Catheter for percutaneously creating an arteriovenous fistula and / or guidewire placement by itself in concomitant vessels

Abstract

The present disclosure provides a catheter (12) for percutaneously creating an arteriovenous fistula and / or guidewire placement by itself in concomitant vessels, the concomitant vessels being a vein (2) and an artery (4). The catheter comprises: an elongate body (14) dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion (16) and a distal portion (18), the distal portion having an end portion (20); and a lumen (25) extending through the elongate body for accommodating a guidewire (8). The catheter further comprises: an activatable cutting element (22) having a cutting surface (22a). The distal portion may comprise the activatable cutting element located at or in the vicinity of the end portion, wherein the cutting element is configured to deliver energy to a cutting site to create the fistula, wherein the activatable cutting element is arranged to be initially activated when the cutting element is located in the vein and before at least a portion of the cutting element is located the artery. Alternatively, the activatable cutting element (22) may be configured to be deployable and retractable through the lumen (25), wherein the cutting element is configured to deliver energy to a cutting site to create the fistula, wherein the activatable cutting element is arranged to be initially activated when the cutting element is located in the vein and before at least a portion of the cutting element is located the artery. A device comprising the catheter and a system comprising the device are also disclosed.

Description

[0001] CATHETER FOR PERCUTANEOUSLY CREATING AN ARTERIOVENOUS FISTULA AND / OR GUIDEWIRE PLACEMENT BY ITSELF IN CONCOMITANT VESSELS

[0002] Technical Field

[0003] This disclosure relates to a catheter for percutaneously creating an arteriovenous fistula and / or guidewire placement by itself in concomitant vessels. A system and device for the same are also disclosed. A method for percutaneously creating an arteriovenous fistula in concomitant vessels is also disclosed.

[0004] Background

[0005] Certain surgical procedures involve the creation of an arteriovenous fistula to connect an artery to a vein. For example, this may be performed in order for a patient to receive dialysis. By way of another example, this may be preformed for bypassing occluded arteries via a concomitant vein.

[0006] There is need in the art for a new type of catheter for creating an arteriovenous fistula.

[0007] Summary

[0008] According to a first aspect, there is provided a catheter for percutaneously creating an arteriovenous fistula and / or guidewire placement by itself in concomitant vessels, the concomitant vessels being a vein and an artery, the catheter comprising: an elongate body dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion and a distal portion, the distal portion having an end portion; a lumen extending through the elongate body for accommodating a guidewire; the catheter further comprising: an activatable cutting element, wherein the distal portion comprises the activatable cutting element located at or in the vicinity of the end portion, wherein the cutting element is configured to deliver energy to a cutting site to create the fistula, wherein the activatable cutting element is arranged to be initially activated when the cutting element is located in the vein and before at least a portion of the cutting element is located the artery.

[0009] By means of these features, it is possible for only one catheter (and one access into the patient) may be required in order to create the fistula. The catheter may allow a user to apply a forward mechanical force while the activatable cutting element is active, to aid in fistula creation. The elongate body may be configured with sufficient rigidity to allow the user to push the catheter through the vessels, with sufficient flexibility to enable the tip to align with the vessel wall.

[0010] The cutting element may be arranged to be initially activated when the entire cutting element is disposed in the vein.

[0011] The cutting site may be located in the vein. The cutting site may be a vein wall of the vein, and optionally, a portion of the vein wall closest to the concomitant artery.

[0012] The concomitant vessels may be substantially parallel to one another and / or adjacent to one another. The concomitant vessels may abut one another.

[0013] The vein and artery may, by way of non-limiting example, be any of: the posterior tibial artery / vein, anterior tibial artery / vein, peroneal artery / vein, radial artery / vein, ulnar artery / vein, or brachial artery / vein.

[0014] The elongate body may have a degree of rigidity to allow the activatable cutting element to be pushed through the vessels during activation and have a degree of flexibility to enable the distal portion to bend so as to be in alignment with a wall of at least one of the vessels.

[0015] The catheter may be configured to create the fistula prior to advancing the catheter into the artery. The catheter may have sufficient rigidity to enable a forward mechanical force to be applied to the catheter while the cutting element is activated.

[0016] The catheter may comprise a curved lumen for biasing the cutting element against the vessel wall at the cutting site. This may reduce an amount of bending required of the end portion when it comes proximate to the cutting site.

[0017] This curved lumen may assist in aligning the activatable cutting element with the wall of the vessel where the fistula is to be created.

[0018] The curved lumen may be formed by an inner surface of the lumen which is formed so as to cause the guidewire to deflect from a straight path; wherein the inner surface is disposed on a side of the catheter opposite the cutting element. That is, the curved lumen may deflect the guidewire away from a central longitudinal axis of the catheter. This curved lumen may therefore ensure the guidewire extends from the end portion of the distal portion at an angle from the end portion, so that the cutting element is positioned against the vein at the cutting site.

[0019] The guidewire may be relatively firmly fixed in place at the location where it crosses through the vein wall into the artery. When the distal end of the catheter advances close to this crossing location, the catheter may bend to directly face the wall of the vein at this location.

[0020] The activatable cutting element may comprise an annular surface.

[0021] The activatable cutting element may circumscribe the guidewire. That is, the guidewire may extend through the center of the annular surface of the activatable cutting element.

[0022] In this way, the activatable cutting element may circumscribe the guidewire and may form a fistula at a location centered upon the guidewire.

[0023] The cutting site may be at the location where the catheter accesses the artery to form the fistula at this location.

