Implant deployment device

Abstract

An implant deployment device comprises an elongate delivery tube and a handle at a proximal end of the delivery tube. The handle comprises a control element such as a thumbwheel that is movable relative to a housing of the handle. This, in turn, moves a deployment component of the delivery tube, such as an outer sheath, to an extent sufficient to deploy an implant from the delivery tube. The handle also comprises a detent element that acts separately and simultaneously on the control element and on the deployment component The detent element is movable relative to the housing from an initial locked position, in which movements of the control element and the deployment component are blocked, to an unlocked position enabled for use, in which deploying movements of the control element and the deployment component are permitted.

Description

[0001]Implant^deployment^deviceThis invention relates to an implant deployment device that can be used as a delivery system todeploy an implant, such as a stent, at a target site within the vasculature or elsewhere within a patient’s body.Implant deployment devices typically comprise an elongate flexible delivery tube that extendsdistally from a proximal handle. The delivery tube may, for example, be a catheter that can be navigated through a patient’s vasculature to convey the implant to the target site.The delivery tube comprises concentric components such as rods, tubes or sheaths that retainthe implant before its deployment and that can then be moved relative to each other to deploythe implant. Commonly, the implant is released from the delivery tube by withdrawing an outersheath in a proximal direction to unsheathe the implant. For this purpose, the handle supportsany of various control elements such as a lever, a button or a thumbwheel that acts on thecomponents of the delivery tube, allowing a clinician to move those components as required toposition and to deploy the implant.It is, of course, essential that a deployment device enables accurate and reliable placement of animplant. For that purpose, the handle must be comfortable for a clinician to hold and manipulatewith either hand and the control elements must be easy to operate and intuitive to use. It istherefore desirable to locate key control elements such as a thumbwheel on a centrallongitudinal plane about which the handle is substantially symmetrical. Before deployment, the implant must be protected and held securely in the delivery tube. Deployment of the implant must occur only as a deliberate action controlled by a clinician andmust not occur accidentally, prematurely or partially, either before or during a procedure. Forexample, unintended movement of, or deliberate tampering with, a control element such as a thumbwheel could occur during packaging, shipping, storage and unpacking of the device. This could lead to unintended deployment of the implant, at least partially, even before a procedure begins.When a stenting procedure begins, a catheter for delivering the stent is typically introduced intothe anatomy via an introducer sheath. The force required to track the catheter through theintroducer sheath could cause an outer sheath of the catheter to move proximally relative to thehandle and other parts of the catheter, hence potentially causing unintended deployment of thestent during navigation to the target site. Inadvertent operation of a control element on thehandle could also cause unintended deployment of an implant. For all of these reasons, it desirable for a deployment device to have a lock or detent to prevent unintended deployment of an implant. The lock or detent must be released or overcome toinitiate deployment. A positive locking function is preferred as this can require a deliberaterelease action, distinct from a deployment action, to release the lock. However, the release actiontends to complicate use of the device. Moreover, there is a still a risk that a clinician could unlockthe device, begin the implant deployment process, relock the device, and continue deploymentlater. Bad practice such as this could result in poor implant delivery, compression or elongationof the implant, and damage to the implant or the surrounding vasculature. Another issue is that locking a control element such as a thumbwheel does not necessarily prevent inadvertent movement of components of the delivery tube. For example, a pull wire within the handle that couples a thumbwheel to the delivery tube can only act in tension and socannot prevent proximal movement of components of the delivery tube, even if the thumbwheelitself is locked. Moreover, the device may not give a clinician any visual or tactile warning that itis not suitable for use. It is against this background that the present invention has been devised. From one aspect, theinvention resides in an implant deployment device that comprises a delivery tube and a handleat a proximal end of the delivery tube. The handle comprises a control element that is movablerelative to a housing of the handle to move a deployment component of the delivery tube to an extent sufficient to deploy an implant from the delivery tube. The handle further comprises a detent element that acts separately on the control element and on the deployment component.The detent element is movable relative to the housing from a locked position, in whichmovement of the control element and the deployment component is blocked, to an unlockedposition in which movement of the control element and the deployment component ispermitted. Conveniently, the control element and the detent element can be located so as to beoperable respectively with a thumb of a hand holding the handle.The device can comprise a locking member that is engaged with the control element when thedetent