Patent Description:
A stent is a generally cylindrical prosthesis introduced into a lumen of a body vessel via a catheterization technique. Stents may be self-expanding or balloon expandable. Balloon-expandable stents are typically crimped from an initial large diameter to a smaller diameter prior to advancement to a treatment site in the body. Before crimping, a balloon expandable stent is typically placed over an expandable balloon on a catheter shaft. In cases where the stent was manufactured in its fully crimped diameter, the stent is expanded and then crimped on the balloon. To ensure safety, the crimping process should be performed in a sterile environment. Over the years, attempts have been made to crimp the stent on a balloon during the operation in the sterile field. However, most stents are now "pre-crimped" on a suitable balloon in the factory and then delivered to the physician ready for use.

One example of a crimping device for stents based on movable jaws is disclosed in <CIT>. This crimping device uses sloped planes which force jaws to move from an open position to a closed position. One primary shortcoming is that the length of the sloped plane is given by a whole circle (<NUM>°) divided by the number of activated jaws. A long-sloped plane is preferable to reduce circumferential resistance or friction forces, but in order to achieve a smooth aperture for crimping the stent a large number of jaws is needed, which means a shorter sloped plane, less leverage and higher frictional forces. Therefore, the effectiveness of this type of device is substantially limited and may only be practical for stents which have a diameter of <NUM> to <NUM> in their expanded size.

In recent years, a variety of prosthetic valves have been developed wherein a valve structure is mounted on a stent and then delivered to a treatment site via a percutaneous catheterization technique. Prosthetic valves are typically much larger in diameter relative to coronary stents. While a typical expanded coronary stent diameter is only <NUM> to <NUM>, a stented prosthetic valve diameter will typically be in the range of about <NUM> to <NUM>, at least <NUM> times larger.

In another difference, coronary stents are stand-alone metallic devices which may be crimped over a balloon prior to packaging. For prosthetic valves, the stent functions as a scaffold to hold a valve structure which is typically made of biological materials such as pericardium valves or harvested valves. For improved function after deployment, it is often desirable to package such valves in the open (i.e., expanded) state in a preserving solution. Consequently, it is necessary to crimp the valve in the operation room a few minutes before implantation, therefore precluding pre-crimping by the manufacturer over a balloon.

Due to the unique crimping requirements for stent-based prosthetic valves, it has been found that existing crimping devices configured for use with coronary stents are not suitable for use stent-based prosthetic valves. In addition, as discussed above, existing crimping mechanisms suffer from a variety of shortcomings which limit their ability to be adapted for use with stent-based prosthetic valves. Due to the deficiencies associated with existing crimping technology, a new crimping device was described in co-owned <CIT> and relates to a crimping device that is adapted to crimp a prosthetic valve as part of the implantation procedure.

Another version of a prosthetic heart valve crimper is marketed by Machine Solutions Inc. of Flagstaff, Arizona. The HV200 is a disposable crimper that uses multiple pivoting segments to crimp percutaneous heart valves. The Machine Solutions crimpers are also disclosed in <CIT> and <CIT>. These crimping devices are based on segments which rotate about pivot pins to create radial compression. Unfortunately, the pivoting design tends to concentrate stress in certain areas of the individual segments, and in the mechanism for pivoting them. Also, the user must apply significant force to close the crimper aperture around a relatively large percutaneous heart valve.

<CIT> discloses a crimping mechanism for prosthetic heart valves having linearly moving jaws which has the capacity to crimp a relatively large size valve down to a small delivery size, but is also relatively large in size.

Although the heart valve crimping technology available to date provides an improvement over the existing stent crimper technology, it has been found that a need still exists for a more effective device. It is desirable that such a device be capable of crimping a valve from a diameter of about <NUM> to a crimped size of about <NUM> without requiring excessive force and without inducing high mechanical stresses within the device. It is also desirable that such a device is simple to use and relatively inexpensive to manufacture. It is also desirable that such a device be sterile and suitable for manual operation in a catheter lab or operating room. The present invention addresses this need.

The present invention relates to a crimping device for crimping expandable prosthetic heart valves having support frames or stents as defined in claim <NUM>. Embodiments of the invention are recited in the dependent claims.

The crimping mechanism includes a plurality of jaws configured for coordinated inward movement toward a crimping axis to reduce the size of a crimping iris around a stented valve. A rotating cam wheel acts on the jaws and displaces them inward. A number of Cartesian guide elements cooperate with the jaws to distribute forces within the crimping mechanism. The guide elements are located between the crimping jaws and an outer housing and are constrained by the outer housing for movement along lines that are tangential to a circle centered on the crimping axis. The guide elements engage at least some of the crimping jaws while the rest are in meshing engagement so as to move in synch. An actuation mechanism includes a lead screw, carriage assembly and a linkage to rotate the cam wheel with significant torque.

In one embodiment, a prosthetic valve crimping device capable of reducing the diameter of an expandable prosthetic stented valve comprises a plurality of crimping jaws in meshing engagement and circumferentially arranged around a crimping orifice having a central crimping axis, each having inner crimping wedges. A rotating cam wheel acts on the crimping jaws and displaces them generally radially inward, while a stationary outer housing contains the cam wheel and crimping jaws. Finally, a plurality of guide elements are each constrained by fixed grooves in the outer housing for movement between first and second positions along lines that are tangential to a circle around the central axis, wherein the guide elements move at least some of the crimping jaws along the lines such that all of the crimping wedges of the crimping jaws translate inward along radial lines toward the crimping axis.

In one aspect, the crimping wedges are made of a different material than the rest of the crimping jaws. The guide elements may be separate elements from the crimping jaws. Preferably, the guide elements are rigidly coupled to the at least some of the crimping jaws by being integrally formed therewith or fastened thereto.

Advantageously, the crimping jaws each comprise an assembly of a pair of traveling blocks flanking the cam wheel and one of the crimping wedges that extends across a central orifice in the cam wheel. The cam wheel may include two disks having spiral cam slots that act on cams secured to each of the flanking traveling and that extend axially inward into the cam slots. Also, the cam wheel disks may each have a cam lever projecting radially outward therefrom that is driven by a carriage assembly on a lead screw. Preferably, a linkage between the cam levers and the carriage assembly increases a torque applied to the cam wheel when the carriage assembly reaches opposite ends of the lead screw.

