bundle H or to the left bundle branch LBB.

Referring now to Figs. 5 A, 5B and 6A, 6B, in one embodiment the body 100 comprises a head element 103 forming a chamber 105 in which the helical coil 13 is movable. Within the longitudinally extending body 100, herein, a drive shaft 16 in the shape of a spirally wound coil shaft is received, the drive shaft 16 being connected to the helical coil 13 at an end element 134 establishing a rotationally fixed connection between the drive shaft 16 and the helical coil 13.

The helical coil 13 is helically wound and forms a screw thread 130 which is in threaded engagement with a counter element 104 formed within the chamber 105. By rotating the helical coil 13 within the chamber 105, the helical coil 13 is axially moved along the longitudinal axis L along which the body 100 extends, such that the helical coil 13 may be moved out of the chamber 105 towards an extended position, as it for example is visible from the transition between Figs. 6A and 6B.

In a retracted position, in which the helical coil 13 is farthest retracted into the chamber 105 as shown in Figs. 5 A and 6A, the helical coil 13 is not fully received within the chamber 105, but protrudes from the head element 103 by a protruding length XI, as illustrated in Fig. 6A. The protruding length XI herein is large enough such that the helical coil 13, in its retracted position, is engageable with tissue in order to anchor the body 100 on tissue and bring the electrode pole 14 arranged on or formed by the helical coil 13 into a coupling position within the tissue.

From the retracted position the helical coil 13 is movable, along the longitudinal axis L, to further protrude from the head element 13. The helical coil 13 herein is extendible from the chamber 105 by an extendible length X2, as this is illustrated in Fig. 6B, such that in the extended position the helical coil 13 protrudes from the head element 103 by the sum of the protruding length XI and the extendible length X2. In the retracted position the end element 134 abuts a stop section 106 formed by a bottom of the chamber 105, as this is visible from Fig. 6A. By means of the stop section 106, hence, a stop for the helical coil 13 is formed, the stop defining the retracted position beyond which the helical coil 13 cannot be retracted further into the chamber 105.

Another stop may be formed within the chamber 105 to define the extended position according to Fig. 6B, wherein the stop may for example be formed by the counter element 104 or by another stop element in the vicinity of the distal end 101 of the head element 103.

Because the helical coil 13 protrudes from the head element 103 in its retracted position, a two-step procedure is to be used in order to bring the helical coil 13 into engagement with tissue at a location of interest. In particular, in a first operational step the body 100, after having approached the location of interest, is to be rotated about its longitudinal axis L, while holding the helical coil 13 fixed in its retracted position. By rotating the body 100, hence, the helical coil 13 is rotated together with the body 100 and hence with its protruding length XI is screwed into tissue. Once the helical coil 13 with its protruding length XI is fully engaged with tissue and the head element 103 hence with the distal end 101 formed thereon rests on the tissue, as shown in Fig. 5 A, the helical coil 13 - driven by means of the drive shaft 16 - is rotated with respect to the head element 103 and hence is moved out of the chamber 105, as it is visible in the transition from Figs. 5A to 5B. In this way the helical coil 13 is caused to deeper engage with tissue in order to couple the electrode pole 14 arranged on or formed by the helical coil 13 with a desired tissue region, for example the HIS bundle H, as it is shown in Fig. 5B.

Hence, while in a first operational step the body 10 overall is rotated to screw the distally protruding portion of the helical coil 13 in its retracted position into tissue, in a subsequent, second step the helical coil 13 is moved out of the head element 103 of the body 100 in order to further engage the helical coil 13 with tissue. The second step herein is to be carried out in a conscious, intentional fashion by a physician if the coupling to tissue structures in the retracted position of the helical coil 13 is not yet found sufficient.

The further engagement movement of the helical coil 13 herein may be electrically monitored by observing a coupling of the electrode pole 14 arranged on or formed by the helical coil 13 to a desired tissue region, for example the HIS bundle H or the left bundle branch LBB.

The protruding length XI may for example lie in a range between 1 mm and 3 mm, for example between 1.5 mm and 2.5 mm. The protruding length is functional in order to establish an engagement and potentially a coupling of the electrode pole 14 to tissue.

The extendible length X2, in one embodiment, is larger than the protruding length XI. For example, the extendible length X2 may lie in a range between 1 mm and 3 mm, for example in a range between 2 mm and 4 mm.

Referring now to Fig. 7, for approaching the body 100 towards a location of interest with the helical coil 13 in the retracted position in the head element 103, a catheter device 2 may be used, providing for a sheathing to receive and cover the head element 103 and the protruding portion of the helical coil 13. Once the location of interest is reached, the catheter device 2 is withdrawn in order to expose the protruding length XI of the helical coil 13, which may then be caused to engage with tissue at the location of interest by rotating the body 100 and, subsequently, by moving the helical coil 13 from its retracted position to further protrude from the head element 103.

The helical coil 13 forms a screw thread 130 having a sharp, pointy tip 131 by means of which the helical coil 13 may pierce into tissue. The helical coil 13 herein may be entirely formed from an electrically conductive material and hence may form the electrode pole 14 to electrically couple to tissue, wherein the helical coil 13 may be connected to an electrical conductor for example formed by or received in the drive shaft 16 in order to provide for an electrical connection for the helical coil 13. In another embodiment, shown in Fig. 8, the helical coil 13 may comprise an electrically conductive core 132 which partially is covered by an electrically insulating coating 133. An area of the core 132 which is not covered by the coating 133, for example in a tip region of the helical coil 13, herein is exposed towards the outside and hence forms the electrode pole 14, which may be brought into contact with tissue and hence may electrically couple to the tissue.

By forming a spatially defined electrode pole 14 on the helical coil 13, as shown in Fig. 8, a localized excitation and/or sensing in tissue may be obtained. In addition, an impedance of the electrode pole 14 may be reduced.

The coating 133 may for example be formed as a thin-walled tubing made from an insulating material and receiving the core 132 within. Alternatively, the coating 133 may be applied to the core 132 to form a covering layer, for example made from an electrically insulating coating material, such as a lacquer, an oxide layer or a parylene or polyamide layer.

In yet another embodiment the helical coil 13 may comprise a body of an electrically insulating material, wherein one or multiple discrete electrode pole elements may be arranged on the coil body and may be connected to conductors embedded within the coil body.

The idea of the invention is not limited to the embodiments described above, but may be implemented in an entirely different fashion.

An implantable medical device as described herein may be a stimulation device comprising leads, a body being formed by an electrode lead extending from e.g. a generator of the implantable medical device. In another embodiment the implantable medical device may be a leadless device, such as a leadless pacemaker. By means of a helical coil arrangement as proposed herein a coupling to tissue at larger tissue depths may be established, wherein the helical coil may be extended from a body of the implantable medical device as desired in order to establish a coupling to tissue.

List of Reference Numerals

1 Implantable medical device

10 Lead 100 Lead body

101 Distal end 102 Electrode

103 Head member

104 Counter element 105 Chamber

106 Stop section

11 Lead

12 Generator

13 Helical coil 130 Screw thread

131 End section

132 Core

133 Coating

134 End element 14 Electrode pole

15 Leadless device

150 Body (housing)

151 Distal end

16 Drive shaft (spiral coil) 2 Catheter device

AVN Atrioventricular node

H HIS bundle

L Longitudinal axis

LA Left atrium LBB Left bundle branch LV Left ventricle M Intra-cardiac tissue (myocardium) RA Right atrium RBB Right bundle branch RV Right ventricle SAN Sinoatrial node V Superior vena XI Protruding length X2 Extendible length