Multi-electrode leads containing elongated electrodes

Abstract

The present invention relates to a multi-electrode lead device, the multi-electrode lead including an inter-electrode section between a first distal electrode and a second proximal electrode. The inter-electrode section includes an elongated surface electrode for right bundle branch pacing, the elongated surface electrode having a reduced exposed area and at least one unexposed portion for increased current density. The elongated surface electrode is connected to a single pacing input terminal of a proximal lead connector. The reduced exposed area of ​​the elongated surface electrode increases current density, thereby reducing energy consumption and expanding the right bundle branch pacing area in various anatomical structures.

Description

[Technical Field]

[0001] The present invention relates to the field of lead devices (e.g., electrode catheters) for cardiac pacing systems, such as, but not limited to, left bundle branch pacing (LBBP), cardiac resynchronization, or tachycardia ("Tachi") systems. [Background technology]

[0002] Different electrical activation sequences in cardiac pacing can have different consequences on the mechanical pumping efficiency of the stimulated heart. Optimal pumping efficiency requires rapid and uniform contraction of the ventricles.

[0003] Traditional pacing sites, such as the right ventricular apex (RVA), may provide stable lead positioning at low displacement rates but are less effective at optimizing left ventricular (LV) contraction (which accounts for approximately 80% of the cardiac mass). Chronic RVA pacing can adversely affect left ventricular function by inducing iatrogenic left bundle branch block (LBBB), which can have profound effects on left ventricular hemodynamics. This observation led to a reevaluation of traditional approaches and the investigation of alternative pacing sites to achieve more physiologic ventricular activation patterns and avoid adverse effects.

[0004] LBBP has emerged as an alternative method of physiological pacing to achieve LV electrical synchrony, particularly in patients with infranodal atrioventricular block and / or LBBB. The proximal LBBB passes through the LV septum and fan-out, providing a wider pacing target compared with the His bundle. Techniques for LBBP using the transseptal approach (i.e., pacing the LV from the RV) have been developed. LBBP has been reported to have a low pacing threshold and large R waves, and because it targets the distal conduction system, there is a theoretically low risk of distal conduction block.

[0005] After determining the initial placement site of the LBBP on the right surface of the ventricular septum, the pacing lead (i.e., the helical fixation element or electrode at the lead tip) is screwed into the left ventricular (LV) septum, for example, by puncturing the tissue with the distal tip of the helical fixation element (fixation helix). The depth of the LBBP lead into the LV septum can be determined by observing changes in the V1 lead notch, sheath angiography, the fulcrum sign, and / or impedance monitoring. The pacing lead is slowly advanced with torque to the determined depth (e.g., approximately 6–8 mm) while avoiding septal perforation. Finally, LBB capture is confirmed based on acceptable pacing parameters. This confirmation can be based on at least one of the following: the morphology of the RBBB pattern after pacing, recording of LBB potentials, LVAT stimulation peaks that shorten rapidly with increasing output or remain shortest and constant at low and high outputs, selective and non-selective LBBP, recording of retrograde His potentials or orthodromic LBB potentials during pacing.

[0006] Common features of the implantation or placement process include transvenous access, transseptal placement of the pacing lead into the left ventricular (LV) septal subendocardium in the LBB region, and confirmation of LBB capture.

[0007] However, due to the variability of patient anatomy, there may be some variability in the interventricular thickness of the left ventricular (LV) septum, which can vary from approximately 10 mm to approximately 20 mm. In addition to the uncertainty of overall septal thickness, the location of LBB conduction fibers deep within the septal tissue also varies between patients, typically located near the left ventricular border of the septum, approximately 1–5 mm away. To ensure successful left ventricular capture at the lowest capture threshold, the distal electrode of the lead may need to be deployed as close as possible to the LBB fibers while avoiding the risk of penetrating the septum and entering the left ventricular cavity.

[0008] Furthermore, in the case of combined LBB and RBB pacing, control of both LBB and RBB must be achieved by properly positioned LV and RV cathodes, respectively. The delivered electrical pulses must be designed to have low energy consumption. From a geometrical point of view, this means that at least a portion of the RV cathode must be as close as possible to the RBB fibers, and at least a portion of the LV cathode must be as close as possible to the LBB fibers. Summary of the Invention

[0009] The object of the present invention is to provide a lead device that is configured to be usable while ensuring low energy consumption regardless of differences in the anatomical structure (particularly the thickness) of the septum of a patient or device recipient (hereinafter referred to as "various anatomical structures").

