Threaded stylet for improving torque transmission in lead systems for cardiac stimulation - Patents.com

Abstract

The present invention relates to a threaded stylet for improving torque transfer from a physician's hand to the lead tip (e.g., helix) of a lead device. The lead tip is provided for ease of manipulation, and the threaded driver function of the threaded stylet is provided for improving torque transfer to the lead tip of the lead device for better control of the puncture process. The threaded stylet is directly engagable with the lead tip of the lead device, thereby achieving direct and efficient torque transfer to the helix fixed to the lead tip.

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 systems. [Background technology]

[0002] In the present disclosure, the following terms and their abbreviations may be used: electrocardiogram (ECG), left ventricle (LV), right ventricle (RV), left atrium (LA), right atrium (RA), right ventricular apex (RVA), His bundle pacing (HBP), left anterior oblique (LAO), right anterior oblique (RAO), left bundle branch (LBB), right bundle branch (RBB), left bundle branch pacing (LBBP), left bundle branch block (LBBB), left ventricular activation time (LVAT), right bundle branch block (RBBB), interventricular septum (VS), sinoatrial node (SAN), atrioventricular node (AVN), interventricular septum (IVS), right ventricular outflow tract (RVOT) pacing, direct His bundle pacing (DHBP), parahisian pacing (PHP).

[0003] Different electrical activation sequences in cardiac pacing can result in different mechanical pumping efficiencies in the stimulated heart. Optimal pumping efficiency requires rapid and uniform contractions of the ventricles.

[0004] Although traditional pacing sites such as the RVA provide stable lead positions with low displacement rates, they are less effective at optimizing LV contraction (which accounts for approximately 80% of the cardiac mass). Chronic right ventricular apical pacing can adversely affect left ventricular function by inducing ectopic left bundle branch block, which can have profound effects on left ventricular hemodynamics. This observation prompted a reevaluation of traditional approaches and the exploration of alternative pacing sites to avoid adverse effects and achieve more physiologic ventricular activation patterns; RVOT pacing, DHBP, PHP, and dual-site (RVA + RVOT) pacing have been tried.

[0005] LBBP has emerged as an alternative method for physiological pacing to achieve LV electrical synchronization, particularly in patients with subnodal atrioventricular block and / or LBBB. Because the proximal LBBB fans out through the LV septum, it creates a broader target for pacing compared to the His bundle. Techniques for LBBP have been developed using a transventricular approach (i.e., pacing the LV from the RV). LBBP has been reported to provide low pacing thresholds and large R waves, and because the distal conduction system is targeted, it carries a low theoretical risk of developing distal conduction block.

[0006] However, challenges remain in minimizing the effects of the pacing device through the septum (e.g., permanent arterial damage), miniaturizing and controlling the puncture process in the septum, and ensuring the long-term reliability of the pacing device, which is subject to the constraints of septal contraction. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide an electrode catheter system that addresses the above-mentioned problems encountered in connection with LBBP or other pacing approaches. [Means for solving the problem]

[0008] This object is achieved by a threaded stylet according to claim 1, a lead system according to claim 9 and a method according to claim 10.

[0009] According to a first aspect, a threaded stylet is configured to be insertable into a lead body of a lead device and has a coupling end configured to be engageable with a driver of the lead tip to transmit torque to the lead tip of the lead device.

[0010] According to a second aspect, a lead system includes the threaded stylet of the first aspect and a lead device having a lead tip provided with a driver configured to engage with the coupling end of the threaded stylet when the threaded stylet is inserted.

[0011] According to a third aspect, there is provided a method of transmitting torque to a lead tip of a lead device positioned in a target region of a human or animal body, the method comprising: inserting the threaded stylet into the lead device until the mating end of the threaded stylet engages a driver at the lead tip; a control handle fixed to the threaded stylet at a connector end opposite the coupling end is pushed in, and a connecting force is generated between the coupling end of the threaded stylet and the driver by elastically stretching a lead body of the lead device; locking the operating handle to the lead body using a locking element on the operating handle to maintain the connection force; The threaded stylet is rotated to transmit torque to the lead tip through the driver.

[0012] This allows for improved manipulation of the lead system and torque transfer to the lead tip of the lead device by coupling the threaded stylet with the lead device for better control of the puncture process. The threaded stylet is directly engagable with the lead tip of the lead device, allowing for direct and efficient torque transfer to the helix secured to the lead tip and improved manipulation by the physician.

[0013] According to a first option of any of the first through third aspects, the threaded stylet further comprises a conical and / or reduced diameter portion at the coupling end to enhance flexibility, thereby facilitating insertion of the threaded stylet into a lead device, even around curves.

[0014] According to a second option of any of the first to third aspects, the threaded stylet is made from stainless steel or nitinol, which provides a threaded stylet that is both highly rigid and highly flexible.

