US20070118208A1

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Publication number: US20070118208A1
Application number: US11/655,315
Authority: US
Inventors: Andrew Kerr
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-06
Filing date: 2007-01-19
Publication date: 2007-05-24
Also published as: US7175651B2; US20030074050A1

Abstract

A stent/graft assembly includes a tubular graft having an upstream end, a downstream end and a tubular passage between the ends. The assembly also includes a tubular stent having an upstream end, a downstream end and a tubular passage. The upstream end of the tubular graft is affixed in substantially end-to-end relationship with the downstream end of the tubular stent. The affixation may employ sutures, bonding, hooks or the like. The end-to-end connection may also require a slight overlapping to ensure an adequate affixation. The end-to-end disposition of the tubular graft and tubular stent reduces the cross-sectional profile of the stent/graft assembly. One or more wires may extend from the tubular stent through the tubular graft for anchoring near the downstream end of the tubular graft. The wire prevents axial collapsing of the tubular graft and provide radial support for the tubular graft.

Description

This application is a divisional of application Ser. No. 10/299,882 which is a continuation-in-part of application Ser. No. 09/961,825 and which, in turn, is a continuation-in-part of application Ser. No. 09/900,241.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to a stent and graft assembly for treating vascular anomalies, such as aneurysms.

2. Description of the Related Art

Vascular anomalies are considered to include blood vessels that are damaged, weakened or otherwise impaired. The anomaly may include a local change in the cross-sectional dimensions of the blood vessel. For example, aneurysms include a local area where a blood vessel expands to a larger cross-sectional area due to disease, weakening or other damage.

The aorta extends from the heart and through the abdomen. The abdominal aorta then feeds abdominal organs and the right and left iliac arteries that bring blood to the right and left legs respectively. The aorta is prone to aneurysms. Aortic aneurysms that are not treated in a timely manner can lead to rupture, occlusion, infection or the production of emboli which can flow downstream and occlude a smaller blood vessel. A ruptured aortic aneurysm typically is fatal due to a loss of the large volume of blood that flows through the abdominal aorta.

Aneurysms can be corrected by grafts. The typical graft is implanted surgically by accessing the site of the aneurysm, cutting open the aneurysm and then surgically forming an appropriate fabric into a tubular shape that spans the aneurysm. Thus, upstream and downstream ends of the prior art graft are sutured to healthier regions of the blood vessel.

The prior art also includes endovascular grafts. An endovascular graft comprises a flexible tubular member formed from a synthetic fabric. The graft is selected to have an outside cross-sectional dimension that approximates the inside cross-sectional dimensions of the blood vessel on either side of the aneurysm. The graft also is selected to have a length that exceeds the length of the damaged area of the blood vessel. An unsupported flexible tubular graft has a tendency to collapse in the presence of the flowing blood and could be transported downstream by the blood flow. As a result, endovascular grafts are used in combination with a stent. Stents take many forms, including balloon expandable stents and self-expanding stents, but typically are resilient cylindrical members that are inserted axially through the tubular graft prior to insertion into the blood vessel. The stent and the graft are sutured together prior to deployment so that the opposed ends of the stent align with the opposed ends of the graft. The endovascular graft assembly then is inserted through a healthy region of the blood vessel and is advanced through the circulatory system to the aneurysm or other damaged region of the blood vessel. More particularly, the endovascular graft assembly is advanced to a position where the endovascular graft assembly bridges the aneurysm or other damaged portion of the blood vessel. However, the opposed axial ends of the endovascular graft assembly extend beyond the aneurysm. The stent then is expanded to hold the graft in an expanded tubular condition with at least the opposed axial end regions of the graft being urged tightly against the interior of healthy regions of the blood vessel. The stent and the graft of the prior art endovascular graft assembly are coaxial, and longitudinally coextensive.

Prior art assemblies of stents and grafts typically perform well. However, the coaxially and longitudinally coextensive arrangement of the stent and graft has resulted in a cross-sectionally large assembly. A cross-sectionally large graft and stent assembly can be difficult to insert and deliver intravascularly to the damaged section of the blood vessel and may require surgery.

The inventor herein has developed low-profile stent/graft structures, as shown for example in U.S. Pat. No. 6,015,422, U.S. Pat. No. 6,102,918 and U.S. Pat. No. 6,168,620.

In view of the above, it is an object of the subject invention to provide improvements in vascular stent and graft assemblies that provide a small cross-section and low profile.

It is also an object of the invention to provide an endovascular stent and graft assembly that can be introduced easily into and through the damaged or diseased section of a blood vessel.

A further object of the subject invention is to provide a system of endovascular stents and grafts that can be assembled intravascularly through damaged regions of a blood vessel.

Another object of the invention is to provide an endovascular stent/graft assembly that prevents migration of the assembly after deployment.

An additional object of the invention is to provide an endovascular stent/graft assembly for treating patients with short and/or angulated vascular necks adjacent an aneurysm.

Yet another object of the invention is to provide a system of endovascular grafts and stents that will prevent an aneurysm from filling with blood that flows into the aneurysm from small side blood vessels.

