Stent crimping system

A stent crimping assembly is provided for crimping a stent from a first diameter to a reduced second diameter. The crimping assembly includes a plurality of movable wedges disposed about a rotational axis to form a wedge assembly. Each wedge includes a respective first side and a second side converging to form a tip portion. The tip portions are arranged to collectively form an iris about the rotational axis thereof. The iris defining a crimp aperture about which the movable wedges are disposed. Each wedge is associated with a stationary structure and an rotational actuation unit such that during rotation of the actuation unit about the rotational axis, the iris is caused to rotate about the rotational axis, relative the stationary structure, for inward movement of the wedges to decrease the size of the aperture and outward movement of the wedges to increase the size of the aperture.

FIELD OF THE INVENTION

The present invention relates generally to intraluminal devices, and more particularly relates to apparatus and methods for reducing the size of these devices, such as a stent, stent-graft, graft or vena cava filter, for percutaneous transluminal delivery thereof.

BACKGROUND OF THE INVENTION

A number of vascular diagnostic and interventional medical procedures are now performed translumenally. For example, catheter is introduced to the vascular system at a convenient access location and guided through the vascular system to a target location using established techniques. Such procedures require vascular access, which is usually established during the well-known Seldinger technique. Vascular access is generally provided through an introducer sheath, which is positioned to extend from outside the patient body, through a puncture in the femoral artery for example, and into the vascular lumen. Catheters or other medical devices are advanced into the patient's vasculature through the introducer sheath, and procedures such as balloon angioplasty, stent placement, etc. are performed.

In particular, stents and stent delivery assemblies are utilized in a number of medical procedures and situations, and as such their structure and function are well known. A stent is a generally cylindrical prosthesis introduced via a catheter into a lumen of a body vessel in a configuration having a generally reduced diameter for transport and delivery, and then expanded to a diameter of the target vessel when deployed. In its expanded configuration, the stent supports and reinforces the vessel walls while maintaining the vessel in an open, unobstructed condition.

Balloon expandable stents are well known and widely available in a variety of designs and configurations. Balloon expandable stents are crimped to their reduced diameter about the delivery catheter, then maneuvered to the deployment site and expanded to the vessel diameter by fluid inflation of a balloon positioned between the stent and the delivery catheter. One example of a stent is described in U.S. patent application having Publication No. 2004/0093073, published May 13, 2004, the content of which is incorporated herein by reference.

During advancement of the stent through a body vessel to a deployment site, the crimped stent must capable of securely maintaining its axial position on the delivery catheter. That is, the crimped stent must not translocate proximally or distally during advancement, and especially must not dislodge from the catheter. Stents that are not properly crimped, secured or retained to the delivery catheter may slip and will either be lost, be deployed in the wrong location or only be partially deployed. Moreover, the stent must be crimped in such a way as to minimize or prevent distortion of the stent, and thereby, minimize or prevent abrasion and/or trauma to the vessel walls. Additionally, if a stent has been coated with a beneficial agent, care must be taken when crimping the stent onto the delivery device that the coating is not disturbed or removed from the stent during the crimping process.

In the past, crimping has been performed by hand, often resulting in an undesirable application of uneven radial crimping forces to the stent. Such a stent must either be discarded or re-crimped. Stents that have been crimped multiple times can suffer from fatigue and may be scored or otherwise marked which can cause thrombosis. In fact, a poorly crimped stent can also damage the underlying balloon.

In addition to hand crimping of stents, automated crimping machines have been developed, wherein the automated crimping machines provide a more consistent crimp radial force during the crimping process or consistent profile. In addition to providing consistent crimping forces, many other crimping parameters can be closely controlled through the use of computer controls or mechanical controls. An example of such an automated crimping machine and related crimping methods can be seen in U.S. Pat. No. 6,629,350 to Motsenbocker. The crimping machine shown and described in the '350 patent includes a crimp head comprising a plurality of segments, wherein one end of each of the segments is constrained to rotate about a pin wherein the other end of the segments is allowed to translate about a second pin. In this arrangement, the translation of the second end of each of the segments controls the size of the opening formed by the distal ends of the segments. A shortcoming of such a design is wear of each of the segments at the pins. The increased wear increases the tolerances through which the crimp head can be operated, eventually the crimp head can no longer be held to a desired tolerance and therefore must be rebuilt. Thus there is a need for an improved crimp head design that can be held to tighter tolerances for a significant period of operation.

In addition to the balloon expandable stents described above, it would be desirable to provide a stent crimping system capable of loading (i.e., crimping) self-expanding stents into a delivery device, wherein the stent can be chilled during compression. Further still, once compressed into a delivery diameter, the crimped stent must then be inserted into a distal end of a delivery system while maintaining the delivery profile. In order to accomplish this, the crimping head must be constructed such that minimal friction exists between the stent and the head. Additionally, the delivery device must be retained relative to the crimping head and then advanced a known distance to insert the crimped stent, without damaging the delivery device.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and methods for mechanically crimping a generally tubular stent from a first diameter to a second diameter. A stent crimping assembly is provided that includes a plurality of movable wedges having respective first side and a second side converging to form a tip portion. The tip portions are arranged to collectively form an iris about a rotational axis thereof. The iris defines a crimp aperture about which the movable wedges are disposed. Each wedge is associated with a stationary structure and a rotational actuation unit such that during rotation of the actuation unit about the rotational axis, the iris is caused to rotate about the rotational axis, relative the stationary structure, for inward movement of the wedges to decrease the size of the crimp aperture and outward movement of the wedges to increase the size of the crimp aperture.

Accordingly, during the crimping procedure, the stent is also caused to rotate with the iris. When released, the partially or fully crimped stent will remain at least partially rotated relative to the initial position before a crimp. This is advantageous for any subsequently repeat crimp. Often, in a conventional crimping process, the crimp should be repeated several times in order to achieve a smaller profile and better and more uniform circularity. Each time, between operations, the stent or crimper should be rotated relative to each other to achieve this result. In the present invention, this rotational procedure automatically becomes part of the process, and hence the manual process of rotating the stent or crimper during the repeat crimp procedure can be eliminated.

