GB2476649A

GB2476649A - Stent or graft device with a self-inflating collar

Info

Publication number: GB2476649A
Application number: GB0922598A
Authority: GB
Inventors: Clifford Murch
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-12-29
Filing date: 2009-12-29
Publication date: 2011-07-06
Also published as: GB0922598D0

Abstract

Disclosed is a stent or graft device 26 comprising a support structure forming a passageway. Located on the support structure is a self-inflating collar 28, which is capable of inflating when blood flows through the passageway formed by the support structure. The device 26 is preferably used to treat aneurysms 23, with the self-inflating collar 28 providing a seal in said aneurysm 23. The self-inflating collar 28 may be located at one end of the stent or graft 26. A plurality of self-inlating collars 28 may be provided at the distal and proximal ends 26a of the device 26 and at bifurcated distal ends. The self-inflating collar 28 can extend from a folded, concertina-like state to a fully inflated form. During deployment, the outer profile of the collar is substantially flat and, one deployed, fills with blood to form an inflated collar 28. Holes 29 may be provided within the collar, which allow blood to enter and inflate it.

Description

SELF-SEALING COLLAR FOR A MEDICAL DEVICE

FIELD OF THE INVENTION

The present invention relates to an intraluminal or endovascular medical device with a self-sealing collar. More particularly, the present invention relates to an intraluminal or endovascular stent or graft device with a self-sealing collar.

BACKGROUND OF THE INVENTION

An aneurysm is the dilatation of a blood vessel, associated with weakening of the wall of the vessel, resulting in its rupture and an associated, often catastrophic, haemorrhage.

Aneurysm of large blood vessels most commonly affects the abdominal aorta, usually the part below the origins of the renal arteries that supply the kidneys, the infra-renal aorta and extending to and sometimes including the bifurcation of the aorta into the common iliac arteries.

lnfra-renal aortic aneurysm most commonly affects men over the age of 65 years and is usually asymptomatic until or immediately before the aneurysm ruptures when the patient will experience severe pain.

The only treatment has, until recently, been surgery to replace the aneurysm sac, the dilated portion of the vessel, with a graft of artificial, usually woven material, such as Dacron (Trade Mark). This requires a major intra-abdominal surgical procedure in patients who are usually elderly and may have other co-morbidity making this procedure hazardous and the recovery period is often protracted. Patients frequently spend several days in intensive care, sometimes needing ventilation to assist breathing and dialysis for renal failure.

Despite this, survival rates for this procedure when performed before rupture are good, in the order of 90% but in the emergency situation of a ruptured aneurysm, survival may be as low 10%.

With the development of increasingly sophisticated interventional procedures and devices, it is now possible to repair these arteries using devices introduced through small incisions in the groin to allow access of these devices into the arterial system. This is called Endovascular Aneurysm Repair (EVAR).

This procedure requires much less intensive post-operative care and the patients are often able to go home a day or two after the procedure.

The devices consist of a tubular graft at the top end, which is held in place by a variable system of barbed stents, which grip the lining of the aorta above or below the renal arteries, depending upon the manufacturer's design. At the lower end, the grafts nowadays usually bifurcate, with one limb of the graft extending into each of the iliac arteries, the level of which depend upon the extent of the aneurysm and the size of the native vessels.

The stent/graft acts as a conduit to carry the blood through the aneurysm, excluding" the aneurysm sac from the arterial circulation and therefore depressurising it and thereby, preventing its rupture. The aneurysm sac remains intact, unlike the surgical repair. Success of the procedure relies on a tight seal between the stent/graft and the arterial wall, to prevent the aneurysm sac receiving arterial pressure and therefore retaining the risk of rupture.

Endoleaks, as they are called when pressurised blood persistently reaches the aneurysm sac despite the stent/graft, can occur in a number of ways, many are self limiting and do not require further treatment. However, leakage around the seal between the proximal (top) end of the graft, into the aneurysm sac, and occasionally leakage at the distal (lower) end between the distal end of the graft and the iliac arteries, a type I endoleak, is a serious problem, often difficult to resolve and associated with persistent pressurisation of the aneurysm sac and subsequent rupture. Whilst the endoleak may arise at the time of the EVAR procedure, the aorta may continue to dilate with time and the endoleak develop later.