SUMMARY OF THE INVENTION

The subject invention is directed to an endovascular graft assembly that comprises at least one tubular vascular graft and at least one fixation device. The tubular graft and the fixation device are connected substantially in end-to-end relationship with little or no longitudinal overlap. In certain embodiments, the substantially end-to-end relationship of the tubular graft and the fixation device may include a small axial space between the tubular graft and the fixation device. One or more connecting wires may bridge the space between the axially align tubular graft and fixation device. The tubular graft has a length that exceeds the length of a damaged section of a blood vessel that is being repaired by the endovascular graft assembly. The tubular graft also has a cross-sectional size that is about 10%-30% wider than the cross-sectional size of the blood vessel that is being repaired. The tubular graft preferably is formed from a synthetic material, such as a material formed from an ultra thin polyester fiber, or other vascular graft materials known to those skilled in this art.

The fixation device may comprise a generally tubular stent. One end of the tubular stent is securely affixed to one end of the tubular graft. The end-to-end fixation of the graft to the stent preferably is carried out with little or no telescoping between the tubular graft and the stent. However, a slight amount of telescoping (e.g. 0-20 mm) may be required to ensure a secure and substantially permanent interengagement. The connection between the tubular graft and the tubular stent may be achieved by hooking, stitching, fusing or other such secure connection techniques. The connection need not be continuous around the peripheries of the stent and the tubular graft. Thus, the stent and the tubular graft merely may be connected at one location on their respective ends or at plural spaced-apart locations.

The fixation device need not be a tubular stent. Rather, the fixation device may comprise a plurality of hooks that extend from at least one longitudinal end of the tubular graft. The hooks can be engaged with healthy sections of blood vessel on either side of an aneurysm. The fixation device may further include an annular ring affixed to an axial end of the tubular graft, and the hooks may project axially from the ring. The ring functions to keep the tubular graft open during insertion of the endovascular graft assembly into the blood vessel.

The endovascular graft assembly further comprises an internal stent to provide radial support for the tubular graft of the endovascular graft assembly. However, unlike prior art endovascular graft assemblies, the internal stent of the subject invention is deployed after the end-to-end assembly of the fixation device and tubular graft have been positioned properly across the aneurysm. The internal stent may be a balloon expandable stent or a self-expanding stent. However, the insertion of the internal stent after the insertion of the end-to-end assembly of the fixation device and tubular graft greatly facilitates the deployment of the entire endovascular stent/graft assembly to the proper location.

The endovascular graft assembly may further include at least one support that extends from the fixation device into the graft to prevent the graft from collapsing radially or axially during or after installation and/or to provide radially outward support for the graft. The support may comprise at least one longitudinally extending wire extending from the fixation device substantially entirely through the graft and then anchored at the axial end of the graft opposite the stent. The support may alternatively comprise a coil extending substantially from the fixation device, through the graft and to the end of the graft opposite the fixation device. The support may be connected to the fixation device or unitary with portions of the fixation device.

The endovascular graft assembly may comprise at least two fixation devices connected respectively to opposite ends of a tubular graft. The endovascular graft assembly may further comprise a plurality of tubular grafts connected respectively to opposite axial ends of fixation devices. The tubular graft and tubular fixation devices need not be all of identical cross-sectional sizes. Additionally, the assembly may comprise plural fixation devices connected axially to the legs or branches of a bifurcated or trifurcated graft, such as a graft having an inverted Y-shape. Furthermore, certain components of the assembly may be assembled intravascularly and intraoperatively. The end-to-end connection of a tubular fixation device and a tubular graft provides advantages over a graft that is at least partly coextensive with a tubular stent. In particular, the cross-sectional dimension of the preferred assembly is smaller than an assembly with the tubular graft and tubular stent at least partly coextensive with one another, and hence insertion is easier. However, the end-to-end axial connection of a tubular graft with a tubular fixation device has advantages that can be applied to a coextensive tubular graft and tubular stent. For example, one or more tubular grafts may be assembled preoperatively with one or more tubular stent. This assembly can include a single tubular graft with a single tubular stent inwardly therefrom, a tubular graft with a plurality of axially spaced tubular stents inwardly therefrom or an assembly with one or more tubular stents disposed between concentrically disposed inner and outer tubular grafts. Any of these tubular stent/graft assemblies can be connected in end-to-end relationship with a fixation device. Such an end-to-end combination would not achieve the small cross-section and easy insertion of the above reference preferred embodiment. However, the end-to-end connection of a fixation device and an assembly with a tubular graft and one or more tubular stents can achieve enhanced fixation and can prevent the assembly of the tubular graft and tubular stents from drifting in the blood vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational, partly in section, view of an endovascular stent/graft assembly in accordance with a first embodiment of the invention.

FIG. 2 is an enlarged elevational view, partly in section, of a connection between the stent and graft of the assembly in eitherFIG. 1.

FIG. 3 is an enlarged elevational view partly in section, similar toFIG. 2, but showing an alternate connection between the stent and the graft.

FIGS. 4A and 4B are enlarged elevational views, partly in section, showing a further alternate connection between the stent and the graft.

FIG. 5 is an elevational view of the graft with hooks for fixation to the stent or to a blood vessel.

FIG. 6 is an elevational view similar toFIG. 5, but showing hooks on the tubular stent.

FIG. 7 is an elevational view of an endovascular stent/graft assembly in accordance with a second embodiment of the invention.

FIG. 8 is a schematic illustration of the endovascular stent/graft assembly ofFIG. 1 inserted into a blood vessel.

FIG. 9 is a schematic illustration of an insertion of the endovascular stent/graft assembly ofFIG. 1 into the abdominal aorta.

FIG. 10 is a schematic illustration of the endovascular stent/graft assembly ofFIG. 1 deployed through the right iliac artery and then inserted into the left iliac artery.

