The following description relates primarily to the positioning and operation of an intravascular stent for treating an ischemic coronary artery of a patient after a myocardial infarction. The treatment may occur, for example, before, during, and/or after a CABG or PTCA procedure in an effort to salvage and/or rehabilitate myocardial tissue. Those skilled in the art will recognize that although the present invention is described primarily in the context of localized delivery of a stent in a coronary blood vessel with a specific intravascular device, the Inventors contemplate numerous other applications of a prosthetic device in accordance with said invention.
For example, an intravascular stent according to the present invention may be deployed within another arteriole or venous blood vessel, or adapted as an intraluminal device for use in another vessel such as the intestine, air duct, esophagus, bile duct, and the like. Any number of devices capable of performing the prescribed method(s) may be adapted for use with the present invention. Furthermore, the deployment strategies, treatment site and tissues, and therapeutic agents are not limited to those described. Numerous modifications, substitutions, additions, and variations may be made to the devices and methods while providing a stent in accordance with the present invention.
Referring to the drawings, wherein like reference numerals refer to like elements,
In one embodiment, the catheter 20 may comprise an elongated tubular member manufactured from one or more polymeric materials, sometimes in combination with metallic reinforcement. In some applications (such as smaller, more tortuous arteries), it is desirable to construct the catheter from very flexible materials to facilitate advancement into intricate access locations. Numerous over-the-wire, rapid-exchange, and other catheter designs are known and may be adapted for use with the present invention. Catheter 20 may be secured at its proximal end to a suitable Luer fitting 22. Catheter 20 may be manufactured from a material such as a thermoplastic elastomer, urethane, polymer, polypropylene, plastic, ethelene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), nylon, Pebax® resin, Vestamid® nylon, Tecoflex® resin, Halar® resin, Hyflon® resin, Pellathane® resin, combinations thereof, and the like. Catheter 20 may include an aperture formed at a distal rounded end allowing advancement over a guidewire 24.
In one embodiment, the stent 40 embodying features of the invention can be readily delivered to a desired body lumen, such as a coronary artery (peripheral vessels, bile ducts, etc.), by mounting the stent 40 on an expandable member of a delivery catheter, for example the balloon 30, and advancing the catheter 20 and stent assembly through the body lumen to a target site. Generally, the stent 40 is compressed or crimped onto the balloon 30 portion of the catheter 20 so that the stent 40 does not move longitudinally relative to the balloon 30 portion of the catheter 20 during delivery through the arteries, and during expansion of the stent 40 at the target site. In another embodiment, the stent may be manufactured from a resilient material and expand at the target site after it is properly positioned. During the deployment process, for example, a sheath enclosing a crimped stent may be withdrawn thereby allowing the stent to expand outwardly into contact with the vessel wall. Typically, self-expanding stents do not require a balloon.
Balloon 30 may be any variety of balloons capable of expanding the stent 40. Balloon 30 may be manufactured from any sufficiently elastic material such as polyethylene, polyethylene terephthalate (PET), nylon, or the like. Stent 40 may be expanded with the balloon 30. System 10 may optionally include a sheath (not shown) to retain the stent 40 in a collapsed state and to prevent contact with surfaces, such as a vessel wall, during advancement through a vessel lumen and subsequent deployment. Once the stent 40 is properly positioned, the sheath may be retracted thereby allowing the stent to assume its expanded shape. In addition, once the stent 40 is properly positioned within the vasculature, the balloon 30 and stent 40 are expanded together. Balloon 30 may then be deflated and retracted thereby allowing the stent 40 to remain in a deployed configuration. Alternatively, for self-expanding stents balloon or other expandable members are typically not used. Instead, a sheath covering the compressed stent may be withdrawn (at the treatment site) thereby allowing the stent to expand to its naturally larger shape into contact with the vessel. The advancement, positioning, and deployment of stents and like devices are well known in the art. In addition, those skilled in the art will recognize that numerous devices and methodologies may be adapted for deploying the stent in accordance with the present invention.
