Multilevel electrode

Abstract

The present invention relates to a multi-tiered tip electrode and a pacing device (e.g., leadless or leaded device) that includes a multi-tiered tip electrode and a fixation helix for securing the pacing device at a patient tissue. The shape of the multi-tiered tip electrode in the axial / longitudinal direction stabilizes the attachment to the patient tissue and improves the electrical connection by providing a more effective surface area.

Description

Technical Field

[0001] This invention relates to the field of electrode structures for pacing, sensing and / or communication devices (e.g., capsules, lead devices and / or leadless electrode devices) for cardiac or other pacing and / or sensing systems, such as, but not limited to, left bundle branch (LBB) pacing, cardiac resynchronization or tachycardia (“tachycardia”) systems. Background Technology

[0002] The cardiac conduction system includes the sinoatrial node (SAN), atrioventricular node (AVN), His bundle, bundle branches, and Purkinje fibers. The heartbeat originates in the SAN, which can be considered the heart's natural "pacemaker." Electrical impulses originating from the SAN cause atrial contractions. This signal is conducted to the ventricles via the AVN, where conduction is itself delayed to allow the atria to stop contracting before the ventricles begin to contract, thus providing proper AV synchronization. Electrical impulses are conducted from the AVN to the ventricular myocardium via the His bundle, bundle branches, and Purkinje fibers.

[0003] Patients with conduction system abnormalities (such as poor AV junction conduction or SAN dysfunction) may receive implantable medical devices (IMDs), such as pacemakers, to restore a more normal heart rhythm and AV synchronization. Some types of IMDs, such as pacemakers, implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices, deliver therapeutic electrical stimulation to the patient's heart via electrodes placed in or adjacent to the heart on one or more implantable endocardial, epicardial, or coronary vein leads. This therapeutic electrical stimulation can be delivered to the heart in the form of pulses or electric shocks for pacing, cardioversion, or defibrillation. In some cases, IMDs can sense the heart's inherent depolarization and control the delivery of therapeutic stimulation to the heart based on this sensing.

[0004] Left bundle branch pacing (LBBP) has emerged as an alternative method for delivering physiological pacing to achieve electrical synchronization of the left ventricle (LV), particularly in patients with subnodal atrioventricular block and / or left lateral bundle branch block (LBBB). The proximal LBB crosses the LV septum and spreads out, forming a wider pacing target compared to the His bundle. An LBBP technique using a transventricular approach (i.e., pacing the LV from the RV) has been developed. LBBP has been reported to provide a low pacing threshold and large R waves, and because it targets the distal conduction system, the theoretical risk of distal conduction block is lower.

[0005] After determining the initial location of the LBBP on the right surface of the ventricular septum, a helical fixation element is screwed into the LV septum, for example, by puncturing the tissue with the distal end of the helical fixation element (fixation spiral). The depth of insertion into the LV septum can be determined by one or more of the following: observed changes in the V1 lead notch, sheath angiography, fulcrum sign, and impedance monitoring. By applying torque, the pacing electrode is slowly advanced to the determined depth of the septum (e.g., approximately 8 to 12 mm) while avoiding LV-side perforation of the septum. Finally, LBB capture is confirmed based on acceptable pacing parameters. Such confirmation can be based on at least one of the following: pacing morphology of the RBBB pattern, recording of the LBB potential, peak stimulation of the LVAT (which shortens abruptly with increasing output or remains shortest and constant at low and high output), selective and non-selective LBBP, and recording of retrograde or forward LBB potentials during pacing.

[0006] The ends of pacing or tachycardia leads are typically designed to avoid the risk of septal perforation. They may also be equipped with soft ends (made of, for example, silicone) to increase the stopping surface. That is, when the helical fixing element or electrode (hereinafter referred to as the "helix") engages with (e.g., screwed into) (cardiac) tissue, the tissue is pushed toward the soft end to stop the helix from rotating and advancing further within the tissue. The length of the helix can be limited to, for example, an effective length of about 2 mm.

[0007] In lead-based LBBP techniques, common features of the implantation or placement process include transvenous access, placement of the pacing lead through the interventricular septum into the subendocardium of the LBB region, and confirmation of LBB capture as described above.