In one specific embodiment, the movable wedges have at least one end section coupled to the stationary structure for relative rotational displacement therebetween, and another section of the movable wedge coupled to the actuation unit for substantially relative linear displacement therebetween. The rotational coupling of each wedge to the stationary structure is positioned proximate to a distal portion of the respective wedge, and the linear coupling of each wedge to the actuation unit is positioned proximate to a proximal portion of the respective wedge.

A further specific arrangement, the relative rotation displacement of each wedge is about a respective rotational axis that extends substantially parallel to the rotational axis of the iris. The relative linear displacement of each wedge is in a direction that extends substantially perpendicular to a respective bisecting plane of each wedge. The rotational coupling of each wedge to the stationary structure further includes a respective linear displacement along a respective bisecting plane of each wedge for movement toward the aperture during the inward movement thereof, and movement away from the aperture during the outward movement thereof.

Another embodiment includes the stationary structure with a stationary end wall that includes a plurality of bearing devices disposed about the rotational axis of the iris. Each bearing device is associated with one respective wedge, and each wedge end section defining the elongated slot extending in a direction along the respective centerline of the wedge.

In yet another specific embodiment, the actuation unit includes a housing enclosing the plurality of movable wedges. The housing rotatably couples the stationary end wall for rotational displacement about the rotational axis of the iris. A respective slider mechanism couples a respective wedge to the housing for the respective substantially linear displacement of the respective proximal portion of the wedge to the housing during the rotational displacement of the housing. The slider mechanism includes a linear bearing device mounted to the wedge, and a carriage unit slideably coupled to the bearing device for movement in a direction substantially perpendicular to respective bisector of the wedge.

In another aspect of the present invention, a stent crimper system includes an iris composed of a plurality of movable wedges disposed about an aperture. The iris includes a rotational axis about which the wedges rotate as a unit. The wedges are disposed between substantially concentric first end walls and an actuation housing substantially centered about the rotational axis and rotatably coupled to the first end walls. Each wedge is associated with the first end walls and the actuation housing such that during rotational movement of the actuation housing, the iris is caused to rotate about the rotational axis, relative a stationary structure, for inward movement of the wedges to decrease the size of the aperture and outward movement of the wedges to increase the size of the aperture.

In one specific embodiment, the first end walls are stationary end walls affixed relative to the stationary structure. In another arrangement, the actuation housing includes a pair of opposed rotational end walls rotatably coupled to a respective first end wall. Each of the rotational end walls and the first end walls are configured for rotational displacement, relative one another, about the rotational axis.

In still another aspect of the present invention, a crimping apparatus is disclosed for reducing the diameter of a medical device. The apparatus includes at least one end plate; at least one drive plate; and a crimping assembly. The crimping assembly includes a plurality of blades, wherein the blades have a proximal and distal end and a tapered portion adjacent the distal end. A pivot member is disposed on each side of each blade, and the pivot member is configured to be received by the drive plate. The blades further include a sliding assembly, a portion of the sliding assembly coupled to the blade adjacent the proximal end and a second portion of the sliding assembly coupled to the end plate.

In yet another aspect of the present invention, a stent crimping system is provided including a chassis, a crimping assembly, a clamping assembly and a control unit. The clamp assembly that secures the medical device includes a lower clamp device defining a seating groove formed and dimensioned to seat a portion of the medical device therein. A retaining assembly includes an elastomeric member, the elastomeric member defining a contacting groove oriented in an opposed manner proximate to at least a portion of the seating groove. An actuation mechanism is associated with the retaining assembly and the lower clamp device such that operation thereof causes the retaining assembly to move between an opened condition, enabling positioning of the elongated device between the lower clamp device and the retaining assembly, and a closed condition, retaining the medical device between the contacting groove of the elastomeric member and the seating groove of the lower clamp device.

In another specific embodiment, the clamp device includes a pivot lever rotatably mounted to the lower clamp device. The pivot lever cooperates between the actuation mechanism and the retaining assembly for movement of the retaining assembly between the opened condition and the closed condition.

The retaining assembly is coupled to the pivot lever proximal a distal portion of the lever member. Further, the actuation mechanism cooperates with the pivot lever proximal a proximal portion thereof such that when the actuation mechanism is moved from a first position towards a second position, the pivot lever is caused to rotated about a rotational axis of the pivot pin which causes the retaining assembly to move from the opened condition toward the closed condition.

In yet another specific embodiment, the lower clamp device includes a base portion and a support plate extend distally from the base portion. The seating groove extends along an upper edge portion thereof from the base portion to the support plate. The retaining assembly includes a pair of plate members mounted to, and depending downwardly, from the elastomeric member on opposite sides of the support plate. Each plate member is coupled to the pivot lever at the distal portion thereof.

The pivot lever includes a pair of lever portions disposed on opposite sides of the lower clamp device support plate. E lever portion is pivotally mounted to a corresponding plate member through a securing pin extending therethrough. The support plate includes an elongated slot upon which the securing pin passes therethrough. The elongated slot be configured to accommodate the travel of the securing pin as the retaining assembly reciprocates between the opened condition and the closed condition.

DETAILED DESCRIPTION

While the present invention will be described with reference to a few specific embodiments, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications to the present invention can be made to the preferred embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims. It will be noted here that for a better understanding, like components are designated by like reference numerals throughout the various figures.

Referring now toFIGS. 1-6, a stent crimping assembly, generally designated20, is illustrated that defines a crimp aperture21for crimping a stent (not shown) from a first diameter (FIG. 4) to a reduced second diameter (FIG. 5). This crimping assembly20includes a plurality of movable blades or wedges22arranged in an assembly25around the crimp aperture21. Each wedge, as best viewed inFIGS. 3 and 6, include a first side26and a second side27that converge to form a distal tip portion28. When assembled in the wedge assembly25, the first and second sides26,27of each wedge22are arranged substantially adjacent the second and first sides27,26, respectively, of an adjacent wedge22such that the tip portions28collectively form an iris30. The iris30defines the crimp aperture21centered about the iris rotational axis31. Hence, the distal portions of the wedges22are directed generally inwardly while the proximal portions of the wedges are directed generally outwardly.