In a second aspect, the present application discloses a prosthetic valve crimping device capable of reducing the diameter of an expandable prosthetic stented valve. The device has a plurality of crimping jaws in meshing engagement and circumferentially arranged around a crimping orifice having a central crimping axis, wherein the crimping jaws each comprise an assembly of a pair of spaced apart traveling blocks and a radially inner crimping wedge that extends therebetween. A rotating cam wheel acts on the crimping jaws and displaces them generally radially inward, the cam wheel including two disks having spiral cam slots that act on cams secured to each of the flanking traveling blocks and that extend axially inward into the cam slots. A stationary outer housing contains the cam wheel and crimping jaws, and a lower actuation mechanism including a lead screw and carriage assembly is coupled to rotate the cam wheel. The pair of traveling blocks of at least some of the crimping jaws are constrained by fixed grooves in the outer housing for movement along lines that are tangential to a circle around the central axis such that all of the crimping wedges of the crimping jaws translate inward along radial lines toward the crimping axis.

In the device of the second aspect, the cam wheel disks each may have a cam lever projecting radially outward therefrom that is driven by the carriage assembly on the lead screw via a linkage between the cam levers and the carriage assembly that increases a torque applied to the cam wheel when the carriage assembly reaches opposite ends of the lead screw. Further, a drive motor may be provided to actuate the lead screw. Also, the crimping wedges may be made of a different material than the rest of the crimping jaws.

The device of the second aspect may further include a plurality of guide elements which are each constrained by fixed grooves in the outer housing for movement between first and second positions along lines that are tangential to a circle around the central axis, the guide elements moving at least some of the crimping jaws along the lines such that all of the crimping wedges of the crimping jaws translate inward along radial lines toward the crimping axis.

In one embodiment, there are half the number of guide elements as crimping jaws, such that some of the crimping jaws are driven and some are followers. Preferably, the guide elements are rigidly connected to the traveling blocks of half of the crimping jaws by being integrally formed therewith or fastened thereto.

In either aspect, each of the guide elements may comprise a rectilinear plate in an irregular diamond shape with four vertices and straight sides therebetween with an indentation on one side adjacent one of the vertices, and when the guide elements are displaced to the second positions along the lines, one of the vertices of each fits closely within the indentation on the adjacent guide member, and the nested contact between all of the guide elements in this manner provides a positive stop on further inward movement of the crimping mechanism.

The present invention provides an improved crimper for stents or prosthetic valves. The particularly advantageous features of the present crimper enable reduction in diameter of relatively large stents or prosthetic valves in conjunction with a small sized crimper that generates high crimping forces to result in small final diameters. The crimper is especially suited for crimping prosthetic heart valves which have expanded diameters significantly larger than most stents currently in use. According to Chessa, et al. , the Palmaz-Genesis XD stents (Cordis J&J Interventional Systems Co. ) are designed for an expansion range of <NUM>-<NUM>, and are considered as either large or extra-large stents (see, <NPL>). The most frequently used stents are significantly smaller, in the <NUM>-<NUM> range. Crimpers for these stents have proved inadequate for reducing in size even larger prosthetic valves, such as the stented prosthetic heart valves. Conversely, aspects of the present crimper may be applicable for use in crimping stents as well, although certain features described herein make it particularly well-suited for crimping large diameter stents, stent grafts, and prosthetic valves.

The term "stented valve" as used herein refers to prosthetic valves for implant, primarily prosthetic heart valves but also conceivably venous valves and the like. A stented valve has a support frame or stent that provides primary structural support in its expanded state. Such support frames are typically tubular when expanded, and may be expanded using a balloon or due to their own inherent elasticity (i.e., self-expanding) or by mechanical means. An exemplary stented valve is illustrated with respect to <FIG>, although the present invention may be useful for crimping other such prosthetic valves.

<FIG> illustrates an exemplary balloon-expandable prosthetic heart valve <NUM> having an inflow end <NUM> and an outflow end <NUM>. The valve includes an outer stent or support frame <NUM> supporting a plurality of flexible leaflets <NUM> within. <FIG> shows the valve <NUM> in its expanded or operational shape, wherein the support frame <NUM> generally defines a tube having a diameter Dmax, and there are three leaflets <NUM> attached thereto extending into the cylindrical space defined within to coapt against one another. In the exemplary valve <NUM>, three separate leaflets <NUM> are each secured to the support frame <NUM> and to the other two leaflets along their lines of juxtaposition, or commissures. Of course, a whole bioprosthetic valve such as a porcine valve could also be used. In this sense, "leaflets" means separate leaflets or the leaflets within a whole xenograft valve.

<FIG> shows the valve <NUM> mounted on a balloon <NUM> prior to inflation. The crimped outer diameter of the valve <NUM> is indicated at Dmin. The balloon <NUM> typically mounts on the end of a catheter <NUM> which is guided to the implant sites over a steerable wire <NUM>.

Further details on the exemplary prosthetic heart valves of a similar type can be found in <CIT> and <CIT>. In addition, the Sapien® line of heart valves available from Edwards Lifesciences of Irvine, CA are balloon-expandable prosthetic heart valves of a similar nature.

<CIT> discloses a crimping mechanism for prosthetic heart valves which has the capacity to crimp a relatively large size valve down to a small delivery size. However, the mechanism in the '<NUM> patent is relatively large due to the need to create high leverage forces to crimp the large diameter valves. In contrast, the crimper mechanisms disclosed herein create radial jaw motion using Cartesian movement guiding elements, close to the central aperture. Consequently, the size of the crimping jaws is reduced dramatically and the stiffness (or the ability to withstand higher crimping forces) of the jaws is increased.