Not all aneurysms are suitable for EVAR. The most important criterion for all devices is the configuration of the neck of the aneurysm, the part of the aorta just below the renal arteries, where the device will seal into the aorta. Whilst the diameter of the devices has increased to accommodate large diameter aneurysm necks, the required length of the neck has remain fairly constant at about 15 mm and the walls of the neck need to be parallel. With a diverging, conical neck it is much less likely to be possible to achieve a seal and more likely to result in a type I endoleak. Angulation of the neck, from the line of the aorta of greater than degrees is also associated with increased risk of an endoleak.

Therefore, although there are many prior art devices and methods on the market all of these have associated disadvantages.

It is an object of at least one aspect of the present invention to obviate or mitigate at least one or more of the aforementioned problems.

It is a further object of at least one aspect of the present invention to provide an improved stent or graft device comprising a self-sealing collar.

It is a further object of at least one aspect of the present invention to provide an improved method of treating ruptured aneurysms.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a stent or graft device comprising: a support structure capable of forming a passageway; a self-inflating collar located on the support structure; wherein the self-inflating collar is capable of inflating when blood flows through the passageway formed by the support structure.

The present invention therefore relates to a stent or graft comprising a self-inflating collar (e.g. cuff) which may be capable of providing an improved seal in an aortic aneurysm. The stent or graft device may therefore be used in Endovascular Aneurysm Repair (EVAR) methods and apparatus.

There are four main objectives of this invention. First, the invention may facilitate a successful seal at the time of placement of the EVAR device.

Secondly, the invention may expand, if required to maintain the seal, in the event that the aorta continues to dilate over time. Third, the invention may allow aneurysms currently deemed unsuitable for treatment by EVAR, because of the configuration of the neck of the aneurysm, to be treated successfully and fourth, improve and increase the use of EVAR in the treatment of ruptured aneurysms.

The support structure may comprise a substantially tubular structure.

Typically, there may be one self-inflating collar which may be located at one end (e.g. the proximal end) of the stent or graft. By self-inflating is meant that the collar inflates without any intervention by an operator (e.g. radiologist) and inflates under blood pressure once the stent or graft is attached to an aortic aneurysm and connected to the blood flow of a patient.

Alternatively, there may be two or more or a plurality of self-inflating collars.

In particular embodiments, there may be one self-inflating collar located at the proximal end and at least one self-inflating collar located at the distal end. In some embodiments the distal end may, for example, be bifurcated and around each bifurcation there may be a self-inflating collar.

The self-inflating collar may therefore have a deflated (e.g. compressed) form and an inflated (e.g. expanded) form. The inflated form may have a diameter greater than a main tubular structure forming the main central part of the support structure. The self-inflating collar may extend from a folded state via a concertina-like arrangement into a fully inflated form. Moreover, in the event that an aorta continues to dilate over time, then the collar may further expand to maintain a good seal over the rest of the lifetime of the patient.

The self-inflating collar may be integrally formed with the rest of the support structure or alternatively may be made separately and then attached using any appropriate means (e.g. stitching, welding or gluing).

The self-inflating collar may be a substantially flexible structure which may adapt and/or conform to areas (e.g. neck areas) in an aortic aneurysm that are not substantially tubular in shape and may in fact be deformed into, for example, a divergent or substantially divergent shape. The self-inflating collar may therefore have the ability to expand more or less than other parts of the collar meaning that the collar may adapt and/or conform to exactly the area to be sealed in and/or adjacent to the aortic aneurysm. This may be achieved by manufacturing the self-inflating collar from flexible material so that a good seal is obtained whatever the size and conformation of the area to be blocked. The profile of the self-inflating collar may therefore conform to the configuration and/or size of the neck of an aneurysm, thereby achieving a seal and depressu rising the aneurysm sac by excluding the aneurysm from arterial pressure.

