WO2007070793A2

WO2007070793A2 - Two-pitch threaded handle detachment system

Info

Publication number: WO2007070793A2
Application number: PCT/US2006/061925
Authority: WO
Inventors: David A. Kilmer; Robert Lulo
Original assignee: Cordis Development Corporation
Priority date: 2005-12-13
Filing date: 2006-12-12
Publication date: 2007-06-21
Also published as: WO2007070793A3

Abstract

An actuator for use with an implantable medical device deployment system that guides and deploys the medical device to a target location within a body vessel. The actuator includes a threaded portion which has at least two different pitch sizes.

Description

TWO-PITCH THREADED HANDLE DETACHMENT SYSTEM

Description

[001] This application claims the benefit of U-S. Provisional Patent Application No. 60/749,838, filed December 13, 2005, which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

[002] This invention generally relates to actuators or mechanisms for use with medical device deployment systems that actuate deployment of implantable medical devices at target locations within a human body vessel, and methods of using the same. More specifically, this invention generally relates to actuators that regulate the movement of control members which initiate the release of a medical device from a deployment system.

DESCRIPTION OF RELATED ART

[003] The use of catheter delivery systems for positioning and deploying therapeutic devices, such as dilation balloons, stents and embolic coils, in the vasculature of the human body has become a standard procedure for treating endovascular diseases. It has been found that such devices are particularly useful in treating areas where traditional operational procedures are impossible or pose a great risk to the patient, for example in the treatment of aneurysms in cranial blood vessels. Due to the delicate tissue surrounding cranial blood vessels, especially for example brain tissue, it is very difficult and often risky to perform surgical procedures to treat defects of the cranial blood vessels. Advancements in catheter deployment systems have provided an alternative treatment in such cases. Some of the advantages of catheter delivery systems are that they provide methods for treating blood vessels by an approach that has been found to reduce the risk of trauma to the surrounding tissue, and they also allow for treatment of blood vessels that in the past would have been considered inoperable.

[004] Typically, these procedures involve inserting the distal end of a delivery catheter into the vasculature of a patient and guiding it through the vasculature to a predetermined delivery site. An implantable medical device, such as an embolic coil or vascular stent, is attached to the end of a delivery member which pushes the medical device through the catheter and out of the distal end of the catheter into the delivery site. Some of the delivery systems associated with these procedures utilize an elongated control member, sometimes referred to as a control wire or pull wire, to activate the release and deployment of the medical device. For example, U.S. Patent No. 5,250,071 to Palermo, which is hereby incorporated herein by reference, describes a deployment system whereby interlocking clasps of the system and the coil are held together by a control wire. The control wire is moved proximally to disengage the clasps from each other and release the embolic coil.

[005] Additionally, U.S. Patent Application Serial No, 11/461,245, filed July 31, 2006, to Mitelburg, et al., which is hereby incorporated herein by reference for its disclosure of a

—^*- distal-portion detachment mechanism with which the present invention can be utilized, describes a deployment system wherein a control member engages a hook or an eyelet to attach a medical device to the deployment system. The control member is moved in a proximal direction to disengage it from the hook and release the medical device.

[006] There remains a need for mechanisms or methods for controlling and manipulating control members of various medical device deployment systems. There also remains a need for mechanisms or methods that reduce the strain on the control member while providing a quick and timely deployment of the implantable medical device at a target location within a body vessel,

SUMMARY OF THE INVENTION

[007] In accordance with one embodiment or aspect of the present invention, an actuator is provided for use with an implantable medical device deployment system that includes a control member which initiates the release of an implantable medical device from the deployment system upon movement of the control member. The actuator comprises an actuator body which can be operatively connected to the control member. The actuator body includes a threaded portion that can be threadably connected to the deployment system so that rotational movement of the actuator body causes the actuator and the control member connected therewith to move relative to the deployment system to release the medical device. The threaded portion of the actuator body includes a pitch that has at least a first pitch size and a second pitch size wherein the first and second pitch sizes are different from each other.

