Patent Description:
Leadless pacemakers nowadays are typically composed of, among others, a proximal end of a leadless pacemaker, a packaging housing, a ring electrode, a battery, electrical components, a distal end of a leadless pacemaker, and a head electrode, and are principally implanted into a patient's ventricle to sense pacing pulses. The distal end of a leadless pacemaker includes a fixation element, which is configured to attach to the inner wall of the ventricle, and the proximal end of a leadless pacemaker includes a retrieval docking structure, which is configured to partial or entire retrieve the pacemaker from the patient's body, if desired. However, since the leadless pacemaker is desired to have a small overall size (usually not greater than <NUM><NUM>), the retrieval docking structure in the proximal end of the leadless pacemaker has a relative small size. This, however, increases the difficulty in aligning and docking the retrieval docking structure with a retrieval system. In particular, when the distal end employs an active helical fixation method, after docking, the retrieval docking structure at the proximal end is also required to function for torque transmission and to be easily centered to facilitate its entry into a retrieval cup of a delivery device. Therefore, this structure is subject to stringent requirements. The success rate of capturing and retrieving a leadless pacemaker using the delivery device largely depends on the probability of successful docking between the retrieval docking structure and the delivery device, as well as the operator's experience. Therefore, such leadless pacemakers are associated with difficult docking and fail to provide a high success rate in retrieval. <CIT> relates to leadless pacemakers and related delivery and retrieval systems and methods.

It is an object of the present application to provide a retrieval docking component, a delivery device, a leadless pacemaker and a pacemaker system, to solve the problem of the capture and retrieval of conventional leadless pacemakers, which rely on operator's experience and has low success rate.

To this end, in a first aspect of the present application, there is provided a retrieval docking component for an implantable medical device, which comprises a base and a limiting part,.

Optionally, the radial outer dimension of the base gradually decreases from the distal end to the proximal end.

Optionally, the accommodation groove extends along an axis of the base and extends through the limiting part.

Optionally, in the retrieval docking component, the accommodation groove comprises, along its direction of extension, an imaginary centerline plane and two groove wall surfaces on opposite sides of the imaginary centerline plane,
wherein at least one groove wall surface of at least one accommodation groove comprises a first guide surface, and the first guide surface is gradually away from the imaginary centerline plane along a direction towards an exterior of the limiting part, thereby forming a flared opening.

Optionally, in the retrieval docking component, the accommodation groove comprises, along its direction of extension, an imaginary centerline plane and two groove wall surfaces on opposite sides of the imaginary centerline plane, wherein the limiting part comprises a second guide surface, and the second guide surface is joined to at least one groove wall surface and is gradually away from the imaginary centerline plane along a direction towards the distal end.

Optionally, in the retrieval docking component, the accommodation groove comprises, along its direction of extension, an imaginary centerline plane and a groove bottom surface intersecting the imaginary centerline plane,
wherein the groove bottom surface of at least one accommodation groove comprises a third guide surface, and the groove bottom surface extends to the proximal end and gradually approaches the axis of the base as extending.

Optionally, in the retrieval docking component, the radial outer dimension of the limiting part gradually decreases from distal end to proximal end.

Optionally, in the retrieval docking component, the limiting part comprises a stop surface that is oriented towards the distal end, wherein the stop surface forms an angle not greater than <NUM>° with a direction pointing to the distal end along an axis of the base.

Optionally, in the retrieval docking component, the limiting part comprises a docking structure oriented towards the proximal end, wherein the docking structure comprises a center coincident with an axis of the base and is configured to mate with a sheath of the delivery device.

Optionally, in the retrieval docking component, the limiting part comprises four accommodation grooves uniformly distributed along its circumference.

Optionally, the retrieval docking component further comprises a capture wing, wherein the capture wing comprises a first end connected to the limiting part and a second end, and the second end is a free end,
the capture wing comprising, when not stressed, an uncollapsed configuration in which the capture wing is gradually outwardly as extending towards the distal end of the base, wherein a distance from the free ends to an axis of the base is greater than a maximum distance between an outer periphery of the limiting part and the axis of the base.

Optionally, in the retrieval docking component, the capture wing is transitioned under the action of an external confining structure into a collapsed configuration;
wherein when the capture wing is in the collapsed configuration, the free end extends towards the distal end and wherein a distance from the free end to the axis of the base is not greater than the maximum distance between the outer periphery of the limiting part and the axis of the base.

Optionally, in the retrieval docking component, the capture wings are elastic sheets and achieve a transition between the uncollapsed and collapsed configurations by elastic deformation.

Optionally, the retrieval docking component comprises two capture wings, wherein the limiting part comprises two accommodation grooves along its circumference, and the capture wings and the accommodation grooves are alternately arranged uniformly along the circumference of the limiting part.