[0015] According to a third option of any of the first to third aspects, which can be combined with the first or second option, the threaded stylet further comprises an operating handle fixed to an end opposite the coupling end, whereby rotation of the inserted threaded stylet is facilitated via the operating handle.

[0016] According to a fourth option of any of the first to third aspects, which can be combined with any of the first to third options, the operating handle of the threaded stylet further includes an annular opening configured to surround the threaded stylet and accommodate the end of the connector of the lead device, such that the threaded stylet with its integrated operating handle can be easily secured to the lead device by simply continuing the insertion process until the end of the connector of the lead device is inserted into the operating handle.

[0017] According to a fifth option of any of the first to third aspects, which can be combined with any of the first to fourth options, the operating handle of the threaded stylet further includes a locking element for securing the end of the connector of the lead device to the threaded stylet within the annular opening. This allows for a quick and easy locking mechanism to be achieved by simply activating the locking element once the end of the connector of the lead device has been inserted into the operating handle and sufficient connection force has been achieved by elastic elongation of the lead body. The locking element may include a screw, a bolt and hole, or a threaded portion on the operating handle and end to provide the locking mechanism.

[0018] According to a sixth option of any of the first to third aspects, which can be combined with any of the first to fifth options, the locking element of the operating handle of the threaded stylet may be configured to be connectable to a signal analyzer via a cable for transmission of signals from the coupling end to the signal analyzer, thereby allowing a physician to easily connect a lead device with a threaded stylet inserted therein to a signal analyzer to assist in the placement process.

[0019] According to a seventh option of any of the first to third aspects, which can be combined with any of the first to sixth options, the threaded stylet further has an end protruding from the operating handle, to which the signal analyzer is rotatably connected via a cable for signal transmission from the coupling end to the signal analyzer, thereby realizing a cost-saving "in-line" connection with the option for a rotating / sliding electrical connection around the stylet body, for example, via an alligator clamp.

[0020] It is to be understood that the threaded stylet of claim 1, the lead system of claim 9 and the method of claim 10 may have similar and / or identical preferred embodiments, particularly as defined in the dependent claims.

[0021] It is further to be understood that preferred embodiments of the invention can also be any combination of the individual independent and dependent claims or the above embodiments.

[0022] 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]

[0023] [Figure 1] 1 is a flow diagram illustrating a general procedure for placing an LBBP lead device according to various embodiments. [Figure 2] Schematic of a heart with a lead device placed for RVA pacing. [Figure 3]Schematic of the heart with LBB pacing sites indicated. [Figure 4] Schematic of a heart with a lead device placed for ventricular transseptal LBB pacing. [Figure 5] 1 is a diagram schematically illustrating a lead device according to an embodiment. [Figure 6] 1 is a schematic diagram of a lead device according to an embodiment with dimensional parameters shown. [Figure 7] 1A and 1B are schematic diagrams illustrating disassembled and assembled parts of a lead device according to an embodiment. [Figure 8] 1A-1C are schematic diagrams illustrating exploded and assembled portions of an embodiment of a lead device with an improved signal tap. [Figure 9] 1A and 1B are side and cross-sectional views schematically illustrating a driver handle of a screw-in driver stylet in a lead device according to an embodiment. [Figure 10] FIG. 10 is a graph comparing the lead torque with the number of lead turns achieved by the lead device according to the embodiment with that of a conventional lead device. [Figure 11] 1 is a diagram illustrating a lead device having a molded thread structure according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0024] Various embodiments of the present invention are described based on an improved lead system configuration comprising a lead device (e.g., an electrode catheter) and an insertable threaded stylet. The present invention is particularly advantageous in transseptal pacing, such as LBBP, but is not limited thereto, and may be used in conjunction with other pacing types and / or sites in other applications requiring lead device placement.

[0025] It should be noted that throughout this disclosure, only blocks, components, and / or devices relevant to the proposed lead system structure and placement operations are shown in the accompanying drawings. Other blocks have been omitted for reasons of brevity. Furthermore, components designated with the same reference symbol or number are intended to have the same or at least similar functionality, and therefore, their functionality will not be described again hereinafter.

[0026] LBBP is usually defined as capture of the LBB (i.e., the left fascicular trunk or its proximal fiber bundles) with septal myocardial capture at low power (e.g., <1.0 V / 0.4 ms).

[0027] FIG. 1 shows a flow chart of an exemplary procedure for placement or implantation of a lead device for LBBP.

[0028] In the first step S101 ("VST?"), the thickness of the interventricular septum is assessed by echocardiography and / or scar measurements. The IVS separates the LV and RV and plays an important role in the function of both ventricles. As an example, echocardiography can be used to measure septal thickness from the clearest echoes containing the left and right endocardial surfaces at end diastole, which can be determined, for example, by the R-wave peak of a simultaneously recorded ECG.

