An implantable direct-current electrode assembly (20) has two implantable electrodes (30, 40) and a control unit (50), to which the first (30) and the second (40) electrodes are electrically connected, wherein the control unit is configured to establish a potential difference between the two electrodes, so that a direct current can flow (55) between the two electrodes. The first electrode (30) is a coil electrode configured to be provided in the right half (12) of the heart (10) having a maximum length that is predetermined by the distance between the entry of the right atrium (14) and the tricuspid valve. The counter-electrode is from the group encompassing a coil electrode (40) configured to be positioned in the coronary sinus at the height of the left atrium (24) or an heart-external coil electrode configured to be attached to the exterior wall (25) of the left atrium.

TECHNICAL FIELD

The present invention relates to an implantable direct-current electrode assembly with two implantable electrodes and a control unit, to which the first and the second electrodes are electrically connected through leads. The control unit is designed to establish a potential difference between the two electrodes, so that a direct current can flow between the two electrodes.

PRIOR ART

Similar electrode assemblies are known from WO 2017/021255, wherein the first coil electrode is positioned between the tricuspid valve and the apex of the right ventricle lying opposite the tricuspid valve and the pulmonary valve touching the right ventricular wall. A second electrode is positioned on the epicardial site of the left ventricular wall (touching the left ventricular wall externally) or such a second electrode is positioned inside the coronary sinus pushed downwards to the left ventricle apex of the left ventricle. Then a direct-current flow is initiated between the coil electrode in the right ventricle and the coil electrode in the coronary sinus (sinus coronarius) which leads to an electric current flow through the left ventricle wall across the septum. It is furthermore known from WO 2006/106132 or WO 2017/021255 that a damaged heart muscle can be treated for prolonged time periods through application of a direct-current which strength is far below the threshold which is sufficient to induce a contraction of the heart. The current was defined as a direct-current that could not excite the cardiomyocytes or introduce a contraction of the heart.

SUMMARY OF THE INVENTION

Based on this prior art it is an object of the present invention to prevent or treat already existing atrial fibrillation.

This object is achieved for an implantable direct-current electrode assembly providing the first electrode as a coil electrode configured to be provided in the right half of the heart having a maximum length that is mainly predetermined by the distance between the entry of the electrode into a venous vessel and the right atrium and the tricuspid valve. The second electrode is the counter-electrode and can either be a coil electrode configured to be positioned in the vessel of the coronary sinus at the height of the left atrium or the second electrode is a heart-external coil or patch electrode configured to be attached to the exterior wall of the left atrium.

It has been found by the inventors, that providing an electrode assembly with a shorter first electrode to be placed inside the right atrium attached to the atrium wall and a second electrode in the coronary sinus with a shorter introduction portion into the sinus, while providing a direct-current flow between the two atrium portions suppresses the initiation of atrial fibrillation or diminish or eliminate an already existing atrial fibrillation. The shorter introduction portion makes the second conducting electrode part to be positioned horizontally just above the valve of the left atrium.

According to another embodiment it is also possible to provide the second electrode on the outside of the heart and to attach it along the outer atrium wall at the epicardial site of the left atrium. This can be done through stitching the alongside positioned electrode on the wall or the electrode comprises side spikes, entering into the atrium wall. This can be a coil electrode or a patch electrode stitched to the atrium wall or at the pericardium encompassing the atrium.

When the coil electrode is configured to be positioned in the coronary sinus at the height of the left atrium, then it preferably comprises an isolated anchoring portion extending beyond the electrode portion ending in a tip having a predetermined length. Said predetermined length of the isolated anchoring portion allows the electrode to follow the bend of the vena cardiaca magna into the direction of the left ventricle. Preferably, the isolated anchoring portion comprises pre-bent curved structure to be positioned against a plurality of contact points inside the cross-section of the tapering vena cardiaca magna until the tip of the isolated anchoring portion. In a simpler embodiment, the cross-section of the tapering vena is filled by the tip of the isolated anchoring portion as shown inFIG. 1, but the version of the tip portionFIG. 6is preferred by far. The isolating portion can have the same diameter as the core around which the helix-shaped electrode is wound. It can have a constant diameter until the rounded tip for a specific predetermined fixation point, maintaining the electrode portion in the region before the bend of the vena.

The electric connection between the electrically connected first and second electrodes and the control unit can be single wired isolated lines.

The first or second electrode can comprise solely one or more spirals wound around an isolating core being in one piece with the isolating cladding of the electric connection with no or one or more attachment spikes, but comprising the naked anchoring portion attached in one piece.

