Overlapping stent

A medical device may comprise a body portion and an outwardly deployable side branch structure, and may be formed from a first stent and a second stent. In some embodiments, the first stent and second stent may be connected by at least one connection. At least a portion of the second stent may be oriented within the first stent and may be coaxially aligned with the first stent. Either stent may include the side branch structure, and the stent not having side branch structure may include a side branch opening. The first and second stents may overlap at various locations to provide additional vessel support.

BACKGROUND OF THE INVENTION

1. Field of the Invention

In some embodiments this invention relates to implantable medical devices, their manufacture, and methods of use. Some embodiments are directed to delivery systems, such as catheter systems of all types, which are utilized in the delivery of such devices.

2. Description of the Related Art

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, collectively referred to hereinafter as stents, 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. Stents may be used to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. 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.

There remains a need for stents with innovative designs which combine excellent scaffolding support, compression resistance and side branch access.

BRIEF SUMMARY OF THE INVENTION

In at least one embodiment, the invention is directed to a medical device comprising a first stent and a second stent, wherein at least a portion of the second stent is oriented within the first stent. The first and second stents are coaxially aligned and either the first stent or the second stent includes an outwardly deployable side branch structure. In some embodiments, the first stent and the second stent may be connected by at least one connection.

In at least one other embodiment, a medical device comprises a first stent and a second stent. The first stent comprises a plurality of interconnected struts, the struts defining a plurality of cells including a side branch opening. The side branch opening comprises a cell having a different shape than other cells of the stent. The second stent comprises a plurality of interconnected struts, the struts defining a plurality of cells and a side branch structure having an outwardly deployable petal. At least a portion of the second stent is disposed within the first stent.

In further embodiments, the invention is directed to an assembly comprising a delivery catheter and a medical device comprising a first stent and a second stent, wherein at least a portion of the second stent is coaxially oriented within the first stent. The medical device further comprises an outwardly deployable side branch structure. The medical device is oriented about a distal portion of the catheter.

In further embodiments, the invention is directed to a method of stenting a vessel comprising providing a delivery catheter having an expandable medical device oriented about a distal end. The medical device comprises a first stent and a second stent, at least a portion of the second stent oriented within the first stent and coaxially aligned with the first stent. The medical device further comprises an outwardly deployable side branch structure. The method further comprises delivering the medical device to a deployment location in a bodily vessel, and expanding the medical device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows an embodiment of a medical device10which may comprise a stent, graft, stent-graft or other structure suitable for use within a bodily vessel20. The medical device10may comprise an expandable body portion12and an outwardly deployable side branch portion18. The medical device10may be deployed within a vessel20, for example with the body portion12oriented within a main branch vessel22and the side branch portion18deployed into a side branch vessel24.

The medical device10may comprise a first stent40and a second stent60. At least a portion of the second stent60may be oriented within the first stent40. The stents40,60may be coaxially aligned about a common longitudinal axis14. Thus, a central axis of the first stent40and a central axis of the second stent60may be collinear. Each stent may comprise any suitable stent framework pattern. In various embodiments, other suitable devices such as grafts, stent-grafts, etc., may be substituted for the traditional stent framework of a first stent40and/or a second stent60.

In some embodiments, one of the stents40,60may comprise a side branch opening, and one of the stents40,60may comprise a side branch structure having outwardly deployable petals64. As depicted inFIG. 1, the first or outer stent40includes a side branch opening42which is free of structural struts. The second or inner stent60includes side branch structure62having a plurality of outwardly deployable petals64. When the inner stent60includes side branch structure62, portions of the side branch structure62may deploy outwardly through the side branch opening42of the outer stent40.

The stents40,60may include body portions48,68which may each comprise a plurality of interconnected struts. Individually, the interconnected struts of either stent40,60may provide a respective amount of vessel support. Areas of the medical device10where the individual strut patterns overlap16, such as indicated by the shaded region inFIG. 1, desirably provide increased vessel coverage and support.

