Patent Publication Number: US-2003225445-A1

Title: Surgical stent delivery devices and methods

Description:
[0001] This application claims the benefit of U.S. Provisional application Serial No. 60/380,804, filed May 14, 2002, entitled “SURGICAL STENT DEVICES AND METHODS,” which application is incorporated herein by reference in its entirety. 
    
    
     
       TECHNICAL FIELD  
       [0002] The present invention relates generally to devices and methods used for loading a stent into a delivery tool for placement in a body cavity. More specifically, the present invention is directed to devices and methods for storing a self-expanding stent until the approximate time of surgical placement, then loading the stent in a more compressed state into a delivery tool for controlled stent deployment.  
       BACKGROUND OF THE INVENTION  
       [0003] Tubular prosthetic devices for transluminal implantation in body canals, such as the urethra or blood vessels, for the purpose of repair or dilation are known in the art. These prosthetic devices are commonly known as stents, and can include the types of stents that are self-expanding in the radial direction with a reduction of compression force on the outer walls of the stent. One typical self-expanding stent is disclosed, for example, in U.S. Pat. No. 4,665,771 (Wallsten), which includes a radially and axially flexible, elastic tubular body of a predetermined diameter that is variable under axial movement of the ends of the body relative to each other.  
       [0004] Self-expanding stents are typically used in applications where it is desirable to minimize acute and chronic trauma to the luminal wall when implanting an intraluminal stent. Thus, a stent that applies a gentle radial force against the wall, and that is compliant and flexible when subjected to lumen movements, is preferred for use in diseased, weakened, or brittle lumens. Preferably, a stent is further capable of withstanding radially occlusive pressure from tumors, plaque, tissue hypertrophy and luminal recoil, and remodeling.  
       [0005] A delivery tool that retains the stent in its radially compressed state is often used to present the stent to a treatment site within the body, where the flexible nature and reduced radius of the radially compressed stent enables delivery to the treatment site through relatively small and curved tracts, lumens, or vessels. In such deliveries of stents, the delivery tool is typically inserted into a body opening and passed through the various body vessels to the treatment site. After the stent is properly positioned at the treatment site, the delivery tool is actuated to release the positioned stent. With the compressive force of the delivery tool removed, the stent is then able to expand within the body vessel. The delivery tool may then be removed from the body, while the stent remains in the vessel at the treatment site as an implant. Typically, the delivery tool is designed for single use, so it may be discarded after the stent is delivered.  
       [0006] Stents can generally be grouped into the three categories of metal stents, fenestrated or laser-cut polymeric stents, and radially expanding polymeric stents. Metal stents do not degrade within the body and are thus typically used in applications where a permanent stent is desired. Metal stents are further advantageous in that they do not experience significant creep or plastic deformation when stored in a compressed state for an extended period of time. Although metal stents can provide a permanent solution for the patient, if such stents need to be removed for any reason, such as in cases where the metal stent loses some of its strength and/or if the patient needs other treatments in the same area of the body, the metal stents can only be removed with additional surgery.  
       [0007] Fenestrated stents are typically formed by providing a solid tube of polymeric stent material and using a laser to cut a pattern of holes through the wall of the tube in order to create a mesh-like appearance. Fenestrated stents are often very expensive, however, due to the large amount of polymeric material that is wasted in the laser cutting process and the time-consuming process of precisely cutting the tube with a laser to create a desired pattern. These stents are often further inappropriate for a particular application due to the tendency of fenestrated stents to resist radial expansion and longitudinal compression.  
       [0008] Radially expanding polymeric stents are typically used to artificially and temporarily keep a lumen open, but due to the material from which the polymeric stents are made, these stents begin to degrade when exposed to water and are thus eventually excreted or sloughed off by the body. This degradation is typically predictable based on the material used, thereby providing an excellent means for keeping a lumen open for a relatively short, predetermined period of time, while eliminating the need to surgically remove the stent when it is no longer needed. However, polymeric stents can experience creep when deformed or compressed for a period of time, and may thus become useless if stored in a compressed state for an extended time period. In other words, polymeric stents that are stored in a compressed state for a long period of time will often lose their ability to radially expand back to a size that is useful to support a body cavity.  
       [0009] In addition to the problems associated with creep or permanent polymeric stent deformation described above, polymeric stents are susceptible to absorbing water from their surrounding environment and becoming contaminated if not properly dry-sealed in an impermeable packaging material. The packaging materials and processes involved in keeping the components and any surrounding air within the package completely dry can be expensive and time-consuming, which is particularly true for dry-sealing a relatively large device like a delivery tool having a loaded stent. Thus, when a polymeric stent that is prone to absorbing moisture is loaded into a delivery tool, the entire delivery tool including the loaded polymeric stent must be dry-sealed, even though only the stent portion of the device actually needs the extremely dry packaging. It would therefore be advantageous to package each polymeric stent separate from its delivery tool so that the stent can be loaded into the delivery tool at the approximate time the stent is to be inserted into a patient. In this type of arrangement, only the stent and its packaging need to be subjected to the expensive environmental controls required to keep the stent dry.  
       [0010] With any of the various types of stents described above, a delivery tool of some type is needed to precisely insert the stent into a body lumen of a patient. Many delivery tools are available in the art, where the delivery tools often have a handle assembly that includes a main body with a fixed rear loop handle and a moveable forward loop handle of the type described, for example, in U.S. Patent Publication No. US 2002/0183827 (Derus et al.). To deploy a stent from using this type of handle assembly, the surgeon would typically place a thumb in the rear loop handle and a finger in the forward loop handle, then pull the forward loop handle toward the rear loop handle by squeezing the inserted finger toward the thumb. While handles of this type often provide precise positioning of a stent, there is a continued need for different types of delivery tools to accommodate the preferences of a wide variety of surgeons.  