[0008] As an alternative, leadless techniques have been developed in which a leadless medical device (e.g., a capsule) with a spiral, for example, is implanted in the apex region, more preferably in the lower septum, to limit the risk of perforation of a thin apex. The capsule is typically 35 mm in length, including the spiral (2 mm). This capsule can be delivered via a vascular catheter introduced through the femoral artery.

[0009] Leadless capsules may require a fixed system and two electrodes (the end and the loop), where the electrodes are key to electrical performance and low power consumption (minimum stimulation threshold). Summary of the Invention

[0010] The purpose of this invention is to provide an improved electrode and fixation system.

[0011] This objective is achieved by the terminal electrode according to claim 1 and the pacing device according to claim 9.

[0012] Therefore, two or more axially projecting contact areas between the end electrode (e.g., cathode) and the patient's tissue improve the strength and efficiency of tissue contact and minimize tissue damage. Furthermore, the improved shape factor and optional coating of the proposed end electrode enhance electrical connectivity, providing a more effective contact surface even in the event of slight capsule displacement. Thus, the attachment of the capsule to the myocardium or other patient tissue can be safely and stably secured without causing serious damage to the heart or other body parts.

[0013] According to the first option, the prominent tissue contact area can be configured as a closed or open circular or polygonal ring or annular segment, or a prominent pattern arranged in the shape of a closed or open circular or polygonal ring or annular segment, which may be arranged around the central axis of the pacemaker or may not be arranged around the central axis of the pacemaker.

[0014] According to the second option, the end electrode may include a cylindrical body, wherein the axially projecting tissue contact area may include an outer ring and an inner ring.

[0015] According to the third option, the inner ring can be formed on top of the outer ring in the distal direction.

[0016] According to the fourth option, a coating that improves contact, particularly a TiN coating, can be applied to the protruding tissue contact area of ​​the cylindrical body.

[0017] According to the fifth option, which can be combined with any of the first to fourth options, the protruding tissue contact area can be arranged around the central hole of the end electrode, or it can be arranged outside the central hole of the end electrode.

[0018] According to option six, the central pore can be at least partially filled with steroids.

[0019] According to option seven, additional steroid portions can be placed around the prominent tissue contact area.

[0020] According to the eighth option, which can be combined with any of the first to seventh options, the pacing device may include a cone-shaped fixed helix, wherein the diameter of the coils of the cone-shaped helix may be increased in the distal direction to obtain a cone shape.

[0021] According to option nine, the maximum diameter of the spiral coil at the distal end of the conical helix can be configured to match the diameter of the cylindrical shell of the device.

[0022] It should be further understood that the preferred embodiments of the present invention may also be any combination of the dependent claims or the above embodiments and the corresponding independent claims.

[0023] These and other aspects of the invention will be shown and illustrated with reference to the embodiments described below. Attached Figure Description

[0024] In the following figures: Figure 1 The heart is schematically shown, with corresponding placement options for leaded and leadless devices for ventricular transseptal LBB pacing. Figure 2 A perspective side view of the double-ring end electrode according to the first embodiment is shown schematically; Figure 3 schematically shown Figure 2 Side view and cross-sectional side view of the double-ring end electrode, with additional through-hole and dimensional parameters; Figure 4 A perspective top view of a bicyclic terminal electrode with integrated steroids according to a second embodiment is schematically shown. Figure 5 A schematic perspective top view of a wireless capsule having a double-ringed end electrode and a conical helix according to a third embodiment is shown; and Figure 6 A schematic perspective side view of a leadless pacemaker is shown, in which a dual-ring terminal electrode can be implemented. Detailed Implementation

[0025] Various embodiments of the invention are now described based on leadless medical pacing, sensing, and / or communication devices (e.g., capsules) with multi-level terminal electrodes. While the invention is particularly advantageous in the context of leadless pacing devices for transseptal pacing (such as LBBP), it is not limited thereto and can be used in conjunction with any type of pacing, sensing, and / or communication lead and / or other pacing types and / or other sites where pacing devices need to be placed within body tissue.

[0026] It is worth noting that throughout this disclosure, only those elements, parts, components, and / or devices related to the proposed pacing device and placement operation are shown in the accompanying drawings. For the sake of brevity, other elements, parts, components, and / or devices may have been omitted. Furthermore, components designated with the same reference numerals or numbers are intended to have the same or at least similar functions, and therefore their functions will not be described further below.