The crimper mechanisms of the present application efficiently reduce the size of prosthetic valves from up to <NUM> (Dmax) down to <NUM> (Dmin). Prosthetic heart valve sizes are typically anywhere between <NUM> up to about <NUM>. The minimum reduction in size is thus around <NUM> and the maximum around <NUM>. In contrast, typical coronary stents have an expanded diameter of between about <NUM>-<NUM> and are crimped down to a minimum diameter of between about <NUM>-<NUM>, for a total maximum size reduction of around <NUM>. To distinguish conventional stent crimpers, the present invention provides a diameter reduction of at least <NUM>, and preferably at least <NUM>. Because diametrically opposed jaws act toward each other to reduce the size of the prosthetic valves, each crimp the valve half the distance of the entire reduction in diameter. This means each jaw moves radially inward at least <NUM>, and more preferably at least <NUM>.

With reference now to <FIG>, one preferred embodiment of an improved prosthetic heart valve crimping mechanism <NUM> is shown. The crimping mechanism <NUM> includes an outer housing <NUM> enclosing a plurality of crimping jaws <NUM> arranged about a central crimping axis <NUM>. As will be described, there are preferably <NUM> crimping jaws <NUM>, although other numbers of jaws are possible. The jaws <NUM> are initially shown retracted outward in <FIG> so as not to be visible within a receiving orifice <NUM> sized large enough to receive an expanded heart valve <NUM> such as shown in <FIG> illustrates the crimping jaws <NUM> displaced radially inward in a coordinated manner to form a crimping iris <NUM> defined by the combined inner surfaces of the assembly of jaws. The crimping iris <NUM> has a minimum diameter small enough to completely crimp the heart valve <NUM> onto the balloon <NUM>. Although not shown, the crimping operation involves placing the expanded heart valve <NUM> around the balloon <NUM> before inserting the assembly into the orifice <NUM> and actuating the crimping jaws <NUM>.

A lower portion of the outer housing <NUM> is cut away in both <FIG> to expose a portion of an actuating mechanism therein. In particular, a relatively large diameter horizontally oriented lead screw <NUM> is journaled for rotation on either side of the housing <NUM> and perpendicular to the crimping axis <NUM>. Although not shown, a motor in the lower part of the housing <NUM> is desirably connected via a power transmission to drive the lead screw <NUM> and increase applied forces. Alternatively, one or both ends of the lead screw <NUM> projects outward from the housing <NUM> and terminates in a nut or other such keyed element. By inserting a crank or key into one of the ends of the lead screw <NUM>, it may be manually rotated about its axis. An internally threaded carriage <NUM> travels back and forth along the lead screw <NUM> when it rotates. The carriage <NUM> features a shaft stub <NUM> projecting from one side that is retained within a large slot <NUM> formed in a lever arm <NUM> of a cam wheel <NUM> (see <FIG> and <FIG>), thus preventing rotation of the carriage with the lead screw.

Further details of the interaction between the cam wheel <NUM> and crimping jaws <NUM> will be explained more fully below. However, as seen in <FIG>, rotation of the lead screw <NUM> causes the carriage <NUM> to travel from right to left which in turn interacts with the lever arm slot <NUM> and rotates the cam wheel <NUM> clockwise (CW). Rotation of the cam wheel <NUM> in this manner causes the jaws <NUM> to be displaced from their radially outward to their radially inward positions, thus crimping the heart valve <NUM>.

<FIG> is an exploded perspective view showing the inner components of the exemplary crimping mechanism <NUM>. The outer housing <NUM> includes two molded halves that together provide the bearing mounts for the lead screw <NUM>. Although an inside face of only one of the housing halves is shown, both include a plurality of linear guide channels <NUM> molded into their inner faces and disposed in a spoke-like manner tangentially around the receiving orifices <NUM>. The outer housing <NUM> halves sandwich therebetween a crimping jaw assembly <NUM>.

<FIG> is a partially exploded perspective view of the crimping mechanism <NUM> showing the crimping jaw assembly <NUM> and one of the halves of the outer housing <NUM> with its guide channels <NUM>. The crimping jaw assembly <NUM> has a generally cylindrical profile that fits closely within a similarly-shaped upper portion of the outer housing <NUM>, and is centered along the crimping axis <NUM>. The crimping jaw assembly <NUM> is made up of the moving parts within the crimping mechanism <NUM>, aside from the lead screw <NUM> and carriage <NUM>. With reference also to <FIG>, the crimping jaw assembly <NUM> comprises an axial sandwich of elements in the middle of which is the cam wheel <NUM>. The crimping jaws <NUM> flank the cam wheel <NUM>, and a number of Cartesian guide elements <NUM> are arranged on the outside of the crimping jaws <NUM>. In turn, the crimping jaw assembly <NUM> is firmly located within the two halves of the housing <NUM>, but may rotate therein.

To understand the interaction between the moving parts of the crimping jaw assembly <NUM>, it is necessary to start from the cam wheel <NUM> and move axially outward. The cam wheel <NUM> is rotated by the lead screw <NUM> and carriage <NUM>, and thus forms the prime mover of the crimping jaw assembly <NUM>. In general, rotation of the cam wheel <NUM> initiates movement of all the other pieces, although as will be described below physical interaction and guiding contact between the pieces creates additional reaction forces that distribute the forces from the cam wheel.

<FIG> is a perspective view of the exemplary cam wheel <NUM>, which includes a pair of parallel annular discs <NUM> joined on their inner circular edges by an annular hub <NUM>. A plurality of axially-oriented rollers <NUM> are journaled for rotation between the two discs <NUM> and circumferentially distributed in an annular space <NUM> defined radially outside of the hub <NUM>. Each of the roller <NUM> projects slightly outward from the outer edges of the discs <NUM> so as to contact the outer housing <NUM> to facilitate rotation therein and provide stability to the crimping operation. As also seen in <FIG>, each of the annular discs <NUM> includes a series of arcuate cam slots <NUM> formed therein which curve generally from their radially inner to their radially outer edges. Each of the cam slots <NUM> is curved so as to be radially outwardly convex. The arcuate cam slots <NUM> on the two discs <NUM> are aligned and have the same shape such that looking at the outer face of one disc the cam slots <NUM> extend radially outward in a clockwise (CW) direction (i.e., <FIG>), while looking at the outer face of the other disc the slots extend radially outward in a counter-clockwise (CCW) direction.

