GB2517401A - Graft with moveable fenestration - Google Patents

Abstract

A prosthesis 1 has a tubular sleeve 10 with a movable fenestration zone in the side wall, comprising a fenestration 2 with a peripheral support 3, a planar portion 4 extending around the fenestration and supported by resilient member 6, and a second portion 9 extending from around the outer edge of the planar portion to the main sleeve 10 at junction 5. The fenestration zone is movable due to the second portion acting as an invertible collar for the fenestration, which may adopt an outwardly everted, neutral or inverted configuration (see figure 2). The resilient support 6 may be a ring with spring sections 20, 21, 22 to facilitate tensioning of the planar member. The supports may be made from nitinol or PEEK.

Description

GRAFT WITH MOVEABLE FENESTRATION

The present invention relates to a prosthetic graft and in particular to a fenestrated prosthetic graft for deployment by endovascular delivery.

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 for example bile ducts, sections of intestine or the like. One common use of such artificial prostheses is to replace diseased or damaged blood vessels.

A number ofvascuar disorders can be treated by use of an artificial prosthesis. One relatively common vascular disorder is an aneurysm. Aneurysm occurs when a section of natural blood vessel wall, typically of the aortic artery, dilates and balloons outwardly. Whilst small aneurysms may cause little or no symptoms, larger aneurysms or saccular aneurysms may pose a significant danger to a patient Rupture of an aortic aneurysm can occur without warning and is usually fatal, so significant emphasis is placed on early diagnosis and treatment With an increasingly ageing population, the incidence of aneurysm continues to rise in western societies.

Provided that an aneurysm is diagnosed prior to rupture) surgical treatment to repair the affected vessel wall is effective. Surgical treatment of aneurysm involves the replacement or reinforcement of the aneurismal section of aorta with a synthetic graft or prosthesis. This procedure requires general anaesthesia of the patient so that the patient's abdomen or thorax can be opened [see Parodi et al., Annals of Vascular Surgery (1991) 5:491-499]. Following surgical treatment, the patient will then have a normal life expectancy.

Surgical repair of aneurysm is however a major and invasive undertaking and there has been much effort in developing less invasive methods. Currently, aneurysm repair generally involves the delivery by catheter of a fabric or ePTFE graft which is retained at the required location by deployment of metallic devices (stents). The ability to deliver the stent-graft device by catheter reduces the surgical intervention to a small cut-down to expose the femoral artery and, in suitable circumstances, the device can be deployed percutaneously. Catheter delivery is beneficial since the reduced invasive nature of the procedure aflows utilisation of a local anaesthetic and leads to reduced mortality and morbidity) as well as decreased recovery time.

For example, endovascular repair is typically used for repair of infra-renal abdominal aortic aneurysms where the graft is placed below the renal arteries.

Many different types of devices useful for endovascular repair are now available, for example a resiliently engaging endovascular element described in US 6,635,080 (Vascutek) or a tubular fabric liner having a radially expandable supporting frame and a radiopaque marker element stitched to the liner as disclosed in US 6,203,568 (Medtronic).

However, whilst the endovascular repair of aneurysms is now accepted as the method of choice, the technique has significant limitations and is not suitable for all patients.

One successful type of prosthesis consists of a stent graft comprising a conduit formed of a flexible sleeve attached to a rigid support or stent. The sleeve will typically be made of a fabric (usually a knitted or woven fabric) of ePTFE, PTFE, polyester; polyethylene or polypropylene and may optionally be coated to reduce friction; discourage clotting or to deliver a pharmaceutical agent. The fabric will generally be porous on at least one surface to enable cell ingrowth. The stent may be balloon-expandable (e.g. a PALMAZ stent made of rigid stainless steel wire), but could also be self-expandable and formed of a shape memory material, such as nitinol (a nickel-titanium alloy). Numerous different stent designs are known in the art (see for example braided stents described in EP 880949 or wire zig-zag stents described in US 4580568).

Bifurcated stent graft prostheses are known in the art for treatment of abdominal aortic aneurysm at the lower end of the aorta close to its bifurcation into the left and right iliac arteries. The bifurcated stent graft used to treat an aneurysm at this location typically comprises a main body portion located in the aorta which extends across the aneurysm so that it can be fixed in place by expansion of a stent onto healthy aortic wall proximal to the aneurysm. The main portion of the graft divides into two smaller legs, each leg extending down one of the iliac arteries with the distal end of each leg also being fixed by expansion of a stent. For ease of deployment, a leg can be created by use of a separate leg extension with graft assembly occurring in vivo. See EP 1063945 and US 5676696.

Depending on the location of an aneurysm, the graft can be adapted to suit the location necessary. For example, where an aneurysm extends down an iliac artery, the graft can include a further arm directed to an internal artery of the iliac artery as described in WU 2007/124053. Alternatively, where the graft is to be located to span across the junction of an intersection (e.g. with the renal arteries), the graft can include an opening (fenestration) for alignment with one of the branch vessel(s) (see for example WO 99/29262 or EP 1673038). However, to date such fenestrated grafts must be individually designed for each patient since the anatomy of the vessel branches can vary significantly.