As will be described in greater detail below, the crimping assembly20includes a stationary structure32and a rotational actuation unit33that is rotatably associated with the stationary structure for rotation of the unit about the iris rotational axis31. Each movable wedge22of the wedge assembly25is rotationally coupled to the stationary structure32proximate to a respective distal portion thereof such that each wedge22can rotate about a respective wedge rotational axis34thereof. Collectively, the wedge rotational axes34are radially spaced about the iris rotational axis31(FIG. 3). Each wedge rotational axis is oriented substantially parallel to, and circumferentially spaced-apart about, the iris rotational axis31. Further, a proximal portion of each wedge22is coupled to the actuation unit33through respective linear slider mechanisms36for substantially linear displacement relative to its coupling to the actuation unit. More particularly, as will be described the linear displacement is in a direction substantially perpendicular to a respective centerline or plane37bisecting the wedge22.

In accordance with the present invention, since the linear slider mechanisms36are collectively caused to rotate with the actuation unit33about the iris rotational axis31, each wedge22is caused to rotate about its wedge rotational axis34, while simultaneously sliding linearly (via the respective slider mechanism) relative to the rotating actuation unit33. Hence, the motion of the each wedge22relative a first end wall35′,35″ and the stationary structure32(as well as to the wedge rotational axis34which is fixed relative to the stationary structure) is represented in the single wedge trajectory diagram ofFIG. 8and the relative movement of the multiple wedges ofFIG. 9. Collectively, the iris30itself is caused to rotate as a unit about the iris rotational axis31, relative to the stationary structure32. This is advantageous in that the stent is also caused to rotate. When released, the partially or fully crimped stent will remain at least partially rotated relative to the initial position before a crimp. Often, in a conventional crimping process, the crimp should be repeated several times in order to achieve a smaller profile and better and more uniform circularity. Each time, the stent or crimper should be rotated between these operations relative to each other to achieve this result. In the present invention, this rotational procedure automatically becomes part of the process, and hence the manual process of rotating the stent or crimper during the repeat crimp procedure can be eliminated.

Accordingly, in operation, when the actuation unit33is rotated about the iris rotation axis, in a counter-clockwise direction shown inFIGS. 1,4to the position ofFIG. 5(which illustrates the crimping assembly20with most of the actuation unit removed), the counter-clockwise motion is translated into both rotational movement of each respective wedge about its wedge rotational axis34, while further simultaneously displacing each wedge linearly inward along the respective slider mechanism. The linear displacement, for each slider mechanism36, is in a direction substantially perpendicular to a respective plane bisecting the each wedge22. As the entire iris30rotates relative to the stationary structure32, the inward sliding movement of the wedges22causes the aperture21to decrease in size. As the crimp aperture21closes (FIG. 5), a radially inward force, as well as a counter clockwise rotational force, is applied by the blades to the medical device (e.g., a stent) disposed in the aperture.

The actuation unit is rotated until the desired size reduction of the aperture and medical device is achieved. Subsequently, the actuation unit33is rotated in the oppose direction to permit removal of the device from the crimp aperture.

Turning now toFIGS. 6 and 7, a blade or wedge22of the crimping assembly is shown and illustrated as having a wedge shape that is generally symmetrical about the respective centerline or bisecting plane37thereof. In this specific embodiment, the wedge22includes an elongated hollow frame structure having an inwardly tapered distal end and a widened proximal portion with a substantially planar proximal end38. Preferably, the aforementioned first side26and the opposed second side27are substantially planar, and taper inwardly to form a straight tip portion (thus forming a substantially polygonal crimp aperture21). The distal end of the first side26, however, may be slightly curved toward crimp aperture (not shown), so as to form a more circular-shaped aperture when the crimp aperture is fully closed or reduced in size. Further, the tip portion may also terminate at a sharp edge. Preferably, however, the edge is slightly rounded or beveled, eliminating a sharp tip. This configuration facilitates sliding contact with the adjacent blade surfaces. Briefly, while the present invention has been shown and described as providing sliding, abutting contact between the wedge side walls, it will be appreciated that there may be some clearance therebetween with no sliding contact.

Depending upon the number of blades selected to form the iris30, the converging angle between the first side26and the second side27(i.e., the tip angle α) can be selected accordingly. For example, the wedge assembly may include as little as three wedges, and as many as sixteen. The maximum number of wedges is limited by the number thereof that can be physically coupled together under the relevant size constraints. As the number of blades is increased, the profile of the aperture and of thus of the crimped medical device becomes smoother. In the embodiment illustrated inFIGS. 1-5, twelve wedges22are employed where the first side26and the second side27of each blade are in substantially adjacent one another, or in sliding contact with the second side27and the first side26, respectively, of the adjacent blades. Generally the tip angle α is less than or equal to 360/n where n is equal to the number of blades. For the twelve-blade embodiment illustrated, the tip angle α is in the range of about 30 Degrees or less.

As best illustrated inFIG. 6, each wedge22is further defined by a substantially planar first end section40′ and an opposed substantially planar second end section40″. Each face of the end section defines an elongated bearing slot (41′,41″) extending substantially in a direction along the centerline37that bisects each wedge. Each bearing slot of the set (41′,41″) is further aligned relative to one another, and is positioned proximate to the distal portion of the wedge22.

The wedges22may be constructed of a material or a combination of materials such as nylon, delrin, steel, aluminum, titanium, TEFLON®, plastics, composite materials, and other suitable materials. This hollow framing of the wedge22also may be constructed of multiple pieces that may be assembled to form a unitary member, or alternatively each wedge22may be constructed as a unitary member. In another specific embodiment, each wedge22may include a replaceable blade insert42at each distal end thereof. At a distal portion of each wedge22, the first side26thereof defines a step or shoulder portion39formed to seat the elongated blade insert42therein (FIG. 7). In this arrangement, one side of the blade insert42seats substantially flush with the first side26of the wedge, while an opposed side of the blade insert seats substantially flush with the second side27. Accordingly, the entire contacting surface that is employed to crimp a stent may be provided by these replaceable blade inserts42. Such blade inserts42, by way of example, may also be composed of nylon, delrin, TEFLON®, plastics, composite materials, and other suitable materials. Such material selections depend in part upon the material properties, such as the thermo insulation, the thermo conductivity, whether the friction therebetween is low or high, etc.