In the illustrated embodiment, there are twelve cam slots <NUM> nested relatively closely to each other around each disc <NUM>. Each two aligned slots <NUM> in the two discs <NUM> act on one of the jaws <NUM>, and therefore in the preferred embodiment there are twelve jaws <NUM>. It should be understood that the number of crimping jaws <NUM>, and thus the number of cam slots <NUM>, may be modified but is preferably between <NUM>-<NUM>.

As seen in <FIG>, each of the crimping jaws <NUM> includes a radially inner crimping wedge <NUM> connecting a pair of axially spaced apart, generally triangular outer traveler blocks <NUM>. The elevational view of <FIG> shows that the traveler blocks <NUM> each span an included angle θ which varies depending on how many jaws <NUM> are utilized, and is preferably <NUM>° with twelve jaws. When the jaws <NUM> are assembled along with the cam wheel <NUM>, as seen in <FIG> with the jaws <NUM> in their radially outward positions, the crimping wedges <NUM> are positioned within a central aperture defined inside the annular hub <NUM> of the cam wheel <NUM>. The inner surfaces of the crimping wedges <NUM> define the aforementioned iris <NUM> of the crimping mechanism <NUM>. The traveler blocks <NUM> of each of the jaws <NUM> closely flank the annular discs <NUM> of the cam wheel <NUM>, and small cam followers <NUM> extending axially inward from each of the blocks insert into the arcuate cam slots <NUM>. Each of the cam followers <NUM> has a generally rounded configuration and is angled in a manner that aligns with a tangent to the curve of the arcuate cam slots <NUM>. The cam followers <NUM> are sized so as to be slightly smaller than the width of the cam slots <NUM>, and may be made of a lubricious material such as Nylon or Teflon to facilitate sliding therein. The cam followers <NUM> are located at a radially outer extent of each of the traveler blocks <NUM>.

At this stage, a further word about materials is relevant. Many of the components are molded of a suitable polymer, such as the outer housing <NUM> and cam wheel <NUM>. The lead screw <NUM>, carriage <NUM> and of course motor parts will preferably be metallic, though some may also be polymer. The crimping jaws <NUM> may be a molded polymer, though the inner crimping wedge <NUM> which contacts the article being crimped is desirably a material with high strength & stiffness along with low friction, such as reinforced Nylon. In this respect, the inner crimping wedges <NUM> may be inserts to the larger jaws <NUM>. Likewise, as mentioned, the cam followers <NUM> are preferably stiff and low friction, such as Nylon. Of course, alternatives exist and these are just exemplary materials.

It will thus be clear that rotation of the cam wheel <NUM> causes a radially inward motion of the crimping jaws <NUM> due to the interaction between the arcuate cam slots <NUM> and the cam followers <NUM>. <FIG> are elevational views of the inner crimping mechanism <NUM> showing the central cam wheel <NUM> and crimping jaws <NUM> assembled thereon in both open and closed crimping jaw positions. Only one of the arcuate cam slots <NUM> as well as the cooperative cam follower <NUM> on one of the jaws <NUM> is shown in phantom. It should be understood that although only one each is shown, there are two cam slots <NUM> and two cam followers <NUM> associated with each jaw <NUM>. The jaw <NUM> on which the cam follower <NUM> is shown is highlighted by extending dashed lines along respective angled edges to form angles α and β with the horizontal.

<FIG> show the lever arm <NUM> of the cam wheel <NUM> rotating in a clockwise (CW) direction such that the cam followers <NUM> on each jaw <NUM> are acted on by the arcuate cam slots <NUM>. Because the cam slots <NUM> curve radially inward as the wheel <NUM> rotates clockwise, a radially inward camming force is transmitted to the cam followers <NUM>. Because of the sliding interactions between the jaws <NUM>, inward movement of all of the jaws <NUM> from their rigid connection to their respective cam followers <NUM> is the same. It should be noted that the highlighted crimping jaw <NUM> remains in the same rotational orientation while it translates radially inward and downward. That is, the angles α and β that describe the orientation of the jaw <NUM> relative to horizontal remain the same. The same is true for all of the jaws <NUM>. As a result of this movement, the inner surfaces of the crimping wedges <NUM> define a radially constricting iris <NUM>. Additionally, although the absolute angle of a tangent line drawn with respect to the curvature of the arcuate slot <NUM> varies from one end of the slot to the other, the orientation of the cam follower <NUM> remains parallel to these tangent lines because of the movement of the respective jaw <NUM>. This facilitates sliding movement of the cam followers <NUM> within the slots <NUM>.

The crimping jaws <NUM> have cooperating sliding surfaces such that they all moved together with the same degree of translation as one another, albeit along different angles. In particular, each of the angular edges of the traveler blocks <NUM> cooperates with the adjacent traveler block edges in a tongue and groove fashion. With reference back to <FIG>, each of the traveler blocks <NUM> has a sliding rail <NUM> thereon that mates with an oppositely-oriented sliding rail on the traveler block <NUM> on the adjacent jaw <NUM>. This interaction can be seen in the perspective view of <FIG>. The sliding engagement of the rails <NUM> helps prevent binding between the jaws <NUM> as they move inward together.

Furthermore, the starting positions of the crimping jaws <NUM> and the angles of the edges of the traveler blocks <NUM> causes the assembly of jaws to rotate when they are cammed inward. In essence, each of the crimping jaws slides inward relative to one of its adjacent crimping jaws, and the resulting displaced shape seen in <FIG> somewhat resembles a pinwheel. The reader will also see from comparison of <FIG> where the highlighted crimping jaw <NUM> translates radially inward and downward, amounting to a clockwise rotation thereof.

As seen in <FIG>, the crimping jaws <NUM> also have linear guide slots <NUM> on the outer faces of both of the traveler blocks <NUM>. These guide slots <NUM> interact with the aforementioned Cartesian guide elements <NUM>, as will be explained below. With specific reference to <FIG>, the guide slot <NUM> of each jaw <NUM> bisects included jaw angle Θ.