[0010] This object is achieved by a lead device as claimed in claim 1.

[0011] The proposed lead device includes an inter-electrode portion between a first distal electrode and a second proximal electrode, the inter-electrode portion including an elongated surface electrode (i.e., having a long longitudinal length) for right bundle branch pacing, the elongated surface electrode having a reduced exposed area and at least one unexposed portion to expand the right bundle branch pacing area with increased current density, and the elongated surface electrode is connected to only one (i.e., a single) pacing input terminal of the proximal lead connector.

[0012] In a bipolar lead containing a first and second electrode (e.g., an anode and at least one cathode), one electrical channel conducts electrical pacing pulses toward the lead tip and the distal first electrode (e.g., the cathode), while the other channel completes the circuit back to the pacemaker via the proximal second electrode (e.g., the anode). Myocardial capture requires a minimum local current density (i.e., the ratio of pacing current (electrons) to pacing area) at the contact area (exposed area) of the first electrode (cathode). A smaller exposed area increases current density and also increases resistance, thereby reducing current and extending battery life.

[0013] It should be noted that the present invention can also be used in conjunction with a unipolar lead, in which case the second electrode (e.g., the anode) is located on or corresponds to the housing of a pacing device (e.g., an implantable pacemaker), and the inter-electrode portion can extend from the first electrode to the pacing device. In this case, a connector (e.g., an IS1 connector) including a single connecting electrode or terminal can be used at the proximal end of the lead device.

[0014] Thus, elongated surface electrodes with small exposed areas are designed for low power consumption by achieving increased current density, thereby expanding the right bundle branch pacing area. From a geometric perspective, this means that in various septal anatomies, at least a portion of the elongated right ventricular (RV) cathode can be placed near the RBB fibers, while at least a portion of the left ventricular (LV) cathode can be placed near the LBB fibers. Thus, multiple lead models for different anatomies and / or pre-operative testing to measure septal wall thickness are not required.

[0015] The substrate or body of the elongated surface electrode (i.e., the combination of the pacing surface and insulating surface) can be constructed as a single physical component, thereby maintaining a lead design with a desired stiffness gradient in the region that is inserted into the septum. Stiffness gradients can lead to changes in the bending of the lead tip, increasing the risk of breakage. Thus, multiple pacing surfaces can be disposed (e.g., implanted) on the elongated surface electrode, all electrically interconnected and connected to a single terminal or electrode of a connector at the proximal end of the lead device. Because the pacing surface can be constructed as a single mechanical element, it can be configured to continuously provide the desired stiffness to protect the lead tip. This avoids the (sharp) stiffness gradients that would occur in the presence of multiple individual electrodes, which could potentially damage the lead tip during the puncture process. This also allows the total pacing surface of the elongated surface electrode to be spread over a longer axial distance, increasing the likelihood that a portion of the elongated surface electrode will be as close as possible to the tissue region to be stimulated (e.g., RBB) in various anatomical structures (e.g., septal thickness) and achieving the desired cumulative reduced pacing surface (e.g., 2-8 mm). 2 ) and / or by maintaining a constant electrical contact. The pacing surface may be continuous or discontinuous along the axial length of the elongate surface electrode and may thus be composed of one or more separate pacing surface regions that may be electrically connected to one another.

[0016] According to a first option, the non-exposed portion may include an electrically insulating cover, which serves to reduce the exposed area of ​​the elongated surface electrode, thereby providing an elongated electrode that is more compliant with various anatomical structures, while increasing current density and reducing energy / battery consumption.

[0017] According to a second option, the electrically insulating cover can be arranged in a recess in the elongated surface electrode, such that by embedding the electrically insulating cover in the recess, an elongated surface electrode with a reduced exposed surface area can be produced in a reliable and robust manner.

[0018] According to a third option, the elongated surface electrode may comprise a spiral electrode pattern wound around the lead body of the lead device. This option provides a simple way to reduce the size of the exposed area by simply placing the spiral electrode pattern around the lead body of the lead device in the inter-electrode portions.

[0019] According to a fourth option, the spiral electrode pattern may be disposed around or at least partially embedded within an insulating coating on the lead body, which ensures that the uncovered portions of the lead device body are insulated and therefore not exposed.