During deployment, the outer profile of the collar may be substantially flat to facilitate deployment by an operator (e.g. radiologist). Once in place, the self-sealing collar may fill with blood at arterial pressure and self-inflate to form an inflated collar capable of conforming to the contours and/or size of the neck of an aneurysm.

The self-inflating collar may be constructed in any appropriate manner as long as the collar is capable of expanding under standard blood pressure. For example, the self-inflating collar may comprise a folded ring of material which may be attached to the support structure. The self-inflating collar may be sealed to the support structure on the side of the aneurysm. Blood at arterial pressure therefore cannot enter the aneurysm. The material forming the self-inflating collar may be sealed and/or attached in the upper and lower regions around the stent or graft device. This may allow a central unattached region to expand and/or inflate under blood pressure. This central unattached region may expand in an annular manner around the stent or graft device to form a seal in an aortic aneurysm.

The stent or graft device may also comprise fixing mechanisms (e.g. anchors, barbs etc.) to securely attach the device in place. In particular embodiments, the self-inflating collar may be located just below the proximal, aortic fixing mechanism, within the neck of the aneurysm, at the top end and just above the distal fixing mechanism in the iliac arteries, at the lower end.

In order for the collar to self-inflate, blood under arterial pressure needs to enter the collar. This can be achieved in, for example, two ways: 1. The upper and lower regions of the collar (which encircle the support structure) may be sealed and/or attached to the tubular graft component of the stent or graft device, so that the collar forms a sealed, expandable ring around the stent or graft device. The stent or graft device may then be perforated by several small holes which lie between upper and lower seals of the collar, allowing blood at arterial pressure to enter and inflate the collar, effecting the seal.

2. The ends of the collar away from the aneurysm, upper end at the aorta and lower end at the iliac arteries, may be attached to the stent or graft device material by a series of threads, like a parachute. The stent or graft is not perforated and blood only enters the collar if a leak occurs around the fixing mechanism, resulting in a seal.

The distance between the upper and lower sealed and/or attached areas of the collar to the stent or graft at the aortic end may be between 10 and 15 mm.

The collar when expanded may therefore fill the neck of an aneurysm. A smaller cuff may be required at the iliac end of the stent or graft device.

In the deflated (e.g. compressed) form the collar may be folded flat or substantially flat against, for example, the main tubular component of the stent or graft device. The collar may be adjacent to a fixing mechanism. The circumferential size of the folded cuff may be less than the fixing mechanism and therefore does not increase the overall size of the un-deployed device, for

introduction into the arterial system.

The collar may vary in size and configuration, depending upon the configuration of the aneurysm neck and the iliac arteries although a single shape and size makes this more practical in clinical use. It is intended that the stent or graft device according to the present invention may be used to attach to any of the currently available EVAR stent/graft devices.

The self-sealing collar will usually be made from any appropriate implantable material. In particular embodiments the self-sealing collar may be made from the same material as the EVAR device graft material, as it will need to contain blood at arterial pressure. The materials used may vary depending upon the manufacturer's choice for their device. For example, expanded polytetrafluoroethylene (ePTFE) or woven Dacron (Trade Mark) may be used.

According to a second aspect of the present invention there is provided a method of sealing and/or repairing an aortic aneurysm, said method comprising: providing a support structure capable of forming a passageway; providing a self-inflating collar located on the support structure; wherein the self-inflating collar is capable of inflating when blood flows through the passageway formed by the support structure.

The method may use a stent or graft device as defined in the first aspect.