Production of unique, individually designed and manufactured endografts having appropriately located fenestrations which match the patient's individual anatomy requires meticulous design based on accurate pre-operative imaging data. The use of patient-specific designed grafts is expensive and requires significant pre-planning so that such grafts are not available in emergency situations. Moreover, the technical difficulties of aligning the or each fenestration to the branch vessel are significant, requiring precise axial and rotational control of the graft. No adjustments to the graft are possible during deployment, so that any errors in the initial diagnostic imaging or any changes in anatomy from the imaging stages cannot be rectified. An alternative approach requires the deliberate coverage of the branch vessel, which is clearly undesirable.

EP 2420206 describes a fenestrated stent graft where the fenestration is pivotable.

The fenestration is located in a band of material extending radially outwarthy from the prosthesis and narrowing in a cone-shape to the fenestration. A support frame can be present on or at the periphery of this band of material and requires a radial dimension to form the cone-shape. However, the cone-shape requires careful alignment at the branch vesse' to ensure that the branch vessel is located within the cone. If the cone is everted the cone shape may be pressed against the luminal wall of the body vessel, thereby impeding further movement of the prosthesis and/or of the cone. The support frame reduces the degree to which the fenestration can pivot.

There continues to be a need for a further and improved graft suitable for deployment at or near a vessel intersection, which is suitable for a range of patient anatomy and which avoids both the requirement for individual design and in vivo fenestration.

The requirement for such fenestrated grafts can apply to any vessel intersection, including without limitation, the renal arteries, mesenteric artery, brachiocephalic artery, carotid arteries or left subclavian artery. Graft fenestration design is particularly difficult in locations where two or more intersections are located within the length of the graft.

The present invention provides a prosthesis comprising a tubular graft sleeve of a biocompatible material having an aperture in a side wall of the tubular graft sleeve, wherein said graft s'eeve is provided with a moveable fenestration zone associated with the aperture, said fenestration zone comprising iJ a first portion which is planar, and is fenestrated; ii) a flexible second portion connecting the first portion with the graft sleeve, and iii) a resilient member connected to the first portion; wherein the first portion is of greater size than the aperture, the second portion is

S

connected around the aperture, and the resilient member acts to maintain planarity of the first portion.

In such a prosthesis, the fenestrated planar portion is "oversize" with respect to the aperture in the side wall of the tubular graft sleeve. The connecting second portion thereby tends to adopt an acute angular disposition with respect to the planar portion. This permits the planar portion to be flattened and overlie the aperture in one configuration. The flexible nature of the connecting second portion a'so permits lateral movement of the phnar portion with respect to the aperture.

In embodiments, the aperture in the graft s'eeve may be, at least in part, a curved shape, for examp'e elliptical i.e. ova', or circular. The phnar portion may be of a complementary shape the longest dimension of which exceeds the corresponding longest dimension of the aperture.

The fenestration in the planar first portion may be of any suitable shape and is typically also elliptical, but smaller than the aperture in the graft sleeve, and sized to correspond sufficiently with a branch vessel when aligned therewith in the intended use.

An advantage of this prosthesis is that the configuration described here provides a low profile adjustable fenestration zone. The low profile is achievable by the increase in size (e.g. diameter) from that measured at the tubular graft sleeve junction with the second portion, with that measured at the junction of the second portion with the planar portion, and maintainable by the support provided by the resilient member. This permits the second portion to be hid substantially flat against the tubular graft sleeve, bringing the planar first portion into close proximity with the tubular graft sleeve and permitting the Thw proffie of the fenestration zone as a whok.

Additionally, the resilient member, which is preferably located at the periphery of the first portion, provides definition to the perimeter of the first portion and aids dimeisional stabilky of the first portion, and also introduces sufficient tension into the planar first portion to provide that the fenestration therein is on a flat, un-rucked material surface.

Furthermore, the presence of the resilient member also tensions the second portion) which as a consequence allows the planar first portion, and second portion to lay flat with the underlying surface of the tubular graft sleeve when no external force is applied to the fenestration zone.

The second portion) which spans between the boundary of the aperture in the side wail of the tubular graft sleeve and the outer perimeter of the first planar portion) enables the planar portion to slide transversely in the plane of the planar portion.

Thus in addition to an ability to move laterally relative to the side wall of the graft sleeve, the planar portion can be located flush with the side-wall of the graft sleeve and can slide in any direction (in a manner that remains flush with the side-wall] so that the location of the fenestration can be adjusted to any point within the fenestration zone, but without the need to have an externally protruding portion extending outwardly from the graft side-wall.

