Biostimulator delivery system with tethered cable

Abstract

A biological stimulator delivery system with a tether cable is described. A connector can be mounted on the tether cable to connect to the biological stimulator. The connector can be a protrusion housed within the biological stimulator or a threaded connector that is screwed into the biological stimulator. The tether cable has a strand cable construction including a plurality of strands extending around a core strand in a helical direction. The strand cable construction resists breakage under bending stresses that typically occur during tethering modes used in biological stimulator delivery processes. The tether cable reliably secures the biological stimulator to the delivery system in the tethering modes. Other embodiments are also described and claimed.

Description

Technical Field

[0001] This disclosure relates to biostimulators and related transport systems. More specifically, this disclosure relates to a transport system for delivering leadless biostimulators. Background Technology

[0002] When the heart's natural pacemaker and / or conduction system cannot provide synchronized atrial and ventricular contractions at a rate and interval sufficient for a patient's health, an artificial pacemaker provides electrical stimulation to the heart. This bradycardia pacing has provided symptom relief and even life support for thousands of patients. Cardiac pacing can also provide electrical overdrive stimulation to suppress or convert tachyarrhythmias, again relieving symptoms and preventing or terminating arrhythmias that could lead to sudden cardiac death.

[0003] Leadless pacemakers integrate electronic circuitry at the pacing site and eliminate leads, thus avoiding the drawbacks associated with traditional pacing systems. Leadless pacemakers can be anchored at the pacing site, such as in the right ventricle, or in the right atrium for biventricular pacing. Delivery systems can be used to deliver the leadless pacemaker to the target anatomical structure. Summary of the Invention

[0004] Existing leadless biostimulator systems may have a tether assembly to attach the leadless biostimulator to a catheter-based delivery system. The tether assembly may employ a tether manufactured by grinding a profile into a continuous length of wire. A grounding wire may include a protrusion or "bullet" at its distal end, which may be located within the leadless biostimulator to releasably connect the biostimulator to the delivery system. Before releasing the biostimulator at the target anatomical structure, the delivery system can operate in a "tethered mode," where the leadless biostimulator is freely supported by the tether assembly without additional support from the catheter of the delivery system. In tethered mode, the tether of the tether assembly is subjected to considerable bending stress, which can potentially lead to fatigue failure of the tether material. Such failure (e.g., tether breakage) could result in undesirable loss of the leadless biostimulator within the patient's anatomy. Therefore, there is a need for a biostimulator delivery system with a tether assembly that resists breakage under the bending stresses experienced during tethered mode.

[0005] A biostimulator delivery system with a tethered cable is described. In one embodiment, the delivery system includes an elongated catheter extending from a handle to a docking cap. The docking cap is rotatably coupled to the elongated catheter. For example, a torque cable may extend from the handle to the docking cap, and torque may be transmitted via the torque cable to rotate the docking cap relative to the elongated catheter. The docking cap may include a docking cavity to receive attachment features of the biostimulator, so rotation of the docking cap may also rotate the biostimulator. Thus, the delivery system can rotate the biostimulator to drive the fixation element of the biostimulator into the target tissue.

[0006] The biostimulator can be held relative to an elongated catheter via a tether assembly. The tether assembly can extend from the handle, through the elongated catheter, and into the attachment feature of the biostimulator. For example, the tether assembly may include a connector at the distal end of the tether cable, and this connector may be accommodated within and / or screwed into the attachment feature to connect the biostimulator to a delivery system via the tether cable. For example, the biostimulator can be held in a tethered mode, in which the biostimulator is freely supported on the tether cable, which is away from the docking cap and without the support of the docking cap. In the tethered mode, the tether cable can undergo significant bending patterns within the beating heart.

[0007] The tethered cable can be configured to bend freely and resist breakage under bending patterns experienced during use. In one embodiment, the tethered cable includes a core strand surrounded by multiple side strands. For example, a first set of side strands may extend around the core strand in a first helical direction. The cable may be multi-layered. For example, a second set of side strands may extend around the core strand in a second helical direction between the core strand and the first set of side strands. The first and second helical directions may be opposite to each other to contribute to effective torsion resistance.

[0008] In one embodiment, the delivery system includes multiple tethers in a tether assembly. For example, a first tether and a second tether may extend parallel to each other. The tethers may include corresponding connectors at their distal ends to engage channels of attachment features. More specifically, the connectors may be aligned to be received within the channels. Thus, a dual-tether configuration allows the delivery system to be attached to a biostimulator.

[0009] In one embodiment, the delivery system includes a single tether in a tether assembly. For example, the single tether cable may include a threaded connector located at the distal end of the cable. The threaded connector can engage mating threads in a channel of the attachment feature and can therefore be screwed into the attachment feature. Thus, a single tether configuration allows the delivery system to be attached to a biostimulator.

[0010] The delivery system may include a support tube, such as a hyaluronic acid tube, extending from the handle to the proximal end of the tether cable. The support tube can effectively transfer axial loads to the tether cable. The delivery system may also include a retaining coil for the tether around the double tether assembly. The retaining coil can restrain the tether cable to reduce the possibility of cable misalignment, which could lead to connector misalignment and unintentional detachment from the attachment feature.