[0027] Furthermore, throughout this disclosure, the terms "proximal" and "distal" are used to indicate the distance from the operating tip (reference point) of the pacemaker, where a physician or other user controls the rotation process. Proximal refers to being closer to the operating tip, while distal refers to being farther away (larger distance) from the operating tip.

[0028] As used herein, “leadless” means that a medical device (such as a pacing, sensing, and / or communication device) does not have any one or more leads extending from the medical device to the patient’s heart. Some leadless devices can be introduced via a vein, but once implanted, such devices have no (or may not include) any transvenous leads and can be configured to provide cardiac treatment without the use of any transvenous leads.

[0029] As used in this article, "axial" direction or length refers to the longitudinal axis of the pacemaker and / or the fixation spiral used to secure the pacemaker to the patient's tissues.

[0030] Figure 1 A heart with an inserted lead device 200 is schematically shown, in which the pacing lead tip 20 is placed for transseptal ventricular LBBP. Furthermore, for comparison, a leadless device (capsule) 400 is also shown, its helix 300 not yet inserted into the septum 24. Thus, LV pacing can be performed from the RV via a transseptal ventricular approach. The placement of the pacing lead tip 20 can be based on the procedure briefly explained in the above-mentioned introduction. LBBP can be defined as the capture of the LBB (i.e., the left bundle trunk or its proximal branch), typically at low output (e.g., <1.0 V / 0.4 ms) of the septal myocardium.

[0031] It is worth noting that, with Figure 1 Conversely, the pacing lead tip 20 and the leadless device 400 are not intended for simultaneous use. They can be used as alternatives depending on the patient's condition / symptoms.

[0032] As described in the introduction, in normal cardiac function, the heartbeat begins on the heart itself, thanks to the SAN, located at the top of the right atrium (RA) (i.e., the neck / head region facing the body) and setting the frequency of the heart's contractions. It emits electrical impulses that are transmitted through the muscular walls of both atria. These impulses cause atrial contractions. The impulses are then passed to another node inside the heart—the AVN. This node is located in the lower part of the RA, within the subendocardial layer of the atrial septum wall, which separates the RA from the left atrium (LA). Once the impulses from the SAN reach the AVN, they are transmitted to the conduction fibers, which propagate downwards along the central wall of the heart. The impulses then branch and propagate upwards to the LV and RV, causing them to contract, with a natural delay between the contractions of the LV and RV (ventricular systole).

[0033] The vital components of the cardiac conduction system are located within septum 24. The His bundle proceeds subendocardially, descending approximately 1 cm to the right of septum 24, before dividing into the LBB and RBB. The LBB continues descending to the right of septum 24, while the LBB crosses to reach the left side and branches into the anterior and posterior fasciculi.

[0034] Normally, the activation of the sinus rhythm controls the heart rhythm. Abnormalities in sinus rhythm can lead to arrhythmias, which are abnormalities in the rate, rhythm, origin, and conduction of cardiac electrical impulses. When there is a disorder in the conduction fibers of a specific ventricle, the repolarization wave must then travel through slower intermuscular conduction to reach the ventricle. Classic disorders associated with conditions involving different conduction branches include LBBB and RBBB. An electrocardiogram (ECG), obtained through the insertion of a lead device, is used to measure and record the heart's electrical activity, thus providing important information about cardiac function. ECG has been used as a standard diagnostic tool for analyzing arrhythmias.

[0035] In one or more embodiments, the pacing device for bundle pacing is a leadless device that can be operatively connected to electrodes positioned near the septum without the use of leads when the device housing is placed in the RV. However, it should be noted that in embodiments, the pacing device (e.g., a capsule or lead) may also be placed in the RA. The helix can be connected to the housing of the leadless device without the need for leads between the electrodes and the housing. The leadless device (i.e., the implemented medical pacing device) can sense electrical signals accompanying cardiac depolarization and repolarization via a terminal electrode at the distal end of the body of the leadless device and optionally via a terminal electrode at the fixed helix. In some instances, the leadless device can deliver pacing pulses to the heart based on electrical signals sensed within the heart. The electrode configuration for sensing and / or pacing can be unipolar (e.g., in the case of a lead device) or multipolar (e.g., in the case of a leadless capsule or lead device). The lead assembly can be a conventional lead with a single pole (monopolar) that is connected to the housing / shell of a pacemaker / defibrillator, wherein the housing / shell becomes a second pole for sensing and / or pacing.

