GB2515731A

GB2515731A - Prosthesis

Info

Publication number: GB2515731A
Application number: GB1310918.6A
Authority: GB
Inventors: David Stevenson
Original assignee: Vascutek Ltd
Current assignee: Vascutek Ltd
Priority date: 2013-06-18
Filing date: 2013-06-18
Publication date: 2015-01-07
Also published as: GB201310918D0

Abstract

A stent-graft prosthesis 1 comprises a tubular sleeve 2 cojoined at one end with a first portion of a radially extending flange 3 which has a flange stent element 5 attached at a second portion. The tubular sleeve 2 has a lumen 4 which extends between a first end 52 and a second end 53 and is supported by spaced ring stents 5 attached to its outer diameter. The first end 52 of tubular sleeve 2 is attached to a flange 3 which has a first portion 54 and second portion 55 and which is provided with a closed loop transverse reinforcement member 7 which extends across the diameter of the flange 3. The flange 3 may be oval shaped, it may have a discontinuous surface forming spaces between a plurality of flange portions or tabs and it may be folded and packaged into a deployment sheath to facilitate delivery.

Description

Prosthesis The present invention concerns a prosthesis.

S Artificial prostheses consisting of a tubular conduit having an open lumen are well-known, and are used in medicine to replace diseased or damaged natural body lumens, such as, for example, blood vessels or other hollow organs such as bile ducts, sections of intestine or the like. Prostheses are also used to create vascular access to or between specific blood vessels and/or to connect an assist device, such as a ventricular assist device [VAD], to a vesseL The tubular conduit is generally formed of a blood impermeable material, and, to assist patency of the lumen, can be reinforced with a stent to form a stent-graft.

A stent can typically be of a mesh or lattice structure or a stent formed from wire can alternatively be used. The stent is often conveniently formed of a shape-memory material [such as nitinol) but could also be of other materials, for example stainless steel. A stent-graft can be used to treat aneurysms, where a section of natural blood vessel dilates and balloons outward. Aortic aneurysm is an example. The stent-graft is inserted within the diseased blood vessel to bridge across the aneurysmic portion. Endovascular delivery of a stent-graft has significantly improved treatment of aneurysm and patient prognosis.

Branched stents are known in the art for insertion at the junction of natural blood vessels and can be used to treat ostial stenosis. See for example WO 2007/130273, US 2008/0172123, and WO 2008/100297. Similarly, flanged stents for insertion into a branch vessel at its junction are known from JP 2004-298472 and US 2005/0049678. Typically, the stent is positioned so that the flange is flared to support the vessel branch point.

However, these stents are not formed with a graft sleeve and thus have limited utility.

Partially stented stent-grafts with a side branch are also known. See for example US 2010/0121429 which has a corrugated, but unstented, side branch.

However, in this device the corrugated unstented side branch is not fixed within the branch blood vessel.

S

Since patient anatomy is frequently complex it would be usefu' to have akernative forms of stent-graft prostheses able to support a natura' blood vesse' junction. It would be especially desirable to have a stent-graft prosthesis which can also be packaged for endovascular delivery.

A further challenge in vascular treatments is the provision of prostheses for end-to-side anastomosis. Such prostheses are typically attached to the side of an existing natural blood vessel [an artery or vein] or organ (for example, the heart] to divert blood-flow. An example is in the occlusion of large or medium bore arteries, such as abdominal aorta or iliac arteries) which require a by-pass graft to be attached to the side of the blood vessel to avoid an occluded portion. A further example is the connection of Left Ventricular Assist Devices [LVAD) to the heart and which require the outflow conduit to be connected to the side of the ascending aorta. Likewise a Right Ventricular Assist Device (RVAD] can require connection to the heart, with the outflow connection to the pu'monary artery. Other end-to-side anastomoses are usefu' to allow access to the heart) for exampk in minimally invasive (keyhole) surgery) for examp'e to connect the left atrium and subclavian artery.

Another example is in the use of a temporary access device to facilitate insertion of TAVI or TEVAR delivery systems) particularly where the iliac vessels are too small, tortuous or diseased to permit these arge delivery systems to pass. In such situations a graft conduit can be attached to the vesse' by suture to provide a arger access route. Once the procedure has been completed, the access graft conduit is simply cut short and sutured closed. It is essential to ensure robust attachment of the prosthesis, and traditionally such procedures require surgical intervention with attachment by suture.

Such branching prostheses are often formed with a large single flange to S facilitate attachment at an acute angle to the natural blood vessel, in order to increase the circumference of the graft available for attachment See for example DE 102007063266 and DE 102007063267.

An alternative structure is to produce a T-shaped graft such as described in io US 2004/0068277. However, this prosthesis requires the assembly and alignment of two cylindrical elements within the lumen of a blood vessel and is mechanically complex.

Prostheses adapted to provide connection in a substantially perpendicular manner are described in WO 00/09040 and WO 01/41653, of each which require the assembly of a separate element onto the prostheses and thus are mechanically complex. Alternatives rely on a radially projecting integral flange or gripping elements as described in US 2011/0071455 and WO 01/26562.

