US20070112418A1

US20070112418A1 - Stent with spiral side-branch support designs

Info

Publication number: US20070112418A1
Application number: US11/273,186
Authority: US
Inventors: Tracee Eidenschink; Michael Meyer; Matt Heidner; Daniel Gregorich; Amnon Yadin; Thomas Broome; Todd Bethel
Original assignee: Boston Scientific Scimed Inc
Current assignee: Boston Scientific Scimed Inc
Priority date: 2005-11-14
Filing date: 2005-11-14
Publication date: 2007-05-17
Also published as: CA2624607A1; US7842081B2; JP2009515589A; EP1948100A1; US20070112419A1; WO2007055768A1

Abstract

An expandable stent may be made having an expandable spiral side branch support section having a spiral configuration and disposed about a center point. The expandable spiral side branch support section is configured to expand outward to allow for the formation of a bifurcated stent with a side branch.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

BACKGROUND OF THE INVENTION

Stents, grafts, stent-grafts, vena cava filters 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, etc. Stents may be used to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. They may be self-expanding or expanded by an internal radial force, such as when mounted on a balloon.
Stents are generally tubular devices for insertion into body lumens. Balloon expandable stents require mounting over a balloon, positioning, and inflation of the balloon to expand the stent radially outward. Self-expanding stents expand into place when unconstrained, without requiring assistance from a balloon. A self-expanding stent is biased so as to expand upon release from the delivery catheter. Some stents may be characterized as hybrid stents which have some characteristics of both self-expandable and balloon expandable stents.
Stents may be constructed from a variety of materials such as stainless steel, Elgiloy, nitinol, shape memory polymers, etc. Stents may also be formed in a variety of manners as well. For example, a stent may be formed by etching or cutting the stent pattern from a tube or section of stent material; a sheet of stent material may be cut or etched according to a desired stent pattern whereupon the sheet may be rolled or other wise formed into the desired tubular or bifurcated tubular shape of the stent; one or more wires or ribbons of stent material may be braided or otherwise formed into a desired shape and pattern.
Within the vasculature however, 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 bifurcations, 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.
All U.S. 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.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.

BRIEF SUMMARY OF THE INVENTION

The present invention includes many different embodiments. Various embodiments of the invention are directed to designs of stents, bifurcated stents and/or the methods utilized to deliver a bifurcated stent to a bifurcation site.
In one or more embodiments, the invention is directed to an expandable stent having a flow path therethrough and an exterior surface and an interior surface, a constant inner diameter and an outer diameter. The stent comprises an expandable spiral side branch support section having a spiral configuration and disposed about a center point. The center point is located at a first longitudinal coordinate and circumferential coordinate. The spiral side branch support section comprises at least one spiral arm forming a curve extending at least partially around the center point. The at least one spiral arm has a first end and a second end, the second end positioned closer to the center point than the first end. The stent has no more than one spiral branch support section disposed about a center point located at the first longitudinal coordinate.
In one or more embodiments, the invention is directed to an expandable stent having a longitudinal flowpath therethrough and having an exterior surface and an interior surface, an inner diameter and an outer diameter. The stent comprises an expandable spiral side branch support section which lies flush with the inner surface of the remainder of the stent. The expandable spiral side branch has a spiral configuration and is disposed about a center point located at a first longitudinal coordinate and circumferential coordinate. The spiral side branch support section comprises at least one spiral arm forming a curve extending at least partially around the center point. The at least one spiral arm has a first end and a second end, the second end positioned closer to the center point than the first end. The stent has no more than one spiral branch support section disposed about a center point located at the first longitudinal coordinate.
The invention is also directed to bifurcated stents formed by providing any of the expandable stents disclosed herein, expanding the stent to a first diameter and expanding the at least one spiral arm outward to define a second flowpath which branches off the longitudinal flowpath.
The invention is also directed to, in combination, a catheter and an expandable stent having a tubular surface disposed about a longitudinal flowpath, the tubular surface including at least one arm which is arranged along the surface about an opening, the opening having a first size in an unexpanded state of the stent, the at least one arm arranged to define a spiral, the expandable stent disposed about the catheter, the catheter including an elongated member which extends through the expandable spiral side branch support section.
Additional details and/or embodiments of the invention are discussed below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