       SUMMARY OF THE INVENTION  
       [0011] The present invention is directed to methods and devices by which a stent may be loaded into a delivery tool prior to its implantation within a patient. In particular, the present invention is directed to the radial compression of a self-expanding stent to reduce its diameter from its storage state, then transferring the compressed stent into a delivery tool. Drawing the stent from a storage area or chamber of a cartridge through a funnel section and into a transfer or loading chamber that is smaller than the storage chamber preferably accomplishes the radial compression of the stent. In one aspect of the invention, one or more sutures or threads may be attached to the stent and positioned so that the threads extend through the body of the cartridge and are accessible to the person desiring to load the stent into a delivery tool. The stent is then pulled, preferably by the attached threads, from the storage area to the transfer chamber until the stent is generally enclosed within the transfer chamber. After the stent is in this transfer chamber, the threads can be cut, if desired, then the delivery tool can be introduced into an opening in, and generally concentric with, the end of the cartridge where the stent had previously been stored. When the delivery tool is properly positioned within the cartridge, a plunger or other transfer mechanism is activated to drive the stent into the delivery tool. At this point, the delivery tool can be removed from the cartridge and used to implant the stent in a body cavity.  
       [0012] The devices and methods of the present invention offer a number of advantages over certain prior art systems. For example, the present invention provides devices, methods, and systems that require relatively few, uncomplicated components that can accommodate a wide range of stent sizes. The cartridges may function independently of a delivery system and may be used multiple times, if desired. Further, when a degradable stent is used, the methods and devices of the present system require a relatively small amount of dry storage volume as compared to systems that use dry storage for the delivery tool and stent in combination.  
       [0013] The present invention further provides a handle design that provides a mechanism for a stent delivery tool that improves the mechanics of the delivery system, simplifies the design, is usable for a wide range of stent sizes, and promotes smooth, consistent, and controlled operation. In particular, the invention provides a delivery tool having a handle that incorporates a slider linkage, such as a 4-bar slider linkage, where a pivot point of the linkage is located on the axis of a concentric inner and outer tubing of the delivery tool. In this way, the moment load to these components may be minimized, and the potential for binding to occur between the components is also reduced. These features can be beneficial to a surgeon by providing a tool with improved tactile feedback, better placement precision, and reduced time and difficulty in deploying the stent. With regard to manufacturability of the delivery tool, the present handle requires relatively small assembly time and uses a small number of parts. The handle design is further advantageous in that it is adaptable to multiple linkage configurations and locking systems, where the ability to change linkage configurations can make the basic design applicable to other applications. The tool may further include a locking system to prevent and allow relative movement of the components during the various stent loading and deployment or implantation processes, as desired. The handle design may instead include a V-shaped handle and/or may include springs or other mechanisms that allow precise handling and placement by a surgeon during an implantation process.  
       [0014] In one aspect of this invention, a device is provided loading a self-expanding stent into a receiving area of a delivery tool. The device comprises a stent storage region having an internal chamber sized to retain the stent in a first state, a stent transfer region spaced from the storage region and having an internal chamber sized to receive, retain, and transfer the self-expanding stent in a second state in which the stent is at least partially compressed relative to the first state of the stent, and a stent compressing region extending between the storage region and the transfer region and having an internal chamber for radially collapsing the stent from the first state to a second state. The device further comprises a loading mechanism slideably positioned relative to the transfer region for slideably moving the stent in the second state from the transfer region toward the compressing region.  
       [0015] The device may further comprise a stent transfer mechanism for moving the stent from the storage region to the transfer region through the compression region while compressing the stent from the first state to the second state, wherein the stent transfer mechanism may include an extending member that is moveable from the storage region to the transfer region. The stent transfer mechanism is may be attached to a portion of the stent in such a way that it can be removed. The extending member of the stent transfer mechanism may be a generally flexible material and may specifically be made of a thread-like material. The loading mechanism of the device may include an extending portion having a distal end that is engageable with a portion of the stent to slideably force the stent in the second state from the transfer region toward the compressing region. The device may further comprise a spool insert positioned at least partially within the internal chamber of the storage region, wherein the spool insert is sized to support an interior portion of the stent provided in the first state.  
       [0016] The device described above may further be provided in combination with a self-expanding stent provided in the first state within the internal chamber of the storage region, wherein the stent comprises a substantially tubular, radially expandable body portion. The device described above may also be provided in combination with a delivery tool comprising an outer tube and an inner tube, wherein the outer tube is slideable relative to the inner tube, and further comprising a receiving area inside the outer tube and adjacent a first end of the outer tube, wherein the outer tube of the delivery tool may be sized to be inserted into the internal chamber of the storage region and the internal chamber of the compressing region of the device.  
       [0017] In another aspect of the invention a method is provided of loading a self-expanding stent into the receiving area of a loading tool, the method comprising the steps of providing a stent cartridge comprising a stent storage region having an internal chamber including a stent in a first state, a stent transfer region spaced from the storage region and having an internal chamber sized to receive, retain, and transfer the self-expanding stent in a second state in which the stent is at least partially compressed relative to the first state of the stent, a stent compressing region having an internal chamber extending between the storage region and the transfer region, and a loading mechanism slideably positioned relative to the transfer region. The method further comprises moving the stent from the internal chamber of the storage region through the internal chamber of the compressing region to the internal chamber of the transfer region, wherein the stent is compressed to the second state, then inserting a first end of a delivery tool through an end of the stent storage region and into the stent compressing region, the delivery tool comprising an outer tube having a first end and an inner tube positioned within the outer tube, wherein the outer tube has a receiving area adjacent to the first end, and wherein the inner tube is slideable relative to the outer tube. The method also includes transferring the stent in the second state from the transfer region of the cartridge into the receiving area of the delivery tool by moving the loading mechanism toward the compressing region. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018] The present invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein:  
     [0019]FIG. 1 is a perspective view of a stent of the type that can be used in conjunction with the methods, devices, and systems of the present invention;  
     [0020]FIG. 2 is a cross-sectional side view of a stent cartridge or device of the present invention, including a stent in its expanded state within a storage region of the device;  
     [0021]FIG. 3 is a cross-sectional side view of the stent cartridge of FIG. 2, with the further inclusion of a portion of a delivery tool inserted therein, and including a loading mechanism in a retracted state and a stent in its compressed state;  
     [0022]FIG. 4 is a cross-sectional side view of the stent cartridge of FIGS. 2 and 3, with the stent inserted into the end of the delivery tool;  
     [0023]FIG. 5 is a cross-sectional side view of an alternative stent cartridge in accordance with the present invention;  
     [0024]FIG. 6 is a side view of one embodiment of a delivery tool for stent placement and delivery;  
     [0025]FIG. 7 is perspective view of another embodiment of a delivery tool for stent placement and delivery;  
     [0026]FIG. 8 is a perspective view of another embodiment of a delivery tool for stent placement and delivery; and  
     [0027]FIG. 9 is a side view of a delivery system for stents including a stent cartridge and a loading tool similar to that illustrated in FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0028] Referring now to the Figures, wherein the components are labeled with like numerals throughout the several Figures, and initially to FIG. 1, one preferred configuration of a stent  20  in accordance with the present invention is illustrated. This exemplary stent or prosthetic device  20  has a flexible, generally tubular shape and generally comprises a plurality of interwoven or interconnected fibers or wires  22  defining a series of interconnected cells or openings  24  between the fibers  22 . The fibers  22  may be arranged so that one or both ends of stent  20  include a series of loops  26  around the periphery of the stent or may include a series of loose fiber ends. It is further preferable that the stent  20  is of the type generally known as a self-expanding stent. The length of the stent  20  may range from about 10 mm to about 500 mm, preferably from about 10 mm to about 50 mm, with the relaxed diameter ranging from about 4 mm to about 45 mm, preferably from about 5 mm to about 25 mm.  