US 2011/0118763 and EP 1115352 each describe a T-shaped prosthesis to create a branch in an artery for by-pass. A stented main graft body sits within the lumen of the artery, with a neck or branch extending through the artery wall.

The stenting at each end of the main graft body is critical to hold the prosthesis in location.

Difficulties with end-to-side anastomosis persist For example, end-to-side connections generally require temporary cross-clamping of the vessel while the anastomosis is effected as well as significant time to suture the graft to the vessel to provide a blood tight seal. Clamping causes the target blood vessel to be temporarily excluded from blood flow, significantly increasing risk factors.

Additionally, in some cases, the access available for the surgeon to effect a circumferential suture line is limited due to the location of adjacent anatomy and/or the surgical approach required.

Improved prostheses for simple and effective end-to-side anastomosis would be beneficiaL In a first aspect) the present invention provides a stent-graft prosthesis comprising a tubular sleeve having a first end and a second end, and having an open lumen extending therethrough; a flange projecting radially outwardly from the sleeve; said flange having a first portion conjoined with the first end of the sleeve, and a second portion having a flange stent element attached thereto.

The flange is attached to the first end of the graft sleeve and extends outwardly therefrom. In some embodiments, the width of the flange can be of a size approximately equivalent to the diameter of the graft sleeve. For example the flange can have a width of 3mm to 50mm, for example 3mm to 20mm. Generally the flange may have an approximate surface width of value [flange outer width dimension F0 minus flange inner width dimension F1 I divided by 2 i.e. [F0 F]/2.

A stent graft prosthesis may be sized such that the lumen has a circular cross-section of diameter i. and the flange forms an annular surface of outer diameter 0po around the lumen, the annular surface of the flange having a surface area FA wherein Fp. [Tt (øFo/232 -ii [ØL/Z)21.

The flange may be of any convenient shape, but can conveniently have a rounded shape, for example can be substantially oval or circular.

When unconstrained, the flange is usually substantially planar. Once the stent-graft prosthesis is deployed, the flange will extend radially outwardly relative to the longitudinal axis of the lumen of the sleeve. In one embodiment the flange extends substantially perpendicularly to the axis of the lumen of the sleeve, for example, the flange may extend at an angle of 80 to 1000 relative to the axis of the lumen of the sleeve, optionally at an angle of 85 to 95° relative to the axis of the lumen of the sleeve, for example at an angle of 88 to 92° relative to the axis of S the sleeve. In another embodiment (for example to facilitate vascular access), the flange may extend outwardly at an angle of 40 to 60° relative to the longitudinal axis of the lumen of the sleeve) optionally at an angle of 45 to 55°.

The flange will normally be present around the entire circumference of the graft sleeve) but in some indications the flange only needs to be present around part of the graft sleeve circumference.

A stent graft prosthesis can have a flange comprising a discontinuous surface forming a plurality of flange portions or tabs, having space between the respective flange portions or tabs.

The flange can be formed of any suitable material and is conveniently formed of knitted or woven fabric, typically of ePTFE, PTFE, polyester, polyethylene or polypropylene. The flange can be formed from the same material as the graft sleeve or from a different material from the graft sleeve. The flange may optionally be coated to reduce friction, discourage clotting or to deliver a pharmaceutical agent Additionally, the fabric of the flange can be porous on one or both surfaces to enable cell ingrowth.

The flange can be formed separately to the sleeve and then attached thereto by any convenient means. For example the flange can be stitched or glued to the sleeve. Alternatively the flange and sleeve can be formed integrally with each other.

The second portion of the flange is supported by the flange stent element The flange stent element can be located substantially at the outer edge of the flange (that is the free edge located distant from the graft sleeve). To ensure robust attachment of the flange stent element, in some embodiments it may be necessary to have a small portion of the flange located beyond the flange stent element. This "free" portion of the flange will typically be from 1mm to 5mm.

S Thus the second portion of the flange will typically be a circumference of the flange ocated within 5mm of its outer edge. The flange stent element will extend around at least part of the second portion of the flange, for example will extend around at least 50% of the second portion, for example 60% or more of the second portion. In some embodiments the flange stent element will extend around substantially all of the second portion of the flange [for example 70% or more) 80% or more) optionally 90% or more) such as 95% or more) and may extend around the whole (i.e. 100%) of the second portion of the flange. Where the flange stent element extends around less than the whole of the second portion the flange stent element may comprise a number of stent elements (each iS supporting a segment of the second portion of the flange) which together form the flange stent element The flange stent element can be of any suitable stent configuration. Multiple stent configurations are known in the art or commercially available and suitable stent configurations will be known to those skilled in the art For example, where the flange stent e'ement extends around 90% of the circumference of the graft sleeve it may be in a NC-shaped" form. Alternative versions of stents, as known in the art) could also be used and non-limiting examples include Z-stents, zigzag stents, mesh stents, lattice stents and the like.

