Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS20060229714 A1
Publication typeApplication
Application numberUS 11/447,626
Publication date12 Oct 2006
Filing date6 Jun 2006
Priority date10 Mar 1995
Also published asCA2361067A1, CA2361067C, DE60030952D1, DE60030952T2, EP1148841A1, EP1148841B1, US6579314, US6740115, US7083640, US20030191519, US20040204757, WO2000045742A1, WO2000045742A9
Publication number11447626, 447626, US 2006/0229714 A1, US 2006/229714 A1, US 20060229714 A1, US 20060229714A1, US 2006229714 A1, US 2006229714A1, US-A1-20060229714, US-A1-2006229714, US2006/0229714A1, US2006/229714A1, US20060229714 A1, US20060229714A1, US2006229714 A1, US2006229714A1
InventorsSylvie Lombardi, Guido Koch, Richard Layne, Tarun Edwin, Wolfgang Supper, Walter Gamer, Thomas Kirchhoff
Original AssigneeSylvie Lombardi, Guido Koch, Richard Layne, Tarun Edwin, Wolfgang Supper, Walter Gamer, Thomas Kirchhoff
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Covered stent with encapsulated ends
US 20060229714 A1
Abstract
A covered stent including a stent covered on a first surface by a continuous covering and on a second surface by a discontinuous covering, the discontinuous covering bonded to the continuous covering, the discontinuous covering including first and second rings of material spaced apart such that a region of the second surface is uncovered.
Images(8)
Previous page
Next page
Claims(20)
1. A covered stent, comprising:
a stent formed from a tube, the stent including a plurality of rings arranged along a longitudinal axis from a first end of the stent to a second end of the stent, adjacent rings having one or more joining points;
a continuous covering positioned over a first surface of the stent from the first end of the stent to the second end of the stent; and
a discontinuous covering positioned over a second surface of the stent and bonded to the continuous covering, the discontinuous covering including first and second rings of material spaced apart such that a region of the second surface is uncovered.
2. The covered stent according to claim 1, wherein the first surface of the stent is an inner surface of the stent and the second surface of the stent is an outer surface of the stent.
3. The covered stent according to claim 1, wherein the first ring of material is adjacent the first end of the stent and the second ring of material is adjacent the second end of the stent.
4. The covered stent according to claim 1, further comprising a first extremity of the stent that defines an outer perimeter greater than an outer perimeter of the stent at any potion of the stent from the first end to the second end thereof upon expansion of the stent.
5. The covered stent according to claim 4, wherein the first extremity is not covered.
6. The covered stent according to claim 4, further comprising a second extremity of the stent that defines an outer perimeter substantially equal to the outer perimeter of the first extremity upon expansion of the stent.
7. The covered stent according to claim 6, wherein the first and second extremities are not covered.
8. The covered stent according to claim 1, further comprising a first extremity of the stent that includes a plurality of projections and recessions extending along a longitudinal axis defined by the surfaces of the stent.
9. The covered stent according to claim 8, further comprising a second extremity of the stent that includes a plurality of projections and recessions extending along a longitudinal axis defined by the surfaces of the stent.
10. The covered stent according to claim 9, wherein the projections are configured to anchor the stent within a vessel upon expansion of the stent therein.
11. The covered stent according to claim 9, wherein the first and second extremities are not covered.
12. The covered stent according to claim 1, wherein the tube comprises a shape memory material.
13. The covered stent according to claim 12, wherein the shape memory material comprises Nitinol.
14. The covered stent according to claim 1, wherein the continuous covering and the discontinuous covering comprise ePTFE.
15. The covered stent according to claim 13, wherein the discontinuous covering comprises one or more strips of ePTFE positioned over the second surface of the stent between the first ring of material and the second ring of material.
16. The covered stent according to claim 1, wherein the ring stents comprise a plurality of zigzag struts, the struts having a thickness approximately equivalent to the thickness of the tube.
17. The covered stent according to claim 16, wherein adjacent ring stents are joined by joining points spaced six struts apart.
18. The covered stent according to claim 16, wherein a given ring stent is joined to one of a first and second adjacent ring stent by a joining point every third strut, alternating between the first and second adjacent ring stents such that six struts separate the joining points between the given ring stent and the first adjacent ring stent and between the given ring stent and the second adjacent ring stent.
19. A covered stent, comprising:
a stent formed from a tube with portions removed such that when expanded, the stent includes a plurality of openings through a wall thereof;
a continuous covering positioned over a first surface of the stent from a first end of the stent to a second end of the stent; and
a discontinuous covering positioned over a second surface of the stent and bonded to the continuous covering through the plurality of openings, the discontinuous covering including strips of material arranged in a pattern such that a region of the second surface is uncovered.
20. A method of making a covered stent, comprising:
removing portions of a generally tubular structure to define a plurality of rings arranged along a longitudinal axis from a first end of the structure to a second end of the structure, adjacent rings having one or more joining points;
disposing a continuous covering over a first surface of the stent from the first end to the second end;
locating first and second rings of material over a second surface of the stent; and
bonding the first and second rings of material to the continuous covering so that a region of the second surface is not covered.