[0029] Based on the intrinsic cardiac rhythm obtained from ECG measurements, the presence or absence of LBBB is determined in step S102a ("LBBB") or step S102b ("N-LBBB"), respectively. LBBB completely alters the electrical activation of the LV and QRS complexes in the ECG. Under physiological conditions, left-biased septal activation begins on the right side. The electrical impulse then propagates inferiorly, leftward, and slightly anteriorly. This causes a non-uniform and delayed depolarization of the LV.

[0030] Electrocardiographic criteria for LBBB may include at least one of the following: QRS duration of 120 ms or more, absent Q waves in leads I, V5, and V6, monomorphic R waves in leads I, V5, and V6, and ST and T wave displacements opposite the major deflection of the QRS complex.

[0031] A simple way to diagnose LBBB with a widened QRS complex (>120 ms) on the ECG would be to look at lead V1. If the QRS complex is widened and deviated downward in lead V1, LBBB is present. If the QRS complex is widened and deviated upward in lead V1, RBBB is present.

[0032] Once LBBB is determined in step S102a, additional ventricular backup pacing is added in step S103 ("V-BUP").

[0033] With or without LBBB, venous access is performed from the left side via the lead device in step S104 ("VACC(LS)").

[0034] An initial LBBP location is then determined in step S105 on the right surface of the interventricular septum (e.g., at RAO 30°) ("VS(RAO 30°)LBBP"). This is achieved by placing a catheter approximately 1-1.5 cm from the HBP site toward the RVA and / or using a pacing configuration, where a "W" pattern with a notch near the base (the deepest point of the QRS signal) in lead VI may indicate an ideal location. Then, a pacing lead (e.g., a spiral electrode) is screwed perpendicular to the LV septum (LAO 30-45°).

[0035] If an error ("ERR") is determined in step S105 due to fixation failure, a re-evaluation is initiated ("RASS") in step S106.

[0036] Then, in step S107 ("DET LD"), the LBBP lead depth into the ventricular septum is determined, which may be accomplished by at least one of observing notch changes in lead VI, sheath angiography, fulcrum sign, and impedance monitoring.

[0037] The pacing lead is advanced slowly to a depth of approximately 6-8 mm while avoiding septal perforation and / or depending on the RBBB pacing configuration.

[0038] Finally, in step S108 ("CONF LBBP CPT"), LBB capture is confirmed based on acceptable pacing parameters, based on at least one of the following: the paced morphology of the RBBB pattern, recordings of LBB potentials, stimulation peaks of LVAT that shorten rapidly with increasing output or remain short and constant at low and high outputs, selective and non-selective LBBP, and recordings of retrograde His potentials or orthodromic LBB potentials during pacing.

[0039] In summary, common features of the implantation or placement process include transvenous access, transseptal placement of the pacing lead into the LV septal subendocardium in the LBB region, and confirmation of LBB capture.

[0040] In the case of RBBB, the LV is activated earlier than the RV, so when a pacing lead is placed transseptally from the RV septum to the LV septal subendocardium in the LBB region, the pacing QRS morphology on the electrocardiogram changes from LBBB to a right bundle branch block (RBBB) pattern. However, the pacing morphology may be affected by the pacing site of the LBB, pre-existing bundle branch disease, or selective or non-selective LBB capture.

[0041] FIG. 2 shows a schematic of a heart with a lead device placed for RVA pacing.

[0042] In normal cardiac function, the heartbeat begins within the heart itself, with the SAN, found at the top of the RA, which sets the rate at which the heart contracts. The SAN sends out electrical impulses that are conducted through the muscular walls of both atria. These impulses cause atrial contraction. The impulses then travel to another node within the heart, the AVN, which is located below the RA. When the impulse from the SAN reaches the AVN, it is sent to conduction fibers that run down the central wall of the heart. The impulses then separate and travel up the LV and RV, causing them to contract simultaneously (ventricular contraction).

[0043] Key elements of the cardiac conduction system are found within the interventricular septum (IVS) 24. The bundle of His courses subendocardium and descends approximately 1 cm on the right side of the septum 24 before separating into the LBB and RBB. The RBB continues down the right side of the septum 24, while the LBB crosses to the left and divides into anterior and posterior sections.

[0044] Under normal conditions, excitation from the SAN controls the rhythm of the heart. Abnormalities in sinus rhythm lead to arrhythmias, which represent abnormalities in the rate, rhythm, site of origin, and conduction of cardiac electrical impulses. When damage occurs in specific intraventricular conduction fibers, the repolarization wave must travel via slow myo-myosinus conduction to reach the ventricles. Classical disorders associated with conditions involving different conduction bundle branches include LBBB and RBBB. An ECG is used to measure and record cardiac electrical activity and can provide important information about cardiac function. An ECG is used as a standard diagnostic tool to analyze arrhythmias.