The term "fenestration" is defined herein as a hole or opening within a surface of a graft sleeve or prosthesis [for example in the sidewall of the graft sleeve or prosthesis) or to the process of producing such a hole or opening. The fenestration can have any shape including, but not limited to) rectangular, triangular or curvilinear (e.g. circular, oval or the like). The fenestration allows fluid communication between the exterior of the graft and the lumen of the graft, and thus allows fluid communication from the graft lumen to any branch vessel.

As in the embodiments described in this disclosure a "fenestration" may comprise more than one opening in respective parts which are juxtaposed to overlie in use, such that a common opening is accessible to a lumen in a vessel. In the embodiments herein an opening in the outer, movable planar first portion of the fenestration zone is referred to as a "fenestration". As noted above the underlying "aperture" in the graft tubular graft sleeve could also be referred to as a fenestration, since it also allows access to a lumen in a vessel. However, for clarity reasons, only the opening(s) in the moveable planar first portion, which is designed to correspond with a lumen of a branch vessel in use, is referred to as a "fenestration" in description of embodiments in this disclosure.

Optionally each such opening, aperture or "fenestration" can be bounded by a strand of resilient material) for example nitinol wire or a strand of polyether ether ketone (PEEK). The strand of resilient material can be sewn around the circumference of the fenestration so that the fenestration is kept open and also so that the edges of the material around the fenestration are prevented from fraying.

The tubular graft sleeve can be formed from any biocompatible material which is sufficiently flexible or compliant to be useful in the intended use. The graft sleeve is usually formed of a woven or knitted fabric. The sleeve will usually be substantially impervious to fluid, especially physiological fluids. Optionally, at least one surface of the sleeve will be sufficiently porous to facilitate cell ingrowth. Suitable materials include polyester, polyurethane, polyethylene, polypropylene, ePTFE, PTFE and the like.

The tubular graft sleeve can be coated to reduce permeability or to deliver a biological agent The tubular graft sleeve forms the side walls of the main body portion of the graft If the requirement is for a graft which is a bifurcated graft, the tubular graft sleeve may also form at least part of a wall of the first leg and/or the second leg after bifurcation.

For many intended purposes, the tubular graft sleeve can conveniently be formed with a constant diameter. However tapered grafts (i.e. where the diameter varies along its length) are also possible and are particularly useful for certain indications.

The diameter of the graft may however vary in the fenestration zone as is described bel ow.

B

The fenestration zone can be formed using a fabric insert or could be formed integrally as part of the graft sleeve. The fenestration is located in the first planar portion of the fenestration zone. The planar portion can be of any suitable shape, but preferably is circu'ar or substantially circular.

In a contemplated use in a vessel, the fenestration zone, being of a mobile construction, may be inverted into the lumen of the tubular graft sleeve, which action removes the planar first portion away from the wall of the vesse' in proximity to the tubular graft sleeve thereby avoiding that planar first portion being dragged across the vesse' wall. This is significant because it provides for a gap between the fenestration zone and the vessel wall, permitting catheter manipulation to aid cannulation.

The planar portion and second portion can be joined from a single piece of material or could be formed from separate pieces of material joined together by suitable means. The interface between the planar portion and second portion can conveniently be defined by the resilient member.

The combination of the first planar portion, the second portion and the resilient member enables the profile of the fenestration zone to be reduced, whilst maintaining the ability for fenestration movement within the fenestration zone. A low profile for the fenestration zone is beneficial since blood flow reduction through the sleeve lumen is minimised.

In one embodiment, the second portion is tubular or is substantially tubular of uniform cross-section. The second portion can akernatively be tapered. The second portion is usually formed from a flexilMe biocompatible material. The fenestration zone can be formed from the same biocompatible material as the tubular graft sleeve. A first end of the tubular protruding (second) portion is attached to the outer periphery of the planar Iirst portion, for example by adhesive, heat bonding or sewing. The second end of the tubular protruding (second) portion can be attached to the tubular graft sleeve, again for example by adhesive, heat bonding or sewing.

In longitudinal cross-section, the fenestration zone will appear substantially U-shaped.

Advantageously the planar first portion includes a resilient support member generally located at the outer edge of the planar first portion. As noted above, the resilient support member may be for example, at least a strand of resilient material.

Suitable resilient materials include nitinol wire or a strand of polyether ether ketone (PEEK). The strand of resilient material can be sewn around the outer circumference of the planar portion) for example at its junction with the second portion. The inclusion of a resilient support member on the planar portion prevents the planar portion inadvertently covering the fenestration and blocking access.