Description
    CROSS-REFERENCE TO RELATED APPLICATIONS
  • [0001]
    This application is a continuation of U.S. patent application Ser. No. 10/836,492, filed Apr. 30, 2004, which is a continuation of U.S. patent application Ser. No. 10/412,138, filed Apr. 11, 2003, now U.S. Pat. No. 6,740,115, which is a continuation of U.S. patent application Ser. No. 09/430,154, filed Oct. 29, 1999, now U.S. Pat. No. 6,579,314, which claims the benefit of U.S. Provisional Application No. 60/118,269, filed Feb. 2, 1999, and which is a continuation-in-part of U.S. patent application Ser. No. 08/401,871, filed Mar. 10, 1995, now U.S. Pat. No. 6,124,523. The entirety of each of these applications is expressly incorporated by reference as if fully set forth herein.
  • BACKGROUND OF THE INVENTION
  • [0002]
    Stents and similar endoluminal devices are currently used by medical practitioners to treat tubular body vessels or ducts that become so narrowed (stenosed) that flow of blood or other biological fluids is restricted. Such narrowing (stenosis) occurs, for example, as a result of the disease process known as arteriosclerosis. While stents are most often used to “prop open” blood vessels, they can also be used to reinforce collapsed or narrowed tubular structures in the respiratory system, the reproductive system, bile or liver ducts or any other tubular body structure. However, stents are generally mesh-like so that endothelial and other tissues can grow through the openings resulting in restenosis of the vessel.
  • [0003]
    Polytetrafluoroethylene (PTFE) has proven unusually advantageous as a material from which to fabricate blood vessel grafts or prostheses, tubular structures that can be used to replace damaged or diseased vessels. This is partially because PTFE is extremely biocompatible causing little or no immunogenic reaction when placed within the human body. This is also because in its preferred form, expanded PTFE (ePTFE), the material is light and porous and is readily colonized by living cells so that it becomes a permanent part of the body. The process of making ePTFE of vascular graft grade is well known to one of ordinary skill in the art. Suffice it to say that the critical step in this process is the expansion of PTFE into ePTFE. This expansion represents a controlled longitudinal stretching in which the PTFE is stretched to several hundred percent of its original length.
  • [0004]
    Apart from use of stents within the circulatory system, stents have proven to be useful in dealing with various types of liver disease in which the main bile duct becomes scarred or otherwise blocked by neoplastic growths, etc. Such blockage prevents or retards flow of bile into the intestine and can result in serious liver damage. Because the liver is responsible for removing toxins from the blood stream, is the primary site for the breakdown of circulating blood cells and is also the source of vital blood clotting factors, blockage of the bile duct can lead to fatal complications. A popular type of stent for use in the biliary duct has been one formed from a shape memory alloy (e.g., nitinol) partially because such stents can be reduced to a very low profile and remain flexible for insertion through the sharp bend of the bile duct while being self-expandable and capable of exerting a constant radial force to the duct wall.
  • [0005]
    Cellular infiltration through stents can be prevented by enclosing the stents with ePTFE. Early attempts to produce a stent covered by ePTFE focused around use of adhesives or physical attachment such as suturing. However, such methods are far from ideal and suturing, in particular, is very labor intensive. More recently methods have been developed for encapsulating a stent between two tubular ePTFE members whereby the ePTFE of one-member touches and bonds with the ePTFE of the other member through the mesh opening in the stent. However, such a monolithically encapsulated stent may tend to be rather inflexible. Therefore, there is a need for a stent covered to prevent cellular infiltration and yet still flexible to ensure ease of insertion and deployment and to accommodate extreme anatomical curves.
  • BRIEF SUMMARY OF THE INVENTION
  • [0006]
    The present invention is directed to covered stents wherein flexibility of the stent is retained, despite the use of encapsulation techniques. Encapsulation refers to the lamination of a stent between an inner and an outer layer of a plastic material. Compared to a fully encapsulated stent enhanced flexibility can be achieved by encapsulating limited regions of the stent, while leaving a significant portion of the stent—usually a middle portion—covered by a single layer of the plastic material. In this way the limited encapsulation fixes the plastic covering onto the stent with no need for sutures or similar labor intensive mechanical attachments.
  • [0007]
    It is an object of this invention to provide a stent device that has improved flexibility compared to a fully encapsulated stent, yet maintains its impermeability to infiltrating tissues.
  • [0008]
    It is yet another object of this invention to provide a stent device that shows minimal profile when loaded into insertion systems and can be deployed using forces that are reduced compared to those used with fully encapsulated designs.
  • [0009]
    These and additional objects are accomplished by embedding or encapsulating only portions of the stent between two layers of biocompatible material. This is accomplished by covering either the luminal or abluminal surface of the stent with a layer of biocompatible material, preferably ePTFE, while also covering limited sections of the opposite surface of the stent with the biocompatible material, thereby fully encapsulating only the limited sections. A preferred design fully encapsulates only the end regions of the device. By leaving a middle region of the stent unencapsulated, the stent is free to flex much like a bare stent, increasing overall flexibility and reducing the necessary loading and deployment forces.
  • [0010]
    In the present invention, a stent is partially encapsulated using the configuration mentioned above. One means of accomplishing this configuration is to place rings (radial strips) of ePTFE on a mandrel at positions corresponding to each end of the stent. The stent is then placed over the mandrel and the rings in registration with the ends of the stent. Finally, the stent (supported by the mandrel) is covered on its abluminal (outside) surface by a tubular ePTFE graft. The resulting structure is then subjected to heat and pressure so that the regions containing ePTFE on both surfaces become laminated or fused together (e.g., a bond is formed). This yields a stent with substantially its entire abluminal surface covered by ePTFE. Regions near the ends of the stent are fully encapsulated (e.g., these regions are covered by ePTFE on their luminal surfaces as well). The fully encapsulated area serves to attach the abluminal covering to the stent.
