Apparatus and methods for stent manufacture
Apparatus and methods for manufacture of bifurcated stents are disclosed. The apparatus can include a base having a first mount, a second mount and a third mount. The first mount, the second mount and the third mount can be configured to secure a first mandrel, a second mandrel and a third mandrel at positions relative to one another. The mandrels may be configured to receive two or more mono-tubular stents so that the stents or components of the stents may be secured to one another to form a bifurcated stent.
1. Field of the Invention
The present inventions relates to medical devices and, more particularly, to apparatus and methods for manufacture of bifurcated stents.
2. Background of the Related Art
Stents and similar implantable medical devices, collectively referred to hereinafter as stents, are generally radially expandable endoprostheses. They are typically used to obtain and maintain the patency of the body passageway while maintaining the integrity of the passageway. Stents have provided doctors with a desirable alternative to the more invasive surgeries historically required to open obstructed passageways within the body. With the tendency being to avoid invasive surgeries, their use and range of applications has steadily increased.
Stents are typically tubular devices. That is, they comprise a body or wall that defines a lumen. Stents are frequently made of a thin-walled metallic or woven material and have a pattern of apertures, openings or holes defined around the circumference of the stent along most of its length. Typically, the pattern of apertures, openings or holes is configured to permit the stent to move from a contracted to an expanded position. Stents may be constructed from a variety of materials such as stainless steel, cobalt-chromium alloys, such as Elgiloy, nickel-titanium alloys, such as Nitinol, shape memory polymers, among other materials. The materials are typically selected for their biocompatibility among other physical characteristics that may be desirable for particular applications.
Stents are typically configured to be implanted translumenally and radially enlarged after being positioned within a lumen. They may be implanted in a variety of bodily lumens or vessels such as within the vascular system, urinary tracts, bile ducts, etc. The stent may provide a prosthetic intralumenal wall or wall support. Some stents are particularly adapted to reinforce blood vessels and to prevent restenosis following angioplasty in the vascular system. In the case of a stenosis, a stent may provide an unobstructed conduit for blood to move through the stenotic region of the vessel. In other variations, a stent may be used to treat an aneurysm by removing the pressure on a weakened part of an artery so as to reduce the risk of embolism, or of the natural artery wall bursting.
Stents may be formed in a variety of methods. In one exemplary methodology, a stent may be formed by etching or cutting the stent pattern from a tube or section of stent material. In another exemplary methodology, a sheet of stent material maybe cut or etched according to a desired stent pattern whereupon the sheet may be rolled or otherwise formed into the desired tubular or bifurcated tubular shape of the stent. In yet another exemplary methodology, one or more wires or ribbons of stent material may be braided or otherwise formed into a desired shape and pattern.
Early, stents typically shared the common design of being mono-tubular. These mono-tubular stents were suitable axial delivery and implantation within a bodily lumen. Recently, smaller stents have been utilized. These smaller stents have been inserted into coronary arteries after a coronary angioplasty procedure. Coronary angioplasty is a medical procedure used to treat blocked coronary arteries as an alternative to a coronary bypass operation. However, the need to manufacture these smaller stents has introduced a number of complications into stent manufacture one of which is the need for greater precision in the manufacturing process. In one technique, stents are cut with laser beams from small diameter tubes. As they are formed from small diameter tubes, laser cut stents manufactured from such processes have typically been mono-tubular.
Within the vasculature however, it is not uncommon for stenoses to form at any of a wide variety of vessel bifurcations. 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. Bifurcations exist within the body in a wide variety of configurations, angles, and vessel diameters. 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.
Unfortunately, mono-tubular stents are not optimal for use at a bifurcation body passageway or about a side branch of a body passageway. When implanted, mono-tubular stents can shield side branches emanating from a bodily lumen. In these cases, there is an increased risk of closure of one of the side branches or arm of the bifurcation and, at a minimum, the increased resistance to the movement of fluid through the obscured branch or arm. Thus, a need exists for bifurcated stents to support these areas. However, the manufacture of bifurcated stents can be complicated and may introduce a number of variables that are not necessarily considered when manufacturing mono-tubular stents. These complications can be exacerbated when the bifurcated stent is of a relatively small diameter. Accordingly, a need exists for apparatus and methods for manufacture of bifurcated stents.
