Intraluminal graft assembly and vessel repair system

FIELD OF THE INVENTION

[0001] The present invention relates generally to radially self-expanding support frames for intraluminal therapeutic use. More particularly, the present invention relates to an intraluminal support frame having a graft material disposed on its surface.

BACKGROUND OF THE INVENTION

[0002] Various types of disease conditions present clinical situations in which a vessel of a patient needs to be artificially supported or held in an open position. For example, blood flow through an artery can be impeded due to a build-up of cholesterol. Also, walls of a vessel may be weakened by an aneurysm.

[0003] Intraluminal support frames, sometimes referred to as stents, provide an artificial mechanism to support a body vessel. Generally, these support frames are tubular structures formed in a mesh pattern of metal, plastic, or other suitable material. Self-expanding support frames are able to take on a radially compressed configuration, which facilitates delivery of the frame to the site of interest. Once at the site, the force holding the frame in the radially compressed configuration is removed, and the frame takes on its radially expanded configuration. In this configuration, the frame exerts radially outward force on the vessel, which supports the vessel.

[0004] As indicated above, the support frame is typically made of a metal or other suitable material in a mesh-like pattern. While the mesh structure allows for the radial expansion, it concentrates the outward force exerted on the vessel to the individual threads forming the mesh. Little or no force is exerted on the vessel walls in the voids or empty spaces in the mesh structure. As a result, tissue ingrowth can occur in the voids, which may lead to restenosis of the vessel and may necessitate additional treatment for the patient, which might include replacement of the stent.

[0005] Several devices have been proposed that combine a graft material with a support frame. The use of a graft provides a continuous surface for supporting the vessel and operates to minimize the ingrowth problem mentioned above.

[0006] When compressed, a typical support frame often has a greater length than when it is in its radially expanded configuration. This, in the past, has forced the use of graft materials that can change dimensions along with the support frame. As a result, grafts made of woven and other elastic materials populate the prior art. This placed constraints on the types of graft material that could be utilized. Furthermore, the stretching of the graft material presents an opportunity for kinking, overstretching, and even tearing of the graft.

[0007] In view of these and other deficiencies of the prior art, there is a need for an intraluminal graft assembly that allows the support frame to radially expand independently of the graft material.

SUMMARY OF THE INVENTION

[0008] The present invention provides an intraluminal graft assembly that includes a radially self-expanding support frame of a tubular shape and a graft disposed on the frame. One or more connectors are disposed on a first end of the support frame and attach the graft to the frame. The graft is free from, i.e., not connected to, the second end of the support frame.

[0009] The graft extends along a fractional length of the length of the support frame when the frame is in its radially compressed configuration. This allows the graft to extend substantially along the entire length of the support frame when the frame is in its shorter, radially expanded configuration.

[0010] The connectors can take various forms. Preferably, the connectors comprise a barb or loop structure formed from a thread of the frame. The connector can pass through an opening in the graft, or can otherwise be attached to the graft, such as by sutures.

[0011] In one embodiment, the graft assembly comprises a radially self-expanding support frame comprising a tubular structure formed of one or more frame threads and having a first end, a second end, a radially compressed configuration with a first length and a first diameter, and a radially expanded configuration with a second length that is shorter than the first length and a second diameter that is larger than the first diameter; at least one connector on the first end of the support frame; and a graft disposed on the support frame and attached to the first end by the connector. The graft extends along a fractional length of the first length of the support frame when the frame is in the radially compressed configuration. Also, the graft is free of the second end of the support frame.

[0012] The present invention also provides a system for repairing a vessel of a patient. In one embodiment, the system comprises a graft assembly according to the present invention and a deployment device that includes first and second coaxial sleeves. The second sleeve is disposed within an interior lumen of the first sleeve, creating an annular space between the sleeves. The support frame is substantially disposed in an interior lumen of the second sleeve and the graft is substantially disposed in the annular space between the first and second sleeves. The first end of the support frame, which is attached to the graft via one or more connectors, extends beyond the first and second sleeves. A driving member is disposed in the lumen of the second sleeve.

[0013] The present invention also provides a method of placing a graft on a support frame. One embodiment according to the invention comprises providing a system for repairing a vessel of a patient according to the invention and manipulating the driving member of the system such that the driving member forces the support frame out of the lumen of the second sleeve, and the graft out of the annular space. While exiting the second sleeve at the repair site, the support frame adopts its radially expanded configuration.