A detailed description of the invention is hereafter described with specific reference being made to the drawings.
FIG. 1 is a side view of the stent with a spiral side branch section that has one spiral arm in the unexpanded state.
FIG. 2 is a view of the stent with a spiral side branch section that has a plurality of spiral arms in the expanded state.
FIG. 3 is a side view of the stent with a spiral side branch section that has a circumferential member engaged to a plurality of spiral arms in the unexpanded state.
FIG. 4 is a side view of the stent with another embodiment of the spiral side branch section of FIG. 3 in the unexpanded state.
FIG. 5 is a side view of the stent with a spiral side branch section that has a plurality of spiral arms with free ends in the unexpanded state.
FIG. 6 is a side view of the stent with a spiral side branch section that has a plurality of spiral arms and a circumferential member with a serpentine shape in the unexpanded state.
FIG. 7 is a side view of the stent with a spiral side branch section that has a plurality of serpentine shaped circumferential members and a plurality of spiral arms in an unexpanded state.
FIG. 8 a is a side view of the stent with a spiral side branch section that has a circumferential member with a locking mechanism and a plurality of spiral arms in an unexpanded state.
FIG. 8 b shows a locking mechanism which may be used in the stent of FIG. 8 a.
FIG. 8 c shows the locking mechanism of FIG. 8 b immediately prior to engagement
FIG. 9 is a side view of the stent in FIG. 8 a with a radiopaque marker on the circumferential member.
FIG. 10 a is a side view of the stent of FIG. 8 a with the spiral side branch section in an expanded state, the spiral arms are straight when in an expanded state.
FIG. 10 b is a side view of the stent of FIG. 8 a with the spiral branch section in an expanded state, the spiral arms are curved when in an expanded state.
FIG. 11 is a side view of the stent with a spiral side branch section in an unexpanded state consisting of four spiral arms.
FIG. 12 is a side view of the stent with a spiral side branch section that has four spiral arms, each spiral arm having an opening in the width of the spiral arm, in an unexpanded state.
FIG. 13 is a side view of the stent with the spiral side branch section of FIG. 11 in an expanded state.
FIG. 14 is a side view of an embodiment of the stent with a spiral side branch section that has a plurality of serpentine shaped circumferential members and a plurality of spiral arms in an unexpanded state.
FIG. 15 is a perspective view of the embodiment in FIG. 14 in an expanded state.
FIG. 16 is a side view of an embodiment of the stent with a spiral side branch section that has a plurality of interconnected spiral arms in an unexpanded state.
FIG. 17 is a perspective view of the embodiment in FIG. 16 in an expanded state.

