Biostimulator delivery system with solderless bearing holder

Abstract

A delivery system for delivering or retrieving a biological stimulator, such as a leadless cardiac pacemaker, is described. A biostimulator delivery system includes a docking cap supported by a bearing within a bearing housing. The bearing allows relative rotation between a torque shaft connected to the docking cap and an outer conduit connected to the bearing housing. The bearing housing and docking cap include respective bearing retainers that confine the bearing within the bearing housing without a weld attachment. The non-welding retainer of the biological stimulator delivery system provides firm mechanical fixation for the bearing, and is not easy to corrode. Other embodiments are also described and claimed.

Description

[0001] The present invention is a divisional application of the Chinese invention patent application (application number: 202080031820.0, application date: April 6, 2020, invention name: Biostimulator delivery system with weld-free bearing retainer).

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 843,126 filed on May 3, 2019 and U.S. Patent Application No. 16 / 838,865 filed on April 2, 2020, both of which are entitled "Biostimulator Transport System Having Weldless Bearing Retainer," which are incorporated herein by reference in their entirety to provide continuity of disclosure. Technical Field

[0003] The present disclosure relates to biostimulators and related delivery and retrieval systems and methods. More specifically, the present disclosure relates to delivery systems for delivering or retrieving leadless biostimulators. Background Art

[0004] Cardiac pacing by an artificial pacemaker provides electrical stimulation of the heart when the patient's own natural pacing and / or conduction system is unable to provide synchronized atrial and ventricular contractions at a rate and interval sufficient to ensure the patient's health. This anti-bradycardia pacing has provided symptom relief and even life support for thousands of patients. Cardiac pacing can also provide electrical overdrive stimulation to inhibit or convert tachyarrhythmias, again relieving symptoms and preventing or terminating arrhythmias that may lead to sudden cardiac death.

[0005] Cardiac pacing with currently available or conventional pacemakers is typically performed by a pulse generator implanted subcutaneously or submuscularly in or near the patient's chest area. The generator is typically connected to the proximal end of one or more implanted leads, which include one or more electrodes for positioning near the inner or outer wall of the heart chamber. Although more than 100,000 conventional cardiac pacing systems are implanted each year, there are various well-known difficulties, several of which are listed below. For example, when the pulse generator is located subcutaneously, skin ridges may occur, which may be unsightly, uncomfortable, or irritating to the patient, and the patient may subconsciously or compulsively manipulate or "twiddle" with it. Even without constant manipulation, subcutaneous pulse generators are subject to corrosion, extrusion, infection, disconnection, insulation damage, or conductor fractures at the lead. Although submuscular or abdominal placement can address some of these issues, such placement involves more difficult implantation and adjustments to the surgical procedure, which can prolong the patient's recovery time.

[0006] Leadless pacemakers incorporate electronic circuits at the pacing site and eliminate leads, thus avoiding the above-mentioned disadvantages of traditional cardiac pacing systems. Leadless pacemakers can be anchored at the pacing site by an anchor. During delivery or retrieval of the leadless pacemaker, the transmission system can apply torque to the leadless pacemaker through the docking cap to screw the anchor into or out of the target tissue. Summary of the invention

[0007] Existing delivery systems for delivering or retrieving leadless cardiac pacemakers can have a deflectable catheter, and a deflection mechanism of the deflectable catheter can apply stress to the attachment between a docking cap and the deflectable catheter. Such stress can cause mechanical failure of the delivery system, for example, at a bearing connecting the docking cap to the deflectable catheter. Existing ways of securing the bearing to the docking cap include welding, which is susceptible to corrosion and mechanical strength because the bearing and the docking cap are typically made of different materials. Therefore, a biostimulator delivery system would benefit from a mechanism for securing the bearing to the docking cap that is mechanically strong and reduces the potential for corrosion.

[0008] A biostimulator delivery system is provided, such as a catheter-based system for delivering or retrieving a leadless cardiac pacemaker, having a weldless bearing retention mechanism and a deflection mechanism contained within a bearing housing. In one embodiment, the biostimulator delivery system includes an outer catheter and a torque shaft extending through an inner lumen of the outer catheter. More specifically, the bearing housing is mounted at a distal end of the outer catheter and a docking cap is mounted at a distal end of the torque shaft. The docking cap can rotate relative to the bearing housing. The bearing is radially located between the bearing and the docking cap to support such rotation. For example, an outer wall of the bearing, such as an outer wall of an outer ball bearing race, can be opposite to the bearing housing, and an inner wall of the bearing, such as an inner wall of an inner ball bearing race, can be opposite to the docking cap.

[0009] The bearing housing may include an outer bearing retainer, the butt cap may include an inner bearing retainer, and the bearing retainers may be longitudinally located on opposite sides of the bearing to retain the bearing in the longitudinal direction. For example, the inner bearing retainer may have a distal retainer face opposite to the proximal bearing face of the bearing, and the outer bearing retainer may have a proximal retainer face opposite to the distal bearing face of the bearing. The retainer faces may interfere with the longitudinal movement of the retainer to hold the retainer in place without requiring welding between the bearing and the butt cap or the bearing housing.

[0010] In one embodiment, the internal bearing retainer includes an inner ring mounted on the neck of the docking cap, and the external bearing retainer includes an outer ring coupled to the distal flange of the bearing housing. The ring can provide a bearing retainer to constrain the bearing without being directly connected to the bearing. Thus, the biostimulator delivery system can include a weld-free bearing retainer to constrain the bearing that allows rotation between the torque shaft and the outer catheter. The bearing does not need to be welded to the docking cap or the bearing housing, and therefore, the bearing retention mechanism is mechanically strong and reduces the possibility of corrosion.

[0011] The above summary does not include an exhaustive list of all aspects of the invention. It is contemplated that the invention includes all devices, systems and methods that can be practiced from all suitable combinations of the various aspects summarized above and those disclosed in the detailed description below and specifically pointed out in the claims filed with this application. Such combinations have specific advantages not specifically enumerated in the above summary. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The novel features of the invention are particularly set forth in the claims that follow. A better understanding of the features and advantages of the invention will be obtained by reference to the following detailed description, which sets forth illustrative embodiments in which the principles of the invention are utilized, and the accompanying drawings, which are as follows:

[0013] Figure 1 is a schematic medial-lateral cross-section of a patient's heart illustrating an exemplary implantation of a biostimulator in the patient's heart according to an embodiment.