The resilient support member may be engineered to have functional parts to influence performance of the planar portion of the fenestration zone. Portions of the support member may be looped or coiled to form resilient portions which may be weaker or less stiff than other portions of the support member. These portions would be less rigid than the other parts of the support member, and thus accommodate and facilitate movement of the fenestration zone whilst tending to restore overall fenestration zone shape and tension in the planar first portion after a displacing force is removed. These resilient portions of the support member contribute functional benefits with minimal volume impact The resilient support member tensions the fabric of the planar first portion preventing the fabric from covering the fenestration. Additionally, the resilient support member gives definition to the boundaries of the planar first portion and urges the planar first portion to maintain its intended shape and configuration e.g. by holding the intended diameter. This diameter is larger than the diameter of the junction point between the second portion and the graft sleeve.

This relation between the diameters contributes significantly to the general flattening of the configuration of the fenestration zone when not subjected to an external force.

In embodiments where these diameters were identical, it would be possible for the fenestration zone to extend outwardly from the tubular graft sleeve wall by the full length of the second portion. With the preferred larger diameter of the planar first portion the second portion is forced to assume an acute angle to meet the planar portion. This effectively decreases the depth of the fenestration zone significantly i.e. distance or spacing with respect to the apertured side wall of the tubular graft sleeve. The presence of the resilient support member is also significant because in a construction lacking that support) the diameter of the planar first portion would not be maintainable in the flexible fabric of the first portion and the flattened low profile nature of the fenestration zone would not be achievable.

Conveniently the resilient support member is located at the periphery of the planar portion remote from the fenestration. Optionally, the resilient support member describes the outer edge of the planar portion. Optionally, the resilient support member can include one, or more functional biasing "give points" able to absorb movement of the fenestration zone whilst maintaining the overall fenestration zone shape and tension with minimal volume impact These bias points may be formed by loops or curved spring portions of the support member. Where two or more such bias points are present, these can advantageously be spaced equidistantly around the outer edge of the planar portion. Two, three or four equidistantly spaced bias points can be present, although the invention could also include five or six or even more. The biased weak points could be a portion of the support member able to provide a variation in tension around the edge of the planar portion. For example, the biased weak point could be a spring section, for example formed from a zig-zag portion of the resilient support member. Figure 5 illustrates a resilient support member having four equidistantly spaced biased weak points each formed as zig-zag spring sections.

The advantage associated with the presence of the bias points can be developed by ensuring that the support member at these bias points is not fully constrained (e.g by omitting stitching or bonding adjacent to the bias points) on the planar portion 1l and so are allowed to deform under applied force. The remaining resilient portions of the resilient support member will retain the tensioning requirement on the planar first portion.

The inclusion of the resilient support member around the outer boundary of the planar portion is beneficial since the planar portion can be formed so that the fabric is under sufficient tension to be smooth (unwrinkled), maintaining a planar shape.

This also has the advantage that the fenestration is presented for cannulation on smooth, tensioned fabric which aids insertion of the cannula. Conveniently the fenestration is located centrally within the first planar portion, so that an area of the planar portion extends all around the fenestration. As a consequence the likelihood of the fenestration becoming partially blocked or even covered by fabric (for example from fabric forming the second portion] is advantageously much reduced.

Alternatively or additionally the second portion includes a support member, for example, the support member can be a strand of resilient material, for example nitinol wire or a strand of PEEK. The strand of resilient material can be sewn around the circumference of the second portion, for example at or adjacent its junction with the planar portion. Alternatively or additionally the support member attached to the second portion can be a tubular mesh or zig-zag stent, typically of a biocompatible metal such as nitinol.

In an alternative aspect, the present invention provides a prosthesis comprising a graft sleeve having a first end and a second end, with a lumen extending therethrough from the first end to the second end, wherein said graft sleeve comprises a fenestration zone having a planar portion which is fenestrated and a second portion located between said graft sleeve and said planar portion. The fenestration zone may by this construction have alternative inverted and everted configurations with respect to the graft sleeve, in which respective configurations the second portion extends into the lumen, and outwardly from the graft sleeve.

Generally, the prosthesis is inserted into a main vessel of the patients body so that the fenestration maybe aligned with an intersection to a branch vessel to allow fluid flow thereto.

Optionally, the prosthesis according to the present invention includes two fenestration zones as described above. The fenestration zones can be transversely opposite to each other. Alternatively, the fenestration zones can be located at a predetermined angle a around the circumference of the graft sleeve. Angle a can be determined from the anatomy of the patient or by other criteria.

Generally, the prosthesis will also comprise at least one stent attached to the first end of the tubular graft sleeve. The first end will usually be the proximal end of the tubular graft sleeve (i.e. located closer to the heart). After deployment, the stent attached to the first end of the graft sleeve will expand against the luminal surface of the body vessel into which the prosthesis is deployed. The stent can be formed from any resilient biocompatible material, as known in the art. The stent can be balloon expandable or self-expandable. Suitable materials include metals (e.g. stainless steel, nitinol) and polymers, particularly engineering high modulus polymers such as polyether ether ketone (PEEK). PEEK polymers with shape memory behaviour can be used. Exemplary stent configurations are known in the art and include wire mesh stents, helices, coils, rings and other suitable configurations; see US 4735645, US 6635080 and US 6203568.