[0024] The end portion may be a tip of the catheter, i.e. a distalmost end of the catheter.

[0025] A cross-section of the activatable cutting element may be substantially the same as a cross-section of the distal portion of the elongate body. In this manner, elongate body may follow the activatable cutting element as it cuts further through from the vein to the artery.

[0026] The activatable cutting element may comprise an electrode, for example a single monopolar electrode. The activatable cutting element may one of: one or more spoke electrodes, a spiral electrode; and / or one or more ring electrodes.

[0027] The catheter may comprise a power connection for applying energy, supplied from a power source, to the activatable cutting element.

[0028] The power connection may be disposed at the proximal portion.

[0029] The activatable cutting element may extend beyond and / or be flush with at least one of an outer surface of the elongate body and an inner surface of the elongate body. The distal portion may comprise a tapered portion tapered towards and including the end portion.

[0030] The cutting element may be disposed on the tapered portion.

[0031] The distal portion may comprise a bent tip and the cutting element may be disposed on or in the bent tip, wherein the tip is bent so that the cutting element is placeable against a wall of the vein at the cutting site.

[0032] The cutting element may be formed on at least one of an end surface of the end portion and on a side surface of the end portion.

[0033] The distal portion may have a bevel shaped portion with respect to a central longitudinal axis of the elongate body.

[0034] The cutting element may be located on or in the bevel shaped portion. In this manner, the activatable cutting element (or at least a surface of the activatable cutting element) may be arranged at an angle to central longitudinal axis of the catheter. For example, the surface may be arranged approximately 45 degrees to the longitudinal central axis of the catheter.

[0035] The catheter may follow a curved (i.e. tortuous) path within the vein. The aforementioned central longitudinal axis should therefore be determined locally over a relatively short section of the catheter at the end portion.

[0036] The cutting element may be diamond-shaped and surround the lumen.

[0037] The cutting element may be oval-shaped and surround the lumen.

[0038] According to a second aspect, there is provided a catheter for percutaneously creating an arteriovenous fistula by itself in concomitant vessels, the concomitant vessels being a vein and an artery, the catheter comprising: an elongate body dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion and a distal portion, the distal portion having an end portion; a lumen extending through the elongate body for accommodating a guidewire; the catheter further comprising: an activatable cutting element, wherein the activatable cutting element is configured to be deployable and retractable through the lumen, wherein the cutting element is configured to deliver energy to a cutting site to create the fistula, wherein the activatable cutting element is arranged to be initially activated when the cutting element is located in the vein and before at least a portion of the cutting element is located the artery.

[0039] The cutting element may comprise an umbrella element having a plurality of spokes.

[0040] The catheter may further comprise a deployment element for deploying the umbrella.

[0041] In this manner, the deployment (unfurling) and retraction (re-furling, after use) of the umbrella may be controlled manually by the user.

[0042] The deployment element may comprise a rigid push rod. This may allow a user to push an end of the rigid push rod that is outside the patient (e.g. on a handle connected to the catheter) to deploy the umbrella.

[0043] The umbrella may be configured to transition between a folded state, in which state the umbrella may fit within the lumen, and at least one of an expanded state and a partially expanded state.

[0044] This may allow the umbrella to be protected by the catheter body while the catheter is being advanced along a vessel (e.g. vein), to avoid damage to either of the vessel and the umbrella.

[0045] The activatable cutting element may be configured to be disabled while the umbrella is within the lumen. This may prevent damage to the catheter due to unintentional activation of the activatable cutting element.

[0046] The activatable cutting element may comprise one or more cutting electrodes.

[0047] The one or more spokes may constitute the one or more cutting electrodes. That is, the spokes may serve a dual purpose of providing shape to the umbrella (and deploying / furling it too) and providing the activatable cutting element.

[0048] The one or more spokes may be flexible.

[0049] The one or more spokes comprise nitinol wire.

[0050] A state of deployment of the umbrella (i.e. folded state or expanded or partially expanded state) may be manually or automatically adjustable. This state of deployment may, at least partially, depend on at least one of the location of the concomitant vessels and the dimensions of the concomitant vessels).

[0051] At least one of the distal portion and the end portion may comprise one or more visualisation aids, wherein the visualisation aids are configured to allow the catheter to be visualized by a detection device, for example, an ultrasound device.

[0052] This may optionally allow easier identification of the location of the end portion and / or activatable cutting element, to ensure it is correctly located at the intended location before (and, optionally, while) cutting energy is applied.

[0053] The one or more visualisation aids may comprise one or more cutouts. That is, sections of the material of the catheter may be removed to provide a clearly-identifiable change in the outer profile of the catheter at a known location.

[0054] The catheter may comprise one or more reinforcement elements for reinforcing the catheter arranged to compensate for material absent in the one or more cutouts.

[0055] The one or more visualisation aids and / or the one or more reinforcement elements may be arranged circumferentially around the catheter.

[0056] The one or more reinforcement elements may comprise one or more reinforcement splines, respectively. These splines may optionally compensate for the loss of strength caused by removing material of the catheter to form the cutouts, thereby ensuring the overall catheter does not have “weak spots” along its length.

[0057] The one or more reinforcements splines may comprise metal. Alternatively, the catheter may comprise pebax and the reinforcement splines may comprise a higher durometer pebax.

[0058] The one or more reinforcement elements may comprise a metal braid, wherein the metal braid is disposed at the one or more locations of the one or more cutouts.

