Intracardiac device and fixation method thereof
Patent Information
- Application Number
- JP2024514606
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2021-11-01
- Filing Date
- 2022-09-30
- Publication Date
- 2025-08-08
- Estimated Expiration
- 2042-09-30
AI Technical Summary
Existing intracardiac device fixation mechanisms are inadequate for thin-walled atrial tissue, requiring secure electrode contact and easy implantation without high manufacturing costs.
An intracardiac device with inwardly facing tines that pivot and flex outward upon contact with tissue, penetrating and grasping the atrial wall to ensure reliable mechanical and electrical contact, using a method that involves pressing the tines against the tissue, causing them to pivot outward and then relaxing to tighten the tissue against the electrode.
Provides secure and reliable fixation of intracardiac devices to thin-walled atrial tissue with improved mechanical and electrical contact, reducing manufacturing complexity and cost, and minimizing tissue injury risk.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present invention relates to implantable intracardiac devices, such as implantable intracardiac pacemakers. [Background technology]
[0002] Active or passive intracardiac devices, such as implantable intracardiac pacemakers (also known as leadless pacemakers), are well-known miniature medical devices that are implanted entirely in the patient's heart chambers or atria. Intracardiac pacemakers are used in patients with bradycardia, i.e., when the heart beats too slowly to meet the patient's physiological needs. Intracardiac devices apply electrical stimulation to the heart in the form of pulses to generate a physiologically appropriate heart rate (intracardiac pacemakers) and / or in the form of shocks for cardioversion or defibrillation to restore a more normal heart rhythm. Alternative or additional functions of intracardiac devices include providing other electrical or electromagnetic signals to the heart or its surrounding tissues, sensing electrical or electromagnetic signals, or other physiological parameters of the heart and / or its surrounding tissues.
[0003] Fixation mechanisms for intracardiac devices in the field are currently used only for ventricular implantation. As the use of intracardiac pacemakers expands to dual chamber applications, specialized atrial fixation methods will also be required. The atrial anatomy dictates safe and reliable fixation approaches. The right atrial lateral wall and appendage (a pocket off the main chamber) are very thin and sparsely covered with pectinate muscle. In contrast, the septal wall and right atrial posterior wall are smooth without pectinate muscle.
[0004] US Patent No. 5,399,633 discloses an intracardiac medical device for implantation in one atrium, comprising an electrode formed as a similar fixation mechanism with a pair of large diameter double helices with positive deflection near the base of the distal end of the device. To fixate, the double helices are screwed into the wall of the heart. The purpose of this shape is to facilitate implantation of the device, but it makes the device very difficult to unscrew, as it is firmly anchored to the wall. Furthermore, the distal end of the double helix may have a serrated edge that prevents the device from unscrewing from the heart chamber wall. Such fixation mechanisms appear to be inapplicable to the thin atrial wall. [Prior art documents] [Patent documents]
[0005] [Patent Document 1] U.S. Pat. No. 8,700,181 Summary of the Invention [Problem to be solved by the invention]
[0006] Thus, there is a need for an atrium implantable intracardiac device that provides reliable electrode contact with thin-walled atrial tissue matrix and has fixation mechanisms / methods that ensure easy implantation and low manufacturing labor and cost. [Means for solving the problem]
[0007] The above problem is solved by a method for anchoring an intracardiac device to an anchoring region in the tissue of a patient's heart according to claim 1 and an intracardiac device according to claim 4.
[0008] In particular, a method for anchoring an intracardiac device to an anchoring region within tissue of a patient's heart includes the steps of: the intracardiac device comprising an electrode and at least two tines attached to a distal end of the intracardiac device adjacent the electrode, each of the at least two tines having a distal end in the form of a hook with its farthest distal end section facing inwardly, pivotable and / or bendable outwardly about a bend point at its proximal end, and inwardly preloaded; moving the intracardiac device from the final state toward the fixation region until at least two tines contact tissue of the fixation region with at least two tines facing forward; Then, pressing the at least two tines against tissue at the fixation region such that the at least two tines pivot and / or bend outward, thereby penetrating the distal ends of the at least two tines into the tissue (intermediate state); Thereafter, pressure on the at least two tines against the tissue is removed, and then the at least two tines relax to a less constrained state (final state), thereby bunching or gripping a wall segment of the tissue by the at least two tines and pulling the wall segment towards the electrode.