element is in the locked position and that is disengaged from the control element bymovement of the detent element into the unlocked position. For example, the locking memberand the detent element may have opposed sliding surfaces that interact with a cam action duringmovement of the detent element to disengage the locking member from the control element.The locking member can be biased into engagement with the control element and disengagedfrom the control element against that bias. For example, the locking member may comprise alocking arm that supports a locking pawl, such that the locking pawl is biased into engagementwith the control element by resilience of the locking arm. The locking pawl may be supported bya ratchet hub that restricts the control element to unidirectional movement.The device may further comprise a unidirectional latch mechanism that is arranged to blockmovement of the detent element back from the unlocked position to the locked position. Such alatch mechanism can comprise latch formations on the detent element that are resilientlydeflectable around lugs fixed relative to the housing, and that may be unable to deflect backaround the lugs after the detent element reaches the unlocked position.The detent element may have a proximal portion exposed outside the housing in a positionadjacent to the control element and a distal portion within the housing acting on the deploymentcomponent. The exposed proximal portion of the detent element can comprise a grip protrusionthat is disposed distally of the control element and that is substantially aligned with the controlelement in a central longitudinal plane of the housing. Conveniently, the detent element can bemoved proximally relative to the housing into the unlocked position and the control element canthen be moved proximally relative to the housing to deploy the implant.The detent element may comprise a distal pawl that, when the detent element is in the locked position, is engaged with an adaptor that is disposed within the housing and is fixed to thedeployment component. The distal pawl may be engaged with the adaptor against resilient biasof the detent element, to move clear of the deployment component under that bias whendisengaged from the adaptor. When the detent element is in the locked position, the distal pawlmay be engaged between the adaptor and an opposed stop formation of the housing. A guideformation, which could be defined by the stop formation, can define a guide path to be followedby the distal pawl. Initially, the guide path can be transverse to a direction of movement of otherparts of the detent element into the unlocked position. For this purpose, the detent element maycomprise a flexure that allows the distal pawl to move relative to the other parts of the detent element when following the guide path. On being moved into the unlocked position, the detent element could instead disengage from alocking member that previously blocked movement of the deployment component, thereby torelease the locking member to move aside and to release the deployment component formovement. Alternatively, on being moved into the unlocked position, the detent element couldpivot a locking member that previously blocked movement of the deployment component torelease the deployment component for movement.The control element is apt to be a thumbwheel that can be turned to tension a pull elementconnected to the deployment component, hence retracting the deployment componentproximally to deploy the implant. The pull element may, for example, be wound onto a spool thatis coaxial with the thumbwheel about a common axis of rotation and that is offset along that axisfrom the thumbwheel. The pull element may follow a path that comprises a first leg extendingproximally from the deployment component to a pulley disposed proximally within the handlewith respect to the spool, and a second leg extending distally from the pulley to the spool. In thatcase, the pulley can be oriented with respect to the handle such that an entry of the first leg ofthe pull element onto the pulley lies substantially in a common plane with the thumbwheel andan exit of the second leg of the pull element from the pulley lies on the same side of that plane asthe spool.The inventive concept embraces a corresponding method of enabling an implant deploymentdevice to deploy an implant from a delivery tube of the device. The method comprises moving adetent element on a handle of the device from a locked position into an unlocked position. Thedetent element thereby releases a control element of the handle and a deployment component ofthe delivery tube from respective locked states for respective deployment movements relative toa housing of the handle. Subsequently, the control element can be moved to effect deployment ofthe implant by moving the deployment component of the delivery tube. That movement of thecontrol element can be restricted to unidirectional movement.The control element can be moved in a direction of movement corresponding to a direction ofmovement of the detent element into the unlocked position. For example, the detent element canbe moved by applying proximal force to the detent element at a location distal to the controlelement, and then the control element can be moved by applying proximal force to the controlelement. Movement of the detent element back to the locked position from the unlocked positioncan be prevented.The deployment component of the delivery tube can be released by disengaging a distal pawl ofthe detent element from an adaptor that is disposed within the housing and is fixed to thedeployment component. The distal pawl can be guided on a path that is transverse to a directionof movement of other parts of the detent element into the unlocked position.In summary, an implant