FIG. 11 is an elevational view, partly in section of a third alternate endovascular stent/graft assembly.

FIG. 12 is a perspective view of a fourth embodiment of an endovascular stent/graft assembly in accordance with the subject invention.

FIG. 13 is a perspective view of an endovascular stent/graft assembly in accordance with a fifth embodiment of the subject invention.

FIG. 14 is a side elevational view of the endovascular stent/graft assembly ofFIG. 13 with a cross-sectional variation along the length of the graft to accommodate cross-sectional variations of the blood vessel.

FIG. 15 is a schematic view of a modular endovascular stent/graft assembly that represents a sixth embodiment of the invention intended primarily for deployment into the abdominal aorta and adjacent regions of the left and right iliac arteries.

FIG. 16 is a schematic view of a seventh embodiment of an endovascular stent/graft assembly in accordance with the invention.

FIG. 17 is a schematic view of an eighth embodiment of an endovascular stent/graft assembly in accordance with the invention.

FIG. 18 is a schematic view of a variation of the eighth embodiment.

FIG. 19 is a schematic view of a modular endovascular stent/graft assembly that represents a ninth embodiment of the invention intended primarily for deployment into the abdominal aorta and adjacent regions of the left and right iliac arteries.

FIG. 20 is a schematic view of a variation of the stent/graft assembly ofFIG. 19.

FIG. 21 is a schematic view of a tenth embodiment of an endovascular stent/graft assembly in accordance with the invention.

FIG. 22 is a schematic view of an eleventh embodiment of an endovascular stent/graft assembly in accordance with the invention.

FIG. 23 is a schematic view of a twelfth embodiment of an endovascular stent/graft assembly in accordance with the invention.

FIG. 24 is a schematic view of a thirteenth embodiment of an endovascular stent/graft assembly in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An endovascular stent/graft assembly in accordance with a first embodiment of the invention is identified generally by the numeral10 inFIG. 1. The endovascular stent/graft assembly10 includes a substantiallytubular graft12 having a flexible wall formed from a synthetic material, such as a polyester material that is substantially impervious to fluid transmission or that becomes substantially impervious after exposure to blood. Thetubular graft12 has anupstream end14, adownstream end16 and afluid passage18 extending between the ends. The endovascular stent/graft assembly10 further comprises atubular stent20 having anupstream end22, adownstream end24 and apassage26 extending between the ends. Thetubular stent20 may be of known construction and may be formed from materials that are known to those skilled in the art of treating vascular anomalies with endovascular stent/graft assemblies, such as polyethylene terepthalate and PTFE, including materials sold under the trademarks DACRON® and GORTEX®.

The terms upstream and downstream used to define the ends of thetubular graft12 and thetubular stent20 are employed with reference to the direction of blood flow existing during insertion of astent graft assembly10. More particularly, the endovascular stent/graft assembly preferably will be inserted into a blood vessel such that thetubular stent20 is upstream and facing into the flow of blood. Thetubular graft12 then will trail behind the stent relative to the direction of insertion of the endovascular stents/graft assembly10 and relative to the direction of the blood flow. This preferred orientation of the endovascular stent/graft assembly10 will enable the much more flexibletubular graft12 to perform much in the nature of a wind-sock that is urged into an extended condition by forces exerted by the blood flow. A reversed insertion, of this first embodiment, on the other hand, could cause the flexibletubular graft12 to collapse in response to the blood flow.

As shown generally inFIG. 1 and more specifically inFIGS. 2 and 3, thetubular graft12 and thetubular stent20 are connected substantially in end-to-end axial relationship. More particularly, as shown inFIG. 2, theupstream end14 of thetubular graft12 is butted against thedownstream end24 of thetubular stent20 to achieve a true end-to-end axial connection between thetubular graft12 and thetubular stent20. This pure axial end-to-end abutment can be achieved by fusing, suturing or other known connection means that will be appreciated by persons skilled in this art.

The true end-to-end axial connection may be difficult to achieve with certain material employed for the tubular graft and the tubular stent. In these situations, a substantially end-to-end axial connection can be achieved with a slight telescoping overlap as shown schematically inFIG. 3. With this optional arrangement, the inner circumferential surface of thetubular graft12 adjacent theupstream end14 may be telescoped slightly over the outer circumferential surface of thetubular stent20 adjacent thedownstream end24. Sutures, fusing or other known connections then may be employed to permanently affix the slightly overlapped ends of thetubular graft12 and thetubular stent20.

FIGS. 2 and 3 depict substantially continuous connection between the annular periphery at the upstream end of thetubular graft12 and the annular periphery at thedownstream end24 of thetubular stent20. However, such a continuous connection may not be required in many situations. Rather, one or more points of contact and affixation may be sufficient between theupstream end14 of thetubular graft12 and the downstream end of thetubular stent20. As noted above, end-to-end axial connection may comprise true end-to-end connection or a connection with a slide telescope overlap between thetubular graft12 and thetubular stent20, as shown inFIG. 3.