[0009] More particularly, the intracardiac device comprises an electrode and at least two tines attached to a distal end of the intracardiac device adjacent the electrode, each of the at least two tines having a hook-shaped distal end with a distal-most section of the tine facing inwardly and being pivotable and / or bendable outwardly about a bend point at its proximal end, and the at least two tines are: when the at least two tines are pressed against tissue of the patient's heart at the fixation region, they pivot outwardly and / or bend outwardly, thereby causing distal ends of the at least two tines to penetrate the tissue; The intracardiac device is further adapted to bunch a wall segment of tissue and pull the wall segment towards the electrode when the intracardiac device is moved rearward a predetermined distance from the anchoring region.
[0010] In accordance with the present invention, the implantable intracardiac device comprises a plurality of inwardly pointing tines, i.e., hooks / curves that are naturally biased towards the longitudinal axis of the device. Upon contact with the anatomy (i.e., the surface of the cardiac tissue), physical interaction with the pre-curved tine shape forces the tines open against the preload, causing the individual tines to spread outward by bending and / or pivoting. Upon relaxation, i.e., removal of the applied force, the intracardiac device then moves backwards a predetermined distance from the anchoring region, and the hook-like tips of the spread tines grab the thin-walled tissue bundle and wrap the wall inward and in a direction towards the electrode.
[0011] The intracardiac device and fixation method provide reliable fixation with reliable mechanical and electrical contact between the electrode and the thin-walled atrial tissue matrix, as the tissue is brought closer to the electrode by gripping and bunching the matrix towards the electrode. Furthermore, the present invention allows for a reduction in the length of the tines required for device fixation, especially compared to the outward curvature of the tine shapes common to devices designed for intraventricular implantation currently available on the market. A further advantage is that in the fixed state of the proposed intracardiac device, there is little chance of the tips of the tines being exposed and pointing outward from the intracardiac device, compared to the tine-based anchors of currently available leadless pacing systems, which has potential benefits for subsequent device attachments that may mechanically or electrically engage the outwardly pointing tines, causing undesirable wear and / or reduced device performance. Rather, the distal ends of the tines penetrate the tissue reliably. Also, in the case of thin tissue matrix, the intracardiac device of the present invention and its respective fixation method form a positive means of forcing device contact with the tissue, compared to prevalent designs on the market, which may leave a "gap" between the electrode and tissue in thin tissue. Therefore, as an embodiment of an intracardiac device, it may be possible to consider supporting right atrial placement of a leadless pacemaker, however, the proposed design can also be used to anchor an intracardiac device in the right ventricle.
[0012] The implantable intracardiac device (e.g., a leadless pacemaker) may comprise a cylindrical housing having a longitudinal axis as described above and electrodes protruding from a distal end of the housing, the electrodes being pin-shaped and extending in the direction of the longitudinal axis. Furthermore, a header assembly may be disposed and attached to the distal end of the housing of the intracardiac device such that the electrodes protrude through the header assembly (i.e., through respective through openings or full openings of the header assembly). The openings may be central openings. The cylindrical housing comprises an electronic module, in particular having an integrated circuit including a processor, an energy source (e.g., a battery or coil (for wireless charging)), and, if applicable, a communication component such as an antenna. The integrated circuit may comprise a storage unit for data storage, or one or more built-in memory allocations for data storage. The processor may be adapted to process signals determined from the patient's body or signals received from the surrounding environment, and / or to generate signals for treatment of the patient's heart. Such signals may include electrical stimulation in the form of pulses to generate a physiologically appropriate heart rate, for example by providing anti-bradycardia or anti-tachycardia pacing, shocks for cardioversion or defibrillation to restore a more normal heart rhythm, and / or other electrical or electromagnetic signals to the heart or surrounding tissue. Such signals may be converted and transmitted by the electronic module and applied to the heart or surrounding tissue by pin-like electrodes. The pin-like electrodes are electrically connected to the electronic module and to an energy source. The hermetically sealed housing may include a biocompatible material, a portion of which may embody a conductive material (e.g., titanium) and may function as another electrode.