[0020] According to a fifth option, the non-exposed portion may include at least one cut-out portion that is not covered by the electrically insulating cover. In this way, the elongated surface electrode may be manufactured as a single cylindrical element, and the exposed area may be reduced by simply cutting out the desired portion (e.g., by laser ablation), resulting in a higher current density delivered by the electrode with a reduced exposed surface area, thereby reducing energy / battery consumption.

[0021] According to a sixth option, the cutouts may be distributed over the surface of the elongated surface electrode, which ensures that the current density is more evenly distributed over the entire surface of the elongated surface electrode.

[0022] According to a seventh option, which can be combined with any one of the first to sixth options, the distal first electrode can be formed with a fixation helix, which allows the first electrode to be used to screw the lead tip into the tissue of the septum.

[0023] According to an eighth option, which can be combined with any one of the first to seventh options, the second proximal electrode can be an anode, allowing all electrodes to be located at the lead tip and easily connected to a proximal connector (e.g., a standard IS4 connector).

[0024] According to a ninth option, which can be combined with the seventh or eighth option, the ratio of the first outer diameter of the fixation helix to the second outer diameter at the distal end of the inter-electrode portion can be set between 0.8 and 1, the first outer diameter can be set between 1 and 1.8 mm, the length of the elongated surface electrode can be set between 7 and 11 mm, and the length of the fixation helix can be set between 1.5 and 5 mm. These dimensions facilitate the process of screwing the lead tip into tissue.

[0025] According to a tenth option, which can be combined with any one of the first to ninth options, the inter-electrode portion can have a conical shape, which reduces resistance when the lead tip enters tissue during the screwing process.

[0026] According to an eleventh option, which can be combined with any one of the first to tenth options, the body of the lead device can have a co-radial structure, which allows for a less bulky and less stiff lead design.

[0027] According to a twelfth option, which can be combined with any one of the first to eleventh options, the axial distance between the distal end of the fixation helix and the distal end of the elongated surface electrode can be in the range of 7 mm to 12 mm, the axial length of the elongated surface electrode can be in the range of 7 mm to 11 mm, and the axial distance between the distal end of the elongated surface electrode and the distal end of the proximal second electrode can be in the range of 10 mm to 20 mm.

[0028] According to a thirteenth option, which can be combined with any one of the first to twelfth options, the elongated surface electrode has a resulting limited active electrode surface size of 2 to 8 mm.2 This allows for good electrical performance while maintaining current consumption and thus extending the life of the device.

[0029] It is further understood that a preferred embodiment of the invention may also be any combination of the dependent claims or the above embodiments with the respective independent claim.

[0030] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. [Brief explanation of the drawings]

[0031] [Figure 1] 1 shows a schematic representation of a heart with a lead device placed for ventricular transseptal LBB pacing. [Figure 2] Schematically shows a side view of a lead device according to a first embodiment, including a first cathode formed by a fixed helix and a second cathode formed by an elongated electrode structure having an outer coating to limit exposure. [Figure 3] 1 shows a schematic cross-sectional view of an elongated electrode structure of a first embodiment; [Figure 4] FIG. 1 shows a schematic side view of a lead device according to a second embodiment, including a first cathode formed by a fixed helix and a second cathode formed by an elongated spiral electrode structure wrapped around the body of the lead device to limit exposure. [Figure 5] 1 shows a schematic cross-sectional view of an elongated spiral electrode structure of a second embodiment. [Figure 6] FIG. 10 shows a schematic side view of a lead device according to a third embodiment, including a first cathode formed by a fixed helix and a second cathode formed by an elongated electrode structure having a notched portion to limit exposure. DETAILED DESCRIPTION OF THE INVENTION

[0032] Various embodiments of the present invention are described based on an improved lead device (e.g., electrode catheter) that includes a fixation helix. The present invention is particularly advantageous in the context of transseptal pacing, such as LBBP, but is not limited thereto and may be used in combination with other pacing types and / or sites in other applications requiring placement of a lead device within body tissue.

[0033] It should be noted that throughout this disclosure, the accompanying drawings only show elements, parts, components, and / or devices related to the proposed lead device and deployment procedure. Other elements, parts, components, and / or devices are omitted for the sake of brevity. Furthermore, components designated with the same reference numeral or number are intended to have the same or at least similar functionality, and therefore, their functionality will not be described again below.