  • [0011]
    A more complete understanding of the partial encapsulation of stents will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings, which will first be described briefly.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0012]
    FIG. 1 is a perspective view of the preferred embodiment of the present invention.
  • [0013]
    FIG. 2 is a cross-sectional view along the line 2-2.
  • [0014]
    FIG. 3 is a cross-sectional view along the line 3-3.
  • [0015]
    FIG. 4 is an overview picture of the deployment of the device of the present invention.
  • [0016]
    FIG. 5 is a close-up view of the device being partially deployed.
  • [0017]
    FIG. 6 is a close-up view of the device fully deployed.
  • [0018]
    FIG. 7 is a picture of a fully encapsulated stent being tested for flexibility.
  • [0019]
    FIG. 8 is a picture of the covered stent of the present invention being tested for flexibility in the same manner as FIG. 7.
  • [0020]
    FIG. 9 shows an especially flexible stent design (the “Flexx” stent) preferred for use in the present invention; here the Flexx stent is shown in its expanded state.
  • [0021]
    FIG. 10 shows the flexible stent of FIG. 9 after it has been compressed.
  • [0022]
    FIG. 11 shows a close-up of the strut structure of the expanded stent of FIG. 9.
  • [0023]
    FIG. 12 shows a close-up view of the flexible stent design of FIG. 9 immediately after being cut from a metal tube and before being expanded into the form of FIG. 11.
  • DETAILED DESCRIPTION OF THE INVENTION
  • [0024]
    The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected preferred embodiments and are not intended to limit the scope of the invention.
  • [0025]
    The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.
  • [0026]
    The present invention satisfies the need for a covered stent device that is virtually as flexible as an uncovered stent. This is accomplished by covering a stent on a first surface while limited regions are covered on the opposite surface to ensure fixation of the first surface covering. Referring now to the drawings, FIG. 1 illustrates a preferred embodiment of the present invention. A partially encapsulated stent-graft 10 is created by covering the abluminal surface of a stent 12 with a biocompatible barrier material that is able to seal fistulae and aneurysms and prevent or reduce tissue ingrowth from neointimal hyperplasia or tumor growth. In the preferred embodiment, the material used for this purpose is a tubular layer of expanded polytetrafluoroethylene (ePTFE) 20. The preferred ePTFE is one optimized for bond strength as described in U.S. Pat. No. 5,749,880. The stent 12 in the preferred embodiment is a shape memory alloy stent having geometry enhancing the stent's flexibility, although stents of a variety of designs are usable with the current invention because the inventive configuration minimizes the effect of the covering on stent flexibility. Also, the stent 12 can be made out of any type of material besides shape memory alloy.
  • [0027]
    It will be apparent to those of skill in the art that at a covering over at least one of the surfaces (luminal or abluminal) of the stent is necessary to prevent tissue ingrowth. Furthermore, the covering must be bonded to the stent to prevent it from coming detached and perhaps forming a blockage in the vessel. Although ePTFE has numerous favorable properties, it is relatively difficult to attach it to a stent. Mechanical fasteners such as sutures have the disadvantage of interrupting the integrity of the ePTFE sheet so that leaking can occur. Although ePTFE does not adhere well to a stent, it can be made to bond to itself. Therefore, one effective method of affixing the ePTFE cover is to place ePTFE covers in contact with both the abluminal and luminal surfaces of the stent so that one ePTFE covering can bond to the other where the ePTFE coverings touch through the openings in the stent. The drawback with this approach is that the structural members of the stent are tightly surrounded and held by ePTFE. When the stent bends or expands, the stent structural members must move relative to each other. This movement is resisted by the tightly adhering ePTFE (or other covering material).
  • [0028]
    In the present invention movement of the stent members relative to each other is facilitated by limiting the region of the stent in which the structural members are surrounded (encapsulated) by ePTFE. In a preferred embodiment the regions of encapsulation, which ensure attachment of the covering to the stent, are limited to areas near the ends of the device. For a relatively short device these end-encapsulated regions are more than adequate to afford attachment of the covering. If necessary one or more additional regions of encapsulation could be added along the length of the device if it is found necessary for stability of the covering. Clearly, the greater the percentage of length of the device that is fully encapsulated, the more the flexibility of the overall structure will be impeded.
  • [0029]
    An additional advantage of the limited encapsulation of the present invention is the possibility of enhanced healing. It is known that living cells will infiltrate sufficiently porous ePTFE and that microcapillaries may form within and across the ePTFE wall so that a living intima is formed along the luminal surface. Where two layers of ePTFE surround the stent, it may be significantly more difficult for cellular infiltration across the wall to occur. Although the figures show the continuous covering placed on the abluminal surface of the device, the present invention also lends itself to placement of the continuous covering on the luminal surface. The configuration choice may depend on the precise application of the device. In some applications, for example large vessels having a high rate of blood flow placing the covering on the luminal surface may result in advantageous lamellar flow of the blood (ie., blood flow without significant turbulence). There is some evidence that contact of the blood with a metal stent may result in local, limited thrombosis. While this may be detrimental, there is also some evidence that such limited thrombosis results in enhanced healing. An advantage of using a full luminal covering could be improved anchoring of the device within the duct or vessel afforded by interactions between the bare abluminal stent and the duct or vessel wall. Therefore, the optimal configuration will have to be empirically determined in many cases.
