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Publication numberUS20110184508 A2
Publication typeApplication
Application numberUS 10/443,231
Publication date28 Jul 2011
Filing date21 May 2003
Priority date19 May 1994
Also published asCA2190012A1, CA2190012C, DE69507800D1, DE69507800T2, EP0759730A1, EP0759730B1, US6451052, US6582461, US8221491, US20030208263, WO1995031945A1
Publication number10443231, 443231, US 2011/0184508 A2, US 2011/184508 A2, US 20110184508 A2, US 20110184508A2, US 2011184508 A2, US 2011184508A2, US-A2-20110184508, US-A2-2011184508, US2011/0184508A2, US2011/184508A2, US20110184508 A2, US20110184508A2, US2011184508 A2, US2011184508A2
InventorsPaul Burmeister, Charles Euteneuer, Brian Brown, Paul Fordenbacher, Anthony Vrba
Original AssigneeBoston Scientific Scimed, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Improved tissue supporting devices
US 20110184508 A2
Abstract
A new multiple component stent arrangement which allows for initial self-expansion and subsequent deformation to a final enlarged size.
Images(14)
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Claims(6)
1-34. (canceled)
35. A stent comprising:
a plurality of annular elements extending axially without engaging overlap, each annular element having a compressed state and an expanded state, wherein each annular element has a longitudinal dimension which is smaller in the radially expanded state than in the compressed state; and
at least one connecting member connecting adjacent of said annular elements, the connecting member having a longitudinal dimension and being configured to elongate the longitudinal dimension of the connecting member when the annular elements are transformed from the compressed state to the expanded state.
36. A tissue support device comprising:
a plurality of annular elements, each annular element having a compressed state and a radially expanded state, wherein each annular element has a longitudinal dimension which is smaller in the radially expanded state than in the compressed state; and
connecting members connecting adjacent of said annular elements, the connecting members having a longitudinal dimension and being configured so that the longitudinal dimension of the connecting members elongates longitudinally when the annular elements are transformed from the compressed state to the expanded state to compensate for the smaller longitudinal dimension of the annular elements in the expanded state.
37. A stent as in claim 36 wherein the connectors are U-shaped.
38. A stent as in claim 36 wherein the stent is formed of shape memory metal alloy material.
39-42. (canceled)
Description
    CROSS-REFERENCE TO RELATED APPLICATIONS
  • [0001]
    This application is a Continuation application from Ser. No. 09/427,291, filed on Oct. 26, 1999, which is a Continuation application from Ser. No. 08/737,492 filed on May 18, 1995, as a 371 of PCT/US95/06228 filed May 18, 1995, the contents of which is hereby incorporated by reference, now U.S. Pat. No. 6,582,461, which is a continuation-in-part of application Ser. No. 08/246,320, filed May 19, 1994. This application is also a continuation of application Ser. No. 09/172,590 filed on Oct. 14, 1998, now 6,451,052, which is a Division of application Ser. No. 08/737,492 filed on May 18, 1995, as a 371 of PCT/US95/06228 filed May 18, 1995, now U.S. Pat. No. 6,582,461, which is a continuation-in-part of application Ser. No. 08/246,320, filed May 19, 1994.
  • BACKGROUND OF THE INVENTION
  • [0002]
    This invention relates to tissue supporting devices in general and most particularly to vascular stents for placement in blood vessels. A primary feature of the devices of this invention is that they are expandable within the body.
  • [0003]
    In the past, such devices have been provided for implantation within body passageways. These devices have been characterized by the ability to be enlarged radially, often having been introduced into the desired position in the body as by percutaneous techniques or surgical techniques.
  • [0004]
    These devices are either expanded mechanically, such as by expansion of a balloon positioned inside the device, or are capable of releasing stored energy to self-expand themselves within the body.
  • [0005]
    The materials which have been used to make up these devices have included ordinary metals, shape memory alloys, various plastics, both biodegradable and not, and the like.
  • [0006]
    This invention is concerned with the use of these materials in a new multiple component arrangement which allows for initial self-expansion and subsequent deformation to a final enlarged diameter in the body.
  • [0007]
    Balloon expandable stents do not always expand uniformly around their circumference. As a result, healing may not take place in a consistent manner. If the stent is coated or covered, non-uniform expansion may tear the covering or coating. Additionally, long stents of this type may require long balloons which can be difficult to handle, difficult to size, and may not offer ideal performance in tortuous passages in blood vessels and the like.
  • [0008]
    Thus, when addressing such issues, self-expandable stents have been thought to be generally more desirable. Unfortunately, one cannot control the degree of expansion and hence the degree of embedment in the vessel wall. It has been determined that a stent must be embedded to some degree to be clinically satisfactory.
  • [0009]
    The stents of the present invention provide the best features of both of these types of stents without their drawbacks.
  • SUMMARY OF THE INVENTION
  • [0010]
    The tissue supporting devices of this invention are generally cylindrical or tubular in overall shape and of such a configuration as to allow radial expansion for enlargement. They are often referred to herein in the general sense as “stents”. Furthermore, the devices are comprised of at least one component, element, constituent or portion which exhibits a tendency to self-expand the device to an expanded size and at least one other component, element, constituent or portion which is deformable so as to allow an external force, such as a balloon positioned within the body of the device, to further expand it to a final, larger desired expanded size. The terms “component”, “telement”, “constituent” and “portion” are often referred to herein collectively as “portion”.