The terms “catheter” and “stent”, as used herein, may include any number of intravascular and/or implantable prosthetic devices (e.g., a stent-graft); the examples provided herein are not intended to represent the entire myriad of devices that may be adapted for use with the present invention. Although the devices described herein are primarily done so in the context of deployment within a blood vessel, it should be appreciated that intravascular and/or implantable prosthetic devices in accordance with the present invention may be deployed in other vessels, such as a bile duct, intestinal tract, esophagus, airway, etc. Further, the terms “biodegradable” and “non-biodegradable”, as used herein, refer to a relative stabilities of substances when positioned within a living being. For example, a biodegradable substance will degrade (i.e., break down) at a faster rate than a non-biodegradable substance. A non-biodegradable substance, however, may, eventually degrade given a sufficient amount of time.
Referring to
In one embodiment, at least one of the first and second end portions 44, 46 include an alternative strut configuration in comparison to the center portion 48. As such, the first and second end portions 44, 46 match the compliance of the blood vessel.
In one embodiment of the alternative strut configuration, as shown in
In another embodiment of alternative strut configuration, as shown in
In another embodiment of alternative strut configuration, the thickness of the struts located in the first and second end portions 44b, 46b are substantially less than the thickness of the struts located in the center portion 48b of stent 40b. In one embodiment, for example, struts 51b at first and second end portions 44b, 46b are relatively thinner in comparison to struts 53b at center portion 48b. In one embodiment, struts 51b are about one half the thicknesses of struts 53b. One skilled in the art can appreciate that a number of strut configurations may provide a modified strut width and is not limited to the embodiment provided herein.
In yet another embodiment of alternative strut configuration, as shown in
In one embodiment, at least one of the first and second end portions 44, 46 include alternative strut materials from the center portion. As such, the first and second end portions 44, 46 match the compliance of the blood vessel.
In one embodiment of alternative strut materials, as shown in
In one embodiment, at least one of the first and second end portions 44, 46 of the stent 40 include an alternative strut processing condition from the center portion 48. As defined herein, an alternative strut processing condition refers to one or more chemical or physical processes applied to the stent 40 material(s) of the first and/or second end portions 44, 46 as compared to the center portion 48.
In one embodiment of an alternative strut processing condition, a polymeric stent 40 includes edges that are annealed at the first and second end portions 44d, 46d. Specifically, the first and second end portions 44d, 46d are heated and then cooled quickly to remove polymer crystallinity in the stent 40 material thereby increasing the flexibility of the constituent material. One skilled in the art will recognize an annealing process may be applied along various degrees to the first and second end portions 44d, 46d. For example, the first and second end portions 44d, 46d may be annealed to the same extent or at a gradually decreasing level from the edges toward the center portion 48d.
In another embodiment of an alternative strut processing condition, a metallic stent 40 includes a middle segment 48c that has been cold-worked through processes including swaging or rolling. In another embodiment of an alternative strut processing conditions, a cold-worked metallic stent 40 includes end portions 44d, 46d that have been annealed at elevated temperatures to reduce dislocation densities in the material. One skilled in the art will recognize an annealing process may be applied along various degrees to the first and second end portions 44d, 46d. For example, the first and second end portions 44d, 46d may be annealed to the same extent or at a gradually decreasing level from the edges toward the center portion 48d.
Those skilled in the art will appreciate that the compliance-graded stent 40 is not limited to the alternative strut configuration, alternative strut materials, and alternative strut processing condition embodiment provided herein. Numerous other strategies are contemplated by the Inventor for providing a compliant stent and fall within the spirit and scope of the present invention.
In one embodiment, as shown in
In one embodiment, the therapeutic agent may additionally include one or more polymers, solvents, a component thereof, a combination thereof, and the like. For example, the therapeutic agent may include a mixture of a gene therapy agent/drug and a polymer dissolved in a compatible liquid solvent as known in the art. Polymer(s) provide a matrix for incorporating the gene therapy agent/drug within a coating and, optionally, provide means for slowing the elution of an underlying therapeutic agent when it comprises a cap coat. Some exemplary biodegradable polymers that may be adapted for use with the present invention include, but are not limited to, polycaprolactone, polylactide, polyglycolide, polyorthoesters, polyanhydrides, poly(amides), poly(alkyl-2-cyanocrylates), poly(dihydropyrans), poly(acetals), poly(phosphazenes), poly(dioxinones), trimethylene carbonate, polyhydroxybutyrate, polyhydroxyvalerate, their copolymers, blends, and copolymers blends, combinations thereof, and the like.