[008] In accordance with further embodiment or aspect of the present invention, a deployment system for delivering an implantable medical device to a target location of a body vessel is provided. The deployment system comprises a generally elongated carrier member having a proximal end portion and a distal end portion and an implantable medical device releasably attached to the distal end portion of the carrier member. The deployment system also includes a control member whose movement causes the release of the implantable medical device from the distal end portion of the carrier member. Additionally, the deployment system also includes an actuator having a threaded portion that is threadably connected to a corresponding threaded portion of the carrier member located at the proximal end portion of the carrier member. The control member is connected to the actuator, and rotational movement of the actuator causes the actuator to move in an axial direction relative to the carrier member, thereby causing movement of the control member in an axial direction to release the medical device form the distal end portion of the carrier member. Further, one of the threaded portion of the actuator and the threaded portion of the carrier member includes a pitch that has at least a first pitch size and a second pitch size wherein the first pitch size and said second pitch size are different from each other. [009] In accordance with yet another embodiment or aspect of the present invention, a deployment system delivers an implantable medical device to a target location of a body vessel. The deployment system comprises a generally elongated carrier member having a proximal end portion and a distal end portion and an implantable medical device releasably attached to the distal end portion of the carrier member. The deployment system also includes a control member whose movement causes the release of the implantable medical device from the distal end portion of the carrier member. Additionally, the deployment system includes an actuator movably connected to the proximal end portion of the carrier member wherein the actuator is moveable in an axial direction relative to the carrier member. The control member is connected to the actuator, and movement of the actuator relative to the carrier member causes movement of the control member to release the medical device from the distal end portion of the carrier member. Further, the deployment system includes a regulator that changes the rate of relative axial movement between the actuator and the carrier member. [0010] In accordance with a further embodiment or aspect of the present invention, a method is provided for deploying an implantable medical device to a target location of a body vessel. The method comprises providing a deployment system including a carrier member having a proximal end portion and a distal end portion and an implantable medical device releasably connected to the distal end portion of the carrier member. The medical device is released from the distal end portion of the carrier member upon movement of a control member. The deployment system also includes an actuator threadably connected to the proximal end portion of the carrier member. The actuator includes a thread that has at least two different pitch sizes. The control member is connected to and moveable with the actuator. The method further comprises positioning the implantable medical device generally adjacent to a target location within the body vessel. Rotating the actuator relative to the carrier member to cause axial movement of the actuator relative to the carrier member, thereby moving the control member and releasing the implantable medical device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a cross-sectional view of an implantable medical device deployment system utilizing one embodiment of an actuator in accordance with the present invention; [0012] Fig. 2 is a front perspective view of the distal end of the carrier member of Fig. 1 with portions broken away to show the engagement member; and

[0013] Fig, 3 is a cross-sectional view of the deployment system of Fig. 1, shown with the actuator in the actuated position.

DESCRIPTIOM OF THE PREFERRED EMBODIMENTS

[0014] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate manner.

[0015] Figs. 1-3 illustrate an implantable medical device deployment system, generally designated at 10, utilizing one embodiment of a distal end portion deployment system suitable for use with an actuator or mechanism, generally designated at 12, in accordance with the present invention. The deployment system 10 is generally similar to the deployment system disclosed in U.S. Patent Application Serial No. 11/461,245, filed July 31, 2006, to Mitelburg et al., which has been incorporated by reference. However, it will be understood that the actuator of the present invention can be used in conjunction with various types of deployment systems, having various configurations, features and attachment and release mechanisms, such as the deployment system disclosed in U.S. Patent No. 5,250,071, which has been incorporated by reference. [0016] The deployment system 10 is comprised of a generally hollow elongated carrier member or pusher 14 having a distal end portion 16 and a proximal end portion 18. Preferably, the carrier member 14 is a hypotube that may be comprised of a biocompatible material, such as stainless steel. The hypotube typically will have a diameter of between about 0.010 inch (0.254 mm) and about 0.015 inch (0.381 mm), a preferred tube having a diameter of approximately 0,013 inch (0.330 mm). Such a carrier member 14 is suitable for delivering and deploying implantable medical devices, such as embolic coils, vascular stents or the like, to target locations, typically aneurysms, within the neurovasculature, but differently sized carrier members comprised of other materials may be useful for different applications .

