CATHETER DEVICE WITH BIASING RAIL AND METHOD FOR FORMING A STOMUS - Patent application

Abstract

A device for forming a fistula includes a catheter including a catheter body, an electrode, one or more magnetic arrays, and a plurality of biasing rails. The one or more magnetic arrays are longitudinally disposed along the catheter body. The plurality of biasing rails extend along the length of the catheter body and are configured to arc radially away from the catheter body between a proximal point positioned proximal to a first end of at least one magnetic array and a distal point positioned distal to a second end of at least one magnetic array. The plurality of biasing rails bias the active site and the one or more magnetic arrays against the vessel wall. The plurality of biasing rails are connected by a connecting rail extending laterally between the plurality of biasing rails.

Description

[Technical field]

[0001]

[0001] The present disclosure relates to devices and methods for forming a fistula, and more particularly to devices and methods that use integrated biasing rails to bias the device into contact with a vessel for fistula formation. [Background technology]

[0002] A fistula is generally a passageway formed between two internal organs. Forming a fistula between two blood vessels can have one or more beneficial functions. For example, forming a fistula between an artery and a vein can provide access to the vasculature for hemodialysis patients. Specifically, forming a fistula between an artery and a vein allows blood to flow quickly between the vessels while bypassing the capillaries. In other cases, a fistula can be formed between two veins to form a veno-venous fistula. Generally, fistula formation requires surgical dissection of the target vein and further requires transecting and moving the vein to the artery for surgical anastomosis. Therefore, it may be beneficial to find a minimally invasive and reliable device and method for forming a fistula between two blood vessels. Summary of the Invention [Problem to be solved by the invention]

[0003]

[0003] One of the most challenging aspects of forming a fistula between blood vessels, although other body vessels are contemplated and possible, is properly aligning and joining the catheter in the adjacent blood vessel prior to fistula formation. Thus, a need exists for alternative devices, methods, and catheters for fistula formation that ensure alignment and joining of the catheter. The embodiments of the present disclosure are directed to improving upon the above limitations by providing a biasing rail that biases the catheter into proper alignment. [Means for solving the problem]

[0004] In one embodiment, an apparatus for forming a fistula between two blood vessels includes a first catheter including a first catheter body, an electrode, one or more magnet arrays, and a first plurality of biasing rails. The electrode is configured to protrude from an active site of the first catheter and to define an active side of the first catheter. The one or more magnet arrays are disposed longitudinally along the first catheter body. The first plurality of biasing rails extend longitudinally along a length of the first catheter body and are configured to longitudinally straddle at least one of the one or more magnet arrays and radially arc away from the first catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnet arrays and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays. A first plurality of biasing rails extend from the non-active side of the first catheter body such that the first plurality of biasing rails are configured to bias the effect site and the one or more magnetic arrays against the first vessel wall, and the first plurality of biasing rails are connected by a connecting rail extending laterally between the first plurality of biasing rails at a point between the proximal point and the distal point.

[0005] In another embodiment, a method of forming a fistula between a first blood vessel and a second blood vessel includes advancing a first catheter into the first blood vessel. The first catheter includes a first catheter body, an electrode, one or more magnet arrays, and a first plurality of biasing rails. The electrodes are configured to protrude from an active site of the first catheter and define an active side of the first catheter. The one or more magnet arrays are disposed longitudinally along the first catheter body. The first plurality of biasing rails extend longitudinally along a length of the first catheter body and are configured to longitudinally straddle at least one of the one or more magnet arrays and radially arc away from the first catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnet arrays and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays. The first plurality of biasing rails extend from the non-active side of the first catheter body such that the first plurality of biasing rails are configured to bias the action site and the one or more magnet arrays against the first vessel wall. The method further includes cauterizing tissue with the electrodes to form a fistula.