[0045] RVA pacing 26 via a lead system 200, including a pacing lead 20, can cause abnormal contraction patterns, resulting in LV free wall and septum 24 dyssynchrony, which can lead to myocardial perfusion defects, histopathological changes, left ventricular dilatation, and both systolic and diastolic left ventricular dysfunction. All of these long-term changes may explain the increased morbidity and mortality seen in patients with chronic RVA pacing 26 compared to atrial pacing.

[0046] Two distinct electrical activation rates can be observed through the heart: a first activation rate (slow conduction / contraction) through myocytes (i.e., muscle cells), indicated by small arrows in Figure 2, and a second activation rate (fast conduction) through Purkinje fibers 22 (i.e., subendocardial branches), which is approximately 10 times faster than the first rate. Purkinje fibers 22 can therefore be viewed as a kind of excitation "highway."

[0047] FIG. 3 shows a schematic of the heart showing LBB pacing sites 28.

[0048] The LBB pacing site 28 is located on the Purkinje fibers 22 of the LV to provide synchronization between the LV free wall and septum 24, activating a more physiological contraction.

[0049] 4 is a schematic illustration of a heart with a lead device 200 inserted, and a pacing lead 20 positioned for ventricular transseptal LBBP. Placement of the pacing lead 20 may be performed according to the procedure described above in connection with FIG.

[0050] This allows the LV to be paced from the RV via a transseptal approach using the ventricle as a guide for catheter delivery.

[0051] The following embodiments of the proposed lead system are configured to minimize the impact of lead device insertion through the septum 24 by reducing the puncture area (e.g., preventing permanent arterial damage), provide enhanced control over the puncture process through an improved torque transmission mechanism with an insertable threaded stylet, and ensure long-term reliability of lead devices exposed to contractile depression of the septum 24 by providing a compact, robust structure and / or continuous flexibility.

[0052] The lead device body can be configured to improve contact slipperiness with a guide catheter used to guide the lead device (e.g., through a blood vessel) to a target region. This can be achieved, for example, by using a small diameter polyurethane (PU) material to allow advancement of the lead body through the guide catheter and the lead tip through the septum 24 with limited force.

[0053] Suitable lead device designs for tachycardia or bradycardia leads can include multilumen, coaxial, and concentric structures, as long as a central lumen is provided for stylet passage. Coaxial leads have an inner conductor extending along the length of the lead to the tip electrode (cathode) arranged in a coil configuration with a central lumen to allow for stylet passage during implantation. This coil is surrounded by a cylindrical length of inner insulation, which may be surrounded by another coil conductor that leads the lead to the ring electrode (anode). A second outer insulation and lead sheath complete the design, protecting the ring conductor from the outside environment. Concentric bipolar leads address some of the concerns of coaxial leads regarding the bulkiness and stiffness of the four-layer design by providing a new conductor and insulation technology in which a single coil extends along the length of the lead (again with a central lumen to allow stylet insertion) and consists of two or four parallel, mutually insulated conductors, one or two of which connect to the cathode and one or two of which connect to the anode. Each conductor may be individually coated with a bonding layer of, for example, ethylene tetrafluoroethylene (ETFE) fluoropolymer insulation, which insulates each conductor from the other conductors even when intertwined. A single two-element coil may be coated with a single outer insulating coating.

[0054] Multilumen or coaxial or concentric leads may optionally have fixed, non-retractable helices to minimize size, although retractable helices may be used in conjunction with the described embodiments as well.

[0055] Additionally, the proposed lead system may be configured to provide improved torque capabilities, i.e., the ability to safely transmit torque to the helix (e.g., full lead body torque) and stylet drive compatibility for ease of handling (e.g., push transmission). As an example, a concentric lead with a compatible threaded stylet (threaded driver stylet) may be provided, as described below.

[0056] Regarding the design of the distal end (distality) of the lead device, the ratio between the outer diameter of the helix and the outer diameter of the housing should be greater than 70%, ideally 100%, and an isoprofile distality may be provided to avoid an anterior stopping surface.

[0057] Additionally, a rigid helix may be provided to avoid deformation of the helix during screwing, while a fixed helix (i.e., a lock between the helix and the lead body) may allow for easier handling (i.e., no parasitic tool is required for retractable systems).

[0058] Additionally, design flexibility can be provided by adapting the inter-electrode distance for bilateral pacing to septa 24 of different thicknesses.

[0059] The distal design of the lead device can further be configured to allow smooth and predictable advancement of the lead tip into the septum 24 until the helix (cathode) reaches the desired location in the LV chamber without protruding into the LV chamber, i.e., near the LBB without completely perforating the septum 24.

[0060] Additionally, the design of the lead device can be configured to minimize the energy required to puncture the septum 24. This can be accomplished, for example, by providing the interelectrode section (between the distal helix end and the proximal anode end) with a specialized distal tapered tip having a conical shape.