[0017] An engagement member 20 is associated with the distal end portion 16 of the carrier member 14. Illustratively, the engagement member 20 comprises an elongated wire with a distal length thereof loosely bent in half to define an opening 22 (Fig. 2) . The proximal end or ends 24 of the engagement member 20 are fixedly connected to the carrier member 14 at a location proximal to the distal end portion 16.

[0018] In one alternative embodiment, the engagement member 20 can comprise a flat ribbon defining the opening 22 at a distal portion thereof. In either embodiment, the engagement member 20 is preferably deformable to the up-turned condition illustrated in Figs. 1 and 2- Additionally, the engagement member 20 is preferably elastically deformable to the up-turned condition of Figs. 1 and 2, such that it will return to a substantially flat condition, illustrated in Fig. 3, when not otherwise constrained, as will be explained in more detail below. The engagement member 20 may be comprised of any of a number of materials, including nitinol and stainless steel. The function of the engagement member 20 will be described in greater detail herein.

[00X9] The deployment system 10 further includes a control member 26, such as a control wire or pull wire, received within the lumen 28 of the carrier member 14 and operatively connected to the actuator 12. The control member 26 may be a wire comprised of any of a number of materials, including nitinol, and preferably, is sufficiently stiff to be advanced and/or retracted within the lumen 28 of the carrier member 14. The function of the control member 26 will be described in greater detail herein.

[0020] As shown in Figs. 1 and 2, an implantable medical device 30, such as the illustrated embolic coil, is releasably attached to the distal end portion 16 of the carrier member 14 by the engagement member 20. However, it will be appreciated that virtually any implantable medical device may be delivered and deployed by the deployment system.

[0021] To connect the implantable medical device 30 to the distal end portion 16 of the carrier member 14, an aperture- containing proximal end portion 32 of the implantable medical device 30 is placed adjacent to opening 22 of the engagement member 20, which is then deformed to the up-turned condition of Figs. 1 and 2. Alternatively, the opening 22 may be moved to the up-turned condition prior to placement of the implantable medical device 30. In the up-turned condition, at least a portion of the opening 22 passes through the aperture of the proximal end portion 32.

[0022] As described herein, the engagement member 20 is preferably elastically deformable to the up-turned condition of Figs. 1 and 2 so it will tend to return to a substantially flat condition as illustrated in Fig. 3. In order to prevent this, and to consequently lock the implantable medical device 30 to the engagement member 20, the distal end portion 33 of the control member 26 is moved axially through the opening 22 to the position shown in Figs. 1 and 2, In this connected condition, the control member 26 holds the engagement member 20 in the upturned condition, and the engagement member 20 releasably secures the proximal end portion 32 of the implantable medical device 30 to the distal end portion 16 of the carrier member 14, [0023] The actuator 12 is moveably connected to the proximal end portion 18 of the carrier member 14 and can move axially in a proximal direction from the position shown in Fig. 1 to the position shown in Fig. 2. When desired, for example in a deployment system in which the release of the medical device is caused by movement of the actuator 12 in a distal direction, the actuator 12 can also move axially in a distal direction from the position shown in Fig. 2 to the position shown in Fig. 1. [0024] The actuator 12 includes a gripping portion 34 and a threaded portion 36. The gripping portion 34 can be configured to be gasped by hand, medical instrument or both. Preferably, the gripping portion 34 functions as a percutaneous handle and has a gripping surface, such as a knarled surface or protruding wings.