[0006] In another embodiment, an apparatus for forming a fistula between two blood vessels includes a first catheter. The first catheter includes a catheter body, an electrode, one or more magnet arrays, and a plurality of biasing rails. The electrode is configured to protrude from an action site of the first catheter and to define an active side of the first catheter. The one or more magnet arrays are disposed longitudinally along the catheter body. The plurality of biasing rails extend longitudinally along the length of the catheter body. The plurality of biasing rails are configured to span at least one of the one or more magnet arrays longitudinally and to arc radially away from the catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnet arrays and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays. The plurality of biasing rails extend from the inactive side of the catheter body, whereby the plurality of biasing rails are configured to bias the action site and the one or more magnet arrays against the first blood vessel wall. The biasing rails are connected by a connecting rail extending laterally between the biasing rails at a point between the proximal and distal points, the biasing rails include a proximal portion extending through a lumen of the catheter body, the proximal portion can be advanced within the lumen to transition the biasing rails to an extended configuration, the biasing rails arching radially away from the catheter body, and the proximal portion can be retracted within the lumen to transition the biasing rails to a low-profile configuration, a maximum radial deflection distance of the biasing rails being less than a maximum radial deflection distance of the biasing rails in the extended configuration.

[0007]

[0007] These and additional features provided by the embodiments described herein will be more fully understood when the following detailed description is considered in conjunction with the drawings.

[0008] The embodiments illustrated in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, in which like structure is indicated with like reference numerals and in which: [Brief description of the drawings]

[0008] [Figure 1A]

[0009] FIG. 1 is a schematic side view of a catheter according to one or more embodiments shown and described herein. [Figure 1B]

[0010] FIG. 1B is a schematic top view of the catheter of FIG. 1A according to one or more embodiments shown and described herein. [Figure 1C]

[0011] 1B is a schematic side view illustrating a sheath advanced distally through the catheter of FIG. 1A according to one or more embodiments shown and described herein. [Figure 2A]

[0012] FIG. 2A is a schematic cross-sectional view illustrating a catheter with multiple biasing rails in a low-profile delivery configuration according to one or more embodiments shown and described herein. [Figure 2B]

[0013] FIG. 2B is a schematic cross-sectional view illustrating the catheter of FIG. 2A with multiple biasing rails in an extended configuration according to one or more embodiments shown and described herein. [Figure 3A]

[0014] FIG. 3A is a schematic diagram illustrating two catheter devices according to one or more embodiments shown and described herein. [Figure 3B]

[0015] FIG. 3B is a schematic diagram illustrating two catheter devices according to one or more embodiments shown and described herein. [Figure 4]

[0016] FIG. 2 is a schematic side view of another catheter according to one or more embodiments shown and described herein. [Diagram 5]

[0017] FIG. 2 is a schematic side view of another catheter according to one or more embodiments shown and described herein. [Figure 6]

[0018] FIG. 2 is a schematic side view of another catheter according to one or more embodiments shown and described herein. [Figure 7]

[0019] FIG. 2 is a schematic side view of another catheter according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]

[0020] The embodiments described herein are directed to devices and methods for forming fistulas. In some embodiments, the devices and methods can be used to form fistulas between two blood vessels. More specifically, a catheter can be placed in each of two adjacent blood vessels to form a fistula between the two adjacent blood vessels using the catheter.

[0010]

[0021] The fistula forming element can be attached to a catheter, which can then be used to form a fistula between the vessels. However, catheter flexibility, vessel spacing, vessel wall thickness, and / or vessel tortuous structure can make it difficult to provide sufficient intervascular coaptation and / or alignment for fistula formation. The embodiments described herein address one or more of the limitations discussed above. In particular, the devices and methods for forming fistulas described herein can include a catheter having a catheter body, an electrode, one or more magnet arrays, and a plurality of biasing rails. The electrode can be configured to protrude from an active site of the catheter and define an active side of the catheter. The plurality of biasing rails extend longitudinally along the length of the catheter body and are configured to span at least one of the one or more magnet arrays longitudinally, radially arching away from the catheter body between a proximal point positioned proximal to a first end of at least one of the one or more magnet arrays and a distal point positioned distal to a second end of at least one of the one or more magnet arrays. The biasing rails can be connected by a connecting rail extending laterally between the biasing rails at a point between the proximal and distal points. The biasing rails extend from the non-active side of the catheter body, whereby the biasing rails are configured to bias the working site and / or the one or more magnet arrays against the vessel wall. Thus, the biasing rails facilitate positioning of the one or more magnet arrays against the vessel wall to enable better magnetic attraction between the one or more magnet arrays of the catheter and the one or more magnet arrays attached to a second catheter, which can be positioned in a second vessel adjacent to the vessel. Thus, the biasing rails, in conjunction with the one or more magnet arrays, can align and bring the first and second catheters into close proximity in the adjacent vessels, thereby enabling more reliable fistula formation between the first and second vessels. Various embodiments will now be discussed in more detail below with reference to the figures.