  • [0011]
    Preferably, the devices of the invention are made of metal and most preferably of shape memory alloys.
  • [0012]
    In one embodiment, a first portion is a resilient spring-like metal for self-expansion and a second portion is a deformable metal for final sizing. In a more preferred shape memory embodiment, a first portion is a self-expanding austenitic one and a second is a martensitic one capable of deformation. In the case of shape memory embodiments the “portions” may be discrete or merely different phases of an alloy.
  • [0013]
    The most preferred embodiment of the invention is a stent, preferably of shape memory alloy. The most preferred shape memory alloy is Ni—Ti, although any of the other known shape memory alloys may be used as well. Such other alloys include: Au—Cd, Cu—Zn, In—Ti, Cu—Zn—Al, Ti—Nb, Au—Cu—Zn, Cu—Zn—Sn, Cu—Zn—Si, Cu—Al—Ni, Ag—Cd, Cu—Sn, Cu—Zn—Ga, Ni—Al, Fe—Pt, U—Nb, Ti—Pd—Ni, Fe—Mn—Si, and the like. These alloys may also be doped with small amounts of other elements for various property modifications as may be desired and as is known in the art.
  • [0014]
    The invention will be specifically described hereinbelow with reference to stents, a preferred embodiment of the invention although it is broadly applicable to tissue support devices in general.
  • BRIEF DESCRIPTION OF THE FIGURES
  • [0015]
    FIG. 1 is a braided stent according to one embodiment of this invention.
  • [0016]
    FIG. 2 is a graph showing the martensitic/austenitic temperature transformation curve and the superelastic area of a shape memory alloy.
  • [0017]
    FIG. 3 is an end view of a layered stent having two discrete components according to one aspect of this invention.
  • [0018]
    FIGS. 4 a and 4 b are graphs showing the martensitic/austenitic temperature transformation curves of the layers in the stent of FIG. 3.
  • [0019]
    FIGS. 5 a and 5 b are views of another embodiment of the invention comprised of alternating rings of shape memory alloy.
  • [0020]
    FIG. 6 is a showing of a stent fragment of a braided version of a shape memory stent of this invention.
  • [0021]
    FIG. 7 is a graph showing a temperature window for a shape memory alloy to be used in yet another stent version of this invention.
  • [0022]
    FIG. 7 a is a graph showing expansion of a stent with temperature.
  • [0023]
    FIG. 7 b is a graph of the same type, the stent having been cold-worked.
  • [0024]
    FIG. 7 c is a graph of the same type, the stent having had pseudoelastic prestraining.
  • [0025]
    FIG. 7 d is a graph of the same type, the stent having amnesia inducement.
  • [0026]
    FIGS. 8-11 show various expandable configurations (closed and open) illustrated in fragment which may be used in the stents of this invention. FIGS. 9 a and 9 b show a preferred embodiment of an articulated stent.
  • [0027]
    FIG. 12 shows another version of an expandable stent of the invention.
  • [0028]
    FIG. 13 shows yet another version of a stent which may be used with the invention.
  • [0029]
    FIG. 14 is a schematic showing of a braided stent made up of a plurality of strands.
  • [0030]
    FIG. 15 is a detail of a single strand from the stent of FIG. 14 showing that the strand is made up of a plurality of wires of two different types.
  • [0031]
    FIG. 16 is a cross-sectional view taken along line 16-16 of FIG. 15 showing the two different types of wire.
  • DETAILED DESCRIPTION OF THE INVENTION
  • [0032]
    Preferred embodiments of this invention are described below with particular reference to the accompanying drawing Figures.
  • [0033]
    Referring first to the embodiment shown in FIG. 1, a stent 10 is shown comprised of braided or interwoven metal strands 12 and 14. Strands 12 are of a resilient spring-like metal such as spring steel, Elgiloy for example. Preferably, strands 12 are spirally extending in the same direction, spiraling to the right as seen in FIG. 1. Strands 14 are of a deformable or annealed metal such as stainless steel and are preferably spiraled in the opposite direction as strands 12, as shown in FIG. 1.
  • [0034]
    Given such a stent construction of two components i.e., strands 12 and. 14, it can be seen that stent 10 may be readily loaded on a catheter as by placing it over an uninflated balloon on a balloon catheter and compressing it tightly around the balloon and then placing a sheath over the stent to hold it in place during the transluminal placement procedure. Once in place, the sheath is removed, for example slid back, to expose the stent, allowing it to self-expand by force of the resilient strands 12 to substantially assume a self-expanded shape/size. Some self-expansion may be restrained if held back by strands 14. To finally adjust the size of the stent, the balloon may be expanded by inflation from within the stent to exert an outward radial force on the stent and further enlarge it by stretching and deforming the deformable metal of strands 14. This may be aided by building into strands 14, a series of readily deformable structures or means such as bends or kinks 16 as shown in FIG. 1. It can be seen that a permanent adjustable size beyond the self-expanded size may be obtained with this embodiment. It is to be noted that many configurations other than braided may be readily devised to take advantage of this two component concept, including various of the subsequent configurations-described hereinbelow. Also, it should be noted that, although not preferred, the stent may be initially deployed without a balloon; the balloon following on a separate catheter.
  • [0035]
    Referring now to subsequent features, other preferred embodiments of the invention will be described which make use of shape memory alloys and some of their unique properties, primarily their special types of deformation i.e., shape memory deformation in martensite and/or superelastic deformation in austenite.