[0036] Leadless devices can also deliver defibrillation and / or cardioversion therapy via one or more electrodes based on detected cardiac arrhythmias (such as ventricular fibrillation), for example, by delivering defibrillation therapy to the heart in the form of electrical pulses. In some instances, leadless devices can be programmed to deliver progressive therapy, for example, with pulses of increasing energy levels until the fibrillation stops. For this purpose, leadless devices can employ one or more fibrillation detection techniques known in the art to detect fibrillation.

[0037] The leadless device may include an intracardiac housing comprising sensing circuitry operatively coupled to electrodes (i.e., distal electrodes) and configured to sense one or both of atrial and ventricular events using those electrodes. Furthermore, the housing may include an electrical pulse generator coupled to bundle branch pacing electrodes (i.e., distal electrodes), configured to generate and deliver bundle branch pacing electrical pulses to the patient's heart based on one or both of atrial and ventricular events using the bundle branch pacing electrodes. The housing may also include a communication interface configured to receive control signals. The leadless device may further include a controller disposed within the housing and operatively coupled to the pulse generator for controlling the delivery of bundle branch pacing pulses to the patient's heart in response to the received control signals.

[0038] The embodiments of the terminal electrode and the fixed helix of the proposed pacing device (i.e., leadless device) are configured to maximize the contact area of ​​the terminal electrode and improve its contact efficiency.

[0039] In implementation, this can be achieved by configuring the shape of the distal electrode surface to provide two or more axially projecting tissue contact areas with different axial (longitudinal) levels at the distal end of the distal electrode. In examples, the projecting tissue contact areas can be configured as closed or open circular or polygonal rings or annular segments, or as projecting patterns arranged in the shape of closed or open circular or polygonal rings or annular segments. Two or more closed and / or open polygonal and / or circular rings and / or annular segments and / or patterns can be concentrically arranged on the distal electrode around the central axis of the pacemaker. This multi-level distal electrode provides an enhanced tissue contact surface area for improved electrode performance.

[0040] In the first embodiment, protruding tissue contact areas with different axial levels are configured as two concentric rings with different thicknesses, which are stacked one on top of the other to obtain a double-ring end electrode.

[0041] Figure 2 A perspective side view of the double-ring end electrode 20 according to the first embodiment is shown schematically.

[0042] The proposed dual-ring end electrode 20 includes a cylindrical body 26, the top of which may be coated with a TiN coating, and on which two axially protruding rings 22 and 24 are disposed. The two axially protruding rings include a thicker outer (lower-level) ring 22, on which a thinner inner (upper-level) ring 24 is formed.

[0043] The dual-ring distal electrode 20 has an increased distal contact surface area, ensuring improved tissue contact to maintain better tissue contact during patient movement with an implanted pacemaker. This improved tissue contact offers the advantage that the distal electrode can adequately reach cardiac tissue to examine the electrical properties of the implantation site without the need for implantation of a capsule with the distal electrode, or before implantation of a capsule with the distal electrode. Therefore, the capsule can be implanted at a suitable site with the required electrode properties, for example, to ensure less tissue damage.

[0044] Figure 3 schematically shown Figure 2 The image shows a side view of the double-ring end electrode and cross-sectional side views from different angles (offset by 90 degrees), with a through-hole added to the electrode body. This through-hole can be provided to attach the double-ring electrode to the capsule (not shown) via a screw, pin, spring pin, or bolt fixing mechanism. Other fixing methods (e.g., welding, gluing, etc.) can also be used.

[0045] In one example, the diameter of the central axial through-holes within the two rings 22 and 24 can be approximately 0.9 mm, the diameter of the cylindrical body of the double-ring end electrode 20 is approximately 1.6 mm, and the height H1 of the cylindrical body is approximately 1.3 mm. Furthermore, the radius R1 of the outer surface of the outer ring 22 can be approximately 1 mm, the radius R2 of the inner surface of the outer ring 22 can be approximately 0.5 mm, and the radius R3 of the inner ring can be approximately 0.6 mm. The height H2 of the inner ring 24 can be approximately 0.1 mm. Additionally, the diameter D of the fixed through-hole can be approximately 0.3 mm.