DETAILED DESCRIPTION OF THE INVENTION

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 purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.
As used herein the term ‘stent’ refers to an expandable prosthesis for implantation into a body lumen or vessel and includes devices such as stents, grafts, stent-grafts, vena cava filters, expandable frameworks, etc.
Referring now to the drawings which are for the purposes of illustrating embodiments of the invention only and not for purposes of limiting same, in at least one embodiment of the invention, an example of which is shown in FIG. 1, stent 20, shown in side view, comprises an expandable spiral side branch support section 24. Expandable spiral side branch support section 24 has a spiral configuration and is disposed about a center opening 32 and center point. The center point is located at a first longitudinal coordinate and a first circumferential coordinate. The longitudinal coordinate indicates where, along the length of the stent, the center point is located. The circumferential coordinate indicates where, about the circumference of the stent, the center point lies. The spiral side branch support section 24 comprises at least one spiral arm 28 forming a curve extending at least partially around the center point. The at least one spiral arm has a first end and a second end. One of the two ends is positioned closer to the center point than the other of the two ends.
The stent of FIG. 1 has no more than one spiral branch support section 24 located at the first longitudinal coordinate. Thus, there are no other spiral branch support sections which are disposed about the circumference of the stent and located at the first longitudinal coordinate. In other embodiments of the invention, additional spiral branch support sections may be located at the first longitudinal coordinate or any other longitudinal and circumferential coordinate. Moreover, the spiral side branch support section 24 has only one spiral arm 28.
The outer support member 30 can have any shape, for example a shape that corresponds to the cellular design of the primary stent section 22, a circular shape, or a serpentine shape. The outer support member 30 of FIGS. 2-13 has a circular shape. The outer support member 30 of FIGS. 2-13 has at least one spiral arm 28 extending therefrom. If the spiral side branch section 24 has circumferential members 34, the circumferential members 34 can have any shape. In at least one embodiment, all the circumferential members 34 have the same shape.
Any suitable stent geometry may be used for the main body of the stent. The pattern of interconnected serpentine bands 19 shown is shown by way of example only. The struts that form the serpentine band may be straight as shown in FIG. 1 or may be bent. The stent of FIG. 14 shows straight and bent struts.
If the spiral arm 28 has sufficient length, the spiral arm 28 will form a spiral around the opening 32 in the spiral side branch section 24. Each spiral arm 28 has a distal end 50 and a proximal end 52. The distal end 50 of the spiral arm 28 is positioned closer to the center of the opening 32 of the spiral side branch section 24 than the proximal end 52.
A non-bifurcated stent is formed when only the primary branch section 22 is in an expanded state. A bifurcated stent is formed when both the primary branch section 22 and the spiral side branch section 24 are in an expanded state.
In FIG. 1, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30 and one spiral arm 28. The proximal end 52 of the spiral arm 28 is engaged to the outer support member 30. The distal end 50 of the spiral arm 28 is closer to the center of the opening 32 of the spiral side branch section 24 than the proximal end 52.
More generally, the stent of FIG. 1 may have more than one spiral side branch section. Where there is a plurality of side branch sections, the side branches may be disposed at different locations along the length of the stent, different circumferential locations about the stent or both. Where a plurality of side branch sections is present, the side branches may be of the same length or of different lengths. The side branch sections may have only one spiral arm per side branch section or one or more of the side branch sections may each have a plurality of spiral arms.
The stent of FIG. 1 may prove to be advantageous as compared with some of the known petal designs for bifurcated stents. In the case of the latter stents, some of the petals typically have to be bent at an angle in excess of 90 degrees resulting in high stresses on those petals. No such extreme bending occurs during deployment of the stent of FIG. 1 as well as during deployment of other stents disclosed herein.
Another embodiment of the invention is shown at 20 in FIG. 2. Stent 20, shown in an expanded state, has a primary branch section 22 and a spiral side branch section 24 that extends from the primary branch section 22. The primary branch section 22 is a substantially tubular body disposed about a longitudinal axis. Those skilled in the art will recognize that the pattern of the primary branch section 22 can have any cellular design. In some embodiments of the invention, the primary branch section 22 may be characterized as a substantially solid or porous tubular member.
The expandable primary branch section 22 has a first diameter in an unexpanded state (not shown) and a second diameter in an expanded state. In an unexpanded state of the stent, the entirety of the spiral side branch section 24 forms a part of the surface of the substantially tubular body of the primary branch section 22. The unexpanded version of the stent has only one longitudinal flowpath and does not include a portion which branches off of the longitudinal flowpath.
The spiral side branch section 24 has an outer support member 30 and at least one spiral arm 28 that curves around an opening 32 in the spiral side branch section 24.
In FIG. 2 the primary branch section 22 and the spiral side branch section 24 are shown in an expanded state. The spiral side branch section 24 of the stent 20 has an outer support member 30 and a plurality of spiral arms 28. The proximal end 52 of each spiral arm 28 is engaged to the outer support member 30. When the spiral side branch section 24 is in an expanded state the spiral arms 28 form a plurality of helices depending upon the number of spiral arms 28.
Another embodiment of the invention is shown in an unexpanded state in side view in FIG. 3. In the embodiment of FIG. 3, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30, a plurality of spiral arms 28 and a circumferential member 34. The shape of the circumferential member 34 is a 5 point star. The proximal ends 52 of the spiral arms 28 are engaged to the outer support member 30. The distal ends 50 of the spiral arms 28 may be engaged to the circumferential member 34 either at the apexes of the star shaped circumferential member 34 or between the apexes of the star shaped circumferential member 34.
Further as shown in FIG. 3, the spiral arms 28 are engaged to the circumferential member 34 at the apexes 31. In addition, the circumferential member 34 bounds a first area 58 in an unexpanded state. The first area 58 is smaller than the area bounded by the circumferential member 34 in an expanded state.
Another embodiment of the invention is shown in side view in FIG. 4. In the embodiment of FIG. 4, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. Spiral side branch section 24 includes a circumferential member 34 that is a 6 point star.
The invention is also directed to a stent having a side wall with a plurality of openings therethrough, at least one of the openings being in the form of a star-shaped opening bounded by a star shaped member. The star-shaped opening may be a star with three to nine points, as shown by way of example in FIG. 3 by a five pointed star, or a six pointed star shown in FIG. 4. Typically, there will be additional expandable structure connecting the star shaped structure to the remainder of the stent. The additional structure is configured to be expandable to form a side branch.