[0011]

[0022] Referring now to FIG. 1A, a catheter 100 (e.g., a first catheter) of a device for forming a fistula is depicted. As described in more detail herein, the device may further include a second catheter 400 (FIG. 3A). Although the structure of the first catheter 100 will be discussed in detail, it should be understood that the structure of the second catheter 400 (FIG. 3A) may be similar to the first catheter 100 except as described. The catheter 100 generally includes a catheter body 102, which may include a distal tip 140 specifically configured to assist the catheter 100 in advancing through a blood vessel. For example, the distal tip 140 may be sharp and / or atraumatic for advancing through a blood vessel. The catheter body 102 may have any desired cross-sectional shape and any suitable diameter for intravascular use. The catheter 100 may further include one or more lumens or other passages extending at least partially along or through the catheter body 102. For example, one or more lumens can extend at least partially longitudinally through the catheter body 102 in the direction of the x-axis of the coordinate axes of FIG. 1A.

[0012]

[0023] The catheter 100 may further include an action site 135 disposed along the catheter body 102. The action site 135, as described herein, refers to a portion of the catheter 100 disposed along the catheter body 102 that is configured to modify (e.g., cut, cauterize, etc.) a blood vessel. In particular, in an embodiment of the present disclosure, the catheter 100 may include an action site 135 configured to form one or more fistulas between a first blood vessel 300 (FIG. 3A) and a second blood vessel 302 (FIG. 3A). In an embodiment, the action site 135 may be disposed along the catheter body 102 at a location proximal to the distal tip 140 (e.g., in the −x direction of the coordinate axes of FIG. 1A) and may define an active side 134. The action site 135 may include one or more openings at the active side 134 of the action site 135 that allow one or more instruments to pass into and / or out of the catheter body 102 to modify the vessel. For example, the active side 134 of the working site 135 is the portion of the working site 135 that abuts or faces the area of ​​the vessel where modification is to be made. For example, the electrodes 108 can protrude from the active side 134 of the working site 135 and extend radially away from the longitudinal centerline of the catheter 100 to contact the wall of the blood vessel 300 (see, e.g., FIG. 3B).

[0013]

[0024] The electrode 108 may include an exposed ablation surface that may be activated to cauterize tissue, and a lead wire or other conductor attached to the ablation surface. In particular, when activated, the electrode 108 may supply current to and / or carry current from tissue and fluids via the ablation surface to facilitate cauterization or vaporization of tissue to form a fistula. In some embodiments, the electrode 108 may be a spring wire or leaf spring electrode and may be movable between a retracted configuration in which the electrode 108 is retained within the catheter 100 and a protruding configuration in which the electrode 108 protrudes from the surface of the catheter body 102. The electrode 108 may or may not be naturally biased to protrude from the catheter body 102. When the electrode 108 is naturally biased to protrude from the catheter body 102, a structure such as a sleeve 160 may be used to hold or maintain the electrode 108 in the retracted configuration until deployment (in other words, deployment) is desired. In some embodiments, the catheter body 102 may include one or more insulating materials (not shown) that may shield or otherwise protect the catheter 100 and its components from heat generated by the electrodes 108 during use.

[0014]

[0025] 1A, the catheter 100 includes an inactive side 103 or region located opposite the active side 134 of the action site 135. For example, the inactive side 103 refers to the side of the catheter 100 that does not include the cutting and / or cauterizing means. The inactive side 103 of the catheter 100 extends across the catheter body 102 and the action site 135. In other words, both the catheter body 102 and the action site 135 can define an inactive side 103. The inactive side 103 of the catheter body 102 and the action site 135 is diametrically opposed from the active side 134 of the action site 135. Thus, the inactive side 103 of the catheter body 102 and the action site 135 is located opposite the electrode 108. In other words, the non-active side 103 of the catheter body 102 and the working site 135 do not abut or face the modification made in the blood vessel 300 (FIG. 3A) through the active side 134 of the working site 135. Instead, the non-active side 103 of the catheter body 102 can be spaced apart from the modification made in the blood vessel 300 (FIG. 3A) by the electrode 108 by at least a diameter or height of a portion of the catheter body 102 (e.g., in the direction of the z-axis of the coordinate axes of FIG. 1A).