     [0029] Self-expanding stents, as referred to herein, are devices that can be radially compressed from their relaxed state when subjected to external forces, but can spring or expand at least partially back toward their relaxed state when the external forces are removed or reduced. In particular, self-expanding stents are typically devices that are either initially provided with a relatively low cross-sectional profile or radius, or are compressed to such a cross-sectional profile, for insertion into a small tubular body lumen, such as a urethra, for example. This lower cross-sectional profile can be particularly advantageous in situations where it is necessary to deliver the stent through relatively small and curved tracts, lumens, or vessels. When the stent is inserted and properly positioned within the body, the external forces on the stent may be removed to allow it to expand to a larger diameter, thereby providing the necessary support to the lumen in which it is inserted. Due to the geometry of the stent, the stent will typically be longer when in its compressed state and shorter when in its expanded state. Thus, devices that are similar to that of stent  20  are preferably made of materials that will expand to predictable dimensions upon their insertion into a body organ, and then retain those same dimensions for an extended period of time to continuously provide the desired support for the body organ, such as to prevent that body organ from collapsing or constricting. That is, the stents used with the present invention are preferably made of materials having a high modulus of elasticity so that they can be compressed to a relatively small diameter when subjected to various forces that cause it to constrict, then spring back a specified amount when the various forces are removed or reduced.  
     [0030] While the devices and methods of the present invention are applicable to a wide variety of stent configurations and materials, the present invention provides particular advantages for implantation of stents that permanently or plastically deform to some degree when subjected to external forces for a period of time, such as when compressed. With materials of this type, it is often advantageous to minimize the amount of time that the stents are compressed to reduce the probability of the stent taking a “set” or permanently deforming to such a degree that it cannot sufficiently expand back toward its original, uncompressed state when the external forces are removed. Such stent materials include, for example, bioresorbable, biocompatible polymeric materials such as hompolymers, copolymers, and blends of two or more homopolymers or copolymers, optionally including additives. A polymeric, bioresorbable stent may be of any stent configuration, such as a stent comprising woven, extruded monofilaments, or a stent comprising an extruded and cut fenestrated, self-expanding stent. Examples of bioresorbable stents and their materials and methods of their manufacture can be found, for example, in U.S. Pat. No. 6,368,346, the disclosure of which is incorporaed herein by reference. Exemplary polymeric materials include poly-L-lactic acid (PLLA), poly-D,L-lactic acid (PDLA), poly-e-caprolactone (PCL), and similar polymers. One preferred polymeric material for a bio-resorbable, biocompatible stent can be a blend of PLLA and PCL, e.g., in a ratio of 80:20 to 99:1 (PLLA:PCL). It is contemplated, however, that the devices and methods of the present invention are equally adaptable to stents made of materials that do not experience any appreciable creep or permanent deformation when stored in a compressed state for extended periods of time, such as stents made from a plurality of interwoven metal fibers or wires.  
     [0031] Referring now to FIG. 2, one preferred embodiment of a stent cartridge or device  30  is shown, which generally includes a body  32  having a stent storage region  34 , a stent compressing region  36 , and a stent transfer region  38 . The device  30  includes an internal chamber  40  that extends from a proximal end  42  of the body  32  adjacent the storage region  34  to a distal end  44  adjacent the transfer region  38 . Device  30  is further shown with a stent  46  in its uncompressed state within the storage region  34 . As will be described in further detail below, this stent  46  can be moved between the various regions of the body  32  to provide the desired stent compression and loading into a delivery tool in accordance with the present invention. In particular, the internal chamber  40  of the storage region  34  is preferably sized to be large enough to retain a particular stent in its natural or uncompressed state without any unnecessary or undesired compressive forces being applied to the outside of the stent. It is contemplated, however, that the stent  46  may be partially compressed when in the storage region  34 . Further, the storage region  34  should extend far enough in the longitudinal direction of the device  30  to retain the entire length of a stent being stored therein. That is, when a stent is being stored within the device  30 , it will preferably not extend into the compressing region  36  or any part of the body  32  in which the stent would be subjected to compressive forces that cause permanent stent deformation and will instead be contained within the storage region  34 .  