  • [0030]
    In the illustrated design (FIG. 1) the extremities 14 of the stent 12 are left completely uncovered and flare outward to facilitate anchoring of the stent within the vessel following expansion of the stent in situ. It will be apparent that this flared region is a feature of this particular embodiment and is not a required element of the instant invention. The luminal surface of the stent 12 is covered at ends 22 defined between points A and B and points C and D in FIG. 1, but is left uncovered in mid-section 24 defined between points B and C. By leaving the mid-section 24 uncovered, the stent has increased flexibility as well as reduced profile when compressed. The material used to cover the ends 22 on the luminal surface of stent 12 is generally the same material that is used to cover the abluminal surface, and in FIG. 1 this material is ePTFE 30 (see FIG. 2), though any other suitable biocompatible material could be used in the present invention.
  • [0031]
    Again, it is important to note that while the continuous tubular layer of ePTFE 20 is shown on the abluminal surface of FIG. 1, it is possible, and advantageous in some cases, to place a tubular layer of ePTFE on the luminal surface, while placing limited rings of ePTFE only on the abluminal surfaces at the ends of the device. Distances A-B and C-D in FIG. 1 can be lesser or greater, depending on the need for flexibility in the particular application. Moreover, there can be any number of encapsulated region(s) and these region(s) can be located in different areas of the stent. Also, while the preferred embodiments use encapsulated regions that extend completely around a circumference of the device (e.g., rings of material) as indicated by region 32 in FIG. 1, there is no reason that discontinuous regions of encapsulation cannot be used. Attaching discrete pieces or strips of ePTFE to a mandrel before the stent is placed on the mandrel can be used to form such discontinuous regions. The size, shape and pattern formed by regions 32 can be selected to enhance flexibility, etc. This allows different regions of the device to exhibit different properties of flexibility, etc.
  • [0032]
    Once the appropriate ePTFE covering is placed onto the luminal and abluminal surfaces, the ends 22 of the stent graft 10 are encapsulated by connecting or bonding the luminal covering to the abluminal covering. Encapsulation can be accomplished by a number of methods including sintering (i.e., heating), suturing, ultrasonically welding, stapling and adhesive bonding. In the preferred embodiment, the stent-graft 10 is subjected to heat and pressure to laminate (bond) the tubular ePTFE layer 20 on the abluminal surface to the two rings of ePTFE 30 on the luminal surface.
  • [0033]
    FIGS. 2 and 3 illustrate cross-sections of FIG. 1. A cross-section of stent-graft 10 is taken along line 2-2, through an end 22 of the device 10 in FIG. 2 and along line 3-3, through the mid-section 24 in FIG. 3. These two cross-sections are shown to illustrate the additional layer of ePTFE 30 that is present on the luminal surface of the end 22 and not present on the luminal surface of the mid-section 24. As mentioned, the reason for encapsulating only the ends 22 of stent-graft 10 is to increase its flexibility over a fully encapsulated stent, thereby allowing it to be bent into extreme curves without kinking. Most of the length of the device is covered by only a single layer of ePTFE which is extremely flexible and which does not strongly interact with the stent. Therefore, the flexibility of the single layer area is essentially that of the underlying stent device. FIG. 7 shows a fully encapsulated shape memory alloy stent bent in essentially as sharp a curve as possible. Note that the covering material is showing kinks or distortions 34 due to the inability of the covering material to move longitudinally relative to the stent structural members. FIG. 8 shows an identical shape memory alloy stent covered according to the current invention: only the extreme device ends are fully encapsulated. Note that the device is capable of being bent into a much sharper curve with little or no distortion of the covering or the underlying stent.
  • [0034]
    An additional advantage provided by the present invention is that the retraction force necessary to deploy the stent-graft 10 using a coaxial deployment system is drastically reduced in comparison to a fully encapsulated stent. This is due to the reduction in amount of covering material. Furthermore, by reducing the amount of covering material, the overall profile of the deployment system is reduced, allowing a wider range of applications. Another advantage enjoyed by the present invention is its ease of manufacture compared to stent-graft devices that place multiple stent rings over ePTFE tubing. Finally, an advantage over stent-grafts with a single layer of biocompatible material over the entire graft length is that because a strong bond is created in the encapsulated region, it is possible to transmit a pulling force from one end of the stent of the present invention to the other via the covering, making it possible to load into a sheath using pulling techniques. The preferred bare stent designs (chosen for flexibility and low profile) do not permit transmission of a pulling force in a longitudinal axial direction. This is because flexibility is increased and profile reduced by removing connections between longitudinally neighboring struts. The limited number of longitudinal connections has inadequate tensile strength to transmit the pulling force without failure. In the case of a true single layer covering (without use of adhesive, etc.) pulling on the covering causes the covering to slip off the stent. In the case of sutured single layer device pulling on the covering may cause the sutures holes to enlarge and even tear.
  • EXAMPLE 1
  • [0035]
    Two memotherm (shape memory alloy stent, product of Angiomed, Division of C. R. Bard, Inc.) biliary stents (S1 and S2), partially encapsulated according to the present invention, were loaded into a 10 French delivery system used for a standard covered biliary stent. The stents were 10 mm×60 mm. The pulling force necessary to load the stents (the force between the outer sheath and the stent) was measured as follows:
      • S1=6.3N
      • S2=3.5N
  • [0038]
    In comparison, the loading force for a fully encapsulated stent is approximately 50N. After loading the samples S1 and S2 into a pullback delivery system, both were deployed into a glass biliary duct model placed in a 37° C. water bath. All deployment went smoothly and no significant covering damage was observed. Thus, the partially encapsulated stents could be loaded employing a much-reduced force without being compromised structurally.
