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 first anchoring element arranged on the body and having a first electrode for at least one of emitting an electrical stimulation signal and sensing an electrical sense signal, and a second anchoring element arranged on the body having a second electrode for at least one of emitting an electrical stimulation signal and sensing an electrical sense signal.

The implantable medical device may for example 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 at a location of interest within the heart.

Alternatively, the implantable medical device may 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. With common electrode arrangements of implantable medical devices, an injection of stimulation signals generally is possible at the surface of intra-cardiac tissue, an electrode being in contact with intra-cardiac tissue in order to allow a injection of stimulation energy into 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 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 a spatially differentiated excitation of tissue, in particular in the context of a left bundle branch pacing.

In particular, when introducing an electrode for example arranged on a lead from the right ventricle into the septum in order to reach towards the left bundle branch, the electrode 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 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 and may even destroy tissue. In addition, when placing an electrode on the septum to reach to the left bundle branch, there is a risk of dislocation, for example when the electrode is arranged on an anchoring device in the shape of a screw, such that an electrical coupling in between the electrode and the left bundle branch may deteriorate over time due to for example a displacement of the screw, potentially leading to a capture loss.

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, in particular in order to provide for a left bundle branch pacing operation.

This object is achieved for means of an implantable medical device comprising the features of claim 1.

Accordingly, the first electrode is arranged at a first height with respect to the body, and the second electrode is arranged at a second height with respect to the body, wherein the first height is different than the second height.

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 first anchoring element and the second anchoring element being arranged on and extending from the distal end. In particular, the first anchoring element and the second anchoring element may extend from the body generally along the longitudinal axis, the first anchoring element and the second anchoring element protruding from the body in order to allow a piercing of tissue by means of the first anchoring element and the second anchoring element in order to provide for an anchoring of the implantable medical device on tissue.

In one embodiment, the body may be 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 electrodes arranged thereon are placed in the heart, for example within the right ventricle in order to engage with tissue at the right ventricle. If the first anchoring element and the second anchoring element are 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 first electrode arranged on the first anchoring element and the second electrode arranged on the second anchoring element comes to engage with tissue and hence may be used to at least one of emitting an electrical stimulation signal and sensing 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 first anchoring element with the first electrode arranged thereon and the second anchoring element with the second electrode arranged thereon beneficially being placed on the distal end and engaging with tissue when placing the leadless pacemaker device on tissue with its distal end.

In one embodiment, at least one of the first anchoring element and the second anchoring element is formed by a flexibly bendable tine. A tine of this kind may in particular be arranged on the body with a first end and may extend from the body in a distal direction to form an apex and to bend backwards generally opposite to the distal direction to form a hook. When being placed on tissue, the tine may engage with tissue such that the apex is placed within tissue, a second, far end of the tine for example being placed outside of the tissue such that the tine forms a hook to anchor the implantable medical device to tissue at a location of interest. By flexibly bending the tine each anchoring element may be brought into engagement with tissue, wherein upon deployment each tine flexibly deforms and resets towards its original, unbent shape in order to form a hook for anchoring the implantable medical device to the tissue.

In one embodiment, both anchoring elements are formed by a tine. Each anchoring element herein carries an electrode, which in an implanted state comes to rest within tissue to electrically contact with tissue.

In one embodiment, the first anchoring element comprises a first apex and the second anchoring element comprises a second apex. For each anchoring element the apex denotes that portion of the anchoring element which is farthest removed from the body (along a direction of extension along which the anchoring element extends from the body and which may generally point along the longitudinal axis along which the body extends). The first electrode of the first anchoring element herein may be placed at the first apex, and the second electrode of the second anchoring element may be placed at the second apex. The first apex and the second apex herein may be placed at different heights with respect to the body, such that the anchoring elements extend, when being placed within tissue, into different depths and hence may engage with different tissue cells at different depths for example within the septum of the heart.

Because the electrodes are placed at different heights with respect to the body and hence may be placed within different depths within tissue, using the electrodes an excitation at different depths may be provided. The implantable medical device herein may comprise two or more anchoring elements, each carrying one or multiple electrodes. By selecting one or multiple of the electrodes for at least one of emitting an electrical stimulation signal and sensing an electrical sense signal, an excitation or sensing for example at the left bundle branch in a spatially differentiated manner may be achieved, in that one or multiple electrodes may be selected which are closest and best coupled to the left bundle branch. Because the implantable medical device may be implanted into the patient's heart such that at least one of the first anchoring element with the first electrode arranged thereon and the second anchoring element with the second electrode arranged thereon comes to rest in the region of the left bundle branch and may electrically contact the left bundle branch, 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.