[0061] Various embodiments of a lead system including a lead device and a separate insertable threaded stylet 55 are described below with reference to FIGS. 5-9 and 11. FIG.

[0062] FIG. 5 schematically illustrates an embodiment of a partially disassembled lead system (threaded stylet 55 not yet fully inserted) partially introduced into the septum 24, for example, depending on the desired depth required for LBBP.

[0063] The proposed lead system has a helix 51 attached (e.g., welded) to a driver 52, which may have a surrounding coil 58 or other non-planar regular or irregular surface structure, ensuring good adhesion between the driver 52 and the surrounding material of the lead body 54 in the inter-electrode region, resulting in a simple, rigid, and durable structure of the lead tip with fewer parts for improved long-term reliability. The driver 52 is fixedly supported on the lead body 54 and is mechanically and electrically connected to a threaded stylet adapter 53 adapted for insertion of a mating end (engagement portion) 56 of a separate threaded stylet 55 having a threaded driver function to enable rotational driving of the helix 51 via the driver 52. The electrical signal sensed by the spiral 51 in the target area is sent to a signal analyzer via the threaded stylet 55 through the electrical connection between the spiral 51 and the threaded stylet 55, and can be used, for example, to monitor the correct placement of the spiral 51 during the threading operation without disconnecting the alligator clamp, allowing for a single-step operation (no need for a sequence of threading, clamping, electrical measurement, clamp disconnection, additional threading, clamping, etc.).

[0064] Typical dimensions of the threaded stylet 55 are a nominal diameter in the range of 0.30 mm to 0.50 mm, a reduced diameter of between 0.10 mm and 0.25 mm in the distal section to increase flexibility, and a reduced length of between 0 mm and 200 mm. The threaded stylet can be made from stainless steel (e.g., traditional Inox 304 or 306 in standard versions) or a highly elastic material such as Nitinol, which is more efficient and robust in maintaining torque limits and avoiding the risk of breakage during use.

[0065] In FIG. 5, the threaded stylet 55 is not fully inserted and engaged into the adapter 53 of the driver 52 .

[0066] The adapter 53 may be an integral part of the driver 52 or may be removably or permanently fixed to the driver 52 so as to be compatible with various types of threaded stylets 55 having different shapes or sizes of the coupling end 56.

[0067] In this embodiment, the mating end 56 of the threaded stylet comprises a flat shape (similar to a screwdriver). The adapter 53 has a fitting portion (e.g., a matching slot or recess) for receiving the mating end 56 of the threaded stylet 55.

[0068] More generally, the mating end 56 of the threaded stylet 55 comprises one of a number of cavities or protrusions to allow torque to be applied to the mating portion of the driver 52. Examples include slot drive types, cross drive types, square drive types, multi-square drive types, internal hex drive types, five-pointed star drive types, hex star (Torx®) drive types, combination (plus-slot) drive types, external drive types, or tamper-resistant drive types.

[0069] The proposed configuration of the lead system with driver 52, optional adapter 53 and threaded stylet 55 optimizes torque transfer from the physician's hand to the helix 51 and minimizes friction of the lead body 54 within the guide catheter during placement.

[0070] The lead body 54 further includes an anode 57 and an optional cone-shaped inter-electrode section between the helix 51 (cathode) and the anode 57. Electrical signals (e.g., pacing signals) to the helix 51 and anode 57 are conducted along the lead device by respective insulated wires 59. In the example shown in Figure 5, two insulated wires are used for each electrode (i.e., the welding anode 57 and the cathode of the helix 51).

[0071] 5 allows for a small size (e.g., 4.8F) lead body 54 in combination with PU insulation. Furthermore, a simple and robust structure can be provided with a minimum number of parts to minimize stiffness gradients and the number of welds and / or adhesives or other weak joints.

[0072] The insulating plastic material surrounding the rigid driver 52 can be reflowed onto the driver 52 so that no residual gap remains between these two members that would be subjected to high levels of septum compression, thereby preventing localized bending stresses and the resulting risk of plastic cracking over time.

[0073] FIG. 6 shows the lead system of FIG. 5 with a fully inserted threaded stylet 55, illustrating the outer diameter Dl of the distal portion of the lead housing at the helix 51, the outer diameter Dh of the helix 51, the outer diameter Da of the proximal welding anode 57, the length Lh of the helix 51, and the overall length Lt of the lead tip, including the distal helix 51 and the tapered or conical portion of the lead body 54 that surrounds the driver 52 between the helix 51 and the proximal anode 57.

[0074] The ratio Dh / Dl is set between 0.8 and 1, while Dh can be set between 1 and 1.8 mm (preferably 1.40 mm), Da between 1.25 mm and 1.94 mm (preferably 1.66 mm), Lt between 8 and 15 mm, and Lh between 1.5 and 5 mm.