[0011] The above overview does not constitute an exhaustive list of all aspects of the invention. The invention is intended to encompass all systems and methods that can be implemented from all suitable combinations of the aspects summarized above, as well as those disclosed in the detailed description below and specifically pointed out in the claims filed with this application. Such combinations have particular advantages not specifically listed in the above overview. Attached Figure Description

[0012] The novel features of the invention are set forth in detail in the following claims. A better understanding of the features and advantages of the invention will be obtained by referring to the following detailed description and accompanying drawings, which illustrate illustrative embodiments in which the principles of the invention are utilized.

[0013] Figure 1 This is a schematic cross-section of a patient's heart according to one embodiment, illustrating an example of implanting a biostimulator in a target anatomical structure.

[0014] Figure 2 This is a perspective view of a biostimulator transport system according to one embodiment.

[0015] Figure 3 This is a distal perspective view of a biostimulator transport system according to an embodiment, the system having a docking cap for receiving a biostimulator.

[0016] Figure 4 This is a side view of a leadless biostimulator according to one embodiment.

[0017] Figure 5-6 This is a cross-sectional view of a tether assembly with attachment features for engaging and releasing a biostimulator according to one embodiment.

[0018] Figure 7 This is a perspective view of a tethering assembly according to one embodiment.

[0019] Figure 8 This is a cross-sectional view of a tethered cable according to one embodiment.

[0020] Figure 9 This is a side view of a tether assembly including a retaining coil according to one embodiment.

[0021] Figure 10 This is a cross-sectional view of a biostimulator delivery system according to an embodiment.

[0022] Figure 11 This is a perspective view of a tethering assembly according to one embodiment.

[0023] Figure 12 This is a cross-sectional view of a tethered cable according to one embodiment.

[0024] Figure 13 This is a cross-sectional view of the attachment features of a biostimulator according to one embodiment.

[0025] Figure 14 This is a side view of a threaded connector of a tether assembly for attaching a biostimulator according to an embodiment.

[0026] Figure 15 This is a cross-sectional view of a biostimulator delivery system according to an embodiment. Detailed Implementation

[0027] The embodiments describe a biostimulator delivery system with a tethered cable, such as a biostimulator delivery system. As described below, the biostimulator delivery system can be used to deliver a biostimulator to a patient's heart to pace cardiac tissue. However, the biostimulator can be used for other applications, such as deep brain stimulation. Therefore, referring to the biostimulator as a cardiac pacemaker is not limiting.

[0028] In various embodiments, reference is made to the accompanying drawings. However, some embodiments may be implemented without one or more of these specific details, or in combination with other known methods and configurations. Numerous specific details, such as specific configurations, dimensions, and processes, are set forth in the following description to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques are not described in particular detail to avoid unnecessarily obscuring the description. Throughout the specification, references to “an embodiment,” “an embodiment,” etc., mean that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment. Therefore, phrases “an embodiment,” “an embodiment,” etc., appearing in different places throughout the specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, configuration, or characteristic may be combined in any suitable manner.

[0029] The use of relative terms throughout this specification may indicate relative position or direction. For example, "distal" may refer to a first direction along the longitudinal axis of the tethered cable. Similarly, "proximal" may refer to a second direction opposite to the first direction. However, these terms are provided to establish relative frames of reference and not to limit the use or orientation of the biostimulator delivery system to the specific configurations described in the various embodiments below.

[0030] In one aspect, the biostimulator delivery system includes a tether assembly for connecting the delivery system to a leadless biostimulator. The tether assembly includes a flexible yet robust tether cable. More specifically, the tether cable has a stranded cable construction comprising multiple lateral strands spirally wound around a core strand. Each strand has a smaller diameter, thus the bending stress experienced by each strand is lower than that experienced by a tether of similar size formed from a single strand. Therefore, for a given bending radius, the bending stress experienced by the tether cable can be reduced, allowing the tether assembly to safely and reliably hold the biostimulator during delivery to the target anatomical structure.

[0031] refer to Figure 1 According to one embodiment, a schematic cross-section of a patient's heart is shown, illustrating an example of implantation of a biostimulator in a target anatomical structure. The cardiac pacing system includes one or more biostimulators 100 and a biostimulator delivery system, such as a biostimulator delivery system 101. The biostimulator delivery system 101 can deliver the biostimulator 100 to a corresponding target anatomical location in the patient's heart 104. Alternatively, the biostimulator delivery system can retrieve the biostimulator 100 from the patient's heart 104.

[0032] The biostimulator 100 may be leadless, for example, it may be a leadless cardiac pacemaker. Each biostimulator 100 may be placed in a cardiac chamber, such as the right atrium and / or right ventricle of a patient's heart 104. Delivery (or retrieval) of the biostimulator 100 is facilitated by attaching the biostimulator 100 to the distal end of the biostimulator delivery system 101. More specifically, the biostimulator delivery system 101 may be connected to an attachment feature 102 of the biostimulator 100.

[0033] The biostimulator 100 can be attached to the interior or exterior of the heart chamber. Attachment of the biostimulator 100 to target tissue can be achieved via one or more fixation elements 106, such as helical anchors. Alternatively, one or more fixation elements may include outwardly flared splines that engage the target tissue to attach the biostimulator 100 to a target anatomical structure. In a particular embodiment, the leadless pacemaker may use two or more electrodes located on or within the leadless pacemaker housing for pacing the heart chamber upon receiving a trigger signal from internal circuitry and / or from at least one other device within the body.