[0059] The metal braid may provide a different visual texture of the catheter, e.g. under ultrasound, to allow the catheter to be more clearly identified by a detecting device.

[0060] The one or more cutting electrodes may be arranged as at least one of: one or more spoke electrodes, a spiral electrode; and / or one or more ring electrodes. The one or more electrodes may be arranged on a distal-facing surface of the umbrella when the umbrella is in the expanded or partially expanded state. That is, the electrodes may be arranged on an outer facing surface of the umbrella, i.e. on a surface of the umbrella that is away from the catheter.

[0061] The one or more spokes may be arranged so that each of the one or more electrodes sits within a respective groove of the umbrella material. In this manner, each of the one or more electrodes is shielded by an umbrella material of the umbrella. Such grooves might, however, only be apparent during the deployed state of the umbrella.

[0062] The umbrella material may be silicon or pebax or other insulative flexible material suitable for use inside the human body.

[0063] The one or more electrodes is arranged to be deployed prior to the initial activation of the cutting element from a folded state of the umbrella element to an expanded or partially expanded state.

[0064] The catheter may be 4-7 French (1 .3 mm to 2.3mm).

[0065] A placement of the guidewire may follow a path of a needle tip which is arranged to cross the vein and the artery in one operation.

[0066] The activatable cutting element may use at least one of radiofrequency ablation, thermal, laser, microwave and cryogenic energy to gain the access.

[0067] The guidewire may be deployable out of, and retractable through, the lumen.

[0068] When the guidewire is deployed, a distal end of the guidewire may extend beyond the end portion of the catheter.

[0069] According to a third aspect, there is provided a device for creating an arteriovenous fistula and / or guidewire placement in concomitant vessels, the device comprising any catheter as described hereinabove.

[0070] The device may further comprise: a handle, the handle comprising: a steering element for steering the distal portion of the catheter in a direction, for example, towards the cutting site. The handle may further comprise a button or slider for activating the deployment element (if present). The steering element may comprise at least one of mechanical and pneumatic actuators.

[0071] The device may further comprise: a sheath for accommodating the catheter, wherein the sheath comprises a lumen through which the catheter is advanceable.

[0072] The device may further comprise a guidewire.

[0073] The guidewire may be arranged to maintain access from the vein to the artery. The guidewire may further guide the catheter and activatable cutting element to the intended location for forming the fistula.

[0074] The catheter may be a single catheter. That is, only a single catheter may be required in order to create the fistula between vein and artery.

[0075] According to a further aspect, there is provided a system for creating an arteriovenous fistula and / or guidewire placement in concomitant vessels, the system comprising: the device according to the third aspect.

[0076] The system may further comprise a needle element arranged to puncture through the vein and artery to allow the guidewire access to the artery.

[0077] The needle element may be arranged to gain an initial access through the vein and artery in an access region in a single operation.

[0078] The cutting element may then be arranged to expand the access region.

[0079] The system may further comprise: a non-invasive detection system for detecting the location of the catheter, in use. The non-invasive detection system may be, for example, an ultrasound system.

[0080] According to a further aspect, there is provided a method for percutaneously creating an arteriovenous fistula in concomitant vessels, the concomitant vessels being a vein and an artery. The method comprises: inserting a guidewire percutaneously such that the guidewire extends from a vein into an artery; inserting a catheter over the guidewire and into the vein, the catheter comprising: an elongate body dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion and a distal portion, the distal portion having an end portion; a lumen extending through the elongate body for accommodating the guidewire; an activatable cutting element located at or in the vicinity of the end portion; the method further comprising: advancing the catheter along the guidewire until the end portion is adjacent a point where the guidewire exits the vein and enters into the artery; and activating the activatable cutting element and advancing the activatable cutting element along the guidewire to form a fistula between the vein and the artery.

[0081] In the method, the catheter may be the catheter according to the first or second aspects.

[0082] The step of inserting a guidewire may include inserting a needle element through the skin, into the vein and through the vein into an artery; inserting the guidewire through the needle; and withdrawing the needle proximally over the guidewire. Withdrawing the needle may comprise leaving the guidewire in place while the needle is removed from the patient and then advanced proximally over the guidewire until the guidewire is no longer within the needle.

[0083] Prior to the step of activating the activatable cutting element, the method may further comprise deploying an umbrella that comprises the activatable cutting element from the lumen, and transitioning the umbrella from a furled state to an expanded or partially expanded state.

[0084] Brief Description of the Drawings

[0085] Reference will now be made, by way of example only, to the accompanying drawings in which:

[0086] Figure 1A shows a schematic side-on view of a catheter penetrating a vein and an artery;

[0087] Figure 1 B shows a plan view of the catheter penetrating a vein and an artery as depicted in Figure 1A;

[0088] Figure 2A shows a schematic side-on view of a sheath penetrating in the vein, and the catheter extending out from the sheath and along a guidewire;

[0089] Figure 2B shows a zoomed-in view of a distal end portion of the catheter;

[0090] Figure 3A shows a perspective view of a tip of the catheter;

[0091] Figure 3B shows a side-on view of the tip of the catheter of Figure 3A; Figure 4A shows a perspective view of another design of the tip of the catheter;

[0092] Figure 4B shows the perspective view of Figure 4A with the guidewire extending out from the catheter;

[0093] Figure 5A shows a perspective view of another design of the tip of the catheter;

[0094] Figure 5B shows a cross-sectional side view of the catheter of Figure 5A;

[0095] Figure 6 shows a catheter having an umbrella extendable from the tip;

[0096] Figures 7A-D show various designs for cutting elements arranged on the umbrella;

[0097] Figures 8A and 8B show an end portion of the catheter having cutouts; and

[0098] Figure 9 shows an end portion of the catheter having a metal braid over the cutout.

