Extendable fixing spiral for electrode fixation

Abstract

The present invention relates to a pacing device comprising a distal fixing helical body for fixing a pacing device (e.g., a leadless capsule) to patient tissue, wherein the fixing helical body has an extendable section that extends as the fixing helical body is screwed into the tissue, thereby reducing the space required for insertion and allowing the pacing device to be positioned in a bent state to minimize undesirable mechanical interactions.

Description

Technical Field

[0001] The present invention relates to the field of fixation structures for pacing devices (e.g., electrode catheters and / or leadless electrode devices) for cardiac pacing systems, such as, but not limited to, left bundle branch (LBB) pacing, cardiac resynchronization, or tachycardia ("tachy") systems.

Background Art

[0002] Different electrical activation sequences in cardiac pacing can result in different mechanical pumping efficiencies in the stimulated heart. What is necessary to optimize pumping efficiency is rapid and uniform contraction of the ventricles.

[0003] Conventional pacing sites, such as the right ventricular apex (RVA), provide a stable lead position with a low displacement rate, but are not very effective in optimizing left ventricular (LV) contraction (which accounts for about 80% of the cardiac mass). Long-term RVA pacing may have an adverse effect on LV function by inducing iatrogenic left bundle branch block (LBBB), which can strongly affect the hemodynamic performance of the left ventricle. This observation has motivated the reevaluation of conventional approaches and the study of alternative pacing sites to obtain a more physiological pattern of ventricular activation and avoid adverse effects.

[0004] Left bundle branch pacing (LBBP) has emerged as an alternative method to provide physiological pacing to achieve electrical synchronization of the LV, particularly in patients with infra-Hisian block and / or LBBB. The proximal LBB passes through the LV septum and spreads fan-like to form a wider pacing target compared to the His bundle. Techniques for LBBP have been developed using a transseptal approach to the ventricles (i.e., pacing the LV from the RV). LBBP has been reported to provide a low pacing threshold and a large R wave, and has a low theoretical risk of distal conduction block because the distal conduction system is targeted.

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

[0006] It should be noted that the inner surface of the lumen in the RV and LV is "covered" by a thin, tough skin (membrane or lining) called "endothelium," which is far tougher to puncture than the inner portion of the septum. The tips of pacing or tachycardia leads are typically designed to avoid the risk of septal perforation. They may also have a soft tip (e.g., made of silicone) to enlarge the stopping surface. That is, when the helical fixation element or electrode (hereinafter referred to as the "helical body") engages with (e.g., screwed into) (cardiac) tissue, this tissue is pressed against the soft tip to prevent the helical body from rotating and advancing further into the tissue. The length of the helical body may be limited to an effective length of, for example, about 2 mm.

[0007] In lead-based LBBP technology, common features of the implantation or placement process include transvenous access, transseptal placement of the pacing lead to the LV septal subendocardium in the LBB region, and confirmation of LBB capture as described above.

[0008] As an alternative, leadless technology has been developed in which a leadless medical device having a helical body (e.g., a capsule) is implanted in the inferior septum to reduce the risk of perforation in the apical region, more preferably in the thin apex. The typical length of the capsule is 35 mm, including the helical body (2 mm). This capsule can be delivered via a vascular catheter introduced through a femoral access.

[0009] However, the delivery of a leadless device (e.g., a capsule) to the upstream third of the septum is a difficult process requiring access through sharp bends and kinks before engaging with the tissue. This challenge becomes even more severe as the length of the leadless capsule (including the helical body) increases. Another adverse effect of placing and leaving a leadless capsule in this position is that the permanent mechanical interaction between the implanted capsule and the tricuspid valve can cause turbulence in blood flow. [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide an improved electrode fixation system that requires less space and / or can reduce undesirable mechanical interactions with internal cardiac structures. [Means for solving the problem]

[0011] This objective is achieved by the pacing device described in claim 1, the method for manufacturing a fixed helical body described in claim 11, and the method for manufacturing a lead pacing device described in claim 14.

[0012] The proposed placement and insertion of the pacing device into the patient's tissue requires less space both before and after insertion, and reduces the space required during insertion by reducing undesirable mechanical interactions through an extendable section that extends as the fixed spiral is screwed into the tissue, allowing the device to be positioned in a bent state (i.e., in a curved or curved structure) to minimize undesirable and harmful mechanical interactions.