In accordance with one embodiment of the present invention, the first end walls35′,35″ are substantially stationary, and are part of and mounted to stationary structure32. These stationary end walls (i.e., a proximal end wall35′ and a distal end wall35″) are disposed at opposite ends of the wedge assembly25. Preferably, these stationary end walls35′,35″ each include an exterior surface and an opposed interior face43that is to be oriented to face inwardly toward the wedge assembly when assembled. A receiving port45extends therethrough from the exterior to the interior face43to that provides access to the crimp aperture21. Each end wall35′,35″ includes a respective hub portion46that is oriented to face inwardly, toward the wedge assembly25, during operation and assembly of the crimping assembly20. The stationary end walls35′,35″ each further include a mounting flange47that extends radially outward from the hub portion46.

FIGS. 1 and 10best illustrate that the stationary structure32further includes a support base48and a pair vertical supports50′,50″ upstanding therefrom. Each vertical support50′,50″ is substantially rigidly mounted to the respective end wall mounting flange47to secure the end walls35′,35″ in a stationary manner. It will be appreciated, of course, that the stationary end walls may be rigidly supported through any other conventional technique as well.

To rotatably support the assembly25of wedges22to the stationary structure32, each wedge22is rotatably coupled, at the opposed end sections40′,40″ thereof, to the corresponding stationary end wall35′,35″ for rotation about a respective wedge rotational axis34. As best illustrated inFIGS. 2-5and10, such rotational support is provided by a plurality aligned bearing devices51disposed at the opposed end sections40′,40″ of each wedge22. Each respective pair of bearing devices51cooperate to define the respective wedge rotational axis34about which each wedges individually rotates. To mount the wedge, assembly25, the bearing device pairs are affixed to the interior face43of the hub portions46of the stationary end walls35′,35″ and configured rotatably cooperate with, and support, the respective wedges22.

Briefly, each bearing device51includes a pivot shaft52having a pin end53suitable for affixed mounting into the interior face43of the respective hub portion46(FIGS. 4,5and10). These pin ends53may be friction fit, threaded or adhered to the interior face43in any secure manner. The pivot shaft52on the interior face43of the proximal stationary end wall35′ is to be co-axially aligned with the pivot shaft52on the interior face43of the distal stationary end wall35″ so that the respective wedge rotational axis34is substantially parallel to the iris rotational axis31.

Rotatably mounted to each pivot shaft52is a corresponding wheel55(flange) rotatably supported about the shaft through ball bearings or the like. These wheel flanges55and pivot shafts52of the bearing devices are configured for receipt in the corresponding bearing slots41′,41″ defined by the first and second end sections40′,40″ of the respective wedge.

As illustrated, each bearing device51is aligned with its corresponding bearing on an opposite end of the wedge assembly. Collectively, these bearing pairs are equally spaced apart radially about the iris rotational axis, thus also positioning the wedge rotational axes34equally spaced apart radially about the iris rotational axis. Moreover, these radially spaced wedge rotational axes34are oriented substantially parallel to the iris rotational axis31, which center the rotation of the iris30about the iris rotational axis31. Accordingly, during operational movement, the respective wedge rotational axes34of the wedge assembly25remain stationary relative the stationary end walls35′,35″, while each respective wedge22simultaneously rotates about its wedge rotational axis, and slides substantially linearly a direction substantially perpendicular to the respective centerline37of the respective wedge22.

In order to permit such linear sliding displacement in the aforementioned direction, each wedge22themselves must also be capable of sliding linearly along the respective bearing devices in a direction along the centerline plane. The bearing slots41′,41″, each of which extend in a direction along the centerline plane, accommodate this motion.

Therefore, these bearing couplings not only promote relative rotation of the wedges22about the respective wedge rotational axis34, via the wheel flanges55, but also promote linear displacement along the respective bearing slot41′,41″ generally toward and away from the iris rotational axis. The width of the bearing slot, therefore, is sufficiently larger than the diameter of the corresponding wheel flange55to permit such sliding linear displacement along the elongated bearing slot as well as to promote rotation of the respective wedge22about the respective wedge rotational axis34. The tolerance between the slot width and the wheel (flange) diameter, however, must also be sufficiently small to reduce and minimize instability and chatter during operation.

In contrast, the length of the elongated bearing slots41′,41″ must be sufficient to permit the relative linear displacement of wheel flange55along the slot. This linear displacement essentially translates into movement of the rotating wedges22respectively toward and away from the crimp aperture21.

While the present invention has been illustrated and described as having the bearing slots defined by the end sections40′,40″ of the wedges22, and the bearing devices51mounted directly to the hub portions46of the stationary end walls35′,35″, it will be appreciated such mounting componentry can be easily reversed. In such a configuration, therefore, the bearing devices51can be mounted to the wedge end sections40′,40″, while the bearing slots will be defined by the interior wall of the hub portion46. In this arrangement, however, respective the bearing slots41′,41″ will not be substantially linear, and will shaped to substantially mirror the path of the wedge and wedges shown in the diagrams ofFIGS. 8 and 9.

Referring back toFIG. 1, a rotational actuation unit33is rotatably mounted to the stationary structure32to actuate the rotation of the wedge assembly25about the iris rotational axis31, and to cause the increase or decrease of the diameter of the iris30. Briefly, as above-mentioned, the actuation unit33is rotatably coupled to the stationary end walls35′,35″ for rotation the iris rotational axis31, while simultaneously individually coupled to the proximal portions of the respective wedges22for substantially linear displacement therebetween.

In one specific embodiment, the actuation unit33is provided by a housing structure that at least partially encloses the cylindrical wedge assembly25therein.FIGS. 1 and 10best illustrate that the rotational actuation unit33includes a pair of rotational end walls (i.e., a proximal rotational end wall56′ and the distal rotational end wall56″) that rotatably cooperate with the corresponding stationary end walls35′,35″, respectively, for rotational support. These rotational end walls56′,56″ are disposed on the opposed ends of the wedge assembly25, and are rotatably coupled to the hub portions46of the stationary end walls35′,35″ through respective rotational bearings57.