[0014] Figure 2A-2B 1 and 2 are side and end views, respectively, of a biostimulator according to an embodiment.

[0015] Figure 3 is a perspective view of a biostimulator delivery system according to one embodiment.

[0016] Figure 4 is a perspective view of a distal portion of a biostimulator retrieval system prior to connection to a biostimulator, according to an embodiment.

[0017] Figure 5 is a perspective view of a distal portion of a biostimulator delivery system prior to connection to a biostimulator according to an embodiment.

[0018] Figure 6 is a side view of a distal portion of a biostimulator retrieval system according to an embodiment.

[0019] Figure 7 According to an embodiment Figure 6 A cross-sectional view of the distal portion of the biostimulator retrieval system.

[0020] Figure 8 is a cross-sectional view of a bearing housing of a biostimulator retrieval system according to one embodiment.

[0021] Fig. 9 is a cross-sectional view of a docking cap assembly of a biostimulator retrieval system according to one embodiment.

[0022] Fig.10 is a side view of a distal portion of a biostimulator delivery system according to an embodiment.

[0023] Fig.11 According to an embodiment Fig.10 A cross-sectional view of the distal portion of a biostimulator delivery system. DETAILED DESCRIPTION

[0024] Embodiments describe a biostimulator delivery system, e.g., a catheter-based system for delivering or retrieving a leadless cardiac pacemaker having a weldless bearing retainer. The biostimulator can be used to pace cardiac tissue, as described below. However, the biostimulator can be used for other applications, such as deep brain stimulation, and thus, the reference to a cardiac pacemaker as a biostimulator is not limiting.

[0025] In various embodiments, description is made with reference to the accompanying drawings. However, certain embodiments may be implemented without one or more of these specific details, or in combination with other known methods and configurations. In the following description, many specific details, such as specific configurations, dimensions and processes, are set forth in order to provide a thorough understanding of the embodiments. In other cases, well-known processes and manufacturing techniques are not particularly described in detail to avoid unnecessary fuzziness of the description. References to "one embodiment", "embodiment", etc. throughout this specification mean that the specific features, structures, configurations or characteristics described are included in at least one embodiment. Therefore, the phrases "one embodiment", "embodiment", etc. that appear in different places throughout the specification do not necessarily refer to the same embodiment. In addition, in one or more embodiments, specific features, structures, configurations or characteristics may be combined in any suitable manner.

[0026] Throughout the description, the use of relative terms may indicate relative positions or directions. For example, "distal" may indicate a first direction along the longitudinal axis of the biostimulator delivery system. Similarly, "proximal" may indicate a second direction opposite to the first direction. However, such terms are provided to establish a relative frame of reference and are not intended to limit the use or orientation of the biostimulator delivery system to the specific configurations described in the various embodiments below.

[0027] In one aspect, a biostimulator delivery system is provided. The biostimulator delivery system includes a bearing radially located between a bearing housing and a docking cap, and the bearing is not secured to the bearing housing or the docking cap by welding. For example, the bearing can be axially located between the docking cap and a corresponding bearing retainer of the bearing housing. The weld-free securing of the bearing allows the bearing to provide support for relative rotation of the components without being susceptible to corrosion. In addition, the weld-free securing of the bearing can resist axial loads applied by a deflection mechanism contained in the bearing housing to provide a mechanically robust biostimulator delivery system.

[0028] refer to Figure 1 , a schematic mid-transverse cross-section of a patient's heart is shown, showing an exemplary implantation of a biostimulator in the patient's heart, according to one embodiment. A cardiac pacing system includes one or more biostimulators 100. The biostimulators 100 can be implanted in a patient's heart 104 and can be leadless and, therefore, can be leadless cardiac pacemakers 102. Each biostimulator 100 can be placed in a cardiac chamber, such as the right atrium and / or right ventricle of the patient's heart 104, or attached to the interior or exterior of a cardiac chamber. Attachment of the biostimulator 100 to cardiac tissue can be achieved by one or more fixation elements 106, such as helical anchors. In a particular embodiment, the leadless cardiac pacemaker 102 can use two or more electrodes located on or within the housing of the leadless cardiac pacemaker 102 for pacing the cardiac chamber upon receiving a trigger signal from an internal circuit and / or from at least one other device within the body.

[0029] refer to Figure 2A , shows a side view of a biostimulator according to one embodiment. The biostimulator 100 can be a leadless cardiac pacemaker 102 that can perform cardiac pacing and has many of the advantages of conventional cardiac pacemakers while expanding performance, functionality, and operating characteristics. The biostimulator 100 can have two or more electrodes, for example, a distal electrode 202 and a proximal electrode 204 located within, on, or near a housing 206 of the biostimulator 100. In one embodiment, one or more fixation elements 106 form part of the distal electrode 202. The electrode can deliver pacing pulses to the muscle of the heart chamber and, optionally, can sense electrical activity from the muscle. The electrode can also communicate bidirectionally with at least one other device inside or outside the body.

[0030] In one embodiment, the housing 206 has a longitudinal axis 208, and the distal electrode 202 can be a distal pacing electrode mounted on the housing 206 along the longitudinal axis 208. The housing 206 can include a main battery to provide power for pacing, sensing, and communication, which can include, for example, bidirectional communication. The housing 206 can optionally include an electronics compartment 210 to hold circuits suitable for different functions. For example, the electronics compartment 210 can include circuits for sensing cardiac activity from the electrodes, circuits for receiving information from at least one other device via the electrodes, circuits for generating pacing pulses delivered via the electrodes, or other circuits. The electronics compartment 210 can include circuits for transmitting information to at least one other device via the electrodes, and can optionally include circuits for monitoring device health. The circuitry of the biostimulator 100 can control these operations in a predetermined manner. In some embodiments of the cardiac pacing system, cardiac pacing is provided without a pulse generator located in the chest area or abdomen, without electrode leads separate from the pulse generator, without a communication coil or antenna, and without requiring additional battery power for transmitting communications.

