Devices for forming a fistula between two vessels

Abstract

The present disclosure relates to a stent device for forming a fistula between two vessels of a subjects vascular system, said stent comprising a stent body including: a fluid passageway between a first end opening and a second end opening; at least one fistula opening configured to allow blood flow between two vessels of a subjects vascular system; and an occlusion device configured to selectively close at least one of the first end opening or the second end opening.

Description

DEVICES FOR FORMING A FISTULA BETWEEN TWO VESSELS

[0001] The present disclosure relates to devices, systems and methods for forming a fistula between two vessels of the vascular system of a patient. More particularly, the present disclosure also relates to a stent device with an integrated occlusion mechanism, and to systems and methods using said device.BACKGROUND

[0002] Peripheral arterial disease (PAD) can result from the occlusion of arteries in the limbs and extremities such as the hands and feet. Typically, such occlusion is brought about by atherosclerosis, whereby calcified plaque deposited on the walls of an arterial vessel causes narrowing and blockage of the vessel lumen. Severe cases of arterial blockage in the lower extremities can lead to critical limb ischemia (CLI), a chronic condition characterised by severe pain and slow healing of wounds in the affected extremities due to poor circulation of blood. Left untreated, the patient may suffer loss of limbs because of the need to undergo amputation.

[0003] Treatment of such diseased arteries may include angioplasty or atherectomy. However, in some circumstances, these treatments are unsuitable, and an alternative solution is necessary. One such alternative solution is deep vein arterialisation (DVA), whereby blood flow is routed from the diseased artery to a nearby deep vein in order to supply the extremity with blood. Another possible treatment is an endovascular bypass procedure, whereby blood flow is routed out of the artery and back into the artery by a conduit that circumvents the blockage. That conduit may, for example, be a stent graft placed within an adjacent vein. The process of routing the blood from the artery to an adjacent vein involves the formation of a fistula, which is a passageway connecting the two vessels.

[0004] Conventional fistula systems usually involve the use of artery-vein crossover stent grafts. In these systems, a stent graft is secured across the artery wall and the vein wall toform a fistula. However, the implantation of these stents requires an involved and complex procedure, and may be accompanied by serious health complications.

[0005] Furthermore, conventional fistula systems carry the risk of ISS complications. Ischemic steal syndrome (ISS) is a complication that can occur after the construction of a vascular access (e.g., to treat a peripheral arterial disease or for the purpose of haemodialysis). The formation of a fistula changes the normal blood flow through the arteries to the smaller vessels in the extremities (e.g., hand or foot). If a large amount of blood passes directly from the artery into the vein this can lead to a reduced blood supply to the hand and fingers. This can result in cold, numb fingers, which may be painful. It can also reduce the blood supply to the nerves to the hand, which can reduce the strength in the hand. In extreme cases, it can cause tissue death (i.e., gangrene), which may result in the loss of fingers.

[0006] The present disclosure is directed to mitigating problems such as those described above and to provide an improved alternative to existing treatments. In particular, there is a need for improved devices, systems and methods to prevent or minimise the risk of ischemic steal syndrome. There is also a need for improved devices, systems and methods for the clinician to selectively divert blood flow towards the extremities. Further, there is a need for devices and systems which are less expensive and procedurally less complex than current systems and devices. There is also a need for improved devices and systems which are less likely to be displaced or to migrate within the subject’s vessel.SUMMARY

[0007] According to a first aspect of the disclosure, there is provided a stent device for forming a fistula between two vessels of a subject’s vascular system, said stent comprising a stent body including: a fluid passageway between a first end opening and a second end opening; at least one fistula opening configured to allow blood flow between two vessels of a subject’s vascular system; and an occlusion device configured to selectively close at least one of the first end opening or the second end opening.

[0008] In some embodiments, the stent comprises or is made of a flexible material. In some embodiments, the stent comprises or is made of one or more of an elastic material, an elastomeric material, a shape-memory material or memory alloy (such as nitinol).