<FIG> is an elevational view of an inner face of one half of the outer housing <NUM> showing the fixed guide channels <NUM>. As mentioned above, the guide channels <NUM> lie tangent to the central orifice <NUM> in the housing <NUM>. The guide channels <NUM> preferably comprise axial depressions in an outer plate <NUM> of the housing <NUM>, with the housing halves including the guide channels desirably being injection molded. Radially inner ends of each guide channel <NUM> merge with an adjacent guide channel at about a mid-point thereof. Because there are six guide channels <NUM> spaced equidistantly and oriented evenly around the orifice <NUM>, the inner portions of the guide channels define vertices of a hexagon closely surrounding the orifice. Each guide channel <NUM> extends from a vertex of the hexagon past its point of tangency with the orifice <NUM> and outward to an outer rim <NUM> of the housing <NUM>. The guide channels <NUM> interact with the Cartesian guide elements <NUM>, as will be explained below. The number of guide channels depends on the number of jaws; namely, half the of number of jaws.

<FIG> shows a plurality of the Cartesian guide elements <NUM> arranged in space in the same manner as they would be when interacting with the outer housing <NUM>, <FIG> shows an individual Cartesian guide element <NUM> in isolation, while <FIG> superimpose the guide elements onto the outer housing and channels <NUM>. Each of the guide elements <NUM> comprises an angular generally flat rectilinear plate <NUM> having a pair of raised linear bars 98a, 98b projecting from opposite inner and outer faces. The opposed linear bars 98a, 98b are oriented perpendicular to each other, and thus together define a right-angle cross, albeit on opposite faces of the guide elements <NUM>. Outer faces of the guide elements <NUM> abut the outer plate of the housing <NUM> such that the outer linear bars 98a on that side fit closely within the fixed guide channels <NUM>. On the inner face, the guide elements <NUM> contact the assembly of the crimping jaws <NUM>, and the inner linear bars 98b fit closely within the guide slots <NUM> on six of the guide elements. Because the outer linear bars 98a are constrained within the guide channel <NUM>, the guide elements <NUM> are also constrained to move linearly between first and second positions parallel to the guide channels.

<FIG> shows the locations of the guide elements <NUM> superimposed on the outer housing <NUM> when in radially outward positions (as also in <FIG>). As mentioned, the outer linear bars 98a extend within and are guided by the guide channels <NUM>. In this starting position, radially outer edges of the rectilinear plates <NUM> are close to the outer rim <NUM> of the housing <NUM>, and their radially inner edges are positioned just outside of the central orifice <NUM>. <FIG> is a similar view showing the guide elements <NUM> in radially inward positions. The outer linear bars 98a slide inward along the guide channels <NUM>, and the rectilinear plates <NUM> fit closely together. The rectilinear plates <NUM> define an irregular diamond shape with generally four vertices at the outer extents of the crossed linear bars 98a, 98b. Straight sides extend between the vertices, and there is an indentation <NUM> on one side adjacent one of the vertices. When the guide elements <NUM> are in their radially inner positions, one of the vertices of each fits closely within this indentation <NUM> on the next, and the nested contact between all of the guide elements <NUM> in this manner provides a positive stop on further inward movement of the crimping mechanism <NUM>.

<FIG> are elevational views similar to <FIG> with the crimping jaw assembly <NUM> in place but also showing the Cartesian guide members <NUM> interacting with the crimping jaws <NUM>. The guide members <NUM> are termed "Cartesian" because of the opposite crossed linear bars 98a, 98b on each. That is, as described above, the guide member <NUM> are constrained to move linearly along the guide channels <NUM> in the outer housing <NUM>. At the same time, interaction between the inner linear bars 98b on each member <NUM> and the guide slots <NUM> on every other crimping jaw <NUM> constrains those jaws to move in the direction of the associated guide member <NUM>.

Prior to discussion of this coordinated movement, it should be noted that there are only six guide members <NUM>, while there are twelve crimping jaws <NUM>. Therefore, as seen in <FIG>, each of the guide members <NUM> interacts with every other crimping jaw <NUM>. The six crimping jaws 44a that interact with the guide members <NUM> can be termed guided jaws, while the six crimping jaws 44b that do not interact with the guide members are termed follower jaws. However, it is important to remember that each of the crimping jaws <NUM> has cam followers <NUM> thereon, and thus each of the crimping jaws is driven directly by the cam wheel <NUM>.

With reference again to <FIG>, Cartesian axes <NUM>, <NUM> are superimposed over one combination of guide member <NUM> and its guided jaw 44a. A first axis <NUM> extends along the outer linear bar 98a on the guide member <NUM>. The reader will understand that the outer linear bar 98a interacts with the guide channels <NUM> on the half of the outer housing which is not shown. Therefore, the guide member <NUM> is constrained for linear movement along the first axis <NUM>. A second axis <NUM> extends along the inner linear bar 98b on the guide member <NUM>, which corresponds to the guide slot <NUM> on the guided jaw 44a. The second axis <NUM> translates with the guide member <NUM>, always remaining perpendicular to the first axis <NUM>. Both the guided jaw 44a and the guide member <NUM> move together. This arrangement reduces frictional losses and allows an option to combine the guided jaws <NUM> and the guide elements <NUM>.

Now with respect to <FIG>, the cam wheel <NUM> has rotated clockwise causing sliding movement of all of the crimping jaws <NUM>. As the guided jaw 44a begins to move inward, it is constrained to move along the first axis <NUM> with the corresponding guide member <NUM>. Likewise, all of the six guided jaws <NUM> are constrained to move with their corresponding guide members <NUM>. As each guided jaw 44a starts to move inward it slides relative to one of the two adjacent follower jaws 44b. Of course, each follower jaw 44b is acted on by two adjacent guided jaws 44a. Because of the angled sides of the adjacent jaws <NUM>, as explained above with respect to <FIG>, the assembly of jaws begins to rotate clockwise. The circumferential component of movement of each of the guided jaws <NUM> transfers forces via the guide slots <NUM> to the inner linear bars 98b on the guide members <NUM>. This starts the guide members <NUM> translating along the first axis <NUM>.

It should be mentioned that the provision of two sets of force actuators (disks <NUM>, traveler blocks <NUM>, and guide members <NUM>) results in a symmetric, balanced system and the stresses are reduced. Of course, a single disk <NUM> and associated crimping elements is possible, but would require a more robust structural design.