[0013] According to the first option, the extendable section of the fixed helix can be positioned at least partially around the housing of the pacing device (or its turn can be wound / shifted) to partially position the fixed helix around the housing or shift it over the housing (i.e., its turn can be wound around the housing), which may give the device a shorter longitudinal length, at least when the device is in its initial non-extended state, compared to currently available devices. Furthermore, by providing a fixed helix positioned / wound around the housing of the pacing device (e.g., capsule), a structural surface is formed that promotes and supports the growth of fibrous tissue, which can contribute to the long-term mounting stability of the device within the ventricle. The fibrous growth around the pacing device becomes more rapid and robust due to the tissue response to continuous physical contact with the device, particularly when the heart beats, resulting in better fixation of the pacing device in cardiac tissue (e.g., septum).

[0014] According to the second option, which can be combined with the first option, the helical turns of the extendable section are insulated by an insulating coating, and at least one helical turn of the rigid section may be left uninsulated to form a pacing electrode. This allows the distal portion of the fixed helical body to be used as a pacing electrode, eliminating the need for additional pacing electrodes and corresponding wiring.

[0015] According to a third option that can be combined with the first or second option, the fixed helical body has at least two separate helical wire structures, each having helical turns arranged alternately in the axial direction of the fixed helical body, the first of the helical wire structures having a rigid section, and the second of the helical wire structures having at least one non-insulated helical turn located proximal to the rigid section to form a second pacing electrode. By providing two pacing electrodes on the fixed helical body in this way, a dual pacing mode can be realized.

[0016] According to a fourth option, which can be combined with any of the first to third options, the extendable section may have a subsection having predetermined bending properties such that when the fixed helical is screwed into the patient's tissue, the pacing device is (essentially) pressed against the surface of the patient's tissue (the device is mounted substantially parallel to the septum). This further reduces space requirements by ensuring that the pacing device is positioned parallel to the surface of the patient's tissue (e.g., the septum) after insertion of the fixed helical.

[0017] According to a fifth option that can be combined with the fourth option, a predetermined bending property of a subsection can be brought about by partially increasing the cross-sectional width of the helical turn of the subsection in the axial direction of the fixed helical body. This allows the predetermined bending property to be easily provided, for example, by forming a helical turn with the desired shape using a simple three-dimensional laser cutting process.

[0018] According to the sixth option, which can be combined with the fourth or fifth option, the subsection may have a helical turn in which the cross-sectional width of the fixed helical body changes in the radial direction. This allows the extension characteristics of the extendable section of the fixed helical body to be controlled individually.

[0019] According to the seventh option, which can be combined with any of the first to sixth options, the pacing electrode can be provided at the distal end of the housing of the pacing device. Thereby, a second pacing electrode can be provided on the proximal side to enable a dual pacing mode.

[0020] According to the eighth option, which can be combined with any of the first to seventh options, an axially elongated X-ray marker can be provided on the side of the housing of the pacing device. Thereby, during or after the insertion of the fixation helix, the appropriate position of the pacing device body can be confirmed through X-ray imaging diagnosis.

[0021] According to the ninth option, which can be combined with any of the first to eighth options, the pacing device can be a leadless device for fascicular pacing. Thereby, the size of the pacing device can be better adapted to the individual space requirements within the patient's RV.

[0022] According to the tenth option, which can be combined with any of the first to ninth options, a sub-section having predetermined bending characteristics can be formed in the manufacture of the fixation helix by obtaining the predetermined bending characteristics using a laser tube cutting process or heat treatment. Thereby, the predetermined bending characteristics can be easily controlled in the manufacture of the fixation helix or the pacing device.

[0023] Furthermore, it should be understood that the preferred embodiments of the present invention may also be any combination of the dependent claims or the above embodiments and the individual independent claims.

[0024] These and other aspects of the present invention will be clearly described by referring to the embodiments described below.

Brief Description of the Drawings

[0025] [Figure 1] A schematic diagram of the heart showing the arrangement of the lead device and the leadless device for ventricular transseptal LBB pacing. [Figure 2] In a leadless device having an extendable fixation helix according to the first embodiment, a diagram schematically showing a side cross-section before the extendable fixation helix is punctured into the septum. [Figure 3] In the leadless device having the extendable fixation helix of FIG. 2, a diagram schematically showing a side cross-section after the extendable fixation helix is punctured into the septum. [Figure 4] In a leadless device having an extendable fixation helix according to the second embodiment provided with a multi-spiral wire structure, a diagram schematically showing a side cross-section after the extendable fixation helix is punctured into the septum. [Figure 5] In a leadless device having a pre-bent extendable fixation helix according to the third embodiment, a diagram schematically showing a side cross-section after the extendable fixation helix in a bent state is punctured into the septum. [Figure 6] In a leadless device having an extendable fixation helix with a radially varying thickness along the longitudinal direction according to the fourth embodiment, a diagram schematically showing a side cross-section after the extendable fixation helix is punctured into the septum.