Implantation of the implantable medical device in particular becomes easy because for the implantation it is not required to place each and every anchoring element in the immediate vicinity of the left bundle branch. It may be sufficient to generally implant the implantable medical device such that the body of the lead or the leadless pacemaker device is placed on the septum in the general region of the left bundle branch, wherein after implantation and during operation one or multiple electrodes of the anchoring elements may be selected in order to establish a spatially differentiated, effective coupling to the left bundle branch. Hence, implantation may be easy, and operation may be reliable. In addition, even when a dislocation of one or multiple anchoring elements occurs, this may not have an impact on the operation of the implantable medical device, as a different set of electrodes may be used for excitation or sensing in case of a capture loss, such that operation may be modified and adapted over the operative lifespan of the implantable medical device.

In one embodiment, at least one of the first anchoring element and the second anchoring element comprises an electrically conductive core. The core may be made from a nickel titanium alloy material (such as nitinol), wherein an electrically insulating coating may be placed on the outside of the core to electrically insulate the core towards the outside. In order to provide for an electrode on the respective anchoring element, herein, the coating may be interrupted at one or multiple locations in order to expose the core towards the outside, such that the core at one or multiple locations may come into electrical contact with surrounding tissue, hence forming one or multiple electrodes on the respective anchoring elements.

If electrodes shall be operated electrically independent of each other, the respective anchoring element may comprise multiple layers, wherein electrically conductive layers and electrically insulating layers may alternate. Different electrodes may be formed in this way on an anchoring element at different locations, wherein each electrode is associated with a particular layer of the anchoring element. In another embodiment, at least one of the first anchoring element and the second anchoring element may have a body formed from a (electrically non-conductive) plastics material, wherein one or multiple electrodes may be placed on an outer surface of the body. Conductors herein may be embedded in the inner body to electrically contact the electrodes on the outside of the body.

In one embodiment, the implantable medical device comprises a processing device configured to control operation of the first electrode and the second electrode for at least one of emitting an electrical stimulation signal and sensing an electrical sense signal using at least one of said first electrode and said second electrode. The processing device may be part of a generator, in case the body is formed by a lead extending from the generator. Alternatively, the processing device may be part of a leadless pacemaker device forming the implantable medical device. The processing device may control operation of the implantable medical device, in that for example one or multiple electrodes are selected in order to capture the left bundle branch and to provide for a stimulation or sensing at the left bundle branch using one or multiple electrodes of one or multiple anchoring elements.

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 view of another embodiment with an implantable medical device in the shape of a leadless pacemaker device implanted in the right ventricle of the heart;

Fig. 4 shows a view of yet another embodiment of an implantable medical device in the shape of a leadless pacemaker device; and

Fig. 5 shows a view of an anchoring element in the shape of a tine having an electrically conductive core covered by a coating and exposed, at an apex, to the outside to form an electrode on the anchoring element. 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. From the atrioventricular node AVN the so-called HIS bundle H is extending, 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 embodiment of Fig. 1, an implantable medical device 1 in the shape of a stimulation device, such as 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, 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 anchoring elements 13, 14 in the shape of tines are arranged, the anchoring elements 13, 14 serving to anchor the lead 10 with its body 100 to tissue in particular in the region of the septum M within the heart. In addition, electrodes are placed on the anchoring elements 13, 14, as shall be described in further detail according to the embodiments of Figs. 3 to 5 below.

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 16, 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 range of the septum M of the heart, anchoring elements 13, 14 being arranged on the body 150 in the region of the distal end 151 and extending from the distal end 151 generally along the longitudinal axis L.

In the shown embodiment, the anchoring elements 13, 14 are formed by flexibly bendable tines which at one end 133, 143 are connected to the body 150 of the leadless pacemaker device 15 to extend from the body 150 to form an apex 132, 142 and to then bend backwards to exit from tissue with far ends 130, 140. The anchoring elements 13, 14 hence form hooks which provide for an anchoring of the implantable medical device 1 on tissue, in that the anchoring elements 13, 14 extend through the tissue and, by forming hooks, fix the implantable medical device 1 to the tissue.

In the embodiment of Fig. 3, the anchoring elements 13, 14 extend into different depths of the tissue. In particular, the apices 132, 142 of the anchoring elements 13, 14 are arranged at different heights HI, H2 with respect to the body 150, such that the apices 132, 142 come to lie at different depths within the septum M. As visible from Fig. 3, each anchoring element 13, 14, in the embodiment of Fig. 3, comprises an electrode 131, 141 which is placed at the apex 132, 142 of the respective anchoring element 13, 14. As the apices 132, 142 are arranged at different heights HI, H2 with respect to the body 150 and hence, in an implanted state of the implantable medical device 1, come to lie at different depths within tissue, by means of the different electrodes 132, 142 an excitation at different locations within the tissue may be provided, in particular within the septum M of the heart.