[0009] In some embodiments, the stent comprises a radio-opaque material or component. In some embodiments, the radio-opaque component comprises a ring configured to surround a circumference of the stent body.

[0010] In some embodiments, the first end opening is a proximal end opening of the stent body, and the second end opening is a distal end opening of the stent body.

[0011] In some embodiments, the at least one fistula opening is positioned through a sidewall of the stent body.

[0012] In some embodiments, a plurality of fistula openings is disposed around a circumference of the stent body.

[0013] In some embodiments, the distance between the at least one fistula opening and the second end opening is greater than the distance between the at least one fistula opening and the first end opening.

[0014] In some embodiments, the occlusion device is configured to partially or completely close the first end opening of the stent body.

[0015] In some embodiments, the occlusion device is configured to adjust the inner circumference of the first end opening of the stent body.

[0016] In some embodiments, the occlusion device comprises a plurality of foldable leaves.

[0017] In some embodiments, the plurality of foldable leaves is disposed in an first end portion of the stent body. In some embodiments, the foldable leaves are disposed aroundthe circumference of the stent body, more particularly around the circumference of the end portion of the stent body.

[0018] In some embodiments, the foldable leaves form or extend from the end portion of the stent body.

[0019] In some embodiments, each leaf is foldable inwards towards the lumen of the stent body.

[0020] In some embodiments, the plurality of leaves comprises or is made of flexible material, elastic material, elastomeric material and / or shape-memory material.

[0021] In some embodiments, the plurality of leaves comprises or is made of the same or different material than that of the stent body.

[0022] In some embodiments, the plurality of leaves is integrally formed with the stent body.

[0023] In some embodiments, the occlusion device comprises a folding tool coupled to said plurality of foldable leaves and configured to adjust the extent of folding of the plurality of foldable leaves.

[0024] In some embodiments, the folding tool is configured to adjust the extent of folding of all the leaves in the plurality of leaves, of all the leaves in a sub-set of the plurality of leaves, or each leaf individually and separately from other leaves.

[0025] In some embodiments, the tool comprises a pull string or cord coupled to the plurality of foldable leaves. In some embodiments, the pull string or cord is coupled to all the leaves in the plurality of leaves, or of all the leaves in a sub-set of the plurality of leaves.

[0026] In some embodiments, the occlusion device defines a plurality of apertures.

[0027] In some embodiments, the plurality of apertures is disposed in the first end portion of the stent body. In some embodiments, the apertures are disposed around the circumference of the stent body. In some embodiments, the plurality of apertures is disposed around the circumference of the end portion of the stent body.

[0028] In some embodiments, the stent device further comprises a constricting tool coupled to said plurality of apertures and configured to selectively constrict the inner circumference of the first end opening of the stent body.

[0029] In some embodiments, the constricting tool comprises a string or cord loop coupled to the plurality of apertures.

[0030] In some embodiments, the occlusion device comprises a snap shut closure.

[0031] In some embodiments, the snap shut closure comprises one or more magnets. In some embodiment, the snap shut closure is configured to close upon application of pressure.

[0032] In some embodiments, the occlusion device comprises one or more valves.

[0033] In some embodiments, the stent device further includes a coating comprising one or more thrombolytic compounds.

[0034] According to a second aspect of the disclosure, there is provided a system comprising a stent device as described hereinabove.

[0035] In some embodiments, the system comprises an external control device configured to control the occlusion device.

[0036] In some embodiments, the system comprises one or anchors configured to prevent migration of the stent within the vessel.

[0037] According to a third aspect of the disclosure, there is provided a method for forming a fistula between two vessels of a subject’s vascular system, wherein the method comprises the steps of providing a stent device as described hereinabove in one vessel.

[0038] In some embodiments, the method comprising the step of forming a fistula.

[0039] In some embodiment, the method comprises the step of diverting fluid flow in a vessel.

[0040] In some embodiments, the method comprises the step of selectively closing at least one of the first end opening or the second end opening of the stent body.