     [0032] As shown, the stent compressing region  36  extends between the storage region  34  and the transfer region  38 , and is generally funnel-shaped such that the compressing region  36 , as shown, is shaped as a truncated conical section. In this embodiment, it is not necessary that the compressing region  36  is long enough to retain the entire length of a stent  46  at any particular time; however, it is preferable that the compression region  36  is sufficiently long that the radius reduction of the internal chamber  40  in this section is relatively gradual. In particular, the compression region  36  is preferably provided with sufficient length that stent  46  can move easily through the device  30  while being subjected to relatively gradual compressive forces that do not undesirably deform or otherwise damage the stent. In any case, the internal chamber  40  of the compression region  36  is sized for radially collapsing the stent  46  from an expanded state to the compressed or partially compressed state in which it will be held within the transfer region  38 . It is preferable that the walls of the compressing region  36  taper at a constant angle from the storage region  34  to the transfer region  38  to provide a consistent reduction of the internal radius of the internal chamber  40  in the compressing region  36 . However, the reduction of the internal radius of the compressing region  34  may instead include a variety of tapered sections, where some sections include a different slope or taper than other sections within this region. Alternatively, stepped or less consistent dimensional changes of the compression region  34  may be provided.  
     [0033] Stent  40  is preferably provided with at least one transfer mechanism, such as one or more threads or sutures  52  of the type illustrated in FIGS. 2 and 3, for facilitating the transfer of the stent  46  from the storage area  34  to the transfer area  38 . The threads  52  can be attached to the stent  46  in any number of ways, such as with adhesives, hooks, or the like. In one preferred embodiment of the invention, the thread or threads  52  are inserted through one or more openings in the stent  46 , such as the openings  24  of the stent shown in FIG. 1, or such as the loops  26  at one end of the stent when such loops are provided. The threads  52  can be attached to the stent at any point or points along the length of the stent that allow the stent to be stretched or pulled without breaking or substantially deforming the fibers of the stent. Thus, if the force required to pull the stent is higher than the force that the stent fibers near the end of the stent can withstand without breaking or unraveling, the thread  52  should be attached to the stent at a point or points that are spaced some further distance from the ends of the stent. Preferably, the threads  52  are attached as close to the end of the stent that will be pulled as possible to cause extension of the stent while it is being compressed through the compressing region.  
     [0034] In one arrangement, a single thread  52  is attached to a stent  46 , wherein a thread  52  is inserted through a hole or opening in one side of the stent  46  at a point that is near the end of the stent  46  that will be pulled, then extended across the center of the stent  46  to approximately the diametrically opposite side of the stent  46 . The thread  52  can then be inserted through a hole in this side of the stent  46  and pulled through the stent  46  until the extending portion of the thread  52  is long enough to be used for transfer of the stent  46  within the device  30  in accordance with the methods of the present invention. In many cases, a single thread  52  will be sufficient to accomplish the necessary transfer of the stent. However, additional threads  52  can be similarly attached at various points around the stent, if desired, to better distribute the forces that will be imparted to the stent when it is pulled. In a configuration of this type, the threads  52  may cross over each other in the center area of the stent or may not cross each other if multiple threads are inserted in holes in the stent that are not diametrically opposite each other. It is also contemplated that a single thread  52  may be used that is woven through multiple holes or loops around the perimeter of the stent, which can also serve to distribute the forces to multiple fibers or wires of the stent when it is pulled to further minimize the possibility of stent fiber breakage and/or deformation. The material from which the threads or sutures  52  are made should be sufficiently strong that they will not break or stretch when pulling the stent from the storage region  34  to the transfer region  38 .  
     [0035] With further reference to FIG. 2, when the stent  46  is loaded or stored within the storage region  34  of the device  30 , the thread or threads  52  attached to the stent  46  are positioned to extend through the compression region  36  and transfer region  38  and beyond the distal end  44  of the device  30 . To move the stent  46  into the transfer region  38 , the threads  52  extending from the distal end  44  are pulled in a direction A to move the stent through the compression region  36  and into the transfer region  38 . Referring also to FIG. 3, the transfer region  38  is preferably sized to receive and retain a stent  46 , such as a self-expanding stent, in a relatively compressed state in which the stent has a smaller radius as compared to the expanded or uncompressed state of the stent. In particular, FIG. 3 shows the stent  46  in a relatively compressed state and extending only within the transfer region  38 . As with the storage region  34 , the transfer region  38  preferably extends far enough in the longitudinal direction of the device  30  to contain the entire length of a stent in its compressed state when being held therein, as shown in FIG. 3. That is, when a stent is compressed to a predetermined size and is moved into the transfer region  38 , it will preferably not extend into the compressing region  36  such that the entire stent is retained within the transfer region  38  in its compressed state. Although it is possible that a portion of the stent extends beyond the transfer region  38 , any portion of the stent that extends into the compression region  36  will tend to expand to be a larger diameter than the portion of the stent within the transfer region, which may complicate the process of loading the stent into a delivery tool.  
     [0036] The transfer region  38  is preferably also provided with a loading member or plunger  50  positioned therein that is moveable or slideable in the longitudinal direction of the device  30 . In this embodiment of the invention, the loading member  50  includes an elongated body portion  54  and a cap  56  at one end of the body portion  54 . The body portion  54  and cap  56  are preferably provided with an elongated opening  58  extending from one end of the loading member  50  to the other. The body portion  54  is also preferably sized so that the loading member  50  can slide relatively easily with respect to the transfer region  38  in which it is provided. In particular, the loading member  50  can be positioned within the transfer region  38  when the stent  46  is in the storage region  34 , but can preferably move a sufficient distance out of the storage region  34 , in direction A, to provide enough space to accommodate the entire stent  46  in its compressed state within the region  38 . The loading member  50  is also moveable back into the transfer region  38  by applying sufficient force on the cap  56  to push the stent  46  toward the compression region  36 , when desired. Thus, this transfer region  38  is designed and sized to receive, retain, and transfer a stent in its compressed or partially compressed condition. In any case, the inside chamber  40  of the transfer region  38  preferably has cross-sectional dimensions that are equal to or slightly smaller than the internal dimensions of a loading tool or device into which the stent will be loaded, the advantages of which will be described in further detail below. In addition, the inside of the transfer region  38  near the distal end  44  and/or the outside of the body portion  54  may be provided with a shoulder portion or other configuration that acts as a stop to keep the loading member  50  from being pulled completely from the end  44  of the device  30 . When such a configuration is used, the loading member  50  should preferably be able to move out of the transfer region  38  a sufficient distance to allow containment of a compressed stent therein.  