To the above end, in a second aspect of the present application, there is provided a delivery device configured to be connected to the retrieval docking component as defined above. The delivery device comprises a snare and sheath,.

Optionally, in the delivery device, the snare comprises a U-shaped section located at the distal end and extensions joined to the U-shaped section at open ends thereof, wherein when the snare is in an initial configuration where it is not stressed, an extending direction of the U-shaped section forms an angle with an extending direction of the extension.

Optionally, the delivery device further comprises a retrieval cup, the retrieval cup is movably disposed along the axis of the sheath, wherein the retrieval cup comprises a distal end that is open, wherein the retrieval cup is configured to sheathe the retrieval docking component and a body of the implantable medical device from a proximal end to a distal end of the retrieval docking component.

To the above end, in a third aspect of the present application, there is provided a leadless pacemaker, which comprises a leadless pacemaker body and the retrieval docking component as defined above, wherein the base of the retrieval docking component is connected to a proximal end of the leadless pacemaker body.

To the above end, in a fourth aspect of the present application, there is provided a leadless pacemaker system, which comprises the delivery device as defined above and the leadless pacemaker as defined above.

In summary, the present application provides a retrieval docking component, a delivery device, a leadless pacemaker and a pacemaker system. The retrieval docking component includes a base and a limiting part. A distal end of the base along the axial direction is configured for connection with a body of an implantable medical device, and a proximal end of the base along the axial direction is connected to the limiting part. A radial outer dimension of the limiting part is greater than a radial outer dimension of the proximal end of the base. The limiting part comprises at least two accommodation grooves along its circumference, which are open outwardly along radial direction of the limiting part and configured to capture a snare of a delivery device.

With this arrangement, the structure of the retrieval docking component is simple and provides adequate and reasonable accommodation space to the retrieval snare in a limited space. After the snare of the delivery device loops the implantable medical device, and moving and retracted towards the proximal end, it can slide along the base to abut and engage with the limiting part, and capture in the accommodation grooves. In this way, enabling the delivery device conveniently and reliably form a connection with the retrieval docking component, increasing success rate of retrieval and docking between the retrieval docking component and the delivery device and reducing the docking difficulty. Further, when the snare is captured in the accommodation grooves, it can also adapt for torque transmission and easy aligning and docking between the delivery device and the retrieval docking component with respect to each other, increasing convenience in retrieval of the implantable medical device.

Those of ordinary skill in the art would appreciate that the following drawings are presented merely to enable a better understanding of the present application rather than to limit the scope thereof in any sense, in which:.

Objects, features and advantages of the present application will become more apparent upon reading the following more detailed description, which is set forth by way of particular embodiments with reference to the accompanying drawings. Note that the figures are provided in a very simplified form not necessarily drawn to exact scale for the only purpose of helping to explain the disclosed embodiments in a more convenient and clearer way. In addition, structures shown in the figures are usually a part of actual structures. In particular, as the figures tend to have distinct emphases, they are often drawn to different scales.

As used herein, the singular forms "a", "an" and "the" include plural referents. As used herein, the term "or" is generally employed in the sense of "and/or", "several" is generally employed in the sense of "at least one" and "at least two" is generally employed in the sense of "two or more". Additionally, the use of the terms "first", "second" and "third" herein is intended for illustration only and is not to be construed as denoting or implying relative importance or as implicitly indicating the numerical number of the referenced item. Accordingly, defining an item with "first", "second" or "third" is an explicit or implicit indication of the presence of one or at least two such items. The term "proximal end" generally refers to an end closer to an operator, and the term "distal end" generally refer to an end closer to a lesion in a patient (i.e., farther away from the operator). The terms "one end" and "the other end", as well as "proximal end" and "distal end", are generally used to refer to opposite ends including the opposite endpoints, rather than only to the endpoints. The terms "mounting", "coupling" and "connection" should be interpreted in a broad sense. For instance, a connection may be a permanent, detachable or integral connection, or a mechanical or electrical connection, or a direct or indirect connection with one or more intervening media, or an internal communication or interaction between two elements. As used herein, when an element is referred to as being "disposed on" another element, this is generally intended to only mean that there is a connection, coupling, engagement or transmission relationship between the two elements, which may be either direct or indirect with one or more intervening elements, and should not be interpreted as indicating or implying a particular spatial position relationship between the two elements, i.e., the element may be located inside, outside, above, under, beside, or at any other location with respect to the other element, unless the context clearly dictates otherwise. Those of ordinary skill in the art can understand the specific meanings of the above-mentioned terms herein, depending on their context.

A description is set forth with reference to the accompanying drawings.