[0041] In some embodiments, the method comprises the step of adjusting the inner circumference of at least one of the first end opening or the second end opening of the stent body.

[0042] According to a fourth aspect of the disclosure, there is provided a method for diverting flow in a vessel, wherein the method comprises the steps of providing a stent device as described hereinabove in one vessel.

[0043] According to further aspects of the disclosure, a stent device as described hereinabove is provided for the treatment of one or more of partial and complete obstructions, partial and complete occlusions, and chronic total occlusion (CTO). Obstructions or occlusions may consist of one or more of atherosclerotic or atherosclerotic related-lesions, calcific lesions, restenosis, acute, subacute or chronic blood clots, and embolus.

[0044] These and other features of the concepts provided herein will become more apparent to those of skill in the art in view of the accompanying drawings and the following description, which describe particular embodiments of such concepts in greater detail.BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic representation of a subject’s leg with a chronic total occlusion;

[0046] Figure 2 is a schematic representation of a stent device in situ in a subject’s vessel, according to one or more embodiments shown and described herein;

[0047] Figure 3 A is a schematic (side view) representation of the stent device of Figure 2 in an open configuration, according to one or more embodiments shown and described herein;

[0048] Figure 3B is a schematic (top view) representation of the stent device of Figure 2 in an open configuration, according to one or more embodiments shown and described herein;

[0049] Figure 4A is a schematic representation of the proximal end portion of the stent device of Figure 2 in a closed configuration (side view), according to one or more embodiments shown and described herein;

[0050] Figure 4B is a schematic representation of the proximal end portion of the stent device of Figure 2 in a closed configuration (top view), according to one or more embodiments shown and described herein;

[0051] Figure 5 is a schematic representation of the proximal end portion of a stent device according one or more embodiments shown and described herein;

[0052] Figure 6A is a schematic representation of the proximal end portion of a stent device according in an open configuration, according to one or more embodiments shown and described herein;

[0053] Figure 6B is a schematic representation of the proximal end portion of a stent device according in an open configuration, according to one or more embodiments shown and described herein;

[0054] Figure 6C is a schematic representation of the proximal end portion of a stent device according in an open configuration, according to one or more embodiments shown and described herein;

[0055] Figure 7 is a schematic representation of the proximal end portion of a stent device according in a closed configuration, according to one or more embodiments shown and described herein;

[0056] Figure 8A is a schematic representation of the proximal end portion of a stent device in an open configuration, according to one or more embodiments shown and described herein; and

[0057] Figure 8B is a schematic representation of the proximal end portion of a stent device in a closed configuration, according to one or more embodiments shown and described herein.DETAILED DESCRIPTION

[0058] The embodiments described herein are provided as exemplary and non-limiting embodiments of the present disclosure.

[0059] Within the context of the present disclosure, a vessel may be an artery or a vein. For example, in the case of an arteriovenous stent, the first vessel may be an artery, and the second vessel may be a vein, so that the fistula allows blood flow from the artery to the vein.

[0060] Within the context of the present disclosure, “proximal”, “a proximal end”, “a proximal portion”, “a proximal end portion”, and “a proximal length”, of for example astent body, designate an end, portion, end portion, length of the stent body intended to be nearer the heart of the subject, when the stent is at the intended fistula site.

[0061] Within the context of the present disclosure, “distal”, “a distal end”, “a distal portion”, “a distal end portion”, and “a distal length”, of for example a stent body, designate an end, portion, end portion, length of the stent body intended to be nearer the relevant extremity (e.g., hand or foot) and further from the heart of the subject, when the stent is at the intended fistula site. For example, if the stent is implanted in an artery in the left leg of the subject, the distal end is that closest to the left foot; if the stent is implanted in an artery in the right arm of the subject, the distal end is that closest to the right hand.

[0062] In the accompanying figures, the proximal side is designated by P and the distal side is designated by D.