  • EXAMPLE 2
  • [0039]
    Three prototypes (P1, P2, and P3) were built using a Gamma 2 (Flexx) design memotherm stent, 12 mm×120 mm. These prototypes were partially encapsulated according to the present invention. More particularly, the abluminal surface of each stent was covered with a tubular ePTFE material, leaving the regions near the stent ends uncovered (to flare outward and anchor the device). The luminal surface near each end of the stent was covered by a 9.95 mmą0.05 mm ring of ePTFE material. The stents were then subjected to heat and pressure so that the overlapping ePTFE material on the luminal and abluminal surfaces was bonded together. The prototypes were then loaded into a 10 French delivery system and were deployed into a glass biliary duct model (45°, 25.4 mm radius) that was placed in a 37° C. water bath.
  • [0040]
    The prototypes were loaded according to the standard loading technique used for loading fully encapsulated stents. This loading technique consists of compressing the stents by pulling them through a funnel using specially designed hooks. When loading the fully encapsulated stent, a backing mandrel and core are used to create a uniform folded pattern in the compressed stent. In loading P1, no backing mandrel and core inside the stent were used, resulting in an unacceptable load due to the presence of folds. P2 was loaded using a backing mandrel (9.2 mm diameter) and a core (1.25 mm diameter), resulting in a successful load with no folds. P3 was loaded in the same manner as P2. Loading forces between the funnel and the stent and pulling forces between the stent and the outer sheath were measured as follows:
    Prototype Peak Loading Force (N) Peak Pulling Force (N)
    P1 12.5
    P2 27.5 12.9
    P3 18.5 14.8
  • [0041]
    The loading force and pulling force necessary to load and deploy the prototypes were much smaller than that necessary for a fully encapsulated stent. Thus making it possible to load and deploy the prototypes with either a manual pullback or a pistol handgrip deployment system.
  • [0042]
    In the case of a biliary stent an especially tortuous delivery path must be used. There are two main techniques for such delivery. If the stent is deliver transhepatically, it is inserted through percutaneous vasculature, through the bulk of the liver and down the hepatic duct where it must make a bend of around 45 degrees between the hepatic and the bile duct. If the stent is delivered endoscopically it enters the bile duct via the papilla and must pass through multiple bends, the most sever of which is about 90 degrees with a 10 mm radius. Clearly an extremely flexible stent is required. To further illustrate the deployment of the prototypes, FIGS. 4-6 have been provided. FIG. 4 shows an overview of the prototypes being deployed into a glass model of a bile duct using a pistol handgrip delivery system. Note the bend that the stent must navigate. FIG. 5 shows a close-up view of a prototype, as it is partially deployed from the sheath. FIG. 6 shows a close-up view of a fully deployed prototype.
  • [0043]
    The “Flexx” stent used in these experiments is a specially designed stent configured for the present invention. Stents of this type are cut from tubes of Nitinol shape memory alloy and then expanded on a mandrel. The size memory of the device is set on the expanded form. The device is then compressed to the approximate dimensions of the original tube for insertion into a patient. Once properly located in the patient, the device is released and can self-expand to the “memorized” expanded dimension. Although the entire device is a single unitary piece, as shown in FIG. 9 in its expanded state, this design conceptually comprises a plurality of zigzag ring stents 64 (stenting zones) joined by longitudinal joining points 62.
  • [0044]
    FIG. 10 shows the recompressed device to illustrate that each ring stent 64 is attached to each adjacent ring stent 64 by only a pair of joining points 62. Note the open regions 60 between the joining points 62. It will be apparent that such a structure affords considerable lateral flexibility to the entire compressed structure. If there were a larger number of joining points 62, lateral flexibility of the compressed device would be impeded. On the other hand, the very open structure of the expanded stent (FIG. 9) offers little resistance to tissue infiltration.
  • [0045]
    These two factors account for the unusual suitability of the Flexx design in the present invention. The use of a covering of ePTFE or other biocompatible material prevents tissue infiltration despite the very open nature of the Flexx design. The use of end encapsulation (as opposed to encapsulation over the entire length of the device) preserves most of the inherent flexibility of the design. The use of only a single layer of covering over much of the stent results in a low profile in the compressed configuration so that the device can be inserted through small bile ducts and other restricted vessels. The use of only a very limited number of joining points 64 provides the lateral flexibility required for insertion through tortuous bile ducts and other similarly twisted vessels.
  • [0046]
    FIG. 11 is a close-up of a portion of FIG. 9 and shows the adjacent ring stents 64 (stenting zones) and the joining points 62. Each ring stent 64 (stenting zone) is formed from a zigzag pattern of struts 54. These struts have the thickness of the Nitinol tube from which the device is laser cut with a width, in this embodiment, of about 0.2 mm. There is a joining point 62 between a given ring stent 64 and an adjacent ring stent 64 every third strut 54 with the joining points 62 alternating from the left-hand adjacent to the right hand adjacent ring stent 64 so that six struts 54 separate the joining points 64 between any two ring stents 64. Gaps 32 replace the joining points 62 where the intersections of zigzag struts are not joined.