[0014] The invention is defined in the appended claims. Additional understanding of the invention can be achieved by reference to the following figures and detailed description of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view, partially broken away, of an intraluminal graft assembly according to a first preferred embodiment of the present invention. The support frame of the assembly is in a radially expanded configuration.

[0016]FIG. 2 is a partial cross-sectional view of the assembly of FIG. 1. The support frame of the assembly is in a radially compressed configuration.

[0017]FIG. 3 is a perspective view, partially broken away, of an intraluminal graft assembly according to a second preferred embodiment of the present invention. The support frame of the assembly is in a radially expanded configuration.

[0018]FIG. 4A is a perspective view, partially broken away, of a vessel repair system according to the present invention.

[0019]FIG. 4B is a magnified cross-sectional view of the graft assembly stored in the repair system of FIG. 4A.

[0020]FIG. 5A is a magnified view of the distal end of the repair system illustrated in FIG. 4.

[0021]FIG. 5B is a cross-sectional view of the graft assembly of FIG. 5A in a partially expanded configuration.

[0022]FIG. 6 is a cross-sectional view of the graft assembly partially deployed in the lumen of a vessel in a patient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0023] The following description of preferred embodiments of the invention provides examples of the present invention. The embodiments discussed herein are merely exemplary in nature, and are not intended to limit the scope of the invention in any manner. Rather, the description of these preferred embodiments serves to enable a person of ordinary skill in the relevant art to make and use the present invention.

[0024]FIG. 1 illustrates an intraluminal graft assembly <b>10</b> according to a preferred embodiment of the invention. The graft assembly <b>10</b> includes a support frame <b>12</b>, one or more connectors <b>14</b>, and a graft <b>16</b>.

[0025] A variety of stent types can be used as the support frame. For example, both self-expanding and balloon-expandable stents can be used. Preferably, the support frame <b>12</b> is a radially self-expanding support frame formed into a tubular structure. The support frame <b>12</b> is able to take on at least two configurations: a radially compressed configuration and a radially expanded configuration. FIG. 1 illustrates the support frame <b>12</b> in the radially expanded configuration. The support frame <b>12</b> takes on the radially compressed configuration when a constraining force is applied around the frame <b>12</b>, such as when the frame is stored in a delivery device for later deployment. FIG. 2 illustrates the graft assembly <b>10</b> of FIG. 1 with the support frame <b>12</b> in the radially compressed configuration. In this configuration, the support frame <b>12</b> has a diameter that is smaller than the diameter of the frame <b>12</b> when in the radially expanded configuration (illustrated in FIG. 1). Also, the support frame <b>12</b> has a length that is greater than the length of the frame <b>12</b> when it is in the radially expanded configuration (illustrated in FIG. 1).

[0026] The support frame <b>12</b> is formed of one or more frame threads <b>18</b>. As the support frame can be formed from a variety of materials and methods, the threads can have various configurations. For example, the threads can comprise wires or material left in a form after an etching or cutting process. As illustrated in FIG. 1, the threads <b>18</b> are preferably wire-like structures formed of the material chosen for the support frame <b>12</b>. The threads <b>18</b> are repeatedly wound together (or upon itself if a single thread is chosen) to form a plurality of intersections <b>20</b> and open cells <b>22</b>. Preferably, as best illustrated in FIG. 1, the intersections <b>20</b> comprise simple weave overlaps between threads or portions thereof. Because of the overlap structure, the support frame <b>12</b> remains flexible by allowing the cells <b>22</b> to change in size and configuration as the frame <b>12</b> is manipulated, such as when the frame <b>12</b> changes from a radially compressed configuration to a radially expanded configuration.

[0027] The frame threads <b>18</b> can be woven together in any suitable pattern. The weaving pattern illustrated in FIG. 1 merely represents a preferred pattern for use in the present invention. A wide variety of weaving patterns are known to those skilled in the art, and any suitable pattern can be used. The pattern chosen need only allow for the use of connectors <b>14</b> to attach the graft <b>16</b> to the frame <b>12</b>, as described below. Examples of other suitable patterns include simple three thread tubular braids (two-dimensional braid) and a three-dimensional braid. The support frame <b>12</b> can be fabricated from the frame threads <b>18</b> by using various industrial weaving techniques known in the art.