[0046] Other sizes may be selected depending on the application and conditions of the implantation and / or pacing site.

[0047] The through-hole at the center of the two rings 22 and 24 may have at least one of the following possible functions: It may be at least partially filled with steroids or other drugs, and / or it may ensure that the end electrode has a double-ring shape rather than a cup shape, and / or Even at the inner edge of the inner ring 24, it can provide better contact with cardiac tissue or other patient tissues.

[0048] Figure 4 A perspective top view of a bicyclic terminal electrode with integrated steroids according to a second embodiment is shown schematically.

[0049] Steroid 44 at the center of the dual-ring terminal electrode can be used to reduce fibrosis. Steroids are drugs that can reduce fibrosis around damaged tissue areas, which may be caused by the twisting operation of the fixation helix during the attachment of a pacemaker (e.g., a capsule) to the dual-ring terminal electrode.

[0050] like Figure 4As shown, design variants can integrate additional steroids 46 around the outer ring 22 to provide steroids 44, 46 on both sides of the dual-ring terminal electrode, thereby ensuring better tissue quality and generating electrical contact between the pacemaker and myocardial tissue or other patient tissues.

[0051] Figure 5 A schematic perspective top view of the end portion of a leadless capsule according to a third embodiment is shown, the capsule having a double-ring end electrode 20 and a conical helix 50.

[0052] To achieve the required quality and / or integrity of electrical contact between one or more output connections / interfaces (not shown) of the leadless capsule and the dual-ring end electrode 20, a permanent and robust connection can be established (e.g., by screwing, welding, crimping, etc.). Furthermore, if the conical helix 50 also includes end electrodes, the proximal portion of the conical helix 50 can be mechanically secured to the housing 54 of the leadless capsule and can then optionally be connected to internal electronic circuitry (e.g., via feedthrough technology, which also ensures an hermetically sealed housing).

[0053] The diameter of the spiral coils in the conical helix 50 increases distally to achieve a conical shape. This conical shape, with the diameter of the spiral coils widening distally, allows the leadless capsule to better attach to myocardial tissue while compressing the tissue toward the dual-ring terminal electrode 20. This, combined with the improved effective surface area achieved by the dual-ring electrode 20 or any other type of proposed multi-level terminal electrode, provides a synergistic effect.

[0054] The maximum diameter of the coil at the distal end of the conical helix 50 can be selected to match (substantially) the diameter of the capsule shell 54, thereby facilitating smooth implantation of the capsule during tissue perforation. Furthermore, the coil of the conical helix 50 may include an insulating surface to prevent undesirable electrode function. The insulating surface can be achieved by covering the coil with a dielectric or other insulating material.

[0055] In addition, a protective ring with a radially protruding protective element 52 can be provided at the proximal end of the conical spiral 50 to prevent the conical spiral 50 from spiraling out of the patient's tissue along with the capsule.

[0056] Alternatively, a non-conductive (e.g., non-metallic) insulating ring 56 may be provided to insulate the end electrode 20 from the conical helix 50.

[0057] Optionally, to provide additional cathode functionality to the LBBP, the spiral coils of the distal segment of the conical helix 50 may be left uninsulated by any non-conductive covering or isolation. In one example, the surface of the spiral coils of the uninsulated distal segment may be coated with classic TiN (titanium nitride) to optimize electrical properties. Furthermore, the distal segment may be configured to provide X-ray visibility to help physicians precisely position the cathode within the width of the septum.

[0058] In this configuration, if two terminal electrodes are used (one at the distal end of the helical body 50 and the other at the double-ring electrode 20), the double-ring terminal electrode 20 can be used as an (additional) RV cathode. If the double-ring terminal electrode 20 is used in combination with the helical terminal electrode, independent LV / RV pacing with a controlled delay between stimulations of the two chambers can be implemented.

[0059] The conical helix 50 can be made using classic windings of one or more insulated wires (e.g., for the inner conductor of a wire assembly, which has windings of 4 to 6 individual wires).