[0063] Within the context of the present disclosure, an “end” of, for example a stent body, designates the terminal portion of the stent body. Within the context of the present disclosure, an “end portion” of, for example a stent body, designates the portion of the stent body, adjacent and including the end of the stent body.

[0064] With reference to Figure 1, there is illustrated a subject’s leg, with an artery 1 and a vein 2 located adjacent the artery 1. As illustrated, an obstruction 3 is located in the artery 1, in the form of a Chronic Total Occlusion (CTO), though other occlusions are contemplated and possible.

[0065] Figure 2 illustrates a stent device 100 for forming a fistula 4 between two vessels of a subject’s vascular system, said stent 100 comprising a stent body 101 defining a fluid passageway extending between a first end opening 102 and a second end opening 103; at least one fistula opening 104 configured to allow blood flow between two vessels 1, 2 of a subject’s vascular system; and an occlusion device 200 configured to selectively close at least one of the first end opening 102 or the second end opening 103. In this embodiment, the first vessel is an artery 1 and the second vessel is a vein 2, adjacent the artery 1.

[0066] As explained hereinabove, conventional fistula systems carry the risk of ISS complications. In order to address of these complications, it is known to use embolic devices, post-procedure. After the formation of the fistula, embolic devices may be strategically implanted in the vasculature in order to divert blood flow to one or more intended sites. However, a recurrent issue with embolic devices is the risk of displacement of embolic coils and plugs. Without adequate anchoring mechanisms or processes, the embolic devices may become dislodged and migrate. The implantation of occlusion devices adds to the procedural complexity, and to the overall cost of a fistula procedure.

[0067] The present stent device 100 may be used in a process for forming a fistula between two vessels 1,2 of a subject’s vasculature. The stent device 100 comprises an integrated occlusion device 200, which enables the clinician to selectively divert blood flow towards and through the first end opening 102 or the second end opening of the stent body 101. Therefore, the stent device 100 performs the dual function of a fistula device and of an occlusion device.

[0068] The stent device 100 may be positioned so that diverting blood flow towards and through the first end opening 102, diverts blood flow towards the heart; and so that diverting blood flow towards and through the second end opening 103, diverts blood flow towards an extremity. The extremity will depend on the location of the stent device 100. For example, of the stent device 100 is located in an arm, the extremity is the corresponding hand; of the stent device 100 is located in a leg, the extremity is the corresponding foot.

[0069] In this embodiment, the stent body 101 comprises a substantially tubular body. Whilst a substantially tubular contour is most suitable to vascular applications, it will be appreciated that other shapes and contours may be considered within the context of the present disclosure. The stent body 101 may be sufficiently flexible, so as to allow easy navigation through the subject’s vasculature, with minimal risk of injury. The stent body 101 may be sufficiently rigid, so as to preserve the structural integrity of the vessel in which it is implanted, in use, and so as to maintain blood flow through its fluid passageway.

[0070] The stent body 101 may be radially expandable so as to, on one hand, facilitate the delivery of the stent device 100 and, on the other hand, to fit against the inner wall of the vessel 2, around the target fistula site. This ability to radially expand allows the stent body 101 to be anchored to the target site in the vessel. Alternatively or additionally, the stent device 100 may comprise one or more anchors for anchoring to the vessel.

[0071] The stent body 101 may be made of or comprise one or more of a polymeric material, an elastomeric material, a rubber material and a shape-memory material or memory alloy (such as nitinol). Additionally or alternatively, the stent body 101 may be structured to be mechanically flexible. The stent body 101 may for example be of the type described in US 2006 / 0253190 Al, the content of which is incorporated herein by reference in its entirety.

[0072] The stent device 101 may comprise a radio-opaque material or component (Figure 4A). In some embodiments, the radio-opaque component 105 comprises a ring configured to surround a circumference of the stent body. In some embodiments, the radio-opaque ring is located in one or in each end portion of the stent body 101, or at one or at each end of the stent body 101. In some embodiments, the radio-opaque component 105 comprises one or more radio-opaque windows. For example, the fistula opening(s) 104 may comprise or may be outlined with radio-opaque material.