  • [0036]
    The term “superelasticity” is used to describe the property of certain shape memory alloys to return to their original shape upon unloading after a substantially deformation while in their austenitic state. Superelastic alloys can be strained while in their austenitic state more than ordinary spring materials without being plastically deformed. This unusually large elasticity in the austenitic state is also called “pseudoelasticity”, because the mechanism is nonconventional in nature, or is also sometimes referred to as “transformational superelasticity” because it is caused by a stress induced phase transformation. Alloys that show superelasticity also undergo a thermoelastic martensitic transformation which is also the prerequisite for the shape memory effect. Superelasticity and shape memory effects are therefore closely related. Superelasticity can even be considered part of the shape memory effect.
  • [0037]
    The shape memory and superelasticity effects are particularly pronounced in Ni—Ti alloys. This application will therefore focus on these alloys as the preferred shape memory alloys. The shape memory effect in Ni—Ti alloys has been described many times and is well known.
  • [0038]
    In near-equiatomic Ni—Ti alloys, martensite forms on cooling from the body centered cubic high temperature phase, termed austenite, by a shear type of process. This martensitic phase is heavily twinned. In the absence of any externally applied force transformation takes place with almost no external macroscopic shape change. The martensite can be easily deformed by a “flipping over” type of shear until a single orientation is achieved. This process is also called “detwinning”.
  • [0039]
    If a deformed martensite is now heated, it reverts to austenite. The crystallographic restrictions are such that it transforms back to the initial orientation thereby restoring the original shape. Thus, if a straight piece of wire in the austenitic condition is cooled to form martensite it remains straight. If it is now deformed by bending, the twinned martensite is converted to deformed martensite. On heating, the transformation back to austenite occurs and the bent wire becomes straight again. This process illustrates the shape memory deformation referred to above.
  • [0040]
    The transformation from austenite to martensite and the reverse transformation from martensite to austenite do not take place at the same temperature. A plot of the volume fraction of austenite as a function of temperature provides a curve of the type shown schematically in FIG. 2. The complete transformation cycle is characterized by the following temperatures: austenite start temperature (As), austenite finish temperature (Af), both of which are involved in the first part (1) of an increasing temperature cycle and martensite start temperature (Ms) and martensite finish temperature (Mf), both of which are involved in the second part (2) of a decreasing temperature cycle.
  • [0041]
    FIG. 2 represents the transformation cycle without applied stress. However, if a stress is applied in the temperature range between As and Md, martensite can be stress-induced. Stress induced martensite is deformed by detwinning as described above. Less energy is needed to stress induce and deform martensite than to deform the austenite by conventional mechanisms. Up to about 8% strain can be accommodated by this process (single crystals of specific alloys can show as much as about 25% pseudoelastic strain in certain directions). As austenite is the thermodynamically stable phase at temperatures between As and Md under no-load conditions, the material springs back into its original shape when the stress is no longer applied.
  • [0042]
    It becomes increasingly difficult to stress-induce martensite at increasing temperatures above Af. Eventually, it is easier to deform the material by conventional mechanisms (movement of the dislocation, slip) than by inducing and deforming martensite. The temperature at which martensite can no longer be stress-induced is called Md. Above Md, Ni—Ti alloys are deformed like ordinary materials by slipping.
  • [0043]
    Additional information regarding shape memory alloys is found in the following references, all of which are incorporated fully herein by reference:
    • Super Elastic Nickel-Titanium Wires” by Dieter Stockel and Weikang Yu of Raychem Corporation, Menlo Park, Calif., copy received November 1992;
    • Metals Handbook, Tenth Edition, Vol. 2, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, “Shape Memory Alloys” by Hodgson, Wu and Biermann, pp. 897-902; and,
    • In Press, Titanium Handbook, ASM (1994), Section entitled “Structure and Properties of Ti—Ni Alloys by T. W. Duerig and A. R. Pelton.
  • [0047]
    Since the most preferred shape memory alloy is Ni—Ti, the martensitic state of this alloy may be used to advantage in the two component concept of this invention.
  • [0048]
    For example, with reference to FIG. 3, a layered construction may be provided in a stent 30 (shown in end view) which is generally a hollow cylindrical or tubular body in shape but which may be formed in a wide variety of specific configurations or patterns to foster radial expansion of the body as exemplified in FIGS. 1, 5, 6 and in subsequent FIGS. 8-11.
  • [0049]
    Stent 30 is comprised of at least two layers 32 and 34, one of which 32 is a Ni—Ti alloy (50.8 atomic wt. % Ni, balance Ti, transition temperature of Af=0 C.) and normally in the austenitic state, the other of which 34 is a Ni—Ti (49.4 atomic wt. % Ni, balance Ti, transition temperature Af=60 C.) and normally in the martensitic state. Preferably, the inner layer is 32 and the outer layer is 34. However, this may be reversed and also a plurality of layers, alternating or otherwise, may be utilized in this particular embodiment.
  • [0050]
    Stent 30 is made to a fabricated size and shape (parent shape) which provides austenitic layer 32 its parent shape and size i.e., its superelastic high temperature shape and size. Obviously, in its as fabricated condition, the Ni—Ti alloy of austenitic layer 32 is selected so as to have a transition temperature range between its austenitic and martensitic states which is lower than body temperature as to ensure that in the body and at body temperatures the austenitic state will always prevail.