The stent typically will have the star shaped opening in the unexpanded state. Desirably, the stent may be expanded to form a main body and a side branch extending therefrom. The side branch may be formed by disposing a balloon catheter through the side branch terminating in the star shaped opening and inflating the balloon. Where the stent is self-expanding, the side branch structure may be allowed to self-expand.
In the embodiment of FIG. 5, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30 and a plurality of spiral arms 28. The proximal ends 52 of the spiral arms are engaged to the outer support member 30. The distal ends 50 of the spiral arms 28 are free ends.
In one or more embodiments, the invention is directed to a stent comprising a plurality of spiral arms with free ends, as shown by way of example in FIG. 5. The stent may be in an unexpanded or expanded state (not shown). In an expanded state, the free ends extend outward from a main body of the stent and form a side branch.
In the embodiment of FIG. 6, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30, a plurality of spiral arms 28 and a circumferential member 34 with a serpentine shape that has turns 36. The proximal ends 52 of the spiral arms 28 are engaged to the outer support member 30. The distal ends 50 of the spiral arms 28 are engaged to the circumferential member 34 between the turns 36. Alternatively the distal ends 50 of the spiral arms 28 may be engaged to the circumferential member 34 at the turns 36. The circumferential member 34 has first diameter 58 in an unexpanded state as measured by the distance between opposite turns. The first diameter 58 is smaller than the diameter of the circumferential member 34 in an expanded state.
The invention is also directed to a stent having a side branch section 24 with alternating ring members 34 and spiral arms 28 between the alternating ring members 34, as shown by way of example in FIGS. 7 and 14. The embodiment in FIG. 14 shows a side branch with three concentric rings 34 a,b,c and three sets of spiral arms 28 a,b,c. It is within the scope of the embodiment to have more than three concentric rings and three sets of spiral arms. In the embodiment of FIG. 7 the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30, a plurality of spiral arms 28 a, each spiral arm having a distal end 50 a and a proximal end 52 a, a circumferential member 34 a with a serpentine shape that has turns 36, a plurality of spiral arms 28 b, each spiral arm 28 b having a distal end 50 b and a proximal end 52 b, and a circumferential member 34 b with a serpentine shape that has turns 36.
The proximal ends 52 a of the spiral arms 28 a are engaged to the outer support member 30. The distal ends 50 a of the spiral arms 28 a are engaged to the turns 36 of the circumferential member 34 a. The proximal ends 52 b of the spiral arms 28 b are engaged to the circumferential member 34 a between the turns 36. The distal ends 50 b of the spiral arms 28 b are engaged to the circumferential member 34 b at the turns 36.
In the embodiment of FIG. 14, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30, a plurality of spiral arms 28 a, each spiral arm having a distal end 50 a and a proximal end 52 a, a circumferential member 34 a with a serpentine shape that has turns 36, a plurality of spiral arms 28 b, each spiral arm 28 b having a distal end and a proximal end, a circumferential member 34 b with a serpentine shape that has turns 36, a plurality of spiral arms 28 c, each spiral arm 28 c having a distal end and a proximal end.
The proximal ends 52 a of the spiral arms 28 a are engaged to the outer support member 30. The distal ends 50 a of the spiral arms 28 a are engaged to the turns 36 of the circumferential member 34 a. The proximal ends of the spiral arms 28 b are engaged to the turns 36 of the circumferential member 34 a. The distal ends of the spiral arms 28 b are engaged to the turns 36 of the circumferential member 34 b. The proximal ends of the spiral arms 28 c are engaged to the turns 36 of the circumferential member 34 b. The distal ends of the spiral arms 28 c are engaged to the turns of the circumferential member 34 c. FIG. 15 shows the embodiment of the spiral branch section in FIG. 14 in an expanded state.
In at least one embodiment, there is an intermediate ring 34 with peaks and troughs in the unexpanded state, such as is depicted in FIG. 14. The troughs are connected to the peaks of the outer ring. The peaks are connected to the inner ring. The curvature of the peaks and troughs is similar between rings.
The invention is also directed to a stent having a side branch section 24 with a plurality of interconnected spiral arms that extend in a pinwheel fashion around a center point, as shown by way of example in FIG. 16. The spiral side branch section 24 has an outer support member 30, a plurality of spiral arms 28, each spiral arm having a distal end 50 and a proximal end 52 and a plurality of connectors 38. The plurality of connectors 38 engage the proximal ends 52 of the spiral arms 28 to the outer support member 30 and the plurality of connectors 38 interconnect the spiral arms 28 at a plurality of locations. In this embodiment there are eight spiral arms 28, however there can be more than eight spiral arms 28. FIG. 17 shows the spiral side branch embodiment of FIG. 16 in an expanded state.
In the embodiment of FIG. 8 a, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30, a plurality of spiral arms 28, each spiral arm having a distal end 50 and a proximal end 52, a circumferential member 34 and a locking mechanism 42. The circumferential member 34 has a first diameter 58 in an unexpanded state. The first diameter 58 is smaller than the diameter of the circumferential member 34 in an expanded state. The locking mechanism 42 only allows the circumferential member 34 to open in one direction. An example of a suitable locking mechanism is shown by way of example in FIG. 8 b. FIG. 8 b shows a tongue 103 and groove 101 mechanism. The mechanism is shown in FIG. 8 c immediately prior to engagement.
In the embodiment of FIG. 9, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The circumferential member 34 of the spiral side branch section 24 of FIG. 8 a has a radiopaque marker 48. The radiopaque marker 48 allows a practitioner to advance the stent 20 to the bifurcation 10 and visually align the spiral side branch section 24 of the stent 20 with the branch vessel 14 using fluoroscopy or other means. The radiopaque marker 48 may be comprise any suitable radiopaque material.
The invention is also directed to a bifurcated stent having a main branch and a side branch extending from the main branch. The side branch includes a lock. The lock may be configured to lock the side branch in an expanded configuration.
The invention is also directed to a stent having a sidewall with an iris-shaped structure. Examples of such are shown in FIGS. 3-9 where the side branch section 24 forms the iris shaped structure. In some embodiments, the iris-shaped structure will be present in the unexpanded state of the stent. The iris-shaped structure will desirably be expandable outward to form a side branch having a flow path therethrough, the side branch extending outward from a main flow path of the stent. The iris-shaped structure may optionally comprise a plurality of curved members such as the spiral arms disclosed above which together form a spiral pattern about a center point. In some embodiments, the curved members will be of equal length and/or shape.
In some embodiments, the curved members will have free ends. This is shown by way of example in FIG. 5. Curved members in the form of spiral arms 28 have one free end.