Reference is made below to <FIG>. <FIG> schematically illustrates a leadless pacemaker and a delivery device according to an embodiment of the present application, which have not been connected to each other yet. <FIG> schematically illustrates a leadless pacemaker and a delivery device according to an embodiment of the present application, which have been connected to each other. <FIG> schematically illustrates a leadless pacemaker according to an embodiment of the present application, which has been captured in a retrieval cup. <FIG> shows a proximal end of a retrieval docking component according to an embodiment of the present application. <FIG> is a side view of the retrieval docking component of <FIG>. <FIG> is a schematic illustration of a snare according to an embodiment of the present application. <FIG> shows a comparative example of a limiting part according to an embodiment of the present application. <FIG> shows another comparative example of the limiting part according to an embodiment of the present application. <FIG> schematically illustrates a leadless pacemaker and a delivery device according to another embodiment of the present application, which have not been connected to each other yet. <FIG> schematically illustrates a leadless pacemaker and a delivery device according to another embodiment of the present application, which have been connected to each other. <FIG> schematically illustrates a leadless pacemaker according to another embodiment of the present application, which has been captured in a retrieval cup. <FIG> shows a proximal end of a retrieval docking component according to another embodiment of the present application, in which capture wings are in an uncollapsed configuration. <FIG> is a side view of the retrieval docking component of <FIG>. <FIG> shows a proximal end of a retrieval docking component according to yet another embodiment of the present application, in which capture wings are in a collapsed configuration.

In interventional treatment, it is often necessary to use a delivery device to deliver an implantable medical device to a predetermined site through a natural lumen in a patient's body and fix it at the predetermined site. In some application scenarios, after the implantation, it is also necessary to use a delivery device to remove the implantable medical device from the predetermined site to facilitate adjustment of the implant site, or replacement and maintenance of the implantable medical device. Here, according to the present application, non-limiting examples of the implantable medical device may include leadless pacemakers.

A description is set forth below with reference to <FIG> in the context of the implantable medical device being a leadless pacemaker, as an example. It should be understood that the leadless pacemaker is merely a non-limiting example of the implantable medical device, and any person of skill in the art may configure a retrieval docking component <NUM> on other implantable medical devices in accordance with embodiments of the present application, and retrieve and dock the implantable medical device with a corresponding delivery device <NUM>.

The leadless pacemaker includes a leadless pacemaker body <NUM> and a retrieval docking component <NUM>, and a distal end of the retrieval docking component <NUM> (the left end in <FIG>) is connected to a proximal end of the pacemaker body <NUM> (the right end in <FIG>). Here, the connection of the retrieval docking component <NUM> and the pacemaker body <NUM> may be fixed, e.g., welded, adhesive or integral, or detachable, e.g., snap or threaded. In the example of <FIG>, the leadless pacemaker body <NUM> is generally cylindrical, and its distal end (the left end in <FIG>) includes a fixation element <NUM>, which is configured to pierce and anchor to the heart at a predetermined site, for example, barb fixation after screwing, piercing and etc. The retrieval docking component <NUM> is configured to be captured by and connected to a delivery device <NUM>. The delivery device <NUM> includes a snare <NUM> and a sheath <NUM>. The snare <NUM> is movably disposed along an axis of the sheath <NUM> and to loop around the exterior of the leadless pacemaker. With combined reference to <FIG>, during the capture and connection of the leadless pacemaker by and with the delivery device <NUM>, the snare <NUM> is retracted towards the proximal end, allowing the snare <NUM> to come into engagement with the retrieval docking component <NUM>, and eventually completing the connection of the retrieval docking component <NUM> and the delivery device <NUM>.

Referring to <FIG> and <FIG>, in conjunction with <FIG>, in an exemplary embodiment, the retrieval docking component <NUM> includes a base <NUM> and a limiting part <NUM>. A distal end of the base <NUM> along the axial direction (the upper end in <FIG>) is configured for connection with the leadless pacemaker body <NUM>, and a proximal end of the base <NUM> along the axial direction (the lower end in <FIG>) is connected to the limiting part <NUM>. A radial outer dimension of the limiting part <NUM> is greater than a radial outer dimension of the proximal end of the base <NUM>. The limiting part <NUM> comprises at least two accommodation grooves <NUM> along its circumference. The accommodation grooves <NUM> are open outwardly along radial directions of the base <NUM> and configured to capture the snare <NUM> of the delivery device <NUM>. Optionally, the radial outer dimension of the base <NUM> gradually decreases from its distal end to proximal end. This allows the snare <NUM>, when moving and retracted towards proximal end after capturing the leadless pacemaker body <NUM>, to slide inwardly along the base <NUM> that gradually decreases towards proximal end.