[0025] The threaded portion 36 of the actuator 12 is configured to threadable engage a corresponding threaded portion 38 of the proximal end portion 18 of the carrier member 14. The threaded engagement between the actuator 12 and the carrier member 14 can be any suitable threaded connection. In the illustrated embodiment, the threading of the threaded portion 36 of the actuator 12 comprises a groove 40 and the threading of the corresponding threaded portion 38 of the proximal end portion 18 of the carrier member 14 comprises one or protrusions 42 which engage and follow the groove 40 as the actuator 12 is rotated relative to the carrier member 14. In an alternative embodiment, the outer surface of the proximal end 18 of the carrier member 14 could include threading in the form of a groove, and the threaded portion of the actuator 12 could include a protrusion that engages and follows the groove. [0026] When the actuator 12 is threadably engaged with the carrier member 14, rotation of the actuator relative to the carrier member 14 causes the actuator 12 to move proximally or distally in an axial direction depending on the direction of relative rotation between the actuator and carrier member. [0027] Referring to Fig. 3, the grooved threading 40 located on the actuator 12 of this embodiment varies in pitch and has at least two different pitch sizes. For example, the pitch can have a first size equal to the distance D near or associated with the proximal end 44 of the threaded portion 36, and a second size equal to the distance D' near or associated with the distal end 46 of the threaded portion 36. In the illustrated embodiment, the first size of the pitch {distance D) is shorter than the second size of the pitch {distance D' } . In other words, the pitch is fine at or near the proximal end 44 and coarse at or near the distal end 46. However, depending on the desired use, the first pitch size {distance D) could be larger than the second pitch size (distance D' ) . Alternatively, the pitch could continually increase or decrease from the proximal end 44 to the distal end 46 of the threaded portion 36 of actuator 12,

[0028] Referring to Fig. 1, when the actuator 12 is rotated or unscrewed from the proximal end 18 of the carrier member 14, the projection 42 of threaded portion 38 of the carrier member 14 follows along the groove 40 and causes the actuator 12 to move axially in a proximal direction relative to the carrier member 14, As the projection 42 follows along the section of the groove 40 having a pitch size of D, the actuator 12 will have a first rate of axial movement relative to the carrier member 14. As actuator 12 is further rotated and the projection 42 follows along the section of the groove 40 having a pitch size of D' , the actuator 12 will have a second rate of axial movement relative to the carrier member which is faster than the first rate of axial movement. Thus, the threaded connection between the threaded portion 36 of the actuator 12 and the threaded portion 40 of the proximal end portion 18 of the carrier member 14 functions as a regulator that changes the rate of axial movement of the actuator relative to the carrier member.

[0029] The rate of axial movement of actuator 12 can be controlled by the speed at which the actuator is rotated relative to the carrier member and the size of the pitch of the threading of the actuator. For example, at a constant speed of actuator rotation relative to the carrier member, a smaller or finer pitch size will result in relatively slower axial movement of the actuator relative to the carrier member, and a larger or coarser pitch size will result in relatively faster axial movement of the actuator relative to the carrier member. Thus, the size of the pitch can be tailored to the desired use. [0030] As discussed above, the control member 26 is connected to the actuator 12. Accordingly, as the actuator 12 is moved axially relative to the carrier member 14, the control member 26 is also moved axially, in the same direction and at the same rate as the actuator 12, relative to the carrier member 14. Therefore, in the illustrated deployment system 10 of Fig. 1, when the actuator 12 is rotated, the actuator 12 and the control member 26, which is connected to the actuator, move in a proximal direction relative to carrier member 14 and the engagement member 20. As explained above, the initial axial movement of the actuator 12 and the control member 26 is relatively slow, and as actuator 12 is further rotated, further movement in the axial direction is accelerated as compared to the initial movement. As will be appreciated from the above description, the initial relatively slow axial movement of the actuator 12 results in a slow tensioning of the control member which reduces the risk of breaking or snapping the control member during operation.

[0031] Referring to Fig. 3, and continuing with the same rotational direction noted immediately above, the control member 26 is moved proximally relative to the engagement member 20. In the illustrated detachment system for the medical device that is shown in the drawings, this proximal movement proceeds so that the distal end portion 33 of the control member 26 moves out of the opening 22 of the engagement member 20, Once the distal end portion 33 of the control member 26 is moved out of opening 22, the unconstrained engagement member 20 is free to allow release of the medical device. Fig, 3 shows the engagement returned to or moved to, its flat configuration, thereby releasing the medical device 30. This return can be due to a bias in the engagement member 20 or by a straightening-type of engagement with the medical device 30 as it separates from the detachment device.