[0034] Additionally, throughout this disclosure, "proximal" and "distal" are terms used to refer to the distance from the operating end (reference point) of the lead device where the physician or other user controls the screwing process, with proximal being closer to the operating end and distal being further away from the operating end.

[0035] FIG. 1 shows a schematic of a heart with a lead device 200 inserted, with the pacing lead tip 20 positioned for ventricular septal LBBP. This allows pacing of the RV from the LV via a ventricular septal approach as a guide for catheter delivery. The placement of the pacing lead tip 20 can be performed based on the procedures described above. LBBP can be defined as capture of the LBB (i.e., the left bundle trunk or its proximal bundles / fibers), typically capturing the septal myocardium at low power (e.g., <1.0 V / 0.4 ms).

[0036] In normal cardiac function, the heartbeat is initiated within the heart by the sinoatrial node (SAN), located at the top of the right atrium (RA), which determines the heart's contraction rate. The SAN sends out electrical impulses that are transmitted through the muscular walls of both atria. These impulses cause atrial contraction. The impulses then travel to another node within the heart, the atrioventricular node (AVN), located at the bottom of the right atrium (RA). When the impulse from the sinoatrial node (SAN) reaches the atrioventricular node (AVN), it is transmitted to conduction fibers that travel down the central wall of the heart. The impulse then branches and travels up the left ventricle (LV) and right ventricle (RV), which contract simultaneously (ventricular systole).

[0037] Important elements of the cardiac conduction system reside within the septum 24. The bundle of His courses through the subendocardium for approximately 1 cm along the right side of the septum 24 and branches into the LBB and RBB. The RBB courses along the right side of the septum 24, and the LBB crosses to the left side, where it branches anteriorly and posteriorly.

[0038] Under normal conditions, cardiac rhythm is controlled by excitation from the sinoatrial node (SAN). Abnormal sinus rhythm leads to arrhythmia, which refers to abnormalities in the rate, rhythm, site of origin, and conduction of the heart's electrical impulses. When specific conduction fibers within the ventricles are damaged, the repolarization wave must then travel along slower intermuscular pathways to reach the ventricles. Typical disorders associated with pathologies involving different conduction bundle branches include LBBB and RBBB. An electrocardiogram (ECG) obtained from an implanted lead device can be used to measure and record the heart's electrical activity, thus providing important information about cardiac function. The ECG has been used as a standard diagnostic tool for analyzing arrhythmias.

[0039] In embodiments, the lead tip of a pacing or tachycardia lead is designed to avoid the risk of septal perforation. These lead tips may also be equipped with a soft tip (e.g., made of silicone) to increase the stopping surface. That is, when the helical fixation element or electrode (hereinafter referred to as the "helix") engages (e.g., threads) with (cardiac) tissue, the tissue presses against the soft tip, preventing the helix from rotating and further advancing within the tissue. The length of the helix may be limited to an effective length, e.g., about 2 mm. The lead and / or helix should be designed to optimize the energy / force required for penetration and allow for a well-controlled and safe advancement without increasing the complexity of the lead.

[0040] Additionally, according to embodiments, the body of the lead device may be configured to improve lubricity with a guide catheter used to navigate the lead device (e.g., through a blood vessel) to a target region. This may be achieved, for example, by using a reduced diameter polyurethane (PU) material to reduce the effort required to advance the lead body through the guide catheter and the lead tip 20 through the septum 24.

[0041] Suitable lead device designs according to embodiments, for either tachycardia or bradycardia leads, can have a multi-lumen, coaxial, coradial configuration, with a central lumen for passage of a stylet. Coaxial leads have an inner conductor that runs along the length of the lead to a cathode, which is a tip electrode (helix) arranged in a coil configuration that provides a central lumen for passage of, for example, a stylet during implantation.

[0042] Co-radial bipolar leads address some of the drawbacks of coaxial leads, such as the bulkiness and stiffness of their four-layer design, through new conductor and insulator technology. In this technology, a single coil extends the entire length of the lead (also containing a central lumen to allow for stylet insertion) and consists of two parallel, alternating conductor strands, one of which is connected to the cathode and the other to the anode. Each conductor strand can be individually coated with an adhesive layer, such as ethylene tetrafluoroethylene (ETFE) fluoropolymer insulation, which serves to insulate the strands from each other despite their intertwined nature. The single, two-element coil may be surrounded by a single outer insulating cover.