deployment device of the invention comprises an elongate delivery tubeand a handle at a proximal end of the delivery tube. The handle comprises a housing and acontrol element such as a thumbwheel that is movable relative to the housing. That movement,in turn, moves a deployment component of the delivery tube, such as an outer sheath, to an extent sufficient to deploy an implant from the delivery tube. The handle also comprises a detent element that acts separately and simultaneously on the control element and on the deployment component. The detent element is movable relative to the housing from an initial locked position, in which movements of the control element and the deployment component are blocked, to an unlocked position enabled for use, in which deploying movements of the control element and hence of the deployment component are permitted. In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a side view of an implant deployment device of the invention; Figure 2 corresponds to Figure 1 but is cut away longitudinally to show internal features of the device; Figure 3 is a perspective view of the device from its distal end;Figure 4 is an exploded perspective view of the device from its proximal end;Figure 5 is a perspective view of a ratchet hub of the device; Figure 6 is a perspective view of a thumbwheel of the device; Figure 7 is a side view in longitudinal section of the ratchet hub of Figure 5 assembled with the thumbwheel of Figure 6; Figure 8 is an enlarged perspective view of a detent element of the device;Figures 9a and 9b are plan views cut away on lines A-A and B-B showing how the detent element of Figure 8 interacts with the ratchet hub of Figure 5 to unlock the thumbwheel; Figure 10 is a cut-away perspective view of the device with the thumbwheel unlocked as shown in Figure 11b and a distal pawl of the detent element unlocking a delivery tube of the device; Figures 11a and 11b are cut-away side views showing the distal pawl of the detentelement locking and unlocking the delivery tube;Figure 12 is an enlarged cut-away perspective view of a distal portion of the device, showing the distal pawl of the detent element locking the delivery tube; Figures 13a and 13b are enlarged cut-away plan views showing operation of a latch arrangement that blocks reverse motion of the detent element; andFigures 14a to 20b are schematic side views showing operation of alternative mechanisms for locking the delivery tube of the device.Referring firstly to Figures 1 to 4 of the drawings, an implant deployment device 10 comprisesan elongate flexible delivery tube 12 extending distally from a handle 14. The components of thehandle 14 are primarily made of injection-moulded plastics.The handle 14 has a hollow elongate case or housing 16 that is divided into two parts along acentral longitudinal plane 18 that contains the proximal end of the delivery tube 12. The housing16 is sized and shaped to fit comfortably into the grip of a clinician's hand and is substantiallysymmetrical about the central longitudinal plane 18 for ambidextrous use.A distally-tapering distal portion of the housing 16 supports a deployment control element inthe form of a thumbwheel 20. The thumbwheel 20 protrudes through a slot 22 in an upper sideof the housing 16 and is oriented in the central longitudinal plane 18. As will be explained,rotational movement of the thumbwheel 20 about an axis orthogonal to the central longitudinalplane 18 acts on the delivery tube 12 to deploy an implant such as a stent.In this example, the delivery tube 12 comprises an inner sheath 24 disposed within an outersheath 26 in concentric relation. An implant (not shown) can be accommodated in a distal endportion of the delivery tube 12, in an annular space defined by a radial gap between the innerand outer sheaths 24, 26. Proximal movement of the outer sheath 26 relative to the inner sheath24 exposes and releases the implant for deployment. For this purpose, the inner sheath 24 isfixed relative to the housing 16 whereas the outer sheath 26 is retractable proximally into thehousing 16. The outer sheath 26 can therefore be regarded as a movable deployment componentof the delivery tube 12.As best appreciated in Figure 2, a proximal end of the inner sheath 24 is in fluid communicationwith a rigid tubular shaft 28 that extends longitudinally through the housing 16. The shaft 28could instead be a proximal portion of the inner sheath 24. The shaft 28 terminates proximally ina Luer connector 30 that protrudes from the proximal end of the housing 16. Irrigation fluid canthereby be introduced into the inner sheath 24. Conversely, the outer sheath 26 terminatesproximally in a hub or adaptor 32 that can slide proximally with the outer sheath 26 along theshaft 28. The adaptor 32 can slide along most of the length of the shaft 28 to allow acorrespondingly large proximal movement, or stroke, of the distal end of the outer sheath 26.This enables the device 10 to deliver and unsheathe an implant of considerable length.The thumbwheel 20 acts on the outer sheath adaptor 32 by applying tension to a pull wire 34.The pull wire 34 is attached at one end to a proximal side of the outer sheath adaptor 32 and iswound at the other end around a spool 36 that is fixed to, and coaxial with, the thumbwheel 20.Proximal movement of the protruding part of the thumbwheel 20 winds the pull wire 34 ontothe spool 36.An idler pulley 38 located near the proximal end of the housing 16 guides the pull wire 34 alonga path within the housing 16 that extends between the spool 36 and the outer sheath adaptor 32.In following that path, the pull wire 34 extends proximally along a first leg from the outer sheathadaptor 32 to the idler pulley 38, bends around the proximal side of the idler pulley 38 withguidance from a circumferential