[0099] Description

[0100] Figure 1A shows a schematic view of a concomitant vein 2 and artery 4. By way of non-limiting example, the vein and artery could be any of the posterior tibial artery / vein, anterior tibial artery / vein, peroneal artery / vein, radial artery / vein, ulnar artery / vein, or brachial artery / vein. A needle element comprising a needle 6 is used to insert a guidewire 8. To do this, the needle 6 is inserted percutaneously to penetrate first into the vein 2 and then into the artery 4. The guidewire 8 is inserted, through the needle 6, into the artery 4 and the needle 6 is then removed. The guidewire 8 remains in position, crossing out of the vein 2 at a location Z in the wall 2a of the vein 2 and then entering the artery 4.

[0101] Figure 1 B shows a different perspective of the schematic view of Fig 1 A.

[0102] Figure 2A shows a device 1 comprising, inter alia, a sheath 10 for introducing a catheter 12 into the vein 2. The catheter 12 has an elongate body 14 having a proximal portion 16 (N.B. the proximal portion 16 of the catheter 12 is, in Figure 2A, located inside the sheath 10) and a distal portion 18. The elongate body 14 forms a tube having a lumen 25 (shown in Figures 3A, 4A, 5A, etc.) Typically, the tube will have a substantially circular cross-section, but other cross-sections are envisaged. At a proximal end of the sheath 10, there is a handle 3 comprising a steering element 3a for steering the distal portion 18 of the catheter 12. The steering element 3a may comprise mechanical and / or pneumatic actuators.

[0103] Together, the device 1 , the guidewire 8 and the catheter 12 according to any of the examples disclosed herein constitute a system for creating an arteriovenous fistula. The system may be considered to further comprise the needle element. The system may further comprise a non-invasive detection system 50 for detecting the location of the catheter in use, such as an ultrasound system.

[0104] The terms “distal” and “proximal” used herein take their usual meanings in the art. That is, the “distal” refers to parts / regions located furthest from the care provider and “proximal” refers to parts / regions closest to the care provider. Thus, when the catheter 12 is in use, the distal portion 18 of the catheter 12 may be located inside the patient’s vasculature (e.g. vein 2), while the proximal portion 16 may be outside the patient’s body and may be manipulated by a physician or other care provider.

[0105] The distal portion 18 has an end portion 20 and comprises an activatable cutting element 22 located at or in the vicinity of the end portion 20. In some catheter 12 designs, the activatable cutting element 22 is at a fixed position relative to the elongate body 14. For example, the activatable cutting element 22 may be formed in / integral with the elongate body 14 of the catheter 12. In other designs of catheter 12, the activatable cutting element 22 may be movable relative to the elongate body 14. For example, the activatable cutting element 22 may be initially stored within the elongate body 14 and then extended out therefrom before activation. Details of these various designs are discussed in further detail below.

[0106] The activatable cutting element 22 is for forming a fistula of a predetermined size between the vein 2 and artery 4 using an ablation technology. The activatable cutting element 22 may, by way of non-limiting example, employ any of: radiofrequency, thermal, laser, microwave, and / or cryogenic ablation technologies for forming the fistula. The activatable cutting element 22 may be connected to power source 60 outside the patient via a wire, lumen or fiber (not shown) running through the elongate body 14. For example, the power source 60 may provide, via a wire, electrical power having a radio frequency alternating current. Alternatively, the power source 60 may provide laser energy along an optical fibre. Alternatively, the power source 60 may be configured to provide a coolant (such as liquid nitrogen) along a lumen for performing cryogenic ablation. Cryogenic ablation may also be provided as a spray within a balloon. The activatable cutting element 22 may comprise an electrode, for example a single monopolar electrode.

[0107] The activatable cutting element 22 may be said to have a cutting surface 22a from which the cutting energy is emitted. Thus, for example, if the activatable cutting element 22 is laser-based, then the cutting surface 22a may be a lens or the end of a fiber optic from which the laser energy is emitted. By way of another example, if the activatable cutting element 22 utilises thermal energy or radiofrequency energy, the cutting surface 22a may be any and all surface(s) of the activatable cutting element 22 that face towards the wall 2a in which the fistula is to be formed.

[0108] The proximal end 16 of the catheter may be connected to the power supply 60, optionally via the handle 3, for selectively supplying power to the activatable cutting element 22.

[0109] In use, the catheter 12 is inserted into the vein 2 and advanced along the guidewire 8 to the location Z within the vein 2. The activatable cutting element 22 is then pressed against the wall 2a of the vein 2 at the location Z and is activated. Activating the activatable cutting element 22 involves applying one of the aforementioned forms of energy to the activatable cutting element 22.

[0110] The elongate body 14 may have a degree of rigidity to allow the activatable cutting element 22 to be pushed through the vessels during activation and may have a degree of flexibility to enable the end portion to bend so as to be in alignment with a wall 2a of the vessel.

[0111] When activated, the activatable cutting element 22 ablates tissue at location Z. The catheter 12 can then be advanced further as it ablates further tissue between the vein 2 and artery 4 until the catheter 20 has formed a fistula between the vein 2 and artery 4. As the catheter 12 is advanced, it follows the path defined by the guidewire 8 from the vein 2 into the artery 4.