Hence, each plate-like rotational end wall56′,56″ defines a central bearing aperture58that is centered about the iris rotational axis, when rotatably supported to the respective hub portion46. This bearing aperture58is defined by an inward facing mounting surface60of the rotational end walls56′,56″ that, when centered, opposes an outward facing mounting surface61of the respective stationary end wall35′,35″. As shown inFIG. 10, the rotational bearing57, such as for example a conventional ball bearing assembly, is disposed between these mounting surfaces60,61to provide rotational support of the respective rotational end walls56′,56″ about the corresponding stationary end walls35′,35″. These bearing units57, hence, provide the primary rotational support of the actuation unit33about the iris rotation axis.

It will be appreciated, however, that such a ball bearing unit can be eliminated and a more direct bearing-style contact could be employed between the inward facing mounting surface60of the rotational end walls56′,56″ and the outward facing mounting surface61of the respective stationary end wall35′,35″.

Further, it will be contemplated that the first end walls35′,35″ (i.e., the stationary end walls when affixed to the stationary structure32) may also rotatably coupled to the stationary structure for rotation about the aperture rotational axis. In this instance, both the rotational end walls56′,56″ may be mounted to rotational support structure to enable relative rotation therebetween, and relative to the stationary structure32, wherein the cross-support structure62(FIG. 11) would be supported by a rotatable member such as bearings (not shown). In this embodiment, the end walls35′,35″,56′ and56″ would be configured to move either independent of each other or in conjunction with each other, the cross-support structure62being rotationally coupled to the stationary structure32.

To rigidify the actuation units, so as to operate as a single unit, a cross-support structure62laterally extends from the proximal rotational end wall56′ to the distal rotational end wall56″. Generally, in one specific arrangement, this support structure62may be provided by a plurality of cross-beams that extend laterally across the wedge assembly25.FIG. 16best illustrates such a configuration where the cross-beams140extend across the wedge assembly, and are spaced-apart circumferentially about the aperture.

In the preferred embodiment of this specific arrangement, however, the cross-support structure62is provided by a unitary cylindrical-shaped drum portion63(FIG. 11). As shown inFIGS. 1 and 10, this unitary drum rigidly mounts the proximal rotational end wall56′ to the distal rotational end wall56″, together as a unit. This cylindrical-shaped housing structure is sized and dimensioned to essentially fully enclose the entire wedge assembly25therein without impeding movement of the wedges during rotational movement of the actuation unit33.

A handle member65can be mounted to the actuation unit33for rotational actuation of the unit about the iris rotational axis31. As illustrated inFIG. 1, a single handle member65can be mounted to the proximal rotational end wall56′ for manual rotation thereof. It will be appreciated, however, that such handle member can be mounted to either or both rotational end walls56′,56″, as well as to the drum portion63. Moreover, as will be described in greater detail below, conventional automated controls can be incorporated as well to automate the actuation movement.

In accordance with the present invention, a proximal portion of each wedge22is slideably coupled to the actuation unit33, via the slider mechanisms36, to promote substantially linear displacement of the wedge relative to the actuation unit. Each slider mechanism36is preferably disposed between the actuation unit33and the proximal portion of the respective wedge, in a manner permitting substantially linear sliding displacement in a relative direction, substantially perpendicular to the respective centerline or bisecting plane37of the respective wedge22. As mentioned above, this simultaneous, respective linear wedge displacement occurs as the entire wedge assembly25is rotating about the iris rotational axis31as a unit, and as the wedges further rotate about their respective wedge rotational axis34.

In one specific embodiment, the slider mechanisms36include a pair of spaced-apart substantially linear bearings66mounted to the respective wedge22, and a pair of corresponding carriage units67coupled to the actuation unit33. These carriage units67are configured to track linearly along the associated linear bearing66. In particular, as best viewed inFIG. 7, the two rails or linear bearing66are seated and affixed in a pair of corresponding alignment grooves69recessed the surface of the substantially planar proximal end38of each respective wedge22. These alignment grooves69orient the respective linear bearing66so that the corresponding carriage units67, in sliding contact therewith, will slide a substantially linear direction substantially perpendicular to the respective centerline of the wedge.

The carriage units67are generally U-shaped having a substantially planar outer surface, and a receiving slot68on an opposed surface that faces inwardly toward the respective wedge22. These receiving slots68are formed and dimensioned of sliding receipt of the corresponding linear bearing66therein for linear displacement of the carriage unit67therealong.

While the application of the pair of spaced-apart linear bearings66is preferred for stability and alignment, it will be appreciated that a single linear bearing or more than two bearing can be employed without departing from the true nature and scope of the present invention.

The crimping assembly20further includes a plurality of saddle units that fixedly mount each pair of carriage units67to the actuation unit33. Each saddle unit70is configured to seat in a corresponding access port71extending through the drum portion63. These access ports71are equally spaced circumferentially about the drum portion63, and provide mounting access to the corresponding carriage units67.

Each saddle unit70includes a base portion72and a pair of opposed mounting flanges73that seat against and mount to a corresponding shoulder portion75in each access port71(FIG. 10), via fasteners. In turn, a substantially planar interior facing surface of each saddle unit70abuts against and is aligned with the substantially planar outer facing surface of the respective pair of carriage units67. Using access cavities76, the respective saddle unit70can be secured to the respective pair of carriage units67, which in turn rigidly secure the carriage units to the actuation unit33.

Accordingly, referring back toFIGS. 4 and 5, as the actuation unit33is rotated as a unit in a counterclockwise direction about the iris rotational axis31, the wedge assembly25is also caused to rotate as a unit about the iris rotational axis31in the counterclockwise direction. Due to the intercoupling between the rotating actuation unit33and the stationary structure32, the rotational motion is partially translated to linear motion of the slider mechanisms36as the respective carriage units67are caused to slide along their respective linear bearings66. Consequently, the respective wedges22are then caused to rotate about their respective wedge rotational axis34at the respective pair of bearing devices51. Simultaneously, the wedges are caused slide inwardly toward the crimp aperture21as the respective wheel flanges55of the bearing devices51navigate along the corresponding bearing slots41from an interior end to an exterior end thereof. Hence, the diameter of the crimp aperture21decreases in size from the opened aperture condition ofFIGS. 1-4to the closed aperture condition ofFIG. 5. To move the wedges22outward to increase the size of the crimp aperture, the motion is simply reversed and will not be described in detail. Once the wedges reach the smallest crimp diameter, continuing past this point will cause the wedges to move back to the opened aperture condition. Minor adjustments, hence, would allow operation of this device in either direction (i.e., clockwise or counter-clockwise.