     [0037] As described above, moving the stent  46  from the storage region  34  to the transfer region  38  is preferably accomplished by pulling threads  52  attached to the stent. These threads are not necessarily attached to any other components of the device  30 ; however, the threads can be attached to the loading member  50  so that pulling the cap  56  of member  50  will simultaneously pull the threads  52  attached to the stent  46  within the device. In one embodiment of the invention, the elongated opening  58  in the body portion  54  is sized to accommodate one or more threads passing from one end of the loading member  50  to the other. In this arrangement, the threads  52  can extend from the stent  46  in the storage region  34 , through the compressing region  36 , through the entire length of the opening  58  of the loading member  50 , and then extend beyond the distal end  44  of the device  30 .  
     [0038] The motion of the threads  52  pulling the stent  46  and the motion of the loading member  50  sliding out of the transfer region  38  may occur simultaneously or may be independent operations. For example, if the threads  52  are not attached to the loading member  50 , the loading member  50  may first be retracted from the transfer region  38  by a distance to allow sufficient space to contain a compressed stent, then the threads  52  attached to the stent  46  may be pulled to move the stent  46  into the transfer region  38 . In another example of an arrangement where the threads are not attached to the loading device  50 , the threads  52  that extend through the opening  58  can be pulled to move the stent  46  into the transfer region  38 , which simultaneously forces the loading member  50  to slide in the direction A until the stent is contained within the transfer region  38 . In this case, the loading member  50  should slide within the transfer region  38  sufficiently easily that when the stent  46  is pulled via the threads  52 , the stent  46  itself can force the member  50  from the internal chamber of the transfer region  38  without damaging the stent. In another example in which threads  52  are attached in some way to the loading member  50 , either pulling either the threads  52  that extend past the end of the device  30  or pulling the cap  56  of the loading member  50  will simultaneously move the loading member  50  in the direction A and pull the threads  52  and attached stent  46  in the direction A.  
     [0039] To facilitate easier grasping of threads  52  extending from the distal end  44  of the device  30 , particularly when such threads  52  are not attached to loading member  50 , the threads  52  can optionally be attached to a device such as a ring  60 , as shown in FIGS. 2 and 3. Many alternative devices or arrangements may be used in place of the ring  60 , such as a bar or some other device that is preferably larger than the interior dimensions of the opening  58  of the loading member  50  to maintain the threads  52  in a position outside the device  30 . In this way, the stent  46  can be pulled from the storage region  34  by grasping and pulling the device attached to the threads  52 , such as the ring  60 , to cause the loading member  50  to retract from the transfer region  38 .  
     [0040] Alternatively, a mechanism other than threads or sutures can be used to transport the stent to the transfer region, such as a relatively flexible elongated member with hooks or other means of grasping the stent to pull it into the transfer region. This alternative to the threads would preferably also be relatively thin and elongated so that it can extend from the stent to which it is temporarily or permanently attached and through the end of the device opposite the transfer region thereof. The mechanism would preferably also be thin enough that it can extend through the opening in the body of a loading member, when such a configuration is used. The mechanism used in such a way is preferably also relatively easy to sever or otherwise detach from the stent when desired in the process of loading the stent into a delivery tool and/or for implantation of the stent in a patient.  
     [0041] After the stent  46  has been compressed and is being held within the transfer region  38 , it is preferable that the stent  46  be transferred to a delivery tool so that it can be placed in a predetermined location within a patient. If the stent  46  is made of a polymeric material, it is further preferable that the stent be compressed and quickly transferred to a delivery tool for relatively immediate deployment thereof. In this way, any plastic deformation of the stent within the transfer region  38  can be minimized or avoided. Referring particularly to FIGS. 3 and 4, once the stent  46  is compressed and contained in the transfer region  38 , it can be transferred to or loaded into a wide variety of delivery tools that are used for implantation of the stent in a desired location within a body cavity. In particular, the illustrated portion of the delivery tool shown includes an outer tube  70  and a generally concentrically located inner tube  72 , where a distal end  74  of the outer tube  70  is positioned adjacent to the transfer region  38 . In particular, the outer tube  70  is inserted into the proximal end  42  of the device  30 , through the storage region  34  and the compressing region  36  until it reaches the transfer region  38 . While it is preferable that the outer tube  70  of the delivery tool is sized so that it can be inserted through the entire length of the device  30  until it reaches the transfer region  38 , the distal end  74  of the outer tube  70  may instead be spaced from the transfer region  38  and the stent  46  contained therein. In any case, it is preferable that the distal end  74  of the outer tube  70  is positioned close enough to the transfer region  38  that the compressed stent  46  can be transferred into the outer tube  70  without substantially expanding upon movement from the transfer region  38 , as described in further detail below.  
     [0042] As shown, the inner tube  72  is retracted relative to the outer tube  70  to thereby provide a receiving area  76  adjacent the distal end  74  of the outer tube  70 . In particular, the receiving area  76  extends from the distal end  74  of the outer tube  70  to a distal end  78  of the inner tube  72 . The receiving area  76  preferably has a sufficient length to receive all or most of the length of the stent to be inserted therein. To move the compressed stent  46  from the transfer region  38  into the receiving area  76  of the delivery tool, the loading member  34  is pushed in a direction B until the stent  46  is completely or substantially contained within the end of the receiving area  76 , as shown best in FIG. 4. The device  30  may then be removed from the outer tube  70  so that the compressed stent  46  may be deployed from the delivery tool when desired.  
     [0043] Outer tube  70  is preferably strong enough to maintain a stent being contained therein in its compressed state, yet in some cases, the outer tube  70  is also preferably flexible enough to allow sufficient maneuvering of the delivery tool within a body cavity to implant the stent. When flexibility of the outer tube  70  is desired, the tube  70  may be made of a high strength thermoplastic elastomer such as nylon, PTFE, polyvinylchloride, or the like, for example. Alternatively, if such flexibility of the outer tube  70  is unnecessary or if it desirable to provide an outer tube with additional strength, a more rigid material may be used for the outer tube  70 , such as stainless steel, for example.  