Modes for Carrying Out the Invention

[0026] Various embodiments of the present invention are described based on an improved leadless medical pacing device (e.g., a capsule) having an extendable fixation helix. The present invention is particularly useful as a leadless pacing device for transseptal pacing such as LBBP, but is not limited thereto and can also be used in relation to pacing leads and / or other pacing types and / or sites in other applications that require placement of a pacing device within living tissue.

[0027] In this disclosure, only elements, parts, components, and / or devices related to the proposed lead device and placement operation are shown in the accompanying drawings. Other elements, parts, components, and / or devices are omitted for brevity. Furthermore, components designated by the same reference numeral or number are intended to have the same or at least similar functions, and their functions will not be described redundantly.

[0028] Furthermore, throughout this disclosure, “proximal” and “distal” are terms used to indicate the distance from the operating end (reference point) of the lead device controlled by a physician or other user during the screw-in process. Proximal is closer to the operating end, and distal is further from the operating end (the greater the distance).

[0029] In this specification, “leadless” refers to a medical device (e.g., a pacing device) that is attached to a patient’s heart and lacks an extended lead. Some leadless devices are introduced intravenously, but such devices, once implanted, may have no transvenous leads whatsoever and may be configured to treat the heart without the use of any transvenous leads.

[0030] In this specification, "axial" direction or length refers to the long axis of the pacing device.

[0031] Figure 1 schematically shows a heart with an inserted lead device 200, where the pacing lead tip 20 is positioned for transventricular lbBP. For comparison, a leadless device (capsule) 400 is also shown before its helical body 300 is inserted into the septum 24. This allows the LV to be paced from the RV via a transventricular septal approach. The positioning of the pacing lead tip 20 can be performed based on the procedure briefly described above. LBBP can usually be defined as the capture of the LBB (i.e., the left bundle branch or its proximal bundle) with septal myocardial capture at low power (e.g., <1.0V / 0.4ms).

[0032] Please note that, unlike in Figure 1, the pacing lead tip 20 and the leadless device 400 are not intended to be used together. They may be used as alternatives depending on the patient's condition.

[0033] In normal cardiac function, the heartbeat begins in the heart itself, at the sinoatrial node (SAN), located at the top of the right atrium (RA) (i.e., towards the neck / head of the body), which sets the rate at which the heart contracts. The SAN node generates electrical impulses that are transmitted through the muscular walls of both atria. These impulses cause atrial contraction. The impulses are then transmitted to another node in the heart, the atrioventricular node (AVN). This node is located below the RA in the subendocardial layer of the interatrial septum, the cardiac wall separating the RA from the left atrium (LA). When the impulses from the SAN reach the AVN, they are transmitted through conduction fibers running downwards along the central wall of the heart. The impulses then branch and travel upwards to the LV and RV, causing them to contract simultaneously (ventricular contraction).

[0034] Important components of the cardiac conduction system are found within septum 24. The bundle of His runs downwards in the subendocardial layer on the right side of septum 24 for about 1 cm before branching into the LBB and RBB. The LBB continues down the right side of septum 24, while the RBB crosses to the left side and divides into anterior and posterior branches.

[0035] Under normal conditions, excitation from the sinus ventricle (SAN) controls the heart rhythm. Abnormalities in sinus rhythm cause arrhythmias, which manifest as abnormalities in the velocity, rhythm, origin, and conduction of cardiac electrical pulses. When damage occurs in specific intraventricular conduction fibers, repolarization waves are forced to reach the ventricles via slower muscle-to-muscle conduction. Classical arrhythmias associated with conditions involving different conduction bundle branches include LBBB and RBBB. Electrocardiograms (ECGs) obtained from implanted lead devices can be used to measure and record the electrical activity of the heart and can provide important information about cardiac function. ECGs are used as a standard diagnostic tool for analyzing arrhythmias.

[0036] In one or more embodiments, a pacing device for bundle branch pacing is a leadless device that does not use leads to operatively connect to electrodes located near the septum when the device housing is placed in the atrium. The helical body can be connected leadless to the housing of the leadless device without using leads between the electrodes and the housing. The leadless device (i.e., an implanted medical pacing device) can sense electrical signals associated with cardiac depolarization and repolarization via the helical body. In some examples, the leadless device can deliver pacing pulses to the heart based on the electrical signals sensed within the heart. The electrode configuration of the helical body used in the leadless device for sensing and pacing can be unipolar or bipolar.