In another embodiment of the present invention, it is further contemplated that the crimping system may additionally include a chiller unit (not shown) wherein the chiller unit is configured to chill or cool the chamber of the iris30. This is advantageous when stents that must be cooled or chilled in order to reduce their diameters. For example, Nitinol stents must be cooled in order to reduce the diameter of the stent from an expanded diameter to a delivery diameter. The chiller may be integrally formed with the crimping system or may be a separate component that may be designed to work in conjunction with the apparatus.

Further still, it is contemplated that the end plates, drive plates or blades may be modified in order to function correctly with the chiller unit. The crimp aperture21itself, formed by the blades, is a highly insulated chamber, and is suitable for cryogenic processing. By providing an end cap77or the like, as illustrated inFIG. 10, the distal end of the crimp aperture21can be sufficiently sealed. As shown, the end cap77is formed for insertion into the receiving port45of the distal stationary end wall35″. A hub portion of the end cap is sized for a friction fit into the receiving port45, and an O-ring78forms a fluid tight seal. A set of access ports80,81extend through the end cap77that provide access to the crimp aperture21for selective cooling thereof.

Another embodiment includes cooling of the wedges themselves through cooling channels or passages. In this configuration, the blades could include communication orifices or the like that communicate a coolant from the coolant channels with the crimp aperture for cooling thereof.

Referring now toFIGS. 12-14, another aspect of the present invention is shown in which a stent crimping system, generally designated100, includes a chassis or base member101, a crimping assembly102, a clamping assembly103and a control unit105. The base member101is configured to retain the crimping assembly102and the clamping assembly103in alignment with one another, wherein the assemblies are aligned along a longitudinal axis106. The base member further includes additional mechanical components (not shown) such as drive motors, load cells and other control mechanisms that are controlled by the control unit105, wherein the control unit is programmed with a machine readable language to operate the mechanical components. In use, the control unit105may be associated with the control unit of the crimping assembly, wherein the control unit105would be utilized to control the expansion and contraction of the iris as described above. The control unit105may be user programmed to control the diameter of the iris within specified limits defined by the user. In the instances where a cryogenic cooler is utilized with the crimping assembly102it may be desirable to include a feedback loop within the control unit105, wherein the feedback loop may be utilize to calibrate the diameter of the crimping assembly in combination with a quill of known diameter. In accordance with the present invention there is provided a method of calibrating a crimping assembly in accordance with the present invention wherein the method includes the steps of (1) controlling a crimping assembly with a control unit, (2) calibrating the control unit with a quill of known diameter, (3) loading an endoprosthesis within an iris of the crimping assembly, (4) reducing the diameter of the iris to crimp the endoprosthesis, (5) loading the endoprosthesis into or onto a delivery system, and (6) calibrating the control unit. It is desirable to calibrate the control unit of the crimping assembly if a cryogenic cooler is being utilized during the crimping process due to tolerance changes of the iris as a result of contraction or expansion of the crimping assembly. By calibrating the diameter of the iris prior to crimping of the endoprosthesis a more consistent crimp diameter is achieved which is an improvement over conventional crimping techniques. It shall be understood that the process described above should be considered exemplary and not limiting in any manner. It is contemplated that the process may be modified, such as reducing or increasing the number of calibration cycles, utilizing a cooler before/during/or after the crimping process or other similar changes without departing from the scope of the invention.

The crimping assembly102, as shown inFIG. 13, includes a plurality of wedges or blades107arranged in a wedge assembly108that forms an iris110. At the center of the iris110is a crimp aperture111that is collectively formed by the distal end112of the blades107. The crimping assembly102further includes a housing113having opposed end plates115′ and115″, opposed drive plates116′ and116″, a rotation arm117, and rotator links118′ and118″. Disposed within the housing113is the wedge assembly containing the plurality of blades107. Each blade107is associated with the opposed end plates115′,115″ and the drive plates116′,116″ of the housing.

These blades107of the wedge assembly108are configured to translate, whereby the diameter of the cylindrical crimp aperture111changes relative to the translation of the plurality of blades107. The translation of the blades107may be performed manually by a user of the apparatus or, in a preferred embodiment, the crimping assembly102may be controlled by a control unit105. The control unit, for instance, is provided by a computer or the like, wherein the computer includes a program designed to control the translation of the plurality of blades.

FIG. 14best illustrates that blade107includes a proximal end120and the distal end112, wherein a first side121and an opposed second side122adjacent to the distal end converge to form a tip123. This tip123may be a sharp edge or may be slightly rounded or beveled as mentioned above. Each blade107may be constructed of a material or a combination of materials such as nylon, delrin, steel, aluminum, titanium, TEFLON®, plastics, composite materials, and other suitable materials. It is further contemplated that the blade107may be constructed of multiple pieces that may be assembled to form a unitary member, or alternatively blade107may be constructed as a unitary member.

It is further contemplated that blade107may further include a coating disposed thereon. For example, blade107may be coated with a coating that is configured to reduce friction, increase hardness, or alter other mechanical properties of the device according to the present invention. To reduce friction between adjacent blades or to reduce friction between the distal end portion of the blade and stent to be crimped, it is contemplated that the blade may be polished to a high degree in addition to or instead of coating the blade. For example, if it is desirable to form a blade of stainless steel, the blade may be constructed having a highly polished surface finish to reduce friction and to further reduce the possibility of scratching or otherwise damaging a stent to be crimped.

The blade107further includes a pair of opposed pivot pins125′,125″ disposed on each end section of the blade, wherein the pivot pins are aligned along an axis extending through a centerline plane of the blade and tip123. In addition to the pivot pins125′,125″, the blade107further includes a pair of opposed sliding mechanisms126′,126″ disposed proximal to the respective pins125′,125″ and adjacent the proximal end120of the blade.

These sliding mechanisms126′,126″ comprises first members127′,127″ and second members128′,128″, wherein the respective first members127′,127″ are fixedly attached to the opposed ends of the blade107and the respective second members128′,128″ are slideably received by the corresponding first member127′,127″. As will be described in greater detail below with reference to additional drawing figures, the respective second members128′,128″ are configured to be fixedly attached to a corresponding end plate115′,115″ of the crimping assembly100.