groove in the outer edge of the idler pulley 38, and thenreverses in direction to extend distally along a second leg from the idler pulley 38 to the spool36.The first leg of the pull wire 34 lies on a longitudinal axis that is substantially aligned with thecentral longitudinal plane 18 and substantially parallel to the axis of movement of the outersheath adaptor 32 and the outer sheath 26 along the shaft 28. Conversely, as the spool 36 isoffset from the thumbwheel 20 along its axis of rotation, and as the thumbwheel 20 lies on thecentral longitudinal plane 18 for ambidextrous symmetry of the handle 14, the spool end of thesecond leg is similarly offset from the central longitudinal plane 18.To accommodate the different orientations of the first and second legs of the pull wire 34, theidler pulley 38 is inclined relative to the central longitudinal plane 18. In other words, the idlerpulley 38 turns about an axis that is transverse to and intersects, but is not orthogonal to, thecentral longitudinal plane 18. The inclination of the idler pulley 38 is such that the first leg of thepull wire 34 enters the idler pulley 38 substantially on the central longitudinal plane 18 whereasthe second leg of the pull wire 34 exits the idler pulley 38 out of the central longitudinal plane18, on the same side of that plane 18 as the spool 36. In this way, elegantly, the idler pulley 38initiates divergence of the second leg of the pull wire 34 from the central longitudinal plane 18as the pull wire 34 approaches the spool 36.Referring now also to Figures 5 to 8 of the drawings, the device 10 further comprises a ratchethub 40 shown in Figure 5 that is fixed to the housing 16 and an unlocking slider or detentelement 42 shown in Figure 8 that is movable relative to the housing 16. Advantageously, theratchet hub 40 and the detent element 42 each perform two different functions, as will now beexplained.When assembled as shown in Figure 7, the ratchet hub 40 shown in Figure 5 cooperates with thethumbwheel 20 shown in Figure 6 to restrict the thumbwheel 20 to unidirectional rotation,whereby the spool 36 attached to the thumbwheel 20 can only tension the pull wire 34 to retractthe outer sheath 26 proximally into the handle 14. The direction of rotation is such that,intuitively, the exposed part of the thumbwheel 20 must be moved proximally to effectcorresponding proximal movement of the outer sheath 26. Rotation of the thumbwheel 20 in theopposite direction is prohibited by the ratchet hub 40 because such movement could otherwisecause the pull wire 34 to become entangled within the handle 14, possibly preventingdeployment of an implant and so causing an implanting procedure to be abandoned.The thumbwheel 20 has an externally-knurled circumferential flange 44 that surrounds ashallow recess 46 provided in one side of the thumbwheel 20 as shown in Figure 6. The recess46 accommodates the ratchet hub 40 and has features that interact with the ratchet hub 40 tocontrol movement of the thumbwheel 20. The opposite side of the thumbwheel 20 is generallyflat and plain.More specifically, the recess 46 in the thumbwheel 20 has a stepped profile in radial section.That profile comprises outer and inner circumferential shoulders 48, 50, each facing radiallyinwardly toward the axis of rotation of the thumbwheel 20, and an integral central web 52within the inner shoulder 50 that defines the base of the recess 46. The circular outer shoulder48 defines the radially outer boundary of the recess 46. The central web 52 includes an integralspigot 54 that is centred on the axis of rotation.The inner shoulder 50 has a saw-toothed profile defining a unidirectional rack whose ratchetteeth 56 face radially inwardly toward the axis of rotation. Each ratchet tooth 56 has a radially-oriented lock face 58 and a ramp face 60 that is oriented at an obtuse angle to a radius of thethumbwheel 20. Conversely, the central web 52 is formed with a circumferential array ofnotches 62 that face axially, parallel to the axis of rotation. The notches 62 are equiangularlyspaced around the axis of rotation. In this example, the notches 62 are obtusely angled relativeto respective radii of the central web 52, hence allowing the notches 62 to overlap angularlywith their neighbours in the array.The ratchet hub 40 comprises a generally circular disc-like base plate 64 that fits snugly withinthe outer shoulder 48 of the thumbwheel 20 and has a central aperture to accommodate thespigot 54 of the thumbwheel 20. Integrally-moulded resilient ratchet pawls 66 are angularlyspaced about the central aperture on one face of the base plate 64, facing into the recess of thethumbwheel 20. The ratchet pawls 66 face in the same circumferential direction, opposed to thelock faces 58 of the ratchet teeth 56, and are biased radially outwardly by their resilience.As will be apparent from Figure 7, the tips of the ratchet pawls 66 can deflect radially inwardlyto surmount the ramp faces 60 of the ratchet teeth 56 as the thumbwheel 20 turns in thepermitted direction shown. Conversely, the tips of the ratchet pawls 66 engage with and jamagainst the lock faces 58 of the ratchet teeth 56 if an attempt is made to turn the thumbwheel 20in the opposite, prohibited direction.Figure 7 also shows that the tips of the ratchet pawls 66 are staggered, in other words spacedapart by a circumferential distance that is a non-integer multiple of the pitch of the ratchet teeth56. Thus, when the tip of one ratchet pawl 66 is engaged with a lock face 58 of a ratchet tooth 56,the tip of the other ratchet pawl 66 is mid-way along the ramp face 60 of another ratchet tooth56. As a result, a clinician feels and hears more frequent and finer clicks when turning thethumbwheel 20 and experiences greater precision of operation.In addition to its