[0043] Multilumen, coaxial, or coradial leads may optionally include a fixed, non-telescopic helix to minimize size, although telescoping helices may also be used in conjunction with the described embodiments.

[0044] Additionally, the proposed multi-electrode lead device according to embodiments can be configured to provide improved torque transmission, i.e., the ability to safely and accurately transmit torque to the helix (e.g., torque across the entire lead body), and stylet-driven compatibility (e.g., via push-to-drive) for ease of handling. In one example, a core radial lead can be provided that includes a compatible screw-in stylet (screw-driven stylet).

[0045] The following embodiments of the proposed multi-electrode lead device are configured to be usable in multiple, diverse anatomies with different septal thicknesses and / or RBB and / or LBB fiber structures and to comply with applicable standards (e.g., International Standard IS4, which allows for up to four independent wires). This is achieved by providing an elongated pacing electrode structure with increased longitudinal width and reduced exposed pacing surface area to reduce battery consumption. More specifically, in addition to the first cathode formed by a helix, a second cathode can be formed by a longitudinally elongated electrode structure with reduced exposed surface area, allowing for increased current density. The embodiments address various options for reducing the exposed surface area of ​​the elongated electrode structure, such as partial coverage with an insulating coating, a surface-reduced electrode pattern, and / or one or more cutouts in the conductive electrode surface.

[0046] The elongated second cathode allows for more flexible two-sided pacing (e.g., for simultaneous LBB and RBB pacing) for various anatomical structures. This allows the multi-electrode lead to accommodate various septal wall thicknesses. To reach effective pacing thresholds, the exposed conductive surface of the elongated cathode must physically contact tissue, exposing a limited pacing surface.

[0047] The two pacing electrodes can be electrically independent by using at least one of different timing, different thresholds, and different impedances, and the like.

[0048] FIG. 2 shows a schematic side view of a multi-electrode lead device 200 including a lead tip according to a first embodiment, including a first cathode (C LV ) is formed by a fixed helix 30 and the second cathode (C RV1 , C RV2 ) are formed by elongated electrode structures 208a-208c that include an outer electrically insulating cover 208c to limit exposure.

[0049] The lead tip of the lead device 200 punctures cardiac tissue (septal tissue) with the distal tip of the fixation helix 30, thereby screwing the fixation helix 30, having an effective length a, into the cardiac tissue. The lead device 200 can be used to stimulate the LBB and RBB. The lead device 200 can include an elongated body extending between a proximal end including a connector 220 configured to connect to, for example, an implantable pulse generator, and a distal end located at the fixation helix 30. The elongated body can also include a lumen extending between the proximal and distal ends.

[0050] In at least some of the following embodiments, with regard to the design of the distal end (distality) of the lead device 200, the ratio between the outer diameter of the helix 30 and the outer diameter of the lead tip housing may be greater than 70%, ideally 100%, and an equal profile distality may be provided to avoid an anterior stop surface for better insertion.

[0051] Additionally, the helix 30 may be made of a rigid material to avoid deformation of the helix 30 during screwing, but a fixed helix 30 (i.e., a lock between the helix 30 and the lead body) can simplify handling (i.e., no parasite tools are required for the retractable system).

[0052] Additionally, design flexibility can be provided by adapting the distance b between the fixation helix 30 and the proximal elongated second cathode for bilateral pacing and / or the longitudinal length c of the elongated second cathode to the desired range of septal thicknesses for different individuals.

[0053] The distal design of the lead device 200 can be further configured to allow the lead tip to be advanced smoothly and predictably into the septum until the helix (cathode) 30 reaches the desired location in the left ventricle (LV), i.e., near the LBB without completely perforating the septum, so that the helix 30 does not protrude into the left ventricle (LV).

[0054] Additionally, the design of the lead device 200 can be configured to minimize the energy / torque required to perform septal puncture. This can be accomplished by providing a specialized distal tapered lead tip (not shown) with a cone-shaped interelectrode section having an axial or longitudinal length e between the proximal end of the helix 30 and the distal end of the proximal anode (A) 206. The distal end of the anode 206 is located a longitudinal distance d from the distal end of the elongated second cathode.