As a further alternate, substantially end-to-end axial relationship may comprise an axial gap between thetubular graft12 and thetubular stent20, as shown inFIGS. 4A and 4B.FIG. 4A shows the general concept of an axial gap between thetubular graft12 and thetubular stent20 prior to deployment.FIG. 4B shows one optional deployment. The axial spacing can provide even further advantages for the deployment and positioning of thetubular graft12 and thetubular stent20. In this embodiment, at least one connectingwire15 is connected to both thetubular graft12 and thetubular stent20 and bridges the gap between the axially alignedtubular graft12 andtubular stent20. The connectingwire15 maintains the spaced disposition between thetubular graft12 and thetubular stent20. In this embodiment, as well as others, aguide wire17 may be used to guide the stent/graft assembly10 during deployment. With reference toFIG. 4B, thetubular stent20 may be disposed upstream from the renal arteries and upstream from the visceral arteries shown by broken lines inFIG. 4. Thetubular graft12 has an upstream end disposed between the aneurysm and the renal arteries. Thewires15 extend between thegraft12 and thetubular stent20. Hence, the stent/graft assembly is anchored efficiently in a healthy section of the aorta upstream from the aneurysm. Additionally, blood flow to and from the renal arteries and the visceral arteries is ensured by the axial gap between thetubular graft12 and thestent20. Thewires15 bridge the gap between thegraft12 and thestent20.

The endovascular stent/graft assembly12 further comprises aninternal stent27 that is deployed after the end-to-end connectedtubular graft12 andtubular stent20 are in place. Theinternal stent27 may be a balloon expandable stent or a self-expanding stent and functions to maintaintubular graft12 in an expanded non-occluded condition. Furthermore, theinternal stent27 maintains outer circumferential surface regions of thetubular graft12 near the upstream and downstream ends14 and16 in face-to-face engagement with the inner surface of the blood vessel upstream and downstream from the aneurysm. The insertion of theinternal stent27 after positioning thetubular graft12 and thetubular stent20 is considerably easier than the prior art endovascular grafts that simultaneously attempt to advance a coaxial arrangement of graft and stent that are longitudinally coextensive with one another.

An alternate end-to-end connection between thetubular graft12, as shown inFIG. 5, includes a plurality of hooks28 woven or otherwise incorporated into thetubular graft12 to extend axially beyond at least theupstream end14. The hooks28 on theupstream end14 of thetubular graft12 can be engaged into the circumferential surface of the blood vessel. Thus, the hooks28 function as a fixation device that is an alternate to thetubular stent20 shown inFIGS. 1-3. The hooks28 can be mounted to an annular ring (not shown) that can be affixed to theupstream end14 of thetubular graft12. Thus, the combination of the ring and the hooks28 may function as the fixation device. A variation of theFIG. 5 embodiment, the hooks28 at theupstream end14 of thetubular graft12 can be engaged into portions of thetubular stent20 adjacent thedownstream end24. Alternatively, as shown inFIG. 6, hooks30 may extend axially beyond thedownstream end24 of thetubular stent20 for engagement with portions of thetubular graft12 adjacent theupstream end14.

FIG. 7 shows an endovascular stent/graft assembly32 in accordance with a second embodiment of the invention. The endovascular stent/graft assembly32 includes atubular graft12 substantially identical to thetubular graft12 in the embodiment ofFIG. 1. The stent/graft assembly32 further includes an upstreamtubular stent20 substantially identical to thetubular stent20 in the embodiment ofFIG. 1. However, the stent/graft assembly32 further includes adownstream stent34. Thedownstream stent34 has anupstream end36, adownstream end38 and atubular passage40 extending between the ends. Theupstream end36 of thedownstream stent34 is connected in substantially end-to-end relationship with thedownstream end16 of thetubular graft12 by any of the connection arrangements depicted respectively inFIGS. 2-6. Thedownstream stent34 can be connected to the tubular graft prior to insertion of the stent/graft assembly32 into the blood vessel. Alternatively, the sub-assembly of thetubular graft12 and theupstream stent20 can be inserted into the blood vessel substantially as shown inFIG. 1. Thedownstream stent34 then can be inserted subsequently and connected intraoperatively to thedownstream end16 of thetubular graft12.

As noted above, and as illustrated generally inFIG. 1, the endovascular stent/graft assembly10 is fixed into the blood vessel with thetubular graft12 in a downstream position relative to thetubular stent20. This orientation, does not, however, imply a required direction of insertion. For example, as depicted inFIG. 8, a catheter C is employed to insert the endovascular stent/graft assembly10 into a blood vessel V along the direction of flow and thetubular graft12 leading thetubular stent20. Thus, despite the slow movement of the catheter C and the stent/graft assembly10 through the blood vessel V in the direction of the blood flow, thetubular graft12 will extend axially beyond thetubular stent20 with a substantially wind-sock effect as described above and as shown inFIG. 8. Alternatively, the catheter C can be used to insert the endovascular stent/graft assembly10 in opposition to the direction of blood flow, but with thetubular stent20 in the upstream position and leading the endovascular stent/graft assembly10 into the direction of blood flow. More specifically,FIG. 9 schematically depicts the insertion of the endovascular stent/graft assembly10 through the rightiliac artery40 and into theabdominal aorta42, with thetubular stent20 in the upstream position relative to thetubular graft12, and with thetubular stent20 leading the insertion against the direction of blood flow.

In certain procedures, the stent/graft assembly may start in a direction against the flow of blood but move into a different blood vessel to follow the flow of blood. More particularly,FIG. 10 depicts the insertion of the stent/graft assembly10 into the rightiliac artery40 for eventual insertion into the leftiliac artery44. The initial part of this insertion will have the endovascular stent/graft assembly10 inverted relative to the preferred and eventual orientation. Thus, thetubular graft12 may initially be in an upstream position, and accordingly may collapse somewhat during the initial stages of the insertion. However, thetubular graft12 of the stent/graft assembly will move into the downstream position relative to thetubular stent20 as the stent/graft assembly10 moves into the leftiliac artery44. Thus, any collapsing of the moreflexible graft12 that may have occurred during initial insertion through the rightiliac artery40 will be offset by the above-described wind-sock effect as the stent/graft assembly10 moves into the leftiliac artery44.