In other embodiments, one end of the curved arms will extend from an outer ring-like pathway and the other end of the curved arms will extend from an inner ring. An example of such a structure is shown in FIG. 3. The inner ring structure is in the form of circumferential member 34 which is a 5 pointed star while the outer ring structure is in the form of an outer support member 30 which is in the form of a circle. Another example of such is the stent of FIG. 6. The curved arms are attached at one end to outer support member 30 in the form of a circular structure. The curved arms are attached at the other end to a first circumferential member 34 a which forms a propeller-like structure. The propeller-like structure may also be described as being a substantially circular structure with a plurality of folds extending therefrom. Stent 20 of FIG. 6 further includes a second propeller-like structure extending from the first propeller-like structure.
In the embodiment of FIGS. 10 a and 10 b, the spiral side branch section 24 of FIG. 7 is in an expanded state. The circumferential member 34 has an expanded diameter 60. When expanded, the spiral arms 28 of the side branch section 24 either can be straight as depicted in FIG. 10 a or curved as depicted in FIG. 10 b.
In the embodiment of FIG. 11, the primary branch section 22 and the spiral side branch section 24 are shown in an unexpanded state. The spiral side branch section 24 has an outer support member 30 and a plurality of spiral arms 28 d. The spiral arms 28 d have a width, length and proximal end 52. The embodiment shown in FIG. 11 has four spiral arms 28 d. The spiral arms 28 d can have any length. In this embodiment, all the spiral arms 28 d in a spiral side branch section 24 will have the same length. In at least one embodiment, all the spiral arms 28 d are not the same length. In FIG. 11, the width of the spiral arms 28 d is solid. In another embodiment as shown in FIG. 12, the interior portion of the width of the spiral arm 28 d may have an opening 39 therethrough. In FIG. 13, the spiral side branch section 24 of FIG. 11 is in an expanded state.
In yet another embodiment of the invention, a stent may be provided with a side branch support section with one or more self-expandable members extending therefrom. The self-expandable member may be in the form of a shape memory wire whose memorized shape is that of a coil. Any suitable shape memory material may be used including nitinol. The wire may be coiled when in the martensitic state and straightened and projecting outward in the austenitic state with a transition temperature at or below body temperature. The stent may be maintained in its straightened shape via a sheath. Once the one or more wires are in the bifurcated vessel, upon removal of the sheath, the one or more wires may assume the form of a coil. The wires may be welded to the main body of the stent or otherwise suitably attached thereto. It is within the scope of the invention to include only one such wire per side branch to be formed or to include two, three, four, five or more wires per side branch location.
In another embodiment of the invention, the self-expanding wires need not be attached to the main body of the stent. Rather, the one or more wires may be delivered to the desired bodily location once a primary stent, optionally balloon expandable, has been delivered to the desired bodily location. The delivery of the one or more wires to the side branch may also be simultaneous with the delivery of the primary stent. Where two wires which form coils are to be used, the wires may be arranged such that they form counter-wound helices.
Any of the inventive stents disclosed herein may have a uniform inner diameter and/or a uniform outer diameter in the unexpanded state and/or in an expanded state. The inventive stents disclosed herein may also be provided in an embodiment in which the inner and/or outer diameters are not uniform. For example, one or more portions of the stent may have a tapered outer diameter. The main body may be tapered, the side branch may be tapered or both may be tapered.
In any of the inventive stents disclosed herein, the spiral side branch section may have one or more spiral arms. The spiral side branch may be of uniform diameter when expanded or variable diameter when expanded. As an example of the latter, the spiral side branch, when expanded, may have a portion which tapers. The spiral side branch may taper from a larger diameter at the bifurcation to a smaller diameter further into the bifurcation vessel.
In many of the embodiments shown in the figures, there is no more than one spiral branch support section located in a given circumferential section of the stent. In other embodiments of the invention, additional spiral branch support sections may be located within a given circumferential segment of the stent. The inventive stents may also have multiple spiral branch support sections disposed along the length of the stent.
Also, in many of the figures, portions of the inventive stent are drawn without showing structure. It is understood that any suitable structure may be employed including, but not limited to, the cellular patterns, shown by way of example only, in U.S. Pat. Nos. 6,835,203, 6348065, and 6013091.
At least some of the embodiments disclosed herein, for example, that of FIG. 1, are advantageous in that they do not require the spiral arms to be bent back at angles in excess of 90 degrees when the side branch is expanded. Many of the prior art bifurcated stents which have petals will include petals which are bent back in excess of 90 degrees when the side branch is deployed.
At least some of the embodiments, for example, at least that of FIG. 1, are advantageous in that, for a given length of starting material (for example, a tubular blank), a longer side branch section can be made via the use of spirals.
In at least one embodiment, the invention is directed to a stent that has an expandable primary branch section and a separately expandable spiral side branch section that forms a part of the primary branch section. The expandable primary branch section is a substantially tubular body disposed about a longitudinal axis. The expandable primary branch section has a first diameter in an unexpanded state and a second diameter in an expanded state. The spiral side branch section has an unexpanded state and an expanded state. In an unexpanded state the entirety of the spiral side branch section forms a part of the surface of the substantially tubular body of the primary branch section. Thus, the spiral side branch section has the same uniform thickness as the primary branch section. The spiral side branch section has an outer support member and at least one spiral arm that curves around an opening in the spiral side branch section. The outer support member can have any shape, e.g. a shape that corresponds to the cellular design of the primary stent section, a circular shape or a serpentine shape. Each spiral arm has a proximal end and a distal end. The distal end of the spiral arm is positioned closer to the center of the opening of the spiral side branch support section than the proximal end. A non-bifurcated stent is formed when the primary branch section is in an expanded state and the spiral side branch section is in an unexpanded state. A bifurcated stent is formed when both the primary branch section and the spiral side branch section are in an expanded state.
In at least one embodiment, the spiral side branch section has only one spiral arm that expands into a coil when the spiral side branch section is in an expanded state.
In at least one embodiment, the spiral side branch section has a plurality of spiral arms. The distal ends of the spiral arms expand into a helix or multiple helices when the spiral side branch section is in an expanded state. The spiral design provides uniform support and a custom fit for tapering vessels.