[0013] In one embodiment, the movement of the intracardiac device towards the fixation region is a pure longitudinal movement, and / or the movement of the intracardiac device back from the fixation region is a pure longitudinal movement or a combination of longitudinal and rotational movement (i.e., helical movement). Pure longitudinal movement is easily achieved during implantation, while the combined movement provides better fixation of the tines in the tissue of the heart. For example, the rotation can include a minimum of 10 degrees and / or a maximum of 45 degrees. As described above, relaxation of the tines results in longitudinal movement of the intracardiac device back from the fixation region (as a pure longitudinal movement or a combined movement). Such movement can have a length of about 3 mm or less.
[0014] In one embodiment of the fixation method, while compressing the at least two tines, the intracardiac device is moved towards the fixation region to press the tines against the tissue of the heart at the fixation region and to pivot and / or bend the tines outward against the inwardly directed preload (pretension). The pivoting and / or bending moves the distal end sections of the at least two tines such that the distal tips and at least a portion of the distal end sections of each of the at least two tines penetrate into the tissue of the heart at the fixation region. It is noted that the pivoting and / or bending increases the lateral distance D (distance D determined perpendicular to the longitudinal axis) of the distal sections of the opposing tines, such that the end sections of the different tines penetrate into tissue points further apart than the lateral distance of the end sections in the initial state (relaxed state) before pressing the tines against the tissue. As the tines move backward from the tissue after penetration, the outer distance D of the distal sections of the opposing tines decreases, so that the preload causes the tines to pivot back and bunch and inwardly wrap the tissue between the penetration points. This strengthens the mechanical and electrical contact between the electrode and the tissue. Thus, the outer distance D of the distal sections of the two opposing tines in the final state can be larger than in the initial state, where the distance D in the initial state is, for example, 2 mm to 5 mm, and the distance D in the final state is, for example, 7 mm to 12 mm.
[0015] In one embodiment, at the distal end of the intracardiac device, the electrode is positioned in a central location, preferably on the longitudinal axis of the intracardiac device, and the proximal ends of at least two tines are positioned peripherally around the electrode. In one embodiment, one tine of each pair of two tines is provided opposite the other tine of the pair. This provides a good distribution of forces within the tissue of the heart, especially when four or more tines are used as part of the fixation design.
[0016] In one embodiment, the length of the at least two tines (e.g., as shown in FIG. 2 with the symbol "LT") is in the range of 2 mm to 10 mm, and / or the exposed length of the electrode (the length that the electrode protrudes from the housing or header) is 5 mm or less, each length being determined from the distal end of the header in the direction of the longitudinal axis of the intracardiac device. The exposed length of the electrode is less than the length of the at least two tines.
[0017] Each tine has a distal end in the form of a hook (J-shaped) with at least one curved section bent inwardly, such that the furthest distal end (section) of the tine faces inward. The at least one curved section is located in the distal section of the tine. Each tine may be bendable in the region of the first curved section, i.e., the proximal section of the tine.
[0018] In one embodiment, the diameter of at least one bend in the distal end section of at least two of the tines is in the range of 1 mm to 3 mm.
[0019] In one embodiment, the distal end section / second curved portion of the at least two tines are curved such that their respective most distal ends (i.e., the distal tips of the tines) point towards the electrode. This embodiment has a lower risk of damage upon initial tissue contact (compared to tine-based leadless anchors available on the market today) since the most distal ends are initially protected. However, as compression of the at least two tines against tissue occurs and each tine pivots or bends, the most distal ends of the tines open, and this movement causes the most distal ends to increasingly point towards the tissue, i.e., extend at an angle relative to the longitudinal axis, providing a means for directly engaging the tissue.
[0020] In one embodiment, the distal sections of the at least two tines comprise one or more barbs. In one embodiment, the distal sections of the at least two tines comprise one barb disposed at the distal-most section of each tine. In one embodiment, the distal sections of the at least two tines comprise multiple barbs, one barb of the multiple barbs disposed at the distal-most section of each tine.