  • [0051]
    On the other hand, martensitic layer 34 is of a Ni—Ti alloy having a transition temperature range significantly greater than body temperature so as to ensure that under body conditions the martensitic state will always prevail and the alloy will never transform to austenite in stent use. This is shown in the graphs of FIGS. 4 a and 4 b which demonstrate the relative transition temperatures of layers 32 and 34, respectively for purposes of this invention. It can be seen from these graphs that the normal condition of layer 32 (FIG. 4 a) at body temperatures and higher is the austenitic state while the normal condition of layer 34 (FIG. 4 b) at body temperatures is martensitic.
  • [0052]
    To manufacture the layered construction, one may make the austenitic portion with any standard metallurgical technique and vapor deposit the martensitic portion on its surface. Other manufacturing techniques such as diffusion bonding, welding, ion beam deposition, and various others will be apparent to those familiar with this art.
  • [0053]
    Such a stent may be compressed or constrained (deformed to a small diameter) onto a balloon catheter as described for the previous embodiment and captured within a sheath. During the constrainment, austenitic layer 32 may stress induce to a martensitic state. In the alternative, the stent may be cooled below the transition temperature of layer 32 to facilitate its deformation and constrainment. Martensitic layer 34 merely undergoes deformation. Thus the stent may be “loaded” onto a balloon catheter. However, with temperature changes occurring up to body temperature, layer 32 will remain martensite until the constraint is removed. When released in place in the body, stent 30 will expand to a percentage of its self-expanded size and shape due to the transformation of layer 32 from martensite to austenite at which point the balloon may be used to radially expand the stent to a greater permanent diameter by deforming martensitic layer 34. On the other hand, initial deployment can take place without a balloon which may be separately inserted after deployment.
  • [0054]
    The two component concept of the invention in the layered embodiment of FIG. 3 requires both the martensitic and austenitic phase characteristics of shape memory alloy(s) in the two discrete components 32 and 34.
  • [0055]
    Preferably, the stent is fabricated in such a way that the austenitic layer 32 tends to self-expand stent 30 to a predetermined fabricated diameter (parent shape, also referred to herein as “shape memorized diameter”). The martensitic layer 34 tends to hold back this self-expansion, preventing full expansion. For example, the stent may only be able to self-expand to 75% of its full possible diameter (as determined by the austenitic layer). Therefore, expansion beyond 75% is accomplished by an applied external force, as by the balloon inside the stent. It is suggested that the stent not be expanded beyond its normal fabricated diameter for the austenitic layer 32 will have the tendency of making the stent diameter smaller as it tries to recover its fabricated diameter (parent shape). If the stent is subjected to a temperature above body temperature and above the transition temperature of the martensitic layer (which is clinically unlikely), the stent will self-expand to the fabricated diameter only. Depending on design size there are thus provided permanent stents capable of fulfilling any needed range of sizes with an adjustable sizing capability.
  • [0056]
    As is known in the art, the desired properties of the shape memory alloys required for use in this invention may be obtained by alloy composition and working and heat treatment of the alloys, in various combinations or singly.
  • [0057]
    Manufacturing techniques influence the phase characteristics of the material. Alloy composition, work history, and heat treatment all influence the final characteristics. At a specific operating temperature, say body temperature, the austenite phase material will have a transition temperature below body temperature (i.e., Af=0 C.). The material is capable of taking high strains and recovering after the load is released. The martensite phase material will have a higher transition temperature than body temperature (i.e., Af=60 C.), and is characteristically soft and pliable and retains the deformed shape after load removal. This martensite deformation is caused by detwinning, not the typical plastic deformation, or yielding, of crystal slip.
  • [0058]
    With reference to FIGS. 5 and 6, other stent constructions are shown which are similar to the layered version of FIG. 3 in so far as utilization of the two component concept of this invention is concerned.
  • [0059]
    FIGS. 5 a and 5 b shows a stent 50 made up of alternating expandable rings 52 and 54 of austenitic and martensitic alloys, respectively, analogous to layers 32 and 34 of the FIG. 3 embodiment. Rings 52 and 54 for example are interconnected by strut members 56 which may be of any material capable of rigidly holding the rings together. Other interconnector means may be used. As can be seen in FIG. 5 b, the placement of strut members 56 does not require them to take part in the radial expansion of the stent and they can therefore be of a relatively ordinary material such as stainless steel.
  • [0060]
    Referring now to FIG. 6, a braided or interwoven construction is shown similar in construction to that of the embodiment of FIG. 1. In this embodiment, strands 62 extending to the right in FIG. 6 are an alloy in the austenitic state whereas strands 64 extending to the left in FIG. 6 are an alloy in the martensitic state.
  • [0061]
    Referring now to the graph of FIG. 7, it is demonstrated that the two component concept of the invention may be embodied in two phases, i.e., components of a single shape memory alloy and need not be in the form of two discrete components such as layers, members, wires, etc. In the graph of FIG. 7, it can be seen that an alloy composition can be selected such that it has a phase transition temperature window that bounds the proposed operating temperatures of the stent, such as the normal body temperature range. Within this transitional window or zone, the material undergoes the phase transition and is effectively compositionally comprised of a ratio of austenitic to martensitic phase depending on the temperature of the stent. This ratio should be selected so as to provide sufficient radial force from the austenite phase while still allowing for further expansion of the martensite phase with a mechanical expansion means such as a balloon. Selecting body temperature as the operating temperature, a Ni—Ti alloy of about 50/50 atomic wt. % composition (range about 49/51%) will provide an acceptable “window” for this embodiment, the two components are the austenite and martensite phases of the nitinol.