     [0044] Inner tube  72  is smaller in diameter than the outer tube  70  and may be formed of the same or a different material than the outer tube  70 . It is preferable that the inner tube  72  can slide relatively easily within the outer tube  70  to allow for smooth deployment of the stent when desired. In particular, the outer tube  70  and inner tube  72  are moved relative to each other during stent deployment to reduce the length of the receiving area  76  so that the distal end  78  of the inner tube  72  holds the stent in place while the outer tube  70  retracts to expose the stent. Preferably, the outer tube  70  can be moved a sufficient distance relative to the inner tube  72  that the distal end  74  of the outer tube  70  can move far enough toward the distal end  78  of the inner tube  72  to allow the stent to entirely separate from the outer tube  70 . In this way, the receiving area  76  will be eliminated and the entire length of the stent  46  will be released from the distal end  78  of the outer tube  70 . However, it is contemplated that the outer tube  70  may remain partially retracted relative to the inner tube  72  during stent deployment so that the final portion of the stent is separated from the outer tube  70  by movement of the outer tube  70  in a direction opposite that of the movement of the stent into the body cavity.  
     [0045] In one preferred embodiment, the inner tube  72  is hollow and is made of a material that has sufficient strength to push the compressed stent from the receiving area  78  of the delivery tool without significant deformation of the inner tube  72 . In addition, when the inner tube  72  is hollow, the walls of the tube material are preferably thick enough that a stent being held in the receiving area cannot slip into the interior portion of the inner tube  72  at any point in the stent compression and deployment process. In many cases, it may be desirable for the inner tube  72  to be hollow to allow for the passage of a small device or element (e.g., endoscopes or other viewing equipment, balloon delivery devices to facilitate stent expansion, and the like) through the center of the inner tube  72 . A hollow inner tube  72  may further be advantageous if a stent that is not self-expanding is used, wherein a balloon catheter or other device may be inserted through the inner tube  72  and used to expand the stent, when desired. However, if the inner tube  72  is hollow, it may include a cap or end portion (not shown) that covers the distal end  78  of the inner tube  72 , or the inner tube  72  could alternatively consist of a solid piece of material. In either of these cases, the likelihood is eliminated of a stent moving into the inner tube  72  at any point during the stent compression and deployment process.  
     [0046] When a device, such as device  30 , includes a stent with attached threads, the threads or other extending members can be cut or removed from the stent at any time after the stent is moved into the transfer region, such as immediately after the threads are used to pull the stent into the transfer region of the device. Alternatively, the threads can remain attached to and extending from the compressed stent until the stent is moved from the transfer region into the delivery tool; however, it is preferable that the threads be removed or cut before deployment of the stent by a surgeon. As an alternative to using the threads or sutures attached to a stent, or in conjunction with using threads or sutures attached to a stent to transfer a stent from a storage region to a transfer region, it is contemplated to use a different device to push the stent from the storage region, through the compressing region, and into the transfer region. This could be accomplished, for example, using a relatively flexible material that can compress within the compression region along with the reduction in cross-sectional dimensions of this area.  
     [0047] Referring again to FIGS. 2 through 4, the stent storage region  34  may include a spool insert  80  for retaining the stent in its desired location within the device  30 , and also to prevent the stent  46  from compressing or collapsing to a radial dimension that is smaller than that provided by the outside of the spool. In particular, the spool  80  includes a cylindrical support portion  82 , a shoulder portion  84 , a cap portion  86 , and an opening  88  that extends generally through the center of the spool  80  from the cap portion  86  through the support portion  82 . The support portion  82  is preferably cylindrical and has an outer diameter that is approximately equal to the inside diameter of the stent  46  in its relaxed state. The support portion  82  is also preferably long enough to support the entire length of the stent  46  in its relaxed position. In this way, no portion of the stent  46  will constrict to a diameter smaller than the outside diameter of the support portion  82  until it is desired to move the stent  46  toward the transfer region  38 , in accordance with the present invention. The opening  88  through the spool  80  is preferably cylindrical and large enough to accept the outer tube of a delivery tool that is inserted without requiring excessive force for the insertion. In order to retain the spool  80  within the storage region  34 , the shoulder portion  84  preferably has an outer diameter that is slightly smaller than the inside diameter of the proximal end  42  of the device to provide a relatively tight interference fit between these surfaces when the spool  80  is inserted therein. Finally, the cap portion  86  preferably has an outer diameter that is at least slightly larger than the inside diameter of the proximal end  42  of the device  30  to limit the movement of the spool into the storage region  34 .  
     [0048] To load a stent  46  into the device  30 , the stent  46  is positioned on the support portion  82 , which is inserted into the proximal end of the device  30  until the shoulder portion  84  is positioned a sufficient distance into the device  30  that it will not unintentionally be dislodged from the device. Preferably, the shoulder portion  84  is pushed into the interior of the device  30  until the cap portion  86  contacts the distal end  42 . The spool  80  is preferably removable and replaceable for reuse of the device  30  with additional stents, if desired. It is understood that the spool  80  could alternatively be omitted from the device  30 , that another type of device for supporting a stent could be used, or that a stent may be placed in the storage region  34  without any stent support. In any of these alternatives, a cap may still be placed on the end of the device to keep the stent contained within the device.  
     [0049]FIG. 5 illustrates another embodiment of a cartridge assembly  400  in accordance with the present invention, which is somewhat similar in structure to the device  30  described above. In particular, assembly  400  includes a cartridge barrel  402  that includes a storage region  404 , a compressing region  406 , and a transfer region  408 . A stent  410  is stored or held within the storage region  404 , wherein the stent  410  includes at least one extending member  412 , such as a thread, wherein the extending member  412  extends through the length of the barrel  402  and through its distal end  414 . In this embodiment, the transfer region  408  of the barrel includes a first portion  416  extending from the compressing region  406  and a second, removable portion  418  that extends from the first portion  416 . The removable portion  418  preferably includes a shoulder  420  to stop the compressed stent  410  from being pulled through the distal end  414  of the barrel  402  when the extending member  412  is pulled to move the stent into the transfer region  408 . The removable portion  418  further includes a section  422  having a smaller diameter than rest of the portion  418 . Section  422  preferably includes at least one protrusion  423  that may extend around part or the entire periphery of the section  422 .  