[0075] The proposed specific conical shape with the above-mentioned dimensional range ensures that the lead tip with the helix 51 can be used to penetrate tissue at the target area in a controlled and smooth manner, providing a conical profile that minimizes the energy required to perform the penetration.

[0076] FIG. 7 shows a schematic diagram of an assembled and disassembled lead system with a threaded stylet 55 having an integrated operating handle (threaded driver handle) 83 according to an embodiment.

[0077] 7 shows a threaded stylet 55 with an integrated operating handle 83 and a locking element (e.g., a metal lateral locking screw) 85 for securing the threaded stylet 55 to the hollow end 81 of a lead device connector (e.g., an IS1 connector) 82. The threaded stylet 55 has a distal portion with a tapered conical section that connects to a flexible section with a small diameter and a flattened mating end 56 that couples to the driver 52 of the lead device.

[0078] The middle part of Figure 7 shows a lead device including a helix 51, a driver 52 with an integrated fitting for inserting the connecting end 56 of a threaded stylet 55, a connector 82 and its end 81.

[0079] 7 shows the assembled lead system with the lead device and threaded stylet 55 inserted and coupled, with the helix 51 properly positioned for LBBP to receive the QRS signal from the LBB. The threaded stylet 55 is coupled to the driver 52 by insertion through the hollow end 81 of the catheter's connector 82, and the end 81 of the connector 82 is inserted into the annular opening of an integrated operating handle 83 that surrounds the threaded stylet 55 and is secured via a locking element 85.

[0080] In the embodiment of FIG. 7, a signal analyzer 86 may be connected via a cable (e.g., a pacing system analyzer (PSA) cable) 84 to a locking element 85 that is electrically coupled to the threaded stylet 55 via the end 81 of the catheter's connector 82.

[0081] This allows the QRS signal from the LBB to be transmitted via the helix 51, driver 52, threaded stylet 55, locking element 85 and PSA cable 84 to a signal analyzer 86 which is used to monitor proper placement of the lead device during puncture.

[0082] Note that only schematic functional elements are shown in FIG. 7; wiring for pacing signals, lead tips, and anodes has been omitted for reasons of simplicity.

[0083] 7, the lead body of the lead device can be configured to allow elastic elongation L+Δl (e.g., Δl=1-10 mm) in response to a force applied to the lead body. As a result, the axial elasticity of the connection system generates a compressive force F that ensures stable and secure engagement of the mating end 56 of the threaded stylet 55 with the driver 52 during the placement operation, despite the many constraints associated with the puncture process (pulling, pushing, torque, bending, etc.). It also ensures a temporary electrical connection between the driver 52 and the threaded stylet 55, reducing artifacts or other interference in the electrical signal transferred to the signal analyzer 86.

[0084] The integral operating handle 83 provides a simple "hands-free" locking handle for manipulating the lead device to achieve improved torque transfer from the physician's hand to the helix 51 via the threaded stylet 55 and driver 52.

[0085] The non-retractable fixed spiral 51 facilitates handling of the lead device by eliminating the need for specialized tools for the retraction mechanism, which can be prone to misuse.

[0086] The threaded stylet 55 (which may be provided as a separate, adaptable accessory for the lead device) provides a threaded driver function for high torque transmission during the difficult puncture process. The threaded stylet 55 directly engages the driver 52 at the lead tip, thereby enabling direct and efficient torque transmission to the fixed helix 51. This proposed arrangement also minimizes stress on the internal structures of the lead device (e.g., adhesives and / or welds) during puncture.

[0087] The material and design of the threaded stylet 55 may be selected to achieve high flexibility in the last 10 cm before the coupling end 56 (e.g., via a conical and / or reduced diameter section) so that it can easily pass around two curves in the guide catheter within the heart, avoiding the risk of the tip becoming dislodged from the target area during insertion of the threaded stylet 55. Furthermore, high torque transmission (higher than that of the lead body) is achieved despite the reduced distal diameter and easy "hands-free" locking, and an operating handle 83 is provided for engaging the distal coupling end (e.g., flat end) 56 of the threaded stylet 55 with a mating portion (e.g., a receptacle) in the driver 52 (or adapter 53) for threading operation.

[0088] FIG. 8 shows a schematic representation of the disassembled and assembled portions of an embodiment of a lead device with an improved signal tap provided by a threaded stylet 55 with locking, torque and map functions.

[0089] As with FIG. 7, only schematic functional elements are shown in FIG. 8, with wiring for pacing signals, lead tips, and anodes omitted for reasons of simplicity.

[0090] Here, the operating handle 83 has been modified so that the end of the threaded stylet 55 protrudes from the operating handle 83 and can be used to connect a cable 84, e.g., a PSA cable, to a signal analyzer 86, e.g., via an alligator clamp.

[0091] As such, the body of the threaded stylet 55 extends straight through the operating handle 83 to achieve a cost-saving "in-line" connection with the option of a rotating / sliding electrical connection around the stylet body, for example, via an alligator clamp on the cable 84.