[0034] refer to Figure 2The image shows a perspective view of a biostimulator delivery system according to one embodiment. The biostimulator delivery system can be used to deliver and / or retrieve a biostimulator 100 (e.g., a leadless pacemaker) into and / or from a patient. For example, the biostimulator delivery system can be a biostimulator delivery system 101 for delivering the biostimulator 100 into a patient. Alternatively, the biostimulator delivery system can be a biostimulator retrieval system. For simplicity, the delivery system will be referred to primarily as a delivery system below; however, this reference is non-limiting.

[0035] The biostimulator delivery system 101 may include a handle 202 and an elongated catheter 204 extending distally from the handle 202 to a distal catheter tip. The handle 202 may include multiple portions and features that allow a user to provide input proximally to the system, which is then translated into output at the distal end of the system. For example, the elongated catheter 204 may be a deflectable catheter, and an operator may use the handle 202 to manipulate the distal catheter tip within the patient's body. In one embodiment, the handle 202 includes a deflection lever 206 for deflecting the distal catheter tip. By pivoting the deflection lever 206 toward the distal handle portion 208 of the handle 202, an operator can apply off-axis compression to the elongated catheter 204 via a pull-ring assembly, resulting in lateral deflection of the distal catheter tip.

[0036] Handle 202 can be used to apply torque to docking cap 210 at the distal end of the system. Docking cap 210 can be rotatably coupled to elongated conduit 204. In one embodiment, handle 202 includes a first handle portion 212. The first handle portion 212 can rotate and / or move longitudinally relative to the distal handle portion 208. For example, the distal handle portion 208 can be coupled to elongated conduit 204, and the first handle portion 212 can be coupled to a torque shaft (…). Figure 10 The operator can rotate the first handle portion 212 relative to the distal handle portion 208 so that the docking cap 210 rotatably connected to the first handle portion 212 rotates relative to the elongated conduit 204 rotatably connected to the distal handle portion 208.

[0037] In one embodiment, the handle 202 can be used to induce longitudinal or rotational movement of the tether assembly 214 of the biostimulator delivery system 101. The handle 202 may include a second handle portion 216. Movement of the second handle portion 216 relative to another handle portion (e.g., the first handle portion 212) can result in relative movement between one or more tethers of the tether assembly 214 and / or another component of the biostimulator delivery system 101. For example, longitudinal movement of the second handle portion 216 relative to the first handle portion 212 can result in longitudinal movement of the first tether of the tether assembly 214 relative to the second tether of the tether assembly 214. Alternatively, longitudinal movement of the first handle portion 214 and the second handle portion 216 relative to the distal handle portion 208 can result in movement of the tether relative to the docking cap 210.

[0038] In one embodiment, the biostimulator delivery system 101 includes a protective sheath 220 mounted on an elongated catheter 204. The protective sheath 220 may be slidably disposed on the elongated catheter 204. The protective sheath 220 may include a damage-resistant end 222, such as a flexible, funnel-shaped distal portion, which may slide distally on the distal end of the elongated catheter 204 and / or the biostimulator 100 (not shown). The external dimensions of the damage-resistant end 222 may be larger than the proximal portion of the protective sheath 220. For example, the damage-resistant end 222 may open distally toward a funnel opening that can advance over a docking cap 210 of the biostimulator delivery system 101. The external dimensions of the damage-resistant end 222 may be larger than the area of ​​the protective sheath 220 that supports the valve bypass tool 224.

[0039] The valve bypass tool 224 can be slidably disposed on the protective sheath 220, such that the distal portion of the valve bypass tool 224 can slide distally on the distal end of the elongated catheter 204 and / or the damage-resistant end 222 of the protective sheath 220. More specifically, the valve bypass tool 224 can be inserted into the guide to access the patient's vascular system, and after access is established, the distal portion of the protective sheath 220 and / or the distal end of the elongated catheter 204 can be advanced into the patient's body through the valve bypass tool 224.

[0040] The valve bypass tool 224, the protective sheath 220, and the elongated catheter 204 may have respective flushing ports 226a, 226b, and 226c extending therefrom. Each longitudinal body is movable proximally to distally relative to each other, so that the flushing ports can be used to introduce and / or flush saline or other fluids between the longitudinal bodies or through the respective components at different relative positions.

[0041] refer to Figure 3The image shows a distal perspective view of a biostimulator delivery system with a docking cap for receiving a biostimulator according to one embodiment. The distal end of an elongated conduit 204 is selectively connected to the biostimulator 100. More specifically, the biostimulator delivery system 101 may include a tether assembly 214 extending from a handle 202 through the elongated conduit 204 to engage the biostimulator 100. Thus, the biostimulator 100 can be mounted on the distal end of the elongated conduit 204. In one embodiment, the biostimulator 100 includes an attachment feature 102. The attachment feature 102 may be, for example, a proximal extension from the housing 302 of the biostimulator 100. In one embodiment, the attachment feature 102 includes a channel shaped and sized to receive one or more tethers of the tether assembly 214. Figure 5-6 (and 13). More specifically, the tether assembly 214 may include a tether cable 304 and a connector 306, sized to fit within a channel. The connector 306 may be located at the distal end of the tether cable 304 and may be directly connected, for example by screwing into a mating connector of attachment feature 102, or indirectly connected, for example by being accommodated within a channel of attachment feature 102. Thus, the tether assembly 214 may connect the biostimulator 100 to the biostimulator delivery system 101.