[0028] The support frame <b>12</b>, and therefore the frame threads <b>18</b>, can be formed from a wide variety of materials. The material chosen should allow the support frame <b>12</b> to radially expand and should also be medically acceptable (e.g., biocompatible). Accordingly, the support frame <b>12</b> can be formed of a wide variety of natural and synthetic materials including collagen, various thermoplastics, and various metals. Examples of suitable thermoplastics include polyesters, polypropylenes, polyethylenes, polyurethanes, polytetrafluoroethylenes (PTFEs), and combinations and mixtures thereof. Examples of suitable metals include stainless steel, titanium, nickel-chromium alloys, and nickel-titanium alloys. Preferred materials include stainless steel and nickel-titanium alloys known to those skilled in the art.

[0029] Particularly preferred materials include materials that allow the support frame to radially self-expand, such as various shape memory materials. In this embodiment, the shape memory properties allow the frame <b>12</b> to return to a predetermined configuration when a particular temperature is encountered. Shape memory materials, such as various nickel-titanium alloys and their operation are known to those skilled in the art and will not be described in detail herein.

[0030] At least one connector <b>14</b> is disposed on a first end of the support frame <b>12</b>. The connector <b>14</b> is a structural member capable of retaining the graft <b>16</b> adjacent the first end of the support frame <b>12</b>. That is, the connector <b>14</b> is a structural member capable of attaching the graft <b>16</b> to the first end of the support frame <b>12</b>.

[0031] The size, shape and configuration of the connector <b>14</b> can vary. The connector <b>14</b> need only be able to interact with the graft <b>16</b> in a manner that accomplishes the desired attachment between the graft <b>16</b> and the first end of the support frame <b>12</b>. Preferably, the connector <b>14</b> is integrally formed by one or more frame threads <b>18</b>. For example, as illustrated in FIG. 1, the connector <b>14</b> can comprise a barb formed from the terminal ends of two frame threads <b>18</b> that have been twisted together. In this embodiment, the connector preferably includes a tapered point <b>24</b> at its end. The point <b>24</b> facilitates placement of the graft <b>16</b> over the connector <b>14</b> during fabrication of the graft assembly <b>10</b>. The point <b>24</b> need not be sharp enough to be able to pierce the graft <b>16</b>. Rather, the point <b>24</b> need only have a pointed shape that facilitates navigation of the connector <b>14</b> through a structure, such as an aperture <b>26</b> in the graft <b>16</b>.

[0032]FIG. 3 illustrates a second preferred embodiment of the graft assembly <b>110</b> of the present invention. This embodiment is identical to the first preferred embodiment, except as described below. Accordingly, reference numbers in FIG. 3 refer to similar features and/or components of the embodiment illustrated in FIG. 1, and differ from those in FIG. 1 by 100.

[0033] In this second embodiment, the connector <b>114</b> comprises a loop structure formed by a frame thread <b>118</b> and a suture <b>150</b>. The suture <b>150</b> passes through the graft <b>116</b> and around a portion of the loop structure to achieve the desired attachment between the connector <b>114</b> and the graft <b>116</b>.

[0034] As illustrated in both FIGS. 1 and 3, the connector <b>14</b>, <b>114</b> preferably extends away from the second end of the support frame <b>12</b>, <b>112</b> (i.e., the end opposite the end on which the connector <b>14</b>,<b>114</b> is disposed). As will be described in more detail below, the graft assembly is pushed out of a repair system by a driving member. This arrangement of the connector <b>14</b>,<b>114</b> helps to assure that the graft <b>16</b>, <b>116</b> moves with the frame <b>12</b>, <b>112</b> when the frame <b>12</b>, <b>112</b> is pushed out of a deployment device, such as that described below. Also, as illustrated in both FIGS. 1 and 3, the graft assembly preferably includes a plurality of connectors <b>14</b>, <b>114</b> disposed around the circumference of the first end of the support frame <b>12</b>,<b>112</b>.

[0035] A variety of other structures for attaching the graft to the support frame can be used as the connector. For example, the connector can be formed into a loop structure that pierces through the graft, the connector can be formed into a clip structure that frictionally engages an edge of the graft, or the connector can be formed into a rivet-like structure that fits through a hole in the graft and retains the graft adjacent the frame.