As the guide members <NUM> and the guided jaws 44a translate along the first axes <NUM>, they continue to move inward relative to the outer housing <NUM>. Of course, although they are not directly in contact with the guide member <NUM>, the follower jaws 44b move in a like manner because they are also acted on by the cam wheel <NUM>, and from the symmetry and mating edge contact between the jaws. <FIG> isolates a central one of the guided crimping jaws 44a from <FIG> and shows the jaw with its absolute movement <NUM> along the first axis <NUM>. Continued rotation of the cam wheel <NUM> eventually moves the crimping jaws <NUM> into the positions shown in <FIG> and <FIG>. It is also worth noting that the tip of the crimping wedge <NUM> on each jaw translates radially inward along a radial line <NUM> through the central crimping axis <NUM> (see <FIG>). That is, the composite movement <NUM> is parallel to the radial line <NUM> through the crimper axis <NUM>. This ensures even crimping of the stent or valve.

The relative movements of the cooperating elements in the crimping mechanism <NUM> will occur regardless if there is an object being crimped or not. However, when an object such as the expanded heart valve <NUM> of <FIG> is being crimped, it applies substantial resistance to the crimping mechanism <NUM>. More specifically, the hoop strength of the expanded heart valve <NUM> provides a radially outward reaction force <NUM> directly to the crimping wedges <NUM> of the jaws <NUM>, as indicated in <FIG>.

Without the guide members <NUM>, the mechanism is not balanced and the reaction force <NUM> will tend to rotate the jaws <NUM>. Further, without the guide members <NUM> this reaction force would be translated through the crimping jaws <NUM> to the cam followers <NUM>, and thus to the arcuate cam slots <NUM> of the cam wheel <NUM>. Although the cam slots <NUM> are relatively robust, the cam followers <NUM> are not only susceptible to deformation from stress, but also binding. However, because of the contact between the guide members <NUM>, crimping jaws <NUM> and fixed outer housing <NUM>, the reaction forces from the crimping process are transferred and distributed such that the stress on the cam followers <NUM> is reduced. In particular, the Cartesian guide members <NUM> absorb a considerable amount of the stress and provide an effective companion for the crimping jaws <NUM>. With respect to <FIG>, the radially outward reaction force <NUM> from the crimping process translates into a torque on the crimping jaw 44a. This torque is resisted primarily by the rigid constraint imposed on the guide member <NUM> by the outer housing guide channels <NUM> to move along the first axis <NUM>. To be more explicit, the clockwise torque on the guided jaw 44a would be translated directly to the corresponding guide member <NUM> because of the interaction between the guide slot <NUM> and the inner linear bar 98b, and the rotational torque within be resisted by the guide member <NUM> because it is fixed rotationally with respect to the outer housing <NUM>.

One benefit over previous crimpers is in the smaller mechanism size (~<NUM> the size of current crimpers) and in the ability to operate under high crimping forces (small and stiff crimping jaws). The jaws <NUM> are displaced essentially radially using the Cartesian guiding element <NUM> positioned close to the central orifice <NUM>. This guided concept enables dramatic reduction of the size of the crimping jaws <NUM> and the stiffness (or the ability to withstand higher crimping forces) of the jaws is increased. The radial alignment mechanism provided by the guiding elements <NUM> is based on steep angular movement translated to radial forces imposed close to the central crimping axis. The guiding elements <NUM> translate the angular movement from the cam wheel <NUM> to a radial force, by essentially separating it into a Cartesian movement. In this movement, the jaws <NUM> are moving radially similarly to the previous crimpers, and the guiding elements <NUM> move with them, in the tangential housing channels <NUM>.

In a preferred embodiment, the width of the crimping mechanism <NUM>, or approximately the diameter of the cam wheel <NUM>, is about <NUM>. A total height of the crimping mechanism <NUM>, such as shown in <FIG> which includes the cam wheel <NUM> above the lead screw <NUM> and associated actuators, is about <NUM>. Of course, those exemplary sizes are for a mechanism capable of crimping a balloon-expandable prosthetic heart valve <NUM> such as shown in <FIG> down to a delivery size shown in <FIG>. The mechanism must be robust enough to crimp a stainless steel support frame of the heart valve <NUM> from, for example, <NUM> (Dmax) down to <NUM> (Dmin). Less stiff frames or less of a size reduction may enable the crimper to be even further reduced in size and, conversely, a larger size reduction may require a larger crimper.

<FIG> are schematic perspective views of an alternative embodiment of a crimping mechanism <NUM> in both open and closed positions of crimping jaws <NUM>, respectively. The entire crimping mechanism <NUM> is not shown, but will be similar to that shown in <FIG>. The main difference in the crimping mechanism <NUM> is a modification to the guide members <NUM>. That is, rather than having a diamond-shape plate with opposing crossed linear bars, as before, the guide members <NUM> are simply perpendicular bars attached together. The inner bars will extend within guide slots <NUM> in the crimping jaws <NUM>, while the outer bars will slide within fixed guide channels in an outer housing (not shown). In all other respects, the crimping mechanism <NUM> works the same as was described above.

<FIG> and <FIG> illustrate a further crimping mechanism <NUM> similar to that shown in <FIG> but with fewer guide elements <NUM>. The guide elements <NUM> are simple crossed linear bars, as described above with respect to <FIG>. Further, there are still twelve crimping jaws <NUM>. In contrast to the earlier embodiments, however, there are only two guide elements <NUM>. Operation of the crimping mechanism <NUM> as seen in <FIG> is similar to that described above, where a lead screw <NUM> turns a cam wheel (not shown) which initiates the inward movement of the crimping jaws <NUM>. Because the crimping jaws <NUM> are all linked in a tongue and groove fashion as was described above, they would move in sync in and out even without guide elements <NUM>. The guide elements <NUM> only mesh with two of the crimping jaws <NUM>, but still provide a reduction in stress and distributed application of force. Two guide elements <NUM> is considered a minimum, and three, four, or six are contemplated for a twelve jaw mechanism. A practical maximum number of guide elements <NUM> is six in the illustrated embodiments, or half the number of jaws. This is so that the guide elements <NUM> do not interfere with each other as they slide back and forth.