[0060] Figure 6 A schematic perspective side view of a leadless capsule (as an example of a lead device or pacing device) is shown, in which the dual-ring terminal electrode 20 of the above-described embodiment is implemented.

[0061] The leadless capsule includes a housing 130 having or defining an outer wall 135 (a cylindrical outer wall shown in the figure) extending from a distal end region 132 of the housing to a proximal end region 134 of the housing. The housing 130 may enclose electronic circuitry configured to perform single-chamber or multi-chamber cardiac therapy, including atrial and ventricular cardiac electrical signal sensing and pacing of the atrial and ventricular chambers. A delivery tool interface member 126 may be disposed on the proximal end region 134 of the housing.

[0062] Furthermore, the distal fixation and electrode assembly 136 may be connected to the distal end region 132 of the housing. The distal fixation and electrode assembly 136 may include an electrically insulating distal member 172 coupled to the distal end region 132 of the housing. The electrically insulating distal member 172 includes a double-ring end electrode 20 and a fixing helix 112 extending from the distal end region 132 of the housing. The fixing helix 112 extends longitudinally from the distal end region 132 of the housing and may be coaxial with the longitudinal central axis 131 of the housing 130.

[0063] The fixing helix 112 may include an electrically insulating rod 140, which also serves as a fixing member. It may optionally include a distal cathode terminal electrode element (not shown). The proximal end region of the rod of the fixing helix 112 may be directly coupled to the insulating distal member 172. The helical rod 140 may be coated with an electrically insulating material, such as parylene, to avoid sensing or stimulating cardiac tissue along its axial length.

[0064] The dual-ring terminal electrode 20 can be used as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals, using a proximal housing-based electrode 124 as a return anode. The proximal housing-based electrode 124 can be an annular electrode surrounding the housing 130 and can be defined by an uninsulated portion of the longitudinal sidewall 135. Other non-electrode portions of the housing 130 can be coated with an electrically insulating material.

[0065] In embodiments, multiple cathodes (e.g., the terminal electrode of the fixed helix 112 and the double-ring terminal electrode 20) may be used for bipolar or multipolar sensing or pacing. These multiple cathodes may include tissue-penetrating electrodes (e.g., the fixed helix 112 or a straight dart-shaped or needle-shaped electrode) and non-tissue-penetrating electrodes (e.g., the double-ring terminal electrode 20) located at the periphery of the insulating distal member 172. The insulating distal member 172 may define a distally facing surface 138 of the capsule and a circumferential surface 139 surrounding the capsule and abutting the longitudinal sidewall 135 of the shell.

[0066] As the fixed helix 112 is advanced into the heart tissue, the dual-ring terminal electrode 20 makes close contact with the heart tissue surface for delivering pulses and / or sensing electrical signals generated by the patient's heart. The dual-ring terminal electrode 20 can be coupled to a treatment delivery circuit and a sensing circuit enclosed by a housing 130 to act as a cathode electrode for delivering atrial pacing pulses and for sensing atrial electrical signals (e.g., P waves), used in combination with a proximal housing-based electrode 124 (as a return anode). Switching circuitry included in the sensing circuitry can be activated under the control of a control circuitry to couple the dual-ring terminal electrode 20 to an atrial sensing channel. Switching circuitry included in the treatment delivery circuitry can be activated under the control of a control circuitry to couple the dual-ring terminal electrode 20 to the atrial pacing circuitry.

[0067] In the above embodiments, the housing of the leadless device (e.g., a leadless pacemaker) can be made of a plastic material such as polyetheretherketone (PEEK) due to its high biocompatibility and excellent mechanical rigidity. Alternatively, the housing of the leadless device 40 can also be made of titanium (to achieve, for example, X-ray transparency, weldability, desired mechanical and biological properties), and coated with an insulating coating such as parylene or ethylene tetrafluoroethylene (ETFE). Optionally, an additional safety insulating layer can be added to the housing to enhance electrical insulation and improve the housing's abrasion resistance.

[0068] In summary, this paper describes a multi-level end electrode and capsule (e.g., including but not limited to leadless pacing and / or sensing devices) comprising a multi-level end electrode and a fixation spiral for securing the pacing device to patient tissue. The multi-level shape of the end electrode in the axial / longitudinal direction of the capsule stabilizes attachment to patient tissue and improves electrical connectivity by providing a more efficient surface area.