On the other side attachments spikes can be are provided at the first electrode comprising one or more free ends. There can also be provided three or four free ends spanning a triangle or square, respectively, in a plane perpendicular to the longitudinal direction of the electrode in front of the electrode end.

There can be provided two or three groups of one or two free ends extending essentially transverse to the longitudinal direction of the electrode, each group provided between a transition portion at the beginning of the electrode and the tip of the electrode, preferably at the beginning, the tip and in the case of three groups in the middle between the beginning and the end of the electrode. Each said group can comprise two free ends having an angle between 45 and 90 degrees in a plane perpendicular to the longitudinal direction of the electrode in front of the electrode end.

These free end(s) can be tapering each into an anchoring spike or into an anchoring hook.

The coil electrode configured as a heart-external coil electrode to be attached to the exterior wall of the left atrium can also be a patch electrode.

Further embodiments of the invention are laid down in the dependent claims.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1shows a perspective schematic view of a heart10and an electrode assembly20according to a first embodiment of the invention.

The implantable electrode assembly20comprises two leads having two implantable electrodes30and40, as well as an electronic control unit50, usually provided in a case, provided in a distance from the heart10, wherein also a battery is placed in the case to provide the necessary power supply.

The two electrodes30and40are connected via two single wire connections51and52with said electronic control unit50. The two single wire connections51and52forming the flexible leads as well as the control unit case50are electrically isolated against the environment. The control unit50is configured to create a potential difference between the two electrodes30and40extending beyond the two isolated single wire connections51and52, which potential difference allowing a direct-current to flow between the two electrodes30and40along arrow55.

The first electrode30is a right atrium electrode, configured to be positioned in the right atrium and is a coil electrode. The length of the coil atrial electrode30, i.e. the non-isolated part of the lead reaching from the electronic control unit50to the transition portion35, is predetermined through the distance between the entry of the right atrium14and the tricuspid valve16, especially chosen between 6 and 8 cm and is provided with an anchoring tip37(not represented inFIG. 1but shown inFIG. 3) to be positioned preferably within the right atrium touching the atrial wall15from the inside. There are other attachment possibilities as noted in connection with the second electrode (in the embodiment according to electrode140). The total length of the lead plus electrode can be between 50 and 80 cm.

The second electrode40is a coronary sinus electrode, configured to be positioned in the coronary sinus18and is also a coil electrode. The coronary sinus coil electrode40comprises a smaller diameter than the coil atrial electrode30since it has to enter the coronary sinus18and has to push forward into the vena cardiac magna until the vena cardiac magna bends into the direction of the left ventricle. The coil electrode40is attached at a shorter isolated introduction portion41so that it is not pushed into the tapered end portion of the coronary sinus, but is positioned at the height of the left atrium24near the left atrium wall25. The coil electrode40further comprises a prolongation as an isolating anchoring portion42as shown in connection with the embodiment ofFIG. 6. The length of the anchoring portion42can be between 3 and 6 times the length of the electrode portion40. In other words, the lead element comprises an isolated wire portion52with an introduction portion41, wherein the electrode portion40follows, wherein a further isolation core part42is provided extending beyond the electrode portion40until the tip33, wherein the length of this isolation core part42is predetermined to allow to be lodged from the point in the vena cardiaca magna where the vena cardiaca magna bends into the direction of the left ventricle.FIG. 1shows a more or less straight end portion of the isolation core part42. It is, however, preferred that the isolation core part42does not fill the volume of the lumen of the size reducing vena cardiaca magna but that the portion until the tip32is bent in several preformed waves to push against opposite side of the lumen of the vena cardiaca magna to position the second electrode40at a predetermined place and securely lodged there.

When a potential difference is applied between the two electrodes30and40by means of the electronic control unit50, since the wires51and52are isolated against the environment, a direct-current is flowing according to arrow55through the heart muscle in the biatrial area, i.e. across from the left atrium14to the right atrium24through the atrial septum117. Depending on the preferred direction of the current flow, the electrode30can be set as a cathode or anode with the electrode40as matched counter electrode accordingly.

The electronic control unit50is preferably programmable to predetermine a time interval within which the potential difference is maintained to obtain the direct-current flow, which can range from some minutes, over an interval of 30 minutes or an hour until a number of hours, days or months, wherein the electrode30is the cathode to define the current flow. After a predefined time, the current direction can be inverted, wherein the electrode40becomes the cathode and a similar time interval is provided after such a first time interval. This changes the direction of current flow according to arrow55. This sequence of change of current flow inversion can be continued for prolongated periods of time, e.g. for up to several months or even years.