A description is set forth below of radial outer dimensions of the components described herein. Taking the base <NUM> as an example, the radial outer dimension of the base <NUM> refers to the diameter of a maximum outer enveloping circle of its cross-sectional shape that is perpendicular to its axis. In an alternative example, the cross-section of the base <NUM> is circular, and the radial outer dimension is its outer diameter. In an alternative example, the cross-section of the base <NUM> is polygonal, and the radial outer dimension is the diameter of its circumcircle. In further alternative embodiments, the cross-section of the base <NUM> comprises multi-lobed shape, gear shape or otherwise irregular shape, and the radial outer dimension is the diameter of its outer enveloping circle. The radial outer dimensions of the other components are defined in a similar way, and reference can be made to the foregoing description of the radial outer dimension of the base <NUM> for more details.

It is noted that, by the phrase "the radial outer dimension of the base <NUM> gradually decreases from its distal end to proximal end", it is intended to mean that the base <NUM> is overall tapered from the distal end to proximal end, but not that the radial outer dimension of the base <NUM> necessarily decreases linearly. In some alternative embodiments, the base <NUM> may include some constant diameter sections where the radial outer dimension of the base <NUM> remains the same. However, overall, the radial outer dimension of the base <NUM> generally decreases from the distal end to proximal end.

Optionally, the accommodation grooves <NUM> extend along axial direction of the base <NUM> and extend through the limiting part <NUM>. Through configuring the accommodation grooves <NUM> to extend along axial direction of the base <NUM>, the snare <NUM>, when captured, can extend towards the proximal end along the axial direction of the base <NUM>. This can facilitate the application of a force to the snare <NUM>. It is noted that, by the phrase "the accommodation grooves <NUM> extend along axial direction of the base <NUM>", it does not strictly mean that the accommodation grooves <NUM> necessarily extend in parallel to the axis of the base <NUM>. Rather, there may be a small angle between the two. For example, in some embodiment, the angle is configured to be not greater than <NUM>°.

Since the radial outer dimension of the limiting part <NUM> is greater than the radial outer dimension of the proximal end of the base <NUM>, when the snare <NUM> of the delivery device <NUM> moves and is retracted to proximal end after engaging the leadless pacemaker, it will slide to proximal end until it comes into abutment with the limiting part <NUM>. Then, it is stopped by the limiting part <NUM> that has a larger radial outer dimension and is captured in the accommodation grooves <NUM>, thereby, allowing a reliable and convenient connection to be established between the delivery device <NUM> and the retrieval docking component <NUM>, increasing success rate of docking and retrieval between the retrieval docking component <NUM> and the delivery device <NUM> and reducing docking difficulty. Furthermore, when captured in the accommodation grooves <NUM>, the snare <NUM> will be prevented from circumferential displacement by the accommodation grooves <NUM>. This can facilitate torque transmission and mutual aligning and docking between the delivery device <NUM> and the retrieval docking component <NUM>, and hence convenient retrieval of the leadless pacemaker by using the delivery device <NUM>.

Referring to <FIG>, in an optional example, the snare <NUM> includes a U-shaped section <NUM> located at the distal end thereof and extensions <NUM> joined to the U-shaped section <NUM> at open ends thereof. When the snare <NUM> is in an initial configuration where it is not stressed, an angle is formed between the extending direction of the U-shaped section <NUM> and the extending direction of the extensions <NUM>. Optionally, a circumferential wall of the base <NUM> forms an angle of <NUM>° to <NUM>° with the axis of the base <NUM>. This can facilitate sliding of the snare <NUM> towards the proximal end of the base <NUM>, and can help the snare <NUM> form the angled configuration shown in <FIG>, which allows two arms of the U-shaped section <NUM> of the snare <NUM> to be captured in opposite accommodation grooves <NUM>.

Referring to <FIG> and <FIG>, the accommodation groove <NUM> comprises an imaginary centerline plane <NUM> and two groove wall surfaces <NUM> along the extending direction thereof (the vertical direction in <FIG>). The two groove wall surfaces <NUM> are located on opposite sides of the imaginary centerline plane <NUM>. It should be understood that, here, the imaginary centerline plane <NUM> is taken as an imaginary reference plane for illustrative purposes. The two groove wall surfaces <NUM> may be of the same shape and symmetrical with respect to the imaginary centerline plane <NUM>. The two groove wall surfaces <NUM> may be of different shapes and located on opposite sides of the imaginary centerline plane <NUM>.