[0055] In some cases, at least a proximal portion of fixation helix 30 may be insulated, while at least one turn at the distal end of fixation helix 30 may be uninsulated. One or more turns of fixation helix 30 (e.g., inside the lumen of the elongate body) may be covered with a dielectric or other insulating material. Removing the proximal portion or turn of fixation helix 30 may minimize impedance interference that may result from the spacing between the proximal electrode (not shown) and fixation helix 30.

[0056] The fixation helix 30 can be attached (e.g., welded) to a driver (not shown). The driver may include a surrounding coil or other non-planar, regular or irregular surface structure (not shown) to ensure good adhesion between the driver and the surrounding material of the lead body between the proximal end of the fixation helix 30 and the distal end of the anode 206, resulting in a simple, rigid, and durable lead tip structure with fewer parts and improved long-term reliability. The driver (not shown) is fixedly supported on the lead body and mechanically and electrically connected to a matching threaded stylet adapter (not shown) for insertion of the mating end (engagement portion) of a separate threaded stylet, which rotates the fixation helix 30 via the driver, thereby providing a screw-driving function. The electrical connection between the fixation helix 30 and the threaded stylet allows the electrical signals sensed by the fixation helix 30 in the target area to be sent to a signal analyzer via the threaded stylet, allowing for one-step operation by monitoring whether the fixation helix 30 is properly positioned without cutting during the threading operation.

[0057] The conical shape of the lead tip can be determined based on dimensional parameters, for example, the outer diameter Da of the proximal anode 206, the outer diameter DI of the distal section of the lead tip, the outer diameter Dh of the fixation helix 30, the length a of the fixation helix 30, and the overall length Lt (e.g., e+d+b) of the lead tip, including the fixation helix 30 and the tapered portion of the lead body (e.g., surrounding the driver) between the fixation helix 30 and the proximal anode 206.

[0058] In an example, the ratio Dh / DI can be set between 0.8 and 1, while Dh can be set between 1 and 1.55 mm (preferably 1.40 mm). Da can be set between 1.25 mm and 1.94 mm (preferably 1.66 mm), the length a of the fixed helix 30 can be set between 2 mm and 5 mm, the difference ba can be set between 5 mm and 7 mm, the longitudinal length c of the elongated second cathode can be set between 7 mm and 11 mm, the distance d can be set between 10 mm and 20 mm, and the longitudinal length e of the anode 206 can be set between 5 mm and 10 mm.

[0059] The particular cone shape proposed in the above size range allows a lead tip including a fixed helix 30 to penetrate tissue in a target area in a controlled and smooth manner, providing a cone profile that minimizes the energy required to effect the penetration.

[0060] In the specific example shown in FIG. 2 and subsequently in FIGS. 4 and 6, the connector 220 at the proximal end of the lead device 200 includes four independent connector electrodes (terminals), including three circumferential connector electrodes 202 and one axial connector electrode 204. This connector design is compatible with a standard IS4 connector and is configured to provide connection for up to four electrical lines or wires of the lead device 200. In the specific example, three of the four connector electrodes are used to connect to the anode 206, the elongated second cathode, and the first cathode of the fixation helix 30. The axial connector electrode 204 is connected via a first line to the fixation helix 30 (cathode C for left ventricular pacing (LV)). LV ) to connect the first connector electrode (CC LV ) 204. The first electrode (CC RV ) is connected via a second line to a second elongated cathode (C for right ventricular (RV) pacing) RV1 , C RV2 Finally, the second electrode (CA) of the circumferential connector electrode 202 connects to the anode (A) via a third line.

[0061] The anode 206 has a large surface area (e.g., 40 mm 2 ) can be used as a sensing electrode and can be configured as a single electrode or two electrodes.

[0062] 2, the elongated second cathode is configured as a single long, optionally flexible cathode and is connected via a single internal connection to a wire or line that connects to the most proximal of the three circumferential connector electrodes 202 of the connector 220. This allows for a simple and robust design.

[0063] The elongated second cathode includes a first ring-shaped exposed region 208a at a proximal end of the elongated second cathode and a second ring-shaped exposed region 208b at a distal end of the elongated second cathode. In one example, the total exposed area of ​​the two ring-shaped exposed regions 208a and 208b is 4 mm 2~8mm 2 To reduce the overall exposed area of ​​the elongated second cathode, a central portion of the elongated second cathode is covered with an electrically insulating cover 208c.