[0037] Furthermore, a leadless device may provide electrode-mediated defibrillation and / or ventricular resynchronization therapy based on an arrhythmia detected in the heart, such as ventricular fibrillation, by supplying defibrillation therapy to the heart, for example, in the form of electrical pulses. In some examples, a leadless device may be programmed to provide a series of treatments, such as pulses with increasing energy levels until the defibrillation of the heart stops. To achieve this, a leadless device may detect defibrillation using one or more defibrillation detection techniques known in the art.

[0038] The leadless device may comprise an intracardiac housing including a sensing circuit operably connected to electrodes (i.e., helical bodies) and configured to sense either or both atrial and ventricular events using the electrodes. Furthermore, the housing of the leadless device may include an electrical pulse generator connected to bundle branch pacing electrodes (i.e., helical bodies), which is configured to generate and deliver electrical bundle branch stimulation pulses to the patient's heart using the bundle branch pacing electrodes based on either or both atrial and ventricular events. The housing of the leadless device may include a communication interface configured to receive control signals. Furthermore, the leadless device may include a controller located within the housing and operably connected to the pulse generator to control the delivery of bundle branch pacing pulses to the patient's heart in response to received control signals.

[0039] In some examples, a leadless device may be programmed by a handheld computing device, computer workstation, or mobile phone equipped with a user interface that receives input from the user. The user interface may include, for example, a display such as a cathode ray tube (CRT) display, a liquid crystal display (LCD), or a light-emitting diode (LED) display, and a keypad. The keypad may take the form of an alphanumeric keypad or a reduced key set associated with a specific function. Furthermore or alternatively, a peripheral pointing device such as a mouse or touchscreen may be provided to allow the user to interact with the user interface. Through the user interface, the user may select one or more optimized parameters, such as AV delay and / or VV delay.

[0040] Figure 1 shows an exemplary position where the leadless device 400 for LBBP is implanted before the helical body 300 is inserted into the septum 24. As is evident from Figure 1, the entire length of the leadless system (leadless pacing device 400 with a constantly protruding helical body 300) does not conform to the general anatomical structure of the patient's heart and cannot achieve the required angle / position before puncturing the septum 24. Therefore, implantation may cause excessive interaction with the (free) wall of the RV. This can cause significant interference between the tricuspid valve, located between the two right chambers (RVs) of the heart, and the leadless device 400. The tricuspid valve consists of three thin tissue valve membranes (called cusps or leaflets). These valve membranes, when opened, allow blood to flow from the upper right chamber of the RV to the lower right chamber of the RV.

[0041] Furthermore, the aforementioned incompatible dimensions may seriously hinder the implantation procedure and, in some cases, may prevent the implantation of the leadless device 400 at the desired site. In addition, the total rigid length of the leadless device 400 may not be compatible with the flexibility required for the delivery system to guide it through the desired blood vessel (e.g., a tortuous vein).

[0042] The following embodiments of the proposed pacing device (i.e., leadless device) are configured to minimize adverse effects associated with the placement and insertion of the lead device in and through the septum by providing an extendable fixed helical body that can be extended during the screwing process and / or bent after insertion in order to address and mitigate the above problems (e.g., to facilitate the feeding of the lead device and reduce mechanical interaction with tricuspid valves, etc.).

[0043] Figure 2 schematically shows a side cross-section of a leadless device (capsule (CP)) 40 equipped with a long, extendable fixed helical body 30 according to the first embodiment, before the extendable fixed helical body is punctured into the septum 24.

[0044] To achieve the required quality and / or integrity of the electrical contact between the output connection / interface (not shown) of the leadless device 40 and the cathode of the helical body 30, a permanent and robust connection (e.g., welding or crimping) may be established. For example, the non-movable / non-extendable proximal end of the helical body 30 may be mechanically fixed to the housing of the leadless device 40 and connected to the internal electronic circuitry via a feedthrough technique that also ensures an airtight seal of the housing, for example.

[0045] As can be seen in Figure 2, the extendable fixed helical 30 is fitted into the cylindrical housing (body) of the leadless device 40 (for example, fitted, pushed in, or its turns are wound or wrapped around it). This substantially shortens the overall length of the leadless device 40, including the extendable fixed helical 30, before the helical 30 is inserted into the septum 24, thereby reducing the space required for placement.