It is also possible to change the current strength while inverting the current flow, since the impedance between the two electrodes30and40can be dependent on the direction55of the current flow. The amount of the direct current flow is predetermined to be far below the stimulation threshold, especially chosen to have a current density of 0.1 microampère/cm2to 1 milliampère/cm2. The electronic control unit50can comprise a control to maintain the current density below a maximum threshold. Inverting a current flow has to be executed quasi-stationary, i.e. decreasing the current density over several minutes to zero and raising it with the opposite leading sign to the predetermined new direct current density level to avoid any rhythm disturbances which can potentially lead to dys- or arrhythmia.

FIG. 2shows a perspective schematic view of a heart10and an electrode assembly120according to a second embodiment of the invention. According to this embodiment, a first electrode30is provided in the same way as in the first embodiment in the wall15of the right atrium14. The second electrode140is attached at the outer wall25of the left atrium15. This can be done through stitching of the electrode140, positioned just in parallel and along on the left atrium wall25(stitching not actually shown inFIG. 2) or the electrode140can comprise two or more lateral spikes147, as shown inFIG. 5, which are entering the left atrium wall25. An additional planar attachment as covering the electrode via a patch is possible as well. Such a patch can be a mesh or a thin electro-conductive film covered on the backside with silicone.

It is also possible to use a patch electrode at the place of a coil electrode140. Then a patch electrode as disclosed in WO 2016/016438 or in WO 2006/10132 can be used with the proviso that it is attached, especially stitched at the epicardium of the left atrium or at the pericardium covering the left atrium. Such a patch electrode has the advantage of a larger surface reducing the current density crossing the heart portions and at the same time allowing to cover a larger portion of the surface atrial septum117, when the direct current flow according to arrow55extends between the smaller rectangle (in a cross-section approach) of the coil electrode30and the entire surface of a patch attached near the left atrial external wall.

FIG. 2has less reference numerals thanFIG. 1, so that additional references are introduced here, which also applies toFIG. 1. The heart10is shown with the right ventricle13and the left ventricle23, separated by the septum17. The right atrium14is separated by valve16from the right ventricle13. The outer wall of the right atrium14is right atrium wall15. On the other side, the left atrium24has the left atrium wall25within which is located portions of the coronary sinus18within which is provided the second electrode40of the first embodiment.

FIG. 3shows the distal end of a coil electrode30for the first electrode according to an embodiment of the invention, i.e. to be applied for an embodiment of the assembly according toFIG. 1orFIG. 2. The electrode is far simpler constructed than usual coil electrodes for pacemakers etc. The single-wire51comprises an electrically conductive core58and an isolating cladding59. The cladding59ends in an area in front of the electrode30comprising the helix shaped distal end having the electrically conductive coil31around the electrode core33. The transition portion35comprises the spot where the single wire electrically conductive core exits the cladding59which continues as electrode core33. The diameter of the core33is less than the diameter of the cladding59as well as that the helix shaped electrically conductive coil31has a smaller diameter than the cladding59or has at the most its diameter.

The coil electrode30ofFIG. 3comprises a tip36with three free ends37building an anchoring tip, especially a tip spanning a triangle at the three tips. There are two principle methods of fixation of the electrode to differentiate. One is a traumatic one the other one an atraumatic fixation. Various available anchoring facilities for the electrodes consists of flanges, books, prongs, jaws and various types of screw and spiral tips. Preferably, the ends are provided in a same plane which is perpendicular to the longitudinal axis of the electrode tip. The anchoring tip is connected with the core33and then with the cladding59and are made of the same isolating material. This allows to anchor the electrode tip36at the right atrium wall15from the inside without providing any or only little current or potential to the atrium wall15. The direct current is traversing the upper portion of the septum at the level between the right atrium14and the left atrium24. If there is a small direct current flowing through the right atrium wall15this could prevent atrial fibrillation starting from the right atrium as such.