[0092] FIG. 9 shows a schematic perspective view (left side) and a cross-sectional view (right side) of the operating handle 83 of the threaded stylet 55 in the lead device according to the embodiment.

[0093] The wire or body of the threaded stylet 55, which has a flat mating end 56, is secured (such as by molding) to the operating handle 83 and locked in translation and rotation. A lateral locking element 85 can be used to temporarily connect / lock the operating handle 83 to the end (not shown) of a connector (e.g., an IS1 connector pin) of a lead device. The protruding end of the threaded stylet 55 has a connecting end 87 for connecting a cable to a signal analyzer or the like.

[0094] The physician inserts the lead device without the screw stylet 55, for example, through a blood vessel via a guide catheter until the helix 51 reaches the target area, and positions the lead device at the target area. The physician then inserts the threaded stylet 55 until it engages with the driver 52 and pushes the operating handle 83, which is fixed to the threaded stylet 55 at the connector end opposite the coupling end 56, to generate a connecting force between the coupling end 56 of the threaded stylet 55 and the driver 52 through elastic expansion of the lead body 54 of the lead device. Next, the physician locks the position of the operating handle 83 to the lead body 54 using the locking element 85 of the operating handle 83 to maintain the connecting force, and then turns the operating handle 83 (or connector 82) to screw the helix 51 into the target area (e.g., the septum). He / she can also use a temporary electrical connection through the threaded stylet 55 to capture electrical sensing (e.g., the QRS signal) at the helix level to identify when the helix 51 engages the LBB or another target site, allowing for easy one-handed ("hands-free") placement of the helix 51 via the handle 83 (or connector 82).

[0095] Thus, the proposed two-element lead system is configured to temporarily secure or lock both ends of the assembled lead device and threaded stylet 55, with the distal flat end (binding end 56) of the threaded stylet 55 engaging a mating portion of the driver 52 with a predetermined force determined by the elastic elongation of the lead body 54. This can achieve a significant temporary increase in torque transmission along with improved operating comfort during the threading operation critical to placing the lead device. Both the lead device and threaded stylet 55 can be temporarily operated as a single device, freeing up one of the physician's hands.

[0096] FIG. 10 shows a graph comparing the lead torque versus the number of lead turns achieved with the lead system according to the embodiment with that of a conventional lead device.

[0097] This figure shows the improved torque curve 90 achieved with the proposed lead system with a threaded stylet and driver handle compared to a group of torque curves 92 achieved with a conventional lead device and threaded stylet alone.

[0098] More specifically, the improved torque curve 90 corresponds to the sum of the uppermost curve in group 92 (corresponding to the threaded stylet only) and the lead device-only curve (one of the lower curves in group 92). While the threaded stylet alone provides a reasonable torque transfer (approximately a 10% to 20% increase), the sum of both the threaded stylet and the lead body results in a 100% torque increase over the lead device alone. As a result, the temporary connection of both elements of the proposed lead system (threaded stylet and lead device) during lead device placement significantly improves torque transfer and ease of use for the physician. To achieve the same performance without the temporary connection of the two elements, the physician would have to rotate both devices simultaneously at the same speed, which is quite difficult considering the many other things he or she must pay attention to during this critical step (e.g., analyzer signals, patient parameters, etc.).

[0099] As can be seen in FIG. 10, the improved torque curve 90 shows a fairly consistent increase in lead torque with increasing turns, which facilitates smooth and predictable advancement of the lead device spiral into the septum or other target region.

[0100] 11 shows a lead device with a threaded structure 120 molded or otherwise formed or attached to the outer surface of the inter-electrode portion of the lead body 54 between the helix 51 and the welding anode 57. The winding pitch of the threaded structure substantially corresponds to the pitch of the helix 51 to allow smooth insertion of the inter-electrode portion followed by the helix 51 upon tissue puncture in the target area (e.g., the septum) for LBBP.

[0101] Furthermore, the lead device with the threaded structure 120 can be used with or without the threaded stylet described above in connection with other embodiments. In the first case, the lead device of FIG. 11 includes a driver that can be coupled to a threaded stylet.

[0102] It should be noted that the tip dimensions of the lead device of FIG. 11 and the other lead devices of FIGS. 7 and 8 may correspond to those shown in FIG.

[0103] In summary, a threaded stylet is described for improving torque transfer from the physician's hand to the lead tip (e.g., helix) of a lead device. The lead tip is provided for ease of manipulation, and the threaded driver function of the threaded stylet is provided for improving torque transfer to the lead tip of the lead device for better control of the puncture process. The threaded stylet is directly engagable with the lead tip of the lead device, thereby achieving direct and efficient torque transfer to the helix secured to the lead tip.