[0021] In one embodiment, the at least two tines comprise a proximal section and a distal section, the proximal section being straight and parallel to the longitudinal axis of the intracardiac device, and the distal section being formed as a hook. This embodiment is particularly advantageous when the catheter has a small profile. Furthermore, the straight proximal section ensures a direct approach of the tines to the tissue, which facilitates the tines spreading / bending outward when pressed against the tissue.
[0022] The invention will now be described in more detail with reference to the accompanying schematic drawings. [Brief description of the drawings]
[0023] [Figure 1] 1 shows a side view of a distal section of a first embodiment of an intracardiac device according to the invention at the beginning of a fixation method. [Diagram 2]2 shows an enlarged side view of the distal section of the intracardiac device shown in FIG. 1 in an initial state. [Diagram 3] 2 shows the distal section of the embodiment of FIG. 1 in an intermediate state. [Figure 4] 2 shows the distal section of the embodiment of FIG. 1 in a final state. [Diagram 5] 13 shows an enlarged view of a distal section of another embodiment of an intracardiac device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] 1 shows the distal end of a first embodiment of a method for anchoring an implantable intracardiac device (e.g., a leadless pacemaker) in an initial state prior to anchoring the device in a patient's cardiac tissue, the device being intended to be anchored to an atrial wall 10 of the patient's heart.
[0025] The intracardiac device includes a cylindrical housing 20. A header 22 and a tip electrode 24 are disposed at the distal end of the housing 20. The tip electrode 24 passes through the header 22 and protrudes from its distal end face. The length LE (see FIG. 2) of the electrode protruding from the distal end face of the header 22 in the direction of the longitudinal axis 26 is, for example, 5 mm or less.
[0026] The housing 20 of the intracardiac device contains the battery and the electronic module with the processor and ensures a hermetic seal of these components, which are electrically connected to the electrodes 24 and provide electrical stimulation of the heart or processing of electrical signals determined from the heart. Additionally, the housing 20 may contain components for communication, such as an antenna.
[0027] There are two or more tines 30 projecting from the distal end of the header 22. In preferred embodiments, three, four, five or more tines may be provided. The electrode 24 is centrally located on the longitudinal axis of the device. The tines 30 are disposed peripherally about the longitudinal axis, thereby surrounding the electrode 26.
[0028] Each tine 30 has a distal end 32 in the form of a hook with the furthest distal section of the tine facing inwards. In the initial state shown in Figure 1, the distal end 32 is formed such that the furthest end of its bend faces towards the electrode 24, meaning that this end section is not perpendicular to the longitudinal axis 26 but is inclined relative to this axis. The longitudinal length LT of the tines 30 is greater than the length LE of the electrode 24, the length LT being, for example, in the range of 2 mm to 10 mm.
[0029] The two tines 30 can be bent and / or pivoted outwardly against an inwardly directed preload such that each tine 30 pivots about a point at the proximal end of the tine 30 and / or bends at its proximal section (first curve), as shown in Figure 3. As the pivoting and / or bending occurs, the lateral distance D (see Figure 2) of the distal sections of the opposing tines 30 increases (see Figures 3 and 4).
[0030] Before the first step of the fixation method shown in FIG. 1, the intracardiac device has been minimally invasively implanted in the patient's heart, for example using a catheter. Here, the device is at a distance with respect to the fixation area of the atrial wall 10, for example (see FIG. 1). The device is moved towards the fixation area of the atrial wall 10 with at least two tines facing forward (see arrow P1 in FIG. 1) until at least two tines 30 contact the tissue of the fixation area. Then, the two or more tines 30 are pressed against the tissue at the fixation area (see arrow P2 in FIG. 3), so that the two tines 30 are bent and / or pivoted outward, whereby the distal ends of the at least two tines penetrate the tissue. This is because, due to the pivoting and / or bending, the most distal tip of each tine 30 does not point inwards, but points away from the electrode 24 towards the tissue (see FIG. 3). In a final step, the pressure on the tines 30 is removed, after which the tines 30 relax to a less constrained state, and at the same time, this relaxation of the tines 30 causes the intracardiac device to move backwards (e.g., 5 mm or less) from the fixation area (see arrow P3 in FIG. 4), thereby bunching or gripping the tissue wall segment 11 by the two tines 30 and pulling this wall segment 11 towards the electrode 24. This fixation method provides reliable mechanical and electrical contact.