[0073] The first end opening 102 may be a proximal end opening configured to divert blood flow towards the heart of the subject; and the second end opening 103 may be a distal end opening configured to divert blood flow towards the extremity of the subject’s limb, in the embodiments illustrated in the figures, the foot.

[0074] The one or more fistula openings 104 are formed though the side wall of the stent body 101. Where the stent device 100 comprises a plurality of fistula openings 104, the fistula openings may be positioned around a circumference of the stent body 101. At least one fistula opening 104 is arranged and configured to be aligned with the fistula 4, so as to allow blood flow between the first vessel 1 and the second vessel 2 of the subject. Providing a plurality of fistula openings 104 assists the clinician in positioning the stent device 100 in working alignment relative to the fistula 4 in the vessel wall. A radio-opaquealignment marker may be provided on the stent body 101 and / or on the deployment system to allow the clinician to precisely align a fistula opening 104 of the stent device 100 with the fistula 4 in the vessel wall.

[0075] The fistula opening(s) 104 are located between the first end portion and the second end portion of the stent body 101. In some embodiments, the first end portion of the stent body 101 may be defined as the portion between the fistula opening(s) and the end of the stent body 101. In some embodiments, the fistula openings 104 are closer to the first end opening 102 than to the second end opening 103.

[0076] The occlusion device 200 is located in the proximal end portion or at the proximal end 102 of the stent body 101. The occlusion device 200 may be integrally formed with the stent body 101, or may be otherwise mechanically coupled to the proximal end 102 of the stent body 101. It will be appreciated that the occlusion device 200 may be located at the distal end portion of the stent body 101 or at the distal end of the stent body, or the stent device 100 may comprise the same or a different occlusion device 200 at each end of the stent body 101.

[0077] The occlusion device 200 may be configured to partially or completely close the end opening of the stent body 101. The extent of fluid passage through the end opening may be selectively and controllably adjusted between a state of substantially unhindered fluid passage and a closed state with no fluid passage. In some embodiments, the occlusion device 200 is configured to adjust the inner circumference of the end opening of the stent body 101, for example of the first end opening 102 of the stent body 101.

[0078] An embodiment of the occlusion device 200 is illustrated in Figures 3A and 3B, in which the occlusion device 200 comprises a plurality of foldable leaves 201 and a folding tool 202.

[0079] The foldable leaves 201 are disposed around the circumference of the first end opening 102. The foldable leaves 201 form the first end portion or extend from the first end 102 of the stent body 101. The foldable leaves 201 may be integrally formed with the stent body 101, or may be hingeably coupled to the stent body 101.

[0080] The leaves 201 may be folded at least radially inwards of the stent body 101, such as toward a centreline of the stent body 101. That is, the leaves 201 may fold from a first configuration in which they extend longitudinally from the end of the stent body 101 to a second configuration in which they are folded inwards to close the first end opening 102. As illustrated in Figures 4A and 4B, each leaf 201 is foldable inwards towards the lumen or fluid passageway of the stent body 101. The leaves 201 may comprise or be made of flexible material, elastic material, elastomeric material and / or shape-memory material. The leaves 201 may be made of the same or different material than that of the stent body 101.

[0081] In Figures 3 A and 3B, the leaves 201 are arranged around the first end opening 102, so as not to overlap with each other. Figure 5 illustrates an occlusion device 200 comprises two (or more) leaves 201 or wings, and the distal portion of the leaves 201 overlap with each other.

[0082] The extent of opening of the first end opening 102 may be adjusted by means of a folding tool. The folding tool may be coupled to one or more of the foldable leaves 201. The folding tool illustrated in Figures 3A and 3B include a pull string 202 or a pull cord. The pull string 202 is coupled to one or each foldable leaves 201, or to a subset of foldable leaves 201. The folding tool may comprise one or more pull strings 202. Each leaf 201 be connected to a separate pull string 202, may be opened or closed separately and independently to adjust the flow through the first end opening 102. Thus, the extent of fluid passage through the first end opening 102 may adjusted by adjusting the extent of folding of the leaves 201, and / or by adjusting the number of leaves 201 which are folded.