SUMMARY OF THE INVENTIONThis Summary of the Invention capsulizes some of the claimed aspects of the present inventions. Additional details of aspects of the present inventions and/or additional embodiments of the present inventions are found in the Detailed Description of the Invention and associated Figures. Apparatus and methods in accordance with the present inventions may satisfy one or more of the needs listed in the Background of the Invention and will in certain configurations provide additional improvements and advantages that will be recognized by those skilled in the art upon review of the following Detailed Description of the Invention and associated Figures.
In one aspect, the present inventions may provide a fixture for manufacture of a bifurcated stent. The fixture may include a base having a first mount, a second mount, and a third mount. The base may define a lower surface adapted to be stably received on a work surface. A first mandrel, a second mandrel and a third mandrel may be secured to the base. The base may further define an orifice positioned about a central point and extending through the base between the lower surface and an upper surface. Alternatively to defining an orifice positioned about a central point, the base may define a cavity positioned about a central point and extending into the upper surface of the base.
The first mandrel may be secured to the first mount at one of a plurality of desired positions along the first mandrel. The first mount may define at least a first mandrel receiving passage in which the first mandrel may be secured. The first mandrel may be slidably positioned within the first mandrel receiving passage. The first mandrel receiving passage may define a first longitudinal axis. The second mandrel may be secured to the second mount at one of a plurality of desired positions along the second mandrel. The second mount may define at least a second mandrel receiving passage in which the second mandrel may be secured. The second mandrel may be slidably positioned within the second mandrel receiving passage. The second mandrel receiving passage may define a second longitudinal axis. The third mandrel may be secured to the third mount at one of a plurality of desired positions along the third mandrel. The third mount may define at least a third mandrel receiving passage in which the third mandrel may be secured. The third mandrel may be slidably positioned within the third mandrel receiving passage. The third mandrel receiving passage may define a third longitudinal axis. The first longitudinal axis, the second longitudinal axis, and the third longitudinal axis may intersect at a central point. Each of the first mandrel, the second mandrel and the third mandrel can be securable in at least one position that places the first tip of the first mandrel, the second tip of the second mandrel, and the third tip of the third mandrel adjacent to one another.
A first set screw lumen may be defined by the first mount. The first set screw lumen intersecting the first mandrel receiving passage. A first set screw may be threadably received within the first set screw lumen to secure the first mandrel relative to the base.
A second set screw lumen may be defined by the second mount. The second set screw lumen intersecting the second mandrel receiving passage. A second set screw may be threadably received within the second set screw lumen to secure the second mandrel relative to the base.
A third set screw lumen may be defined by the third mount. The third set screw lumen intersecting the third mandrel receiving passage. A third set screw may be threadably received within the third set screw lumen to secure the third mandrel relative to the base.
The first mandrel receiving passage may include a first internal thread. The first internal thread may be configured to receive including a first external thread defined on an outer surface of the first mandrel. The first external thread of the first mandrel may be threadably received within the first internal thread of the first mandrel receiving passage to permit the rotational positioning of the first mandrel within the first mandrel receiving passage. A first knob may be secured to a first outer end of the first mandrel to assist a user at gripping and/or rotating the first mandrel.
The second mandrel receiving passage may include a second internal thread. The second internal thread may be configured to receive including a second external thread defined on an outer surface of the second mandrel. The second external thread of the second mandrel may be threadably received within the second internal thread of the second mandrel receiving passage to permit the rotational positioning of the second mandrel within the second mandrel receiving passage. A second knob may be secured to a second outer end of the second mandrel to assist a user at gripping and/or rotating the second mandrel.
The third mandrel receiving passage may include a third internal thread. The third internal thread may be configured to receive including a third external thread defined on an outer surface of the third mandrel. The third external thread of the third mandrel may be threadably received within the third internal thread of the third mandrel receiving passage to permit the rotational positioning of the third mandrel within the third mandrel receiving passage. A third knob may be secured to a third outer end of the third mandrel to assist a user at gripping and/or rotating the third mandrel.