Among at least one of the accommodation grooves <NUM>, at least one of the groove wall surfaces <NUM> includes a first guide surface <NUM>, which is gradually away from the imaginary centerline plane <NUM> along a direction towards exterior of the limiting part <NUM> (i.e., away from the center direction of the limiting part <NUM>), thereby forming a flared opening <NUM>. After the snare <NUM> slides inwardly along the base <NUM> until it comes into abutment with the limiting part <NUM>, it is additionally retracted towards proximal end, and the sheath <NUM> is displaced from a location away from an axis of the leadless pacemaker, as shown in <FIG>, to a location, as shown in <FIG>, that is, the sheath <NUM> moves in the direction of the axis of the leadless pacemaker. At the latter location, the snare <NUM> is in contact with the outer periphery of a proximal end of the limiting part <NUM> and is captured between the groove wall surfaces <NUM> of the accommodation grooves <NUM>. By configuring the first guide surface(s) <NUM>, the accommodation grooves <NUM> forms outwardly flared opening(s) <NUM>, facilitating sliding of the snare <NUM> into the accommodation grooves <NUM>. Optionally, the first guide surface <NUM> is inclined at an angle of <NUM>° to <NUM>° with respect to the imaginary centerline plane <NUM>, which can facilitate sliding of the snare <NUM> into the accommodation grooves <NUM>. In some embodiments, the first guide surface <NUM> is gradually away from the imaginary centerline plane <NUM> along a direction towards the distal end of the base <NUM>. That is to say, the first guide surface <NUM> flares outwardly and to a distal end as well, in order to facilitate sliding of the snare <NUM> into the accommodation grooves <NUM>.

It is noted that the groove wall surface <NUM> includes the first guide surface <NUM>. The first guide surface <NUM> may be provided by a portion of the groove wall surface <NUM>, or the entire groove wall surface <NUM> may be provided by the first guide surface <NUM>. In one of the accommodation grooves <NUM>, only one of the groove wall surfaces <NUM> may include a first guide surface <NUM>, while the other groove wall surface <NUM> is an ordinary wall surface extending in the same direction as the accommodation groove <NUM>. Optionally, the two groove wall surfaces <NUM> of one of the accommodation groove <NUM> both include a first guide surface <NUM>. Additionally, among at least two accommodation grooves <NUM> in the limiting part <NUM>, only one accommodation groove <NUM> may include the first guide surface(s) <NUM>, while the remaining one(s) is(are) regular groove(s) extending in the same direction(s) as the accommodation groove(s) <NUM>. Optionally, the two groove wall surfaces <NUM> of each accommodation groove <NUM> both include a first guide surface <NUM>.

With continued reference to <FIG> and <FIG>, in some embodiments, the limiting part <NUM> includes a second guide surface <NUM>, which is joined to at least one of the groove wall surfaces <NUM> and is gradually away from the imaginary centerline plane <NUM> along a direction towards the distal end (the upper end in <FIG>). It is noted that there is no limitation on the number of the second guiding surfaces <NUM> here. Among the groove wall surfaces <NUM> of several accommodation grooves <NUM>, optionally, only one groove wall surface <NUM> is joined to the second guide surface <NUM>, or all the groove wall surfaces <NUM> are joined to the second guide surface <NUM>. With combined reference to <FIG>, after the snare <NUM> is captured in the accommodation grooves <NUM>, it can be retracted to the proximal end so that the sheath <NUM> abuts and engages the limiting part <NUM>. The distal U-shaped section of the snare <NUM> extends substantially circumferentially around the base <NUM>, and the proximal ends of the snare <NUM> are deflected by the accommodation grooves <NUM> and then extend to the proximal end substantially along the axial direction of the base <NUM>. The snare <NUM> forms an approximately <NUM>° angle between its two sections, easily causing the snare <NUM> to produce concentrated stress at the deflection points, which causes rupture or other undesirable issues. The configuration of the second guide surface <NUM> allows for a transition of the snare <NUM> at the deflection points and mitigates the stress concentration on snare <NUM> to a certain extent. Optionally, the second guide surface <NUM> is inclined at an angle of <NUM>° to <NUM>° with respect to the imaginary centerline plane <NUM>, which can help snare <NUM> to form a desired final shape and experience less stress concentration.

Optionally, the accommodation groove <NUM> has a groove bottom surface <NUM> along the same direction as the accommodation groove <NUM>, and the groove bottom surface <NUM> intersects the imaginary centerline plane <NUM>. Among at least one of the accommodation grooves <NUM>, the groove bottom surface <NUM> includes a third guide surface <NUM>, which extends to the proximal end (bottom end in <FIG>) and gradually approaches the axis of the base <NUM> as it extends. Referring to <FIG>, in some embodiments, the sheath <NUM> will come into abutment with the limiting part <NUM> under an action of the snare <NUM> being retracted, the proximal end of the snare <NUM> is inserted into the sheath <NUM> and its extending direction is coincident with the axis of the base <NUM>, while the groove bottom surfaces <NUM> of the accommodation grooves <NUM> are offset from the axis of the base <NUM>, thus, the snare <NUM> is deflected along the extending direction as it is being pulled out of a proximal end of an accommodation groove <NUM>. With the configuration of the third guide surface <NUM>, allowing for a transition of the snare <NUM> at the deflection point at the proximal end of the accommodation groove <NUM> and thereby mitigate stress concentration on the snare <NUM> to a certain extent.