  • [0062]
    The method of making a stent may be described as follows. Age the shape memory material (Ni Ti) until body temperature falls somewhere within the transformation window. Therefore the stent will not fully recover to its high temperature shape at body temperature. An example of this technique is described below.
  • [0063]
    A stent of tubular 50.8% Ni balance Ti was prepared having a 1.5 mm diameter. It was substantially all austenite at room temperature, the Af being about 15-20 C. and therefore being superelastic at room temperature. The stent was cooled to below room temperature to form substantially all martensite and mechanically expanded to 4.7 mm in diameter. It was maintained at the 4.7 mm in diameter and heat treated at 500 C. for 30 minutes and water quenched. Finally, it was again cooled to below room temperature to form substantially all martensite and compressed to a diameter of 1.5 mm. After deployment and at body temperature the stent has a diameter of 3.5 mm. At about 70% of full expansion, i.e., about 40 C. it had a diameter of 4.5 mm and at 42 C. it had a fully expanded diameter of 4.7 mm.
  • [0064]
    This method works fairly well, but due to the slope of the temperature versus diameter plot being extremely vertical at body temperature, a small change in body temperature, or manufacturing control, can have a large impact on the actual self expansion diameter. As can be seen from FIG. 7, the slope of the line between Af and As is rather steep with small changes in temperature leading to large changes in percent austenite and consequently large changes in diameter of a stent made of such an alloy. FIG. 7 a shows a temperature versus diameter plot. Three methods of modifying the slope of the line on the temperature versus diameter graph are cold work, pseudoelastic prestraining, and amnesia inducement, illustrated in FIGS. 7 b, 7 c and 7 d, respectively.
  • [0000]
    Cold Work
  • [0065]
    Residual cold work in nitinol draws out or masks the point of Af on the diameter versus the temperature curve. This is seen by the sluggish increase in diameter as temperature increases in the last 20-30% of recover. By utilizing the effects of cold work, the effects of temperature change on diameter can be reduced in the last 20 to 30% of stent expansion. Shown in FIG. 7 b is an example of a temperature versus diameter plot for a cold worked part. FIG. 7 a above shows an example of a part without cold work.
  • [0000]
    Pseudoelastic Prestraining
  • [0066]
    Utilizing the effects of pseudoelastic prestraining (S. Eucken and T. W. Duerig, ACTA Metal, Vol. 37, No. 8, pp 2245-2252, 1989) one can create two distinct plateaus in the stress-strain behavior. This difference in stress strain behaviors can be directly linked to two distinct Af temperatures for the two plateaus. By placing the transition between the two plateaus at the transition from self expanding to balloon expanding, i.e., 70%, one can control the characteristics of the stent at body temperature. The goal would be to place the Af temperature for the first plateau (from maximum compression to 70% expansion) below body temperature such that the stent has self expanding characteristics. The Af temperature for the second plateau would be above body temperature such that there is no additional self expansion in this region (70 to 100% expansion) a mechanical device, like a balloon, can then be used to custom size the stent between 70% and 100% of the high temperature shape. Results of such a technique is shown in FIG. 7 c.
  • [0000]
    Amnesia Inducement
  • [0067]
    One of the characteristics of nitinol is cycle amnesia. This was also discussed about in the article referred to immediately above. As nitinol is cycled from its heat set shape as shown in FIG. 7 d, there is an increase in the amount of amnesia to recover to the heat set shape with each cycle. As long as this amnesia is not caused by permanent plastic deformation, the amnesia can be removed by heating the part above Md. This shows there is martensite left in the part after cycling which is preventing full recovery in the austenite phase (just above Af). This presence of non recoverable martensite (below Md) is what may be used for the balloon expansion region of the stent.
  • [0068]
    FIGS. 8-11 represent examples of various expandable configurations (a=closed, b=expanded) which may be incorporated into the devices of this invention. The version shown in FIGS. 10 a and 10 b may be modified as shown in FIGS. 10 c and 10 d (closed and open, respectively) by omitting portions (indicated at 100 in FIGS. 10 c and 10 d) as to render the stent flexible for articulation. This may be done to other of the structures as well to improve flexibility.
  • [0069]
    Yet another version of a device incorporating the two component concept of the invention is shown in FIG. 12. In this embodiment, a fragment of a stent 110 is shown. The stent includes a self-expanding component 112 and a deformable, external force expandable component 114. Self expanding component 112 may be resilient spring-like metal such a stainless steel or it may preferably be a shape memory alloy in the austenitic state. Component 114 may be any deformable metal or the like such as annealed stainless steel or preferably a shape memory alloy in the martensitic state. The two components may simply be mechanically, welded or bonded together. Functions and operations are as described hereinabove.
  • [0070]
    Referring to FIG. 13 a version analogous to the embodiment of FIG. 12 is shown in which the two component concept is again embodied as different zones or portions of a single metal material.