[0069] Although the invention has been shown and described in detail in the accompanying drawings and the foregoing description, such showing and description should be considered illustrative or exemplary rather than limiting. The invention is not limited to the disclosed embodiments of the end electrode with a double-ring configuration. Any other multi-level shape having circular or polygonal rings or annular segments or annular patterns is intended to be covered. Multi-level end electrodes can be applied to various types of pacing devices (e.g., bradycardia or tachycardia leads with multi-chamber, coaxial, or co-radial structures) and cardiac pacing or sensing systems to reduce the space required before and / or after insertion of the fixation helix.

[0070] More specifically, the proposed multi-level end electrodes, with or without conical helices, can be used in combination with various lead assembly designs that can have multi-cavity, coaxial, and co-radial structures, serving as tachycardia leads or bradycardia leads, and providing a central cavity for the lead passage. Coaxial leads have an inner conductor extending downwards along the length of the lead to the end electrode (helix), i.e., the cathode, which is arranged to provide a coil configuration for the central cavity, for example, to allow the lead to pass through during implantation. Multi-cavity or coaxial or co-radial leads may optionally include a fixed, non-retractable helix to minimize size. However, retractable helices may also be used in conjunction with the described embodiments.

[0071] Furthermore, the lead system with the proposed multi-level end electrodes can be configured to provide improved torque capability, i.e., the ability to safely and accurately transmit torque to the helix (e.g., full lead body torque) and compatibility with the core drive to simplify manipulation (e.g., by push transmission). In one example, lead wires of the same diameter with screwdriver-compatible cores can be provided.

[0072] The capsule with the proposed multi-level end electrodes can be configured to adapt to or be adaptable to IS1, IS4 (low voltage) or DF4 (high voltage) connectors.

[0073] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plural. The fact that certain measures are recited in mutually different dependent claims does not mean that combinations of these measures cannot be used advantageously. The foregoing description details certain embodiments of the invention. However, it should be understood that the invention can be implemented in many ways, and is therefore not limited to the disclosed embodiments, no matter how detailed the foregoing may appear in the text. It should be noted that the use of specific terms in describing certain features or aspects of the invention should not be construed as implying that such terms are redefined herein to limit any particular characteristic of the invention's features or aspects associated with that term.

Claims

1. A terminal electrode (20) for a pacing, sensing and / or communication device, the terminal electrode (20) being configured to be mounted on a distal end of the device and including a distal surface having two or more axially projecting tissue contact areas (22, 24) at the distal end of the terminal electrode (20) having different axial levels.

2. The end electrode (20) according to claim 1, wherein, The prominent tissue contact areas (22, 24) are configured as closed or open circular or polygonal rings or annular segments, or as prominent patterns arranged in the shape of closed or open circular or polygonal rings or annular segments.

3. The end electrode (20) according to claim 1 or 2, comprising a cylindrical body (26), wherein, The axially protruding tissue contact areas (22, 24) include an outer ring (22) and an inner ring (24).

4. The end electrode (20) according to claim 3, wherein, The inner ring (24) is formed on the outer ring (22) in the distal direction.

5. The end electrode (20) according to claim 3 or 4, wherein, The cylindrical body (26) is coated with a coating to improve contact, particularly a TiN coating, at the protruding contact areas (22, 24).

6. The end electrode (20) according to any one of the preceding claims, wherein, The prominent tissue contact areas (22, 24) are arranged around the central hole of the terminal electrode (20).

7. The end electrode (20) according to claim 6, wherein, The central hole is at least partially filled with steroids (44).

8. The end electrode (20) according to claim 7, further comprising additional steroid portions (46) surrounding the protruding contact areas (22, 24).

9. A pacing, sensing and / or communication device comprising the terminal electrode (20) of any of the preceding claims.

10. The apparatus according to claim 9, further comprising a conical fixed helix (50), wherein, The diameter of the spiral coil of the conical helix (50) increases in the distal direction to obtain a conical shape.

11. The apparatus according to claim 10, wherein, The maximum diameter of the spiral coil at the distal end of the conical helix (50) is configured to match the diameter of the cylindrical housing (54) of the device.

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