[0042] In one embodiment, the docking cap 210 includes a docking cavity 308. The docking cavity 308 is sized and shaped to receive an attachment feature 102. More specifically, the attachment feature 102 may have a shape and size that fits within the docking cavity 308. When the tether of the tether assembly 214 is locked within the attachment feature 102, the tether can retract to pull the biostimulator 100 toward the docking cap 210. As the biostimulator 100 moves toward the docking cap 210, the attachment feature 102 can be inserted into the docking cavity 308. Thus, the docking cavity 308 can receive the attachment feature 102 to dock the biostimulator 100 to the biostimulator delivery system 101 for delivery or retrieval from a patient.

[0043] refer to Figure 4 The image shows a side view of a leadless biostimulator according to one embodiment. The biostimulator 100 can be a leadless cardiac pacemaker capable of performing cardiac pacing and possessing many advantages of conventional cardiac pacemakers while extending performance, functionality, and operational characteristics. The biostimulator 100 may have two or more electrodes, such as a distal electrode 402 and a proximal electrode 404, located within, above, or near a housing 302 of the biostimulator 100. In one embodiment, a fixation element 106 forms part of the distal electrode 402. The electrodes can deliver pacing pulses to the muscles of the heart chambers and, optionally, can sense electrical activity from the muscles. The electrodes can also communicate bidirectionally with at least one other device, either inside or outside the body.

[0044] In one embodiment, housing 302 has a longitudinal axis 406, and distal electrode 402 may be a distal pacing electrode mounted on housing 302 along the longitudinal axis 406. Housing 302 may contain a primary battery to provide power for pacing, sensing, and communication (which may include, for example, bidirectional communication). Housing 302 may optionally contain an electronics compartment 408 to house circuitry suitable for various functions. For example, electronics compartment 408 may contain circuitry for sensing cardiac activity from the electrodes, circuitry for receiving information from at least one other device via the electrodes, circuitry for generating pacing pulses delivered via the electrodes, or other circuitry. Electronic compartment 408 may contain circuitry for transmitting information to at least one other device via the electrodes, and may optionally contain circuitry for monitoring device health. The circuitry of biostimulator 100 may control these operations in a predetermined manner. In some embodiments of the cardiac pacing system, cardiac pacing is provided without requiring a pulse generator located in the chest or abdomen, electrode leads separate from the pulse generator, communication coils or antennas, or additional battery power for transmitting communication.

[0045] Leadless pacemakers or other leadless biostimulators 100 can be secured to the intracardiac implantation site via one or more active engagement or fixation mechanisms, such as screws or helical members (or optionally, teeth) screwed into the myocardium. In one embodiment, the biostimulator 100 includes a fixation element 106 coupled to the housing 302. The fixation element 106 may be a helical element screwed into the target tissue. More specifically, the fixation element 106 may extend helically from the flange 410 of the biostimulator 100 mounted on the housing 206 to a distal helical end 412.

[0046] The distal helical tip 412 can be located distal to the distal electrode 402 (the centrally located electrode). Therefore, when the biostimulator 100 contacts the target tissue, the distal helical tip 412 can pierce the tissue, and the housing 302 can be rotated to screw the fixation element 106 into the target tissue, thereby pulling the distal electrode 402 into contact with the tissue. Alternatively, the housing 302 can be rotated to unscrew the fixation element 106 from the target tissue, thereby retrieving the biostimulator 100.

[0047] Reference Figure 5A cross-sectional view of a tether assembly for attaching a biostimulator according to one embodiment is shown. The tether assembly 214 may include a plurality of tethers 502. In one embodiment, the tether assembly 214 includes a first tether 504 and a second tether 506. Each tether of the tether assembly 214 may have a respective connector 306 and tether cable 304. For example, the first tether 504 may include a first connector 508 mounted on a first tether cable 510. Similarly, the second tether 506 may include a second connector 512 mounted on a second tether cable 514.

[0048] When the tether connector 306 is placed within the channel of attachment feature 102 and aligned in the axial direction, for example, with a plane transverse to the longitudinal axis passing through both connectors 306, the connectors 306 are aligned and the leadless pacemaker is engaged with the delivery system. When aligned, the overall size of the connector 306 can be larger than the channel inlet, so the connector can engage the step in the channel 520 to connect attachment feature 102 to tether assembly 214.

[0049] exist Figure 5 In the diagram, the biostimulator 100 is shown in tethered mode. After the biostimulator 100 is attached to the target tissue, the tether assembly 214 can remain engaged with the attachment feature 102 while the docking cap 210 retracts from the attachment feature 102, allowing the biostimulator 100 to be loosely connected to the delivery system. The tether assembly 214 can remain engaged with the attachment feature 102 because the combined cross-sectional dimensions of the connector 306 can be larger than the dimensions of the channel 520 leading to the attachment feature 102. Therefore, the tether assembly 214 can be accommodated within the channel 520 to connect the biostimulator 100 to the biostimulator delivery system 101.