[0112] Ablation technologies may reduce the trauma involved in forming the fistula compared to a mechanical piercing member.

[0113] After forming the fistula, the catheter 12 can be removed from the patient’s vasculature. The elongate body 14 of the catheter 12 may be configured to have a degree of rigidity to allow the activatable cutting element 22 to be pushed through the vessels (i.e. from the vein 2 through to the artery 4) during activation and to have a degree of flexibility to enable the distal portion 18 to bend so as to be in alignment with a wall of at least one of the vessels (e.g. to align with the wall 2a of the vein). That is, the rigidity of the catheter 12 may be selected according to an intended use case, to balance the aforementioned requirements. This may be selected by choosing a suitable material (e.g. selecting Pebax having the desired durometer) for the catheter body and / or by determining the catheter 12 size / diameter (e.g. measured in French).

[0114] Various different forms of the activatable cutting element 22 and end portion 20 are described below in relation to Figures 3A to 9. Each of these different designs may be used in the manner described hereinabove. In the following description, where features are the same as those described hereinabove, like reference numerals will be used.

[0115] Figures 2B and 3B depict the distal portion 16 having a bevel shaped portion 24. Figure 3A shows a side-on view of the end portion of the catheter 20 that is depicted in Figure 2B, the side-on view generally facing towards the bevel shaped portion 24. The activatable cutting element 22 is located on or in the bevel shaped portion 24 and has a generally diamond-shaped cross section that surrounds a lumen 25 of the catheter 12. In use, the guidewire 8 extends through the lumen 25.

[0116] The activatable cutting element 22 shown in Figures 3A and 3B has a generallyannular surface defined within a plane P. The end portion 20 of the catheter defines a central longitudinal axis X and, when the catheter is advanced through a patient’s vasculature, the end portion 20 will advance along the central longitudinal axis X. The plane defines a normal N, and an angle a is defined between the normal N and the axis X. For a bevelled edge, such as shown in Figure 3B, a may be between 10 and 80 degrees. The activatable cutting element 22 may be located on or in this bevel shaped portion and its surface may be flush with or extending from the bevelled edge.

[0117] Figure 3A depicts a catheter 12 where the activatable cutting element 22 is flush with the outer surface of the elongate body 14.

[0118] Figure 4A depicts a catheter 12 where the activatable cutting element 22 is located on the distalmost end of the elongate body 14, such that the activatable cutting element 22 may be said to extend beyond the elongate body 14. In the catheter 12 shown in Figure 4A, the activatable cutting element 22 has an annular surface. In this Figure the cross-section of the activatable cutting element 22 is substantially the same as a cross- section of the distal portion 18 of the elongate body 14. That is, in this catheter 12, the elongate body 14 is generally annular in cross-section (with the guidewire 8 extending through the center of the annulus) and the activatable cutting element 22 is also annular in cross-section.

[0119] Figure 4A depicts a catheter 12 having an end portion 20 that is not bevelled. That is, a plane defined by the end of the catheter 12 is perpendicular to the central axis X. In other words, for this end, the angle a defined between the normal and the central axis is less than 10 degrees (i.e. a<10) and is preferably 0 degrees. In Figure 4A, the elongate body 14 has a circular cross section and the activatable cutting element 22 is annular.

[0120] Figures 5A and 5B depict a catheter 12 wherein the activatable cutting element 22 is located on a side of the catheter 12 at the end portion 20. In this embodiment, the plane P defined by a surface of the activatable cutting element 22 is generally parallel to and spaced apart from the central axis X. That is, the angle defined between the normal N to the surface and the central axis X of the elongate body 18 is greater than 80 degrees and is preferably 90 degrees. This arrangement means that when the axis X is locally aligned along a central axis of a blood vessel in which the catheter 12 is advancing, the activatable cutting element 22 faces directly towards a wall of the blood vessel (e.g. faces towards wall 2a).

[0121] In Figures 5A and 5B, the activatable cutting element 22 defines an aperture therethrough, on the side of the catheter, and the guidewire 8 exits the lumen 25 through the aperture defined by the activatable cutting element. That is, the guidewire 8 exits out of a side of the catheter 12. The guidewire 8 is deflected from the longitudinal central axis X of the distal portion 18 by the lumen 25 being curved (i.e. biased) towards the end. An inner surface 25a of the lumen, opposite to the activatable cutting element 22, curves towards the longitudinal central axis X and towards the aperture formed by the activatable cutting element 22. The guidewire 8 is therefore curved off (i.e. biased away from) the longitudinal central axis X and out of the aperture on the side of the catheter 12.

[0122] In use, after the guidewire 8 has been inserted, as described above, the guidewire 8 extends along a central axis of a vein, then bends towards the vein wall 2a at the location Z where it crosses to the vein 4. With the catheter 12 of Figures 5A and 5B, the end portion 12 does not need to bend much or at all when it reaches the location Z because the catheter 12 can extend generally parallel to a longitudinal axis of the vein (note: both the vein and catheter may follow a curved path) while the activatable cutting element, which circumscribes the guidewire 8, is already facing the wall 2a of the vein. Thus, the curved inner surface 25a of the lumen 25 is formed so that when the guidewire extends from the end portion 20 of the distal portion 18, the guidewire extends at an angle from the end portion, so that the cutting element is positioned against the vein wall 2a at the cutting site.

[0123] The catheter 12 depicted in Figure 5A has a tapered portion at the distal portion 12, tapered towards and including the end portion 20 and the activatable cutting element 22.