FIG. 4shows a coil electrode240to be attached at the outside of the atrium wall as exterior electrode140as shown in the embodiment ofFIG. 2or to be placed in the coronary sinus18according to the embodiment ofFIG. 1(however, with tip32directly ending in front of the electrode portion40). Similar features have received the same or similar reference numerals throughout the description. The non-conducting portion of the electrode40is similar to the electrode30. One difference is inter alia that the helix shaped conductive part31is closer packed than inFIG. 3. However, it is also possible to use the closer packed part31inFIG. 3and the lesser packed conductive portion ofFIG. 3in the embodiment ofFIG. 4. The closed packed portion31provides a full conductive surface in front of the septum17. The main difference between the two electrodes is the blunt end32allowing to push the electrode40into the coronary sinus18, wherein also here the electric conductive part has a smaller or at most similar diameter than the cladding59of the isolated part of the introduction portion41. The electrode40is positioned in the coronary sinus18preferably in a way that the electrode is similar to parallel to the heart valves or parallel to the first electrode30or in between these two positions.

It is also possible to use this electrode40as second electrode in the embodiment ofFIG. 2. Then the electrode is stitched at the outer surface of the left atrium wall25and can additionally be covered by a patch also attached to the atrium wall25, especially with single stitches or sutures. Use of glue is possible but reduces the conductivity towards the electrode.

FIG. 5shows a further embodiment for the outer atrium electrode140. The main difference between the embodiment ofFIG. 4and the embodiment ofFIG. 5lies in the side spikes147.

There are provided three or twice time three in an angle of between 45 and 90 degrees on one side of the tip portion seen in a cross section view. The spikes147are provided at the transition portion35, at the rounded tip32as well as in the middle between these two length positions.

FIG. 6shows a further embodiment for the second inner atrial electrode40as used in connection with the embodiment of the assembly according toFIG. 1. The second electrode40is a coronary sinus electrode, configured to be positioned in the coronary sinus18. The initial introduction portion52as well as the electrode portion40beyond the transition portion35is shown as positioned in the coronary sinus18and in the vena cardiac magna until the vena cardiac magna bends into the direction of the left ventricle. Beyond the coil electrode40is attached an isolated anchoring portion42which follows the bending of the vena cardiac magna and is pushed into the tapered end portion of the coronary sinus.

Since the isolated anchoring portion42is usually several times (3 to 6 times) longer than the electrode portion41, the end until the tip32is shown separately inFIG. 6. It is preferred that the diameter of the end of the isolated anchoring portion42is e.g. smaller and comprises a number of preformed bends in several preformed waves to push against opposite side of the lumen of the vena cardiaca magna to position the second electrode40at a predetermined place and securely lodged there. Then the isolated anchoring portion42is not inferring with the blood flow in the vessel.

The length of this isolation core part42is predetermined to allow to be lodged from the point in the vena cardiac magna where the vena cardiac magna bends into the direction of the left ventricle. Preferably, when advancing the electrode30, a mandarin is lodged in a hollow preformed tip portion43to straighten the preformed tip portion43. When this preformed tip portion43is in position beyond the bent, then the mandarin is retracted and the (e.g. memory form) metal bends again into its original shape, preferable providing a plurality of contact points44against opposite walls of the vena cardiaca magna. It is also possible that the preform bends back into a helix-shaped form positioned like a stent in the vessel; then the preformed tip portion43does not have distinct contact points but is pushed in a helix shape from the inside against the vessel walls.

Thus, the second electrode40is also positioned at a predetermined place and securely lodged there with contact points44. The diameter of the isolation core part42can therefore be constant and just end in a rounded tip32.FIG. 6shows that it is a flexible part42, wherein the isolated anchoring portion43comprises pre-bent curved structure to be positioned against a plurality of contact points44inside the cross-section of the tapering vena cardiaca magna until the tip32of the isolated anchoring portion42. Other e.g. memory metal applications are possible to provide a good anchoring in the vena cardiaca magna.

The present invention allows a biatrial monophasic electrical sub-stimulation. The direct-current flow remains largely below-sub-threshold levels, i.e. without activating the physiologic conduction system. The first electrode30is positioned in the right atrial appendage14and the other electrode40or140is positioned over the left atrium24either at the left posterior atrial wall15or within a coronary sinus. In the letter case, the introduction of the electrodes30and40into the patients could be accomplished by intravenous access, otherwise a transthoracic assess would be necessary. The longstanding provision of sub-threshold direct-current reverses the pathological structural remodelling of atria14and24in patients with persistent atrial fibrillation or tachyarrhythmias.

The electric current enhances the proliferation of cardiomyocytes and modulates the expression of metalloproteinases and their inhibitors. Furthermore, the direct-current stimulation modulates the expression of pro-inflammatory cytokines.