[0064] FIG. 3 shows a cross-sectional view of the elongated electrode structure of the first embodiment.

[0065] The elongated second cathode is fabricated as a single mechanical part from a cylindrical conductive material. The elongated second cathode has a recessed insulated central section, into which an electrically insulating cover 208c is embedded by depositing an insulating material (e.g., a parylene coating or other insulating coating). This results in two exposed cathode areas (cathodes) 208a and 208b, while both cathodes are connected to the same internal wire, simplifying the internal design and providing a robust electrode structure. Reducing the exposed area increases current density during pacing, thereby reducing energy / battery consumption.

[0066] FIG. 4 is a schematic side view of a multi-electrode lead device according to a second embodiment, showing a first cathode (C LV ) is formed by a fixed helix 30 and the second cathode (C RV ) 209 is formed by an elongated spiral electrode structure having a longitudinal length c that is wrapped around the body of the lead device 200 to limit exposure.

[0067] The elongated second cathode 209 is connected to the most proximal of the three circumferential connector electrodes 202 via a single internal wire or line. The helical electrode structure of the elongated second cathode increases the longitudinal length c to better accommodate different septal anatomies, while reducing the exposed area and energy / battery consumption. It can be patterned as a single coil or with multiple coils connected together.

[0068] FIG. 5 shows a cross-sectional view of an elongated spiral electrode structure of a second embodiment.

[0069] The lead body 211 of the lead device 200 may be coated with an insulating coating 210 (e.g., silicone or polyurethane fill) to reduce the exposed surface (pacing surface), and a helical pacing coil (or other pattern) 209 is disposed around or partially embedded in the insulating coating 210. This results in a single, long, flexible secondary cathode that can be connected to a wire or line that connects to the connector 220 via a single internal connection, resulting in a simple and robust design. In one example, the total exposed surface of the elongated helical secondary cathode 209 is 4-8 mm. 2 and the total length ranges from 2 to 10 mm.

[0070] FIG. 6 shows a side view of a multi-electrode lead device according to a third embodiment, in which a first cathode is formed by a fixed helix 30 and an elongated second cathode 212 is formed by an elongated electrode structure having a cutout portion 213 to limit / reduce exposure.

[0071] Again, the elongated second cathode 212 can be fabricated as a single mechanical part from a cylindrical conductive material and includes a cutout portion 213 that can be open (no conductive material) or filled with insulating material to reduce the total exposed surface area, thereby increasing current density and reducing energy / battery consumption.

[0072] The cutout portions may have an elongated rectangular shape and may be substantially equally spaced around the circumference of the elongated second cathode 212. Alternatively, other shapes (e.g., oval, circular, slit-like) may be provided, and / or multiple cutout portions may be provided in the axial direction. Further alternatively, smaller cutout portions of the same or different shapes may be scattered across the surface of the elongated second cathode 212. Still alternatively, one or more cutout portions may be arranged to extend circumferentially around the elongated second cathode 212, covering most or different angular portions of the circumference of the elongated second cathode 212.

[0073] This allows for a reduction in the total exposed area of ​​the elongated second cathode 212, while also simplifying the internal design and providing a robust electrode structure by connecting the elongated second cathode 212 to a single internal wire or line. Reducing the exposed area increases the current density during pacing, thereby reducing energy / battery consumption.

[0074] As an example applicable to all of the above embodiments, the elongated second cathode may be 2 to 8 mm 2 The electrode surface can be configured to remain active on a limited size range.

[0075] The electrode pattern of the elongated surface electrode can be created by selective insulating coating (e.g., parylene coating, which provides high insulation and good biocompatibility), for example, by mechanically masking the surface of the limited pacing surface to be left, and / or by selective laser ablation (by numerical control) of a fully coated electrode surface (locally removing the insulating coating), and / or by adding surface material by laser texturing.

[0076] In summary, we have described a multi-electrode lead device that includes an inter-electrode section between a first distal electrode and a second proximal electrode. The inter-electrode section includes an elongated surface electrode for right bundle branch pacing, which has a small exposed area and at least one unexposed section to enhance current density, and which is connected to a single pacing input terminal of a proximal lead connector. The small exposed area of ​​the elongated surface electrode enhances current density, reducing energy consumption and expanding the right bundle branch pacing area in various anatomies.