According to a third aspect of the present invention there is provided a method of treating an aortic aneurysm using a stent or graft device as defined in the first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic view from the front of an aortic aneurysm, with a neck suitable for endovascular repair with prior art devices such as an EVAR stent/graft device; Figure 2 is a schematic view of the aortic aneurysm shown in Figure 1 with an EVAR stent/graft device according to the prior art fitted in place; Figure 3 is a schematic view from the front of an aortic aneurysm, with a neck not well suited for endovascular repair with a prior art device such as an EVAR stent/graft device; Figure 4 is a schematic view from the front of an aortic aneurysm, with a neck not well suited for endovascular repair but with a prior art device such an EVAR stent/graft device in place; Figure 5a is a schematic view of the proximal end of a stent or graft device with a self sealing cuff attached shown in an inflated form according to an embodiment of the present invention; Figure 5b is a schematic view of the proximal end of the stent or graft device shown in Figure 5a in an un-inflated form; Figure 6a is a schematic longitudinal view of the proximal end of the stent or graft device shown in Figure 5a in an inflated form; Figure 6b is a schematic longitudinal view of the proximal end of the stent or graft device shown in Figure Sb in an un-inflated form; Figure 7 is a schematic cross-sectional view of the proximal end of the stent or graft device shown in Figure Sb in an un-inflated form; Figure 8 is a schematic longitudinal sectional view through the proximal end of an aneurysm with a neck not well suited to endovascular repair, with a stent or graft device in place according to an embodiment of the present invention; and Figure 9 is a schematic view from the front of an aortic aneurysm, with a neck not well suited for endovascular repair with an EVAR stent/graft device, with a stent or graft device in place according to a further embodiment of the present invention wherein the stent or graft device has a self sealing collar at both proximal and distal ends.

BRIEF DESCRIPTION

Generally speaking, the present invention resides in the provision of a stent or graft device which has a self-sealing member which provides an improved seal in an aortic aneurysm.

Figure 1 is a representation of the anatomy of an aortic aneurysm. Figure 1 shows that the aortic aneurysm comprises a supra-renal aorta 20 which lies above the renal arteries 21. The renal arteries 21 supply the kidneys, and are where some EVAR stent/graft devices attach to the aorta. Figure 1 also shows that below the renal arteries 21 there is a substantially tubular region in the form of a neck 22. As the neck 22 is substantially tubular in shape (and not deformed) the neck 22 is suitable for endovascular repair because it is at least 15mm long and has parallel sides before opening into the aneurysm sac 23. Slight aneurismal dilatation is also shown in the common iliac arteries 24.

Figure 2 shows the attachment of a prior art of an EVAR stent/graft device 26. The EVAR stent/graft device 26 provides good sealing to the neck 22 and iliac limbs of the EVAR stent/graft device 31 seal into the iliac arteries 24. This prevents pressurised blood reaching the aneurysm sac 23, which is excluded from the circulation and prevents future rupture of the aneurysm.

Figure 3 is a representation of an abdominal aortic aneurysm which similar to the aortic aneurysm in Figure 1 comprises a supra-renal aorta 20 which lies above the renal arteries 21. There is also an aneurysm sac 23. The difference in this aortic aneurysm is that the neck 25 is not substantially tubular in shape and is in fact deformed into a divergent shape. It is therefore not possible to achieve a seal around the neck 25 using a standard EVAR stent/graft device.

Figure 4 is a representation of the aortic aneurysm shown in Figure 3 with a prior art EVAR stent/graft device 26 in place. It is clear that gaps generally designated 18 occur between the divergent neck 25 and the stent/graft device 26 which will allow blood to continue to enter the aneurysm sac 23. The stent/graft device 26 has a tubular proximal end which does not provide a good fit with the divergent neck 25. Figure 4 also shows that the stent/graft device 26 has bifurcated distal ends 31 located between a spacer region 24. As the tubular proximal end does not provide a good seal at the divergent neck 25, pressurised blood leaks into the aneurysm sac 23, which remains at arterial blood pressure.

This is known as a type I endoleak and requires to be fixed as the risk of the aneurysm rupturing remains.

Figure 5a is a schematic view of the proximal end of the stent or graft device 26 according to the present invention shown in an inflated form. Figure 5a shows that towards the end of the proximal end of the stent or graft device 26 there is an inflated collar 28. The inflated collar 28 is ring-like and functions as a self-sealing collar. By self-sealing is meant that the collar inflates after being fixed due to being filled with blood and is then kept inflated due to blood pressure. Figure 5a also shows that the inflated collar 28 is located just below the proximal end 26a of the stent or graft device 26. The proximal end 26a may comprise a fixing mechanism (not shown) to allow the stent or graft device 26 to be attached to the neck 25 of an aortic aneurysm. The profile of the inflated collar 28 is adapted to conform to the configuration of the neck 25 of the aneurysm and achieve a seal, depressurising the aneurysm sac 23 by excluding the aneurysm from arterial pressure.

