Patent Application
20080275543
Not Applicable
Not Applicable
A stent is a medical device introduced to a body lumen and is well known in the art. Typically, a stent is implanted in a blood vessel at the site of a stenosis or aneurysm endoluminally, i.e. by so-called “minimally invasive techniques” in which the stent in a radially reduced configuration, optionally restrained in a radially compressed configuration by a sheath and/or catheter, is delivered by a stent delivery system or “introducer” to the site where it is required. The introducer may enter the body from an access location outside the body, such as through the patient's skin, or by a “cut down” technique in which the entry blood vessel is exposed by minor surgical means.
Stents, grafts, stent-grafts, vena cava filters, expandable frameworks, and similar implantable medical devices are radially expandable endoprostheses which are typically intravascular implants capable of being implanted transluminally and enlarged radially after being introduced percutaneously. Stents may be implanted in a variety of body lumens or vessels such as within the vascular system, urinary tracts, bile ducts, fallopian tubes, coronary vessels, secondary vessels, etc. They may be self-expanding, expanded by an internal radial force, such as when mounted on a balloon, or a combination of self-expanding and balloon expandable (hybrid expandable).
Stents may be created by methods including cutting or etching a design from a tubular stock, from a flat sheet which is cut or etched and which is subsequently rolled or from one or more interwoven wires or braids.
Within the vasculature, it is not uncommon for stenoses to form at a vessel bifurcation. A bifurcation is an area of the vasculature or other portion of the body where a first (or parent) vessel is bifurcated into two or more branch vessels. Where a stenotic lesion or lesions form at such a bifurcation, the lesion(s) can affect only one of the vessels (i.e., either of the branch vessels or the parent vessel) two of the vessels, or all three vessels. Many prior art stents however are not wholly satisfactory for use where the site of desired application of the stent is juxtaposed or extends across a bifurcation in an artery or vein such, for example, as the bifurcation in the mammalian aortic artery into the common iliac arteries.
The art referred to and/or described above is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. §1.56(a) exists.
All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
In at least one embodiment, the invention is directed to mechanisms that affect the elution rate of a therapeutic agent that has been deposited on the surface of at least a portion of a stent. Mechanisms include grooves formed in the therapeutic agent that is coating at least a portion of the surface of the stent.
In at least one embodiment, the invention is directed to the directional release of a therapeutic agent contained within a reservoir formed in at least one member of a stent.
These and other embodiments which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for further understanding of the invention, its advantages and objectives obtained by its use, reference can be made to the drawings which form a further part hereof and the accompanying descriptive matter, in which there is illustrated and described an embodiments of the invention.
A detailed description of the invention is hereafter described with specific reference being made to the drawings.
While this invention may be embodied in many different forms, there are described in detail herein specific 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.
For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.
To simplify the illustration of embodiments of the invention, the
A therapeutic agent 18 may be a drug or other pharmaceutical product such as non-genetic agents, genetic agents, cellular material, etc. Some examples of suitable non-genetic therapeutic agents include but are not limited to: anti-thrombogenic agents such as heparin, heparin derivatives, vascular cell growth promoters, growth factor inhibitors, Paclitaxel, etc. Where an agent includes a genetic therapeutic agent, such a genetic agent may include but is not limited to: DNA, RNA and their respective derivatives and/or components; hedgehog proteins, etc. Where a therapeutic agent 18 includes cellular material, the cellular material may include but is not limited to: cells of human origin and/or non-human origin as well as their respective components and/or derivatives thereof. Where the therapeutic agent 18 includes a polymer agent, the polymer agent may be a polystyrene-polyisobutylene-polystyrene triblock copolymer (SIBS), polyethylene oxide, silicone rubber and/or any other suitable substrate. Commonly assigned US Application Publication No 2006/0045901, hereby incorporated by reference in its entirety, contains a more extensive list of therapeutic agents 18 that may be used with the present invention.
In the embodiments, illustrated in
The coating of therapeutic agent 18 can have any depth or thickness and is deposited onto the surfaces of the member 14 by any means known in the art. As shown, for example in
In at least one embodiment a laser is used to make at least one depression 20 in the at least one coating of therapeutic agent 18. It is within the scope of the invention for any laser to be used. In at least one embodiment, crimping the coated stent 10 onto a forming mandrel at an elevated temperature forms at least one depression 20 into the coating of therapeutic agent 18.
The depressions 20 formed in the coating of therapeutic agent 18 can have any depth, as shown in
The depth of the depression 20 determines how much the depression 20 increases the surface area of the therapeutic agent 18. The depressions 20 in the therapeutic agent 18 in
Therapeutic agent 18 may be deposited in a reservoir positioned within the body of the member 14 instead onto the surface of the member 14.
Both reservoir 16 embodiments require a means by which the therapeutic agent 18 elutes from the reservoir 16. In at least one embodiment, a laser is used to drill holes 22 that form a passageway leading from the reservoir 16 to at least one surface of the member 14. Any laser may be used to drill the holes 22. If holes 22 are drilled on only one surface of the member 14, there is a directional release of therapeutic agent 18 from the reservoir 16. Thus, the therapeutic agent 18 can be targeted towards, for example, the luminal side of the member 14.