In at least one embodiment, the spiral side branch section has a plurality of spiral arms and a circumferential member. The circumferential member has a first diameter in an unexpanded state and second diameter in an expanded state, the second diameter is larger than the first diameter. A plurality of spiral arms is engaged to the circumferential member. The circumferential member can be any shape. Some shapes, such as a star, can have apexes and valleys. If the shape has apexes and valleys, the spiral arms can be engaged to the circumferential member at the apexes, at the valleys, or anywhere in between. The circumferential member provides support at the distal end of the spiral side branch section.
In another embodiment the circumferential member has a serpentine shape, which has turns. In one embodiment the plurality of spiral arms are engaged to the circumferential member at the turns. In another embodiment the plurality of spiral arms are engaged to the circumferential member between the turns.
In at least one embodiment, the spiral side branch section has a plurality of circumferential members and a plurality of spiral arms. Each circumferential member can be any shape, but preferably all the circumferential members of a particular spiral side branch design have the same shape. Each circumferential member has a first diameter in an unexpanded state that is different from the first diameter of the other circumferential members, i.e. a first diameter that is either larger or smaller than the first diameter of the other circumferential members. The circumferential members are arranged so that the circumferential member with the smallest first diameter, the first circumferential member, is located closest to the center of the spiral side branch opening and the circumferential member with the largest first diameter, the nth circumferential member, is located farthest away from the center of the spiral side branch section opening. The circumferential members are engaged to neighboring circumferential members by a plurality of spiral arms.
In another embodiment there are two serpentine circumferential members and a plurality of spiral arms. Each serpentine circumferential member has a first diameter in an unexpanded state. The first diameters of the two serpentine circumferential members are different, one serpentine circumferential member having a first diameter smaller than the other serpentine circumferential member. The primary branch section can be engaged to an outer support member of the spiral side branch section. The outer support member is engaged to the proximal ends of some of the plurality of spiral arms. The distal ends of some of the plurality of spiral arms are engaged to the circumferential member with the largest first diameter at the apexes of the curved undulations. The proximal ends of some of the plurality of spiral arms are engaged to the valleys of the first circumferential member. The distal ends of the second set of spiral arms are engaged to the apexes of the curved undulations of the circumferential member with the smaller first diameter. The multiple circumferential members provide circumferential support at multiple locations of the side branch lumen while the spiral arms provide flexibility and good conformability at difficult lesion areas.
In at least one embodiment, the spiral side branch section has a circumferential member, a plurality of spiral arms and a locking mechanism. The primary stent section can be engaged to an outer support member of the spiral side branch section. The outer support member is engaged to the circumferential member by a plurality of spiral segments where at least one of the spiral arms is held in place to the circumferential member by a locking mechanism. The circumferential member can be any shape. The locking mechanism allows the rings to open in only one direction. The locking center ring provides distal support for the side branch lumen.
In at least one embodiment, the spiral side branch has at least three spiral arms. The spiral arms have a width, a length and an apex. The spiral arms may be self- expanding or balloon expandable. The length of the spiral arms can vary but preferably all the spiral arms in a spiral side branch section will have the same length. In another embodiment, there may be an opening within the width of the spiral arm.
The inventive stents may be deployed to a desired bodily location by a catheter. The inventive stent may be disposed about a catheter. If a bifurcated stent is desired, the catheter used to deliver the stent can have an elongated member that extends through the opening of the side branch section of the stent. The elongated member may be a guide wire, a catheter tube or a balloon. The catheter is used to advance the stent to the desired bodily location.
The invention is also directed to any of the inventive stents disclosed here in combination with or disposed about a delivery catheter. Optionally, the delivery catheter may include a first guide wire extending along the longitudinal flow path of the main body of the stent and a second guide wire extending out through the side branch support section.
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. Biodegradable means 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 manufactured by methods including cutting or etching a design from a tubular stock or from a flat sheet. In the latter case, the sheet may be rolled into a stent and the edges optionally joined together via welding, gluing or any other suitable technique. The stent may also be made by fabricating individual portions of the stent and then joining the portions together. For example, the main portion of the stent and the side branch portion may be separately manufactured and then joined together via welding, the use of adhesives or any other suitable technique. The stent may also be manufactured by any other suitable technique known in the art or subsequently developed.
The invention is also directed to the manufacture of the inventive stents disclosed herein. To that end, the invention is directed to a method comprising the steps of providing a tube or sheet of stent material and cutting any of the inventive stent patterns disclosed herein into the tube or sheet. In the case of a sheet, the edges of the sheet may optionally be joined together. The resulting tube with the stent pattern may then be subject to standard polishing and cleaning steps as know in the art.
The invention is also directed to treatment methods using any of the inventive stents disclosed herein. To that end, any of the inventive stents disclosed herein may be disposed about a stent delivery catheter. The catheter may be inserted in a bodily lumen and delivered to a desired bodily location, typically a region with a bifurcation. In the case of a balloon catheter, the stent may be expanded with a single balloon or with a plurality of balloons. In the former case, a blister balloon may be used to expand both the main branch of the stent as well as the side branch. In the latter case, a second balloon could be used to at least partially expand the side branch section of the stent into a bifurcation in a vessel and, optionally, yet another balloon could be used to fully expand the side branch. In some embodiments, a special guide wire may be used to initiate the side branch section into the bifurcation and a balloon then used to expand the side branch section. In the case of a self-expanding stent, a sheath or other restrain may be removed allowing the stent to self expand. In the case of hybrid stents, a balloon may be used to expand a portion of the stent and a sheath or other restrain withdraw from a portion of the stent. Subsequent to deployment of the stent, the catheter may be withdrawn from the body.