Solvents are used to dissolve the therapeutic agent(s), gene therapy agent(s), and polymer(s) to provide a therapeutic agent coating solution. Some exemplary solvents that may be adapted for use with the present invention include, but are not limited to, acetone, ethyl acetate, tetrahydrofuran (THF), chloroform, N-methylpyrrolidone (NMP), methylene chloride, and the like.
Those skilled in the art will recognize that the nature of the gene therapy agent, drug, and polymer may vary greatly and are typically formulated to achieve a given therapeutic effect, such as limiting restenosis, thrombus formation, hyperplasia, etc. Once formulated, a therapeutic agent solution (mixture) comprising the coating may be applied to the stent 40 by any of numerous strategies known in the art including, but not limited to, spraying, dipping, rolling, nozzle injection, and the like. Numerous strategies of applying the coating in accordance with the present invention are known in the art.
In one embodiment, two or more therapeutic agents are incorporated into the stent 40 and are released having a multiple elution profile. For example, a first therapeutic agent disposed on the stent 40 is released to reduce inflammation. The first agent may be released on a short-term basis to overcome surgical trauma of the treatment. A second therapeutic agent may be disposed underneath the first therapeutic agent on the stent 40 for reducing endovascular restenosis. After the first therapeutic agent has been delivered, the second therapeutic agent is released on a longer-term basis.
At step 810, at least one therapeutic agent may be applied to the stent 40 prior to deployment. Numerous processes are known in the art for applying the therapeutic agent to the stent 40. Once formulated, a therapeutic agent (mixture) comprising the coating(s) may be applied to the stent by any of numerous strategies known in the art including, but not limited to, spraying, dipping, rolling, nozzle injection, and the like. It will be recognized that the at least one therapeutic agent coating may be alternatively layered, arranged, configured on/within the stent depending on the desired effect (i.e., The coatings may be positioned on various portions of the stent 40). Before application, one or more primers may be applied to the stent to facilitate adhesion of the at least one therapeutic agent coating. Numerous strategies of applying the primer(s), therapeutic agent coating(s), and cap coat(s) in accordance with the present invention are known in the art. Various drug elution profiles may be achieved by differentially coating/impregnating the therapeutic agent(s) within the polymeric structure and/or on the stent as understood by one skilled in the art. Specifically, those skilled in the art will recognize that the nature of the drugs, polymers, and solvent may vary greatly and are typically formulated to achieve a given therapeutic effect, such as limiting restenosis, thrombus formation, hyperplasia, etc. Once formulated, a therapeutic agent (mixture) comprising the coating(s) may be applied to the stent by any of numerous strategies known in the art including, but not limited to, spraying, dipping, rolling, nozzle injection, and the like, or, alternatively, added to the polymer of the stent during manufacture. It will be recognized that the at least one therapeutic agent coating may be alternatively layered, arranged, configured on/within the stent depending on the desired effect. Before application, one or more primers may be applied to the stent to facilitate adhesion of the at least one therapeutic agent coating. Once the at least one therapeutic agent coating is/are applied, it/they may be dried (i.e., by allowing the solvent to evaporate) and, optionally, other coating(s) (e.g., a “cap” coat) added thereon. Numerous strategies of applying the primer(s), therapeutic agent coating(s), and cap coat(s) in accordance with the present invention are known in the art.
The method may end at step 812 and be repeated as necessary.
While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications may be made without departing from the spirit and scope of the invention. The intraluminal stent delivery system, stent, and method of deploying the stent of the present invention are not limited to any particular design, configuration, methodology, or sequence. For example, the catheter, stent, frame, first end portion, second end portion, and center portion may vary without limiting the utility of the invention. Furthermore, the described order of the method may vary and may include additional steps to manufacture the stent.
Upon reading the specification and reviewing the drawings hereof, it will become immediately obvious to those skilled in the art that myriad other embodiments of the present invention are possible, and that such embodiments are contemplated and fall within the scope of the presently claimed invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.