The elution rate of therapeutic agent 18 from the reservoir 16 is affected by the number of holes 22 and the size of the passageway of the holes 22. One way to increase the elution rate is to increase the number of holes 22. Another way to increase the elution rate is to increase the size of the passageway of the holes 22. In one embodiment, the laser produces holes 22 that are nano sized. In one embodiment, the laser produces holes 22 that are micro sized. Note that although the openings and passageway of the holes 22 can have any configuration, for example, but not limited to, round, square, rectangular, oval, oblong, bow-tie shaped, X-shaped, polygonal, irregular, and any combination thereof. The passageway of the hole 22 can have the same configuration as the opening, a different configuration from the openings of the hole 22 or more than one configuration.
Stents 10 have different regions and/or subregions. As a non-limiting example, the stent 10 in
As discussed in greater detail in U.S. patent application entitled Bifurcated Stent with Drug Wells for Specific Ostial, Carina, and Side Branch Treatment, Attorney Docket Number S63.2B-13099-US01, with inventors Dan Gregorich, Mike Meyer and Dave Friesen, hereby incorporated by reference herein in its entirety, a stent 10 can be used to deliver multiple therapeutic regimens from different regions and/or subregions of the stent 10. Examples of different regions of a stent (bifurcated and non-bifurcated) include, but are not limited to, the luminal side, the abluminal side, the proximal region (2), the distal region (6), the middle region (4), the main body of a bifurcated stent, the contralateral region of a bifurcated stent, the side branch of a bifurcated stent, members forming the side branch, and the perimeter member of a bifurcated stent.
As discussed above, the presence of depressions 20 in the therapeutic agent 18 affects the elution rate of the therapeutic agent 18. Similarly, the number and size of holes 22 from a reservoir 16 to the surface of the member 14 affects the elution rate of the therapeutic agent 18 from the reservoir 16. In at least one embodiment, at least one region of the stent 10 has a different elution rate of therapeutic agent 18 than at least one other region of the stent 10.
The following numbered statements characterize embodiments described above:
1. A method for manufacturing a reservoir in a member of a stent, comprising the steps of:
providing a stent, the stent having a plurality of members, each of the plurality of members having a first surface;
providing a laser;
directing the laser to the first surface; and
forming a reservoir in the first surface with the laser.
2. The method of statement 1, further comprising the steps of:
providing a therapeutic agent; and
depositing the therapeutic agent in the reservoir.
3. The method of statement 2 further comprising the step of:
depositing a coating of material over the reservoir, wherein the material is selected from at least one member of the group consisting of metal, metal oxides and ceramic materials.
4. The method of statement 3, the coating of material being deposited over the reservoir by plasma deposition.
5. The method of statement 3, further comprising the step of using the laser to bore at least one hole through the coating of material so that the hole extends from the first surface of the member to the reservoir, thereby providing a passageway from the reservoir to the first surface of the member.
6. The method of statement 3, the material being metal, wherein the metal is selected from at least one member of the group consisting of aluminium, magnesium, iron, tantalum, titanium, tungsten, and tungsten oxide, further comprising the step of oxidizing the coating of metal.
7. The method of statement 6, further comprising the step of using the laser to bore at least one hole through the coating of metal so that the hole extends from the first surface of the member to the reservoir, thereby providing a passageway from the reservoir to the first surface of the member.
8. A stent, the stent comprising a plurality of members, each of the plurality of members having a first surface and a body, the body having a volume, the body of at least one of the plurality of members defining a reservoir and at least one hole, the at least one hole extending from the reservoir to the first surface.
The inventive stents may be made from any suitable biocompatible materials including one or more polymers, one or more metals or combinations of polymer(s) and metal(s). Examples of suitable materials include biodegradable materials that are also biocompatible. By biodegradable is meant that a material will undergo breakdown or decomposition into harmless compounds as part of a normal biological process. Suitable biodegradable materials include polylactic acid, polyglycolic acid (PGA), collagen or other connective proteins or natural materials, polycaprolactone, hylauric acid, adhesive proteins, co-polymers of these materials as well as composites and combinations thereof and combinations of other biodegradable polymers. Other polymers that may be used include polyester and polycarbonate copolymers. Examples of suitable metals include, but are not limited to, stainless steel, titanium, tantalum, platinum, tungsten, gold and alloys of any of the above-mentioned metals. Examples of suitable alloys include platinum-iridium alloys, cobalt-chromium alloys including Elgiloy and Phynox, MP35N alloy and nickel-titanium alloys, for example, Nitinol.
The inventive stents may be made of shape memory materials such as superelastic Nitinol or spring steel, or may be made of materials which are plastically deformable. In the case of shape memory materials, the stent may be provided with a memorized shape and then deformed to a reduced diameter shape. The stent may restore itself to its memorized shape upon being heated to a transition temperature and having any restraints removed therefrom.
The inventive stents may be created by methods including cutting or etching a design from a tubular stock, from a flat sheet which is cut or etched and which is subsequently rolled or from one or more interwoven wires or braids. Any other suitable technique which is known in the art or which is subsequently developed may also be used to manufacture the inventive stents disclosed herein.
In some embodiments the stent may include one or more areas, bands, coatings, members, etc. that is (are) detectable by imaging modalities such as X-Ray, MRI, ultrasound, etc. In some embodiments at least a portion of the stent and/or adjacent assembly is at least partially radiopaque.
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. The various elements shown in the individual figures and described above may be combined or modified for combination as desired. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”.
Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.
This completes the description of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.