[0015]

[0026] With further reference to FIG. 1A, the catheter 100 can include one or more magnet arrays disposed longitudinally along the catheter body 102. For example, the catheter 100 can include a first magnet array 104 that extends longitudinally along the catheter body 102 and is disposed proximal to the site of action 135 (e.g., in the −x direction of the coordinate axes of FIG. 1A). The catheter 100 can include a second magnet array 106 that extends longitudinally along the catheter body 102 and is disposed distal to the site of action 135 (e.g., in the +x direction of the coordinate axes of FIG. 1A). In some embodiments, the second magnet array 106 can be disposed longitudinally between the site of action 135 and a distal tip 140 of the catheter body 102 (e.g., in the direction of the x axis of the coordinate axes of FIG. 1A). In an embodiment, the catheter 100 may include a third magnet array 150 disposed within the working site 135 behind (in other words, on the back side of) the active side 134 of the working site 135. More specifically, the third magnet array 150 may be disposed along and / or within the inactive side 103 of the working site 135. In an embodiment, the catheter 100 may include the first magnet array 104, the second magnet array 106, and the third magnet array 150 individually or in any combination. Although the phrase "magnetic array" is used herein, it should be understood that each of the magnet arrays 104, 106, and 150 may also be configured as a single magnet along the catheter body 102 and / or working site 135.

[0016]

[0027] The magnet arrays 104, 106, and 150 described herein may be permanent magnets including one or more hard magnetic materials, such as, but not limited to, alloys of rare earth elements (e.g., samarium-cobalt magnets, or neodymium magnets such as N52 magnets), or alnico. In some variations, the magnet arrays 104, 106, and 150 may include anisotropic magnets, and in other variations, the magnet arrays 104, 106, and 150 may include isotropic magnets. In some variations, the magnet arrays 104, 106, and 150 may be formed from compressed powders. In some variations, a portion of the magnet arrays 104, 106, and 150 (e.g., a transparent backing) may include one or more soft magnetic materials, such as, but not limited to, iron, cobalt, nickel, or ferrite. It should be understood that in a device comprising two catheters, the first catheter 100 or the second catheter 400 (FIGS. 3A and 3B) can include ferromagnetic elements (i.e., elements that are attracted to but do not generate a permanent magnetic field). For example, in some variations, the first catheter 100 can include only one or more ferromagnetic elements, and the second catheter 400 (FIGS. 3A and 3B) can include one or more permanent magnets. In other variations, the second catheter 400 (FIGS. 3A and 3B) can include only one or more ferromagnetic elements, and the first catheter 100 can include one or more permanent magnets. However, in other variations, one or both of the first catheter 100 and the second catheter 400 (FIGS. 3A and 3B) can include any suitable combination of ferromagnetic magnets, permanent magnets, and / or other suitable types of magnets.

[0017]

[0028] In general, the dimensions of the magnetic arrays 104, 106, and 150 described herein can be selected based on the size of the catheter 100 that will hold the magnetic arrays 104, 106, and 150, which in turn can be selected based on the anatomical dimensions of a selected vessel through which the catheter 100 can be advanced. For example, when advancing the catheter 100 through a vessel 300 (FIGS. 3A and 3B) having an inner diameter of about 3 mm, it may be desirable to configure any of the magnetic arrays 104, 106, and 150 to have a cross-sectional area of ​​less than about 3 mm at their widest points to reduce the risk of injury to the vessel wall during advancement and manipulation of the catheter 100. It should be understood that each magnetic array 104, 106, and 150 can have any suitable length (e.g., about 5 mm, about 10 mm, about 15 mm, about 20 mm, etc.), although in some cases, a longer magnetic array may limit the flexibility of the catheter 100 for maneuvering through a vessel. In some variations, the magnet arrays 104, 106, and 150 may include multiple rectangular magnets. In other embodiments, each magnet of the magnet arrays 104, 106, and 150 may have any suitable shape for placement inside or outside the catheter. The magnets may be cylindrical, semi-cylindrical, tubular, box-shaped, etc.