[0031] The material of the tines 30 is, for example, Nitinol.
[0032] The tines 30 described above may be welded to the exterior surface of the intracardiac device housing 20 or to the header 22. Other attachment mechanisms may include clamping the base of the tines 30 within the header 22 or overmolding the base of the tines 30 within the header 22.
[0033] The above method is a reliable method for anchoring intracardiac devices within the atrial wall or other thin walls of the heart, which allows for ease of use and low manufacturing costs.
Claims
1. 1. A method for anchoring an intracardiac device to an anchoring region within cardiac tissue of a patient, the intracardiac device comprising an electrode (24) and at least two tines (30) attached to a distal end of the intracardiac device adjacent to the electrode (24), each of the at least two tines (30) having a distal end in the form of a hook with its farthest distal end section facing inward, pivotable and / or bendable outwardly about a bending point at its proximal end, and inwardly preloaded, the method comprising: With the at least two tines (30) facing forward, moving the intracardiac device towards the fixation region (arrow P1) until the at least two tines contact the tissue of the fixation region; Then, the at least two tines (30) are pressed against the tissue at the fixation region (arrow P2) so that the at least two tines (30) pivot and / or bend outward, thereby penetrating the tissue with the distal ends of the at least two tines; Thereafter, pressure on the tines (3) against the tissue is removed, thereby causing the at least two tines to bunch a wall segment (11) of the tissue and pull the wall segment (11) towards the electrode (24). A method comprising:
2. 2. The method of claim 1, wherein movement of the intracardiac device toward the fixation region is longitudinal movement and movement of the intracardiac device back from the fixation region is longitudinal movement or a combination of longitudinal and rotational movement.
3. The method according to claim 1 or 2, wherein the intracardiac device is moved towards the fixation region while pressing the at least two tines against the tissue at the fixation region (arrow P1).
4. and at least two tines (30) attached to a distal end of the intracardiac device adjacent to the electrode (24), each of the at least two tines (30) having a distal end in the form of a hook with the farthest distal end section of the tine facing inward and being pivotable and / or bendable outwardly about a bending point at its proximal end, the at least two tines (30) comprising: When the at least two tines (30) are pressed against the tissue of the patient's heart at the fixation region (arrow P2), they pivot and / or bend outward, thereby causing the distal ends of the at least two tines to penetrate the tissue; The intracardiac device is further adapted to bunch a wall segment (11) of the tissue and pull the wall segment (11) toward the electrode (24) when the intracardiac device is moved backward a predetermined distance from the fixation region (arrow P3).
5. 5. The intracardiac device of claim 4, wherein at the distal end of the intracardiac device, the electrode (24) is positioned in a central position and the proximal ends of the at least two tines (30) are positioned peripherally around the electrode (24).
6. The intracardiac device according to claim 4 or 5, wherein the length of the at least two tines (30) is in the range of 2 mm to 10 mm and / or the length of the electrode (24) is 5 mm or less, each length being determined in the direction of the longitudinal axis (26) of the intracardiac device.
7. The intracardiac device of claim 4 or 5, wherein the diameter of the distal ends (32) of the at least two tines (30) is in the range of 1 mm to 3 mm.
8. 6. The intracardiac device of claim 4 or 5, wherein the distal end sections of the at least two tines (30) are curved so that their farthest ends point towards the electrode (24).
9. The intracardiac device of claim 4 or 5, wherein the distal end section of one or more of the at least two tines comprises one or more barbs.
10. The intracardiac device of claim 4 or 5, wherein the tines have a proximal section and a distal section, the proximal section being straight and parallel to the longitudinal axis of the intracardiac device, and the distal section being shaped as a hook.