ratchet function, the ratchet hub 40 also has a locking function to lock thethumbwheel 20 selectively against rotation. For this purpose, the ratchet hub 40 furthercomprises an integrally-moulded locking member comprising a locking arm 68 that iscantilevered from the base plate 64 on the same face as the ratchet pawls 66, hence also facinginto the recess of the thumbwheel 20.The locking arm 68 is resiliently biased out of the plane 18 of the base plate 64, hence bendingabout an axis that is generally parallel to that plane 18. Under that bias, an integral locking pawl70 at the free end of the locking arm 68 engages with one of the notches 62 in the central web 52of the thumbwheel 20. That engagement locks the thumbwheel 20 against any rotation.The locking arm 68 further comprises an integral cam formation 72 near its free end. A slot 74that penetrates the base plate 64 accommodates the cam formation 72, which thereby protrudesfrom the face of the base plate 64 opposed to the ratchet pawls 66 and the locking arm 68. Thecam formation 72 diverges from the base plate 64 in the distal direction.As will be explained, the thumbwheel 20 is unlocked by proximal movement of the detentelement 42 relative to the housing 16, The detent element 42 will therefore be described nowwith reference to Figure 8.The detent element 42 is an elongate integrally-moulded component that comprises, in distalsuccession from the proximal end: a proximal yoke 76; a latch formation comprising a pair ofresilient wings 78; and a distal pawl 80.The yoke 76 of the detent element 42 comprises a loop 82 of an elongated, longitudinally-extending stadium shape. The loop 82 fits into a complementary groove 84 formedlongitudinally in the housing 16, as can be seen in Figures 2 and 3. The groove 84 is longer thanthe loop 82 to allow the detent element 42 to move proximally relative to the housing 16 into afinishing, unlocked position shown in Figure 3 from a starting, locked position in which the loop82 is at the distal end of the groove 84, as shown in Figure 2. The groove 84 also surrounds theaforementioned slot 22 through which the thumbwheel 20 protrudes from the housing 16. Thus,the protruding part of the thumbwheel 20 also protrudes through the loop 82.A skirt 86 on the underside of the yoke 76 extends into the slot 22 in the housing 16. Retainingflanges 88 projecting outwardly from the skirt 86 engage the wall of the housing 16 around theslot 22 while allowing the yoke 76 to slide longitudinally within the surrounding groove 84.The skirt 86 of the yoke 76 is interrupted by a cut-out 90. On the distal side of the cut-out 90, theskirt 86 tapers proximally to define an outwardly-facing ramp surface 92 that is inclinedinwardly from the outer side of the skirt 86 toward the inner side of the skirt 86. On its sideopposed to the cut-out 90, the skirt 86 of the yoke 76 also has a curved elongate recess 94 thataccommodates the spool 36 attached to the thumbwheel 20.Referring now also to Figures 9a, 9b and 10, Figure 9a shows the loop 82 of the yoke 76 in itsdistal starting position whereas Figures 9b and 10 show the loop 82 in its proximal finishingposition. It will be apparent that the cut-out 90 in the skirt 86 accommodates the cam formation72 that protrudes from the base plate 64 of the ratchet hub 40, and that the cam formation 72thereby lies in the path of the ramp surface 92 of the skirt 86 as the yoke 76 moves proximally.In the distal starting position of the yoke 76 shown in Figure 9a, the ramp surface 92 of the skirt86 lies distally with respect to the cam formation 72 of the ratchet hub 40 and is not yet engagedwith the cam formation 72. Conversely, in the proximal finishing position of the yoke 76 shownin Figures 9b and 10, the ramp surface 92 has moved proximally into engagement with the camformation 72. This engagement between the opposed sliding surfaces of the ramp surface 92 andthe cam formation 72 deflects the locking arm 68 of the ratchet hub 40 against its resilient biasto pull the locking pawl 70 clear of the notches 62 in the central web of the thumbwheel 20,which frees the thumbwheel 20 for rotation.The loop 82 of the yoke 76 has an outward protrusion serving as a thumb grip 96 at its distalend, aligned on the central longitudinal plane 18 with the distal end of the protrudingthumbwheel 20. A clinician can simply press a thumb against the distal side of the thumb grip 96to slide the detent element 42 proximally. This action unlocks the thumbwheel 20 forunidirectional rotation as described above. Elegantly, the thumbwheel 20 can then be turned bycontinued proximal movement of the thumb after sliding the thumb across the top of the thumb grip 96. These thumb movements are intuitive and simple to perform, yet distinct and deliberate enough to avoid unintended deployment of an implant.Returning to Figure 8, a central spine 98 of the detent element 42 extends distally from a distalend of the yoke 76 on an axis that is offset from, but generally parallel to, the plane 18 of theskirt 86. That offset allows the spine 98 to be accommodated within the distally-tapering distalportion of the housing 16.The resilient wings 78 extend laterally from and converge proximally with a proximal portion ofthe spine 98. The wings 78 form part of a one-way or unidirectional latch mechanism whoseoperation will be described later with reference to Figures 13a and 13b. The spine 98 also has adistal portion that is joined integrally to the proximal portion by a flexure such as a live hinge 100. The hinge 100 is formed by a transverse band of reduced thickness between the proximal and distal portions of the spine 98.The spine 98 terminates distally in guide arms 102 that extend laterally from the distal end ofthe distal portion and in the distal pawl 80 that comprises a central