Each stent can be independently formed of any suitable biocompatible material having the necessary resilience to fold inwardly into a first folded configuration (i.e. for packaging] and to adapt a second open configuration (i.e. after deployment].

Optionally, one or more ring stents can be attached to the first end of the graft sleeve. The ring stents can each be formed from nitinol wire and will typically include multiple windings of nitinol wire. Each stent can be attached to the external surface of the sleeve or to the internal (luminal) surface of the sleeve. Generally) it is more convenient to attach the stents to the external (non-luminal) surface of the sleeve.

In one embodiment) the first end of the graft sleeve comprises a pair of ring stents which) after deployment, together hold the graft sleeve in position within the body vessel. Optionally, the two stents can be formed of nitinol wire. The ring stent closest to the first end of the graft sleeve can be of a shallow sinusoidal configuration, with the second ring stent (further along the graft sleeve) being of circular or sinusoidal configuration. Optionally, a stabilising stent member (or a pair of such members) as described in PCT/GB2012/051236 can be located between the two ring stents.

The number of strands of wire in a ring stent can be varied according to the diameter of wire utilised and the size of graft. The number of strands wound can vary from 2 to 120 or even more, but would typically have 10 to 30 strands forming the ring stent. Any diameter wire which maintains the required resilience can be used. Suitable diameters for the wire can be selected from a range of 0.1 mm to 2 mm, for example 0.5 mm to 1 mm.

Each stent can conveniently be positioned externally of the sleeve of the prosthesis.

Conveniently, each stent is attached to the graft sleeve by sewing) but any other suitable means of attachment to the sleeve (e.g. adhesive or heat bonding] could alternatively be used.

A stent which is ring-shaped (annular] will have an inner circumference substantially identical to (preferably identical to] the outer circumference of the graft sleeve (the tubular graft). By substantially identical tori we refer to a circumference which is equal to or up to 5% greater than the outer circumference of the graft sleeve, preferably 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.

A stent which is sinusoidal or "saddle shaped" refers 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. For convenience, the first pair of points can be described as "peaks", with the second pair of points described as "valleys". 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 (saddle shaped) configuration can be located. Thus, the ratio of 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 to be attached. The percentage oversize of the undistorted inner circumference of the circular stent relative to the outer circumference of the graft sleeve also gives a convenient measure of the saddle shape adopted) and can be calculated as: Oversize % = [Stent inner diameterS Graft sleeve outer diameterl x 100% Graft sleeve outer diameter Optionally the first end of the graft sleeve can comprise two stents: a first stent which is a saddle-shaped stent and a second stent which is a ring or saddle-shaped stent. Thus, the terminal stent can be formed of a continuous loop of resilient material (nitinol or PEEK or the like) having a sinusoidal (saddle) shape as described above. This saddle shaped stent can have a saddle height of 4 to 8 mm and is conveniently located at one end of the graft sleeve. A second stent formed in a continuous loop and can be in circular form with an inner circumference substantially identical to the outer circumference of the graft sleeve is also present adjacent the saddle shaped stent. Alternatively the second stent can be a saddle shaped stent. The second stent can also be formed from resilient material (nitinol or PEEK or the like). The resilient material can be formed as an elongate strand and wound into a loop. Conveniently these two stents are spaced S to 13 mm apart (for example 5 to 8 mm at the closest point] and provide good sealing of the graft prosthesis against the luminal wall of the blood vessel.

The stent graft prosthesis can be inserted into the patient using a delivery catheter and, once correctly located at the site requiring treatment, is deployed by the withdrawal of a delivery sheath of the delivery catheter. Balloon-expandable grafts are then caused to expand in diameter by inflation of a balloon located within the lumen of the graft Self-expandable grafts radially expand upon release from the outer tube. Irrespective of the mode of expansion, once deployed, the stents hold the graft in location by contact with the inner walls of the blood vessel.

Since the stent graft prosthesis will need to be compressed for loading into the catheter and during delivery, in general terms, each stent is formed from the minimum amount of material able to maintain the patency of the sleeve lumen at the required diameter.

In one embodiment, the prosthesis remains attached to its catheter after the sheath is retracted. A suitable graft of this type is the ANACONDA® graft of Vascutek Ltd., UK (see US 6,635,080).

In one embodiment, where the graft is to be inserted in a blood vessel, the method of the invention employs a graft which can be at least partially collapsed to allow blood flow between the outer surface of the graft and the inner lumen of the blood vessel until correction location has been achieved. Such perfusion avoids the risk of ischemia and consequent damage to tissue.

In a further aspect, the present invention provides an implantable prosthesis comprising: i) a compliant and substantially fluid impervious tubular sleeve having a longitudinal axis and a proximal end and a distal end with a conduit therethrough; ii) a first ring stent formed from multiple windings of wire of a shape memory material, attached to said sleeve at said proximal end; Hi) a fenestration through said sleeve located in a planar portion of a fenestration zone, wherein said zone is formed from sufficient material to enable movement of said fenestration.