All Figures are illustrated for ease of explanation of the basic teachings of the present invention only; the extensions of the Figures with respect to number, position, relationship and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following description has been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following description has been read and understood.
Where used in various Figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “top,” “bottom,” “right,” “left,” “forward,” “rear,” “first,” “second,” “inside,” “outside,” and similar terms are used, the terms should be understood to reference only the structure shown in the drawings and utilized only to facilitate describing the illustrated embodiments. Similarly, when the terms “proximal,” “distal,” and similar positional terms are used, the terms should be understood to reference the structures shown in the drawings as they will typically be implemented by a manufacturer of stents using apparatus and methods in accordance with the present inventions.
DETAILED DESCRIPTION OF THE INVENTIONAn embodiment and components of a bifurcated stent 210 manufactured using apparatus and methods in accordance with the present inventions are generally illustrated in
As particularly illustrated in
The passages 222, 224, 226 generally extend between the proximal ends and distal ends and generally in a direction along the longitudinal axis 242, 244, 246 of the respective mono-tubular stents 212, 214, 216. The longitudinal axis 242, 244, 246 have been illustrated as relatively positioned during manufacture at 120 degree intervals about junction 30 for exemplary purposes. Those skilled in the art will recognize that a variety of relative angles distinct from those illustrated may be advantageous for various applications. Further, those skilled in the art may recognize that the mono-tubular stents 212, 214, 216 do not have to be fixed in a co-planar orientation relative to one another by the fixture 10. For example, the longitudinal axis 242 of first mono-tubular stent 212 manufactured at a 180 degree angle from the longitudinal axis 44 of the second mono-tubular stent 214. In addition, the three mono-tubular stents 212, 214, 216 are illustrated as having been manufactured in a substantially co-planar configuration. Those skilled in the art will recognize that a bifurcated stent 210 may be manufactured with a mono-tubular stent 212, for example, directed outside the plane defined by the other two mono-tubular stents 214, 216 without departing from the scope of the present inventions. Further, those skilled in the art will understand that one or more of the mono-tubular stents 212, 214, 216 may include one or more curves along its longitudinal axis which may have advantages in particular applications. Further as illustrated, the mono-tubular stents 212, 214, 216 are selected to be of generally equivalent in size and general configuration only for exemplary purposes. Those skilled in the art will recognize varying the diameter, length, cell patterns, or general configuration may have advantages in particular applications. For example, the length and diameter for each of the stents may be optimized for both deliverability of the stent and vessel coverage for particular applications.
Each of the illustrated stents 212, 214, 216 further includes one or more intraconnects 232, 234, 236 at their proximal ends for exemplary purposes. These intraconnects 232, 234, 236 may be used to interconnect the stents 212, 214, 216 into a bifurcated stent 210. Such interconnects are described in more detail in a U.S. patent application, entitled Bifurcated Stenting Apparatus and Methods and assigned Ser. No. 11/049,323 the disclosure of which is hereby incorporated by reference in its entirety. Those skilled in the art will recognize additional structures and configurations for stents or components thereof that may utilize a fixture 10 in accordance with the present inventions in their assembly into a bifurcated stent.
As particularly illustrated, each of the stents 212, 214, 216 includes a pair of intraconnects 232, 234, 236 at their proximal ends for exemplary purposes. For purposes of describing the elements and construction of the bifurcated stent 210, the term proximal shall refer to the end of the components adjacent to junction 230 and the term distal shall refer to the end opposite the proximal end of each element. The first stent 212 includes a first intraconnect 232, the second stent 214 includes a second intraconnect 234, and the third stent 216 includes a third intraconnect 236. The intraconnects 232, 234, 236 are used to weld each of the stents 212, 214, 216 relative to one another to form a bifurcated stent 210. Intraconnects 232, 234, 236 are configured to be secured at their distal ends to the proximal ends of the stents 212, 214, 216 and at their proximal ends to one another. Typically, the intraconnects 232, 234, 236 are secured to one another by laser welding as is generally illustrated throughout the figures for exemplary purposes. However, the intraconnects 232, 234, 236 may be welded using alternative methods, adhesively bonded or otherwise secured to one another using a fixture 10 in accordance with the present inventions as will be understood by those skilled in the art upon review of the present disclosure.