A fourth embodiment of the endovascular stent/graft assembly is identified by the numeral50 inFIG. 12. The endovascular stent/graft assembly50 is a variation of the stent/graft assembly46 ofFIG. 11 in that a plurality ofwires52 extend axially from thestent20 substantially to thedownstream end16 of thetubular graft12 where thewires52 are affixed to thetubular graft12. The stent/graft assembly50 prevents axial collapsing of thetubular stent20, substantially as with the embodiment ofFIG. 11. However, thewires52 will further provide radially support for thetubular graft12 and will resist radially collapsing of thegraft12.

A fifth embodiment of the endovascular stent/graft assembly is identified by the numeral54 inFIGS. 13 and 14. The stent/graft assembly54 is similar to the stent/graft assemblies ofFIGS. 11 and 12. However, the axially aligned wires of the previous embodiment are replaced with acoil56. Thecoil56 may be anchored to thetubular stent20 or to theupstream end14 of thetubular graft12 for affixation to thedownstream end16 of thetubular graft12. Thecoil56 resists axially collapsing and will assist with axial extension in response to any axial collapse that does occur. Additionally, thecoil56 provides greater outwardly directed radially forces on thetubular graft12 then either of the previous embodiments.

The endovascular stent/graft assembly32 ofFIG. 7 shows that a plurality of

stents

20,34 can be assembled with a singletubular graft12. The principles embodied inFIG. 7 can be employed further to develop more complex modular assemblies. For example,FIG. 15 shows a modular assembly for repairing vascular anomalies in the region where theabdominal aorta42 meets the rightiliac artery40 and the leftiliac artery44. In particular, the modular endovascular stent/graft assembly58 comprises a firstmodular subassembly60 with a firsttubular stent62 with anupstream end64 and an opposeddownstream end66. The firstmodular subassembly60 further comprises a firsttubular graft68 with anupstream end70 connected substantially in end-to-end axial relationship with thedownstream end66 of thefirst stent62. The firsttubular graft68 further includes adownstream end72. The firstmodular component60 is deployed from a right leg approach into the rightiliac artery40. The firsttubular stent62 then is advanced sufficiently into theabdominal aorta42 for the firsttubular stent62 to be upstream of the aneurysm or other vascular abnormality in theabdominal aorta42.

Themodular assembly60 further includes a secondtubular stent74 that is mounted unrestrained in the firsttubular graft68 at a location downstream from or within the aneurysm. The firsttubular graft68 further includestubular exit76 at a location between the secondtubular stent74 and thedownstream end72 of the first tubular graft. The secondtubular stent74 preferably is cross-sectionally larger than both theexit76 and portions of the firsttubular graft68 in proximity to theexit70. Thus, the unrestrained secondtubular stent74 will not slip longitudinally into either theexit76 or downstream portions of the firsttubular graft68.

Theassembly58 further includes a secondtubular graft78 with anupstream end80 and adownstream end81. The secondtubular graft78 is deployed from a left leg approach into the leftiliac artery44 and is advanced through theexit76 of the firsttubular graft68. Theupstream end80 of the secondtubular graft78 is connected substantially end-to-end with the secondtubular stent74. Internal stents then may be inserted, such as theinternal stent27 described with respect to the first embodiment.

A seventh embodiment of the endovascular stent/graft assembly of the subject invention is identified generally by the numeral82 inFIG. 16. Theassembly82 comprises first and second endovascular stent/

graft subassemblies

83 and84. Thefirst subassembly83 comprises afirst stent85 and a firsttubular graft86. Similarly, thesecond subassembly84 comprises asecond stent87 and asecond graft88. Theassembly82 further includes a generally disc-like drum secured in theabdominal aorta42 at a location upstream of the aneurysm. Thedrum90 has first and second mounting

apertures

92 and94 through which portions of the first and second

tubular grafts

86 and88 extend. The extreme upstream ends of the

tubular grafts

86 and88 are secured respectively in end-to-end relationship with the downstream end of the first and second

tubular stents

85 and87, while the downstream ends of the

tubular grafts

86 and88 are disposed respectively in the right and left

iliac arteries

40 and44. The drum ordisc90 prevents blood from flowing around the

tubular grafts

86 and88 and into the region of the aneurysm where blood pressure could cause a rupture of the aneurysm. The

stents

85 and87 provide a secure mounting of the endovascular stent/graft assembly82 relative to the aneurysm, and prevent any parts of theassembly82 from migrating downstream due to the pressure of the blood flow. The endovascular stent/graft assembly82 ofFIG. 16 is used in combination with internal stents, such as theinternal stent27 inFIG. 1, that are introduced to the

tubular grafts

86 and88 after complete implantation of portions of theassembly82 depicted inFIG. 16. Additionally, theassembly82 may be used in combination with one or two downstream stents, or other fixation devices secured to downstream ends of the respective

tubular grafts

86 and88.