In a further aspect, the present invention provides a method of treating a target site proximate to a branch vessel intersection) said method comprising inserting a prosthesis comprising a tubular graft sleeve of a biocompatible material having an aperture in a side wall of the tubular graft sleeve, wherein said graft sleeve is provided with a moveable fenestration zone associated with the aperture, said fenestration zone comprising I) a first portion which is planar, and is fenestrated; H) a flexible second portion connecting the first portion with the graft sleeve, and iii) a resilient member connected to the first portion; wherein the first portion is of greater size than the aperture, the second portion is connected around the aperture, and the resilient member acts to maintain planarity of the first portion into a branched vessel so that a fenestration is aligned with said branch vessel. The prosthesis may be deployed in this position. A fluid, typically blood, is able thereby to flow to the branch vessel from the lumen of the tubular graft sleeve via the aligned fenestration. In one embodiment, the prosthesis will be inserted so that the fenestration is aligned with the branch vessel. The fenestration may be then cannulated, and can optionally be stented. A deployment device allowing adjustment of the graft position can advantageously be used to adjust the position of the prosthesis whilst the fenestration position is unchanged. A change of prosthesis position within the main blood vessel relative to the fenestration can be accommodated by the second portion which allows the fenestration zone to slide relative to the prosthesis.

In the aspect described above for treatment of a target site, the target site can include an aneurysm which is treated through deployment of the prosthesis.

Optionally the aneurysm is a thoracic aortic aneurysm.

In the aspect described above for treatment of a target site, the prosthesis according to the present invention can be inserted so that the fenestration is proximal (with respect to the heart] to the branch vessel intersection. Where two branch vessel intersections are present but are not located 180' to each other (due to the patient's natural anatomy), the prosthesis can accommodate the alignment of the fenestrations as required through the degree of movement of the fenestration zone, allowed by the inclusion of the second portion.

Additionally, the prosthesis is desirably inserted using endovascuhr techniques.

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 context demands otherwise.

The present invention will now be further described by reference to the following figures in which: Fig. 1 shows a side view of an embodiment of the present invention in the form of a bifurcated stent-graft; Fig. 2 shows a perspective view of a variant in construction of an embodiment similar to that illustrated in Fig. 1, and a'so where the fenestration zone is inverted; Fig. 3 shows a close-up view of the stent-graft shown in Fig. 1, with the fenestration zone everted to provide detail on construction; Fig. 4 shows a side view detail of an alternative embodiment having two fenestration zones, each everted for clarity; and Fig. S shows a schematic plan view of a fenestration zone.

One embodiment of the present invention is illustrated in Fig. 1 and is shown in the form of a bifurcated vascular stent-graft (1) having a main body (10) which bifurcates into two separate legs (8, 8'). The graft is formed with a main tubular body (10) in which the fenestration zone is located. The main body (10) of the graft (1) then divides into two smaller legs, (8, 8'). However, it is not necessary for the graft (1) of the present invention to be bifurcated; alternative embodiments may maintain a constant diameter or may be tapered.

The fenestration zone includes a fenestration (2) which is bounded by a support member (3) formed from a strand of resilient material such as nitinol wire.

Conveniently the support member (3) is sewn around the periphery of the fenestration (2) and stitches are illustrated on the figure. Other forms of attachment, e.g. gluing, heat bonding or welding, are also possible. A single strand or multiple strands of the resilient material may be present, depending upon the diameter of wire used. For clarity of illustration only a single wire is shown in the figures. Around the periphery of the fenestration (2) is a planar portion (4). In this embodiment, the planar portion (4) is circular, but alternative shapes are also possible. The planar portion [4) is joined to a second portion (not shown in Fig. 1) which links the external boundary of planar portion (4) to the graft body (10). In the embodiment illustrated, the second portion is sewn onto the boundary of planar portion (4) on one side and on its opposite side is sewn on to the side wall of the main body (10). As illustrated in Fig. 2 the boundary between planar portion (4) and the second portion is reinforced by a resilient member (6) which can be one or more strands of a resilient material, such as nitinol wire, and is conveniently sewn in place.

In the embodiment illustrated in Fig. 1 the graft (1) may be formed from a flexible material such as polyester or polypropylene, suitable for a biocompatible graft Other biocompatible graft materials could also be used. The graft shown in Fig. 1 also includes ring stents (7, 7'), but these are not essential to the invention and alternative formations or stent types are possible. Leg 8' is illustrated with stents attached; the arrangement, type of member of stents present can be modified or omitted, as required. The non-stented leg (8) could also be stented, if desired.