The flange stent element can be formed as a ring stent. The advantage of a ring stent configuration is that the stent extends around the whole of the circumference of the second portion of the flange and thus provides support around this wh6le circumference.

Optionally, the flange stent element is formed from a suitable resilient material, such as nitinol or PEEK. The flange stent element can be a ring stent extending around the whole of the second portion of the flange (for example at its outer edge) and formed from a single strand or from multiple windings of an elongate S resilient material, for example nitinol wire.

Once the stent-graft prosthesis is deployed, the flange stent element provides an outward bias on the flange, urging the flange to project radially outwardly from the sleeve. After deployment) the flange stent element exerts an outward force on the flange. The material used to form the flange is then under tension.

Optionally the tension is selected so that the material of the flange is held tautly.

Where the flange stent element is a ring stent, the inner circumference of the flange stent element is desirably substantially identical to (preferably identical to) the circumference of the second portion of the flange (i.e. its outer circumference excluding any "free" portion of the flange extending beyond the second portion). By "substantially identical to" we refer to a circumference which is equal to or up to 5% greater than the circumference of the second portion of the flange, preferably which is equal to or up to 2% greater than the circumference of the second portion of the flange, and more preferably equal to or up to 1% greater than the circumference of the second portion of the flange.

The flange stent element can be attached to the flange by any suitable means and may be located on either surface of the flange. One convenient form of attachment is by stitching the flange stent element to the flange, but other means of attachment such as the use of adhesive, heat bonding or sandwiching the stent element within two layers of the flange (for example within a hem of the flange) could also be used.

The flange stent element can be independently formed of any suitable biocompatible material having the necessary resilience to fold inwardly into a

B

first folded configuration (i.e. for packaging] and to adopt a second open configuration (i.e. after deployment]. Mention can be made of shape memory materials such as, for example, nitinol. Resilient polymers are also suitable, particularly engineering high modulus polymers such as polyetheretherketone S (PEEK]. PEEK polymer with shape memory behaviour can be used.

Optionally the flange stent element is formed from a continuous loop of resilient material (nitinol, PEEK or the like] in elongate form. The number of strands of elongate material (e.g. nitinol wire] used in forming the flange stent element can be varied according to the diameter of the elongate material utilised and the diameter of the flange second portion. The number of strands wound can vary from 1 to 120 or even more, but typically 2 to 30 strands is suitable. Any diameter of elongate material which maintains the required resilience can be used. Suitable diameters for the elongate material can be selected from a range of 0.1mm to 2mm, for example 0.1mm to 0.5mm. The ends of the elongate material can conveniently be closed off together.

The presence of the flange provides the sealing and anchoring between the stent-graft prosthesis of the present invention and the inner wall of the target vessel. The diameter of the stented flange should be large enough that, when placed into the target vessel, the deployed flange covers a significant arc of the target vessel wall when viewed in transverse cross-section. For example) the flange will extend around 45) or more of the target vessel wall circumference when viewed in transverse cross-section. In one embodiment the flange will extend around 60° or more, for example 90° or more or even 100°, 110° or 120° or more, for example 180°, 270° or even 360° of the target vessel wall circumference when viewed in transverse cross-section.

The stent-graft prosthesis of the present invention can be deployed using a catheter or other delivery system. The stent-graft prosthesis can be compacted, with the stented flange being folded into a compacted configuration for delivery.

One advantage of the stented flange in the prosthesis of the present invention is that it can be folded into a sinusoidal configuration which enables excellent packing characteristics whilst maintaining ease of deployment S In use, the prosthesis is partially advanced through an opening or fenestration in a body or organ vessel wall or in a [separate pre-deployed) prosthesis such that the flange is pressed against the wall surrounding the opening or fenestration on one side of the wall, with the sleeve extending through the opening or fenestration so that the remainder of the sleeve is located on the other side of the wall.

The sleeve can be formed from any suitable material, but would typically be a fabric (usually a knitted or woven fabric] of ePTFE, PTFE or polyester, polyethylene or polypropylene. The sleeve may optionally be coated to reduce friction, discourage clotting or to deliver a pharmaceutical agent The fabric can be porous on at least one surface to enable cell ingrowth. The sleeve may be of constant diameter, but could also be tapered. If tapered, the diameter of the sleeve could increase towards the first end or increase towards the second end.

Optionally, the prosthesis according to the invention can include a first stent element located at the first end of the sleeve. Typically, the first stent element, if present, will be at or close to the junction between the sleeve and the flange.

Optionally, the sleeve can include further stent elements along its length. As for the first stent element, the further stent elements are not limited to any particular configuration. One skilled in the art would be aware of a variety of stent element formats that could be used. Suitable stent elements could be spaced apart from each other and attached to the sleeve in a manner as described for the first stent element. Whilst the further stent elements could be simple ring stents, in some embodiments the use of a sinusoidal (saddle shaped) configuration may be of benefit to assist packaging. Inclusion of further stent elements can be beneficial in assisting the sleeve to adopt an open configuration along part of or the whole of its length, to facilitate adoption of a degree of curvature if required and/or to maintain the ability to seal well at one or both of its ends.