[0077] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are by way of example or illustration only and are not intended to be limiting. The invention is not limited to the disclosed embodiments. The invention is applicable to various types of lead devices, such as bradycardia or tachycardia lead devices of multi-lumen, coaxial, or coradial configurations, and is also applicable to applications in the field of cardiac pacing or sensing systems.

[0078] The proposed multi-electrode lead device 200 with an elongated electrode structure can be configured to fit or be adaptable to an IS1, IS4 (low voltage), or DF4 (high voltage) connector. The device can be used in combination with a leadless pacemaker that can deliver synchronous pacing pulses to both ventricles, with the elongated second cathode contacting the right ventricular (RV) septal branch and the first cathode (helix) passing through the septum to the left ventricular septum (LBB). This eliminates the need for additional hardware.

[0079] Other variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The above description details particular embodiments of the invention. However, no matter how detailed the foregoing description appears in the text, it will be understood that the invention can be embodied in various ways and is therefore not limited to the disclosed embodiments. It should be noted that the use of certain terms in describing particular features or aspects of the invention does not imply that these terms be redefined herein to include the specific characteristics of the feature or aspect of the invention to which they relate.

Claims

1. A lead device (200) for left bundle branch pacing and / or right bundle branch pacing, the lead device (200) comprising: a distal first electrode (30) adapted to be inserted into the septum of the heart by puncture and used for left bundle branch pacing; a second proximal electrode (206); an inter-electrode portion between the distal first electrode (30) and the proximal second electrode (206); the inter-electrode portion includes an elongated surface electrode (208a-c; 209; 212) for right bundle branch pacing, the elongated surface electrode (208a-c; 209; 212) having a reduced exposed area (208a, 208b) and at least one unexposed portion (208c; 213); the elongated surface electrodes (208a-c; 209; 212) are connected to only one pacing input terminal of the proximal lead connector (220); A lead device (200).

2. The lead device (200) of claim 1, wherein the unexposed portion includes an electrically insulating cover (208c).

3. The lead device (200) of claim 2, wherein the electrically insulating cover (208c) is disposed in a recess in the elongated surface electrode (208a-c).

4. 10. The lead device (200) of claim 1, wherein the elongated surface electrode comprises a spiral electrode pattern (209) wrapped around a lead body (211) of the lead device (200).

5. 5. The lead device (200) of claim 4, wherein the spiral electrode pattern (209) is disposed around or at least partially embedded in an insulating coating (210) of the lead body (211).

6. The lead device (200) of claim 1, wherein the unexposed portion includes at least one notched portion (213).

7. 7. The lead device (200) of claim 6, wherein a plurality of said cutout portions (213) are distributed on a surface of said elongated surface electrode (212).

8. The lead device (200) of any one of claims 1 to 7, wherein the distal first electrode is formed by a fixation helix (30).

9. The lead device (200) of any one of claims 1 to 8, wherein the second proximal electrode is an anode (206).

10. 9. The lead device of claim 8, wherein a ratio of a first outer diameter of the fixation helix to a second outer diameter at a distal end of the inter-electrode portion is between 0.8 and 1, the first outer diameter is between 1 and 1.8 mm, the length of the elongated surface electrode is between 7 and 11 mm, and the length of the fixation helix is ​​between 1.5 and 5 mm.

11. The lead device (200) of any one of claims 1 to 10, wherein the inter-electrode portion has a conical shape.

12. The lead device (200) of any one of claims 1 to 11, wherein the body (211) of the lead device (200) has a co-radial structure.

13. 13. The lead device (200) of claim 1, wherein the axial distance between the distal end of the fixation helix (30) and the distal end of the elongated surface electrode (208a-c; 209; 212) is in the range of 7-12 mm, the axial length of the elongated surface electrode (208a-c; 209; 212) is in the range of 7-11 mm, and the axial distance between the distal end of the elongated surface electrode (208a-c; 209; 212) and the distal end of the proximal second electrode (206) is in the range of 10-20 mm.

14. The elongated surface electrodes (208a-c, 209, 212) have a resulting limited active electrode surface size of 2-8 mm ２ The lead device (200) of any one of claims 1 to 13, configured to be in the range of

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