Referring now toFIGS. 15 and 16there is shown the end plates115′,115″ in accordance with the present invention, only end plate115′ of which will be described in detail. As shown, end plate115′ includes an aperture130′ extending therethrough from an outer surface to an inner surface. A recessed portion131′ surrounds the aperture130′, which in turn the respective second members128′ of the sliding mechanism126′ are fixedly supported. Each second member128′ of the sliding mechanism is fixedly attached to the end plate through suitable means, such as a fastener, welding or an appropriate adhesive. As shown, the inner surface132′ defines the recessed portion131, sized of a depth similar to that of the depth of second member128′. Hence, when the blades are slideably mounted to the opposed end plates115′,115″, the tolerance between the opposed ends of the blades107and that of the inner surfaces of the end plates115′,115″ is relatively small.

Briefly,FIGS. 13,17A and17B illustrate that a respective drive plate116′,116″ is rotatably disposed into the respective aperture133′,133″ from the outer side of the respective end plate115′,115″. Only one drive plate116′ will be described in detail in which the aperture133′ is defined extending therethrough from first side135′ to a second side136′. The second side136′ of the drive plate116′ further includes a hub portion137′ protruding from the surface thereof. The hub portion137′ is configured to be received within the aperture130′ of the corresponding end plate115′. The hub portion137′ further includes a plurality of radially extending slots138′ that are disposed about the circumference of the hub. The slots138′ are configured to slideably receive the pivot pin125′ of the blades107.

The end plates and the drive plates, as well as nearly all the components of the embodiments disclosed, may be constructed of materials such as metal, plastics or composites. In a preferred embodiment the end plates and the drive plates are constructed of rigid materials such as metal, such as steel or aluminum. The drive plates may be coated with a material to reduce friction between the drive plate and the end plate where the drive plate rotates within the aperture formed in the end plate.

Referring back toFIG. 13, there is shown an exemplary embodiment of the crimping assembly102in a partially exploded top perspective view. As illustrated, the crimping assembly102includes a housing113having two end plates115′,115″ coupled together by a two or more cross-beam140. It will be appreciated, of course, that the blades107of the crimping assembly102could be enclosed entirely by enclosure structure as well, similar to the embodiment ofFIGS. 1-11above.

The crimping assembly further includes the two drive plates116′,116″ and an actuation device141comprising the laterally extending rotation arm117flanked by a pair of opposed rotator link118′,118″ fixedly mounted to the corresponding drive plates116′,116″. Disposed within the housing113is the wedge assembly108comprising the plurality of blades107such as those described in detail above. As assembled, each blade107is associated with each end plate115′,115″ at opposed sides thereof through the sliding mechanism126′,126″ and with each drive plate through the pivot pin125′,125″, for movement of the iris110from the first diameter to the reduced second diameter.

In accordance with the present invention, the crimping system shown and described herein may be utilized to reduce the diameter of a medical device (not shown) such as a stent from a first diameter to a second diameter. The stent may be comprised of either balloon expandable stents or self-expanding stents. The plurality of blades of the crimping assembly102are configured to be movable, wherein the distal portions of the blades and the blade tips form an iris110having the crimp aperture111. The aperture may be moved between a first diameter and a second diameter, wherein the first diameter is of sufficient size to receive an expanded or un-crimped stent. After placing the sent within the crimp aperture111of the iris110, a force is applied to either the rotation arm117or rotator links118′,118″, thereby rotating the drive plate116′,116″. During rotation of the drive plates116′,116″ about the rotational axis142, the interior walls defining the radial slots138′,138″ of the second side136′,136″, cause the blade tips123to pivot about the pivot pins125′,125″, while linearly translating in the direction of the respective slider mechanism126′,126″. This combination of motion causes closure of the blade tips123(and hence the crimp aperture111of the iris110) from the first diameter to the second diameter. Accordingly, the rotation of the drive plates are translated to the plurality of blades which are in communication with the drive plates, via the opposed slider mechanism126′,126″ and pivot pins125′,125″.

The rotation arm or rotator links can be rotated manually by a user or automatically through the control system of the present invention. If the stent is a balloon expandable stent, prior to applying a force to the blades, a delivery system such as a balloon catheter is disposed within the crimp aperture, whereby as the aperture is drawn closed the stent is crimped about the balloon of the delivery device.

In another aspect of the present invention, the clamping assembly103is shown and described in detail in reference toFIGS. 18-21. This clamping assembly103is particularly suitable for securing a medical device, such as a delivery catheter for pre-operative preparation applications. For example, as shown in the schematic diagram ofFIG. 12, a delivery catheter (not shown) may be secured by the clamp assembly103while it's delivery portion is aligned along the longitudinal axis106and disposed in the crimper assembly102so that a crimp procedure can be performed.

Briefly, the clamping assembly103includes a lower clamp device145, an upper clamp device146, two opposed pivot levers147′,147″, a catheter retaining assembly148, and a clamp actuation mechanism150. As will be detailed below, these components cooperate to move the retaining assembly148between an opened condition (FIGS. 19,21,24and26), enabling insertion and positioning of the delivery device therein, and a closed condition (FIGS. 20,22,25and27), clamping the delivery device in place.

The lower clamp device145includes an elongated base153with a support plate151extending distally therefrom. The base153and the support plate151define a half-round or semi-circular-shaped seating groove152extending along an upper edge thereof (FIGS. 18,20and26). This groove152is configured to receive a specific sized delivery device. In the event that other delivery devices are to be utilized with the clamp assembly103, the groove152should be sized accordingly. It will be appreciated that the groove152need not be perfectly semi-circular. For example, it may be semi-polygonal shaped as well. The diameter or width of the groove152, however, should be at least the same as the outer diameter of the delivery device.

The elongated support plate151includes an elongated slot156that is oriented vertically. As will be described below, this elongated slot accommodates a securing pin171that mounts the pivot levers147′,147″ to the retaining assembly148, during movement of between the opened condition and the closed condition. The lower clamp further includes a pair of opposed pivot pins157extending outwardly in a direction substantially perpendicular to the elongated support plate.