[0018]

[0029] In embodiments, the outer surfaces of the magnet arrays 104, 106, and 150 can be flush or aligned with the outer surface of the catheter body 102. In other embodiments, the magnets 104, 106, and 150 can be positioned radially within the catheter body 102 away from the outer surface of the catheter body 102. In other embodiments, the outer surfaces of the magnet arrays 104, 106, and 150 can extend a radial distance beyond the outer surface of the catheter body 102.

[0019]

[0030] Each magnetic array 104, 106, 150 may be secured in or on the catheter 100 by any suitable method. For example, in some variations, one or more magnetic arrays 104, 106, and 150 may be embedded in, attached to, or friction-fitted to the catheter 100.

[0020]

[0031] With further reference to FIG. 1A, the catheter 100 may further include one or more biasing rails. In an embodiment, the catheter 100 may include a plurality of biasing rails 120, the plurality of biasing rails 120 including a first biasing rail 122 and a second biasing rail 124. Although the plurality of biasing rails 120 is discussed as a pair of biasing rails 122, 124, it should be understood that the plurality of biasing rails 120 may include any number of biasing rails. The plurality of biasing rails 120 may extend longitudinally along the length of the catheter body 102 (e.g., in the direction of the x-axis of the coordinate axes of FIG. 1A). The plurality of biasing rails 120 may arc radially away from the catheter body 102 between a proximal point 130 and a distal point 132 of the catheter body 102. The proximal point 130 can be positioned proximal to a first end of at least one of the magnet arrays 104, 106, 150 (e.g., in the −x direction of the coordinate axes of FIG. 1A ), and the distal point 132 can be positioned distal to a second end of at least one of the magnet arrays 104, 106, 150 (e.g., in the +x direction of the coordinate axes of FIG. 1A ). Thus, the multiple biasing rails 120 can be configured to longitudinally straddle at least one of the magnet arrays 104, 105, 150. In other words, at least one of the first magnet array 104, the second magnet array 106, and the third magnet array 150 can be disposed longitudinally between the proximal point 130 and the distal point 132 (e.g., in the x direction of the coordinate axes of FIG. 1A ). In an embodiment, as discussed in further detail in connection with Figures 3A and 3B, multiple biasing rails 120 can be positioned to bias one or more of the magnetic arrays 104, 106, 150 against the vessel wall.

[0021]

[0032] In an embodiment, the plurality of biasing rails 120 may extend radially from the inactive side 103 of the catheter 100. In other words, the proximal point 130 and the distal point 132 may be disposed along the inactive side 103 of the catheter body 102. More specifically, in an embodiment, the lateral center point 137 (FIG. 1B) of the plurality of biasing rails 120 may be located diametrically opposite the active side 134 of the action site 135. The lateral center point 137 may be a point equidistant from the lateral (e.g., in the direction of the y-axis of the coordinate system of FIG. 1A) outer edges of the biasing rails (i.e., the first biasing rail 122 and the second biasing rail 124) of the plurality of biasing rails 120. In an embodiment, the action site 135 may be disposed longitudinally (e.g., in the direction of the x-axis of the coordinate system of FIG. 1A) between the proximal point 130 and the distal point 132. In an embodiment, as discussed in more detail with respect to Figures 3A and 3B, the multiple biasing rails 120 can be configured to bias the action portion 135, and more specifically, the active side 134 of the action portion 135, against the blood vessel wall.

[0022]

[0033] In an embodiment, the plurality of biasing rails 120 may be proximally skewed (e.g., skewed in the −x direction of the coordinate system of FIG. 1A). In other words, a first distance L1 (in the x direction of the coordinate system of FIG. 1A) between a proximal point 130 and an apex 131 of the plurality of biasing rails 120 may be less than a second distance L2 (in the x direction of the coordinate system of FIG. 1A) between a distal point 132 and an apex 131 of the plurality of biasing rails 120. The apex 131 of the plurality of biasing rails 120 may be a point along a longitudinal direction of the plurality of biasing rails 120 (e.g., in the x direction of the coordinate system of FIG. 1A) that exhibits a maximum height MH or maximum radial deflection from the catheter body 102 when the plurality of biasing rails is in an extended (or elongated) configuration. Thus, in an embodiment, the point of maximum height MH along the plurality of biasing rails 120 is closer to the proximal point 130 (e.g., along the x-axis of the coordinate axes of FIG. 1A ) than to the distal point 132. In such an embodiment, the plurality of biasing rails 120 are specifically configured to bias the first magnet array 104 and the action site 135 against the wall of the blood vessel 300 ( FIG. 3A ).