S

By "saddle shaped" we refer to a circular ring stent formed of a material which is sufficiently resilient to be distorted so that a first pair of diametrically opposed points on the circumference of the ring are displaced in one axial direction whilst a second pair of diametrically opposed points, centrally located on the circumference between the first pair, are displaced in the opposing axial direction to form a symmetrical saddle shape. The degree of axial displacement between the first pair of points and the second pair of points (which axial displacement is also termed the "saddle height"), is a function of the original circumference of the ring stent prior to its distortion relative to the final circumference of a circle within which the distorted configuration can be located.

Thus, the ratio of the final circumference: original circumference provides a simplistic notation of the axial displacement. Generally, the final circumference will be the outer circumference of the graft sleeve to which the stent is attached.

The percentage oversize of the undistorted inner circumference of the circular stent relative to the outer circumference of the graft sleeve also give a convenient measure of the saddle shape adopted, and can be calculated as: Oversize% = [Stent inner diameter-Graft sleeve outer diameterl x 100 Graft sleeve outer diameter The number of further stent elements attached to the graft sleeve is limited only by its length. Conveniently the stent elements can be attached spaced apart from each other at regular intervals. The spacing can be uniform between each stent element or could be irregular, for example could be progressive so that the spacing between each stent element increases on a gradual basis or decreases on a gradual basis. Suitable spacing between stent elements is typically from 2 to 10mm, for example, 4, 5, 6, 7 or 8mm. Spacing may be adjusted according to the diameter of the graft sleeve.

The prosthesis of the invention can be packaged for delivery by catheter.

S However, endovascular delivery is not an essential feature of the invention since the prosthesis is also simple and easy to use during open surgery.

Optionally, the stent-graft of the present invention can further include a transverse reinforcement member on the flange. The reinforcement member can extend from the first portion of the flange (that is the edge attached to the graft sleeve] to the second portion of the flange. Conveniently two such reinforcing members are located in diametrically opposing positions on the flange. Alternatively, a reinforcing member can extend generally across the diameter of the flange, deviating from the strict diameter to skirt around the lumen within the join between the first portion of the flange and the first end of the sleeve. In particular, the reinforcing member can extend from a first location on the second portion of the flange to a second location on the second portion of the flange wherein said first and second locations are diametrically opposed to each other. In this way the reinforcing member may provide opposed support wings within the flange, which are beneficial in deploying the flange suitably within a lumen of a main prosthesis in a body lumen. In such a use the reinforcing member "wings" may be beneficially axially aligned with the lumen to support the flange, for example, after deployment into a main fenestrated prosthesis.

The reinforcing member can be made from any suitable resilient reinforcing material, but conveniently can be formed from nitinol or PEEK, optionally in elongate form, wound as a single strand or as multiple strands in a continuous loop. The number of strands used in the loop can vary depending upon the size of elongate member required and the diameter of elongate material used. The number of strands can vary from 1 to 120 or even more, but typically 2 to 30 strands are suitable. Any diameter of elongate material which maintains the required resilience can be used. Suitable diameters for the elongate material can be selected from a range of 0.1mm to 2mm, for example 0.1mm to 0.5mm. The ends of the elongate material can conveniently be closed off together. The reinforcing member could alternatively be formed from sheet material, such as nitinol sheet Conveniently the reinforcing member could be laser-cut from the sheet material of about 0.1mm -0.5mm.

The reinforcing member can be beneficial in assisting alignment of the stent graft prosthesis during compaction and deployment. The reinforcing member can be especially advantageous when the stent-graft prosthesis is to be delivered by catheter.

As noted above, the prosthesis can optionally include a first stent element located out or close to the first end of the sleeve. The first stent element extends substantially around the first end of the sleeve, that is to say the first stent element extends around at least 90% of the circumference of the graft sleeve.

Optionally, the first stent element extends around at least 95% of the circumference of the graft sleeve. Conveniently, the first stent element extends around the whole of the circumference of the graft sleeve. The first stent element can be located around the outside surface of the graft sleeve or around the inside (luminal side) of the graft sleeve. The first stent element is located at the first end of the graft sleeve.

The first stent element can be of any suitable stent configuration. Multiple stent configurations are known in the art and suitable stent configurations will be known to those skilled in the art. For example, where the first stent element extends around 90% of the circumference of the graft sleeve it may be in a "C-shaped" form. Alternative versions of stents, as known in the art, could also be used and non-limiting examples include Z-stents, zigzag stents, mesh stents, lattice stents and the like.

The first stent element can be formed as a ring stent The advantage of a ring stent configuration is that the stent extends around the whole circumference of the sleeve at its first end and thus provides support around the whole S circumference of the sleeve at this location.

The first stent ekment can be formed from any suitable resilient material.