[0046] In the example shown in Figure 2, the extendable fixed helical body 30 comprises a first section (S1) having at least one helical turn 34 having an inelastic shape or properties at least in the axial direction of the helical body 30, and an open gap (distance) between the helical turn 34 and a sharp tip (not shown) to facilitate puncture of cardiac tissue in the patient's cardiac septum 24. The length of the first section is in the range of 0.5–3 mm. The first section is configured so that the tip of the extendable fixed helical body 30 engages (punctures, engages) with cardiac tissue and advances the extendable fixed helical body 30 through the septal wall and into the septal tissue through the screwing process. Therefore, the first section may be formed of a rigid material to avoid deformation of the helical body during screwing. LV cathode (C) for LBBP LV To provide the desired functionality, the helical turns 34 of the first section are not insulated by a non-conductive coating or insulator. For example, the surface of the helical turns 34 of the first section may be coated with conventional TiN (titanium nitride).

[0047] It should be noted that the extendable fixed helical body 30 may optionally be formed from two different materials. Since the first section (S1) is intended to function as an electrode (cathode) requiring a surface coating (e.g., TiN) to optimize electrical performance, for example, the distal first section (S1) may be formed from conventional platinum-iridium (Pt-Ir) 90 / 10 or 80 / 20. Furthermore, the distal first section (S1) may be configured to provide X-ray visibility to help the physician accurately position the cathode within the width of the septum 24.

[0048] Furthermore, the extendable fixed helical body 30 includes a long second section (S2) having elastic properties (at least in the axial direction of the helical body 30), which is configured to be reliably connectable to the leadless device 40 at its proximal end to ensure a permanent and reliable electrical connection to the pacing output of the leadless device 40. The length of the second section is in the range of 4–25 mm. Furthermore, in this embodiment, the helical turn 32 of the second section may include an insulating surface (shown as a thick line surrounding the cross-section of the helical turn 32 in Figure 2) to prevent unintentional electrode function. The insulating surface can be achieved by covering the helical turn 32 with a dielectric or other insulating material.

[0049] The second section of the stretchable fixed helical body 30 may be made of an elastic material such as nitinol in order to maintain a high level of elastic deformation and fatigue resistance while allowing X-ray visibility.

[0050] In the example shown in Figure 2, the leadless device 40 has an additional RV cathode (C) mounted as a conductive electrode 50, positioned (e.g., attached or integrated) in the housing of the leadless device 40 at the distal anterior end for independent LV / RV pacing and delay control between stimuli in both chambers. RV ) may have.

[0051] The extendable fixed helical body 30 can be manufactured, for example, using laser tube cutting to enable a "wire" structure of helical turns 32 whose cross-section changes along the helical structure. Laser tube cutting is a process and technique used to cut tubes, structural shapes, or channels. This process cuts these parts to the required length. It can also form holes or designs in the tube. It is a precision cutting technique and can be used on a wide variety of materials of all shapes and sizes. There are various types of laser tube cutting equipment that can handle different cutting needs. A 3-axis laser tube cutter cuts in three dimensions.

[0052] Alternatively, the extendable fixed helical body 30 may be fabricated using one or more conventional coils of insulated wire (for example, to be used as the internal conductor of a lead device having coils of 4-6 individual wires).

[0053] The variable cross section described above facilitates a secure and permanent connection between the proximal or terminal end of the extendable fixed helical body 30 and the pacing output section of the leadless device 40.

[0054] Figure 3 schematically shows a side cross-section of the leadless device 40 equipped with the extendable fixed spiral 30 shown in Figure 2, after the extendable fixed spiral 30 has been inserted into the septum 24.

[0055] Figure 3 shows the LV cathode (C) formed by the helical turn 34 of the non-extendable first section that reaches the pacing region for LBBP in the extendable fixed helical body 30. LVThis is achieved through the axial extension of the second section S2 as the extendable fixed helical body advances through the septum (S) 24 by a screwing motion, and the helical turn 32 of the second section in the extendable fixed helical body 30 is configured to slide distally along the axial direction on the housing surface of the leadless device 40. Optionally, an additional safety insulation layer may be added to the housing of the leadless device 40 to enhance electrical insulation and improve the wear resistance of the housing.

[0056] Since the extendable fixed helical body 30 is manufactured, for example, using laser tube cutting, the variable cross-section wire can be formed along the helical structure of the extendable fixed helical body 30. A full cylindrical structure 38 may be optionally formed at the proximal end to facilitate a secure and permanent connection to the pacing output terminal of the leadless device 40. This provides a proper electrical connection to the pacing output terminal of the leadless device 40.

[0057] Furthermore, the laser tube cutting process can be controlled to form variable cross-sectional wires along the helical structure of the stretchable fixed helical body 30 in order to obtain two subsections S2b and S2a of the elastic second section having different bending properties, as will be described in detail later in relation to Figure 5.