[0050] In tethered mode, the biostimulator 100 is held by only two flexible tethers 502 and is not rigidly attached to the biostimulator delivery system 101. When the biostimulator delivery system 101 is in tethered mode, the tether assembly 214 can apply minimal force to the attachment feature 102, thus simulating the movement of the biostimulator 100 in a free state (e.g., after the biostimulator 100 is released from the biostimulator delivery system 101). Therefore, the integrity of the biostimulator 100 attached to the target tissue can be evaluated. The electrical properties of the biostimulator 100 can also be evaluated in tethered mode. For example, threshold voltage (the minimum voltage required to deliver a pacing pulse to cardiac tissue), impedance, and injury current can be evaluated in tethered mode before the biostimulator 100 is released from the biostimulator delivery system 101.

[0051] In the tethered mode, the movement of the biostimulator 100 can be quite dynamic, and can apply considerable bending stress to the tether 502. This bending stress can lead to fatigue failure of the tether material. For example, if the tether 502 is formed from a single wire (a nickel-titanium wire ground into its final shape with a protruding connector 306 at the distal end of the tether body), the bending stress experienced by the tether may exceed the tether strength, and the tether may crack or break near the attachment feature 102. On the other hand, as described below, the tether 502 formed from the tether cable 304 can be very flexible and resistant to fatigue failure.

[0052] refer to Figure 6 A cross-sectional view of a tether assembly for releasing a biostimulator according to an embodiment is shown. The tether 502 may be misaligned in the axial direction to release the biostimulator 100 at a target site. For example, a first handle portion 212 may be connected to a first tether 504, a second handle portion 216 may be connected to a second tether 506, and relative movement between the handle portions may cause misalignment of the corresponding connectors 306 of the tether 502. When misaligned, the combined lateral dimension of the connectors 306 may be smaller than the dimension of the channel 520 entering the attachment feature 102, and the tether assembly 214 can therefore retract and be removed from the attachment feature 102. More specifically, the tether assembly 214 can be removed from the attachment feature 102 to release the biostimulator 100 from the biostimulator delivery system 101.

[0053] refer to Figure 7 The diagram shows a perspective view of a tether assembly according to one embodiment. To reduce the bending stress experienced by one or more tethers 502 of the tether assembly 214, the diameter of the tether body can be reduced. Bending stress is proportional to the diameter of the lines constituting the tether body; therefore, for a given bending radius, the stress can be reduced by decreasing the cross-sectional dimensions of the constituent portions of the tether body.

[0054] In one embodiment, each tether 502 of the tether assembly 214 includes a tether cable 304 having multiple strands 701 forming the tether body to minimize the cross-sectional dimensions of the constituent portion of the tether body. The tether cable 304 may include multiple strands 701, and one or more strands may extend about the central axis of the tether cable 304 in a first helical direction 702. The strands 701 may be wound around the central axis between the proximal cable end and the distal cable end 704 at the handle 202. Multi-strand stranded cables can provide the same tensile strength as solid wires but may be more flexible and fatigue-resistant.

[0055] As described below, a multi-strand stranded cable can be a cable formed from metal filaments, or it can be a fiber cable formed from strands or filaments of other materials. For example, the stranded cable can be a fiber thread or yarn comprising fibers wound around a central axis to form a tethered structure. The fibers can be polymers or non-metallic fibers. In one embodiment, the fibers form a fiber yarn that provides the multi-strand stranded cable with the same tensile strength as a solid wire, but with greater flexibility and fatigue resistance. The fiber yarn can be a textile, such as having twisted, braided, or otherwise interwoven fibers to form a flexible yet robust tethered structure.

[0056] Connector 306 can be attached to tether cable 304 at the distal cable end 704. For example, connector 306 may have an annular cross-sectional profile, such as tubular, and tether cable 304 may extend through a central hole in the annular connector 306. Connector 306 can then be attached to tether cable 304, for example, using mechanical, thermal, or adhesive bonding. For example, connector 306 can be attached to tether cable 304 by crimping, forging, welding, etc. In one embodiment, the distal end 706 of connector 306 may have an inlet end to provide smooth engagement into the channel 520 of attachment feature 102. For example, the distal end 706 may be dome-shaped, have a bevel, or include another transition surface between the distal face of connector 306 and the sidewall of connector 306.

[0057] refer to Figure 8 A cross-sectional view of a tethered cable according to one embodiment is shown. The tethered cable 304 may be a multi-strand cable of constant diameter. In one embodiment, the tethered cable 304 includes a core strand 802 and multiple strands 701 extending around the core strand 802, such as a first multiple strands 804. The core strand 802 may extend longitudinally along the central axis of the tethered cable 304. In contrast, the strands 701 wound around the core strand 802 may be radially offset from the central axis and may be twisted around the core strand 802, for example, in a first helical direction 702.

[0058] In one embodiment, each strand 701 is formed of the same material. For example, the core strand 802 and the filaments wound around the core strand 802 can be formed of a cobalt-based metal alloy. Cobalt-based metal alloys can provide greater hardness than nickel-titanium alloys, although the latter can also be used to form filaments.

[0059] The strands 701 of the multi-strand tether cable 304 can have the same strand size. For example, each strand can have a wire diameter of 0.0022 inches. In the case of a 1×6 design, i.e., one center strand surrounded by six outer strands, the combined size of the tether cable 304 can be 0.0066 inches. However, in one embodiment, the outer strands can be forged to produce a circular outer profile of the tether cable 304 and combined with the cable strands. In this case, the core strand 802 can have a circular cross-sectional profile, and the first multi-strand strands 804 can have a non-circular cross-sectional profile. For example, the outer cable strands 804 can be modified to have... Figure 8 The flat shape shown. Therefore, for example, the combined size can be reduced from 0.0066 inches to 0.0063 inches.