This may be used, as indicated in Fig. 3, in particular to provide for a pacing at the left bundle branch LBB. In particular, one of the electrodes 131, 141 may be located in the vicinity of the left bundle branch LBB, such that the respective electrode 131 of the anchoring element 13 may couple with the left bundle branch LBB and hence may capture the left bundle branch LBB to inject signals into the left bundle branch LBB and/or receive sense signals from the left bundle branch LBB.

The implantable medical device 1 may comprise more than two anchoring elements 13, 14, for example three, four, five, six or even more anchoring elements 13, 14, for example in the shape of tines. Each anchoring element 13, 14 herein may comprise one or multiple electrodes 131, 141 being placed at different heights HI, H2 with respect to the body 150.

This is further illustrated in another example in Fig. 4. In the example of Fig. 4 anchoring elements 13, 14 each comprise multiple electrodes 131A-131C, 141A-141C, the electrodes 131A-131C, 141A-141C being placed at different heights H1-H6 with respect to the body 150, as indicated in Fig. 4.

As different electrodes 131, 131A-131C, 141, 141A-141C, in the embodiments of Figs. 3 and 4, may be placed at different depths within tissue and hence may provide for an excitation and/or sensing at different depths within tissue, one or multiple electrodes 131, 131 A- 131 C, 141, 141A-141C may be selected during operation of the implantable medical device 1 in order to provide for a pacing and/or sensing action. In particular, algorithms for operating the implantable medical device 1 may include a configuration algorithm by which one or multiple electrodes 131, 131 A- 131 C, 141, 141A-141C are selected which may provide for an optimum coupling to the left bundle branch LBB, such that an effective stimulation and/or sensing at the left bundle branch LBB may be achieved.

Because electrodes 131, 131 A- 131 C, 141, 141A-141C may be selected after implantation for achieving an effective operation of the implantable medical device 1, implantation may become easy. In particular, it is not required to place a particular electrode 131, 131A- 131C, 141, 141A-141C at a particular location and depth within the tissue in order to for example reach the left bundle branch LBB. The implantable medical device 1 may generally be placed on the tissue in the vicinity of the left bundle branch LBB, wherein subsequently - after implantation - a subset of the electrodes 131, 131A-131C, 141, 141 A- 141C may be selected for emitting and/or sensing electrical signals.

Referring now to Fig. 5, each anchoring element 13, 14 may have the shape of a flexibly bendable tine, wherein the tine may for example comprise an electrically conductive core 134, 144 formed for example from a nickel titanium alloy material, such as nitinol. The core 134, 144 herein may be covered, substantially along its entire length, by a coating

135, 145 which is electrically insulating. The coating 135, 145 herein exposes the core 134, 144 for example at one location towards the outside to form an electrode 131, 141 for example in the region of the apex 132, 142 of the anchoring element 13, 14. The electrode 131, 141 may come into electrical contact with surrounding tissue, such that a coupling to the tissue may be achieved.

If multiple electrodes 131, 131 A- 131 C, 141, 141A-141C shall be formed on an anchoring element 13, 14, this may be achieved by exposing the core 134, 144 at multiple locations to the outside by removing the coating 135, 145.

In another embodiment, in order to provide electrodes 131, 131A-131C, 141, 141A-141C which are electrically independent of each other, each tine may have a multilayered configuration, wherein each electrode 131, 131A-131C, 141, 141A-141C is associated with a particular, electrically conductive layer, which is electrically separated from another electrically conductive layer by an intermediate, insulating layer. In yet another embodiment, an anchoring element 13, 14 may be formed as a tine from a plastics material, wherein one or multiple electrodes may be placed on the body of the tine and may be electrically coupled for example by means of electrical conductors being embedded in the plastics body.

In yet another embodiment, the anchoring elements 13, 14 may for example be formed from flexible circuit boards, formed for example from a liquid crystal polymer material (LCP). In order to provide for a mechanical stabilization, herein, one or multiple metallic wires, such as nitinol wires, may be embedded in the circuit boards.

The idea of the invention is not limited to the embodiments described above.

The implantable medical device may have the shape of a stimulation device comprising leads, or may have the shape of a leadless pacemaker device.

Anchoring elements may have the shape of tines, wherein at least two anchoring elements may be provided. Each anchoring element herein may carry one or multiple electrodes, such that an electrical coupling to surrounding tissue may be established by a set of electrodes of one or multiple anchoring elements.

LIST OF REFERENCE NUMERALS

1 Implantable medical device

10 Lead 100 Lead body

101 Distal end 11 Lead 12 Generator

13 Anchoring element (tine) 130 End

131, 131A-C Electrode

132 Apex

133 End

134 Core 135 Coating

14 Anchoring element (tine) 140 End

141, 141A-C Electrode 142 Apex 143 End

144 Core

145 Coating

15 Leadless device 150 Body (housing) 151 Distal end

16 Processing device

AVN Atrioventricular node

H HIS bundle

H1-H6 Height 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