[0058] Figure 4 schematically shows a side cross-section of a leadless device 40 equipped with an extendable fixed helical body 30 having a multi-helical wire structure according to a second embodiment, after the extendable fixed helical body has been punctured into the septum 24.

[0059] The multi-helix wire structure is manufactured, for example, using a laser tube cutting process, and includes at least two coiled / helical wires of the same diameter that form an extendable fixed helical body 30. As shown in Figure 4, the first helical turn 32 of the first helical wire and the second helical turn 36 of the second helical wire are wound alternately and slidably around the housing of the leadless device 40. The distal end of the first helical wire is connected to an LV cathode (C LVThe first non-extendable section of an extendable fixed helical body 30 has at least one non-insulated helical turn 34 forming a RV cathode (C). Furthermore, the distal end of the second helical wire having a second helical turn 36 is connected to the RV cathode (C). RV It is connected to at least one extendable and non-insulated helical turn 35 that forms a ) . This allows the two electrodes (LV cathode and RV cathode) to be embedded in or integrated with the extendable fixed helical body 30.

[0060] Similar to the embodiment in Figure 3, the elastic second section of the stretchable fixed helical body 30 may include at least two subsections S2a, S2b having different bending properties.

[0061] Figure 5 schematically shows a side cross-section of a leadless device 40 equipped with a pre-bent, extendable fixed spiral body 30 according to the third embodiment, after the extendable fixed spiral body 30 has been punctured into the septum 24 in a bent state.

[0062] As already mentioned above, the exemplary laser tube cutting process allows for the formation of a variable cross-section of the helical wire along the structure of the expandable fixed helical body 30. This creates different predetermined bending properties in subsections S2a and S2b of the expandable fixed helical body 30, so that the leadless device 40 lies / rests on the wall of the septum 24 in the RV with its central axis parallel to the plane of the septum surface. As a result, the housing of the leadless device 40 no longer interacts with the column and / or leaflets of the tricuspid valve after the positioning of the leadless device 40 and the insertion of the expandable fixed helical body 30.

[0063] Figure 5 shows the positions the leadless device 40 can take after insertion / tissue puncture. In such positions, a substantial portion of the helical turn 32 of the flexible second section moves axially and slides distally away from the housing, and is no longer positioned around the housing of the leadless device 40, thus freeing a substantial portion of the second subsection S2b of the extendable fixed helical body 30 from the housing. This second subsection S2b is configured to have a predetermined (inherent) bending property, so as to help rotate the long axis of the device housing toward the surface of the septum (S), and this rotation can be approximately 90 degrees. In any case, this rotation helps to orient the device housing so that it is held in contact substantially parallel to the septal wall. Figure 5 shows how the second subsection S2b achieves this predetermined (inherent) bending property or property, where one side of the distal end of the second subsection S2b that forms the outer boundary of the intended bend has a cross section (LCS) that is longer in the axial direction than the corresponding portion that forms the inner boundary of the intended bend.

[0064] The predetermined bending characteristics can also be achieved by a predetermined heat treatment applied to a predetermined portion of the second subsection S2b of the stretchable fixed helical body 30.

[0065] The arrangement of the leadless device 40 having a bent state / orientation close to (parallel to) the septum wall allows the RV cathode (C) to be positioned on the side of the proximal end of the leadless device 40 that contacts the septum wall of the RV when the extendable fixed helical body 30 is in the bent state. RV ) can be advantageously used to arrange the section electrode pattern 60. This allows for a new arrangement of the RV cathode in the third embodiment. Since the contact points after the bending operation are predetermined, the pacing surface of the section electrode pattern 60 can be reduced (e.g., semi-circular section).

[0066] Furthermore, the arrangement of the leadless device 40 in a bent state offers the advantage that the turns of the fixing helical body 30 wrapped around the housing of the leadless device 40 form a structural surface that supports the growth of fibrous tissue. Thus, the growth of fibrous tissue around the leadless device 40 is promoted more quickly and strongly by a tissue response enhanced by the intermittent physical contact of the leadless device 40 (due to the beating of the heart), which results in better fixation of the leadless device 40 to cardiac tissue (e.g., septum). More specifically, fibroblasts and other cells deposit extracellular matrix components such as collagen, forming a "scar" over the site of injury. This process (fibrosis) leads to the construction of rigid fibrous tissue. In the embodiment of Figure 5, the bent leadless device 40 is fixed to the septal wall by filling the gap between the bent leadless device 40, which has a fixing helical body 30 wrapped around it, and / or by covering the bent leadless device 40 with such cell deposition. This fixing effect is more effective when the body of the leadless device 40 is bent toward the septum surface.