  • [0071]
    As shown in FIG. 13, a stent 120 (fragment showing) is of a self-expanding component 122 and a deformable component 124, both of which may be a single metal as spring steel or austenitic Ni—Ti which has been appropriately treated with respect to component 124 as by localized heat treatment or the like to alter the characteristics of the material of the 122 component so as to render it deformable or martensitic, depending on whether it is merely resilient or is austenitic. Again, function and operation are the same as with other embodiments.
  • [0072]
    Referring now to FIGS. 14-16, a multi-strand braided stent is shown in FIG. 15. Each strand 150 in the stent is a micro-cable. That is, each strand is made up of a plurality of wires 152 and 154 as is seen in FIGS. 15 and 16. Each of the wires 152 and 154 consists of two different nitinol alloys as seen best in FIG. 16, or one nitinol and one ordinary metal such as stainless steel, platinum or tantalum. The latter two would provide enhanced radiopacity. One nitinol alloy wire 154 has an austenitic finish (Af) temperature less than body temperature. The other wire 152 could be nitinol having an As (austenitic start) greater than body temperature. Also, it could be an ordinary metal. Additionally, one or more of the strands may be of a biodegradable material such as a plastic or may be of a material including an absorbable drug.
  • [0073]
    Since the two alloys are stranded into micro-cable one does not have to engage in selective, discrete heat treating methods to produce both shape memory and martensitic effects.
  • [0074]
    Radiopaque portions or coatings may be included on any parts of these stents as is known in the prior art.
  • [0075]
    While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.
  • [0076]
    The above Examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3174851 *1 Dec 196123 Mar 1965Buehler William JNickel-base alloys
US3585647 *25 Apr 196822 Jun 1971Baxter Laboratories IncAntithrombogenic article and process
US3657744 *8 May 197025 Apr 1972Univ MinnesotaMethod for fixing prosthetic implants in a living body
US3808113 *30 Jul 197130 Apr 1974Zaidan Hojin Seisan Kaihatsu KMethod for manufacturing medical articles composed of various synthetic high polymers coated with collagen and exposed to radiation
US3868956 *5 Jun 19724 Mar 1975Ralph J AlfidiVessel implantable appliance and method of implanting it
US4030503 *5 Nov 197521 Jun 1977Clark Iii William TEmbolectomy catheter
US4140126 *18 Feb 197720 Feb 1979Choudhury M HasanMethod for performing aneurysm repair
US4149911 *17 Jan 197817 Apr 1979Raychem LimitedMemory metal article
US4244140 *14 Nov 197713 Jan 1981Kibong KimToys with shape memory alloys
US4313231 *30 Oct 19802 Feb 1982Kabushiki Kaisha Tatebe SeishudoVascular prosthesis
US4319363 *23 May 197916 Mar 1982Vettivetpillai KetharanathanVascular prostheses
US4326532 *6 Oct 198027 Apr 1982Minnesota Mining And Manufacturing CompanyAntithrombogenic articles
US4425908 *22 Oct 198117 Jan 1984Beth Israel HospitalBlood clot filter
US4435853 *30 Apr 198213 Mar 1984Hansa Medical Products, Inc.Voice prosthesis device and placement tool therefor
US4503569 *3 Mar 198312 Mar 1985Dotter Charles TTransluminally placed expandable graft prosthesis
US4509517 *30 Sep 19829 Apr 1985Zibelin Henry SKidney stone instrument
US4512338 *25 Jan 198323 Apr 1985Balko Alexander BProcess for restoring patency to body vessels
US4572186 *7 Dec 198325 Feb 1986Cordis CorporationVessel dilation
US4577631 *16 Nov 198425 Mar 1986Kreamer Jeffry WAneurysm repair apparatus and method
US4580568 *1 Oct 19848 Apr 1986Cook, IncorporatedPercutaneous endovascular stent and method for insertion thereof
US4649922 *23 Jan 198617 Mar 1987Wiktor Donimik MCatheter arrangement having a variable diameter tip and spring prosthesis
US4655771 *11 Apr 19837 Apr 1987Shepherd Patents S.A.Prosthesis comprising an expansible or contractile tubular body
US4665906 *21 May 198619 May 1987Raychem CorporationMedical devices incorporating sim alloy elements
US4665918 *6 Jan 198619 May 1987Garza Gilbert AProsthesis system and method
US4681110 *2 Dec 198521 Jul 1987Wiktor Dominik MCatheter arrangement having a blood vessel liner, and method of using it
US4728322 *5 Feb 19861 Mar 1988Menlo Care, Inc.Adjustable catheter assembly
US4729766 *22 Apr 19858 Mar 1988Astra Meditec AktiebolagVascular prosthesis and method in producing it
US4732152 *5 Dec 198522 Mar 1988Medinvent S.A.Device for implantation and a method of implantation in a vessel using such device
US4733665 *7 Nov 198529 Mar 1988Expandable Grafts PartnershipExpandable intraluminal graft, and method and apparatus for implanting an expandable intraluminal graft