  • [0047]
    FIG. 12 shows a close-up of the non-expanded cut structure of FIG. 10. Cuts 40, 41, and 42 are regions where the metal has been vaporized by a computer controlled cutting laser. The cut 40 between blind cuts 41 will expand to form the window 60. Cut 42 forms the intersection point * of the struts 54, which show portions of two ring stents 64. Partially cut regions 55 define a scrap piece of metal 32′, which is removed following expansion to form the gaps 32. In the figure the partially shown region above the cut 40 and above the scrap piece 32′ is the joining point 62. Because a structure with only two joining pieces 62 between adjacent stent rings 64 is too fragile to withstand expansion as from FIG. 12 to FIG. 11, the scrap pieces 32′ act as reinforcing joining points for the radial expansion process. Following expansion the scrap pieces 32′ are removed to form the gaps 32. This structure can then be deformed into the reduced diameter flexible structure shown in FIG. 10. It will be apparent that although this structure is described and pictured as having circumferential ring stents 64, the stents zones can also be arranged in a helical manner to achieve the objects of the improved design.
  • [0048]
    Having thus described a preferred embodiment of the covered stent with encapsulated ends, it will be apparent by those skilled in the art how certain advantages of the present invention have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made. For example, while Flexx stent designs partially covered with ePTFE have been illustrated, it should be apparent that the inventive concepts described herein would be equally applicable to other types of stent designs and biocompatible covering materials. Moreover, the words used in this specification to describe the invention and its various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification structure, material or acts beyond the scope of the commonly defined meanings. The definitions of the words or elements of the following claims are, therefore, defined in this specification to include not only the combination of elements which are literally set forth, but all equivalent structure, material or acts for performing substantially the same function in substantially the same way to obtain substantially the same result. The described embodiments are to be considered illustrative rather than restrictive. The invention is further defined by the following claims.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4324574 *19 Dec 198013 Apr 1982E. I. Du Pont De Nemours And CompanyFelt-like layered composite of PTFE and glass paper
US4647416 *26 Apr 19853 Mar 1987Shiley IncorporatedMethod of preparing a vascular graft prosthesis
US5078736 *4 May 19907 Jan 1992Interventional Thermodynamics, Inc.Method and apparatus for maintaining patency in the body passages
US5122154 *15 Aug 199016 Jun 1992Rhodes Valentine JEndovascular bypass graft
US5123917 *27 Apr 199023 Jun 1992Lee Peter YExpandable intraluminal vascular graft
US5133732 *22 Mar 198928 Jul 1992Medtronic, Inc.Intravascular stent
US5135503 *16 May 19904 Aug 1992Advanced Cardiovascular Systems, Inc.Shaping ribbon for guiding members
US5139480 *22 Aug 199018 Aug 1992Biotech Laboratories, Inc.Necking stents
US5211658 *5 Nov 199118 May 1993New England Deaconess Hospital CorporationMethod and device for performing endovascular repair of aneurysms
US5234456 *7 May 199210 Aug 1993Pfizer Hospital Products Group, Inc.Hydrophilic stent
US5236447 *28 Jun 199117 Aug 1993Nissho CorporationArtificial tubular organ
US5282823 *19 Mar 19921 Feb 1994Medtronic, Inc.Intravascular radially expandable stent
US5282849 *19 Dec 19911 Feb 1994University Of Utah Research FoundationVentricle assist device with volume displacement chamber
US5330500 *17 Oct 199119 Jul 1994Song Ho YSelf-expanding endovascular stent with silicone coating
US5383928 *19 Aug 199324 Jan 1995Emory UniversityStent sheath for local drug delivery
US5384019 *29 Oct 199324 Jan 1995E. I. Du Pont De Nemours And CompanyMembrane reinforced with modified leno weave fabric
US5389106 *29 Oct 199314 Feb 1995Numed, Inc.Impermeable expandable intravascular stent
US5395390 *16 Dec 19937 Mar 1995The Beth Israel Hospital AssociationMetal wire stent
US5405378 *20 May 199211 Apr 1995Strecker; Ernst P.Device with a prosthesis implantable in the body of a patient
US5421955 *17 Mar 19946 Jun 1995Advanced Cardiovascular Systems, Inc.Expandable stents and method for making same
US5437083 *24 May 19931 Aug 1995Advanced Cardiovascular Systems, Inc.Stent-loading mechanism
US5443496 *15 Oct 199322 Aug 1995Medtronic, Inc.Intravascular radially expandable stent
US5507767 *15 Jan 199216 Apr 1996Cook IncorporatedSpiral stent
US5507768 *6 Jul 199316 Apr 1996Advanced Cardiovascular Systems, Inc.Stent delivery system