Various embodiments of a medical device10may be arranged to provide overlap16and greater vessel support at a number of areas near a vessel20bifurcation, such as an area21adjacent to the ostium near the contralateral ostial wall, an area23adjacent to the ostium near the carina, an area25opposite the ostium and contralateral ostial wall, and an area27opposite the ostium and carina.

FIG. 2ashows an embodiment of a flat pattern for a stent30which may be suitable for use as either a first stent40or a second stent60in a medical device10. The stent30may comprise a plurality of interconnected struts32. Areas between the interconnected struts32may comprise cells31.

The stent30may include a plurality of serpentine bands34which may extend about the circumference of the stent30. Each serpentine band34may comprise a plurality of band struts36connected by alternating proximal turns35and distal turns37. In some embodiments, the band struts36may be straight along their length. Adjacent serpentine bands34may be connected by connector struts38.

The stent30may further comprise a side branch opening42, which may comprise a side branch cell having a shape that is different from other cells31of the stent30. In some embodiments, a side branch opening42may be symmetrical about its center46.

FIG. 2bshows another embodiment of a flat pattern for a stent30which may be suitable for use as either a first stent40or a second stent60in a medical device10. The stent30may comprise interconnected struts32arranged to form cells31, serpentine bands34and connector struts38, for example as described with respect to the stent30ofFIG. 2a.

The stent30may further comprise a side branch structure62which may comprise a continuous strut member, or in some embodiments a plurality of strut members, which may extend in a generally serpentine fashion about the center63of the side branch structure62. While “serpentine” may be used describe most embodiments, the term is not intended to limit the invention. The side branch structure62may have any suitable size, shape and configuration of struts.

In some embodiments, the side branch structure62may define a plurality of side branch petals64which may have any suitable shape and may each be oriented in any suitable direction. A cell61of the side branch structure62may be different than any other cell31of the stent30.

Each petal64may comprise a plurality of struts66and at least one turn67. A strut66may be straight along its length, and may be oriented in any suitable direction. A turn67may be oriented in any suitable direction and in some embodiments may be oriented toward the center63of the side branch cell61. Petals64which are adjacent to one another about the side branch structure62may be connected to one another by a connecting portion69.

FIG. 2cshows an embodiment of a flat pattern for a medical device10comprising a first stent40and a second stent60. A person of ordinary skill in the art will recognize that the flat pattern may be rolled to form a cylindrical medical device10, and that rolling the flat pattern in one direction may produce a medical device10wherein the first stent40comprises an outer stent, whereas rolling the flat pattern in the opposite direction may produce a medical device10wherein the first stent40comprises an inner stent.

As depicted, the flat pattern for the second stent60may be positioned over the flat pattern for the first stent40. The second stent60may comprise a stent pattern as depicted inFIG. 2bhaving a side branch structure62including a plurality of petals64. The first stent40may comprise a stent pattern as depicted inFIG. 2ahaving a side branch opening42. The stents40,60may be oriented such that the center46of the side branch opening42of the first stent40is aligned with the center63of the side branch structure62of the second stent60.

In some embodiments, the first stent40may be connected to the second stent60by at least one and in some embodiments a plurality of connections52. A connection52may be located on any suitable area of the medical device10. A connection52may comprise any suitable connection between the stents40,60. In some embodiments, a connection52may comprise a welded, brazed or soldered connection, an adhesive connection, an encapsulated connection, a suture, ring, collar or band, rivets or pins, cooperative tabs and/or notches, friction pads, hook and loop fasteners, etc. In some embodiments, connections52may be insulated, wherein conductivity across the connection52is minimized, for example to enhance MRI compatibility.

Desirably, the orientation of the stent patterns40,60and the locations of the connections52allow the medical device10to provide greater vessel support than either stent40,60individually.