US4739762 *3 Nov 198626 Apr 1988Expandable Grafts PartnershipExpandable intraluminal graft, and method and apparatus for implanting an expandable intraluminal graft
US4740207 *10 Sep 198626 Apr 1988Kreamer Jeffry WIntralumenal graft
US4795458 *2 Jul 19873 Jan 1989Regan Barrie FStent for use following balloon angioplasty
US4800882 *13 Mar 198731 Jan 1989Cook IncorporatedEndovascular stent and delivery system
US4817600 *22 May 19874 Apr 1989Medi-Tech, Inc.Implantable filter
US4820298 *20 Nov 198711 Apr 1989Leveen Eric GInternal vascular prosthesis
US4822361 *24 Dec 198618 Apr 1989Sumitomo Electric Industries, Ltd.Tubular prosthesis having a composite structure
US4830003 *17 Jun 198816 May 1989Wolff Rodney GCompressive stent and delivery system
US4831094 *3 Nov 198716 May 1989Societe Chimique Des Charbonnages, S.A.Articles having shape recovering properties and a method for using it
US4832055 *8 Jul 198823 May 1989Palestrant Aubrey MMechanically locking blood clot filter
US4848343 *30 Oct 198718 Jul 1989Medinvent S.A.Device for transluminal implantation
US4893623 *20 Nov 198716 Jan 1990Advanced Surgical Intervention, Inc.Method and apparatus for treating hypertrophy of the prostate gland
US4911713 *27 Jan 198727 Mar 1990Sauvage Lester RMethod of making vascular prosthesis by perfusion
US4911716 *12 Apr 198927 Mar 1990Hansa Medical Products, Inc.Surgical implant for a voice prosthesis
US4913141 *25 Oct 19883 Apr 1990Cordis CorporationApparatus and method for placement of a stent within a subject vessel
US4921484 *25 Jul 19881 May 1990Cordis CorporationMesh balloon catheter device
US4921499 *5 Oct 19881 May 1990Ordev B.V.Adjustable prosthesis
US4922905 *28 May 19878 May 1990Strecker Ernst PDilatation catheter
US4926860 *5 Feb 198822 May 1990Flexmedics CorporationARthroscopic instrumentation and method
US4934380 *23 Nov 198819 Jun 1990Boston Scientific CorporationMedical guidewire
US4990155 *19 May 19895 Feb 1991Wilkoff Howard MSurgical stent method and apparatus
US4994069 *2 Nov 198819 Feb 1991Target TherapeuticsVaso-occlusion coil and method
US4994071 *22 May 198919 Feb 1991Cordis CorporationBifurcating stent apparatus and method
US4998923 *23 Dec 198812 Mar 1991Advanced Cardiovascular Systems, Inc.Steerable dilatation catheter
US5003989 *10 Jul 19902 Apr 1991Advanced Cardiovascular Systems, Inc.Steerable dilation catheter
US5019090 *1 Sep 198828 May 1991Corvita CorporationRadially expandable endoprosthesis and the like
US5035712 *12 Jun 199030 Jul 1991Ordev B.V.Self-adjusting prosthesis attachment
US5078726 *9 Apr 19907 Jan 1992Kreamer Jeffry WGraft stent and method of repairing blood vessels
US5078736 *4 May 19907 Jan 1992Interventional Thermodynamics, Inc.Method and apparatus for maintaining patency in the body passages
US5100429 *20 Oct 198931 Mar 1992C. R. Bard, Inc.Endovascular stent and delivery system
US5102417 *28 Mar 19887 Apr 1992Expandable Grafts PartnershipExpandable intraluminal graft, and method and apparatus for implanting an expandable intraluminal graft
US5104404 *20 Jun 199114 Apr 1992Medtronic, Inc.Articulated stent
US5108420 *1 Feb 199128 Apr 1992Temple UniversityAperture occlusion device
US5123917 *27 Apr 199023 Jun 1992Lee Peter YExpandable intraluminal vascular graft
US5129883 *26 Jul 199114 Jul 1992Michael BlackCatheter
US5176664 *9 Oct 19905 Jan 1993Kenneth WeismanFemale voiding assist device and method
US5183085 *27 Sep 19912 Feb 1993Hans TimmermansMethod and apparatus for compressing a stent prior to insertion
US5189110 *16 Sep 199123 Feb 1993Asahi Kasei Kogyo Kabushiki KaishaShape memory polymer resin, composition and the shape memorizing molded product thereof
US5190546 *9 Apr 19912 Mar 1993Raychem CorporationMedical devices incorporating SIM alloy elements
US5195984 *19 Feb 199123 Mar 1993Expandable Grafts PartnershipExpandable intraluminal graft
US5197978 *26 Apr 199130 Mar 1993Advanced Coronary Technology, Inc.Removable heat-recoverable tissue supporting device
US5201901 *7 Oct 198813 Apr 1993Terumo Kabushiki KaishaExpansion unit and apparatus for expanding tubular organ lumen
US5211658 *5 Nov 199118 May 1993New England Deaconess Hospital CorporationMethod and device for performing endovascular repair of aneurysms
US5217483 *15 May 19928 Jun 1993Numed, Inc.Intravascular radially expandable stent
US5275622 *13 Jul 19904 Jan 1994Harrison Medical Technologies, Inc.Endovascular grafting apparatus, system and method and devices for use therewith
US5282824 *15 Jun 19921 Feb 1994Cook, IncorporatedPercutaneous stent assembly
US5292331 *24 Aug 19898 Mar 1994Applied Vascular Engineering, Inc.Endovascular support device