[0031] The leadless pacemaker or other leadless biostimulator 100 can be secured to an intracardiac implantation site by one or more active engagement mechanisms or fixation mechanisms, such as a screw or helical member screwed into the myocardium. In one embodiment, the biostimulator 100 includes a fixation element 106 coupled to a housing 206. The fixation element 106 can be a helical element to screw into the target tissue. More specifically, the fixation element 106 can extend helically from a flange 214 of the biostimulator 100 mounted on the housing 206 to a distal end at a helical distal end 216.

[0032] refer to Figure 2B , shows an end view of a biostimulator according to one embodiment. The helical distal end 216 can be located distal to the distal electrode 202 (the electrode located in the center). Thus, when the biostimulator 100 contacts the target tissue, the distal tip can pierce the tissue and the housing 206 can be rotated to screw the external fixation element 106 into the target tissue, thereby pulling the distal electrode 202 into contact with the tissue.

[0033] As described below, a leadless pacemaker or other leadless biostimulator 100 can be delivered to or retrieved from a patient using a delivery system. In some embodiments, the delivery system is a delivery system for delivering the leadless pacemaker to a target tissue. In some embodiments, the delivery system is a retrieval system for retrieving the leadless pacemaker from a target tissue.

[0034] refer to Figure 3, shows a perspective view of a biostimulator delivery system according to one embodiment. The biostimulator delivery system 300 can be used to deliver a biostimulator 100 (e.g., a leadless cardiac pacemaker 102) to or remove from a patient. The biostimulator delivery system 300 can include an elongated catheter 302 extending from a handle 304 to a distal end 306. The elongated catheter 302 can be a deflectable catheter, and an operator can use the handle 304 to manipulate the distal end 306 within the patient. In an embodiment, the biostimulator delivery system 300 includes a guide catheter 308 mounted on the elongated catheter 302. The guide catheter 308 can be slidably disposed on the elongated catheter 302 such that a distal portion of the guide catheter 308 can slide distally over the biostimulator 100 and / or the distal end 306 of the elongated catheter 302. Similarly, the biostimulator delivery system 300 can include an introducer hub assembly 310 mounted on the guide catheter 308. The introducer hub assembly 310 can be slidably disposed on the guide catheter 308 such that the distal portion of the introducer hub assembly 310 can slide distally over the distal end 306 of the elongated catheter 302 and / or the distal portion of the guide catheter 308. More specifically, the introducer hub assembly 310 can be inserted into an interventional sheath to gain access to the patient's vasculature, and after the intervention is established, the distal portion of the guide catheter 308 and / or the distal end 306 of the elongated catheter 302 can be advanced through the interventional sheath into the patient's body.

[0035] The distal end 306 of the elongated catheter 302 can be selectively connected to the biostimulator 100. More specifically, the biostimulator 100 can be mounted on the distal end 306 of the elongated catheter 302. During delivery and / or removal of the biostimulator 100 from the patient, the biostimulator 100 can be protected by the protective pacemaker sheath of the distal portion of the guide catheter 308. Thus, the biostimulator 100 can be advanced into the patient together with the distal end 306.

[0036] The leadless pacemaker system can be used to implant one or more biostimulators 100 in the atria and / or ventricles of a patient's heart 104. Implantation of each biostimulator 100 can be achieved in part by endocardial insertion of the biostimulator 100. For example, the elongated catheter 302 of the leadless pacemaker system can include a torque shaft that is twistable and can be used to rotate the biostimulator 100 in a first direction, such as a clockwise direction. When the fixation element 106 is in contact with the cardiac tissue, rotating the biostimulator 100 can cause the fixation element 106 to screw into the cardiac tissue and secure the biostimulator 100 to the cardiac tissue. Similarly, removal and retrieval of the biostimulator 100 can be accomplished endocardially. For example, the torque shaft of the elongated catheter 302 can be rotated in a second direction, such as counterclockwise, to disengage the biostimulator 100 from the cardiac tissue. Thus, having a configuration similar to Figure 3 The delivery and retrieval system of the illustrated configuration may be used to deliver and / or retrieve the biostimulator 100 from the target anatomy.

[0037] Reference Figure 4 , shows a perspective view of a distal portion of a biostimulator retrieval system prior to attachment to a biostimulator, according to one embodiment. This view is for retrieving a leadless pacemaker Figure 3 A close-up view of one embodiment of a distal portion of a biostimulator delivery system 300 is shown. Accordingly, a retrieval system can include features for engaging the leadless cardiac pacemaker 102 to facilitate capture and unscrewing of the biostimulator 100 from target tissue.

[0038] The distal portion of the retrieval catheter may include a snare 402 configured to grasp the biostimulator 100 or other medical device. The snare 402 may include at least one loop 403, such as a wire loop, extending from the elongated catheter 302. As the snare 402 is advanced distally from the docking cap 404 and out of the biostimulator delivery system 300, the size of the loop 403 may expand to assist the user in positioning the snare 402 around or near the biostimulator 100 to be retrieved. In some embodiments, such as Figure 4 As shown, the loop set 402 may include a plurality of loops 403, such as three loops. However, any number of loops 403 may be used, as long as the elongated catheter 302 includes sufficient volume to accommodate the loops.

[0039] The distal portion of the retrieval catheter may include a docking cap 404 and a bearing housing 405, wherein the docking cap 404 is configured to allow the leadless cardiac pacemaker 102 to dock with the biostimulator delivery system 300 after the pacemaker is engaged with the loop kit 402, and the bearing housing 405 includes a bearing to support the docking cap 404 and allow the docking cap 404 and the bearing housing 405 to rotate relative to each other during torque transmission. More specifically, the bearing housing 405 can be mounted on an outer catheter 406 of the elongated catheter 302, and the docking cap 404 can be mounted on a torque shaft (hidden within the outer catheter 406) of the elongated catheter 302. A user can transmit torque through the torque shaft via handle control to rotate the docking cap 404 relative to the bearing housing 405. More specifically, the torque shaft can extend through the length of the catheter to a torque knob on the handle 304, or another rotatable portion of the handle 304, which is coupled to the torque shaft. Rotation or actuation of the torque knob rotates the torque shaft, thereby rotating the docking cap 404 at the end of the retrieval catheter. In some embodiments, the docking cap 404 can include a keyed portion or interference feature to apply additional torque to the pacemaker when rotating the biostimulator 100. A protective sheath 408 of the guide catheter 308 can be positioned along the outer catheter 406 and can be advanced or retracted to cover or expose the docking cap 404 and the leadless pacemaker.