[0124] Figure 6 depicts a catheter 12 having an activatable cutting element 22 that is movable relative to the end portion 20 of the catheter 12. The activatable cutting element 22 is formed on an umbrella 26 (also called umbrella element 26). The umbrella 26 may be in a furled configuration during insertion of the catheter 12 and during advancement of the catheter 12 through a vasculature to the location X. The guidewire 8 may extend through a centre of the umbrella 26. The umbrella 26 has an apex 28 and spokes 30 extending generally outward from the apex 28. Umbrella material 32 is located between each of the spokes 30. The umbrella material 32 may be any non-conductive insulative material, for example silicon or pebax, which is a thermoplastic elastomer comprising a block copolymer.

[0125] The spokes 30 may be flexible. The umbrella material 32 that is located between each of the spokes 30 may be sized such that, when the umbrella 26 is furled, the spokes 30 are straight and lie generally parallel to the guidewire 8 at the distal end of the catheter, and such that, when the umbrella 26 is unfurled, the spokes 30 are bent such that the umbrella 26 defines a dome shape.

[0126] Alternatively, the spokes 30 may be rigid and / or the umbrella material 32 may be sized such that the spokes 30 remain essentially straight when the umbrella 26 is unfurled. In this case, the umbrella 26 forms a cone shape when unfurled.

[0127] The spokes 30 may be made of ninitol which is a metal alloy of nickel and titanium. Typically, the metals in ninitol are in roughly equal proportions, for example Ninitol 60 consists of 60wt.% nickel and 40wt.% titanium plus unavoidable impurities.

[0128] The umbrella 26 may be stored within the lumen 25 of the catheter 12 before it is to be used. When the catheter 12 is in place near location X, the umbrella 26, having the activatable cutting element 22, is extended out from the lumen 25 where it unfurls (i.e. deploys). Alternatively, the umbrella 26 may sit immediately adjacent the end portion 20 of the catheter 12 (i.e. not within the lumen itself), in a furled state, during advancement of the catheter 12 through a vasculature. The umbrella 26 may be arranged such that the apex 28, at a radial center of the umbrella 26, is the distalmost part of the umbrella 26, while an outer circumferential edge of the umbrella 26 is generally proximal of the radial center. Put another way, the umbrella 26, when unfurled, may generally “point towards” the intended fistula location Z.

[0129] The umbrella 26 may be manually deployed by a deployment element, such as a rigid push rod 26a. The control for the deployment element may be located on the handle 3 in the form of a button or slider for example. By use of the push rod 26a (or other deployment element), the umbrella 26 may be partially or fully unfurled by a user, e.g. when the catheter is in position and the end portion is generally adjacent the intended fistula location Z. The umbrella 26 may also be configured to automatically unfurl when moved out of the lumen 25. For example, the umbrella 26 may be spring-biased to a deployed position, and only held in the furled position by the lumen 25 it is within. In such designs, the deployment element may be used to re-furl the umbrella 26 for retraction back into the catheter 12 after the fistula has been formed. Alternatively, the umbrella may comprise a shape memory alloy, such that the umbrella unfurls automatically.

[0130] The activatable cutting element 22 may be configured such that it may only be activated once the umbrella 26 is outside the lumen 25 - this position may be termed the “activated state”. Before this, i.e. in a “pre-activated state”, the activatable cutting element may be prevented from activating. This may prevent damage to the catheter 12 from accidental (premature) activation of the activatable cutting element 22 when it is still within the lumen 25.

[0131] The activatable cutting element 22 shown in Figures 7A-D may be formed on the umbrella 26. The umbrella 26 may therefore have one or more cutting elements disposed on its outer surface, the outer surface being the surface facing towards the wall 2a at the intended fistula location Z when the umbrella 26 is deployed. That is, the outer surface may be the most-distal surface of umbrella, i.e. away from the catheter 12. These cutting elements, taken together, form the activatable cutting element 22. For example, the cutting elements may be one or more cutting electrodes 34a-c. For example, the cutting elements may take any of the following forms:

[0132] • multiple linear electrodes 34a, each extending generally radially outwards from the apex 28 of the umbrella 26 - see for example Figure 7A. In this case, the linear electrodes may themselves form the spokes 30 of the umbrella 26. • a spiral electrode 34b having a centre of the spiral located at or near the apex 28 of the umbrella 26 - see for example Figure 7B.

[0133] • one ring electrode centred around the apex 28, or multiple concentric ring electrodes 34c, each having a different diameter and each being centred around the apex 28 of the umbrella 26 - see for example Figure 7C,

[0134] Figure 7A shows an end-on view of one example of the umbrella 26. The linear electrodes 34c shown in Figure 7A may be recessed, as shown in Figure 7D which is a cross-section through the umbrella 26 of Figure 7A. In this case, the umbrella material 32 is generally radially outward of the linear electrodes 34a at each location axially along the electrodes 34a. That is, the linear electrodes are recessed within grooves 36 within the umbrella material 32. The linear electrodes 34a may thereby be arranged so that they are shielded by the umbrella material 32.

[0135] Figures 8A and 8B show side views of the end portion 20 of the catheter 12. In these figures, the end portion 20 has a bevel shaped portion 24. However, the features described below are not limited to catheters 12 having a bevel shaped portion 24, and these features may be used with any of the catheter 12 designs described herein.

