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  Deformable lumen support devices and methods of useUSPTO Application #: 20080097571Title: Deformable lumen support devices and methods of use Abstract: Lumen support devices and methods of their use are provided. A lumen support includes one or more plastically deformable cells having two stable configurations with no stable configurations between the two stable configurations. The lumen support device may be plastically deformed to other stable configurations. (end of abstract) Agent: Knobbe Martens Olson & Bear LLP - Irvine, CA, US Inventors: Andy E. Denison, Kent C.B. Stalker USPTO Applicaton #: 20080097571 - Class: 623 111 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080097571. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001]This application claims the priority benefit under 35 U.S.C. .sctn.119(e) of the provisional application 60/853,245, filed Oct. 21, 2006 which is hereby incorporated by reference in its entirety. BACKGROUND OF THE INVENTION [0002]1. Field of the Invention [0003]Embodiments described herein relate to lumen supports having plastically deformable structures. [0004]2. Description of Related Technology [0005]Vascular prostheses, commonly referred to as stents, are now widely used in interventional procedures for treating lesions of the coronary arteries and other vessels. Such devices generally have a tubular shape and are deployed in a vessel, and are intended to restore and maintain the patency of a segment of a vessel. Previously-known vascular prostheses are generally either self-expanding or balloon expandable, and may vary in size, shape or other characteristics depending on whether the use is for the cardiac vasculature, carotid arteries, renal arteries, superficial femoral arteries, or other vessels. [0006]Self-expanding and balloon expandable stents often have elasticities associated with a relatively large amount of recoil. As such, the stent may be prone to recoil inward after being expanded to its maximum outer diameter. If this recoil is significant, the stent may not remain stationary relative to the passageway, instead migrating to a point of lesser desirability. As a result, serious or fatal injury to the patient may occur. [0007]Another aspect of stents is the size to which they may be compacted through crimping. Stents may be crimped onto a catheter for delivery to a lesion location within a lumen. One manner of crimping involves the application of a force directed in a radially inward direction to force the stent into a compact profile. However, the stent's diameter may tend to recoil to a diameter greater than its minimum diameter. This recoil typically increases as the material's elasticity increases. One disadvantage of this phenomenon is that, with increased recoil after crimping, the stent's delivery profile is increased, thereby limiting the stent's applicability to small vessels that would otherwise be accessible by a stent with a smaller delivery profile. Another disadvantage is that a stent that is not tightly coupled to the delivery catheter may become dislodged at an undesirable location during delivery. [0008]Different material choices for stents or other medical devices offer different advantages and disadvantages. For example, some highly elastic materials have increased strength and/or increased radiopacity when compared to other materials with a lower elasticity, yet suffer from greater recoil than materials with a lesser elasticity. A balance is desired in which beneficial features of such stent materials may be enjoyed while reducing disadvantages such as recoil. SUMMARY OF THE INVENTION [0009]In view of the foregoing drawbacks of previously-know vascular prostheses and other similar medical devices, one aspect of certain embodiments described herein is to provide a lumen support having one or more unit cells. In particular embodiments, the one or more unit cells are capable of assuming multiple stable configurations. In one aspect of certain embodiments, the lumen support having the one or more multistable unit cells comprises beneficial features of elastic materials. Another aspect of certain embodiments is to provide a lumen support having one or more multistable cells that do not significantly increase in diameter due to recoil following crimping. Yet another object of certain embodiments is to provide a lumen support that does not significantly decrease in diameter due to recoil following expansion. [0010]These and other advantages are achieved by providing a supportive structure having a body comprising a plurality of cells capable of low recoil due to some reversal of elastic strain when crimped. The cells further may undergo plastic deformation as the medical device is deployed into an expanded configuration, and the asymmetrical shape of the cells reduces the degree of recoil in comparison to known stent designs. In certain embodiments, such a supportive structure is well-adapted to be formed of certain elastic materials such as cobalt alloys and stainless steel, thereby being capable of enjoying the advantages of strength and/or radiopacity, with a reduction in effects such as recoil. [0011]In one embodiment, a lumen support is configured to be expanded and contracted to a plurality of stable positions. In some embodiments, the support includes a plurality of cells. In some embodiments, each of the plurality of cells is defined by at least a first segment and a second segment. In some embodiments, the cell includes a first stable collapsed configuration, a second stable collapsed configuration, a first stable expanded configuration, and a second stable expanded configuration. In certain embodiments, the first segment, is made of a material having an elastic range of between about 0.15 to about 1% and an elongation of above 30% and an ultimate tensile strength greater than 500 MPa. As discussed further herein, the strut made of this material exhibits reduced recoil to an applied force. In some embodiments, the second segment is less flexible than the first segment. In certain embodiments, the first segment may transition from a first stable contracted