Fixtures 10 in accordance with the present inventions generally include a base 12 relatively securing the position of at least two mounts 20, 30, 40. A mandrel 22, 32, 42 is secured within each of the mounts 20, 30, 40. The mounts 20, 30, 40 secure the relatively position at least two mandrels 22, 32, 42 to permit components of a bifurcated stent 210 to be precisely positioned and secured relative to one another. Fixtures 10 in accordance with the present inventions may facilitate manufacture of bifurcated stent 210 by permitting the precision assembly of three independently fabricated mono-tubular stents 212, 214, 216. The manufacture of a bifurcated stent 210 from two or more mono-tubular stents 212, 214, 216 can allow for the use of conventional mono-tubular stent manufacturing techniques to provide the precursors of a bifurcated stent 210. This can reduce the need for special or complex tooling typically required for manufacture and/or assembly of bifurcated stents. Embodiments and components of embodiments of fixtures 10 and methods in accordance with the present inventions are generally illustrated in
The present inventions are generally described with reference to the figures wherein the same numbers indicate similar, identical or analogous elements in different figures and within individual figures. The elements identified in the figures may be drawn out of the proper proportions for particular applications. However, these proportions have been selected for ease of illustration and description. Further, the figures are intended to be illustrative rather than limiting and are included to facilitate the explanation of the apparatus of the present inventions not to limit the scope of the claims.
Exemplary embodiments of fixtures 10 in accordance with the present inventions are generally illustrated in
The base 12 may be modular or a unitary component. The base 12 is typically sized to be easily handled and to permit its positioning on a work surface 106 of a laser welding apparatus 100. The base 12 includes a lower surface 14 configured to stably support the base 12 when the base is positioned on a work surface 106 as shown in
The first mount 20, the second mount 30 and the third mount 40 may be integral with the base 12 or may be secured to a surface such as for example an upper surface 16 of the base 12. In one aspect, one or more of the mounts 20, 30, 40 may be formed within the base 12. In another aspect, one or more of the mounts 20, 30, 40 may extend upward from an upper surface 16 of the base 12. Mounts 20, 30, 40 may be secured to base 12 with bolts 50 or may otherwise be secured to the base such as by adhesives or welding for example as will be recognized by those skilled in the art. The base 12 may define an orifice 18 extending through the base between the lower surface 14 and the upper surface 16. Alternatively, the base may define a cavity 19 formed in the upper surface 16 of the base 12.
Each of mandrels 22, 32, 42 is generally configured to be received through a passage 222, 224, 226 in one of the mono-tubular stents 212, 214, 216. Mandrels 22, 32, 42 are typically configured in the form of rods having a generally circular cross-section although other configurations may be utilized as will be recognized by those skilled in the art. Typically, mandrels 22, 32, 42 are generally illustrated as linear however, the mandrels may have one or more curves or bends as will be recognized by those skilled in the art upon review of the present disclosure. Mandrels 22, 32, 42 are oriented such that there longitudinal axes are generally aligned with a central point 300 to permit the alignment and securing of aspects of mono-tubular stents 212, 214, 216 adjacent to one another. In one aspect, the central point 300 may be aligned with the central axis of a circular orifice 18 or cavity 19. First mandrel 22, second mandrel 32, and third mandrel 42 are typically secured to the base 12 to allow the first tip 28, second tip 38 and third tip 49 to be positioned adjacent to one another. Depending on the embodiment, tips 28, 38, 48 may be blunt, rounded or in the form of a point or edge or otherwise configured as will be recognized by those skilled in the art. In certain aspects, first mandrel 22, second mandrel 32, and third mandrel 42 may be secured to the base 12 to allow the first tip 28, second tip 38 and third tip 49 of the respective mandrels 22, 32, 42 to be abutted against one another. A first knob 62, second knob 72 and a third knob 82 may be positioned at the respective first outer end of the first mandrel 22, the second outer end of the second mandrel 32, and the third outer end of the third mandrel 42, respectively. Knobs 62, 72, 82 may include ridges or cavities to accept tools to simplify the manipulation of the mandrels 22, 32, 42 by a user.