strut 104 and a laterally-extending cross-bar 106 in a hammerhead configuration. The central strut 104 is inclinedrelative to the distal portion of the spine 98 about an axis that is orthogonal to the centrallongitudinal plane 18. By virtue of the inclination of the central strut 104, the cross-bar 106 canengage the outer sheath adaptor 32 when the detent element 42 is in its distal starting position.In this respect, reference is now also made to Figures 11a, 11b and 12. Figures 11a and 12 showthe detent element 42 in its distal starting position. Here, the cross-bar 106 is engaged on itsdistal side with a proximal shoulder 108 of the outer sheath adaptor 32 and on its proximal sidewith stop formations or bosses 110 that are moulded integrally within the two parts of thehousing 16. In this way, the cross-bar 106 of the distal pawl 80 locks the outer sheath 26 directlyagainst proximal movement, instead transferring proximal loads into the detent element 42 andthe housing 16 of the handle 14. As best appreciated in Figures 8 and 12, the cross-bar 106 has acentral notch 112 to accommodate the pull wire 34 connected to the outer sheath adaptor 32.Conversely, Figures 10 and 11b show the detent element 42 in its proximal finishing positionwith the cross-bar 106 of the distal pawl 80 pulled away and disengaged from the outer sheathadaptor 32 and the bosses 110. This movement of the distal pawl 80 is due to tension applied tothe spine 98 by proximal movement of the yoke 76. Thus, on being moved proximally to unlockthe thumbwheel 20 by interacting with the ratchet hub 40, the detent element 42 also releasesthe outer sheath 26 for proximal movement when a clinician subsequently operates thethumbwheel 20.Guide formations 114 within the housing 16 engage the guide arms 102 that extend laterallyfrom the distal end of the spine 98 to guide movement of the cross-bar 106 when it is beingdisengaged from the outer sheath adaptor 32 and the bosses 110. As best appreciated in Figures10 to 12, the guide formations 114 comprise parallel flanges that are integrally moulded withthe two parts of the housing 16. The guide formations 114 receive the outer ends of the guidearms 102 in a gap between them. That gap defines a guide path 116 for the guide arms 102 tofollow in response to proximal movement of the detent element 42.The guide path 116 defined by the guide formations 114 does not merely extend in a proximaldirection, parallel to the sliding movement of the yoke 76. Instead, a distal segment of the guide path 116 is acutely angled transverse to the proximal direction. Thus, the guide formations 114serve as a cam ramp so that proximal movement of the yoke 76 applies mechanical advantage topull the cross-bar 106 away from the outer sheath adaptor 32 and the bosses 110.Once the cross-bar 106 is clear of the retraction path of the outer sheath adaptor 32, the guidearms 102 then enter a proximal segment of the guide path 116 that is substantially parallel tothe sliding movement of the yoke 76. Movement of the guide arms 102 along the distal segmentof the guide path 116 followed by their entry into the proximal segment of the guide path 116 isfacilitated by bending of the live hinge 100 between the proximal and distal portions of the spine 98.Figures 13a and 13b illustrate the aforementioned unidirectional latch mechanism thatcomprises the proximally-converging wings 78 extending laterally from the proximal portion ofthe spine 98. Inwardly-facing lugs 118 are moulded integrally within the two parts of thehousing 16 in mutual opposition about the central longitudinal plane 18. The lugs 118 divide adistal compartment 120 of the latch mechanism from a proximal compartment 122 of the latchmechanism.When the detent element 42 is in its locked, distal starting position as shown in Figure 13a, thewings 78 lie in the distal compartment 120. When the detent element 42 is then moved into itsunlocked, proximal finishing position as shown in Figure 13b, the resilient wings 78 deflectinwardly around the lugs 118 and then snap back outwardly when they enter the proximalcompartment 122.The deflection of the wings 78 imparts initial resistance to movement of the detent element 42,hence requiring that movement to be a deliberate release movement on the part of a clinician.The snap-back action of the wings 78 then provides audible and tactile confirmation to theclinician that the detent element 42 has reached its unlocked position and that the thumbwheel20 is therefore now free to be turned to deploy an implant.On entering the proximal compartment 122, the distal tips of the wings 78 bear against theproximal side of the lugs 118 to prevent distal movement of the detent element 42 back to thelocked starting position. This therefore prevents any attempt a clinician might make to interruptand resume deployment of the implant after re-locking the device 10. The irreversible proximalposition of the yoke 76 also indicates, and prevents concealment of, any accidental prematureoperation of or deliberate tampering with the device 10. If a clinician chooses a device 10 inwhich the detent element 42 is not in its locked distal position, the clinician can be instructed todiscard that device 10 and to choose another device 10 that is clearly locked and ready for itssingle use.The schematic drawings of Figures 14a to 20b illustrate alternative detent mechanisms forlocking the outer sheath 26 of an implant deployment device 10. Like numerals are used for likefeatures, but details such as the pull wire 34 that acts on the outer sheath adaptor 32 to retractthe outer sheath 26 have been omitted for clarity.In the mechanism of Figures 14a and 14b, a pivoting lock element 124 bears against the outersheath adaptor 32 to block its proximal movement when the detent element 42 is in the