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  Flexible stent and method of manufactureUSPTO Application #: 20060036312Title: Flexible stent and method of manufacture Abstract: A preferred embodiment of a stent provides a folded strut section that provides both structural rigidity and reduction in foreshortening of the stent mechanism. A flexible section provides flexibility for delivery of the stent mechanism. In a second embodiment, flexible section columns are angled with respect to each other, and to the longitudinal axis of the stent. These relatively flexible sections are oppositely phased in order to negate any torsion along their length. In yet another embodiment, the flexible connector can take on an undulating shape (like an “N”), but such that the longitudinal axis of the connector is not parallel with the longitudinal axis of the stent. Finally, a new method is disclosed for making stents. The method consists of performing a standard photochemical machining process of cutting, cleaning and coating the tube with a photoresist. However, unlike former methods, the photoresist image is developed on the surface of the cylindrical metallic tube, which results in a controlled variable etching rate at selected sites on the cylindrical metallic tube during the etching process. Further embodiments provide living hinge connectors and connections along the length of the radial strut member. (end of abstract) Agent: Philip S. Johnson Johnson & Johnson - New Brunswick, NJ, US Inventor: Charles V. Tomonto USPTO Applicaton #: 20060036312 - Class: 623001160 (USPTO) Related Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Arterial Prosthesis (i.e., Blood Vessel), Stent Structure, Having Multiple Connected Bodies The Patent Description & Claims data below is from USPTO Patent Application 20060036312. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from Ser. No. 09/797,815 filed Mar. 2, 2001, now U.S. Pat. No.; which claims priority from Ser. No. 60/272,696, entitled "Flexible Stent and Method of Manufacture", filed Mar. 1, 2001. BACKGROUND ART [0002] A stent is commonly used as a tubular structure left inside the lumen of a duct to relieve an obstruction. Commonly, stents are inserted into the lumen in a non-expanded form and are then expanded autonomously (or with the aid of a second device) in situ. A typical method of expansion occurs through the use of a catheter mounted angioplasty balloon, which is inflated within the stenosed vessel or body passageway, in order to shear and disrupt the obstructions associated with the wall components of the vessel and to obtain an enlarged lumen. [0003] In the absence of a stent, restenosis may occur as a result of elastic recoil of the stenotic lesion. Although a number of stent designs have been reported, these designs have suffered from a number of limitations. These include restrictions on the dimension of the stent. [0004] Other stents are described as longitudinally flexible but consist of a plurality of cylindrical elements connected together. This design has at least one important disadvantage, for example, according to this design, protruding edges occur when the stent is flexed around a curve raising the possibility of inadvertent retention of the stent on plaque deposited on arterial walls. This may cause the stent to form emboli or move out of position and further cause damage to the interior lining of healthy vessels. [0005] Thus, stents are known in the art. Such stents may be expanded during or just after balloon angioplasty. As a general rule, the manufacture of a stent will need to compromise axial flexibility in order to permit expansion and provide overall structural integrity. [0006] Prior stents have had a first end and a second end with an intermediate section between the two ends. The stent further has a longitudinal axis and comprises a plurality of longitudinally disposed bands, wherein each band defines a generally continuous wave along a line segment parallel to the longitudinal axis. A plurality of links maintains the bands in a tubular structure. In a further embodiment of the invention, each longitudinally disposed band of the stent is connected, at a plurality of periodic locations, by a short circumferential link to an adjacent band. The wave associated with each of the bands has approximately the same fundamental spatial frequency in the intermediate section, and the bands are so disposed that the waves associated with them are spatially aligned so as to be generally in phase with one another. The spatial aligned bands are connected, at a plurality of periodic locations, by a short circumferential link to an adjacent band. [0007] In particular, at each one of a first group of common axial positions, there is a circumferential link between each of a first set of adjacent pairs of bands. [0008] At each one of a second group of common axial positions, there is a circumferential link between each of a second set of adjacent rows of bands, wherein, along the longitudinal axis, a common axial position occurs alternately in the first group and in the second group, and the first and second sets are selected so that a given band is linked to a neighboring band at only one of the first and second groups of common axial positions. [0009] Furthermore, this stent can be modified to provide for bifurcated access, whereas the stent itself is uniform throughout. If the manufacturer designs such a stent to have an large enough opening, then it is possible to place the stent such that a pair of stents can be placed one through the other. In this fashion, the stents are capable of being placed at a bifurcation, without any welding or any special attachments. An interlocking mechanism can be incorporated into the stent design to cause the stent to interlock at the desired position during assembly of the device. [0010] Further, a metallic stent has been designed which contains a repeating closed loop feature. The stent is designed such that the closed loop does not change dimensions during expansion. The composite stent is created by filling the area enclosed by the loops with a material that enhances clinical performance of the stent. The material may be a ceramic or a polymer, and may be permanent or absorbable, porous or nonporous and may contain one or more of the following: a therapeutic agent, a radio-opaque dye, a radioactive material, or a material capable