LEADLESS PACEMAKER AND METHODS FOR ELECTRICALLY STIMULATING CARDIAC TISSUE, SENSING ELECTRICAL SIGNALS AND COMMUNICATING BETWEEN A LEADLESS PACEMAKER AND AN EXTERNAL DEVICE

Abstract

A leadless pacemaker includes at least one fixation element for fixing the leadless pacemaker to cardiac tissue, a communication unit electrically connected to the fixation element, so that the fixation element is configured to act as a communication antenna for transmitting signals generated by the communication unit to an external device and/or receiving signals from an external device, and a therapy unit for generating electrical signals to electrically stimulate cardiac tissue. The fixation element is configured to act as an electrode for electrically stimulating cardiac tissue and/or sensing electrical signals of the cardiac tissue. A method for electrically stimulating cardiac tissue, a method for sensing electrical signals of cardiac tissue by using the leadless pacemaker, and a method for communicating between a leadless pacemaker and an external device are also provided.

Claims

1. A leadless pacemaker, comprising: at least one fixation element for fixing the leadless pacemaker to cardiac tissue; a communication unit electrically connected to said at least one fixation element, causing said at least one fixation element to act as a communication antenna for at least one of transmitting signals generated by said communication unit to an external device or receiving signals from an external device; said at least one fixation element configured to act as an electrode for at least one of electrically stimulating cardiac tissue or sensing electrical signals of the cardiac tissue; and a therapy unit for generating electrical signals to electrically stimulate cardiac tissue.

2. The leadless pacemaker according to claim 1, wherein said at least one fixation element is electrically connected to said therapy unit, permitting a voltage to be applied to said at least one fixation element.

3. The leadless pacemaker according to claim 2, which further comprises a signal splitter for separating signals of said communication unit from signals of said therapy unit, said at least one fixation element being electrically connected to said communication unit and to said therapy unit by said signal splitter.

4. The leadless pacemaker according to claim 1, which further comprises a pacing electrode electrically connected to said therapy unit, said at least one fixation element configured to act as a counter electrode, permitting a voltage to be applied between said pacing electrode and said at least one fixation element.

5. The leadless pacemaker according to claim 4, which further comprises a ring electrode and an electronic circuit, said electronic circuit configured to determine a far field signal of the cardiac tissue from a first electrical signal sensed between said pacing electrode and said at least one fixation element and a second electrical signal sensed between said pacing electrode and said ring electrode.

6. The leadless pacemaker according to claim 5, which further comprises a distal end and a proximal end of the leadless pacemaker, said pacing electrode positioned at said distal end and said ring electrode positioned at said proximal end.

7. The leadless pacemaker according to claim 1, wherein said at least one fixation element is shaped as a helical screw.

8. The leadless pacemaker according to claim 1, wherein said at least one fixation element includes at least one hook for fixing the leadless pacemaker to the cardiac tissue.

9. The leadless pacemaker according to claim 1, wherein said communication unit is directly connected to said therapy unit for exchanging information between said communication unit and said therapy unit.

10. The leadless pacemaker according to claim 1, which further comprises an integration unit, said communication unit being connected to said therapy unit by said integration unit for exchanging information between said communication unit and said therapy unit.

11. The leadless pacemaker according to claim 1, which further comprises a power supply connected to said communication unit and to said therapy unit for providing electrical energy to said communication unit and to said therapy unit from said power supply.

12. The leadless pacemaker according to claim 1, wherein said at least one fixation element includes or is formed of an electrically conductive material.

13. The leadless pacemaker according to claim 12, wherein said electrically conductive material is Nitinol.

14. A method for electrically stimulating cardiac tissue by using a leadless pacemaker, the method comprising: providing a leadless pacemaker according to claim 1; using said at least one fixation element to electrically stimulate the cardiac tissue; and using said at least one fixation element as an electrode.

15. A method for sensing electrical signals of cardiac tissue by using a leadless pacemaker, the method comprising: providing a leadless pacemaker according to claim 1; using said at least one fixation element to sense electrical signals of the cardiac tissue; and using said at least one fixation element as an electrode.

16. The method according to claim 15, which further comprises: providing the leadless pacemaker with a pacing electrode, a ring electrode and an electronic circuit; sensing a first electrical signal between said pacing electrode and said at least one fixation element; sensing a second electrical signal between said pacing electrode and said ring electrode; and using the electronic circuit to determine a far field signal of the cardiac tissue.

17. The method according to claim 16, wherein the far field signal of the cardiac tissue is an atrial signal.

18. A method for communicating between a leadless pacemaker and an external device, the method comprising: providing a leadless pacemaker according to claim 1; using said at least one fixation element as a communication antenna to at least one of: transmit signals generated by said communication unit to the external device, or transmit signals received from the external device to said communication unit.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0054] FIG. 1 is a diagrammatic, longitudinal-sectional view of a first embodiment of the leadless pacemaker including hook-shaped fixation elements;

[0055] FIG. 2 is a longitudinal-sectional view of a second embodiment of the leadless pacemaker including hook-shaped fixation elements and an additional proximal ring electrode; and

[0056] FIG. 3 is a longitudinal-sectional view of a third embodiment of the leadless pacemaker including a fixation element shaped as a helical screw.