     [0050] To load the stent  410  into a delivery tool, the attached extending member  412  is pulled to move the stent  410  through the storage and compressing regions and into the transfer region  408  until it reaches the shoulder  420 . The extending member  412  may then be cut or otherwise removed from the stent  410 . The removable portion  418  of the transfer region  408 , which is designed to be relatively easily removed from the remainder of the barrel  402 , may then be detached from the first portion  416 . In one example, the portions  416  and  418  are attached to each other in such a way that turning these portions relative to one another causes allows them to separate. Any other known arrangements of connecting and detaching two tubular sections may be utilized, as desired. In any case, the removable portion  418  will then contain the compressed stent  410  and will be a separate component from the remainder of the cartridge assembly  400 .  
     [0051] The removable portion  418  with the compressed stent  410  may then be attached to the end of a delivery tool, a portion of which is shown in FIG. 5. In particular, the end of the delivery tool includes an outer tube  430  having at least one recess  432  that generally corresponds with the protrusion  423  of the section  422 , and an inner tube  434 . The outer tube  430  is then pressed over the section  422  until the protrusion  423  is positioned within the recess  432 , thereby securing the two components to one another. In this embodiment, the stent  410  is then ready for deployment by retracting the outer tube  430  to expose the stent  410  from the end of theremovable portion  418  to a desired location within a body cavity.  
     [0052] Delivery tools used with the stent cartridges of the present invention for stent placement and deployment may have any number of handle configurations, such as those prior art delivery tools having a handle assembly that includes a main body with a fixed rear loop handle and a moveable forward loop handle of the type described, for example, in U.S. Patent Publication No. US 2002/0183827 (Derus et al.), commonly owned by the assignee of the present invention, the entire contents of which are incorporated herein by reference. To deploy a stent from using this type of handle assembly, the surgeon would typically place a thumb in the rear loop handle and a finger in the forward loop handle, then pull the forward loop handle toward the rear loop handle by squeezing the inserted finger toward the thumb. Although it is preferable that the delivery tools used with the stent cartridges of the present invention include a receiving area for the stent within an outer tube of a catheter assembly, it is contemplated that other types of delivery tools that have different configurations for receiving a compressed stent may be used.  
     [0053] In accordance with the present invention, embodiments of handle configurations that are preferably attached to an end of a catheter assembly opposite a stent deployment end are described below. These handle assemblies each involve the use of multiple arms or linkages that can pivot or rotate about each other, with at least one of the arms being provided with a relatively large gripping area for the fingers of a surgeon or other person implanting a stent loaded in the delivery tool. In addition, another arm is preferably spaced at an appropriate distance from the arm having the gripping area so that a surgeon can easily grasp both arms and squeeze them toward each other for precise deployment of a stent. It is further desired with any of the handle assemblies that a stopping device of any appropriate configuration can be used to keep the various handle portions from moving too far from each other before stent deployment. Such a stopping device is preferably designed to provide a retaining area of at least a sufficient size to hold the length of a compressed stent therein. In addition, where rotation points or pivot points are described, it is understood that the movement can be generally unobstructed to allow for smooth rotation, or these points may include a ratcheting mechanism that provides a more “stepped” type of motion for the components relative to each other.  
     [0054] Referring now to FIG. 6, a preferred embodiment of a delivery tool  100  in accordance with the present invention is shown. The delivery tool  100  generally comprises a handle assembly  102  and a catheter assembly  104  extending from the handle assembly  102 . The catheter assembly  104  preferably comprises an elongated outer tube  106  and an elongated inner tube  108  slideably positioned within the outer tube  106 . The outer tube  106  is preferably at least partially retractable and extendable relative to the inner tube  108  so that a receiving area  110  is provided generally at a distal end  112  of the outer tube  106  for receiving a stent when the outer tube  106  is at least partially extended relative to the inner tube  108 . In addition, the outer tube  106  can preferably be retracted or moved a sufficient distance relative to the inner tube  108  to adequately reduce the size of the receiving area  110  to facilitate deployment of the stent.  
     [0055] As described herein, the various tubes of the delivery tool, such as the inner tube  108  and the outer tube  106 , may comprise a single tubular piece, or may instead include multiple pieces that are attached to each other but perform functionally as a single unit. The use of multiple pieces for a single tube component may be advantageous, for example, for the inner tube  108  of the delivery tool  100  so that the portion nearest the handle assembly  102  can be provided with greater strength and rigidity than the portion that extends therefrom that will contact the stent. The use of different materials may also be advantageous to minimize the overall weight of the tool, such that pieces or portions that do not require significant strength can be made of a relatively light material.  
     [0056] As shown, the handle assembly  102  includes a first handle portion  114  attached near one end of the inner tube  108 . As shown, the inner tube  108  of the catheter assembly  104  is engaged with a receiver  115  of the first handle portion  114 . In one embodiment, the inner tube  108  can rotate with respect to the receiver  115  (especially if a locking device is used as described below) but cannot otherwise move with respect to the receiver  115 . That is, the inner tube  108  is linearly fixed with respect to the first handle portion  114 .  
     [0057] The first handle portion  114  further includes a first pivot point  118  spaced from the receiver  115 , at which point a linking arm  120  is pivotally connected to the first handle portion  114 . The linking arm  120  is further pivotally connected at a second pivot point  122  to a gripping arm  124 . Gripping arm  124  is preferably designed so that a body portion  126  thereof is large enough to accommodate at least two fingers, and preferably four fingers, of a hand of an operator such as a surgeon, and may include indentations or other contours (not shown) for the fingers of the surgeon, if desired. In any case, the gripping arm  124  is arranged so that an end thereof that is spaced from the second pivot point  122  includes a sleeve  123  attached at a third pivot point  125 . The sleeve  123  fixedly engages the outer tube  106  of the catheter assembly  104  such that the outer tube  106  cannot rotate or move linearly with respect to the sleeve  123 . The sleeve  123  also slideably engages the inner tube  108 . As such, the gripping arm  124  can be actuated to translate the outer tube  106  with respect to the inner tube  108  by the linkage comprising the first handle portion  114 , linking arm  120 , and gripping arm  124 .  