Nitinol or PEEK can conveniently be used. Optionally, the first stent element can be formed as a ring stent from multiple windings of a wire, for example nitin6l wire.

Once deployed, the first stent element provides an outward bias to the first end of the sleeve, urging the sleeve end into an open configuration to allow access (blood flow] into the lumen.

Where the first stent element is a ring stent and attached to the outer surface of the sleeve, the inner circumference of the first stent element is desirably substantially identical to (preferably identical to) the outer circumference of the graft sleeve. By "substantially identical to" we refer to a circumference which is equal to or up to 5% greater than the outer circumference of the graft skeve, preferaNy which is equal to or up to 2% greater than the outer circumference of the graft sleeve, and more preferably equal to or up to 1% greater than the outer circumference of the graft sleeve.

The first stent element can be attached to the graft s'eeve by any suitable means and may be located inside the graft sleeve (i.e. within the skeve umen) or exterior of the graft sleeve (i.e. on its outer surface]. One convenient form of attachment is by stitching the first stent element to the graft s'eeve, but other means of attachment such as the use of adhesive, heat bonding or sandwiching the stent element within two layers of the graft sleeve (for example within a hem of the graft sleeve) could also be used.

The first stent element can be termed a "terminal stent" since it is located at the first end of the graft sleeve.

S The first stent element can be independently formed of any suitable hiocompatible material having the necessary resilience to fold inwardly into a first folded configuration (i.e. for packaging] and to adopt a second open configuration (i.e. after dep'oyment]. Mention can be made of shape memory materia's such as, for example, nitinoL Resilient polymers are also suitable, particuaHy engineering high modulus polymers such as p6lyetheretherketone (PEEK). PEEK polymer with shape memory behaviour can be used.

Opt:ionally the first stent: element: can be formed as a ring st:ent: from a continuous loop of resilient material [nit:inol, PEEK or the like) in elongate form.

The number of strands of elongate material (for example nitincil wire) used in forming t:he first: stent element: can be varied according t:o the diamet:er of ftc elongate mat:erial utilised and the diamet:er of the sleeve lumen. The number of st:rands wound can vary from 2 to 120 or even more, but: typically 10 t:o 30 st:rands is suitable. Ally diamet:er elongat:e material which maint:ains the required resilience can be used. Suitable diameters for the elongate material can he selected from a range of 0.1mm to 2mm, for example 0.5mm to 1mm.

In a second aspect, the present invention provides a stent-graft prosthesis comprising a tubular sleeve having a first end and a second end, and having an open lumen extending therethrough; a flange able to project radially from the sleeve; said flange having a first portion conjoined with the first end of the sleeve, and a second portion having a flange stent ekment attached thereto) and a reinforcing member which extends across at least one radius of said flange.

Optionally a first stent member is attached to said sleeve at the first end thereof.

The present invention also provides a catheter loaded with a stent-graft prosthesis according to the first or second aspects described above.

In another aspect, the present invention provides a stent-graft prosthesis S comprising a tubular sleeve having a first resilient outwardly biased ring stent element attached to one end thereof and having a flange attached to said one end thereof said flange comprising a second resilient outwardly biased stent element in the form of a ring stent which when unconstrained urges the flange into a substantially planar configuration. The second resilient outwardly biased stent element may be spaced from the outer edge of the flange. The spacing from the outer edge of the flange may be at least 1 mm and up to 5 mm or more from the outer edge of the flange.

In a further aspect the present invention provides a method of creating an end-to-side connection with a hollow vessel or organ of the patient, said method comprising inserting a stent-graft prosthesis as described above such that the flange is located inside the vessel or organ and the sleeve extends through an opening in the wall of the vessel or organ and the remainder of said sleeve is located outside the vessel or organ.

In a further aspect the present invention provides a method of forming a branch in a fenestrated prosthesis) said method comprising inserting a stent-graft prosthesis as described above such that the flange is located inside the fenestrated prosthesis and the sleeve extends through the fenestration and the remainder of said sleeve is located outside the fenestrated prosthesis.

The above method can be used in treatment of aneurysm, for example aortic aneurysm. The method can also be useful in construction of a by-pass, such as arterial or coronary by-pass.

Preferred or alternative features of each aspect or embodiment of the invention apply mutatis mutandis to each other aspect or embodiment of the invention) unless the context demands otherwise.

S The present invention will now be further described with reference to the foflowing figures, in which: Figure 1 is a schematic illustration of a stent-graft prosthesis of the present invention in deployed form as a branch prosthesis after deployment into a main fenestrated prosthesis; Figures 2a, 2b, 2c show respectively side views of embodiments of the stent-graft prosthesis of Figure 1, with differing sizes of flange, when deployed in a target vessel; and Figures 3a and 3b show by way of a schematic illustration how a flange ring stent element of the stent-graft prosthesis of the present invention may be compactly folded for delivery in a deployment sheath; Figure 1 shows a stent-graft prosthesis 1 according to the present invention in deployed form. As illustrated, the prosthesis 1 comprises a tubular sleeve 2 having a first end 52 and a second end 53 and a lumen 4 which extends between the first and second ends 52, 53. The prosthesis 1 is formed from any suitable biocompatible material, but can conveniently be formed from woven polyester.