US5507769 *18 Oct 199416 Apr 1996Stentco, Inc.Method and apparatus for forming an endoluminal bifurcated graft
US5514154 *28 Jul 19947 May 1996Advanced Cardiovascular Systems, Inc.Expandable stents
US5522881 *28 Jun 19944 Jun 1996Meadox Medicals, Inc.Implantable tubular prosthesis having integral cuffs
US5522883 *17 Feb 19954 Jun 1996Meadox Medicals, Inc.Endoprosthesis stent/graft deployment system
US5523092 *28 Jan 19944 Jun 1996Emory UniversityDevice for local drug delivery and methods for using the same
US5527353 *2 Dec 199318 Jun 1996Meadox Medicals, Inc.Implantable tubular prosthesis
US5527355 *2 Sep 199418 Jun 1996Ahn; Sam S.Apparatus and method for performing aneurysm repair
US5546646 *17 Feb 199520 Aug 1996Advanced Cardiovascular Systems, Inc.Method for mounting an intravascular stent on a catheter
US5549635 *3 Apr 199527 Aug 1996Solar, Rita & Gaterud, Ltd.Non-deformable self-expanding parallel flow endovascular stent and deployment apparatus therefore
US5549663 *9 Mar 199427 Aug 1996Cordis CorporationEndoprosthesis having graft member and exposed welded end junctions, method and procedure
US5591223 *23 Jun 19947 Jan 1997Children's Medical Center CorporationRe-expandable endoprosthesis
US5593417 *27 Nov 199514 Jan 1997Rhodes; Valentine J.Intravascular stent with secure mounting means
US5603721 *13 Nov 199518 Feb 1997Advanced Cardiovascular Systems, Inc.Expandable stents and method for making same
US5632840 *6 Jun 199527 May 1997Advanced Cardiovascular System, Inc.Method of making metal reinforced polymer stent
US5639278 *13 Nov 199517 Jun 1997Corvita CorporationExpandable supportive bifurcated endoluminal grafts
US5645559 *21 Dec 19938 Jul 1997Schneider (Usa) IncMultiple layer stent
US5649950 *1 May 199522 Jul 1997C. R. BardSystem for the percutaneous transluminal front-end loading delivery and retrieval of a prosthetic occluder
US5649977 *22 Sep 199422 Jul 1997Advanced Cardiovascular Systems, Inc.Metal reinforced polymer stent
US5653727 *18 Jan 19965 Aug 1997Medtronic, Inc.Intravascular stent
US5653747 *20 Oct 19955 Aug 1997Corvita CorporationLuminal graft endoprostheses and manufacture thereof
US5713949 *6 Aug 19963 Feb 1998Jayaraman; SwaminathanMicroporous covered stents and method of coating
US5718159 *30 Apr 199617 Feb 1998Schneider (Usa) Inc.Process for manufacturing three-dimensional braided covered stent
US5718973 *26 Jul 199517 Feb 1998W. L. Gore & Associates, Inc.Tubular intraluminal graft
US5723003 *16 Jan 19963 Mar 1998Ultrasonic Sensing And Monitoring SystemsExpandable graft assembly and method of use
US5723004 *31 Jan 19963 Mar 1998Corvita CorporationExpandable supportive endoluminal grafts
US5728131 *12 Jun 199517 Mar 1998Endotex Interventional Systems, Inc.Coupling device and method of use
US5728158 *14 Jan 199717 Mar 1998Advanced Cardiovascular Systems, Inc.Expandable stents
US5735892 *18 Aug 19937 Apr 1998W. L. Gore & Associates, Inc.Intraluminal stent graft
US5735893 *14 Jan 19977 Apr 1998Advanced Cardiovascular Systems, Inc.Expandable stents and method for making same
US5738674 *17 Jul 199614 Apr 1998Advanced Cardiovascular Systems, Inc.Stent loading mechanism
US5749880 *27 Jul 199512 May 1998Impra, Inc.Endoluminal encapsulated stent and methods of manufacture and endoluminal delivery
US5755770 *31 Jan 199526 May 1998Boston Scientific CorporatiionEndovascular aortic graft
US5755774 *22 Aug 199626 May 1998Corvita CorporationBistable luminal graft endoprosthesis
US5755781 *13 Feb 199726 May 1998Iowa-India Investments Company LimitedEmbodiments of multiple interconnected stents
US5766238 *24 Mar 199716 Jun 1998Advanced Cardiovascular Systems, Inc.Expandable stents and method for making same
US5769817 *28 Feb 199723 Jun 1998Schneider (Usa) Inc.Coextruded balloon and method of making same
US5769884 *27 Jun 199623 Jun 1998Cordis CorporationControlled porosity endovascular implant
US5776161 *16 Oct 19957 Jul 1998Instent, Inc.Medical stents, apparatus and method for making same
US5782904 *29 Sep 199421 Jul 1998Endogad Research Pty LimitedIntraluminal graft
US5788626 *18 Nov 19964 Aug 1998Schneider (Usa) IncMethod of making a stent-graft covered with expanded polytetrafluoroethylene
US5873906 *21 Jul 199723 Feb 1999Gore Enterprise Holdings, Inc.Procedures for introducing stents and stent-grafts
US5876448 *13 Mar 19962 Mar 1999Schneider (Usa) Inc.Esophageal stent
US5925061 *13 Jan 199720 Jul 1999Gore Enterprise Holdings, Inc.Low profile vascular stent
US5928279 *3 Jul 199627 Jul 1999Baxter International Inc.Stented, radially expandable, tubular PTFE grafts
US6015431 *23 Dec 199618 Jan 2000Prograft Medical, Inc.Endolumenal stent-graft with leak-resistant seal
US6036724 *16 Jan 199814 Mar 2000Meadox Medicals, Inc.PTFE vascular graft and method of manufacture
US6042605 *18 Jul 199728 Mar 2000Gore Enterprose Holdings, Inc.Kink resistant stent-graft