[0040] During retrieval, the biostimulator delivery system 300 can be navigated through the patient's body to the implant site. The loop kit 402 can be placed over a retrieval feature, such as a handle 304 or hook feature on the biostimulator 100, and the loop 403 of the loop kit 402 can be reduced in size to catch or lock onto the retrieval feature of the pacemaker. After the loop kit 402 is captured and locked with the leadless pacemaker, the biostimulator 100 can be docked within the docking cap 404. More specifically, the attachment feature of the biostimulator 100 can be pulled into the docking cavity of the docking cap 404. In some embodiments, the docking cap 404 can include a key or interference feature that is configured to mate and engage with a corresponding key or feature on the pacemaker. In some embodiments, the key or slot on the docking cap 404 can match the unique shape or feature of the retrieval feature of the pacemaker. Because the key or slot on or in the docking cap 404 can mate and engage with the key or slot on the pacemaker, the retrieval catheter can be configured to apply torque to the pacemaker to unscrew and remove the pacemaker from the tissue.

[0041] Reference Figure 5 , shows a perspective view of a distal portion of a biostimulator delivery system prior to attachment to a biostimulator according to an embodiment. This view is for delivering a leadless pacemaker Figure 3A close-up view of one embodiment of a distal portion of a biostimulator delivery system 300 is shown. Thus, the delivery system can include features that engage a leadless pacemaker to allow the biostimulator 100 to be screwed into the target tissue.

[0042] Similar to the retrieval system, the delivery system can include a docking cap 404 having a key configured to engage the leadless pacemaker and apply torque to screw the fixation element 106 into the target tissue. The delivery system can also include an elongated catheter 302 having a torque shaft for mounting the docking cap 404 and an outer catheter 406 having a bearing housing 405 mounted thereon. A protective sheath 408 of the guide catheter 308 can be positioned along the outer catheter 406 and can be advanced or retracted to cover or expose the docking cap 404 and the leadless pacemaker.

[0043] In one embodiment, the delivery system includes tethers 502a, 502b configured to engage docking features on the biostimulator 100. The tether 502 may include a wire, shaft, tube, cable, rope, string, or other similar structure that can extend through the elongated catheter 302. In some embodiments, the tether 502 includes a shape memory material, such as nitinol. In other embodiments, the tether 502 includes a stainless steel wire or braid.

[0044] Delivery of the biostimulator 100 may be accomplished by tethering the biostimulator 100 to the biostimulator delivery system 300. The tether 502 may include a distal feature, e.g., a feature on the tether 502 that protrudes radially from the tether 502, such as a bump, sphere, cylinder, cuboid, or other similar shape extending outward from the tether 502. Typically, the cross-sectional diameter of the distal feature is greater than the cross-sectional diameter of the tether 502. In one embodiment, the distal feature on the tether 502a may be further forward relative to the catheter than the distal feature on the tether 502b, such that when the tethers 502 are pushed together, the distal feature on the tether 502b abuts against the tether 502a. This makes the combined cross-sectional size of the distal feature and the tether 502 smaller than if the distal features were arranged side by side.

[0045] When the tether 502 and the distal features are in an unaligned configuration, the cross-sectional diameter of the distal features is reduced because the distal features are not positioned side by side. The tether distal features can then be advanced through the hole of the attachment feature of the leadless pacemaker (not shown) in this unaligned configuration. In such an embodiment, the diameter of the hole can be large enough to allow the distal features of the tether 502 to pass through when in an unaligned configuration. When the distal features pass through the hole, the length of the tether 502 can then be adjusted to align the distal features into a side-by-side configuration. When the distal features are positioned side by side, the combined cross-sectional diameter of the distal features becomes larger than the diameter of the hole, which essentially locks the tether and the distal features in the attachment feature and prevents the distal features from being able to pass through the hole proximally.

[0046] When the tether 502 is locked to the biostimulator 100, the tether 502 can be retracted to dock the biostimulator 100 to the docking cap 404. More specifically, the attachment feature of the biostimulator 100 can be pulled into the docking cavity of the docking cap 404. The docking cap 404 of the delivery system can include a torque slot (not shown) that is sized and configured to match the attachment feature of the biostimulator 100, which is disposed on the proximal end of the pacemaker. It should be understood that the attachment feature and the torque slot can include any number of shapes, such as square, rectangular, triangular, pentagonal, hexagonal, cross, "X" shape, etc., as long as the attachment feature fits the torque slot and can have a rotational torque applied thereto by the torque slot. When the distal end 306 of the biostimulator delivery system 300 passes through the patient to the delivery site, the torque slot can be rotated by rotation of a torque shaft that extends along the length of the elongated catheter 302 and enters the handle 304 (not shown). Thus, the biostimulator 100 may be threaded into the cardiac tissue at the delivery site.The tether 502 may be de-aligned to release the biostimulator 100 from the biostimulator delivery system 300 at the delivery site.

[0047] Having generally discussed the biostimulator delivery system, the distal portion of the biostimulator delivery system 300 will now be described in more detail with respect to the retrieval system and the delivery system. It should be understood that the features described with respect to one type of delivery system, e.g. Figure 6-9 The retrieval system shown, may be incorporated into another type of delivery system, e.g. Figure 10-11 The delivery system shown.

[0048] refer to Figure 6, shows a side view of a distal portion of a biostimulator retrieval system according to one embodiment. The biostimulator delivery system 300 for retrieving a leadless cardiac pacemaker 102 includes a bearing housing 405 mounted on an outer catheter 406. The bearing housing 405 has an outer surface surrounding components contained within the housing 206, such as bearings as described below. The bearings interconnect the bearing housing 405 with the docking cap 404. More specifically, a neck of the docking cap 404 is interconnected with the bearing housing 405, as described below, and the bearings allow the docking cap 404 to rotate relative to the bearing housing 405 about a central axis 620.