As is generally illustrated for exemplary purposes, first mandrel 22, second mandrel 32, and third mandrel 42 may be received through a first mandrel receiving passage 66, a second mandrel receiving passage 76 and a third mandrel receiving passage 86, respectively. The first mandrel receiving passage 66, second mandrel receiving passage 76 and third mandrel receiving passage 86 can be defined in base 12 and/or by first mount 20, second mount 30 and third mount 40, respectively. Typically, the mandrel receiving passage 66, 76, 86 will fix the angular position of each of first mandrel 22, second mandrel 32, and third mandrel 42 relative to the base 12. The first mandrel 22, second mandrel 32, and third mandrel 42 may be relatively sized to slide through first mandrel receiving passage 66, second mandrel receiving passage 76 and third mandrel receiving passage 86, respectively. In one aspect, the base 12 may further define a first set screw lumen 25, a second set screw lumen 35 and a third set screw lumen 45 in communication with first mandrel receiving passage 66, second mandrel receiving passage 76 and third mandrel receiving passage 86, respectively. A first set screw 24, a second set screw 34 and a third set screw 44 may be threadably engaged within first set screw lumen 25, second set screw lumen 35 and third set screw lumen 45 to lock the first mandrel 22, second mandrel 32 and third mandrel 42 at desired positions. To lock a mandrel 22, 32, 42 at a desired position, a set screw 24, 34, 44 may be rotated relative to the base within the set screw lumen 25, 35, 45 to bias an end of the set screw 24, 34, 44 against the mandrel 22, 32, 42. In another aspect, first mandrel receiving passage 66, second mandrel receiving passage 76 and third mandrel receiving passage 86 may include first internal thread 65, second internal thread 75, and third internal thread 85, respectively. When the mandrel receiving passage 66, 76, 86 include internal thread 65, 75, 85, first mandrel 22, second mandrel 32, and third mandrel 42 may include first external thread 64, second external thread 74, and third external thread 84 respectively, to engage internal thread 65, 75, 85. When external thread 64, 74, 84 are engaged with external thread 65, 75, 85, the respective mandrel 22, 32, 42 may be longitudinally positioned relative to base 12 by rotating the mandrel 22, 32, 42.
Mandrels 22, 32, 42 are illustrated in
The embodiment of fixture 10 illustrated in
A fixture 10 in accordance with the present inventions may be used to manufacture a bifurcated stent 210 from mono-tubular stents 212, 214, 216 using a range of techniques as will be recognized by those skilled in the art upon review of the present disclosure. Generally, the each mono-tubular stent 212, 214, 216 may be made by laser cutting, water-jet cutting, or chemical etching of a preformed tube or a sheet to be rolled into a tube; by molding; by weaving; or by other methods that will be recognized by those skilled in the art. In one exemplary method, the mono-tubular stent 212, 214, 216 can be cut from a tube. In this method, the mono-tubular stent 212, 214, 216 is generally formed by removal of material from the cylindrical wall of the tube. The material remaining typically forms the mono-tubular stent 212, 214, 216. Exemplary apparatus and methods for manufacturing mono-tubular stents 212, 214, 216 in accordance with the present inventions are disclosed in U.S. Pat. Nos. 5,324,913, 5,852,277 and 6,1214,653, the disclosures of which are hereby incorporated by reference. After cutting, the cut mono-tubular stent 212, 214, 216 is typically cleaned to remove the laser scale. This cleaning may be accomplished using chemicals and methods that are known to those skilled in the art. The mono-tubular stents 212, 214, 216 may then be heat treated in an annealing process to 1850 degrees Fahrenheit followed by cooling with nitrogen to a temperature of about 100 degrees Fahrenheit before removing from the furnace. In one aspect, three mono-tubular stents 212, 214, 216 may be laser welded together. To relatively position mono-tubular stents 212, 214, 216, each of the mono-tubular stents 212, 214, 216 is fitted over a mandrel 22, 32, 42 of a fixture 10. The first tip 28, second tip 38 and third tip 38 of the respective mandrels 22, 32, 42 are then secured in a generally radial orientation about central point 300. The mono-tubular stents 212, 214, 216 are positioned on the mandrels 22, 32, 42 such that their proximal ends are positioned relative to one another in a manner to permit the laser welding of aspects of proximal ends to one another. As illustrated for exemplary purposes in
Although illustrated and described herein with reference to certain specific embodiments, the present inventions is nevertheless not intended to be limited to the details provided in the foregoing description. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention.