[0083] The folding tool may be coupled to a control device, external to the subject and adjustable by a user or clinician. The control device may control the extent of fluid passage through the first end opening 102, and thus the proportion of blood diverted towards the second end opening 103.

[0084] Figures 6A to 6C illustrate occlusion devices 200 comprising a plurality of apertures 203 and a constricting tool 204.

[0085] In these embodiments, the plurality of apertures 203 is disposed in the first end portion of the stent body 101. The apertures 203 may be disposed around the circumference of the stent body 101, for example in the end portion of the stent body 101, as illustrated for example in Figure 6C. In some embodiments, the apertures 203 may be located in the occlusion device 200, for example through the leaves 201, as illustrated in Figures 6A and 6B.

[0086] The structural integrity of the apertures 203 may be strengthened by means of reinforcing structures, such as eyelets, as seen for example in Figure 6C.

[0087] Figure 7 illustrates an occlusion device 200 without leaves 201 or wings, but with a plurality of apertures 203 and a constricting tool 204. In this embodiment, apertures 203 may be disposed around the circumference of the stent body 101, for example in the end portion of the stent body 101.

[0088] The constricting tool 204 is coupled to each aperture 203 and configured to selectively constrict the inner circumference of the first end opening 102 of the stent body 101. The constricting tool 204 comprises a string or cord loop coupled to (passing through) the apertures 203. Fluid passage through the first end opening 102 may be adjusted by pulling on one or both ends of the string or cord.

[0089] The constricting tool 204 may be coupled to a control device, external to the subject and adjustable by the user or clinician. The control device may control the extent of fluid passage through the first end opening 102, and thus the proportion of blood diverted towards the second end opening 103.

[0090] Figures 8A and 8B illustrates an occlusion device 200 with a snap shut-type closure. The occlusion device 200 may be opened or closed by means of one or more magnets. The snap shut closure may configured to close upon application of pressure or of magnetic force. The closure mechanism may be coupled to a control device, external to the subject and adjustable by the clinician.

[0091] Additionally or alternatively, the occlusion device 200 may comprises one or more valves, which may be communicatively coupled to a control device, external to the subject and adjustable by the clinician.

[0092] The stent device 100 may comprise or be coated with one or more pharmaceutically active compounds, for example a thrombolytic compound.

[0093] A system may be provided, which comprises a stent device 100 as described herein and one or more anchors configured to prevent migration of the stent within the vessel 2. Alternatively or additionally, the stent device 100 may comprise one or more anchors. The anchors may be mechanical anchors and / or chemical anchors. For example, the stent device 100 may be coated with a compound promoting the formation of tissues, so as to promote stabilisation of the stent device 100.

[0094] In an exemplary method, the stent device 100 is loaded into a delivery sheath so that, at the intended fistula site, the first end opening 102 is proximal to the heart of the subject and the second end opening 103 is distal relative to the heart. The stent device 100 is delivered, through the subject’s vascular system, to the intended fistula site. The position of the fistula may be selected based on the location of an obstruction 3 in a subject’s first vessel, such as an artery 1. The fistula is generally located upstream of the obstruction 3.

[0095] The stent device 100 is delivered to a second vessel, such as a vein 2, adjacent the first vessel, and may be secured at the intended site. For example, the stent device 100 may comprise one or more anchors, or may expand radially to be retain in the vessel by friction contact. The stent body 101 provides structural integrity around the fistula 4. The stent device 100 is arranged and configured to allow blood flow from a first vessel 1 to a second vessel 2, through a fistula opening 104 in the sidewall of the stent device 100. It will be appreciated that the stent device 100 is disposed in a single vessel. This is contrast with known fistula devices which are implanted across two vessels. The implantation procedure is therefore simpler, and the risk of associated trauma and complication is minimised.