[0104] While the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are illustrative or exemplary and not restrictive. The present invention is not limited to the disclosed embodiments. The present invention is applicable to various types of lead devices (e.g., bradycardia or tachycardia lead devices having multi-lumen, coaxial, or concentric configurations) and applications in the field of cardiac pacing or sensing systems. Furthermore, a threaded stylet may be provided as an integral element of the lead device that is not detachable from the lead body.

[0105] The proposed threaded stylet system (more precisely, its handle) may be adapted or configured to be adaptable to IS1, IS4 (low voltage) or DF4 (high voltage) connectors, for example, the handle may be configured to provide a temporary connection to all connector rings for mapping purposes.

[0106] In one example, an LBB screw driver handle 83 connects to and covers the IS1 connector, while a lateral locking element (e.g., a metal screw) 85 can engage the IS1 pin to secure the mechanical connection to the lead body structure.

[0107] More specifically, the handle 83 can be connectable to the spiral 51 (through the stylet 55 or through a locking element 85 engaged with the IS1 pin) and the IS1 ring electrode (connected to the anode). This makes the handle 83 more complex but provides a better signal for identifying LBB capture. The connecting element is an axially elongated radial spring that connects to the IS1 ring electrode for line connection, e.g., via an alligator clamp. This concept can also be extended to IS4 and DF4 connectors to connect all four connector poles.

[0108] In another example, compatibility with a retractable helix system may be provided, e.g., for use with a Brady lead system having a retractable helix for LBB treatment. The proposed screw-in driver stylet system provides an advantageous solution for such types of leads as well. In this case, locking element (e.g., a metal screw) 85 may engage with the IS1 pin and / or the IS1 ring. When engaging both types of electrodes, two lateral locking elements (e.g., screws) may be provided in addition to locking element 85: a further locking element configured to engage the IS1 ring. When engaging the IS1 ring, locking element 85 may be configured to face the IS1 ring.

[0109] The IS1 pin may be rotatable and connectable to the inner coil structure to actuate helix extension of the retractable helix system.

[0110] Other variations to 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 articles "a" or "an" do 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 foregoing description details particular embodiments of the invention. However, no matter how detailed the foregoing appears herein, it will be understood that the invention can be embodied in many ways and is not limited to the disclosed embodiments. It should be noted that the use of a particular term in describing a particular feature or aspect of the invention does not imply that the term be redefined herein to be limited to include the specific features of the feature or aspect of the invention with which the term is associated.

Claims

1. A threaded stylet (55) configured to be insertable into a lead body (54) of a lead device, and having a coupling end (56) configured to be engageable with a driver (52) of the lead tip to transmit torque to the lead tip of the lead device.

2. 2. The threaded stylet (55) of claim 1, further comprising a conical portion and / or a reduced diameter portion at the coupling end (56) to increase flexibility of the distal portion.

3. 3. The threaded stylet (55) of claim 1 or claim 2, characterized in that it is made of stainless steel or nitinol.

4. 4. The threaded stylet (55) according to any one of claims 1 to 3, further comprising an operating handle (83) fixed to an end opposite the coupling end (56).

5. The threaded stylet (55) of claim 4, characterized in that the operating handle (83) has an annular opening that surrounds the threaded stylet (55) and is configured to accommodate the end (81) of the connector (82) of the lead device at the end opposite the lead tip.

6. The threaded stylet (55) of claim 5, characterized in that the operating handle (83) has a locking element (85) for securing the end (81) of the connector (82) of the lead device to the threaded stylet (55) within the annular opening.

7. The threaded stylet (55) of claim 6, characterized in that the locking element (85) is configured to be connectable to a signal analyzer (86) via a cable (84) for transmitting signals from the coupling end (56) to the signal analyzer (86).

8. A threaded stylet (55) as described in any one of claims 1 to 7, characterized in that it has an end protruding from the operating handle (83), to which the signal analyzer (86) is rotatably connected via a cable (84) for signal transmission from the coupling end (56) to the signal analyzer (86).

9. A lead system comprising: a threaded stylet (55) according to any one of claims 1 to 8; and a lead device having a lead tip provided with a driver (52) configured to be engageable with a coupling end (56) of the threaded stylet (55) when the threaded stylet (55) is inserted.

10. 1. A method for transmitting torque to a lead tip of a lead device positioned in a target region of a human or animal body, comprising: Inserting the threaded stylet (55) into the lead device until the mating end (56) of the threaded stylet (55) engages the driver (52) of the lead tip; pushing an operating handle (83) fixed to the threaded stylet (55) at a connector end opposite the coupling end (56), thereby generating a connection force between the coupling end (56) of the threaded stylet (55) and the driver (52) by elastically stretching the lead body (54) of the lead device; locking the operating handle (83) to the lead body (54) using a locking element (85) of the operating handle (83) to maintain the connection force; rotating the threaded stylet (55) to transmit torque to the lead tip through the driver (52).

Images