[0136] Figures 8A and 8B show the catheter 12 with cutouts 38 intended to aid visualisation of the catheter under ultrasound tracking. The cutouts 38 are areas where material of the catheter 12 has been removed so as to form an identifiable notch in the catheter 12 near its distal end. These may optionally allow a user of the catheter 12 to easily identify a given location near the distal end of the catheter 12 from an image generated by the visualisation system 50 (e.g. an ultrasound image). This may allow the user to identify when the end portion 20 of the catheter 12 is in the correct location before beginning the operation to form the fistula at location Z.

[0137] One or more reinforcement splines 40 may be formed crossing the cutouts 38. This may ensure the catheter 12 has sufficient bodily integrity despite the cutouts 38. The reinforcement splines 40 may optionally be formed of metal (such as ninitol) or a polymer material having a different (higher) durometer than the material of the catheter 12. For example, the polymer may be (higher durometer) pebax. The reinforcement splines 40 may be arranged circumferentially around the catheter 12.

[0138] Figure 9 shows the end portion 20 having cutouts 38, where the cutouts have been reinforced with a braid 42. The braid may provide a different visual texture under ultrasound imaging, such that the location of the cutouts 38 I the braid 42 is clearly identifiable under ultrasound imaging. The braid 42 may be a metal braid, made of ninitol, for example, or may be a braid made from a pebax material of higher durometer than the material of the catheter 12.

[0139] List of References

[0140] Device 1

[0141] Vein 2

[0142] Vein wall 2a

[0143] Handle 3

[0144] Steering element 3a

[0145] Artery 4

[0146] Needle 6

[0147] Guidewire 8

[0148] Sheath 10

[0149] Catheter 12

[0150] Elongate body 14

[0151] Proximal portion 16

[0152] Distal portion 18

[0153] End portion 20

[0154] Activatable cutting element 22

[0155] Surface 22a

[0156] Bevel shaped portion 24

[0157] Lumen 25

[0158] Umbrella 26

[0159] Apex (of umbrella) 28

[0160] Spokes (of umbrella) 30

[0161] Umbrella material 32

[0162] Electrodes 34a-c

[0163] Grooves 36

[0164] Cutouts 38

[0165] Reinforced splines 40

[0166] Metal braid 42

[0167] Detection system 50

[0168] Power source 60

[0169] Central axis (of end portion) X Plane of surface P

[0170] Normal (of surface) N

[0171] Angle between P and N a

[0172] Intended fistula location Z

Claims

Claims1 . A catheter for percutaneously creating an arteriovenous fistula and / or guidewire placement by itself in concomitant vessels, the concomitant vessels being a vein and an artery, the catheter comprising: an elongate body dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion and a distal portion, the distal portion having an end portion; a lumen extending through the elongate body for accommodating a guidewire; the catheter further comprising: an activatable cutting element, wherein the distal portion comprises the activatable cutting element located at or in the vicinity of the end portion, wherein the cutting element is configured to deliver energy to create the fistula, wherein the activatable cutting element is arranged to be initially activated when the cutting element is located in the vein and before at least a portion of the cutting element is located in the artery.

2. The catheter according to claim 1 , wherein the catheter comprises a curved lumen for biasing the cutting element against the vessel wall at the cutting site.

3. The catheter according to claim 2, wherein the curved lumen is formed by an inner surface of the lumen which is formed so as to cause the guidewire to deflect from a straight path; wherein the inner surface is disposed on a side of the catheter opposite the cutting element.

4. The catheter according to any preceding claim, wherein the activatable cutting element comprises an annular surface.

5. The catheter according to any preceding claim, wherein a cross-section of the activatable cutting element is substantially the same as a cross-section of the distal portion of the elongate body.

6. The catheter according to any preceding claim, wherein the cutting element comprises an electrode, for example a single monopolar electrode.

7. The catheter according to any preceding claim, wherein the cutting element extends beyond and / or is flush with at least one of an outer surface of the elongate body and an inner surface of the elongate body.

8. The catheter according to any preceding claim, wherein the distal portion comprises a tapered portion tapered towards and including the end portion.

9. The catheter according to any preceding claim, wherein the cutting element is disposed on the tapered portion.

10. The catheter according to any preceding claim, wherein the distal portion comprises a bent tip and the cutting element is disposed on or in the bent tip, wherein the tip is bent so that the cutting element is placeable against a wall of the vein at the cutting site.11 . The catheter according to any preceding claim, wherein the cutting element is formed on at least one of an end surface of the end portion and on a side surface of the end portion.

12. The catheter according to any preceding claim, wherein the distal portion has a bevel shaped portion with respect to a central longitudinal axis of the elongate body.

13. The catheter according to any preceding claim, wherein the cutting element is located on or in the bevel shaped portion.

14. The catheter according to any preceding claim, wherein the cutting element is diamond-shaped, or oval-shaped, and surrounds the lumen.

15. A catheter for percutaneously creating an arteriovenous fistula by itself in concomitant vessels, the concomitant vessels being a vein and an artery, the catheter comprising: an elongate body dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion and a distal portion, the distal portion having an end portion; a lumen extending through the elongate body for accommodating a guidewire; the catheter further comprising: an activatable cutting element,wherein the activatable cutting element is configured to be deployable and retractable through the lumen, wherein the activatable cutting element is configured to deliver energy to create the fistula, wherein the activatable cutting element is arranged to be initially activated when the cutting element is located in the vein and before at least a portion of the cutting element is located in the artery.

16. The catheter according to claim 15, wherein the cutting element comprises an umbrella having a plurality of spokes.

17. The catheter according to claim 16 or claim 17, wherein the catheter further comprising a deployment element for deploying the umbrella.