The sleeve 2 is supported by a number of spaced ring stents 5 which are attached to the outer diameter of sleeve 2 by any convenient means) for example by stitching. In an alternative form the ring stents 5 could be attached to the inside surface of sleeve 2. The ring stents S can be formed from any suitably resilient material which maintains the patency of lumen 4. Optionally, the ring stents S could be replaced by alternative stent forms. Mention may be made of zigzag, Z-stent, or Gianturco stents. As illustrated in Figure 1, sleeve 2 is stented along the whole of its length, but it is also possible for sleeve 2 to contain unstented sections. A first stent element 8 is located at the first end 52 of the sleeve 2 and is illustrated as a ring stent although other types of stent are also possible. First stent 8 as illustrated is a ring stent formed from multiple S windings of nitinol wire and is attached by stitching. Once deployed, the stents 5, 8 urge the sleeve to adopt an open configuration. Indicia line 9 is induded to facilitate insertion of the stent-graft prosthesis 1 without twists in sleeve 2.

Indicia line 9 can be a coloured thread woven or sewn along the length of sleeve 2 as is known in the art.

The first end 52 of sleeve 2 is attached to a flange 3 which has a first portion 54 and a second portion 55. In its deployed form as illustrated flange 3 extends radially outwardly from the axis of sleeve 2. The first portion 54 of flange 3 can he conveniently attached to the first end 52 of sleeve 2 by stitching, but other iS types of attachment can be used or the flange could be formed integrally with the sleeve 2. A flange stent element 6 is located at the second portion 55 of flange 3 at or close to the outer circumference of flange 3. A small margin of flange (forming a free portion of the flange 3] extends beyond the location of flange stent 6. As illustrated flange stent 6 is a ring stent and extends around the whole circumference of the second portion 55 of flange 3. However, in alternative embodiments, it is also possiNe for the second portion 55 of flange 3 to be supported on only some locations around its circumference. In such embodiments, flange stent ekment 6 would be C-shaped or would be composed of a number of stent elements, each extending around a segment of the second portion 55 of flange 3. Flange 3 can be comprised of any suitable biocompatible, flexifrie material. Mention maybe made of ePTFE, PTFE, polyester) polyethylene or polypropylene. Figure 1 also illustrates that in this embodiment flange 3 is substantially circular and, in its unconstrained form, is substantially planar. In the embodiment shown in Figure 1, a transverse reinforcement member 7 extends across the diameter of flange 3. As illustrated, the transverse reinforcement member 7 consists of a closed loop which skirts around the junction with sleeve 2 and extends to the second portion 55 of flange 3. The transverse reinforcement member 7 can conveniently be formed from a resilient material such as nitinol or PEEK in elongate form) and is conveniently formed from a single strand elongate material or multiple windings of elongate material, S for example from 2 to 20 strands of nitinol wire having a diameter of 0.1 to 0.5mm.

The flange stent element 6 can also be formed from a resilient outwardly biased material, for example is formed from a single strand of elongate material or multiple windings of elongate material, such as nitinol wire. For example, stent element 6 can comprise from ito 20 strands of nitinol wire having a diameter of 0.1 to 0.5mm.

The flange 3 can be easily folded and packaged into a relatively small volume to facilitate delivery. This is illustrated by the embodiments, illustrated in Figures 3a and 3b where it is demonstrated how different sized flange ring stent elements 6, 6' of the stent-graft prosthesis of the present invention may be compactly folded for delivery in a deployment sheath 36. The flange ring stent elements 6, 6 of the stent-graft prosthesis fold to provide peak and valley portions.

Once placed within an opening of a natural blood vessel or prosthesis) flange 3 springs resiliently outwardly and presses against the internal surface of the blood vessel wall. As demonstrated in Figures 2a, 2b, 2c, the size of flange 3 may be selected such that it extends around at least a part of the inner circumference of the blood vessel/prosthesis wall when viewed in transverse section.

Conveniently, however, the flange 3 may extend around at least 900, preferably more than 90° of the inner circumference of the target vessel/prosthesis wall when viewed in transverse section, for example will cover 1000 or more) such as 105°, 1100, 120° or even more. In alternative embodiments the flange will extend around less than 900 of the inner circumference of the target vessel, for example 450 to less than 900, for example 69° to less than 900, The benefit of the transverse reinforcement member 7 illustrated in Figure 1 is S that it allows compaction of the flange 3 within a delivery system during deployment, but after release provides a high degree of stability of the deployed flange 3 and axial alignment to the target vessel.