An eighth embodiment of the endovascular stent/graft assembly of the subject invention is identified generally by the numeral96 inFIG. 17. The stent/graft assembly96 is designed in recognition of the fact that somewhat less than half of all patients have a neck defined in the abdominal aorta immediately upstream of the aneurysm. The neck is aligned to the aneurysm at an angle of less than 180°. Endovascular stent/graft assemblies exhibit some flexibility. Thus, a conventional cylindrical endovascular stent/graft assembly can be biased into a noncylindrical curved shape that conforms to the shape of the neck adjacent the aneurysm. However, an initially cylindrical stent/graft assembly with a linear axis of symmetry that is biased into a curved noncylindrical shape will exhibit internal resiliency that will tend to return the stent/graft assembly back to an unbiased cylindrical configuration.

A stent/graft assembly that initially is concentric about a linear axis and then is bent to be concentric about a curved axis will cause portions of the stent/graft assembly on the outside of the curve to circumscribe a smaller arc angle than portions of the stent/graft assembly more inwardly on the curve. As a result, portions of the cylindrical stent/graft assembly that initially are concentric about a linear axis and then are curved to be concentric about a curved axis will be affixed less securely in healthy regions of the blood vessel upstream from the aneurysm and on the outside of the curve of the stent/graft assembly. This configuration is illustrated by the broken line on the endovascular stent/graft assembly96 shown inFIG. 17. It will be appreciated that even minor shifting of the endovascular stent/graft assembly after implantation can result in catastrophic leaks between the stent/graft assembly and the aneurysm.

To avoid the above-described problems, the endovascular stent/graft assembly96 shown inFIG. 17 is preformed to be unbiased in a curved condition symmetrical about a curved axis. Thus, the stent/graft assembly96 can be considered to define a section of torus. Additionally, theupstream end97 is substantially perpendicular to the curved axis of the stent/graft assembly. This requires the stent/graft assembly96 to be longer on the outside of the curve than on the inside of the curve so that portions of the stent/graft assembly96 circumscribes substantially equal angles on both inner and outer extremes of the curved stent/graft assembly96. The curve in the endovascular stent/graft assembly96 can be achieved by providing longitudinally extending fibers or filaments in the stent and/or the graft that have a preset curve, and aligning the curve filaments, fibers or wires to be substantially parallel with one another. Alternatively, longitudinal extending filaments, fibers or wires on one side of the curve endovascular stent/graft assembly96 may be shorter than those on the opposite longitudinal side. Still further, a preset unbiased curved can be achieved by appropriate heat treatment of an initially cylindrical stent.

The stent/graft assembly96 can be biased from its preset curved or toroidal condition back into a substantially cylindrical condition for deployment. This biased cylindrical shape can be maintained by the introducer that is use during deployment. The introducer is removed substantially in the conventional manner after proper positioning of the stent/graft assembly96. At that time, the stent/graft assembly96 will be released from its biased cylindrical configuration and will return to its preset unbiased curved or toroidal configuration substantially confirming to the shape imparted by the neck upstream from the aneurysm. The preceding embodiments all relate to stent/graft assemblies where the graft is fixed in substantially end-to-end relationship with the stent. Such a configuration also is acceptable for the stent/graft assembly96. However, the curved stent/graft assembly96 also is effective for those situations where the stent and the graft are longitudinally coextensive with one another and where the upstream and downstream ends of both the stent and the graft are at the same or similar axial positions.

FIG. 18 shows an angulated endovascular stent/graft assembly196 that is provided for situations similar to those described above with respect toFIG. 17. The endovascular stent/graft assembly196 includes astent196 with anupstream end200, adownstream end202 and alongitudinal axis204 extending therebetween. Theupstream end200 is aligned substantially orthogonal to thelongitudinal axis204 of thestent198. The downstream end, however, is not perpendicular to theaxis204, and hence defines a beveled end. The stent/graft assembly196 further includes atubular graft206 having anupstream end208, anddownstream end210 and anaxis212 extending between the ends. Thedownstream end210 is aligned substantially orthogonal to theaxis212. However, theupstream end208 is not orthogonal to theaxis212. Hence, theupstream end208 defines a beveled end. The beveledupstream end208 of thegraft206 is connected substantially and end-to-end relationship with the beveleddownstream end202 of thestent198. As in the previous embodiments, the end-to-end connection can be achieved by sutures, bonding, adhesive, welding, hooks or the like. Additionally, as with the preceding embodiments, the substantially end-to-end connection may include a small amount of overlap sufficient to achieve the connection. The end-to-end connection of the beveled ends202 and208 of thestent198 and thegraft206 respectively creates a bend that can more nearly approximate the shape of the blood vessel adjacent the angulated neck upstream of the aneurysm. This alternate embodiment provides certain practicalities over the embodiment ofFIG. 17. For example, the angle of bend can be controlled precisely by effectively mitering the ends at an appropriate angle. Second, insertion can be easier than with a stent/graft assembly that is curved along its length. In this latter regard, it will be appreciated that thegraft206 is very flexible and during insertion will collapse and readily follow thestent198 as thestent198 is inserted generally along itsaxis204.

FIG. 19 shows an endovascular stent/graft assembly98 with astent20, substantially identical to thestents20 described and illustrated above. More particularly, thestent20 of theassembly98 inFIG. 19 has opposed upstream and downstream ends22 and24. Theassembly98 includes a one piece bifurcatedgraft100. Thegraft100 includes anupstream end102 that is fixed in substantially end-to-end axial engagement with thedownstream end24 of thestent20. Additionally, thegraft100 includes two

downstream legs

104 and106 for disposition respectively in the right and left

iliac arteries

40 and44. The one piece bifurcatedgraft100 ofFIG. 19 eliminates some of the intraoperative assembly required with the modular system ofFIG. 15. Thebifurcated graft100 is used with one or more internal stents that are deployed after insertion substantially as described with respect to the other embodiments. Additionally, downstream stents can be affixed to either of the

downstream legs

104 and106.