US6048484 *1 Nov 199611 Apr 2000W. L. Gore & Associates, Inc.Process for forming a seamless tube of expanded PTFE from a sheet of expanded PTFE
US6375787 *22 Apr 199623 Apr 2002Schneider (Europe) AgMethods for applying a covering layer to a stent
US6379379 *13 Aug 199930 Apr 2002Scimed Life Systems, Inc.Stent with smooth ends
US6383214 *21 Mar 20007 May 2002Impra, Inc., A Subsidiary Of C. R. Bard, Inc.Encapsulated stent
US6398803 *2 Sep 19994 Jun 2002Impra, Inc., A Subsidiary Of C.R. Bard, Inc.Partial encapsulation of stents
US6524334 *21 Apr 200025 Feb 2003Schneider (Usa)Expandable stent-graft covered with expanded polytetrafluoroethylene
US6579314 *29 Oct 199917 Jun 2003C.R. Bard, Inc.Covered stent with encapsulated ends
US6673103 *16 May 20006 Jan 2004Scimed Life Systems, Inc.Mesh and stent for increased flexibility
US6673105 *2 Apr 20016 Jan 2004Advanced Cardiovascular Systems, Inc.Metal prosthesis coated with expandable ePTFE
US6733524 *5 Feb 200211 May 2004Scimed Life Systems, Inc.Polymer coated stent
US6740115 *11 Apr 200325 May 2004C. R. Bard, Inc.Covered stent with encapsulated ends
US6758858 *24 Oct 20016 Jul 2004Bard Peripheral Vascular, Inc.Diametrically adaptable encapsulated stent and methods for deployment thereof
US6770086 *2 Nov 20003 Aug 2004Scimed Life Systems, Inc.Stent covering formed of porous polytetraflouroethylene
US20010010012 *16 Jan 200126 Jul 2001Impra, Inc., A Subsidiary Of C.R. Bard, Inc.Selective adherence of stent-graft coverings, mandrel and method of making stent-graft device
US20020040237 *21 Sep 20014 Apr 2002Meadox Medicals, Inc.ePTFE graft-stent composite device
US20030004559 *5 Aug 20022 Jan 2003Scimed Life Systems, Inc.PTFE vascular graft and method of manufacture
US20030006528 *12 Sep 20029 Jan 2003Edwin Tarun J.Methods for making encapsulated stent-grafts
US20030144725 *13 Feb 200131 Jul 2003Sylvie LombardiStent matrix
US20040024442 *25 Jun 20025 Feb 2004Scimed Life Systems, Inc.Elastomerically impregnated ePTFE to enhance stretch and recovery properties for vascular grafts and coverings
US20040162603 *19 Nov 200319 Aug 2004Scimed Life Systems, Inc.Mesh graft and stent for increased flexibility
US20040162604 *11 Feb 200419 Aug 2004Boston Scientific Corp./ Scimed Life Systems, Inc.ePTFE graft with axial elongation properties
US20050055081 *22 Oct 200410 Mar 2005Atrium Medical CorpotationCovered stent and method of covering a stent
US20050060020 *17 Sep 200317 Mar 2005Scimed Life Systems, Inc.Covered stent with biologically active material
US20050096737 *10 Dec 20045 May 2005Donald ShannonRadially-expandable PTFE tape-reinforced vascular grafts
US20050113909 *26 Aug 200426 May 2005Shannon Donald T.Polymer coated stents
US20050131515 *16 Dec 200316 Jun 2005Cully Edward H.Removable stent-graft
US20050131527 *7 Dec 200416 Jun 2005Pathak Chandrashekhar P.Implantable medical devices with fluorinated polymer coatings, and methods of coating thereof
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US833765029 Mar 201225 Dec 2012Bard Peripheral Vascular, Inc.Methods for making a supported graft
US841463522 May 20089 Apr 2013Idev Technologies, Inc.Plain woven stents
US841978813 Jul 201216 Apr 2013Idev Technologies, Inc.Secured strand end devices
US86173378 Feb 201131 Dec 2013Bard Peripheral Vascular, Inc.Partial encapsulation of stents
US861744117 Feb 201231 Dec 2013Bard Peripheral Vascular, Inc.Methods for making an encapsulated stent
US864745814 Dec 201211 Feb 2014Bard Peripheral Vascular, Inc.Methods for making a supported graft
US873938213 Jul 20123 Jun 2014Idev Technologies, Inc.Secured strand end devices
US887688013 Jul 20124 Nov 2014Board Of Regents, The University Of Texas SystemPlain woven stents
US887688122 Oct 20074 Nov 2014Idev Technologies, Inc.Devices for stent advancement
US896673328 May 20143 Mar 2015Idev Technologies, Inc.Secured strand end devices
US897451617 Dec 201310 Mar 2015Board Of Regents, The University Of Texas SystemPlain woven stents
US902309527 May 20115 May 2015Idev Technologies, Inc.Stent delivery system with pusher assembly
US914937423 Apr 20146 Oct 2015Idev Technologies, Inc.Methods for manufacturing secured strand end devices
US93581407 Dec 20147 Jun 2016Aneuclose LlcStent with outer member to embolize an aneurysm
US940872920 Jan 20159 Aug 2016Idev Technologies, Inc.Secured strand end devices
US940873019 Jan 20169 Aug 2016Idev Technologies, Inc.Secured strand end devices
US95857765 Aug 20167 Mar 2017Idev Technologies, Inc.Secured strand end devices
US962973621 Oct 201625 Apr 2017Idev Technologies, Inc.Secured strand end devices
CN105997298A *28 Jun 201612 Oct 2016黄连军Aortic stent
Classifications
U.S. Classification623/1.44
International ClassificationA61L31/04, A61L31/00, A61F2/84, A61F2/06
Cooperative ClassificationA61F2/07, A61F2/848, A61F2230/0054, A61F2002/075, A61L31/048, A61F2230/005, A61F2002/072, A61F2/89, A61F2/915
European ClassificationA61F2/07, A61L31/04H