Figure 2 illustrates the deployed stent-graft prosthesis 1 when located within a blood vessel or prosthesis 10 which is cut transversely and viewed from the cut cross-section along the lumen of blood vessel or prosthesis wall adjacent the locaUon where prosthesis 1 has been deployed. Flange 3 extends around the inner circumference of he blood vessel/prosthesis wall 10 and in this embodiment flange 3 covers a lease 900 of that circumference. is

Figures 3a and 3b show alternaUve embodiments of the sen-graft prosthesis 1 according o the present invenUon. These have differing sizes of flange ring sen element As in the embodiment of Figure 1, the prosthesis 1 comprises a sleeve 2 having an open lumen 4 extending from the first end S2 to a second end 53. At the first end 52 a flange 3 is attached and is shown projecting radially outwarcfly from skeve 2. The prosthesis 1 comprises a first stent 8 in the form of ring stent at its junction with flange 3. As illustrated, once deployed) flange 3 is substantially circular and, in the deployed form ifiustrated, substantially planar. As illustrated) the sleeve 2 is supported by spaced ring stents S along its length. These ring stents S adopt a more saddle shaped form progressing towards the first end 52 of the sleeve 2. The stents S are shown attached to the outer surface of the sleeve 2 by stitching but alternative forms could also be used. The sleeve 2 can be formed from any knitted or woven biocompatible material.

Flange 3 includes a second resilient outwardly biased flange stent element 6 which extends around the second portion 55 of flange 3. As illustrated, flange stent element 6 extends around the whole of the outer circumference of flange 3, but it is also possible that portions of the second portion 55 of flange 3 are not supported in this way.

Figure 1 illustrates the stent-graft prosthesis 1, which may be any embodiment such as those of Figures 3a, 3b, and 3c, deployed as a branch prosthesis in a main prosthesis 10 having a fenestration 11 in the sidewall 12 thereof.

Suitable applications include the treatment of thoracic aortic aneurysm in the location of the renal arteries, where the fenestration 11 is to be aligned with a natural blood vessel, for example a renal artery. After deployment of the main prosthesis 10 and optionally after creation of the fenestration 11 in situ (if the main prosthesis 10 does not include a pre-formed fenestration 11, the prosthesis 1 according to the invention will be partially advanced through the fenestration 11 and deployed. Depending upon the location of deployment of the main prosthesis 10, the prosthesis 1 of the invention could be advanced through the lumen of the main prosthesis 10 or could be advanced through the natural side branch blood vessel. Figure 1 shows the prosthesis 1 according to the invention in fully deployed form, with the flange 3 (shown in dotted outline) located in the lumen of the main prosthesis 10 and expanded such that flange 3 presses against the inner wall of the main prosthesis 10, thereby sealing the fenestration 11.

Blood flow from the lumen of the main prosthesis 10 through to the lumen 4 of sleeve 2 can proceed without interference.

The prosthesis according to the invention can be inserted via a catheter from inside the main prosthesis 10 or alternatively, if access is available, can be deployed by catheter from the natural branch vessel.