[0060] refer to Figure 9 The image shows a side view of a tether assembly including a retaining coil according to one embodiment. The multi-wire construction of the tether cables can be flexible, and the tether bodies may tend to bend outwards and away from each other when the tether assembly 214 is positioned in a curve or otherwise exhausted. Having a stable structure to ensure that the tethers 502 remain close to each other even in this situation may be beneficial, as bending of the tether bodies can lead to undesirable misalignment of the connector 306. Therefore, in one embodiment, the biostimulator delivery system 101 includes a retaining coil 902 that restrains a first tether cable 510 and a second tether cable 514. The retaining coil 902 may include a single strand of wire wound into a dense coil wound around an inner cavity. Thus, the single strand of wire provides a coil wall around the inner cavity. The first tether cable 510 and the second tether cable 514 may extend through the inner cavity of the retaining coil 902. Figure 10 This allows the coil to restrain the lateral movement of the first tether cable 510 relative to the second tether cable 514. When the tether cable 304 is thus restrained, the central axes of the cables remain closely spaced, rather than taking a forked path that could lead to connector misalignment and accidental release of the biostimulator 100.

[0061] refer to Figure 10 The diagram shows a cross-sectional view of a biostimulator delivery system according to one embodiment. The retaining coil 902 may have a distal end near the distal cable end 704 of the tether 502 and may extend proximally via the docking cap 210. More specifically, the retaining coil 902 may be longitudinally close to the distal cable ends 704 of the first and second tethers 510, 514.

[0062] In one embodiment, the tether assembly 214 includes one or more support tubes 1002 extending from the handle 202 to the tube end 1004. For example, the tether assembly 214 may include a first support tube 1002 terminating at a first tube end 1010 and a second support tube 1002 terminating at a second tube end 1012. A tether cable 304 may be coupled to the tube end 1004 and extend from the tube end 1004 to a corresponding connector 306. More specifically, a first tether cable 510 may be coupled to the first tube end 1010 and extend from the tube end to a first connector 508. Similarly, a second tether cable 514 may be coupled to the second tube end 1012 and extend from the tube end to a second connector 512. Thus, the tether cable 304 can extend distally from the support tube 1002 through the cavity 1020 of the retaining coil 902 to the corresponding connector 306.

[0063] The connector 306 and support tube 1002 can be sized to hold the retaining coil 902 on the tether assembly 214. More specifically, the inner cavity 1020 of the retaining coil 902 can have an inner diameter smaller than the combined cross-sectional size of the first and second support tubes 1002. Similarly, the combined cross-sectional size of the first connector 508 and the second connector 512 can be larger than the inner diameter. Therefore, the retaining coil 902 can slide longitudinally along the tether cable 304, but can be prevented from sliding out of the tether assembly 214, i.e., beyond the connector 306 distally and beyond the support tube 1002 proximally.

[0064] In one embodiment, the support tube 1002 is a thiocyanate tube. The thiocyanate tube may have solid walls, which provide sufficient rigidity to the tether assembly 214 to allow longitudinal movement to be transmitted from the handle 202 to the tether cable 304. The proximal cable end 1022 of the tether cable 304 may be mechanically attached to the support tube 1002. For example, the tether cable 304 may be inserted into the cavity of the thiocyanate tube, and the thiocyanate tube may be forged or pressed onto the proximal cable end 1022.

[0065] The above about Figure 5-10 The described biostimulator delivery system 101 includes a non-limiting example of a tether assembly 214 with a cable tether 502. However, other tether assemblies including a tether cable 304 are contemplated. More specifically, the tether cable structure and / or connector structure can be modified while achieving the same benefits of tether flexibility and fatigue resistance.

[0066] Reference Figure 11The diagram shows a perspective view of a tether assembly according to one embodiment. The tether assembly 214, extending from the handle 202 through the elongated conduit 204, may include a threaded connector 1102 located at the distal cable end 704 of the tether cable 304. More specifically, the connector 306 may include a threaded portion 1104 configured to screw into an attachment feature 102 of the biostimulator 100. The threaded portion 1104 may be machined into a connector body, and the connector body may be attached to the tether cable 304 via a joining process such as welding, crimping, or forging.

[0067] The tether cable 304 may include one or more strands 701 extending longitudinally along or twisting around the central axis of the tether. For example, one or more strands 701 may extend around the central axis in a first helical direction 702, and one or more strands 701 may extend around the central axis in a second helical direction 1106. The first helical direction 702 may be, for example, clockwise around the central axis, and the second helical direction 1106 may be opposite to the first helical direction 702, for example, counterclockwise around the central axis.

[0068] refer to Figure 12 A cross-sectional view of a tethered cable according to one embodiment is shown. As described above, in some embodiments, misalignment of the connectors 306 can cause the tether assembly 214 to detach from the biostimulator 100. However, the threaded connector 1102 does not require alignment between the connectors 306, thus reducing the likelihood of such an event. However, the tether assembly 214 including the threaded connector 1102 may need to transmit torque. Thus, an alternative tethered cable 304 structure can be used.