of releasing a therapeutic agent, such as rapamycin, cladribine, heparin, nitrous oxide or any other know drugs, either alone or in combination. [0011] It has been seen, however, that it may be desirable to provide for stents that have both flexibility to navigate a tortuous lesion as well as increased column strength to maintain the rigidity necessary after emplacement into the lumen of the body. The preferred designs tend to provide the flexibility via undulating longitudinal connectors. The rigidity is generally provided via the mechanism of slotted tubular stents. It is perceived that there may be mechanisms capable of enhancing the characteristics of these types of stents. Such a stent would be both flexible in delivery and rigid upon emplacement. [0012] Furthermore, it is desirable to be able to produce stents in which the cross-sectional profile of either the struts or the connecting members is tapered (or variable) in size. In addition, it may be desirable to modify stents to have non-rectangular cross-sections. In both these cases, different manufacturing methods may aid in the creation of such stents. SUMMARY OF THE INVENTION [0013] It is an object of the invention to provide a stent having has relatively little foreshortening. [0014] It is an object of the invention to provide a stent having an enhanced degree of flexibility. [0015] It is an object of the invention to provide such a stent while diminishing any compromise in the stent's structural rigidity upon expansion. [0016] It is a further object of the invention to provide a novel method for manufacturing stents. [0017] These and other objects of the invention are described in the following specification. As described herein, a preferred embodiment of a stent provides for a device that contains a flexible section and a folded strut section. The folded strut section opens (like a flower) upon expansion. This folded strut section provides both structural rigidity and reduction in foreshortening of the stent mechanism. The flexible section provides flexibility for delivery of the stent mechanism. [0018] In a second embodiment of the device, there is a columnar section and a flexible section. The columnar section provides for a device that lengthens in the longitudinal direction upon expansion. The flexible section provides for a section that shortens somewhat in the longitudinal direction upon expansion. As a result, there is no shortening or lengthening of the stent during expansion. The flexible section columns are angled, one with respect to the other, and also with respect to the longitudinal axis of the stent, in order to provide flexibility during delivery. This arrangement also to also provide additional resistance to the balloon to prevent "dogboning" of the stent on the balloon during delivery and slippage of the balloon along the stent. These relatively flexible sections are oppositely phased with respect to one another in order to negate any torsion along their length. These flexible sections can further be crimped onto the balloon catheter with a generally smaller profile than prior stent, so that the retention of the stent on the balloon is increased. [0019] In yet another embodiment of the stent of the present invention, the flexible connector can take on an undulating shape (like an "N"), but such that the longitudinal axis of the connector is not parallel with the longitudinal axis of the stent. In this fashion, the flexibility is controlled in a pre-selected axis, which is not the longitudinal axis of the stent. Such an arrangement may be desired, for instance, when one chooses to place a stent in a particularly configured vasculature that has been predetermined by known means, such as intravascular ultrasound ("IVUS.") [0020] In still a further embodiment of the present invention, there are provided "living hinge" connectors, which connect the generally flexible connectors to the stronger radial strut members. These living hinges accomplish a number of the same characteristics found in the prior embodiments disclosed herein. First, because the living hinges tend to expand upon inflation, foreshortening of the length of the stent is further reduced. Second, there is a combined radial strength provided at the intersection between the living hinges and the radial strut members. This creates a small "hoop," which is further resistant to kinking or collapse in situ. Third, as a corollary to the second attribute described above, the living hinge connectors provide for reduced strain along an equivalent length of stent. [0021] In yet another preferred embodiment of the stent of the present invention, the connection point between the radial members and the connector members is moved to a position along the length of a radial strut. Typically, the connection may be placed at a position somewhere midway along the length of the strut. By moving the connection point of the flex connectors closer to the midpoint of the radial ring one can address foreshortening in an controlled fashion. In fact, balloon interaction aside, the connector does not have to stretch to compensate for foreshortening. When the flex connectors are connected at the midpoint of the radial ring, the distance/length through the middle portion of the stent between radial rings will remain unchanged. This is because the midpoint stays relativiely in the same position while the radial arcs of each strut move closer to the midpoint from both sides. By moving the location of the flex connector attachment beyond the mid-point of a strut, to the opposing side, one can actually capitilize on the strut moving closer to the midpoint and thus lengthen the stent upon expansion. Continue reading... Full patent description for Flexible stent and method of manufacture Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Flexible stent and method of manufacture patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Flexible stent and method of manufacture or other areas of interest. ### Previous Patent Application: Stent and process for producing the same Next Patent Application: Apicoaortic conduit connector and method for using Industry Class: Prosthesis (i.e., artificial body members), parts thereof, or aids and accessories therefor ### FreshPatents.com Support Thank you for viewing the Flexible stent and method of manufacture patent info. 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