The upper clamp device146is utilized to mount the clamp assembly103to the base101, and in alignment with the crimping assembly102(FIG. 12). It shall be understood, however, that the upper clamp device146may not be required in order for the clamp assembly to function as desired. As best shown inFIGS. 20 and 23, the upper clamp device146also includes an elongated base having a rectangular-shaped channel158extending along a lower edge portion thereof. The upper clamp device channel158is significantly wider than the seating groove152of the lower clamp device145. When the upper clamp device146is mounted to the lower clamp device145, a collective receiving channel is formed (FIGS. 24 and 25) that can accommodate the entire transverse cross-sectional dimension of the delivery device therethrough.

The catheter retaining assembly148includes an elongated U-shaped elastomeric member160, a pair of spaced-apart inner plates161′,161″ and a pair of spaced-apart outer plates162′,162″. The U-shaped elastomeric member is inverted such that an elongated contacting groove163thereof faces downwardly, in opposed relation to the elongated seating groove152of the lower clamp device support plate151. Each downwardly depending side wall of the elastomeric member160is straddled by a respective inner plate161′,161″ and a respective outer plate162′,162″. These plates are secured together with the appropriate fasteners (e.g., screws, bolts, rivets or similar attachment devices and methods), and provide structural support to the elastomeric member160.

When the retaining assembly148is moved to the closed condition (FIGS. 20,22,25and27), the elongated contacting groove163thereof contacts an upper side of the delivery device, and urges it securely against seating groove152of the support plate151. Hence, the elastomeric member160is preferably composed of an elastic material that provides sufficient elasticity to secure the delivery device without threatening the integrity of the delivery device components or materials. By way of example, the elastomeric member160may be compose of silicon rubber, rubber, latex, PVC or similar materials.

The two inner plates152include a downwardly depending vertical wing portion165′,165″, each of which is employed to cooperate with the pivot levers147′,147″ for movement thereof between the opened and closed conditions. As best illustrated inFIGS. 19,20,24and25, the pivot levers147′,147″ include pivot apertures166′,166″ formed to receive the pivot pins157of the lower clamp device. A proximal end of the pivot levers147′,147″ includes a contact block167disposed between the two levers for structural integrity thereof. At a distal end of each pivot lever147′,147″ is a pin receiving slot168′,168″, each of which is configured for co-axial alignment with a pin receiving port170′,170″ in the inner plate wing portions165′,165″. When the pin receiving slot168′,168″ and170′,170″ are co-axially aligned with the vertical slot156of the elongated support plate151, a securing pin171is passed therethrough to mount these components together. Accordingly, as the pivot levers147′,147″ are caused to rotate about a rotational axis174(FIGS. 26 and 27) of the pivot pins157, the retaining assembly, via the distal end of the pivot levers147′,147″ and the securing pin171, is caused to move between the opened condition (FIGS. 19,21,24and26) and the closed condition (FIGS. 20,22,25and27).

The lever pin receive slot168′,168″ are horizontally or laterally elongated while the support plate elongated slot156is vertically elongated. In either case, these slots are configured to accommodate the travel of the securing pin171during reciprocal movement of the retaining assembly between the opened condition and the closed condition.

Briefly, the movement of the pivot levers147′,147″ is controlled through the clamp actuation mechanism150that is configured to contact the contact block167at the proximal end thereof. As best illustrated inFIGS. 23-25, the actuation mechanism150includes a clamp bracket172and a support base173that is configured to mount the clamp bracket to the lower clamp device145. The clamp bracket172includes a bracket base175, a lever member176, a contact lever177and a four-bar linkage assembly178that cooperates to move the contact lever177between a first position (FIG. 24) and a second position (FIG. 25). In the second position, contact lever177contacts the contact block167, and rotates the pivot levers about the pivot pin rotational axis174.

The contact lever177can include a threaded contact screw180or the like that can be adjusted to adjust the contact against the contact block. While this one clamp actuation mechanism embodiment is shown and described, it will be appreciated that other conventional mechanism can be employed as well.

In operation, when the clamping assembly103is in the opened condition (FIGS. 19,21,24and26), the lever member176of the clamp actuation mechanism150is manually operated to move the contact lever177from the first position (FIG. 24) to the second position (FIG. 25), via the linkage assembly178. In the second condition, the contact lever177moves the contact screw180against the contact block167with a force sufficient to urge the proximal end of the pivot levers147′,147″ about the pivot pins157. As the pivot lever147′,147″ rotates about the rotational axis174of the pivot pins157, the distal end of the levers urge the catheter retaining assembly148, via the securing pin171, toward the closed position (FIGS. 20,22,25and27). Accordingly, the downward force of the elastomeric member160of the catheter retaining assembly thereby retains the catheter or delivery device between the retaining assembly and the seating groove152at the support plate151.

In addition to that described above, an important functionality of this clamp assembly is its ability to hold and retain a stent delivery device with sufficient force to prevent the device from moving relative to the clamp but with not too large a force where the delivery device is damaged. The force applied to the delivery device may be adjusted by adjusting the properties of the elastomeric material or by adjusting the clamping force applied to the elastomeric material by the clamping assembly.

As set forth above with crimping assembly ofFIGS. 1-11, it is further contemplated that the crimping system100in accordance with the present invention may additionally include a chiller unit (not shown) wherein the chiller unit is configured to chill or cool the crimping assembly102such that the crimping assembly102may then be utilized with stents that must be cooled or chilled in order to reduce their diameters. For example, Nitinol stents must be cooled in order to reduce the diameter of the stent from an expanded diameter to a delivery diameter. The chiller may be integrally formed with the crimping system100or may be a separate component that may be designed to work in conjunction with the apparatus. Further still, it is contemplated that the end plates, drive plates or blades may be modified in order to function correctly with the chiller unit.

If the stent to be crimped is a self-expanding stent, prior to applying a force to the blades, a delivery device is disposed within the clamp assembly. Once the stent has been crimped to a desirable delivery diameter, the clamp assembly is advanced toward the crimping assembly, or alternatively, the crimping assembly is advanced toward the clamp assembly, wherein the crimped stent is then disposed within the delivery device and the opening is enlarged by either removing the applied force or applying a force opposite of that previously applied.