Claims
1. An apparatus for manufacture of a bifurcated stent, comprising:
- a base including a first mount, a second mount, and a third mount, the base defining a lower surface adapted to be stably received on a work surface,
- a first mandrel defining a first tip, the first mandrel secured to the first mount at one of a plurality of first desired positions along the first mandrel;
- a second mandrel defining a second tip, the second mandrel secured to the second mount at one of a plurality of second desired positions along the second mandrel;
- a third mandrel defining a third tip, the third mandrel secured to the third mount at one of a plurality of third desired positions along the third mandrel;
- each of the first mandrel, the second mandrel and the third mandrel being securable in at least one position that places the first tip, the second tip, and the third tip adjacent to one another.
2. An apparatus, as in claim 1, further comprising the first mount defining at least a first mandrel receiving passage, the second mount defining at least a second mandrel receiving passage and the third mount defining at least a third mandrel receiving passage, the first mandrel receiving passage defining a first longitudinal axis, the second mandrel receiving passage defining a second longitudinal axis and the third mandrel receiving passage defining a third longitudinal axis, the first mandrel slidably positioned within the first mandrel receiving passage, the second mandrel slidably received within the second mandrel receiving passage, and the third mandrel slidably received in the third mandrel receiving passage.
3. An apparatus, as in claim 2, further comprising a first set screw lumen intersecting the first mandrel receiving passage and a first set screw threadably received within the first set screw lumen to secure the first mandrel relative to the base; a second set screw lumen intersecting the second mandrel receiving passage and a second set screw threadably received within the second set screw lumen to secure the second mandrel relative to the base; and a third set screw lumen intersecting the third mandrel receiving passage and a third set screw threadably received within the third set screw lumen to secure the third mandrel relative to the base.
4. An apparatus, as in claim 2, further comprising the first longitudinal axis, the second longitudinal axis, and the third longitudinal axis intersecting at a central point.
5. An apparatus, as in claim 2, further comprising:
- the first mandrel receiving passage including a first internal thread and the first mandrel including a first external thread, the first external thread of the first mandrel threadably received within the first internal thread of the first mandrel receiving passage to permit the rotational positioning of the first mandrel within the first mandrel receiving passage;
- the second mandrel receiving passage including a second internal thread and the second mandrel including a second external thread, the second external thread of the second mandrel threadably received within the second internal thread of the second mandrel receiving passage to permit the rotational positioning of the second mandrel within the second mandrel receiving passage; and
- the third mandrel receiving passage including a third internal thread and the third mandrel including a third external thread, the third external thread of the third mandrel threadably received within the third internal thread of the third mandrel receiving passage to permit the rotational positioning of the third mandrel within the third mandrel receiving passage.
6. An apparatus, as in claim 5, further comprising a first knob secured to a first outer end of the first mandrel, a second knob secured to a second outer end of the second mandrel, and a third knob secured to a third outer end of the third mandrel.
7. An apparatus, as in claim 1, further comprising the base defining an orifice positioned about a central point and extending through the base between the lower surface and an upper surface.
8. An apparatus, as in claim 1, further comprising the base defining a cavity positioned about a central point and extending into the upper surface of the base.
Type: Application
Filed: May 17, 2006
Publication Date: Nov 22, 2007
Inventors: Gladwin S. Das (St. Paul, MN), Gary Oberg (Darwin, MN)
Application Number: 11/436,734
International Classification: B21J 13/04 (20060101);