Figure 5b shows the deflated collar 27 as it would be at deployment of the stent or graft device 26. The outer profile 27a of the deflated collar 27 is substantially flat to facilitate deployment by an operator (e.g. radiologist). Once in place, the self-sealing collar fills with blood at arterial pressure and inflates to form the inflated collar 28 and conforms to the contours of the neck 25.

Figure 6a is a schematic longitudinal view of the proximal end of the stent or graft device 26 in an inflated form. Figure 6a shows that the collar, generally designated 50, is attached using stitching 30 to the stent or graft device 26 sO that this joint is water tight. As Figure 6a shows there is stitching 30 above and below the collar which is in an inflated form 28 which forms a water-tight seal.

Figure 6a also shows that the self-sealing collar 50 comprises a hole 29 through which blood may flow and inflate the collar 50. Figure 6b is a view of the stent or graft device 26 in an un-inflated form.

As shown in Figures 6a and 6b there is a collar 50 has an expanded form 28 and a compressed form 27. In Figure 6a where the stent or graft device 26 is in an inflated form 28 the collar 50 extends fully out in concertina-like arrangement. The collar 50 comprises upper concentric regions 52,54 and lower concentric regions 56,58 which are flexible and allow the collar 50 to expand and compress and thereby form a successful seal against a neck of an aortic aneurysm. Once in place and the blood flow has been restored by the operator then the collar 50 will inflate and expand almost immediately. Moreover, in the event that aorta continues to dilate over time, then the collar 50 may further expand to maintain a good seal over the rest of the lifetime of the patient.

Figure 7 is a cross-sectional view of the proximal end of the stent or graft device 26 in an un-inflated form. Figure 7 shows that there are six holes 29 which may be used to allow blood to flow into the collar 50 and fill and expand the collar 50. However, it should be noted that any number of holes 29 may be used to inflate the collar 50.

Figure 8 is a view of the stent or graft device 26 according to the present invention in use. The collar 50 is shown in its inflated form 28. This ensures a seal is formed in an aneurysm divergent neck 25 that is not ideally suited for endovascular repair with prior art devices. The stent or graft device 26 according to the present invention therefore allows the aneurysm sac 23 to be excluded and preventing a type I endoleak. Figure 8 also shows that as the collar 50 is flexible in nature one side of the collar 50 may expand more than the other providing a good seal.

Figure 9 is a view of a further embodiment of the present invention. There is shown an aortic aneurysm comprising a supra-renal aorta 120 which lies above the renal arteries 121. There is also an aneurysm sac 123. Figure 9 shows that below the renal arteries 121 there is a neck 125 which is divergent.

At the distal end of the stent or graft device 126 there are two bifurcated members 131a,131b. Around each of the bifurcated members 131a,131b there isa collar 132a,132b as previously described at the proximal region. The stent or graft device 126 therefore has an inflatable collar 128 at the proximal region and inflatable collars 132a,132b at the distal region. The stent or graft device 126 therefore provides sealing at both proximal and distal ends. The inflatable collar functions as previously described.

Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention. For example, any suitable type of inflatable collar may be used to provide a good seal. Moreover, the collars may be self-sealing and may be located at any suitable location on the stent or graft device.