Optionally, the limiting part <NUM> comprises a stop surface <NUM> oriented towards the distal end, which forms an angle, which is not greater than <NUM>°, with a direction along the axial direction of the base <NUM> and pointing to distal end (upper end direction in <FIG>). As a result, an outer edge of the stop surface <NUM> is closer to the distal end than its inner edge (the two edges would be aligned if the angle were <NUM>°). The snare <NUM> gradually slides along the base <NUM> to the proximal end, and eventually come into abutment with the stop surface <NUM> and be stopped by the snare <NUM>, rather than sliding beyond the stop surface <NUM>. In the example of <FIG>, the angle formed by the stop surface <NUM> and the direction along the axial direction of the base <NUM> and pointing to distal end is <NUM>°.

Optionally, at least one of the following connections employ a circularly or otherwise a curved transition connection: the joint between the first guide surface(s) <NUM> and the remaining portion of the groove wall surface(s) <NUM>, the joint between the second guide surface <NUM> and the groove wall surface(s) <NUM>, the joint between the second guide surface <NUM> and the stop surface <NUM>, and the joint between the third guide surface(s) <NUM> and the remaining portion of the groove bottom surface(s) <NUM>, in order to reduce resistance to sliding of the snare <NUM>, or stress concentration of the snare <NUM> when it is tightened.

Referring to <FIG> and <FIG>, a distal end of the sheath <NUM> is configured to be aligned with the proximal end of the limiting part <NUM>, and abut and engage the proximal end of the limiting part <NUM> under an action of the snare <NUM> being retracted towards the proximal end. The limiting part <NUM> comprises a docking structure <NUM> oriented towards the proximal end. The docking structure <NUM> comprises a center coincident with the axis of the base <NUM> and is configured to mate with the sheath <NUM>. For example, the docking structure <NUM> may be a cylindrical projection or conical projection formed at the proximal end of the limiting part <NUM>. The distal end of the sheath <NUM> comprises a mating socket. After the docking structure <NUM> snaps into the socket of the sheath <NUM>, it allows the sheath <NUM> to be kept coaxial with the limiting part <NUM>. In addition, after the docking structure <NUM> snaps into the socket of the sheath <NUM>, it allows the sheath <NUM> to be prevented from radial displacement with respect to the limiting part <NUM>. This can avoid radial dislodgement of the sheath <NUM> from the limiting part <NUM> as a consequence of a radial reaction force generated when the snare <NUM> is retracted.

Optionally, when the snare <NUM> is in the initial configuration where it is not stress, the angle between the extending direction of the U-shaped section <NUM> and the extending direction of the extensions <NUM> is close or equal to the angle between the second guide surface <NUM> and the imaginary centerline plane <NUM>. This enables the snare <NUM> in the rest configuration to comprise a shape that is similar to a shape that the stop surface <NUM>, the second guide surface <NUM> and the groove wall surfaces <NUM> together form, which can reduce deformation of the snare <NUM> to a certain extent and can help reduce its stress concentration.

Referring to <FIG>, <FIG>, optionally, the at least two accommodation grooves <NUM> are arranged circumferentially around the limiting part <NUM> at <NUM>° interval. With this arrangement, when the snare <NUM> slides into two accommodation grooves <NUM> arranged at <NUM>° interval, an axis of the sheath <NUM> will coincide with the axis of the base <NUM> in the retrieval docking component <NUM>. This allows the sheath <NUM> to align, dock and connect with the limiting part <NUM>.

Optionally, the limiting part <NUM> comprises four accommodation grooves <NUM> evenly distributed along its circumference. In the example of <FIG>, the limiting part <NUM> comprises four accommodation grooves <NUM> evenly distributed along its circumference at an angular interval of <NUM>°. With this arrangement, when the snare <NUM> loops around the leadless pacemaker body <NUM> and is retracted to the proximal end, it can easily slide into an opposite accommodation grooves <NUM> (the two accommodation grooves <NUM> arranged at <NUM>° interval), resulting in a high success rate of retrieval and docking. <FIG> show two comparative examples. The example of <FIG> includes only two accommodation grooves <NUM> arranged in opposition and is therefore more demanding on an angular position of the limiting part <NUM> with respect to the snare <NUM>. Obviously, a success rate of retrieval and docking of this example is lower than that of the example of <FIG>. The comparative example of <FIG> includes six accommodation grooves <NUM> evenly distributed along its circumference. Despite the easy capture of the snare <NUM> into accommodation grooves <NUM>, it cannot be ensured that the snare <NUM> is captured in two accommodation grooves <NUM> arranged at <NUM>° interval. For example, the snare <NUM> may be captured into adjacent accommodation grooves <NUM> (the two accommodation grooves <NUM> arranged at <NUM>° interval), or into two of the accommodation grooves <NUM> with another accommodation groove <NUM> intervening between them (the two accommodation grooves <NUM> arranged at <NUM>° interval). In these cases, the sheath <NUM> cannot be aligned and docked with respect to the limiting part <NUM>.