distallocked position as shown in Figure 14a. In that starting position, a distal end of the detentelement 42 engages a slot 126 in the lock element 124 to stop the lock element 124 pivotingaway from the outer sheath adaptor 32. When the detent element 42 is slid proximally into itsfinishing position as shown in Figure 14b, the distal end of the detent element 42 disengagesfrom the slot 126 to allow the lock element 124 to pivot away from the outer sheath adaptor 32.The outer sheath 26 can then slide proximally along the inner sheath 24 when the thumbwheel20 is turned, causing the outer sheath adaptor 32 and the outer sheath 26 to move proximallypast the lock element 124.In the mechanisms shown in Figures 15a to 17b, a distal pawl 128 of the detent element 42bears against a proximal shoulder 108 of the outer sheath adaptor 32 to block proximalmovement of the outer sheath 26 as shown in Figures 15a, 16a and 17a. A proximal stopformation 130 holds the distal pawl 128 of the detent element 42 against the outer sheathadaptor 32. Proximal movement of the detent element 42 relative to the stop formation 130, asshown in Figures 15b, 16b and 17b, causes a distal portion of the detent element 42 to deflectaround the stop formation 130, hence disengaging the distal pawl 128 from the outer sheathadaptor 32. Resilient straightening bias of the detent element 42 then swings the distal pawl 128away from the outer sheath adaptor 32, freeing the outer sheath 26 to slide proximally along theinner sheath 24 when the thumbwheel 20 is turned.In Figures 15a and 15b, the distal portion of the detent element 42 is joined to the remainder ofthe detent element 42 by a live hinge 132. Also, the distal portion of the detent element 42 has aprotrusion 134 with a proximally-facing surface that is arranged to bear against the stopformation 130 when the detent element 42 is in the distal locked position shown in Figure 15a.Proximal movement of the detent element 42 as shown in Figure 15b disengages the protrusion134 from the stop formation 130 in addition to disengaging the distal pawl 128 from theproximal shoulder 108 of the outer sheath adaptor 32. In the mechanisms of Figures 16a and 16b and Figures 17a and 17b, the stop formation 130 has a ramp shape that complements, respectively, curved and inclined distal portions of the detentelement 42. Proximal movement of the detent element 42 as shown in Figures 16b and 17bdisengages the distal pawl 128 from the proximal shoulder 108 of the outer sheath adaptor 32.Flexing of the detent element 42 caused by the ramp shape of the stop formation 130 thendeflects the distal portion away from the retraction path of the outer sheath adaptor 32.In the mechanisms shown in Figures 18a to 19b, the detent element 42 acts on a pivoting lockelement 124 that is joined to a distal end of the detent element 42 by a live hinge 132. When thedetent element 42 is in its distal locked starting position as shown in Figures 18a and 19a, adistal pawl 128 of the lock element 124 engages a proximal shoulder 108 of the outer sheathadaptor 32. Proximal movement of the detent element 42 as shown in Figures 18b and 19bpivots the lock element 124 to lift the distal pawl 128 out of engagement with the outer sheathadaptor 32 to free the outer sheath 26 to slide proximally along the inner sheath 24 when thethumbwheel 20 is turned.The pivoting lock element 124 of Figures 18a and 18b is generally L-shaped and is pivotedbetween the limbs of the L shape. The distal end of the detent element 42 is joined to the lockelement 124 at an end of one of the limbs, and the distal pawl 128 of the lock element 124 is atan end of the other of the limbs. When the detent element 42 is in its distal locked startingposition as shown in Figure 18a, the distal pawl 128 of the lock element 124 bears against theproximally-facing shoulder 108 of the outer sheath adaptor 32. Pivoting the lock element 124 byproximal movement of the detent element 42 as shown in Figure 18b lifts the distal pawl 128 ofthe lock element 124 out of engagement with the outer sheath adaptor 32. The pivoting lock element 124 of Figures 19a and 19b is generally triangular and is pivoted about a first corner of the triangle. The distal end of the detent element 42 is joined to thetriangle at a second corner of the triangle, whereas the distal pawl 128 of the lock element 124 isat a third corner of the triangle. When the detent element 42 is in its distal locked startingposition as shown in Figure 19a, the distal pawl 128 of the lock element 124 protrudes between,and so is sandwiched by, a fixed distally-facing stop formation 130 and the proximally-facing shoulder 108 of the outer sheath adaptor 32. Pivoting the lock element 124 by proximalmovement of the detent element 42 as shown in Figure 19b pulls the distal pawl 128 of the lockelement 124 out of engagement with the stop formation 130 and the outer sheath adaptor 32.Turning finally to Figures 20a and 20b, the detent element 42 shown here comprises segments136 that are joined in series by live hinges 132. When the detent element 42 is in its distallocked starting position as shown in Figure 20a, a distal one of the segments 136 is received in aslot 138 defined between stop formations 130. In that slot 138, the distal segment 136 is heldagainst the proximally-facing shoulder 108 of the outer sheath adaptor 32 to prevent proximalmovement of the outer sheath 26. Proximal movement of the detent element 42 pulls the distalsegment 136 out of the slot 138 and therefore out of engagement with the outer sheath adaptor32 as shown in Figure 20b. The live hinges 132 allow the segments 136 of the detent element 42to follow a curved path away from the retraction path of the outer sheath adaptor 32, aided by resilient straightening bias of the detent element 42.