[0032] According to one method of delivering the medical device 30, a tubular catheter (not shown) is fed into a body vessel until a distal end thereof is adjacent to a target location. Thereafter, the deployment system 10 and associated implantable medical device 30 are advanced through the catheter, using procedures and techniques generally known in the ait, until the device 30 is itself generally adjacent to the target location. Alternatively, the deployment system 10 and associated device 30 may be pre-loaded in the catheter, with the combination being fed through a body vessel to a target location. Other methods of positioning the implantable medical device 30 generally adjacent to a target location may also be practiced without departing from the scope of the present invention,

[0033] To more accurately position the engaged device 30, radiopaque markers (not illustrated) may be attached to the carrier member 14 or the device 30 itself. [0034] When the engaged device 30 has been properly positioned and oriented, the actuator 12 is grasped by hand or instrument at the gripping portion 34 and rotated relative to the carrier member 14. As the actuator 12 is rotated, the actuator and control member 26 initially move relatively slowly in a proximal direction as a result of the fine or short pitch size associated with the proximal end portion 44 of the threaded portion 36 of the actuator 12. As the actuator 12 is further rotated, the actuator 12 and control member 26 move proximally at a more accelerated rate, as a result of the coarse or larger pitch distance associated with the distal end portion 44 of the threaded portions 36 of the actuator 12. Referring to Fig. 3, as the control member 26 moves in a proximal direction, it comes out of engagement with the engagement member 20. The engagement member 20 is then allowed to return to its original substantially flat condition, or is moved to a release condition by engagement with another component of the system, thereby releasing the aperture-containing end portion 32 of the implantable medical device 30 and deploying the medical device 30. Release also can be achieved by or be faciliated by opposing relative movement between the engagement member 20 and the medical device 30. The control member 26 may be provided with a radiopaque portion to provide visual feedback to indicate when the device 30 has been released. [0035] When the implantable medical device 30 is disengaged from the engagement member 20, the deployment system 10 may be removed from the patient alone or in conjunction with the catheter.

[0036] It will be understood that the embodiments of the present invention which have been described are illustrative of some of the applications of the principles of the present invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention, including those combinations of features that are individually disclosed or claimed herein.

Claims

1. An actuator for use with an implantable medical device deployment system including a control member that initiates the release of an implantable medical device from the deployment system upon movement of the control member, the actuator comprising: an actuator body adapted to be operatively connected to the control member_f the actuator body including a threaded portion that is adapted to be threadably connected to the deployment system so that rotational movement of the actuator body causes the actuator and the control member connected therewith to move relative to the deployment system to release the medical device; and said threaded portion of the actuator body includes a pitch that has at least a first pitch size and a second pitch size, said first and second pitch sizes being different from each other.

2. The actuator of claim 1 in which the pitch causes rotational movement of the actuator to retract the actuator from the deployment device.

3. The actuator of claim 1 in which the pitch causes rotational movement of the actuator to advance the actuator toward the deployment device.

4. The actuator of claim 1 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, the first pitch size is associated with proximal end portion of the threaded portion, and the second pitch size is associated with the distal end portion of the threaded portion, and said first pitch size is smaller than said second pitch size .

5. The actuator of claim 1 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, the first pitch size is associated with the proximal end portion of the threaded portion, and the second pitch size is associated with the distal end portion of the threaded portion, and said first pitch size is larger than said second pitch size.

6. The actuator of claim 1 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, and the pitch size continually increases from the proximal end portion to the distal end portion of the threaded portion _*

7. The actuator of claim 1 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, and the pitch size continually decreases from the proximal end portion to the distal end portion of the threaded portion .

8. The actuator of claim 1 further included a gripping portion extending from said threaded portion.

9. The actuator of claim 1 in which the threaded portion of the actuator includes a grooved threading.

10, A deployment system for delivering an implantable medical device to a target location of a body vessel, comprising: a generally elongated carrier member having a proximal end portion and a distal end portion; an implantable medical device releasably attached to the distal end portion of the carrier member; a control member whose movement causes the release of the implantable medical device from the distal end portion of the carrier member; an actuator including a threaded portion that is threadably connected to a corresponding threaded portion of the carrier member located at the proximal end portion of the carrier member, and the control member being connected to said actuator, whereby rotational movement of the actuator causes the actuator to move in an axial direction relative to the carrier member, thereby causing movement of the control member in an axial direction to release the medical device from the distal end portion of the carrier member; and one of said threaded portion of the actuator and said threaded portion of said carrier member including a pitch that has at least a first pitch size and a second pitch size, said first pitch size and said second pitch size being different from each other.