<FIG> schematically depict a still further crimping mechanism <NUM> of the present application that utilizes a compressible sleeve, such as a soft elastomer, rather than a plurality of separate jaws. <FIG> are elevational views of the crimping mechanism <NUM> with a front cover removed to show internal components in the positions of <FIG>, respectively. The crimping mechanism <NUM> features a cam wheel <NUM> that rotates within a pair of end plates <NUM> (only one shown). The end plates <NUM> are fixed over a housing <NUM> within which is located an actuation mechanism, much like the lead screw assembly described above.

A compressible sleeve <NUM> is held rotationally still between the end plates <NUM> and comprises an annular elastomeric sleeve with outer axial grooves. An inner lumen or orifice <NUM> defined by the sleeve <NUM> constricts upon rotation of the cam wheel <NUM> to a smaller size orifice <NUM>', as seen in <FIG>.

With reference to <FIG>, as well as to <FIG>, a plurality of linkage plates <NUM> are arranged for coordinated movement within the cam wheel <NUM>. More particularly, outer ends <NUM> of the plates <NUM> are journaled for rotation in corresponding bores <NUM> around the outer perimeter of the cam wheel <NUM>. The cam wheel <NUM> may have a short segment of gear teeth <NUM> on its lower edge which can be engaged by a moving rack, lead screw or other such gearing within the housing <NUM>.

<FIG> shows the crimping mechanism <NUM> exploded. An array <NUM> of the linkage plates <NUM> and cooperating compression plates <NUM> (see <FIG>) includes at least <NUM>, and preferably at least <NUM> of the linked plates. The array <NUM> is arranged within the cam wheel <NUM> which includes two series of the perimeter bores <NUM> within which two outer ends <NUM> of each linkage plate <NUM> are journaled for rotation. In this way, the symmetry reduces any possible misalignment forces during crimping of the prosthetic heart valve. Each end plate <NUM> has a central aperture for passage of the prosthetic heart valve into the middle of the crimping mechanism <NUM>, as well as an array of radial slots <NUM> which will be described below.

As seen best in the cutaway views of <FIG>, each linkage plate <NUM> is hinged on an inner end to a compression plate <NUM>. The inner end of each compression plate <NUM> engages one of the axially-oriented grooves <NUM> around the outside of the compressible sleeve <NUM>. The compression plate <NUM> is formed with two outer rails <NUM> that slide within the radial slots <NUM> formed in the end plates <NUM>. Rotation of the cam wheel <NUM> displaces the outer ends <NUM> of the linkage plates <NUM> such that they transition from the angled orientation shown in <FIG> to the radial orientation of <FIG>. Because the inner ends of the linkage plates <NUM> are hinged to the compression plates <NUM>, the compression plates <NUM> are forced radially inward. Engagement between the outer rails <NUM> and the slots <NUM> constrains the compression plates <NUM> for radial movement. The linked plates <NUM>, <NUM> surrounding the sleeve <NUM> thus push inward on the grooves <NUM> and compress the sleeve radially to reduce the central orifice diameter.

Although the crimping mechanism <NUM> represents an elegant solution, with a single crimping "jaw" reducing the number of moving parts and associated friction, there are limitations on the magnitude of crimping, and a series of similar crimpers may be required to reduce the size of the article in stages. Of course, if only a small amount of crimping is necessary, one crimping mechanism will be suitable.

<FIG> are perspective and cutaway views of a multi-stage crimper <NUM> with an outer housing <NUM> enclosing a series of progressively sized crimping mechanisms 204a, 204b, 204c each with a compressible "jaw. " A crimping orifice 206a, 206b, 206c for the three crimping mechanisms gradually reduces the size of a prosthetic device such as the prosthetic heart valve described above. <FIG> shows a front cover of the housing <NUM> removed to illustrate one rotating cam wheel <NUM> on the smallest crimping mechanism 204a. A lower segment of gear teeth <NUM> on the cam wheel <NUM> may be acted on by a linearly displaced rack <NUM> to rotate the cam wheel. Although not shown, the larger crimping mechanisms may also have similar cam wheels which are acted on simultaneously by the single rack <NUM>. <FIG> shows a front portion of the cam wheel <NUM> removed to expose a plurality of linked plates <NUM>, which may be the same as those described above with respect to <FIG>.

To crimp a prosthesis, it is first placed in the largest crimping mechanism 204c and the rack <NUM> displaced to reduce the size of the prosthesis a first amount. The rack <NUM> returns to its original position and the prosthesis is then transferred to the middle crimping mechanism 204b and its size is further reduced. Finally, the smallest crimping mechanism 204a reduces the size of the prosthesis to its final diameter. Although three crimping mechanisms are shown, a minimum of two stages and more than three may be used for sequentially crimping a prosthesis in this manner.

<FIG> schematically depict a still further crimping mechanism of the present application that utilizes compressible jaws <NUM>, such as a soft elastomer. The jaws <NUM> are positioned between a series of spoke-like plates <NUM> which are initially angled from the radial so as to be nearly tangential to a circle defined by the inner faces <NUM> of each of the compressible jaws <NUM>. Outer faces <NUM> of each of the jaws <NUM> are constrained so that they cannot expand radially outward. By rotating all of the spoke-like plates <NUM> together, as seen in <FIG>, the compressible jaws <NUM> are squeezed by reduction in the volume between the plates <NUM> so that they expand inward. The aggregation of all of the interfaces <NUM> defines the crimping iris, and compresses any article therewithin. Again, with compressible jaws there are limitations on the magnitude of crimping, and a series of similar crimpers may be used to reduce the size of the article in stages, as described above with respect to <FIG>. Of course, if only a small amount of crimping is necessary, a single crimping mechanism will be suitable.

It should be understood that internal components of the crimping mechanisms described herein may be formed of multiple separate connected parts, or by combining some of these parts in integral members. For example, the six guided jaws <NUM> seen in <FIG> are constrained to move with their corresponding guide members <NUM>, and thus these components could be formed as single pieces. To the contrary, certain elements can be broken up into more than one piece, such as the jaws, so as to facilitate manufacturing. This latter instance is illustrated by the crimping mechanism shown in <FIG>.

<FIG> is a perspective view of an alternative crimping mechanism <NUM> having a modified actuating mechanism and an outer housing <NUM> shown in phantom. <FIG> shows the crimping mechanism <NUM> from a different perspective and without the outer housing <NUM>, and <FIG> shows a number of internal components including inner crimping wedges <NUM> exploded.