[0069] In one embodiment, the tethered cable 304 includes a core strand 802 and a first plurality of strands 804 as described above. For example, the core strand 802 may extend longitudinally along a central axis, and the first plurality of strands 804 may be wound or twisted around the core strand 802 in a first helical direction 702. To further facilitate torque transmission, the tethered cable 304 may have a multi-layer structure including a second plurality of strands 1202 extending around the core strand 802 in a second helical direction 1106. The second plurality of strands 1202 may be radially positioned between the core strand 802 and the first plurality of strands 804. For example, the second plurality of strands 1202 may be wound around the core strand 802, and then the first plurality of strands 804 may be wound around the second plurality of strands 1202. Thus, in the multi-layer structure, the second plurality of strands 1202 may be the first layer of strands, and the first plurality of strands 804 may be the second layer of strands.

[0070] The illustrated structure with a core strand 802 and two winding layers is provided by way of example, and more or fewer winding layers can be used. For example, in one embodiment, a four-winding-layer structure is used. This structure can be a 1×5×8×12×16 strand construction, which refers to a single core strand 802, five strands in a first layer wound around the core strand 802 in a first direction, eight strands in a second layer wound around the first layer in a second direction, twelve strands in a third layer wound around the second layer in a third direction, and sixteen strands in a fourth layer wound around the third layer in a fourth direction. These layers can be wound in opposite directions relative to adjacent layers. For example, the five strands in the first layer and the twelve strands in the third layer can be wound clockwise, while the eight strands in the second layer can be wound counterclockwise.

[0071] A single flexible multi-strand tethered cable 304 can allow torsional capability in a first direction (e.g., clockwise) or a second direction (e.g., counterclockwise). In one embodiment, the torsional capability can be biased more in a particular direction based on the winding direction of the outer strands. For example, when the outer strands are wound clockwise (based on the right-hand rule) around the core strand 802, the tethered cable 304 has greater torsional capability in the clockwise direction than in the counterclockwise direction. This bias may be due to the outer strands tightening when torque is applied, resulting in a tighter composite strand that is more effectively torsioned. Similarly, when the outer strands are wound counterclockwise around the core strand 802, the tethered cable 304 can have greater torsional capability in the counterclockwise direction.

[0072] As described above, the first multiple strands 804 can be forged to provide a cylindrical outer surface and enhance the integrity of the cable structure. In an embodiment having four strand layers surrounding the core strands 802 (as described above), each filament of the cable structure can have the same filament diameter, for example, 0.0022 inches. The outer layers can then be forged to reduce the combined dimensions of the individual strands to a forged diameter of 0.019 inches.

[0073] refer to Figure 13 The diagram shows a cross-sectional view of an attachment feature of a biostimulator according to one embodiment. The attachment feature 102 of the biostimulator 100 may have a channel 520 for receiving a threaded connector 1102. As described above, the channel 520 of the attachment feature 102 may have a channel thread 1302 for receiving a threaded portion 1104 of the connector 306, rather than a stepped channel 520 with resistance to displacement. The channel thread 1302 may include a female thread that mates with a male thread of the threaded portion 1104 of the connector 306 to attach the biostimulator 100 to the biostimulator delivery system 101.

[0074] Reference Figure 14The image shows a side view of a threaded connector of a tether assembly for engaging an attachment feature of a biostimulator according to one embodiment. Engagement and disengagement of the biostimulator 100 can be achieved by rotating the tether cable 304 relative to the attachment feature 102. For example, when the threaded portion 1104 of the threaded connector 1102 has engaged the channel 520 of the attachment feature 102, the tether cable 304 can be twisted to screw the threaded portion 1104 into the channel thread 1302. Rotation of the tether cable 304 can be driven by a handle 202.

[0075] Reference Figure 15 A cross-sectional view of a biostimulator delivery system according to one embodiment is shown. The biostimulator delivery system 101 may include a torque shaft 1502. The torque shaft 1502 may extend from a handle 202 to a docking cap 210 through an elongated conduit 204. As described above, the handle 202 may include a first handle portion 212 and a second handle portion 216. The first handle portion 212 may be coupled to the torque shaft 1502 to transmit torque to the docking cap 210. Thus, rotation or reverse rotation of the attachment feature 102 may be provided by the first handle portion 212 when the attachment feature 102 is received within the docking cavity 308. Similarly, the second handle portion 216 may be coupled to a tethered cable 304 to transmit torque to a threaded connector 1102.

[0076] Similar to about Figure 10 The described tether assembly 214, Figure 15 The tether assembly 214 may include a support tube 1002 connected to the tether cable 304. The support tube 1002 extends from the handle 202 to the tube end 1004. More specifically, the support tube 1002 may be connected to a second handle portion 216 at its proximal end. Furthermore, the tether cable 304 may be connected to and extend from the tube end 1004 to the threaded connector 1102. Therefore, rotation of the second handle portion 216 can transmit torque to the threaded connector 1102 via the support tube 1002 and the tether cable 304. When the threaded connector 1102 engages with the channel thread 1302 and the mating cap 210 engages with the attachment feature 102, relative rotation between the first handle portion 212 and the second handle portion 216 can thus cause the threaded portion 1104 to screw into or out of the attachment feature 102. Therefore, similar to the dual-tether embodiment described above, the single-tether embodiment can reliably support the biostimulator 100 in tether mode and can be detached from the biostimulator 100 for implantation of the biostimulator 100 for pacing target anatomy.