[0049] The docking cap 404 can include a distal cup 602 extending distally from the bearing housing 405. The distal cup 602 can include a docking cavity 606, which can be a generally cylindrical space within the distal cup 602. The docking cavity 606 can be sized and configured to accommodate an attachment feature of the biostimulator 100. In addition, as described above, a torque key feature 610 can be located within the docking cavity 606 to engage the attachment feature and transfer torque to the biostimulator 100. In an embodiment, a base 610 of the docking cap 404 extends between the distal cup 602 and the bearing housing 405, and torque is transferred to the distal cup 602 through the base 604.

[0050] Reference Figure 7 According to one embodiment, Figure 6 4. A cross-sectional view of a distal portion of a biostimulator retrieval system of FIG. The distal portion may include a torque shaft assembly 700 of the biostimulator delivery system 300. The torque shaft assembly 700 may include a torque shaft 702 connected to a docking cap 404, and a bearing 704 interconnecting the docking cap 404 to a bearing housing 405. As described below, the torque shaft assembly 700 may also include a pull ring assembly to apply a deflection load to the outer catheter 406 through the bearing housing 405. In one embodiment, the connection between the bearing 704, the docking cap 404, and the bearing housing 405 is weld-free. More specifically, the bearing housing 405 and the docking cap 404 may hold the bearing 704 without a welded joint. Eliminating the bearing weld may enhance the mechanical properties of the bearing 704, reduce the weld failure rate of the delivery system, and enhance the corrosion performance of the metal components of the distal portion.

[0051] In one embodiment, the outer catheter 406 of the delivery system extends from the handle 304 to the distal catheter end 706 along the central axis 620. More specifically, the outer catheter 406 has an inner cavity 708, which extends from the proximal catheter end to the distal catheter end 706 along the central axis 620. The inner cavity 708 provides a passage, and the torque shaft 702 is disposed in the passage. More specifically, the torque shaft 702 extends from the handle 304 to the distal shaft end 710 through the inner cavity 708. The distal shaft end 710 can be located distal to the distal catheter end 706. Therefore, the torque shaft 702 can be connected to the docking cap 404 at a position that is distal to the position where the outer catheter 406 is connected to the bearing housing 405.

[0052] In one embodiment, the bearing housing 405 is mounted on the distal catheter end 706. For example, the bearing housing 405 may include a proximal recess 712 to receive the distal catheter end 706 of the outer catheter 406. The proximal recess 712 may extend distally into the proximal side of the bearing housing 405. The proximal recess 712 may extend to a depth that allows a length of the outer catheter 406 to be located radially inward from the recess wall 714 (which defines the lateral boundary of the proximal recess 712) inside the bearing housing 405. In one embodiment, the recess wall 714 is a tapered wall having a proximal dimension (e.g., a cross-sectional diameter at the most proximal position) that is greater than a distal dimension (e.g., a cross-sectional diameter at the most distal position). The tapered recess and the proximal end of the bearing housing 405 provide a cavity for accommodating an adhesive. The adhesive may form a joint 770 to connect the bearing housing 405 to the outer catheter 406. In one embodiment, the adhesive is a light-activated adhesive, such as an ultraviolet light-activated adhesive. As described below, the bearing housing 405 can be formed of an opaque metal, and thus, the tapered recess allows sufficient light to penetrate axially into the adhesive joint 770 to illuminate and cure the adhesive within the proximal recess 712. Thus, the tapered recess allows an effective attachment to be formed between the distal catheter end 706 and the bearing housing 405.

[0053] The docking cap 404 of the biostimulator delivery system 300 can be mounted on the distal shaft end 710 of the torque shaft 702. For example, the docking cap 404 can include a neck 720 extending proximally from the base 604, and the distal shaft end 710 can be inserted into the central lumen of the neck 720. More specifically, the neck 720 can be a tubular extension extending from the base 604, and the torque shaft 702 can be accommodated in the central lumen of the tubular extension. In one embodiment, the central lumen can extend completely through the neck 720 and the base 604 into the docking cavity 606. Therefore, the lumen of the torque shaft 702 can be aligned with the central lumen of the docking cap 404 to allow the loop set 402 (not shown) to pass through the docking cap 404 from the torque shaft 702 toward the biostimulator 100 during retrieval.

[0054] The torque shaft 702 can be attached to the docking cap 404. For example, a bond or heat weld can be formed between the neck 720 and the outer surface of the torque shaft 702. The docking cap 404 and the torque shaft 702 can be formed of the same material, such as stainless steel, so that the heat weld can firmly fix the torque shaft 702 to the docking cap 404 to allow the torque applied to the handle 304 to be transmitted to the docking cap 404 through the torque shaft 702. The docking cap 404 can in turn transmit torque to the biostimulator 100 to unscrew the fixation element 106 from the target tissue.

[0055] The bearing 704 can support the butt cap 404 relative to the bearing housing 405. The bearing 704 can be radially located between the bearing housing 405 and the butt cap 404, and can concentrically hold the neck 720 of the butt cap 404 relative to the inner surface of the bearing housing 405. The bearing 704 allows the butt cap 404 to rotate freely relative to the bearing housing 405. The bearing 704 can be any of several types of bearings that allow the butt cap 404 to rotate radially. For example, the bearing 704 can be a sliding bearing, such as a bushing formed of a smooth material, such as polytetrafluoroethylene (PTFE). Alternatively, the bearing 704 can be a rolling element bearing, a jewel bearing, etc. In one embodiment, the bearing 704 is a ball bearing having an inner ring 722, an outer ring 724, and a plurality of balls 726 located between the inner ring 722 and the outer ring 724 to allow the rings to rotate freely relative to each other. The bearing 704 can be a roller bearing having a plurality of rollers. In any case, the bearing 704 can have an inner wall 728 , such as an inner surface of the inner race 722 opposite the neck 720 of the docking cap 404 , and an outer wall 730 , such as an outer surface of the outer race 724 opposite the inner surface of the bearing housing 405 .