Referring to <FIG> and <FIG>, the delivery device <NUM> further includes a retrieval cup <NUM> (for the purposes of illustration, only half circumference of the retrieval cup <NUM> is shown in <FIG>, but it would be appreciated that the retrieval cup <NUM> is actually circumferentially continuous). The retrieval cup <NUM> is movably disposed along the axis of the sheath <NUM>. The retrieval cup <NUM> has an open distal end and is configured to sheathe the retrieval docking component <NUM> and the leadless pacemaker body <NUM> from the proximal end to distal end of the retrieval docking component <NUM> (from the right end to left end in <FIG>). In order to mate therewith, the radial outer dimension of the limiting part <NUM> gradually decreases from distal end to proximal end (from top to bottom in <FIG>), facilitating the insertion of the retrieval cup <NUM>. A circumferential wall of the limiting part <NUM> optionally forms an angle of <NUM>° to <NUM>° with the axis of the base <NUM>, which facilitates the insertion of the retrieval cup <NUM>.

In embodiments of the present application, there is also provided a retrieval docking system for a leadless pacemaker, which includes a delivery device <NUM> and the leadless pacemaker as defined above.

Referring to <FIG>, in one embodiment, the retrieval docking component <NUM> further includes: capture wings <NUM>. One end of the capture wing <NUM> is connected to the limiting part <NUM> (for illustrative purposes, this end is referred to hereinafter as the "connected end <NUM>"), and the other end is a free end <NUM>. When not stressed, the capture wings <NUM> are in an uncollapsed configuration (as shown in <FIG>, <FIG> and <FIG>) where they extend towards the distal end of the base <NUM> (upper end in <FIG>) and gradually extend outwardly, which forms a stretch-out configuration towards distal end. Moreover, the distance from the free ends <NUM> to the axis of the base <NUM> is greater than the greatest distance from the outer periphery of the limiting part <NUM> to the axis of the base <NUM>. With this arrangement, one the one hand, the capture wings <NUM> can increase the capture area for the snare <NUM>, increasing the success rate of the snare <NUM> being captured in the accommodation grooves <NUM>. On the other hand, an accommodating space is increased around the joint of the limiting part <NUM> and the base <NUM>, facilitating the U-shaped section <NUM> of the snare <NUM> to be received at the accommodating space around the joint of the limiting part <NUM> and the base <NUM> during retrieval and docking. This allows shape and position of the snare <NUM> to be more easily adjusted, facilitating the successful sliding of the snare <NUM> into the accommodation grooves <NUM>.

Optionally, under the action of an external confining structure (e.g., the retrieval cup <NUM>), the capture wings <NUM> can transition into a collapsed configuration (as shown in <FIG> and <FIG>). When the capture wings <NUM> is in the collapsed configuration, the free ends <NUM> extends towards distal end (upper end in <FIG>); a distance from the free ends <NUM> to the axis of the base <NUM> is not greater than the greatest distance between the outer periphery of the limiting part <NUM> and the axis of the base <NUM>. The capture wings <NUM> are able to transition into the collapsed configuration under an action the retrieval cup <NUM> being sheathed. On one hand, this will not increase overall radial outer dimension after retrieval, which facilitates passage through blood vessels and tissue around a target. On the other hand, since the free ends <NUM> of the capture wings <NUM> in the collapsed configuration are located closer to the center of the limiting part <NUM> than in the uncollapsed configuration, they can also restrict the position of the snare <NUM> and avoid the snare <NUM> from dislodgement, in accordance with some embodiments.

Optionally, the capture wings <NUM> are elastic sheets and can be transitioned between the uncollapsed and collapsed configurations by elastic deformation. In some exemplary embodiments, the capture wings <NUM> may be integrally formed with the limiting part <NUM>. In optional embodiments, the capture wings <NUM> can be independently formed parts relative to the limiting part <NUM> and attached to the limiting part <NUM>, for example, by welding, adhesive bonding or riveting. Optionally, the capture wings <NUM> are made of a metal material, such as the superelastic shape-memory alloy TiNi-<NUM>, which can ensure that the capture wings <NUM> can be made with small dimensions while exhibiting suitable stiffness and elasticity. The suitable stiffness allows the capture wings <NUM> to maintain a certain shape when stopping the snare <NUM> in the uncollapsed configuration and can prevent them from being too soft to retain the snare <NUM> when shape and position adjustments are made to the snare <NUM>. The suitable elasticity allows the capture wings <NUM> to be pushed and transition into the collapsed configuration by the retrieval cup <NUM> when they abut against each other, ensuring that the capture wings <NUM> can smoothly rebound and collapse.