Claims

Claims1. An implant deployment device comprising a delivery tube and a handle at a proximal end ofthe delivery tube, wherein the handle comprises: a control element that is movable relative to a housing of the handle to move a deployment component of the delivery tube to an extent sufficient to deploy an implantfrom the delivery tube; anda detent element that acts separately on the control element and on the deployment componentand is movable relative to the housing from a locked position in which movement of the controlelement and the deployment component is blocked to an unlocked position in which movementof the control element and the deployment component is permitted. The device of Claim 1,wherein the control element and the detent element are located so as to operate respectively with one thumb.

2. The device of Claim 1, comprising a locking member that is engaged with the control elementwhen the detent element is in the locked position and that is disengaged from the controlelement by movement of the detent element into the unlocked position.

3. The device of Claim 2, wherein the locking member is biased into engagement with the control element and is disengaged from the control element against that bias.

4. The device of Claim 3, wherein the locking member comprises a locking arm that supports alocking pawl and the locking pawl is biased into engagement with the control element byresilience of the locking arm.

5. The device of Claim 4, wherein the locking pawl is supported by a ratchet hub that restricts the control element to unidirectional movement.

6. The device of any of Claims 2 to 5, wherein the locking member and the detent element haveopposed sliding surfaces that interact with a cam action during said movement of the detentelement, to disengage the locking member from the control element.

7. The device of any preceding claim, further comprising a unidirectional latch mechanism that isarranged to block movement of the detent element back from the unlocked position to thelocked position.

8. The device of Claim 7, wherein the latch mechanism comprises latch formations on the detent element that are resiliently deflectable around lugs fixed relative to the housing.

9. The device of Claim 8, wherein the latch formations are unable to deflect back around the lugsafter the detent element reaches the unlocked position.

10. The device of any preceding claim, wherein the detent element comprises a proximal portionexposed outside the housing in a position adjacent to the control element and a distal portionwithin the housing acting on the deployment component.

11. The device of Claim 10, wherein the exposed proximal portion of the detent element comprises a grip protrusion that is disposed distally of the control element and is substantially aligned with the control element in a central longitudinal plane of the housing.

12. The device of Claim 10 or Claim 11, wherein the detent element is movable proximallyrelative to the housing into the unlocked position and the control element is then movable proximally relative to the housing to deploy the implant.

13. The device of any preceding claim, wherein the detent element comprises a distal pawl that,when the detent element is in the locked position, is engaged with an adaptor that is disposedwithin the housing and is fixed to the deployment component.

14. The device of Claim 13, wherein when the detent element is in the locked position, the distalpawl is engaged between the adaptor and an opposed stop formation of the housing.

15. The device of Claim 13 or Claim 14, comprising a guide formation that defines a guide path tobe followed by the distal pawl, that guide path being initially transverse to a direction ofmovement of other parts of the detent element into the unlocked position.

16. The device of Claim 15 when dependent upon Claim 14, wherein the stop formation alsoserves as the guide formation.

17. The device of Claim 15 or Claim 16, wherein the detent element comprises a flexure thatallows the distal pawl to move relative to the other parts of the detent element when followingthe guide path.

18. The device of any of Claims 13 to 17, wherein the distal pawl is engaged with the adaptoragainst resilient bias of the detent element, to move clear of the deployment component underthat bias when disengaged from the adaptor.

19. The device of any of Claims 1 to 12, wherein on being moved into the unlocked position, the detent element disengages from a locking member that previously blocks movement of thedeployment component and thereby releases the locking member to move aside, releasing thedeployment component for movement.

20. The device of any of Claims 1 to 12, wherein on being moved into the unlocked position, thedetent element pivots a locking member that previously blocks movement of the deploymentcomponent to release the deployment component for movement.

21. The device of any preceding claim, wherein the control element is a thumbwheel that can be turned to tension a pull element connected to the deployment component, hence retracting the deployment component proximally to deploy the implant.

22. The device of Claim 21, wherein the pull element is wound onto a spool that is coaxial with the thumbwheel about a common axis of rotation and is offset along that axis from the thumbwheel.

23. The device of Claim 22, wherein the pull element follows a path that comprises a first legextending proximally from the deployment component to a pulley disposed proximally withinthe handle with respect to the spool, and a second leg extending distally from the pulley to the spool.

24. The device of Claim 23, wherein the pulley is oriented with respect to the handle such that anentry of the first leg of the pull element onto the pulley lies substantially in a common plane withthe thumbwheel and an exit of the second leg of the pull element from the pulley lies on thesame side of that plane as the spool.

25. The device of any preceding claim, wherein the control element and the detent element arelocated so as to be operable respectively with a thumb of a hand holding the handle.

26. A method of enabling an implant deployment device to deploy an implant from a deliverytube of the device, the method comprising moving a detent element on a handle of the devicefrom a locked position into an unlocked position, the detent element thereby releasing a controlelement of the handle and a deployment component of the delivery tube from respective locked states for respective deployment movements relative to a housing of the handle.

27. The method of Claim 26, comprising subsequently moving the control element to effect deployment of the implant by moving the deployment component of the delivery tube.

28. The method of Claim 27, comprising restricting said movement of the control element tounidirectional movement.

29. The method of any of Claims 26 to 28, comprising moving the control element in a directionof movement corresponding to a direction of movement of the detent element into the unlockedposition.

30. The method of Claim 29, comprising moving the detent element by applying proximal force to the detent element at a location distal to the control element, and then moving the controlelement by applying proximal force to the control element.

31. The method of any of Claims 26 to 30, comprising preventing movement of the detentelement back to the locked position from the unlocked position.

32. The method of any of Claims 26 to 31, comprising releasing the deployment component ofthe delivery tube by disengaging a distal pawl of the detent element from an adaptor that isdisposed within the housing and is fixed to the deployment component.

33. The method of Claim 32, comprising guiding the distal pawl on a path that is transverse to adirection of movement of other parts of the detent element into the unlocked position.

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