position to a first stable expanded position relative to said second segment. This transition causes the cell to transition from the first stable collapsed configuration to the first stable expanded configuration. In some embodiments, the first segment is configured to plastically deform to a second stable contracted position creating an area for each cell less than the area created when said first segment is at said first stable contracted position. In some embodiments, the first segment is configured to plastically deform to a second stable expanded position creating an area for each cell greater than the area created when said first segment is at said first stable expanded position. In some embodiments, the first segment is configured to transition between contracted and expanded positions through an inversion point in which force is reduced in order to complete the transition. In some embodiments, the first segment has an elastic range of between about 0.3 to about 0.8%. In some embodiments, the first segment substantially conforms to the shape of the second segment in the first stable collapsed configuration. In some embodiments, the second segment comprises a plastically deformable segment made of the material of the first segment. [0012]In another embodiment, a lumen support includes a plastically deformable structure made of a material having an elastic range between about 0.15 to about 1% and an elongation of above 30% and an ultimate tensile strength greater than 500 MPa. Such structure is capable of assuming an original collapsed configuration or a plastically deformed collapsed configuration and an original expanded configuration or a plastically deformed expanded configuration, wherein no stable configurations exist between the original collapsed configurations or the original expanded configuration. In certain embodiments, the structure is defined in part by a first segment and a second segment, the first segment being more flexible than the second segment. In certain embodiments, the first segment is capable of transitioning between a contracted position and an expanded position, relative to the second segment, wherein the first segment passes a transition point between the contracted position and the expanded position that allows force to be decreased during the transition. [0013]In another embodiment, a method of crimping a lumen support on a delivery device is described. Such method may include delivering a lumen support onto a delivery device. Lumen supports are further discussed herein and can be used with any embodiment or feature of any lumen support described herein. The method may further include applying a radially inward force to the lumen support, and deforming one or more unit cells of the lumen support to a plastically deformed collapsed configuration. In certain embodiments, the method may include transitioning the lumen support to a stable collapsed configuration from a stable expanded configuration by application of a force through an inversion point of decreased force. In one embodiment, the lumen support has a smaller diameter in the plastically deformed collapsed configuration than in the stable collapsed configuration. In one embodiment, the lumen support includes a first segment and a second segment, the first segment being more pliable than the second segment. In certain embodiments, the lumen support includes a material having an elastic range between about 0.15 to about 1% and an elongation of above 30% and an ultimate tensile strength greater than 500 MPa. [0014]In another embodiment, a lumen support includes a plurality of unit cells arranged in a first column and a second column, the first and second columns having a tubular shape and being interconnected by at least one flexible connector. In some embodiments, each unit cell in the first column of unit cells is coupled by first flexible articulations. In some embodiments, each unit cell in the second column of unit cells is coupled by second flexible articulations. In some embodiments, at least some of the unit cells of the plurality of unit cells are capable of transitioning between a stable expanded configuration and a stable collapsed configuration by application of a force through an inversion point of decreased force. In some embodiments, the first flexible articulations and the flexible connector are configured to allow one or more unit cells of the first column to conform to a lumen. In certain embodiments, the plurality of unit cells is made of a material having an elastic range between about 0.15 to about 1% and an elongation of above 30% and an ultimate tensile strength greater than 500 MPa. In some embodiments, the material is a cobalt alloy or is stainless steel. [0015]In another embodiment, a balloon catheter includes a balloon and a lumen support device in a crimped configuration coupled to the balloon. In one embodiment, the device includes one or more unit cells capable of transitioning from a stable collapsed configuration to a stable expanded configuration by application of a force through an inversion point of decreased force. In some embodiments, the one or more unit cells are capable of plastically deforming to an expanded plastically deformed configuration. In some embodiments, the lumen support device includes a material having an elastic range between about 0.15 to about 1% and an elongation of above 30% and an ultimate tensile strength greater than 500 MPa. In some embodiments, the material is a cobalt alloy. BRIEF DESCRIPTION OF THE DRAWINGS [0016]The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: [0017]FIG. 1 is a supportive structure in a stable expanded configuration in accordance with one embodiment; [0018]FIG. 2 is a supportive structure in a stable collapsed configuration in accordance with one embodiment; [0019]FIG. 3A is graph comparing the crimp force to the reduction in diameter between a stent constructed in accordance with one embodiment and another stent of a known design; [0020]FIG. 3B is a drawing of various unit cell configurations as correlated to points on the graph of FIG. 3A Continue reading... 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