Claims

CLAIMS1. A stent or graft device comprising; a support structure capable of forming a passageway; a self-inflating collar located on the support structure; wherein the self-inflating collar is capable of inflating when blood flows through the passageway formed by the support structure.
2. A stent or graft device according to claim 1, wherein the self-inflating collar is capable of providing a seal in an aortic aneurysm.
3. A stent or graft device according to any of claims 1 or 2, wherein the support structure comprises a substantially tubular structure.
4. A stent or graft device according to any preceding claim, wherein there is one self-inflating collar located at one end (e.g. the proximal end) of the stent or graft.
5. A stent or graft device according to any preceding claim, wherein there are two or more or a plurality of self-inflating collars.
6. A stent or graft device according to any preceding claim, wherein there is one self-inflating collar located at the proximal end and at least one self-inflating collar located at the distal end.
7. A stent or graft device according to any preceding claim, wherein there is one self-inflating collar located at the proximal end and the distal end which is bifurcated comprises a self-inflating collar located around each of the bifurcated distal ends.
8. A stent or graft device according to any preceding claim, wherein the self-inflating collar has a deflated (e.g. compressed) form and an inflated (e.g. expanded) form.
9. A stent or graft device according to any preceding claim, wherein the self-inflating collar has a diameter greater than a main tubular structure forming a main central part of the support structure.
10. A stent or graft device according to any preceding claim, wherein the self-inflating collar extends from a folded state via a concertina-like arrangement into a fully inflated form.
11. A stent or graft device according to any preceding claim, wherein in the event that aorta continues to dilate over time, then the collar is capable of further expanding to maintain a good seal over the rest of the lifetime of the patient.
12. A stent or graft device according to any preceding claim, wherein the self-inflating collar is integrally formed with the rest of the support structure or is made separately and then attached using any appropriate means (e.g. stitching, welding or gluing).
13. A stent or graft device according to any preceding claim, wherein the self-inflating collar is of a substantially flexible structure which is capable of adapting and/or conforming to areas (e.g. neck areas) in an aortic aneurysm that are not substantially tubular in shape or are deformed into a divergent or substantially divergent shape.
14. A stent or graft device according to any preceding claim, wherein during deployment the outer profile of the collar is substantially flat to facilitate deployment by an operator (e.g. radiologist) but once in place, the self sealing collar fills with blood at arterial pressure and inflates to form an inflated collar capable of conforming to the contours and/or size of the neck of an aneurysm.
15. A stent or graft device according to any preceding claim, wherein the self-inflating collar comprises a folded ring of material which is capable of being attached to the support structure.
16. A stent or graft device according to any preceding claim, wherein material forming the self-inflating collar is capable of being sealed and/or attached in upper and lower regions around the stent or graft device thereby allowing a central unattached region to expand and inflate under blood pressure.
17. A stent or graft device according to any preceding claim, wherein the stent or graft device also comprises fixing mechanisms (e.g. anchors) to securely attach the device in place.
18. A stent or graft device according to any preceding claim, wherein the collar forms a sealed, expandable ring around the stent or graft device wherein small holes which lie between upper and lower circumferential seals of the collar, allow blood at arterial pressure to enter and then inflate the collar, effecting the seal.
19. A stent or graft device according to any preceding claim, wherein ends of the collar away from the aneurysm, and an upper end at the aorta and lower end at the iliac arteries, are attached to the stent or graft device material by a series of threads (e.g. like a parachute) wherein blood only enters the collar if a leak occurs around a fixing mechanism, resulting in a seal.
20. A stent or graft device according to any preceding claim, wherein the distance between upper and lower attachments of the collar to the stent or graft device at the aortic end is between 10 and 15 mm.
21. A stent or graft device according to any preceding claim, wherein in the deflated (e.g. compressed) form the collar is capable of being folded flat or substantially flat against, for example, a main tubular component of the stent or graft device.
22. A stent or graft device according to any preceding claim, wherein the self-sealing collar and support structure are made from any one of or combination of expanded polytetrafluoroethylene (ePTFE) or woven Dacron (Trade Mark).
23. A method of sealing and/or repairing an aortic aneurysm, said method comprising: providing a support structure capable of forming a passageway; providing a self-inflating collar located on the support structure; wherein the self-inflating collar is capable of inflating when blood flows through the passageway formed by the support structure.
24. A method of sealing and/or repairing an aortic aneurysm according to claim 23, wherein a stent or graft device as defined in any of claims 1 to 22 is used.
25. A method of treating an aortic aneurysm using a stent or graft device as defined in any of claims 1 to 22.
26. A stent or graft device as hereinbefore described and/or as shown in Figures 1 to 9.