Fig. 2 shows an inverted fenestration zone in an embodiment in which the second portion (9) is visible and formed integrally with main body (10) and eversible about fold line or junction (5). Alternatively, the junction (5) between the second portion (9) and the main body (10) may be achieved by sewing or other methods, for example gluing or heat welding. Optimally, in other embodiments the junction (5) between second portion (9) and main body (10) could be supported by a resilient member.

Fenestration (2) is located on a first planar portion (4), with a support material (3) defining the boundary of the fenestration (2). The first planar portion (4) includes a resilient member (6) around its outer periphery. Resilient member (6) may be formed from one or more strands of a resilient material, such as nitinol wire, with the number of strands selected being dependent upon the diameter of the material used. Resilient member (6) is located approximately at the junction between planar portion (4) and the second portion (9) spanning between the boundary of the planar portion (4) and the graft sleeve (10).

Fig. 3 shows the fenestration zone of the graft of Fig. 1 everted outwardly to show clarity of its construction. Only a portion of the graft (1) is illustrated. The fenestration (2) is surrounded by a support member (3), typically nitinol wire which is sewn around the outer circumference of the fenestration (2). Planar portion (4), illustrated as circular (although other shapes are possible) surrounds the fenestration (2). The planar portion (4) is bounded at its outer periphery by a resilient member (6), typically one or more strands of nitinol wire. As is clearly illustrated in Fig. 3, the planar portion (4) is held in a planar configuration through tension between support member (3) and resilient member (6). A second portion (9) (formed of biocompatible graft material) (not shown in Fig. 3) links between the outer edge of planar portion (4) at resilient member (6) and the side wall (10) of graft (1).

Fig. 4 shows a side view of a portion of an akernative embodiment of a stent-graft (1) of the present invention. In this embodiment, main body (10) has two) diametrically opposed fenestration zones. Each fenestration zone comprises a generally circukr aperture or fenestration (2) which is bounded around its periphery by a support member (3), such as nitinol wire sewn at its edge. A planar portion (4) extends from the support member (3) through to its outer circumference, also bounded by a resilient member (6) sewn therearound. A second portion (9) extends from the outer edge of the planar portion (4) and is joined to main body (10) of graft (1). As is easily seen in Fig. 4, the second portion (9) is simply attached to main body (10) by stitching to form junction (5). However, it is also possihle that the second portion (9) could be formed integrally with main body (10) (as illustrated in Fig. 2). Optionally a further resilient member could be located at the junction (5) between second portion (9) and the main body (10).

In the embodiment shown in Fig. 4, the two fenestration zones are shown diametrically opposite each other. However, the arrangement of the fenestration zones could be altered) as required) for example to accommodate a patienfs anatomy. Where two or more fenestration zones are located on a graft) it is not essential for these to be axially aligned (relative to the main longitudinal axis of the graft) nor to be diametrically opposed. One skilled in the art would be able to adjust the location of the fenestration zones in any particular graft, as required.

Fig. 5 shows a phn view of a phnar portion (4) illustrating both the aperture (2) with support member (3) located therearound. In this embodiment, the outer boundary edge (11) of the phnar portion (4) is substantially circular. This outer edge is supported by a substantially ring shaped resilient member (6) which is illustrated with four circumferentially spaced spring sections. Each spring section consists of an inward bend (20), outward bend (22) and a further inward bend (21).

The presence of the spring sections facilitates the tensioning of the fabric of planar portion [4] and biases the resilient member to adopt the illustrated configuration if subjected to a temporary deformation due to external forces e.g. experienced during delivery of the prosthesis.

Claims (12)