[0056] The bearing 704 can be retained on the docking cap 404 and within the bearing housing 405 without the use of welding. It should be understood that any weld between the bearing 704 and the docking cap 404 or the bearing housing 405 may be susceptible to rupture under the load applied during delivery or retrieval of the biostimulator 100. The weld strength problem may be particularly severe in the case of welding between dissimilar metals. Assuming that the bearing 704 can be formed of a material different from the docking cap 404 or the bearing housing 405, it follows that any weld between them may have unreliable joint strength. In addition, welds between different materials are prone to corrosion, and welds can cause one or more rings of the bearing 704 to warp, which may result in reduced bearing function due to the heat-affected zone formed during welding. For all of these reasons, the torque shaft assembly 700 as described herein may include a bearing 704 that is not attached to the docking cap 404 or the bearing housing 405.

[0057] The biostimulator delivery system 300 can include a bearing 704 nested between a retainer of the docking cap 404 and a bearing housing 405. By nesting the bearing 704 between the retainers, the bearing 704 can be fixed in place without the need for an attachment joint, such as a weld. Thus, the retainer of the biostimulator delivery system 300 can be weld-free. In one embodiment, the bearing 704 is axially located between an outer bearing retainer 740 of the bearing housing 405 and an inner bearing retainer 742 of the docking cap 404. For example, the inner bearing retainer 742 can have a distal retainer face 750 opposite a proximal bearing face 752 of the bearing 704, and similarly, the outer bearing retainer 740 can have a proximal retainer face 754 opposite a distal bearing face 756. The opposing faces can be in sliding contact with each other to prevent axial movement of the bearing 704 while allowing the bearing 704 to be slidably mounted on the docking cap 404 and the bearing housing 405. More specifically, the inner wall 728 of the bearing 704 can be slidably mounted on the docking cap 404 and located distally of the internal bearing retainer 742, and the outer wall 730 of the bearing 704 can be slidably mounted in the bearing housing 405 and located proximal to the external bearing retainer 740.

[0058] The grooves in the bearing housing 405 and the docking cap 404 that retain the outer race 724 and the inner race 722 of the bearing 704 can be formed in a variety of ways. For example, the outer bearing retainer 740 and the inner bearing retainer 742 can be separate components attached to the docking cap 404 or the bearing housing 405, as described below with reference to Figure 8-9 As described. Optionally, the bearing retainer can be formed by deforming the docking cap 404 or the bearing housing 405. For example, the proximal end of the neck 720 can be flared outward to form an internal bearing retainer 742, or the distal end of the bearing housing 405 can be curled, swaged or bent inward to form an external bearing retainer 740. In any case, an outer groove can be provided on the inner surface of the bearing housing 405 to retain the outer wall 730 of the bearing 704, and an inner groove can be provided on the outer surface of the docking cap 404 to retain the inner wall 728 of the bearing 704. Therefore, the groove can have corresponding distal and proximal retainer faces opposite to the bearing surface. In this way, the outer groove matches the outer portion of the bearing 704, and the inner groove matches the inner portion of the bearing 704 to retain the bearing 704 without welding, which would otherwise impair the strength or function of the bearing 704.

[0059] In one embodiment, the torque shaft assembly 700 includes a deflection mechanism that allows a user to laterally deflect the elongated catheter 302 using the handle 304 of the biostimulator delivery system 300. The deflection mechanism can include a pull wire 760 that extends from the handle 304 through the lumen 708 into the bearing housing 405. The pull wire 760 can extend axially through the lumen 708 between the outer catheter 406 and the torque shaft 702. Thus, an axial load applied to the proximal end of the pull wire 760 at the handle 304 can cause the distal end of the pull wire 760 to move within the bearing housing 405. The deflection mechanism can also include a pull ring 762 that is contained within the bearing housing 405, axially between the distal catheter end 706 and the bearing 704. The pull ring 762 can be connected to the pull wire 760. For example, the distal end of the pull wire 760 can be connected (e.g., welded) to the pull ring 762 via a joint 772. Thus, an axial load applied to the pull wire 760 by the handle 304 causes the pull ring 762 to move within the bearing housing 405 .

[0060] Accommodating the pull ring 762 within the bearing housing 405 provides a simple design that effectively transmits axial loads to the bearing housing 405 through the pull wire 760. For example, the proximal surface of the pull ring 762 can abut against a boss 761 on the inner surface of the bearing housing 405. More specifically, an interference fit can be provided between the pull ring 762 and the boss 761. The interference fit allows the pull ring 762 to apply a load to the bearing retainer without the need for welding. The weld-free connection between the pull ring 762 and the bearing housing 405 allows the pull ring 762 and the bearing housing 405 to be formed of different materials without the risk of corrosion of the components. When the pull wire 760 is pulled, the proximal surface of the pull ring 762 can be pressed against the boss 761. The pull wire 760 can be laterally offset from the central axis 620 of the elongated catheter 302. Therefore, the pulling force can be applied eccentrically to the boss 761, causing the bearing housing 405 to deflect preferentially in one direction, causing the outer catheter 406 to bend laterally in that direction.

[0061] Reference Figure 8 , shows a cross-sectional view of a bearing housing of a biostimulator retrieval system according to an embodiment. The bearing housing 405 can incorporate the bearing 704 and the pull ring 762 in an interior region, such as a distal recess 806 distal to the boss 761. In contrast, the proximal recess 712 can be proximal to the boss 761 and can include the distal catheter end 706 of the outer catheter 406. The distal recess 806 and the proximal recess 712 can be connected by a hole passing through the boss 761 in the longitudinal direction. The hole can receive the torque shaft 702 and the pull wire 760.

[0062] In one embodiment, the bearing housing 405 has a one-piece design. The one-piece design of the bearing housing 405 does not require a bonded joint, which has been shown to be susceptible to mechanical failure in two-piece bearing housing designs. More specifically, the one-piece design of the bearing housing 405 can have a solid and continuous sidewall extending from the proximal housing end 802 to the distal housing end 804. The sidewall can surround an internal cavity including a proximal recess 712 and a distal recess 806. The internal cavity can extend longitudinally from a proximal entrance at the proximal recess 712 to a distal entrance at the external bearing retainer 740. The bearing housing 405 can be machined from a metal billet, such as a stainless steel billet, to provide a Figure 8 The internal and external geometries shown. For example, the internal cavity can have an inner surface distal to the boss 761 (which provides a sliding fit with the pull ring 762), and an inner surface proximal to the external bearing retainer 740 (which provides a groove to accommodate the bearing 704). The bearing housing 405 can alternatively be molded, cast, or otherwise formed to have a one-piece design.