The serpentine bands34aof the first stent40may be staggered or offset from the serpentine bands34bof the second stent60in a direction about the circumference of the medical device10. Thus, a proximal turn35aof the first stent40may be aligned with a distal turn37bof the second stent60in a longitudinal direction of the medical device10.

Connections52between the stents40,60may be located along band struts36of the serpentine bands34. In some embodiments, the connections52may be located at the midpoint of a band strut36.

Medical devices10may be delivered to a deployment site using any suitable stent delivery system. In some embodiments, the first stent40and the second stent60may be delivered and deployed while maintaining a coaxial orientation. In some embodiments, a first stent40and a second stent60may be delivered to the deployment site separately or independently of one another. For example, the first stent40may be delivered to the deployment site, properly oriented and expanded. The second stent60may then be delivered to the deployment site, oriented coaxially within the first stent40and expanded.

FIG. 2dshows a portion of a medical device according toFIG. 2cafter expansion. The staggered orientation of the serpentine bands34a,34bof the first stent40and the second stent60, and the locations of the connections52, provide greater vessel support than either stent40,60individually. It is also clear fromFIG. 2dthat at least a portion of the interconnected strut pattern of the first stent40may comprise a mirror image of a portion of the interconnected strut pattern of the second stent60.

In some embodiments, it is desirable for portions of the stents40,60to have similar expansion characteristics, such as change in diameter, change in length, etc. For example, the serpentine bands34of the stents40,60are similarly shaped, and will experience a substantially equal amount of diameter increase and a substantially equal amount of size change along the length of the medical device during expansion.

Desirably, a line oriented in a radial direction of the medical device10in some locations may pass through a cell31of the second stent60and intersect a strut32of the first stent40. In some other locations, a radial line may pass through a cell31of the first stent40and intersect a strut32of the second stent60. In other locations, a radial line may pass through cells31of both stents40,60. In still other locations, a radial line may intersect struts32of both stents40,60.

FIG. 2eshows a flat pattern for a medical device10similar toFIG. 2c, with the locations of the stent patterns40,60reversed, such that the flat pattern for the first stent40may be positioned over the flat pattern for the second stent60. While a person of ordinary skill in the art will recognize that the flat patterns ofFIGS. 2cand2emay each be selectively rolled to form a device wherein either stent40,60may comprise the outer stent,FIG. 2eis shown for clarification purposes.

FIG. 3ashows another embodiment of a portion of a stent pattern comprising a plurality of interconnected struts32which may be suitable for use as a first stent40. The pattern may further comprise longitudinal struts74and joining struts76, which may meet at an intersection80.

FIG. 3bshows another embodiment of a portion of a stent pattern comprising a plurality of interconnected struts32which may be suitable for use as a second stent60. The pattern of the second stent60may comprise a mirror image of the pattern of the first stent40as depicted inFIG. 3a. Thus, the joining struts76shown inFIG. 3bmay be canted with an orientation that is reversed from the orientation shown inFIG. 3a.

FIG. 3cshows a portion of an embodiment of a medical device10comprising the stent patterns40,60ofFIGS. 3aand3b. The first stent40may overlap the second stent60. The stents40,60may be oriented such that an intersection80abetween a longitudinal strut74and a joining strut76of the first stent40is aligned with an intersection80bof the second stent60.

Connections52between the stents40,60may be placed in any suitable locations, such as where intersections80a,80bmeet, and/or at locations where joining struts76cross.

FIG. 3dshows a portion of another embodiment of a medical device10comprising the stent patterns40,60ofFIGS. 3aand3b. The first stent40may overlap the second stent60. The location of the first stent40with respect to the second stent60may be offset from the location shown inFIG. 3c. In the embodiment ofFIG. 3d, intersections80aof the first stent40may be offset from intersections80bof the second stent.

In some embodiments of a medical device comprising a first stent40and a second stent60, the second stent60may comprise a partial stent or a plurality of struts connected to the first stent40in select locations to provide additional vessel support at select locations of the medical device10.