[0036] Referring to FIG. 1, the graft <b>16</b>, as indicated above, is attached to the first end of the support frame by the connector <b>14</b>. The graft <b>16</b> is free of the second end of the support frame <b>12</b>. That is, the graft <b>16</b> is not attached to the second end of the support frame <b>12</b>, even though the graft <b>16</b> lies adjacent to this end of the frame <b>12</b>. This arrangement allows for partial separation of the graft <b>16</b> and support frame <b>12</b> when the assembly <b>10</b> is placed in a repair system, as will be described below.

[0037] As illustrated in FIG. 1, the graft <b>16</b> preferably extends substantially along the entire length of the support frame <b>12</b> when the frame <b>12</b> is in the radially expanded configuration. This allows the graft <b>16</b> to cover the frame threads <b>18</b>, intersections <b>20</b>, and open cells <b>22</b> when the graft assembly <b>10</b> is deployed within a body vessel in the radially expanded configuration. As illustrated in FIG. 2, the graft <b>16</b> extends along only a fractional length of the support frame <b>12</b> when the frame <b>12</b> is in the radially compressed state, such as when the assembly <b>10</b> is stored in a repair system for later deployment. As used herein, the term “fractional length” refers to a length along the support frame <b>12</b> that is less than the total length of the support frame <b>12</b> in the radially compressed configuration. The actual fractional length used will depend on several factors, including any or all of the length of the support frame <b>12</b> in the radially compressed configuration, the length of the support frame <b>12</b> in the radially expanded configuration, and the inner diameter of the vessel in which the assembly will be deployed, which indicates the percentage of the frame diameter of the radially expanded configuration that can be attained in that particular vessel. Accordingly, the fractional length utilized can be optimized based on these and other parameters. Examples of preferred fractional lengths include ¼, ½, and ¾ of the length of the support frame <b>12</b> when in the radially compressed configuration.

[0038] The graft can be made of any suitable graft material. Examples of suitable materials include mesh material, woven materials, such as fabric and Dacron (Dacron is a registered trademark of the E.I. DuPont DeNemours Company), and synthetics such as polypropylene. Also, natural materials such as collagen and extracellular matrix (ECM) materials can be used. A preferred graft material is small intestine submucosa (SIS), such as SIS harvested from swine. The preparation and use of SIS, in contexts other than that of the present invention, are known to those skilled in the art. Descriptions of this material and procedures for its preparation can be found in U.S. Pat. No. 4,902,508 to Badylak et al. for TISSUE GRAFT COMPOSITION, which is hereby incorporated into this disclosure in its entirety.

[0039] The graft <b>16</b> may define structural features that facilitate attachment of the graft <b>16</b> to the support frame <b>12</b> by the connectors <b>14</b>. As illustrated in FIG. 1, for example, the graft <b>16</b> may define one or more apertures <b>26</b> that are able to receive a connector <b>14</b>, such as a barb formed of twisted frame threads <b>18</b>. The structural features can vary depending on the type and number of connectors <b>14</b> present on the support frame.

[0040] The graft assembly of the present invention is particularly well-suited for the repair of various types of vessels in patients. For example, the assembly can be used to provide artificial support to a weakened or blocked vessel. To be used in this manner, the graft assembly must be delivered to the site of interest and deployed, i.e., changed from a radially compressed configuration to a radially expanded configuration, from inside the lumen of the vessel.

[0041]FIG. 4A illustrates a preferred embodiment of a vessel repair system <b>200</b> according to the present invention. The vessel repair system incorporates a graft assembly <b>210</b> according to the present invention (detail of the graft assembly <b>210</b> is illustrated in FIG. 4B). As a result, reference numbers in FIG. 4B refer to similar features and/or components of the graft assembly as illustrated in the previous figures, but are a 200 series of numbers.

[0042] With reference to both FIGS. 4A and 4B, the vessel repair system <b>200</b> comprises a graft assembly <b>210</b>, and a deployment device <b>260</b>. The deployment device <b>260</b> comprises first <b>262</b> and second <b>264</b> sleeves. The first sleeve <b>262</b> has a proximal and <b>266</b>, a distal end <b>268</b>, and an inner surface <b>270</b> defining a first interior lumen <b>272</b>. The second sleeve <b>264</b> also has a proximal end <b>274</b> and a distal end <b>276</b>. The second sleeve <b>264</b> has an outer surface <b>278</b> and defines a second interior lumen <b>280</b>.