DETAILED DESCRIPTION OF THE INVENTION

[0057] Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a diagrammatic, sectional view of a leadless pacemaker 1 for implantation into human or animal cardiac tissue according to a first embodiment. The leadless pacemaker 1 extends along a longitudinal axis L from a distal end D where the leadless pacemaker 1 is to be implanted into cardiac tissue to a proximal end P. A housing 15, particularly from a metallic material, encases the internal components of the leadless pacemaker 1. At the proximal end P, an implant/explant port 11 is positioned.

[0058] The leadless pacemaker 1 may be installed for example in a ventricle or an atrium of the heart, particularly into an inner wall of the ventricle or atrium.

[0059] In order to fixate or anchor the leadless pacemaker 1 in the cardiac tissue at its desired position, the leadless pacemaker 1 includes hook-shaped fixation elements 2 disposed at the distal end D. In the sectional view of FIG. 1, two fixation elements 2 are depicted, but the leadless pacemaker 1 may contain more than two fixation elements 2.

[0060] In order to provide electrical energy, the leadless pacemaker 1 includes a power supply 10 positioned in a power supply compartment 17 within the housing 15 adjacent the proximal end P of the leadless pacemaker 1. In particular, the power supply 10 may be a battery. Instead of or in addition to a battery, the leadless pacemaker may contain an energy harvesting unit as a power source 10 or as part of the power source 10. Such an energy harvesting unit accumulates electrical energy, particularly by converting mechanical energy from motions occurring during beating of the heart to electrical energy.

[0061] The leadless pacemaker 1 further includes an electronic compartment 13, adjacent the power supply compartment 17, wherein the electronic compartment 13 is separated from the power supply compartment 17 by an inner wall 18a. In particular, the electronic compartment 13 is hermetically sealed from the adjacent compartments in particular to avoid fluid from entering the compartment and damaging the electronics.

[0062] Adjacent the electronic compartment 13, an electrode compartment 19 is positioned within the housing 15 at the distal end D of the leadless pacemaker 1. The electrode compartment 19 is separated from the electronic compartment 13 by an inner wall 18b.

[0063] An electronic module 14, particularly for controlling pacing (electric pulse generation) and sensing of electrical signals of the heart, among other functions, is situated within the electronic compartment 13. The electronic module 14 is electrically connected to the power source 10 by an electric connection 12, which protrudes through a feedthrough of the inner wall 18a separating the electronic compartment 13 from the power supply compartment 17.

[0064] The electronic module 14 includes a communication unit 3 for communicating with an external device and a therapy unit 4 for generating electrical signals to electrically stimulate cardiac tissue in which the leadless pacemaker 1 is implanted. Both the communication unit 3 and the therapy unit 4 are electrically connected to the power supply 10 by the electric connection 12 and thereby energized by the power supply 10.

[0065] In the example depicted in FIG. 1, the communication unit 3 and the therapy unit 4 are connected by using an integration unit 9 allowing communication between the communication unit 3 and the therapy unit 4.

[0066] The communication unit 3, which may be e.g. a transceiver, is electrically connected to the hook-shaped fixation elements 2 via electric connections 12 and an electrically conductive ring 20 to which the fixation elements 2 are mechanically connected. The ring 20 and a part of the hook-shaped fixation elements 2 are positioned within the electrode compartment 19 of the leadless pacemaker 1. The hook-shaped fixation elements 2 protrude through the housing 15 of the leadless pacemaker 1 to the exterior, where they are able to engage cardiac tissue when the leadless pacemaker 1 is implanted.

[0067] Due to their electrically conductive material and their connection with the communication unit 3, the hook-shaped fixation elements 2 serve as a communication antenna which is able to generate electromagnetic waves to transmit signals generated by the communication unit 3 to an external device, for example at frequencies within the MICS band (405 MHz) or the Bluetooth frequency of 2.4 GHz. Furthermore, the fixation elements 2 are also configured to receive signals from an external device, in such a way that they can be decoded and evaluated by the communication unit 3. This allows efficient wireless communication of the leadless pacemaker 1 with external devices.

[0068] The therapy unit 4 is electrically connected to a single pacing electrode 6, in such a way that a positive or negative electrical potential can be applied to the pacing electrode 6 for electric stimulation of the cardiac tissue. The pacing electrode 6 shown in FIG. 1 is a tip electrode having a ball-shaped tip 21 with a convex surface to increase the electric field generated at the pacing electrode 6. The electrode compartment 19 harbors a part of the pacing electrode 6, and the pacing electrode 6 protrudes the housing 15 of the leadless pacemaker 1 via a feedthrough. The tip 21 of the pacing electrode 6 is positioned exterior to the leadless pacemaker and protrudes from the housing 15 of the device, such that the tip 21 is in direct contact with the cardiac tissue into which the leadless pacemaker 1 is implanted, and such that the pacing electrode 6 can electrically stimulate the cardiac tissue when an electric potential is applied to the pacing electrode 6.