[0077] In the foregoing description, the invention has been described with reference to specific exemplary embodiments thereof. It will be apparent that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. Therefore, the description and drawings should be considered illustrative rather than restrictive.

Claims

1. A biostimulator delivery system, comprising: handle; A slender tube extending from the handle; A docking cap rotatably connected to an elongated catheter, wherein the docking cap includes a docking cavity for receiving attachment features of a biostimulator; and A tether assembly extending from the handle through a slender conduit, wherein the tether assembly includes a connector fixedly mounted on the tether cable such that the connector is immovable relative to the tether cable, wherein the tether cable extends longitudinally through a central hole in the connector to a distal cable end, wherein the tether cable includes a core strand, a first plurality of strands extending around and wound around the core strand in a first helical direction between the proximal and distal cable ends, and a second plurality of strands extending radially around the core strand in a second helical direction opposite to the first helical direction between the core strand and the first plurality of strands.

2. The biostimulator delivery system according to claim 1, wherein, The core strands have a circular cross-sectional profile, and wherein the first plurality of strands have a non-circular cross-sectional profile.

3. The biostimulator delivery system according to claim 1, wherein, The connector has an annular cross-sectional profile, and the distal end of the connector is dome-shaped.

4. The biostimulator delivery system according to claim 1, wherein, The tether assembly includes a support tube extending from the handle to a tube end, wherein the tether cable is coupled to the tube end and extends from the tube end to the connector.

5. The biostimulator delivery system according to claim 4, wherein, The tether assembly includes a second connector at a second distal end of the second tether cable, wherein the tether assembly includes a second support tube extending from the handle to a second tube end, and wherein the second tether cable is coupled to the second tube end and extends from the second tube end to the second connector.

6. The biostimulator delivery system according to claim 1, wherein, The tether assembly includes a second connector and a retaining coil at a second distal end of the second tether cable, wherein the tether cable and the second tether cable extend through the cavity of the retaining coil such that the retaining coil restricts lateral movement of the tether cable relative to the second tether cable.

7. The biostimulator delivery system according to claim 1, wherein, The connector includes a threaded portion configured to be screwed into the attachment feature.

8. The biostimulator delivery system of claim 7, further comprising a torque shaft extending from the handle through the elongated conduit to the docking cap, wherein the handle includes a first handle portion coupled to the torque shaft to transmit torque to the docking cap, and wherein the handle includes a second handle portion coupled to the tether cable to transmit torque to the connector.

9. A biostimulator delivery system, comprising: handle; A slender tube extending from the handle; A docking cap rotatably connected to an elongated catheter, wherein the docking cap includes a docking cavity for receiving attachment features of a biostimulator; and A tether assembly extending from the handle through a slender conduit, wherein the tether assembly includes a first connector mounted on a first tether cable and a second connector mounted on a second tether cable, wherein the first tether cable extends longitudinally through a central hole in the connector to a distal cable end, the first connector being fixedly mounted on the first tether cable at the distal cable end such that the first connector is immovable relative to the first tether cable, wherein the first tether cable includes a core strand, a first plurality of strands extending around and wound around the core strand in a first helical direction between the proximal and distal cable ends, and a second plurality of strands extending radially around the core strand in a second helical direction opposite to the first helical direction between the core strand and the first plurality of strands.

10. The biostimulator delivery system according to claim 9, wherein, The tether assembly includes a first support tube extending from the handle to a first tube end and a second support tube extending from the handle to a second tube end, wherein the first tether cable is connected to the first tube end and extends from the first tube end to the first connector, and wherein the second tether cable is connected to the second tube end and extends from the second tube end to the second connector.

11. The biostimulator delivery system according to claim 10, wherein, The tether assembly includes a retaining coil, wherein the first tether cable and the second tether cable extend through the cavity of the retaining coil, such that the retaining coil restricts lateral movement of the first tether cable relative to the second tether cable.

12. The biostimulator delivery system according to claim 11, wherein, The inner cavity of the retaining coil has an inner diameter smaller than the combined cross-sectional size of the first support tube and the second support tube.

13. A biostimulator delivery system, comprising: handle; A slender tube extending from the handle; A docking cap rotatably connected to an elongated catheter, wherein the docking cap includes a docking cavity for receiving attachment features of a biostimulator; and A tether assembly extending from the handle through a slender conduit, wherein the tether assembly includes a threaded connector fixedly mounted on the distal cable end of the tether cable, and wherein the tether cable extends longitudinally through a central hole in the threaded connector, wherein the tether cable includes a core strand, a first plurality of strands extending around and wound around the core strand in a first helical direction between the proximal and distal cable ends, and a second plurality of strands extending radially around the core strand in a second helical direction opposite to the first helical direction between the core strand and the first plurality of strands.

14. The biostimulator delivery system according to claim 13, wherein, The tether assembly includes a support tube extending from the handle to a tube end, wherein the tether cable is coupled to the tube end and extends from the tube end to the threaded connector.

15. The biostimulator delivery system according to claim 13, wherein, The threaded connector includes a threaded portion configured to be screwed into the attachment feature.

16. The biostimulator delivery system of claim 13, further comprising a torque shaft extending from the handle through the elongated conduit to the docking cap, wherein the handle includes a first handle portion coupled to the torque shaft to transmit torque to the docking cap, and wherein the handle includes a second handle portion coupled to the tethered cable to transmit torque to the threaded connector.

Images