[0043] The second sleeve <b>264</b> extends coaxially with the first sleeve <b>262</b> and is disposed within the first interior lumen <b>272</b> of the first sleeve <b>262</b>. An annular space <b>282</b> is formed between the outer surface <b>278</b> of the second sleeve <b>264</b> and the inner surface <b>270</b> of the first sleeve <b>262</b>.

[0044] The support frame <b>212</b> of the graft assembly <b>210</b> is disposed substantially within the second interior lumen <b>280</b> such that only the first end of the support frame <b>212</b> and the associated connectors <b>214</b> extend beyond the distal ends <b>268</b>, <b>276</b> of the first <b>262</b> and second <b>264</b> sleeves. The graft <b>216</b> is attached to the support frame <b>212</b> by the connectors <b>214</b> as described above. The graft <b>216</b> is not connected to the second end of the support frame <b>212</b> and, as illustrated in FIG. 4B, is physically separated from the second end of the support frame <b>212</b> by the second sleeve <b>264</b>.

[0045] Except for the portion that extends beyond the distal ends <b>268</b>,<b>276</b> of the first <b>262</b> and second <b>264</b> sleeves for attachment to the support frame <b>212</b>, the graft <b>216</b> is substantially disposed in the annular space <b>282</b> between the first <b>262</b> and second <b>264</b> sleeves. When stored in the deployment device <b>260</b>, the support frame <b>212</b> of the graft assembly <b>210</b> is in the radially compressed configuration. As a result, the graft <b>216</b> may not be drawn taught to the surface of the second sleeve <b>264</b>. Consequently, as illustrated in FIG. 4B, the graft <b>216</b> is preferably repeatedly folded in the annular space <b>282</b> to facilitate its storage.

[0046] The deployment device <b>260</b> also includes a driving member <b>284</b>. The driving member <b>284</b> has an operating end <b>286</b> that terminates at a handle assembly <b>290</b>. A driving end <b>288</b> is disposed adjacent the second end of the support frame <b>212</b> within the second sleeve <b>264</b>. An operator is able to force the support frame <b>212</b> and attached graft <b>216</b> out of the deployment device <b>260</b> by pushing on the operating end <b>286</b> of the driving member <b>284</b> such that the driving end <b>288</b> forces movement of the support frame <b>212</b> relative to the first <b>262</b> and second <b>264</b> sleeves. As illustrated in FIGS. 5A and 5B, the support frame <b>212</b> takes on the radially expanded configuration as it exits the deployment device <b>260</b>. As a result, the graft <b>216</b> is drawn substantially taught against the surface of the support frame <b>212</b>, as best illustrated in FIG. 5B.

[0047] Thus, a preferred method of placing a graft on a support frame comprises providing a vessel repair system according to the present invention and manipulating the operating end of the driving member such that the driving end forces the support frame out of the second lumen. As the support frame exits, it pulls the graft out of the annular space. As best illustrated in FIG. 5B, the graft gradually unfolds from within the annular space and extends substantially along the entire length of the support frame as the support frame changes from the radially compressed configuration to the radially expanded configuration.

[0048] The method described above is particularly well-suited for placing the graft assembly at a point in the vessel that is in need of artificial support. FIG. 6 illustrates a schematic of this process, in which an operator inserts the distal ends <b>268</b>,<b>276</b> of the first <b>262</b> and second <b>264</b> sleeves into the lumen of a vessel <b>294</b> of a patient and moves these ends <b>266</b>,<b>274</b> to a point <b>296</b> in the vessel <b>294</b> that is in need of the artificial support. Techniques for inserting a deployment device into a vessel of a patient and navigating the device to the site of interest are known to those skilled in the art and will not be described in detail herein. The support frame <b>212</b> is forced out of the deployment device <b>260</b> as described above. The frame <b>212</b> expands and places the graft <b>216</b> at the weakened point <b>296</b> of the vessel <b>294</b>. The graft <b>216</b> is secured in this position by an outward force from the frame <b>212</b>.

[0049] The foregoing disclosure is the best mode devised by the inventor for practicing the invention. It is apparent, however, that several variations in intraluminal graft assemblies in accordance with the present invention may be conceivable by one skilled in the art. Inasmuch as the foregoing disclosure is intended to enable one skilled in the pertinent art to practice the instant invention, it should not be construed to be limited thereby, but should be construed to include such aforementioned variations. As such, the present invention should be limited only by the spirit and scope of the following claims.