The modified actuating mechanism again features a relatively large diameter horizontally oriented lead screw <NUM> journaled for rotation on either side of the housing <NUM> and perpendicular to a horizontal crimping axis. A motor <NUM> in the lower part of the housing <NUM> is desirably connected via a power transmission (e.g., gears or pulleys <NUM>) to drive the lead screw <NUM>. In contrast with the actuating mechanism described above with respect to <FIG>, rotation of the lead screw <NUM> causes translation of a carriage assembly <NUM> which is connected to a cam wheel <NUM> via a linkage arm <NUM>. That is, the linkage arm <NUM> is journaled for rotation at opposite ends, one on the carriage assembly <NUM> and one on an outer lever arm <NUM> of the cam wheel <NUM>. As with the earlier embodiment, the cam wheel <NUM> has two spaced apart discs <NUM> each with a lever arm <NUM>, and there are two of the linkage arms <NUM>, one driving each lever arm. This provides an extremely balanced and robust drive system which prevents binding of the moving jaw components.

This linkage arrangement provides an extended actuation arm that produces higher torque (linear translated to radial) results at the end of crimping process, where the maximal forces are needed. In other words, the stented prosthetic valve is easier to crimp at it larger diameter, and becomes progressively harder as it is constricted. As the carriage assembly <NUM> reaches the end of the lead screw <NUM>, the linkage arms <NUM> apply a large amount of torque to the cam wheels <NUM> relative to each turn of the lead screw.

<FIG> is an exploded view of the components of the assembly of the cam wheel <NUM> and jaw mechanism. The crimping wedges <NUM> are shown arranged in a generally spiral array as they would be held within a central opening <NUM> in the cam wheel <NUM>. The crimping wedges <NUM> take the place of the inner crimping wedges <NUM> of the jaws <NUM> described above with reference to <FIG>. Flanking each side of the cam wheel <NUM> is a combination of a set of six generally triangular (pie-shaped) traveler blocks <NUM> and six guide blocks <NUM>. The guide blocks <NUM> include essentially two components back-to-back: inner traveler blocks <NUM> that resemble the traveler blocks <NUM> and outer guide elements <NUM> that are similar to the Cartesian guide elements <NUM> described above. As seen in <FIG>, the six traveler blocks <NUM> and six guide blocks <NUM> mesh in the same manner as the jaws <NUM> of <FIG>. The guide elements <NUM> have linear bars <NUM> that slide within fixed guide channels (not shown) in the inner faces of the housing <NUM>. Each of the pie-shaped traveler blocks <NUM>, <NUM> mesh with adjacent blocks in a tongue-in-groove fashion to enable smooth sliding movement therebetween.

A crimping jaw assembly of the crimping wedges <NUM>, six traveler blocks <NUM> and six guide blocks <NUM> is formed via a plurality of aligned through bores and bolts <NUM>. As in the earlier version, spiral cam slots <NUM> in the cam wheel <NUM> move small cam pins <NUM> inward as the wheel rotates. The cam pins are held within bores (not shown) on the inner faces of each of the six traveler blocks <NUM> and six guide blocks <NUM> so that the blocks are forced along linear paths as constrained by the linear bars <NUM> sliding within fixed guide channels of the housing <NUM>. This is the same as was described above. The end result is that the inner tips of the crimping wedges <NUM> translate inward along radial lines to evenly crimp a stented valve therewithin.

Each crimping jaw, per se, includes an assembly of one of the crimping wedges <NUM> connected at both axial ends to a pair of either the traveler blocks <NUM> or the guide blocks <NUM>. As can be appreciated, the several components may be manufactured separately of the same or different materials and then secured together across and through the cam wheel <NUM> via the bolts <NUM>. Preferably, the crimping wedges <NUM> are formed of a relatively rigid metal, or just inner tips of the crimping wedges <NUM> may be metal. The sliding pieces may be metal or a hard plastic or resin.

The combination of previously separate parts to form the six guide blocks <NUM> illustrates the option of using fewer more complicated parts, while the exploded assembly of <FIG> shows the option of using more, less complex parts. Ultimately, the choice of which configuration depends on materials, mold cost, engineering difficulty, etc. In a preferred embodiment, an assembly including a wedge <NUM> plus either two traveler blocks <NUM> or two guide blocks <NUM> is formed as one piece, preferably defining twelve jaw assemblies.

Claim 1:
A crimping device for crimping expandable prosthetic heart valves having support frames or stents comprising:
a plurality of crimping jaws (<NUM>, 44a, 44b, <NUM>, <NUM>) in meshing engagement and circumferentially arranged around a crimping orifice (<NUM>) having a central crimping axis (<NUM>), wherein the crimping jaws (<NUM>, 44a, 44b, <NUM>, <NUM>) each comprise an assembly of a pair of spaced apart traveling blocks (<NUM>) and a radially inner crimping wedge (<NUM>, <NUM>) that extends therebetween;
a rotating cam wheel (<NUM>, <NUM>) adapted to act on the crimping jaws (<NUM>, 44a, 44b, <NUM>, <NUM>) and displace them generally radially inward, the cam wheel (<NUM>, <NUM>) including two disks (<NUM>) having spiral cam slots (<NUM>) that act on cams secured to each of the flanking traveling blocks (<NUM>) and that extend axially inward into the cam slots (<NUM>);
a stationary outer housing (<NUM>, <NUM>) containing the cam wheel (<NUM>, <NUM>) and crimping jaws (<NUM>, 44a, 44b, <NUM>, <NUM>); and
an actuation mechanism including a lead screw (<NUM>) for rotating the cam wheel (<NUM>,<NUM>);
wherein the pair of traveling blocks (<NUM>) of at least some of the crimping jaws (<NUM>, 44a, 44b, <NUM>, <NUM>) are constrained by fixed grooves in the outer housing (<NUM>, <NUM>) for movement along lines that are tangential to a circle around the central axis such that all of the crimping wedges (<NUM>, <NUM>) of the crimping jaws (<NUM>, 44a, 44b, <NUM>, <NUM>) translate inward along radial lines toward the crimping axis (<NUM>).