In some embodiments the stent, the delivery system or other portion of the assembly may include one or more areas, bands, coatings, members, etc. that may be detected 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. A radiopaque marker on the outer support member may facilitate placement of the stent. Optionally, a marker could be located at the spiral side branch section of the stent at a bifurcation. Similarly, a radiopaque marker on the distal end of at least one spiral arm may facilitate placement of the spiral side branch section of the stent at a bifurcation.
In some embodiments, the stent or portions thereof may include one or more mechanisms for the delivery of a therapeutic agent. In one embodiment, the side branch section may be provided with the 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 invention also includes the following embodiments as characterized in the following numbered statements:
1. In combination, a catheter and an expandable stent having a tubular surface disposed about a longitudinal flowpath, the tubular surface including at least one arm which is arranged along the surface about an opening, the opening having a first size in an unexpanded state of the stent, the at least one arm arranged to define a spiral, the expandable stent disposed about the catheter, the catheter including an elongated member which extends through the opening.
2. The combination of statement 1 wherein the elongated member comprises a guide wire.
3. The combination of statement 1 wherein the elongated member comprises a catheter tube.
4. The combination of statement 1 wherein the elongated member comprises a balloon.
5. A stent having a side wall with a plurality of openings therethrough, at least one of the openings being in the form of a star-shaped opening bounded by a star shaped member.
6. The stent of statement 5 wherein the star-shaped opening is a three pointed to a nine pointed star.
7. The stent of statement 5 wherein the star-shaped opening is a five pointed star.
8. The stent of statement 5 wherein the star-shaped opening is a six pointed star.
9. The stent of statement 5 wherein the star-shaped opening is bounded by a star shaped structure.
10. The stent of statement 5 wherein two of the openings are bounded by a star shaped member, the first star shaped member having a shorter pathway than the second star shaped member.
11. The stent of statement 5 in an expanded state, the stent having a main branch and a side branch extending therefrom.
12. A bifurcated stent formed by inserting an elongated member through the stent and inserting an elongated member through the star shaped opening, expanding the stent so as to create a side branch and a main branch.
13. A stent comprising a plurality of spiral arms with free ends.
14. The stent of statement 13 in an expanded state, the free ends extending outward from a main body of the stent and forming a side branch.
15. The stent of statement 13 having an inner diameter and an outer diameter, the inner diameter being constant along the length of the stent and the outer diameter being constant along the length of the stent.
16. The stent of statement 13 wherein the spiral arms lie flush along the surface of the stent.
17. The stent of statement 13 in an unexpanded state wherein the spiral arms spiral about a common center point.
18. A bifurcated stent having a main branch and a side branch extending from the main branch, the side branch including a lock.
19. The stent of statement 18 wherein the lock may be configured to lock the side branch in an expanded configuration.
20. A stent having a side wall with an iris-shaped structure.
21. The stent of statement 20 wherein the iris-shaped structure is present in the unexpanded state of the stent.
22. The stent of statement 21 wherein the iris-shaped structure may be expandable outward to form a bifurcated stent having a side branch.
23. The stent of statement 22 wherein the iris-shaped structure comprises a plurality of curved members which together form a spiral pattern about a center point.
24. The stent of statement 23 wherein the curved members will be of equal length and/or shape.
25. The stent of statement 23 wherein the curved members each have free ends.
26. The stent of statement 23 wherein the iris shaped structure includes an outer ring and an inner ring, the outer ring disposed about the inner ring.
27. The stent of statement 26 wherein the inner ring is star shaped.
28. The stent of statement 26 wherein the inner ring is sized to receive a balloon catheter therethrough.
29. The stent of statement 26 comprising a plurality of concentric inner rings.
30. A stent having a side wall with an outer support member with spiral members extending therefrom.
31. A stent having a side wall with a plurality of interconnected members that extend in a pinwheel fashion around a center point.
32. A stent having a side wall with alternating ring members and spiral arms.
33. A stent having a single longitudinal flowpath extending in the longitudinal direction, the stent comprising a plurality of spiral members which are configured to be expanded outward to define a second flowpath which branches outward from the longitudinal flowpath.
34. A bifurcated stent made by providing the stent of statement 33 and expanding the plurality of spiral members outward.
35. The bifurcated stent of statement 34 wherein in an unexpanded state, the spiral members are formed in a helical pattern and in an expanded state, the spiral members are straight.
36. The bifurcated stent of statement 34 wherein in an unexpanded state, the spiral members are formed in a helical pattern and in an expanded state, the spiral members are curved.
37. In combination, any of the stents of statements 4-32 and a catheter, the stent disposed about the catheter.
38. A stent delivery catheter with any of the stents of statements 4-32 disposed thereabout.
39. A stent delivery catheter with any of the stents of statements 4-32 disposed at a distal end portion of the catheter.
40. A method of manufacturing a stent comprising the steps of:
providing a tube having a sidewall;
removing material from the sidewall of tube, the remaining material of the sidewall of the tube forming a stent pattern, the remaining material including at least one spiral portion, the spiral portion including at least one spiral arm having a free end.
41. The method of statement 40 further comprising the steps of:
expanding the tube; and
expanding the spiral portion so as to form a side branch with a lumen that extends at angle from the tube.
42. A method of manufacturing a stent comprising the steps of:
providing a tube having a sidewall;
removing material from the sidewall of tube, the remaining material of the sidewall of the tube forming a stent pattern, the remaining material including at least one spiral portion and no more than one spiral portion at a given longitudinal location along the tube, the spiral portion including at least one spiral arm.
43. The method of statement 42 further comprising the steps of:
expanding the tube; and
expanding the spiral portion so as to form a side branch with a lumen that extends at angle from the tube.
44. A method of manufacturing a stent comprising the steps of:
providing a tube having a sidewall;
removing material from the sidewall of tube, the remaining material of the sidewall of the tube forming a stent pattern, the remaining material including at least one spiral portion, the spiral portion including a plurality of concentric, closed pathways each of which extends only part of the way about the longitudinal axis of the tube, the closed pathways connected one to the other via spiral arms which together form one or more spiral configurations.
45. The method of statement 44 further comprising the steps of:
expanding the tube; and
expanding the spiral portion so as to form a side branch with a lumen that extends at angle from the tube.
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.