Variations of theFIG. 19 embodiment also may be provided. For example, more than two legs may be provided. Furthermore thestent20 may have branches intermediate its length, and tubular grafts may be connected in substantially end-to-end relationship with the branches of the stent.

An example of a variation of theFIG. 19 embodiment is illustrated inFIG. 20. In particular,FIG. 19 shows an endovascular stent/graft assembly198 with astent20 identical to thestent20 described and illustrated above. Theassembly198 includes agraft200 with a tubularupstream end202 connected to thedownstream end24 of thestent20. Thegraft200 also has a tubulardownstream end204 and three

tubular branches

206,208 and210 extending transversely from intermediate positions along thegraft200.FIG. 20 shows the endovascular stent/graft assembly198 deployed for treating an aneurysm of thethoracic aorta212. The

tubular branches

206,208 and210 extend to arteries that branch from thethoracic aorta212, including the leftsubclavian artery216, the leftcarotid artery218 and thebrachiocephalic artery220.

In many instances, small blood vessels will communicate with portions of the abdominal aorta that have the aneurysm. Blood delivered by these blood vessels can increase pressure between the aneurysm and the graft. Such pressure can lead to a rupture of the aneurysm and/or damage to the graft. Theendovascular graft assembly108 ofFIG. 21 is specifically configured to occlude small side blood vessels that lead into the aneurysm. More particularly, theassembly108 includes an outer stent/graft subassembly110 that comprises an upstreamtubular stent112 and a downstreamexpandable graft114. Thestent112 andgraft114 are connected in substantially end-to-end axial alignment as described and illustrated with respect to the other embodiments herein. Thedownstream graft114 of the outer stent/graft subassembly110 differs from the tubular grafts described and illustrated above. More particularly, theouter graft114 may be a synthetic fabric or a detachable balloon that has been used in the prior art. Specifically, theouter graft114 can be expanded radially to conform substantially to the shape of the aneurysm and to thereby occlude the small blood vessels that lead into the aneurysm. Theassembly108 further includes an inner stent/graft subassembly116 that has anupstream stent118 and a downstreamtubular graft120. Theinner subassembly116 may be substantially identical to the endovascular stent/graft assembly10 described with respect toFIG. 1 and other embodiments set forth above. Thus, thetubular graft120 of theinner subassembly116 is not expandable. An inner stent similar to theinner stent27 described and illustrated above may extend through thetubular graft120. The space between the inner and

outer graft

114 and120 may be filled with blood, a contrast liquid, an adhesive or water. Variations of this embodiment may include a detachable balloon between theinner graft120 and the expandableouter graft114. Alternatively, the detachable balloon may make the separate inner graft unnecessary. Still further, the detachable balloon may make a separate internal stent for the outer graft unnecessary.

FIG. 22 shows a stent/graft assembly310 that incorporate features of the assemblies shown inFIGS. 14B. In particular, the stent/graft assembly310 includes agraft312 and astent320 that are connected substantially in end-to-end relationship. As in the preceding embodiment, thestent20 is intended for disposition adjacent a healthy section of the blood vessel upstream from an aneurysm. Thetubular graft312 typically will extend downstream from thestent320 across an aneurysm and into a location downstream from the aneurysm. However, many such aneurysms occur in the abdominal aorta slightly downstream from the renal arteries. Thestent320 often will take the form of a tubular wire mesh that normally should permit a blood flow through the tubular mesh and into the renal arteries. However, the tubular mesh of thestent320 can become blocked by materials flowing in the blood. Blockage of the renal arteries can lead to kidney failure and is more likely to occur with the wire mesh stent in place than without the wire mesh. Hence, the implantation of the stent/graft assembly10 ofFIG. 1 in the abdominal aorta with thestent320 aligned with the renal arteries could overcome the problems associated with the aneurysm, but could cause kidney problems due to blockage of the renal arteries. TheFIGS. 4A and 4B embodiments provide one solution to that problem.FIG. 22 provides another solution without the use of the connecting wires ofFIGS. 4A and 4B. In particular, thestent320 ofFIG. 22 has adownstream end324 defined by a plurality ofcrenulations325 that are separated bycutouts326 that extend axially a sufficient distance to overlap the renal arteries and visceral arteries. Thecrenulations325 at thedownstream end324 of thestent320 are affixed in substantially end-to-end relationship with the upstream end of thetubular graft312. Theaxially extending cutouts326 permit unimpeded blood flow to the renal arteries and visceral arteries.