     [0058] Optionally, the delivery tool  100  may comprise the ability to lock the inner tube  108  with respect to the outer tube  106  such as is generally desired during insertion of the catheter device  104  into a body lumen for deployment of a stent. For one example, as shown in FIG. 6, the delivery device  100  includes a knob  128  attached to the inner tube  108  for rotating the inner tube  108  with respect to the receiver  115 , the sleeve  123 , and outer tube  106 . Preferably, the sleeve  123  includes a spring-loaded extendable portion such as a pin or the like (not shown) that can engage with a recessed portion of the inner tube  108 . For another example, grooves and/or tabs can be provided on various components in the systems to selectively allow and prevent movement of an inner tube with respect to an outer tube. Alternatively, any locking device that locks the inner tube  108  with respect to the outer tube  110 , such as a device that locks the handle assembly  102  in place, may be used.  
     [0059] Further referring to FIG. 6, the delivery tool  100  is shown in a position in which the outer tube  106  of the catheter assembly  104  is extended enough to provide a sufficiently large receiving area  110  to accommodate a compressed stent. In this position, the sleeve  123  of the gripping arm  124  is spaced apart from the receiver  115  of the first handle portion  114 . When it is desired to deploy the stent, the gripping arm  124  is pulled toward the first handle portion  114 , thereby retracting the outer tube  106  relative to the inner tube  108  and reducing the length of the receiving area  110 . As this length is further reduced, the stent continues to be pushed or moved from the distal end  112  of the outer tube  106 .  
     [0060] In FIGS. 7 and 8, alternative delivery devices  200  and  300 , respectively, are illustrated. As described above with respect to the delivery device  100 , delivery devices  200  and  300  each include a catheter device  104  having an outer tube  106  and an inner tube  108 . The delivery device  200  includes a handle assembly  202  and the delivery device  300  includes a handle device  302 , the particular features of which are explained in further detail below.  
     [0061] The handle assembly  202  comprises a first handle portion  204  and a second handle portion  206 . The first handle portion  204  is pivotally attached to the second handle portion  206  at pivot point  208 . Preferably, as shown, the first and second handle portions  204  and  206  lie generally in the same plane. The first handle portion  204  includes a receiver  210  for engaging with the catheter device  104  and which is preferably pivotally attached to the first handle portion  204  at pivot point  212 . The second handle portion  206  includes a sleeve  214  for slideably engaging with the catheter device  104  and which is pivotally attached to the second handle portion  206  at pivot point  216 . As such, the first and second handle portions  204  and  206  may be used to move the inner tube  108  with respect to the outer tube  106  of the catheter assembly  104 , to change the length of the receiving area  110 .  
     [0062] The handle assembly  302  shown in FIG. 8 is similar to the handle assembly  202  shown in FIG. 7 and includes first and second handle portions  304  and  306 . Like the handle assembly  202 , the first handle portion  304  includes a receiver  310  attached thereto at pivot point  312  and the second handle portion includes a sleeve  314  attached thereto at pivot point  316 . Also, the first and second handle portions  304  and  306  are pivotally attached at pivot point  308 . The first and second handle portions  304  and  306  do not lie in the same plane, however. Preferably, the first and second handle portions  304  and  306  are offset with respect to each other. As shown, the first handle portion  304  is generally in the same plane as the catheter device  104  and the second handle portion  306  is offset from the first handle portion  304 . As such, the sleeve  314  is offset with respect to the end of the second handle portion  306  such that it is aligned with the receiver  310 , as illustrated. Alternatively, if desired, the second handle portion  306  may be in the plane of the catheter device  104  and the first handle portion  304  and the receiver  310  may be offset with respect to the second handle portion  306 .  
     [0063] In order to provide the desired movements of the handle portions to deploy a stent from a catheter assembly using handle assemblies of the types described above, it is preferable that each of the assemblies includes at least three pivot points. However, it is understood that actual pivot pins or devices are not necessary, but may instead be replaced by springs or have other configurations that provide the desired degrees of motion for the various components. For example, with a handle assembly like that of assembly  202 , it is contemplated that the pivot point  208  about which two separate handle portions  204  and  206  are pivotally connected may instead include a single piece of material that is bent or curved into a generally V-shaped arrangement. In such an arrangement, the two portions on either side of the V-shaped piece can be squeezed toward each other in such a way that the bottom portion of the V-shaped piece can act as a spring to keep the two portions separated from each other until a force is applied to move the two portions toward each other.  
     [0064] While the catheter assemblies are described above as including two tubes that slide relative to each other to deploy a stent, it is understood that the catheter assemblies may include any arrangement of components that would facilitate the deployment of a stent when the components of a handle assembly are manipulated in any of the manners described. For example, more or less than two tubes may be used, or the tubes may not be concentrically arranged relative to each other. Many other variations of the catheter assembly are contemplated and considered to be within the scope of the present invention.  
     [0065] Finally, FIG. 9 illustrates one preferred embodiment of a delivery system  500  in accordance with the present invention, which generally includes a delivery tool  502  having a catheter assembly  504  inserted into one end of a stent cartridge  506 . This figure illustrates the arrangement of components relative to each other when a stent has been moved from a transfer region of the stent cartridge and loaded into the end of the catheter assembly  504 . At this point, the cartridge  506  may be removed from the catheter assembly  504  and discarded, and the loaded delivery tool  502  may be used to deploy the stent being held within the end of the catheter assembly  504  into a body lumen.  
     [0066] The present invention has now been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is hereby incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein, but only by the structures described by the language of the claims and the equivalents of those structures.