[0067] Optionally, an axially elongated X-ray marker 70 made of an X-ray detectable material may be provided on the housing of the leadless device 40 (e.g., attached or integrally formed) to indicate the bending direction of the leadless device 40 before it is released from the delivery catheter used to position the leadless device into the RV.

[0068] The axially extended X-ray marker 70 may be similarly provided in other embodiments to indicate the axial direction of the leadless device 40 after placement.

[0069] Furthermore, since the role of the X-ray marker can be similarly achieved by the section electrode pattern 60, the X-ray marker 70 may be omitted.

[0070] Figure 6 schematically shows a side cross-section of a leadless device 40 equipped with an expandable fixed spiral 30 having a radially varying thickness along the longitudinal direction, after the expandable fixed spiral has been inserted into the septum 24 according to the fourth embodiment.

[0071] As shown in Figure 6, the second subsection S2b of the extendable fixed helical body 30 may include helical turns 32, 33 having different cross-sectional widths in the radial direction R of the leadless device 40. In the example in Figure 6, the proximal portion of the second subsection S2b includes a first helical turn 33 with a larger radial width, while the distal portion of the second subsection S2b includes a second helical turn 32 with a smaller radial width, thereby achieving the desired mechanical properties along the extendable fixed helical body 30. For example, in this embodiment, the elongation rate of the proximal portion is smaller than that of the distal portion, and the axial length of the leadless device 40 can be shortened to reduce the space requirement within the RV. Further features include the puncture process being facilitated by the restraining effect provided by the thick cross-sectional width along the second subsection S2b, shortening the section so that it can be easily inserted into the septum. Yet another effect is that the spring effect of the second subsection S2b is used to constrict the RV cathode (C) with the tissue on the RV side. RV ) may be increased (or decreased) to maintain physical contact.

[0072] Other patterns of variable radial cross-sections of helical turns along the axial direction are also feasible to achieve different mechanical properties along the stretchable fixed helical body 30 (for example, by laser tube cutting using an original tube having multiple outer diameters along the axial length).

[0073] In the above embodiment, the housing of the leadless device 40 may be made of a plastic material such as polyether ether ketone (PEEK) to satisfy high biocompatibility and an extremely rigid mechanical structure. Alternatively, the housing of the leadless device 40 may be made of titanium (for example, to achieve X-ray transparency, weldability, desired mechanical and biological properties, etc.) and coated with an insulating coating such as parylene or ethylene tetrafluoroethylene (ETFE).

[0074] In summary, a pacing device (including, but not limited to, a leadless device) is described, which has an extensible portion that stretches when screwed into the tissue, thereby reducing the space required for insertion and allowing the pacing device to be positioned in a bent state to minimize unwanted mechanical interactions.

[0075] The present invention is illustrated and described in detail in the drawings and the above description, but these illustrations and descriptions are illustrative or illustrative and not limiting. The present invention is not limited to the disclosed embodiments of leadless pacing devices. The present invention can be applied to various types of pacing devices (e.g., bradycardia or tachycardia lead devices with multi-lumen, coaxial or concentric structures) and applications in the field of cardiac pacing or sensing systems to reduce the space required before and / or after insertion of a fixed helical body.

[0076] In the above embodiment, the fixed helical body may have an asymmetrical configuration with respect to its outer circumference and / or the cross-sectional shape of its turns, with respect to its major axis. For example, the width of the turns may be thinner on one side than on the other.

[0077] A suitable lead device design may have a multi-lumen, coaxial, or concentric structure, whether for tachycardia or bradycardia, and may include a central lumen for stylet passage. A coaxial lead, for example, has an internal conductor that extends along the lead length to a tip electrode (helical body) that is coiled and serves as the cathode, providing a central lumen for stylet passage during implantation.

[0078] Concentric bipolar leads address some of the disadvantages of coaxial leads in terms of bulkiness and rigidity of four-layer designs by employing new conductor and insulator technologies. A single coil extends along the entire length of the lead (which also has a central lumen for stylet insertion) and includes two parallel alternating conductors, one connected to the cathode and the other to the anode. Each conductor is individually coated with a bonding layer of, for example, ethylene tetrafluoroethylene (ETFE) fluoropolymer insulator to insulate it from one another even when entangled. A single two-component coil may be covered by a single outer insulating sheath.

[0079] Multi-lumen, coaxial, or concentric leads may optionally include a fixed, non-retractable helical body to minimize size. However, retractable helical bodies may also be used in connection with the embodiments described.