1. Claims 1. A prosthesis comprising a tubular graft sleeve of a biocompatible material having an aperture in a side wall of the tubular graft sleeve, wherein said graft sleeve is provided with a moveable fenestration zone associated with the aperture, said fenestration zone comprising i] a first portion which is planar, and is fenestrated; ii] a flexible second portion connecting the first portion with the graft sleeve, and iii] a resilient member connected to the first portion; wherein the first portion is of greater size than the aperture, the second portion is connected around the aperture, and the resilient member acts to maintain planarity of the first portion.
2. 2. A prosthesis as claimed in claim 1, wherein the fenestration zone includes at least one fenestration.
3. 3. A prosthesis as claimed in claim 1 or claim 2, wherein the second portion links the graft sleeve to the planar portion.
4. 4. A prosthesis as claimed in any one of claims 1 to 3, wherein the second portion spans between the boundary of the fenestration zone in the wall of the graft sleeve and the outer perimeter of the first planar portion.
5. S. A prosthesis as claimed in any one of claims 1 to 4, wherein the at least one fenestration, or each fenestration is bounded by a strand of resilient material.
6. 6. A prosthesis as claimed in claim 5, wherein the resilient material is selected from the group consisting of physiologically benign metals and plastics, for example nitinol wire or a strand of po]yether ether ketone (PEEK].
7. 7. A prosthesis as claimed in any one of the preceding claims, wherein the fenestration zone comprises an invertible collar associated with the perimeter of the planar portion, which material has at least a first configuration in which the material protrudes outwardly with respect to the lumen of the graft and a second configuration in which the material inverts into the lumen of the graft
8. 8. A prosthesis as claimed in claim 7, wherein the invertible collar has a further neutral configuration in which the collar is neither protruding nor inverted S and is generally aligned with the plane of the planar portion.
9. 9. A prosthesis as claimed in any one of the preceding claims, wherein the graft sleeve forms the side walls of a main body portion of the graft 10. A prosthesis as claimed in any one of the preceding claims, wherein the graft is a bifurcated graft) and the graft sleeve forms at least part of a wall of a first leg and/or a second leg after bifurcation.11. A prosthesis as claimed in any one of the preceding claims, wherein the planar portion includes a support member associated with the outer edge of the planar portion, wherein the support member has selected biased weak points configured to accommodate or absorb movement of the fenestration zone.12. A prosthesis as claimed in claim 11, wherein the support member is located at the perimeter of the planar zone and remote from the fenestration.13. A prosthesis as claimed in claim 11 or claim 12, wherein at least one selected biased weak point comprises a resilient element) such as a spring section.14. A prosthesis as claimed in any one of the preceding claims wherein the fenestration is located centrally in a first planar portion.15. A prosthesis as claimed in any one of the preceding claims wherein the second portion includes a support member, such as a strand of resilient material) for example nitinol wire or a strand of PEEK.16. An implantable prosthesis comprising: i) a compliant and substantially fluid impervious tubular sleeve having a longitudinal axis and a proximal end and a distal end with a conduit therethrough; H) a first ring stent formed from multiple windings of wire of a shape memory material, attached to said sleeve at said proximal end; iii) a fenestration through said sleeve located in a planar portion of a fenestration zone, wherein said zone is formed from sufficient material to enable movement of said fenestration.17. A prosthesis comprising a graft sleeve having a first end and a second end, with a lumen extending therethrough from the first end to the second end, wherein said graft sleeve comprises an fenestration zone having a planar portion which is fenestrated and a second portion located between said graft sleeve and said pknar portion, wherein the fenestration zone has alternative inverted and everted configurations with respect to the graft sleeve, in which respective configurations the second portion extends into the lumen, and outwardly from the graft sleeve.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS: Claims 1. A prosthesis comprising a tubular graft sleeve of a biocompatible material having an aperture in a side wall of the tubular graft sleeve, wherein said graft sleeve is provided with a moveable fenestration zone associated with the aperture, said fenestration zone comprising i) a first portion which is planar, and is fenestrated; ii) a flexible second portion connecting the first portion with the graft sleeve, and iii) a resilient support member connected to the first portion; wherein the first portion is of greater size than the aperture, the second portion is connected around the aperture, and the resilient support member acts to maintain planarity of the first portion.2. A prosthesis as claimed in claim 1, wherein the resilient support member is located at the periphery of the first portion.3. A prosthesis as claimed in claim 1, wherein the second portion spans between the boundary of the aperture in the side wall of the tubular graft o sleeve and the outer perimeter of the first portion.(4 4. A prosthesis as claimed in claim 1, wherein the fenestration zone includes at least one fenestration located centrally within the first portion, so that an area of the first portion extends all around the fenestration.5. A prosthesis as claimed in claim 4, wherein the at least one fenestration is bounded by a strand of resilient material.6. A prosthesis as claimed in claim 5, wherein the resilient material is selected from the group consisting of physiologically benign metals and plastics, for example nitinol wire or a strand of polyether ether ketone (PEEK).7. A prosthesis as claimed in any one of the preceding claims, wherein the graft sleeve forms the side walls of a main body portion of the graft 8. A prosthesis as claimed in any one of the preceding claims, wherein the graft isa bifurcated graft, and the graft sleeve forms at east part of a wall of a first eg and/or a second leg after bifurcation.9. A prosthesis as claimed in any one of the preceding claims, wherein the resilient support member connected to the first portion has biased weak points configured to accommodate or absorb movement of the fenestration zone.
10. 10. A prosthesis as claimed in claim 9, wherein the resilient support member is ocated at the perimeter of the first portion and remote from the fenestration.
11. 11. A prosthesis as claimed in daim 9 or claim 10, wherein at least one biased weak point comprises a resilient element) such as a spring section.
12. 12. A prosthesis as claimed in any one of the preceding claims wherein the second portion includes a support member. LtD13. A prosthesis as claimed in claim 12, wherein the support member is a strand of resilient material, for example nitinol wire or a strand of PEEK.14. A prosthesis as claimed in claim 13, wherein the strand of resilient material is sewn around the circumference of the second portion, at or adjacent its junction with the first portion.15. A prosthesis as claimed in claim 12, wherein the support member is a tubular mesh or zig-zag stent.