[0063] The groove for accommodating the outer portion of the bearing 704 can be formed by a combination of components. For example, the bearing housing 405 can include a distal flange 808 extending around the outer wall 730 of the bearing 704, near the distal housing end 804. The external bearing retainer 740 can include an external ring 810 coupled to the distal flange 808 to form a groove for accommodating the bearing 704. In one embodiment, the external ring 810 is a ring or annular disk formed of the same material as the bearing housing 405 (e.g., stainless steel). The external ring 810 can have an inner diameter around the distal entrance of the distal recess 806 that is smaller than the inner diameter of the distal flange 808. The external ring 810 can be welded to the distal flange 808 to provide a lip that is distal to the recess that accommodates the retainer. When the bearing 704 is positioned radially inward from the distal flange 808, the lip is distal to the bearing 704 and prevents the bearing 704 from moving distally. Thus, the lip can have a proximal retainer surface 754.

[0064] The distal flange 808 may include a cylindrical edge that guides and retains the bearing 704. The bearing housing 405 may have a step near the distal flange 808 against which the proximal bearing surface 752 abuts. More specifically, the step may include a distal retainer surface 750 opposite the bearing 704. The step in the inner surface of the bearing housing 405 may prevent the bearing 704 from moving proximally. Thus, the outer ring 810 and the step of the bearing housing 405 provide a weld-free retainer to hold the bearing 704 (e.g., outer race 724) in place.

[0065] Reference Fig. 9, a cross-sectional view of a docking cap assembly of a biostimulator retrieval system according to an embodiment is shown. The docking cap assembly 900 includes a docking cap 404 and a bearing 704. More specifically, the bearing 704 is slidably mounted on the docking cap 404 and retained between the base 604 of the docking cap 404 and the internal bearing retainer 742. As described above, the internal bearing retainer 742 can be integrally formed with the docking cap 404, for example, by radially flaring the neck 720 of the docking cap 404 outward to provide a retaining groove. However, in one embodiment, the retaining groove can be formed by a combination of components.

[0066] The internal bearing retainer 742 of the biostimulator delivery system 300 may include an inner ring 902 mounted on the neck 720 of the docking cap 404. Like the outer ring 810, the inner ring 902 may include a ring or annular disk welded to the proximal end of the neck 720. The inner ring 902 and the neck 720 may be formed of the same material. Therefore, when the inner ring 902 is welded to the neck 720, a strong weld may be formed. The strength of the weld joint between the inner ring 902 and the docking cap 404 may be assessed based on a comparison with the weld between the bearing 704 and the docking cap 404. As described above, the bearing ring and the neck 720 are typically formed of different materials, and therefore, the weld between the bearing 704 and the docking cap 404 is weaker than the weld between the inner ring 902 and the neck 720. Therefore, the retention strength of the docking cap 404 having a retaining groove may be significantly increased compared to the weld between the bearing ring and the docking cap 404. The retaining groove formed between the inner ring 902 and the base 604 of the docking cap 404 provides a weld-free retainer to hold the bearing 704 (eg, the inner race 722) in place.

[0067] refer to Fig.10 and 11 , various views of a distal portion of a biostimulator delivery system are shown according to one embodiment. The biostimulator delivery system is another type of biostimulator delivery system 300 described above. Certain features may differ between alternative types of biostimulator delivery systems 300. For example, referring to Figure 10-11 , the biostimulator delivery system may include a tether 502 having distal features to engage the attachment features of the biostimulator 100, as described above. The tether 502 may extend axially from the handle 304 through the central lumen of the torque shaft 702 and into the surrounding environment distal to the docking cap 404. However, many features of the alternative type of biostimulator delivery system 300 may be the same. For example, the above description of Figure 6-9 Features of the biostimulator retrieval system can be similarly incorporated into Figure 10-11 For simplicity, similar features are represented by Figure 10-11 It should be understood that the above Figure 6-9 The description provided also applies to Figure 10-11 Thus, these features may be claimed as part of a biostimulator retrieval system or a biostimulator delivery system, each of which is a type of biostimulator delivery system 300 .

[0068] In the following paragraphs, several embodiments are described by way of overview and not limitation.

[0069] In one embodiment, a biostimulator delivery system includes an outer catheter, a torque shaft, a bearing housing, a docking cap, and a bearing. The outer catheter has a distal catheter end and an inner cavity. The torque shaft extends through the inner cavity to a distal shaft end located distal to the distal catheter end. The bearing housing is mounted at the distal catheter end. The bearing housing includes an external bearing retainer. The docking cap is mounted at the distal shaft end. The docking cap includes an internal bearing retainer. The bearing is radially located between the bearing housing and the docking cap. The bearing includes an outer wall located proximal to the external bearing retainer and an inner wall located distal to the internal bearing retainer.

[0070] In this embodiment, the torque shaft is attached to the docking cap.

[0071] In this embodiment, the inner bearing retainer has a distal retainer face opposite the proximal bearing face of the bearing.

[0072] In this embodiment, the internal bearing retainer comprises an internal ring mounted on the neck of the docking cap.

[0073] In this embodiment, the inner ring and the neck are made of the same material. The inner ring is welded to the neck.

[0074] In this embodiment, the bearing housing includes a distal flange extending around an outer wall of the bearing. The outer bearing retainer includes an outer ring connected to the distal flange distal to the bearing.

[0075] In this embodiment, the biostimulator delivery system further comprises a pull wire extending radially through the lumen between the outer catheter and the torque shaft. The biostimulator delivery system further comprises a pull ring connected to the pull wire. The pull ring is axially contained within the bearing housing between the distal catheter end and the bearing.

[0076] In this embodiment, the bearing is not attached to the docking cap.