[0080] Furthermore, the proposed reed system may be configured to provide improved torque transmission, namely the ability to safely and accurately transmit torque to the helical body (e.g., full reed body torque) and stylet drive compatibility that facilitates operation (e.g., by push transmission). As an example, a concentric reed with a compatible screw-in stylet (screwdriver stylet) may be provided.

[0081] The proposed lead device, equipped with an extendable fixed helical body, can be adapted to or configured to adapt to IS1, IS4 (low voltage), or DF4 (high voltage) connectors.

[0082] Other modifications to the disclosed embodiments can be understood and achieved by those skilled in the art in carrying out the claimed invention by referring to the drawings, disclosures, and appended claims. The word “including” in the claims does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude plurals. The mere fact that certain measures are referenced in different dependent claims does not imply that combinations of these measures cannot be used to produce benefits. The above description details certain embodiments of the invention. However, no matter how detailed the above description may be, it will be understood that the invention can be carried out in many ways and is therefore not limited to the disclosed embodiments. It should be noted that the use of certain terms in describing certain features or aspects of the invention does not mean that the terms are redefined herein to the extent that they are limited to including certain characteristics of the features or aspects of the invention to which they relate.

Claims

1. The device includes a distal fixation helical body (30) for fixing the pacing device (40) to the patient's tissue. The fixed helical body (30) has a distal rigid section (S1) for puncturing and screwing the fixed helical body (30) into the patient's tissue, and an extendable section (S2) configured to extend in the axial direction of the fixed helical body (30) when the fixed helical body (30) is screwed into the patient's tissue. A pacing device (40) characterized in that the flexibility of the distal rigid section (S1) is lower than the flexibility of the proximal extendable section (S2).

2. The pacing device (40) according to claim 1, characterized in that the extendable section (S2) of the fixed helical body (30) is at least partially arranged around the housing of the pacing device (40).

3. The helical turn (32) of the extendable section (S2) is insulated by an insulating coating, and at least one helical turn (34) of the distal rigid section (S1) is a pacing electrode (C ＬＶ The pacing device (40) according to claim 1 or 2, characterized in that it is non-insulating in order to form a )

4. The fixed helical body (30) has at least two separate helical wire structures, each comprising separate helical turns (32, 36) that are staggered in the axial direction of the fixed helical body (30), the first of which comprises the distal rigid section (S1), and the second of which comprises at least one non-insulated helical turn (35) located proximal to the distal rigid section (S1), comprising the second pacing electrode (C ＲＶ The pacing device (40) according to any one of claims 1 to 3, characterized by forming a )

5. The pacing device (40) according to any one of claims 1 to 4, characterized in that the extendable section (S2) has a subsection (S2b) having predetermined bending properties such that when the fixed helical body (30) is screwed into the patient's tissue, the pacing device (40) is pressed toward the surface of the patient's tissue.

6. The pacing device (40) according to claim 5, characterized in that the predetermined bending characteristics are caused by a partial increase in the cross-sectional width (LCS) of the helical turn (32) of the subsection (S2b) in the axial direction of the fixed helical body (30).

7. The pacing device (40) according to claim 5 or 6, characterized in that the subsection has a helical turn (33) which changes the radial cross-sectional width of the fixed helical body (30).

8. The pacing device (40) according to any one of claims 1 to 7, characterized in that a pacing electrode (50) is provided at the distal end of the housing.

9. The pacing device (40) according to any one of claims 1 to 8, characterized in that an axially extended X-ray marker (70) is provided on the side of the housing of the pacing device (40).

10. The pacing device (40) according to any one of claims 1 to 9, characterized in that it is a leadless device for pacing bundled branches.

11. A method for manufacturing a fixing helical body (30) for fixing a pacing device (40) to a patient's tissue, A distal rigid section (S1) is formed for puncturing and screwing the fixing spiral body (30) into the patient's tissue. A method characterized by including the step of forming an extendable section (S2) configured to extend in the axial direction of the fixing helical body (30) when the fixing helical body (30) is screwed into the patient's tissue.

12. The method according to 11, further comprising the step of forming a subsection (S2b) having predetermined bending properties so as to press the pacing device (40) toward the surface of the patient's tissue when the fixed helical body (30) is screwed into the patient's tissue.

13. The method according to 12, characterized in that it includes a step of using a laser tube cutting process or heat treatment to obtain the predetermined bending characteristics.

14. A method for manufacturing a pacing device (40), comprising the steps of any one of claims 11 to 13, and further the step of arranging at least a portion of the extendable section (S2) of the fixed helical body (30) around the distal portion of the housing of the pacing device (40).

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