FIG. 4shows an embodiment of a flat pattern for a medical device10comprising a first stent40and a second stent60. The second stent60may comprise interconnected struts32that are selectively designed to provide additional vessel support at predetermined locations. The first stent40and the second stent60may be connected by at least one and desirably a plurality of connections52as herein described.

Struts32of the second stent60may have any suitable size and shape. Struts32of the second stent60may be located in proximity to any portion of the first stent40and may provide addition vessel support in any suitable location. The embodiment ofFIG. 4includes struts32oriented to provide additional vessel support to an area21adjacent to the ostium near the contralateral ostial wall, an area23adjacent to the ostium near the carina23, an area25opposite the ostium and contralateral ostial wall, and an area27opposite the ostium and carina as also depicted inFIG. 1.

FIG. 5shows an example of another embodiment of structure of a first stent40and a second stent60that may be used to form a medical device. The stents40,60may be connected by at least one connection52. The first stent40may include a serpentine band34ahaving a predetermined wavelength, frequency and amplitude. The second stent60may include a serpentine band34bthat may have a wavelength, frequency and/or amplitude that is different from the serpentine band34aof the first stent40.

In some embodiments, the wavelength, frequency and/or amplitude of a serpentine band34of either stent40,60may change.

In some embodiments, any area of a medical device10may include areas where one stent40,60has a greater strength than the other stent. In some embodiments, a first stent40may be stronger than a second stent60in some areas, and the second stent60may be stronger than the first stent40in other areas. In various embodiments, a stronger stent may have any suitable design to provide the greater strength, such as being made from a different material, having larger strut members, such as wider or thicker struts, etc. In some embodiments, a first stent40may comprise a plurality of interconnected struts designed primarily to provide a high amount of vessel support, while a second stent60may comprise a plurality of interconnected struts designed primarily to provide structural strength.

FIG. 6shows a portion of another embodiment of a medical device10comprising a first stent40and a second stent60. Each stent40,60may include serpentine bands34comprising alternating proximal turns35and distal turns37. Connections52between the stents40,60may be located where a turn35a,37aof the first stent40meets a turn35b,37bof the second stent60. For example, a connection52may be located where a distal turn37aof the first stent40meets a proximal turn35bof the second stent60.

A second stent60may include a serpentine band34bthat connects in one or more locations to one serpentine band34aof the first stent40and in one or more locations to another serpentine band34aof the first stent40.

A medical device10may include stents40,60having any suitable strut design. Some stent designs which include stent side branch structure62(seeFIG. 1) are described in U.S. patent application Ser. Nos. 11/138,022, 11/138,202 and 11/138,196, the entire disclosures of which are hereby incorporated herein in their entireties.

In some embodiments, both stents40,60may include side branch structure62, and the side branch structure of one stent desirably compliments the design of the side branch structure of the other stent to provide vessel support to areas such as the carina and contralateral ostial wall.

A first stent40and a second stent60may further include complimentary designs over at least a portion of the medical device10. Some further examples of complimentary stent designs suitable for use as inner and outer connected stents are described in U.S. patent application Ser. No. 10/864,665, the entire disclosure of which is hereby incorporated herein in its entirety.

FIG. 7shows an embodiment of a medical device8oriented within a bodily vessel20. The medical device8may comprise a main branch portion72and a side branch portion82. Each portion72,82may comprise a stent, a graft, a stent-graft or any other suitable vessel supporting structure.

The main branch portion72may include a side branch structure62having outwardly deployable petals64and may comprise an embodiment of a medical device10as herein described, which may include a first stent40and a second stent60(seeFIG. 2c). In some embodiments, the main branch portion72may comprise any suitable portion of a medical device10as described herein, such as a first stent40or a second stent60, or any other suitable stent structure.

The side branch portion82may comprise any suitable stent structure, for example comprising a plurality of interconnected struts. In some embodiments, a stent oriented in a side branch vessel24may include structure that extends into the main branch vessel22, for example as disclosed in U.S. Pat. No. 6,896,699, the entire disclosure of which is hereby incorporated herein in its entirety.