[0077] In this embodiment, the bearing includes an inner ring having an inner wall, an outer ring having an outer wall, and several balls between the inner ring and the outer ring.

[0078] In this embodiment, the bearing housing includes a proximal recess that receives the distal catheter end. The proximal recess includes a tapered wall.

[0079] In one embodiment, a torque shaft assembly includes a torque shaft, a docking cap, and a bearing. The torque shaft has a distal shaft end. The docking cap is mounted on the distal shaft end. The docking cap includes an internal bearing retainer. The bearing has an inner wall that is slidably mounted on the docking cap distal to the internal bearing retainer.

[0080] In this embodiment, the torque shaft is attached to the docking cap.

[0081] In this embodiment, the inner bearing retainer has a distal retainer face opposite the proximal bearing face of the bearing.

[0082] In this embodiment, the internal bearing retainer comprises an internal ring mounted on the neck of the docking cap.

[0083] In this embodiment, the inner ring and the neck are made of the same material. The inner ring is welded to the neck.

[0084] In one embodiment, a docking cap assembly includes a docking cap and a bearing. The docking cap includes an internal bearing retainer. The bearing has an inner wall that is slidably mounted on the docking cap at a distal side of the internal bearing retainer.

[0085] In this embodiment, the inner bearing retainer has a distal retainer face opposite the proximal bearing face of the bearing.

[0086] In this embodiment, the internal bearing retainer comprises an internal ring mounted on the neck of the docking cap.

[0087] In this embodiment, the inner ring and the neck are made of the same material. The inner ring is welded to the neck.

[0088] In this embodiment, the bearing includes an inner ring having an inner wall, an outer ring, and several balls between the inner ring and the outer ring.

[0089] In the foregoing description, the present invention has been described with reference to specific exemplary embodiments of the present invention. It will be apparent that various modifications may be made thereto without departing from the broader spirit and scope of the present invention as set forth in the appended claims. Therefore, the description and drawings are to be regarded as illustrative rather than restrictive.

Claims

1. A shaft assembly comprising: an outer catheter having a distal catheter end and an inner lumen; a bearing housing mounted on the distal catheter end; an inner shaft extending through the inner cavity to a distal shaft end; a docking cap mounted on the distal shaft end, wherein the docking cap is coupled to the bearing housing and has a docking cavity to receive an attachment feature of a biostimulator; as well as A pull wire extends through the lumen between the outer catheter and the inner shaft into the bearing housing such that an axial load applied to the proximal end of the pull wire causes the distal end of the pull wire to move within the bearing housing.

2. The shaft assembly of claim 1, wherein the inner shaft comprises a torque shaft, and the docking cap is coupled to the bearing housing via a bearing.

3. The shaft assembly of claim 2, further comprising a pull ring housed within the bearing housing, wherein the pull wire is coupled to the pull ring such that an axial load applied to the pull wire causes the pull ring to move.

4. The shaft assembly of claim 3, wherein the pull ring is axially located between the distal catheter end and the bearing.

5. The shaft assembly of claim 3, wherein a proximal surface of the pull ring abuts against an inner surface of the bearing housing.

6. The shaft assembly of claim 3, wherein the pull ring and the bearing housing are made of different materials.

7. The shaft assembly of claim 1, wherein the bearing housing includes a proximal recess to receive the distal catheter end, and the proximal recess includes a tapered wall.

8. The shaft assembly of claim 7, further comprising an adhesive joint between the tapered wall and the outer conduit.

9. A biostimulator delivery system comprising: an outer catheter having a distal catheter end and an inner lumen; a bearing housing mounted on the distal catheter end; an inner shaft extending through the inner lumen to a distal shaft end; a docking cap mounted on the distal shaft end, wherein the docking cap is coupled to the bearing housing and has a docking cavity to receive an attachment feature of a biostimulator; a pull wire extending through the lumen between the outer catheter and the inner shaft into the bearing housing such that an axial load applied to a proximal end of the pull wire causes a distal end of the pull wire to move within the bearing housing; and A handle is used to transmit torque to the inner shaft and axial load to the pull wire.

10. The biostimulator delivery system of claim 9, wherein the inner shaft comprises a torque shaft and the docking cap is coupled to a bearing housing via a bearing.

11. The biostimulator delivery system of claim 10, further comprising a pull ring housed within the bearing housing, wherein the pull wire is coupled to the pull ring such that an axial load applied to the pull wire causes the pull ring to move.

12. The biostimulator delivery system of claim 11, wherein the pull ring is axially located between the distal catheter end and the bearing.

13. The biostimulator delivery system of claim 11, wherein a proximal surface of the pull ring abuts against an inner surface of the bearing housing.

14. The biostimulator delivery system of claim 9, wherein the bearing housing includes a proximal recess to receive the distal catheter end, and the proximal recess includes a tapered wall.

15. A biostimulator system comprising: A biostimulator having an attachment feature; as well as A biostimulator delivery system includes: an outer catheter having a distal catheter end and an inner lumen, a bearing housing mounted on the distal catheter end, an inner shaft extending through the inner lumen to the distal shaft end, a docking cap mounted on the distal shaft end, wherein the docking cap is coupled to the bearing housing and has a docking cavity to receive an attachment feature of a biostimulator, and a pull wire extending through the inner lumen between the outer catheter and the inner shaft into the bearing housing so that an axial load applied to the proximal end of the pull wire causes the distal end of the pull wire to move within the bearing housing.

16. The biostimulator system of claim 15, wherein the inner shaft comprises a torque shaft, and the docking cap is coupled to the bearing housing via a bearing.

17. The biostimulator system of claim 16, further comprising a pull ring housed within the bearing housing, wherein the pull wire is coupled to the pull ring such that an axial load applied to the pull wire causes the pull ring to move.

18. The biostimulator system of claim 17, wherein the pull ring is axially located between the distal catheter end and the bearing.

19. The biostimulator system of claim 17, wherein a proximal surface of the pull ring abuts against an inner surface of a bearing housing.

20. The biostimulator system of claim 15, wherein the bearing housing includes a proximal recess to receive a distal catheter end, and the proximal recess includes a tapered wall.

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