[0096] The fistula opening 104 is aligned with the fistula opening 4, thereby becoming an inflow opening. Blood may flow from the artery 1 through the fistula opening 104, into thefluid passageway of the stent body 101, and towards the first end opening 102 and the second end opening 103. The first end opening 102 and the second end opening 103 become outflow openings.

[0097] If a large amount of blood passes directly from the artery 1 to the vein 2, the flow tends to be drawn towards the first (proximal) end opening 102, towards the heart, thereby resulting in a smaller amount being drawn towards the second (distal) end opening 103, towards the foot.

[0098] The proportion of blood flowing towards the respective end openings 102, 103 may be controlled by adjusting the first end opening 102 using the occlusion device 200, effectively acting as a flow diversion device. For example, the first end opening 102 towards the heart may be substantially closed to divert blood flow towards the extremity of the limb in which the stent device is implanted. The diversion may be permanent or temporary.

[0099] Thus, the present disclosure provides improved devices, systems and methods to prevent or minimise the risk of ischemic steal syndrome. The present disclosure also provides improved devices, systems and methods for the clinician to selectively divert blood flow towards the extremities. Further, the present disclosure provides devices and systems which are less expensive and procedurally less complex than current systems and devices. The present disclosure also provides improved devices and systems which are substantially non-migrating.ArteryVeinObstructionFistulaStent deviceStent bodyFirst end openingSecond end openingFistula openingRadio-opaque componentOcclusion deviceLeafFolding tool (string)ApertureConstricting tool (cord)

Claims

CLAIMS1. A stent device for forming a fistula between two vessels of a subject’s vascular system, said stent comprising: a stent body comprising: a fluid passageway between a first end opening and a second end opening; and at least one fistula opening configured to allow blood flow between two vessels of a subject’s vascular system; and an occlusion device configured to selectively close at least one of the first end opening or the second end opening.

2. The stent device of Claim 1, wherein the first end opening is a proximal end opening of the stent body, and the second end opening is a distal end opening of the tubular stent body.

3. The stent device of Claim 1 or 2, wherein the at least one fistula opening is formed through a sidewall of the stent body.

4. The stent device of any preceding claim, wherein a plurality of fistula openings a disposed around a circumference of the stent body.

5. The stent device of any preceding claim, wherein the distance between the at least one fistula opening and the second end opening is greater than the distance between the at least one fistula opening and the first end opening.

6. The stent device of any preceding claim, wherein the occlusion device is configured to partially or completely close the first end opening of the stent body.

7. The stent device of any preceding claim, wherein the occlusion device is configured to adjust the inner circumference of the first end opening of the stent body.

8. The stent device of any preceding claim, wherein the occlusion device comprises a plurality of foldable leaves.

9. The stent device of Claim 8, wherein the occlusion device comprises a folding tool coupled to said plurality of foldable leaves and configured to adjust the extent of folding of the plurality of foldable leaves.

10. The stent device of any preceding claim, wherein the occlusion device defines a plurality of apertures.

11. The stent device of Claim 10, further comprising a constricting tool coupled to said plurality of apertures and configured to selectively constrict the inner circumference of the first end opening of the stent body.

12. The stent device of any preceding claim, wherein the occlusion device comprises a snap shut closure.

13. The stent device of any preceding claim, wherein the occlusion device comprises one or more valves.

14. The stent device of any preceding claim, further including a coating comprising one or more thrombolytic compounds.

15. A method for forming a fistula between two vessels of a subject’s vascular system, wherein the method comprises the steps of providing a stent device of any preceding claim in one vessel.

16. The method of Claim 15, comprising the step of selectively closing at least one of the first end opening or the second end opening of the stent body.

17. The method of Claim 15 or 16, comprising the step of adjusting the inner circumference of at least one of the first end opening or the second end opening of the stent body.

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