Claims

1. An expandable stent having an exterior surface and an interior surface, an inner diameter and an outer diameter, the inner diameter being constant, there being a longitudinal flowpath through the stent, the stent comprising an expandable spiral side branch support section having a spiral configuration and disposed about a center point, the center point located at a first longitudinal coordinate and circumferential coordinate, the spiral side branch support section comprising at least one spiral arm forming a curve extending at least partially around the center point, the at least one spiral arm having a first end and a second end, the second end positioned closer to the center point than the first end, the stent having no more than one spiral branch support section disposed about a center point located at the first longitudinal coordinate.

2. The stent of claim 1, wherein the distal end of the at least one spiral arm is a free end.

3. The stent of claim 1 having only one expandable spiral side branch support section.

4. The stent of claim 3 wherein the one expandable spiral side branch support section comprises only one spiral arm.

5. The stent of claim 3 wherein the one expandable spiral side branch support section comprises a plurality of spiral arms.

6. The stent of claim 5, wherein each of the spiral arms is attached at one end to a member which forms a circumferential member extending along the exterior surface of the stent, the circumferential member extending only part of the way about the longitudinal axis of the stent.

7. The stent of claim 6 wherein the circumferential member includes at least one apex and one valley.

8. The stent of claim 7 wherein the circumferential member has a serpentine shape, the serpentine shape having turns.

9. The stent of claim 6, wherein the circumferential member has a locking mechanism.

10. The stent of claim 1 having a plurality of expandable spiral side branch sections.

11. The stent of claim 10 wherein each of at least two of the expandable spiral side branch sections comprise a plurality of spiral arms.

12. The stent of claim 1 having at least one expandable spiral side branch section which comprises a plurality of spiral arms, each of the spiral arms attached at one end to a first member which forms a first closed pathway about the center point and at another end to a second member which forms a second closed pathway about the center point, the first closed pathway being longer than the second closed pathway.

13. An expandable stent having an exterior surface and an interior surface, an inner diameter and an outer diameter, there being a longitudinal flowpath through the stent, the stent comprising an expandable spiral side branch support section which lies flush with the inner surface of the remainder of the stent, the expandable spiral side branch having a spiral configuration and disposed about a center point, the center point located at a first longitudinal coordinate and circumferential coordinate, the spiral side branch support section comprising at least one spiral arm forming a curve extending at least partially around the center point, the at least one spiral arm having a first end and a second end, the second end positioned closer to the center point than the first end, the stent having no more than one spiral branch support section disposed about a center point located at the first longitudinal coordinate.

14. The stent of claim 13 having only one expandable spiral side branch support section.

15. The stent of claim 13 wherein the one expandable spiral side branch support section comprises only one spiral arm.

16. The stent of claim 13 wherein the one expandable spiral side branch support section comprises a plurality of spiral arms.

17. A bifurcated stent formed by:

providing the expandable stent of claim 1;

expanding the stent to a first diameter expanding the at least one spiral arm outward to define a second flowpath which branches off the longitudinal flowpath.

18. The stent of claim 17 wherein at least one of the expanding steps is accomplished with a balloon.

19. The stent of claim 17 wherein at least one of the expanding steps is accomplished by withdrawing a sheath which is disposed over at least a portion of the stent.

20. In combination, a catheter and an expandable stent having a tubular surface disposed about a longitudinal flowpath, the tubular surface including at least one arm which is arranged along the surface about an opening, the opening having a first size in an unexpanded state of the stent, the at least one arm arranged to define a spiral, the expandable stent disposed about the catheter, the catheter including an elongated member which extends through the opening.