FIG. 23 shows still a further alternative embodiment that may be adopted as an alternate to the embodiments ofFIG. 4B andFIG. 22. In particular, theassembly410 inFIG. 23 includes atubular graft412 with anupstream end414 and opposite downstream ends416 positioned in the iliac arteries. Theassembly410 further includeswires420 extending at least partly through thegraft412 and projecting upstream therefrom.Assembly410 does not have a tubular stent comparable to thetubular stent20 shown inFIGS. 4A and 4B. Rather, the upstream ends of thewires420 are formed with hooks orbarbs422 that permit anchoring of theassembly410 in a healthy section of a blood vessel that may be upstream from the aneurysm. The embodiment ofFIG. 23 also is well suited for treatment of an aneurysm in the abdominal aorta. In particular, theupstream end414 of thegraft412 can be positioned between the aneurysm and the renal arteries. Thewires420 extend to locations in the abdominal aorta upstream from the renal arteries and upstream from the visceral arteries. Thus, as in the embodiments shown inFIGS. 4B and 22, blood flow to the renal arteries and the visceral arteries is substantially unimpeded.

FIG. 24 shows still another embodiment that may be adopted as an alternate to the embodiments ofFIGS. 4B, 22 and23. In particular, theassembly510 inFIG. 24 includes atubular graft512 with anupstream end514 and opposite downstream ends516 positioned in the iliac arteries. Theassembly510 further includes atubular stent520 connected to theupstream end514 of thetubular graft512 in substantially end-to-end relationship. In the illustrated embodiment, thetubular stent520 is positioned in the abdominal aorta at a location upstream from the renal arteries.Apertures515 are formed in portions of thetubular graft512 near theupstream end514 to permit a flow of blood to the visceral arteries and the renal arteries. However, portions of thetubular graft512 closer to the downstream ends516 are substantially free of apertures. As illustrated inFIG. 24, these portions of thetubular graft512 without the apertures bridge the aneurysm.

While the invention has been described with respect to certain preferred embodiments, it is apparent that various changes can be made without departing from the scope of the invention as defined by the appended claims. For example, for each of the optional embodiments, and variations thereof, the substantially end-to-end stent-to-graft connections can be pure end-to-end abutment as depicted schematically inFIG. 2 or a slightly overlapped telescoped arrangement, as shown inFIG. 3. In other options, there may be a greater telescoping between the graft and stent prior to deployment and/or during deployment. However, the graft and stent then may be extended intraoperatively into the slightly overlapped relationship depicted inFIG. 3. Embodiments of the invention that show a curved stent/graft assembly with the stent and the graft substantially coextensive may comprise a single tubular graft with a plurality of stents disposed substantially in end-to-end relationship with one another or in axially spaced relationship to one another. At least certain of the stents may comprise a single ring or a short section of a helix. In these embodiments, the graft may be inside the one or more stents, outside the one or more stents or the assembly may have two tubular grafts disposed respectively inside and outside the one or more stents. Additionally, as noted above, at least a portion of a graft connected in end-to-end relationship with a stent may be connected preoperatively to its own stent. This later embodiment would not achieve a minimum cross-sectional dimension with a correspondingly easier insertion, but may achieve a more secure affixation than assemblies that rely upon only a coaxially coextensive stent and graft.

Claims

1. An endovascular stent/graft assembly for repairing a damaged section of a blood vessel, said blood vessel having a first relatively healthy section upstream of and adjacent to the damaged section of the blood vessel and second and third relatively healthy sections branched from one another and downstream of the damaged section of the blood vessel, said assembly comprising:

a stent means for directly contacting said first relatively healthy section of said blood vessel, said stent means being substantially tubular and having opposite upstream and downstream ends; and

a substantially tubular graft means having an upstream end section for directly contacting the first relatively healthy section of the blood vessel, the upstream end of the substantially tubular graft being fixedly connected with the downstream end of the stent means for achieving a substantially end-to-end connection, said graft means further having a downstream end section having at least two branches disposed for contacting the second and third relatively healthy sections of said blood vessel downstream of the damaged section of the blood vessel, such that portions of said graft means between said upstream and said downstream ends bridge said damaged section of said blood vessel.

2. The endovascular stent/graft assembly ofclaim 1, wherein the substantially end-to-end connection of said tubular graft means and said stent means is an end-to-end connection with no overlap.

3. The endovascular stent/graft assembly ofclaim 1, wherein said substantially end-to-end connection of said substantially tubular graft means and said stent means defines a small axial space therebetween.

4. The endovascular stent/graft assembly ofclaim 3, further comprising wires extending between the substantially tubular graft means and the stent means for maintaining a fixed spaced relationship therebetween.

5. An endovascular stent/graft assembly for repairing a damaged section of a first blood vessel, said first blood vessel having upstream and downstream relatively healthy sections adjacent and on opposite upstream and downstream ends of said damaged section, at least one branched blood vessel communicating with the first blood vessel, said assembly comprising:

a stent means for directly contacting said upstream relatively healthy section of said first blood vessel, said stent means being substantially tubular and having opposite upstream and downstream ends; and

a substantially tubular graft means having an upstream end for contacting said upstream relatively healthy section of said first blood vessel, said upstream end of said tubular graft means being fixedly connected with said down stream end of said stent means for achieving a substantially end-to-end connection, said graft means further having a downstream end section for directly contacting said downstream relatively healthy section of said first blood vessel, such that portions of said graft means between said upstream and downstream ends thereof bridge said damaged section of said first blood vessel, said graft means further comprising at least a first branch communicating with portions of said tubular graft means between said upstream and downstream ends thereof and communicating with said branched blood vessel.

6. The endovascular stent/graft assembly ofclaim 5, wherein the substantially end-to-end connection of said tubular graft means and said stent means is an end-to-end connection with no overlap.

7. The endovascular stent/graft assembly ofclaim 5, wherein said substantially end-to-end connection of said substantially tubular graft means and said stent means defines a small axial space therebetween.