Referring to <FIG>, in one exemplary embodiment, the retrieval docking component <NUM> includes two capture wings <NUM>, and the limiting part <NUM> comprises two accommodation grooves <NUM> along its circumference. The capture wings <NUM> and the accommodation grooves <NUM> are alternately arranged uniformly along the circumference of the limiting part <NUM>. It is noted that, here, by the phase "the capture wings <NUM> and the accommodation grooves <NUM> are alternately arranged uniformly along the circumference of the limiting part <NUM>", it is intended to mean that, along the circumference of the limiting part <NUM>, the two capture wings <NUM> are spaced apart by one accommodation groove <NUM>, and the two accommodation grooves <NUM> are spaced apart by one capture wing <NUM>. Each capture wing <NUM> is spaced by <NUM>° from corresponding adjacent accommodation groove <NUM>, and the two capture wings <NUM> are arranged at <NUM>° interval. The two accommodation grooves <NUM> are arranged at <NUM>° interval. With this arrangement, a success rate of initial docking between the snare <NUM> and the retrieval docking component <NUM> can be increased.

Of course, the capture wings <NUM> are not limited to being implemented as sheets, and in some other embodiments, they may be structures of other shapes, such as snap engagement elements, profiled torsion bars, or the like. The retrieval cup <NUM> includes mating snap engagement elements, limiting grooves or other components for acting on the capture wings <NUM> to transition it from the uncollapsed configuration to the collapsed configuration. These components can be properly configured according to practical applications, without limiting the scope of the present application in any sense.

On the basis of the retrieval docking component <NUM> as defined above, in embodiments of the present application, there is also provided a leadless pacemaker including a leadless pacemaker body <NUM> and the retrieval docking component <NUM> as defined above. The base <NUM> of the retrieval docking component <NUM> is connected to a proximal end of the leadless pacemaker body <NUM>. In embodiments of the present application, there is also provided a leadless pacemaker system including a delivery device <NUM> and the leadless pacemaker as defined above. Since both the leadless pacemaker and the leadless pacemaker system incorporate the retrieval docking component <NUM> as defined above, they also offer the same benefits. The structures and principles of other components of the leadless pacemaker and the leadless pacemaker system, please refer to those known in the art, and further description thereof is omitted herein.

In summary, the present application provides a retrieval docking component, a delivery device, a leadless pacemaker and a pacemaker system. The retrieval docking component includes a base and a limiting part. A distal end of the base along the axial direction is configured for connection with a body of an implantable medical device, and a proximal end of the base along the axial direction is connected to the limiting part. A radial outer dimension of the limiting part is greater than a radial outer dimension of the proximal end of the base. The limiting part comprises at least two accommodation grooves along its circumference, which are open outwardly in radial directions of the limiting part and configured for capture a snare of a delivery device. With this arrangement, the structure of the retrieval docking component is simple and provides adequate and reasonable accommodation space to the retrieval snare in a limited space. After the snare of the delivery device loops the implantable medical device, and moving and retracted towards the proximal end, it can slide along the base to abut and engage with the limiting part, and capture in the accommodation grooves. In this way, enabling the delivery device conveniently and reliably form a connection with the retrieval docking component, increasing success rate of retrieval and docking between the retrieval docking component and the delivery device and reducing the docking difficulty. Further, when the snare is captured in the accommodation grooves, it can also adapt for torque transmission and easy aligning and docking of the delivery device and the retrieval docking component with respect to each other, increasing convenience in retrieval of the implantable medical device.

Claim 1:
A retrieval docking component (<NUM>) for an implantable medical device (<NUM>), said retrieval docking component comprising a base (<NUM>) and a limiting part (<NUM>),
wherein a distal end of the base (<NUM>) along an axial direction is configured to be connected to a body of the implantable medical device, wherein a proximal end of the base (<NUM>) along the axial direction is connected to the limiting part (<NUM>), wherein the limiting part (<NUM>) has a radial outer dimension that is greater than a radial outer dimension of the proximal end of the base (<NUM>); and
characterised in that
the limiting part (<NUM>) comprises at least two accommodation grooves (<NUM>) along a circumference thereof, and wherein the accommodation groove (<NUM>) is open outwardly along a radial direction of the base (<NUM>) and is configured to capture a snare (<NUM>) of a delivery device (<NUM>).