Areas where structure of the main branch portion72and side branch portion82overlap16desirably provide increased vessel coverage and support. Thus, the overlap may provide increased support in areas such as the contralateral ostial wall26and areas near the carina28.

Desirably, a line oriented in a radial direction of the side branch portion82in some locations of the overlap16may pass through a cell of the side branch portion82and intersect a strut of the main branch portion72. In some other locations, a radial line may pass through a cell of the main branch portion72and intersect a strut of the side branch portion82. In other locations, a radial line may pass through cells of both portions72,82. In still other locations, a radial line may intersect struts of both portions72,82.

In some embodiments, at least a portion of interconnected struts of the side branch portion82may be shaped similarly to a portion of interconnected struts of the main branch portion72. In some embodiments, at least a portion of interconnected struts of the side branch portion82may comprise a mirror image of a portion of interconnected struts of the main branch portion72.

The main branch portion72may be delivered to a deployment location and deployed, which may comprise increasing the diameter of the main branch portion72, and may further comprise deploying the side branch structure62outwardly into a side branch vessel24. The side branch portion82may be delivered to its deployment location relative to the main branch portion72, and may be deployed, which may comprise increasing the diameter of the side branch portion82. In some embodiments, deployment of the side branch portion82may further comprise orienting the side branch portion82such that struts of the side branch portion82mesh with struts of the main branch portion72to provide additional vessel coverage. In some embodiments, deployment of the side branch portion82may further comprise properly orienting any portion of the side branch portion82which extends into the main branch vessel22.

The invention is also directed to delivery systems used in delivering a medical device10to a deployment location, and to methods of stenting a bifurcation using a medical device10as described herein.

FIG. 8shows a longitudinal cross-sectional view of an example of a catheter assembly84that is representative of an over-the-wire (OTW) or single-operator-exchange (SOE) angioplasty balloon catheter. Such balloon catheters are discussed, for example, in U.S. Pat. Nos. 6,113,579, 6,517,515 and 6,514,228, the entire disclosures of which are incorporated herein by reference in their entireties. The catheter84may include an elongate shaft assembly86and an OTW-type manifold assembly88connected to a proximal end of shaft assembly86. The manifold assembly88may further comprise a strain relief device91. The shaft assembly86may comprise an outer tube92coaxially disposed about an inner tube94. The inner tube94may include an interior lumen which may comprise a guide wire lumen. An area between the inner tube94and the outer tube92may comprise an inflation lumen96which may be in fluid communication with an interior portion of an inflation balloon90.FIG. 8is provided only as an example of one type of catheter assembly suitable for use with a medical device10, and is not intended to limit the scope of the present invention.

FIG. 9shows another embodiment of a catheter assembly84that may be used in delivering a medical device10to a deployment site. The assembly84may include a first inflatable portion98and a second inflatable portion99. The second inflatable portion99may be used to deploy the side branch structure62of a medical device10into a side branch vessel. Similar catheter assemblies and methods of use are disclosed in US Published Application No. 20050060027, the entire disclosure of which is hereby incorporated herein by reference in its entirety.

The inventive medical devices 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/bioabsorbable materials that are also biocompatible. The term biodegradable is intended to mean 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. Further materials may include MRI compatible materials such as niobium-zinc.

The inventive medical devices 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 medical devices 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 medical device, the delivery system or other portion of the assembly 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, the entire stent may be MRI compatible. In some embodiments at least a portion of the stent and/or adjacent assembly is at least partially radiopaque.

In some embodiments the at least a portion of the medical device is configured to include one or more mechanisms for the delivery of a therapeutic agent. Often the agent will be in the form of a coating or other layer (or layers) of material placed on a surface region of the stent, which is adapted to be released at the site of the stent's implantation or areas adjacent thereto.

A therapeutic agent 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 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 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.

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”.

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.