US5304200 *13 Jan 199319 Apr 1994Cordis CorporationWelded radially expandable endoprosthesis and the like
US5314472 *1 Oct 199124 May 1994Cook IncorporatedVascular stent
US5383892 *6 Nov 199224 Jan 1995Meadox FranceStent for transluminal implantation
US5601593 *18 Aug 199511 Feb 1997Willy Rusch AgStent for placement in a body tube
US5609605 *4 May 199511 Mar 1997Ethicon, Inc.Combination arterial stent
US5707387 *25 Mar 199613 Jan 1998Wijay; BandulaFlexible stent
US5733303 *31 May 199531 Mar 1998Medinol Ltd.Flexible expandable stent
US5735871 *6 Dec 19957 Apr 1998Sgro; Jean-ClaudeSelf-expanding endoprosthesis
US5749825 *18 Sep 199612 May 1998Isostent, Inc.Means method for treatment of stenosed arterial bifurcations
US5755772 *26 Apr 199626 May 1998Medtronic, Inc.Radially expansible vascular prosthesis having reversible and other locking structures
US5879370 *28 May 19979 Mar 1999Fischell; Robert E.Stent having a multiplicity of undulating longitudinals
US5888201 *13 Jun 199730 Mar 1999Schneider (Usa) IncTitanium alloy self-expanding stent
US5913895 *2 Jun 199722 Jun 1999Isostent, Inc.Intravascular stent with enhanced rigidity strut members
US5916234 *21 Jul 199729 Jun 1999Advanced Cardiovascular Systems, Inc.Expandable stents and method for making same
US6051021 *26 May 199818 Apr 2000Medicorp, S.A.Self-expanding endoprosthesis
US6183508 *12 Nov 19986 Feb 2001Schneider IncMethod for treating a vessel with a titanium alloy stent
US6245100 *1 Feb 200012 Jun 2001Cordis CorporationMethod for making a self-expanding stent-graft
US6251134 *28 Feb 199926 Jun 2001Inflow Dynamics Inc.Stent with high longitudinal flexibility
US6348065 *24 Jul 199819 Feb 2002Scimed Life Systems, Inc.Longitudinally flexible expandable stent
US6517547 *11 Aug 200011 Feb 2003Angiomed Gmbh & Co. Medizintechnik KgStent delivery system
US6562063 *30 Nov 199913 May 2003Scimed Life Systems, Inc.Stent delivery apparatus and method
US6562067 *8 Jun 200113 May 2003Cordis CorporationStent with interlocking elements
US20070150049 *15 Sep 200628 Jun 2007Alveolus, Inc.Stent
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US831350529 Feb 200820 Nov 2012Aga Medical CorporationDevice for occluding vascular defects
US839867023 Jun 200619 Mar 2013Aga Medical CorporationMulti-layer braided structures for occluding vascular defects and for occluding fluid flow through portions of the vasculature of the body
US8747453 *18 Feb 200810 Jun 2014Aga Medical CorporationStent/stent graft for reinforcement of vascular abnormalities and associated method
US877797421 Jun 200715 Jul 2014Aga Medical CorporationMulti-layer braided structures for occluding vascular defects
US9034028 *13 Mar 201319 May 2015DePuy Synthes Products, Inc.Braid expansion ring with markers
US903972411 Sep 200826 May 2015Aga Medical CorporationDevice for occluding vascular defects
US944579817 Jan 201420 Sep 2016St. Jude Medical, Cardiology Division, Inc.Multi-layer braided structures for occluding vascular defects
US944579920 May 201420 Sep 2016St. Jude Medical, Cardiology Division, Inc.Multi-layer braided structures for occluding vascular defects
US20060241690 *23 Jun 200626 Oct 2006Aga Medical CorporationMulti-layer braided structures for occluding vascular defects and for occluding fluid flow through portions of the vasculature of the body
US20070265656 *21 Jun 200715 Nov 2007Aga Medical CorporationMulti-layer braided structures for occluding vascular defects
US20080200945 *29 Feb 200821 Aug 2008Aga Medical CorporationDevice for occluding vascular defects
US20090062841 *11 Sep 20085 Mar 2009Aga Medical CorporationDevice for occluding vascular defects
US20090210048 *18 Feb 200820 Aug 2009Aga Medical CorporationStent/stent graft for reinforcement of vascular abnormalities and associated method
US20140277376 *13 Mar 201318 Sep 2014DePuy Synthes Products, LLCBraid expansion ring with markers
Classifications
U.S. Classification623/1.19, 623/23.7
International ClassificationA61F2/00, A61L31/02, A61F2/88, A61F2/90
Cooperative ClassificationA61F2210/0076, A61F2220/0075, A61F2/915, A61F2/90, A61F2/88, A61F2002/91558, A61F2/844, A61L31/022, A61F2002/91533, A61F2002/9155, A61F2210/0019, A61F2002/91575, A61F2250/0042, A61F2/91, A61F2250/0029
European ClassificationA61L31/02B, A61F2/91, A61F2/844, A61F2/915, A61F2/88, A61F2/90
Legal Events
DateCodeEventDescription
6 Nov 2006ASAssignment
Owner name: BOSTON SCIENTIFIC SCIMED, INC., MINNESOTA
Free format text: CHANGE OF NAME;ASSIGNOR:SCIMED LIFE SYSTEMS, INC.;REEL/FRAME:018505/0868
Effective date: 20050101
Owner name: BOSTON SCIENTIFIC SCIMED, INC.,MINNESOTA
Free format text: CHANGE OF NAME;ASSIGNOR:SCIMED LIFE SYSTEMS, INC.;REEL/FRAME:018505/0868
Effective date: 20050101