11, The deployment system of claim 10 in which the pitch causes rotational movement of the actuator to retract the actuator from the deployment device.

12, The deployment system of claim 10 in which the pitch causes rotational movement of the actuator to advance the actuator toward the deployment device.

13. The deployment system of claim 10 in which the threaded portion of the actuator includes the pitch that has at least a first pitch size and a second pitch size.

14. The deployment system of claim 13 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, the first pitch size is associated with proximal end portion of the threaded portion, and the second pitch size is associated with the distal end portion of the threaded portion, and said first pitch size is smaller than said second pitch size,

15. The deployment system of claim 13 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, the first pitch size is associated with the proximal end portion of the threaded portion, and the second pitch size is associated with the distal end portion of the threaded portion, and said first pitch size is larger than said second pitch size.

16. The deployment system of claim 13 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, and the pitch size continually increases from the proximal end portion of the threaded portion to the distal end portion of the threaded portion.

17. The deployment system of claim 13 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, and the pitch size continually decreases from the proximal end portion of the threaded portion to the distal end portion of the threaded portion.

18. The deployment system of claim 10 in which the actuator further includes a gripping portion secured to said threaded portion.

19. The deployment system of claim 10 in which the control member comprises a wire.

20. A deployment system for delivering an implantable medical device to a target location of a body vessel, comprising: a generally elongated carrier member having a proximal end portion and a distal end portion; an implantable medical device releasably attached to the distal end portion of the carrier member; a control member whose movement causes the release of the implantable medical device from the distal end portion of the carrier member; an actuator movably connected to the proximal end portion of the carrier member, said actuator moveable in an axial direction relative to the carrier member, and the control member being connected to the actuator, whereby movement of the actuator relative to the carrier member causes movement of the control member to release the medical device from the distal end portion of the carrier member; and a regulator that changes the rate of relative axial movement between the actuator and the carrier member.

21. The deployment system of claim 20 in which the regulator is comprised of a threaded portion of the actuator and a corresponding threaded portion of the carrier member_r and at least one of said threaded portion of the actuator and threaded portion of the carrier member includes a pitch having at least a first pitch size and a second pitch size that varies from said first pitch size.

22. The deployment system of claim 20 in which the threaded portion of the actuator includes the pitch that has at least a first pitch size and a second pitch size.

23. The deployment system of claim 22 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, the first pitch size is associated with the proximal end portion of the threaded portion and the second pitch size is associated with the distal end portion of the threaded portion, and said first pitch size is smaller than said second pitch size.

24. The deployment system of claim 22 in which the threaded portion of the actuator has a proximal end portion and a distal end portion, the first pitch size is associated with the proximal end portion of the threaded portion and the second pitch size is associated with the distal end portion of the threaded portion, and said first pitch size is larger than said second pitch size.

25. The deployment system of claim 20 in which the actuator further includes a gripping portion secured to the threaded portion.

26. The deployment system of claim 20 in which the control member comprises a wire.

27. A method of deploying an implantable medical device to a target location of a body vessel, comprising: providing a carrier member having a proximal end portion and a distal end portion, an implantable medical device releasably connected to the distal end portion of the carrier member, said medical device being released from the distal end portion of the carrier member upon movement of a control member, an actuator threadably connected to the proximal end portion of the carrier member and having a thread that has at least two different pitch sizes, and the control member connected to and moveable with the actuator; positioning the implantable medical device generally adjacent to a target location within the body vessel; and rotating the actuator relative to the carrier member to cause axial movement of the actuator relative to the carrier member, thereby moving the control member and releasing the implantable medical device.

28. The method of claim 27 in which the rotating comprising rotating the actuator in a direction which causes the actuator to move axially in a proximal direction relative to the carrier member.