Claims

Claims: 1. A stent-graft prosthesis comprising a tubular sleeve having a first end and a second end, and having an open umen extending therethrough; a flange projecting radially outwardly from the sleeve; said flange having a first portion conjoined with the first end of the sleeve, and a second portion having a flange stent element attached thereto.
2. A stent graft prosthesis as claimed in claim 1, wherein the flange is attached to the first end of the graft s'eeve and extends outwardly therefrom.
3. A stent graft prosthesis as claimed in claim 1 or claim 2, wherein the flange has a surface width of value [flange outer width dimension F minus flange inner width dimension FI divided by 2 i.e. (F0 F1)/2.
4. A stent graft prosthesis as claimed in claim 3, wherein the flange inner width dimension is at least 3 mm.
5. A stent graft prosthesis as claimed in claim 3, wherein the flange outer width dimension is up to about 50 mm.
6. A stent graft prosthesis as claimed in claim 3, wherein the flange outer width dimension is up to about 40 mm.
7. A stent graft prosthesis as claimed in claim 3, wherein the flange outer width dimension is up to about 30 mm.
8. A stent graft prosthesis as claimed in claim 3, wherein the flange outer width dimension is up to about 20 mm.
9. A stent graft prosthesis as claimed in any one of the preceding claims wherein the flange is of oval shape.
10. A stent graft prosthesis as claimed in any one of claims 1 to 8, wherein the lumen has a circular cross-section of diameter øi. and the flange forms an annular surface of outer diameter øv, around the umen, the annular surface of the flange having a surface area FA wherein FA [it (v/2]2 -it (ø1j2]2].
11. A stent graft prosthesis as claimed in any one of claims 1 to 10, wherein the flange comprises a discontinuous surface forming a plurality of flange portions or tabs, having space between the respective flange portions or tabs.
12. A stent graft prosthesis as claimed in any one of claims 1 to 11, wherein the flange extends substantially perpendicularly to the axis of the lumen of the sleeve.
13. A stent graft prosthesis as claimed in any one of claims 1 to 11, wherein the flange extends at an angle of 80 to 1000 relative to the axis of the lumen of the sleeve, optionally at an angle of 85 to 95° relative to the axis of the lumen of the sleeve, for example at an angle of 88 to 92° relative to the axis of the sleeve.
14. A stent graft prosthesis as claimed in any one of claims 1 to 11, wherein the flange extends outwardly at an angle of 40 to 600 relative to the longitudinal axis of the lumen of the sleeve, optionallyatan angle of4S to 55°.
15. A stent graft prosthesis as claimed in any one of claims 1 to 14, wherein the second portion of the flange is supported by the flange stent element, and the flange stent element is positioned at an outer edge of the flange.
16. A stent graft prosthesis as claimed in claim 15, wherein a portion of the flange extends beyond the flange stent element
17. A stent graft prosthesis as claimed in claim 16, wherein the portion of the flange that extends beyond the flange stent element has a width dimension in the range of from ito 5mm as measured from an outer edge of the flange.
18. A stent graft prosthesis as claimed in any one of claims 1 to 17 wherein the flange stent element extends around at least part of the second portion of the flange.
19. A stent graft prosthesis as claimed in claim 18, wherein the flange stent element extends around at least 50% of the second portion.
20. A stent graft prosthesis as claimed in claim 18, wherein the flange stent element comprises a ring stent.
21. A stent graft prosthesis as claimed in claim 20, wherein the inner circumference of the flange stent element is substantially identical to the S supported circumference of the second portion of the flange.
22. A stent graft prosthesis as claimed in any one of the preceding claims wherein the flange stent element is formed from a continuous loop of resilient material in elongate form.
23. A stent graft prosthesis as claimed in claim 22, wherein a number of strands of elongate material (e.g. nitinol wire] are used in forming the flange stent element; the number of strands wound being from ito 120 or even more.
24. A stent graft prosthesis as claimed in claim 23 wherein, the diameters for the strands of elongate resilient material are selected from a range of 0.1mm to 2mm, for example 0.1mm to 0.5mm.
25. A stent graft prosthesis as claimed in any one of the preceding claims wherein the flange comprises a transverse reinforcement member selected from the group consisting of a reinforcement member extending from the first portion of the flange to the second portion of the flange, a pair of opposed reinforcement members extending from the first portion of the flange to the second portion of the flange, and a reinforcing member extending across the diameter of the flange.
26. A stent graft prosthesis as claimed in claim 25, wherein the flange comprises a physiologically benign material that is the same as the material of the tubular sleeve or different therefrom.
27. A stent-graft prosthesis comprising a tubular sleeve having a first end and a second end, and having an open lumen extending therethrough; a flange able to project radially from the sleeve; said flange having a first portion conjoined with the first end of the sleeve, and a second portion having a flange stent element: attached thereto, and a reinforcing member which extends across at least one radius of said flange.
28. A catheter loaded with a stent-graft prosthesis according to any one of the preceding claims.
29. A stent-graft prosthesis comprising a tubular sleeve having a first resilient outwardly biased ring stent element attached to one end thereof and having a flange attached to said one end thereof, said flange comprising a second resilient outwardly biased stent element in the form of a ring stent.
30. A stent graft prosthesis as claimed in claim 29, wherein the flange has an outer edge and the second resilient outwardly biased stent element is spaced from the outer edge of the flange.
31. A method of creating an end-to-side connection with a hollow vessel or organ of a patient, said method comprising inserting a stent-graft prosthesis as claimed in any one of the preceding claims such that the flange is located inside the vessel or organ and a part of the sleeve extends through an opening in the wall of the vessel or organ and the remainder of said sleeve is located outside the vessel or organ.
32. A method of forming a branch in a fenestrated prosthesis, said method comprising inserting a stent graft prosthesis as claimed in any one of claims 1 to 30, such that the flange is located inside the fenestrated prosthesis and a part of the sleeve extends through the fenestration and the remainder of said sleeve is located outside the fenestrated prosthesis.
33. A method of treatment of aneurysm, for example aortic aneurysm comprising delivering a stent graft prosthesis as claimed in any one of claims 1 to 29 to the site of a fenestrated prosthesis having a lumen, introducing the stent graft prosthesis to the fenestrated prosthesis, either through the fenestration via a natural side branch blood vessel or through the lumen of the fenestrated prosthesis, partially advancing the stent graft prosthesis through the fenestration and deploying the stent graft prosthesis such that the flange when located in the lumen of the main prosthesis is expanded to press against the inner wall of the main prosthesis, thereby sealing the fenestration.
34. A method as claimed in dlaim 33 comprising deployment of the stent graft S prosthesis via a catheter from inside the fenestrated prosthesis or by catheter from a natural branch vessel.
35. A by-pass construction procedure, such as arterial or coronary by-pass, comprising a method as claimed in claim 33 or claim 34.
36. A flanged prosthesis substantially as hereinbefore described with reference to and as shown in Figs. 1 and 2, or Figs. 3 and 4 of the accompanying drawings.