18. The catheter according to claim 18, wherein the deployment element comprises a rigid push rod.

19. The catheter according to any of claims 16 to 18, wherein the umbrella is configured to transition between a folded state, in which state the umbrella may fit within the lumen, and at least one of an expanded state and a partially expanded state.

20. The catheter according to any of claims 16 to 19, wherein the activatable cutting element is configured to be disabled while the umbrella is within the lumen.21 . The catheter according to any of claims 16 to 20, wherein the activatable cutting element comprises one or more cutting electrodes.

22. The catheter according to claim 21 , wherein the one or more spokes constitute the one or more cutting electrodes.

23. The catheter according to claim 21 or claim 22, wherein the one or more spokes are flexible.

24. The catheter according to any of claims 22 to 23, wherein the one or more spokes comprise nitinol wire.

25. The catheter according to any of claims 21 to 24, wherein the one or more cutting electrodes is arranged as at least one of: one or more spoke electrodes,a spiral electrode; and / or one or more ring electrodes.

26. The catheter according to any of claims 21 to 25, wherein the one or more electrodes is arranged on an distal-facing surface of the umbrella when the umbrella is in the expanded or partially expanded state.

27. The catheter according to any of claims 21 to 26, wherein the one or more spokes is arranged so that each of the one or more electrodes sits within a respective groove of the umbrella material.

28. The catheter according to any of claims 21 to 27, wherein the activatable cutting element is configured such that the one or more electrodes can only be activated when the umbrella is in the expanded or partially expanded state..

29. The catheter according to any of claims 16 to 28, wherein a state of deployment of the umbrella is manually or automatically adjustable.

30. The catheter according to any of claims 15 to 29, wherein the at least one of the distal portion and the end portion comprises one or more visualisation aids, wherein the visualisation aids are configured to allow the catheter to be visualized by a detection device, for example, an ultrasound device.

31. The catheter according to claim 30, wherein the one or more visualisation aids comprises one or more cutouts.

32. The catheter according to claim 30 or 31 , wherein the catheter comprises one or more reinforcement elements for reinforcing the catheter arranged to a least partially compensate for material absent in the one or more cutouts.

33. The catheter according to any of claims 30 to 32, wherein the one or more visualisation aids and / or the one or more reinforcement elements are arranged circumferentially around the catheter.

34. The catheter according to claim 32 or 33, wherein the one or more reinforcement elements comprise one or more reinforcement splines, respectively.

35. The catheter according to claim 34, wherein the one or more reinforcements splines comprises metal or wherein the catheter comprises pebax and the reinforcement splines comprise a higher durometer pebax ®.

36. The catheter according to any of claims 32 to 35, wherein the one or more reinforcement elements comprises a metal braid, wherein the metal braid is disposed at the one or more locations of the one or more cutouts.

37. The catheter according to any preceding claim, wherein the activatable cutting element is configured to use at least one of radiofrequency ablation, thermal, laser, microwave and cryogenic energy.

38. A device for creating an arteriovenous fistula and / or guidewire placement in concomitant vessels, the device comprising the catheter of any of claims 1 to 37.

39. The device according to claim 38, the device further comprising: a handle, the handle comprising: a steering element for steering the distal portion of the catheter in a direction, for example, towards the cutting site.

40. The device according to claim 38 or 39, wherein the steering element comprises at least one of mechanical and pneumatic actuators.41 . The device according to any of claims 38 to 40, the device further comprising: a sheath for accommodating the catheter, wherein the sheath comprises a lumen through which the catheter is advanceable.

42. The device according to any of claims 38 to 41 , the device further comprising a guidewire.

43. The device according to any of claims 38 to 42, wherein the catheter is a single catheter.

44. A system for creating an arteriovenous fistula and / or guidewire placement in concomitant vessels, the system comprising: the device according to any of claims 38 to 43.

45. The system according to claim 44, the system further comprising: a needle element arranged to puncture through the vein and artery to allow the guidewire access to the artery.

46. The system according to claim 45, wherein the needle element is arranged to gain an initial access through the vein and artery in an access region in a single operation.

47. The system according to any of claims 44 to 46, the system further comprising: a non-invasive detection system for detecting the location of the catheter, in use.

48. A method for percutaneously creating an arteriovenous fistula in concomitant vessels, the concomitant vessels being a vein and an artery, the method comprising: inserting a guidewire percutaneously such that the guidewire extends from a vein into an artery; inserting a catheter over the guidewire and into the vein, the catheter comprising: an elongate body dimensioned so as to be insertable into the vein, the elongate body comprising a proximal portion and a distal portion, the distal portion having an end portion; a lumen extending through the elongate body for accommodating the guidewire; an activatable cutting element located at or in the vicinity of the end portion; the method further comprising: advancing the catheter along the guidewire until the end portion is adjacent a point where the guidewire exits the vein and enters into the artery; and activating the activatable cutting element and advancing the activatable cutting element along the guidewire to form a fistula between the vein and the artery.

49. The method of claim 48, wherein the step of inserting a guidewire includes inserting a needle element through the skin, into the vein and through the vein into an artery; inserting the guidewire through the needle; and withdrawing the needle proximally over the guidewire.

50. The method of claim 48, wherein, prior to the step of activating the activatable cutting element, the method further comprises deploying a furled umbrella that comprises the activatable cutting element from the lumen, and transitioning the umbrella from a furled state to an expanded or partially expanded state.51 . The method of claim 48, wherein the catheter is a catheter according to any of claims 1-37.

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