[0069] In the embodiment shown in FIG. 1, the hook-shaped fixation elements 2, which are at ground potential, serve as a counter electrode for the pacing electrode 6 in addition to their function of fixating the leadless pacemaker 1 in the cardiac tissue and their function as a communication antenna to communicate wirelessly with external devices. Using the fixation elements 2 as a counter-electrode for the pacing electrode 6 advantageously improves the local resolution of the electrical stimulation of the heart.

[0070] FIG. 2 illustrates an alternative embodiment of the leadless pacemaker 1 according to the invention. The pacemaker 1 is identical to the one depicted in FIG. 1 (see description above) except for the following additional features or alternative features.

[0071] In addition to the pacing electrode 6 and the hook-shaped fixation elements 2 serving as a counter electrode for the pacing electrode, the leadless pacemaker includes a ring electrode 7 near the proximal end P of the leadless pacemaker 1. In the sectional view shown in FIG. 2, two segments of the ring electrode 7 are shown, but the ring electrode 7 extends circumferentially around the periphery of the housing 15. The ring electrode 7 serves as an additional counter electrode for the pacing electrode 6 and has a specialized function in signal sensing as described below.

[0072] The electronic module 14 of the leadless pacemaker 1 according to FIG. 2 includes an additional electronic circuit 8, which is connected to the pacing electrode 6, the fixation elements 2 and the ring electrode 7. The electronic circuit 8 is configured to analyze a first electrical signal sensed between the pacing electrode 6 and the fixation element 2 and a second electrical signal sensed between the pacing electrode 6 and the ring electrode 7 and to determine a far field signal, particularly generated in an atrium of the heart in the case of the leadless pacemaker being installed in the ventricle of the heart.

[0073] In contrast to setups known from the prior art, this allows a separation of far field signals generated distant from the implantation site of the pacemaker 1 from near field signals resulting from cardiac tissue near the implantation site.

[0074] Furthermore, in contrast to the embodiment shown in FIG. 1, the communication unit 3 of the pacemaker 1 according to FIG. 2 is directly connected to the therapy unit 4 by a data connection 16.

[0075] FIG. 3 shows a further embodiment of the leadless pacemaker 1 according to the present invention.

[0076] In contrast to the embodiments depicted in FIG. 1 and FIG. 2, the leadless pacemaker 1 according to FIG. 3 includes a single fixation element 2 shaped as a helical screw extending along the longitudinal axis L from the distal end D of the leadless pacemaker 1. The pacemaker 1 can be anchored in the cardiac tissue at its desired location by screwing the fixation element 2 into the cardiac tissue.

[0077] Similar to the previously discussed embodiments, the screw-shaped fixation element 2 is connected to the communication unit 3, in such a way that it may serve as a communication antenna to wirelessly transmit signals to and receive signals from an external device.

[0078] In addition, the screw-shaped fixation element 2 is electrically connected to the therapy unit 4, such that a positive or negative electric potential can be applied to the fixation element 2 relative to ground potential of the housing 15 or a separate ring electrode (not shown in FIG. 3, compare FIG. 2). In this manner, the fixation element 2 may be utilized as a pacing electrode, thereby eliminating the need for a designated pacing electrode 6 as shown in FIG. 1 and FIG. 2. This advantageously reduces weight and complexity of the leadless pacemaker 1.

[0079] In order to separate the signals from the communication unit 3 and the therapy unit 4, which are commonly characterized by separate frequencies, a signal splitter 5 is provided as part of the electronic module 14 of the leadless pacemaker 1 according to FIG. 3. The signal splitter 5 is electrically connected to both the communication unit 3 and the therapy unit 4, and electrically connected to the helical fixation element 2 via an electrical connection 12 and an electrically conductive ring 20 to which the fixation element 2 is mechanically connected. Alternatively, the signal splitter may also be positioned outside of the electronic module 14, even outside of the electronic compartment 13.

[0080] In the example shown in FIG. 3, the communication unit 3 is directly connected to the therapy unit 4 by a data connection 16. Of course, it is also possible to connect the communication unit 3 to the therapy unit 4 via an integration unit 9, such as depicted in FIG. 1.

[0081] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teaching. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention.

[0082] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0083] 1 Leadless pacemaker [0084] 2 Fixation element [0085] 3 Communication unit [0086] 4 Therapy unit [0087] 5 Signal splitter [0088] 6 Pacing electrode [0089] 7 Ring electrode [0090] 8 Electronic circuit [0091] 9 Integration unit [0092] 10 Power supply [0093] 11 Implant/explant port [0094] 12 Electric connection [0095] 13 Electronic compartment [0096] 14 Electronic module [0097] 15 Housing [0098] 16 Data connection [0099] 17 Power supply compartment [0100] 18a, 18b Inner wall [0101] 19 Electrode compartment [0102] 20 Ring [0103] 21 Tip [0104] D Distal end [0105] P Proximal end [0106] L Longitudinal axis