[0023]

[0034] Referring again to FIG. 1A, which depicts the non-active side 103 of the catheter 100, in conjunction with FIG. 1B, the multiple biasing rails 120 may include one or more connecting rails 126, 126', 126". The one or more connecting rails 126, 126', 126" may extend laterally between a first biasing rail 122 and a second biasing rail 124 of the multiple biasing rails 120 and may connect the first biasing rail 122 and the second biasing rail 124. One or more connecting rails 126, 126', 126" can extend between the biasing rails 122 and 124 at a point between the longitudinal direction of the proximal point 130 and the distal point 132 (e.g., in the direction of the x-axis of the coordinate axes of Figures 1A and 1B). The one or more connecting rails 126, 126', 126" can prevent the first biasing rail 122 and the second biasing rail 124 from rotating away from or toward each other (i.e., rotating in opposite directions around the catheter body 102) when contacting the wall of the blood vessel 300 (Figure 3A).

[0024]

[0035] As discussed above, the plurality of biasing rails 120 can be radially arcuate away from the catheter body 102 of the catheter 100 between the proximal point 130 and the distal point 132. In some embodiments, the biasing rails 122, 124 of the plurality of biasing rails 120 can be fixedly attached to the catheter body 102 at the proximal point 130 and the distal point 132. In such embodiments, the biasing rails 122, 124 can be fixed to the catheter body 102 at the proximal point 130 and the distal point 132 by an adhesive, such as a suitable polymer or glue, laser welding, a heat shrink plastic wrap, or the like. In embodiments, the proximal point 130 can be contained within a cap 142 coupled to the catheter body 102, and the distal point 132 can be contained within a cap 144 coupled to the catheter body 102. The caps 142, 144 can be metal, plastic, composite, or the like, and can shield the proximal point 130 and the distal point 132 from the outside environment.

[0025]

[0036] In embodiments, the biasing rails 122, 124 of the plurality of biasing rails 120 can have a circular cross-section. In embodiments, the biasing rails 122, 124 of the plurality of biasing rails 120 can be flat ribbons having a substantially rectangular cross-section. In some embodiments, the biasing rails 122, 124 can transition between a first section of the biasing rails 122, 124 having a circular cross-section and a second section of the biasing rails having a substantially rectangular cross-section. For example, a proximal end of the biasing rails 122, 124 adjacent the proximal point 130 can have a circular cross-section, a distal end of the biasing rails 122, 124 adjacent the distal point 132 can have a circular cross-section, and a section of the biasing rails 122, 124 between the proximal and distal ends can have a rectangular cross-section. In embodiments, the biasing rails 122, 124 of the plurality of biasing rails 120 can be made from a metal, a plastic, a polymer, a metal coated with a plastic, a composite of any of the above materials, or the like. For example, the biasing rails 122, 124 can be nitinol, stainless steel, polyethylene terephthalate, polyetheretherketone, polytetrafluoroethylene, polyimide, etc. The biasing rails 122, 124 can be a material that exhibits shape memory and returns to a set or desired shape. In an embodiment, the connecting rail(s) 126, 126', 126" can be a flat ribbon or a circular ribbon. The connecting rail(s) 126, 126', 126" can be a metal, plastic, polymer, metal coated with plastic, a composite of any of the above materials, etc. The connecting rail(s) 12, 126', 126" can be coupled to the biasing rails 122, 124 via any coupling technique, such as, for example, adhesive, soldering, or welding.

[0026]

[0037] In some embodiments, the biasing rails 120 can be extended from a low-profile (or contoured) configuration to an extended configuration as depicted in FIG. 1A. In the low-profile configuration, the biasing rails 120 can be disposed in a non-contacting state in which the biasing rails 120 do not apply a biasing force to the walls of the blood vessel 300 (FIG. 3A) to bias the catheter 100 laterally within the blood vessel 300 (FIG. 3A). In the low-profile configuration, the biasing rails 120 can be maintained substantially flush with or within the catheter body 102 of the catheter 100. Thus, the catheter 100 can be advanced to a desired location within the blood vessel 300 (FIG. 3A) without the biasing rails 120 extending radially from the catheter body 102 and without applying a biasing force to the walls of the blood vessel 300 (FIG. 3A) to bias the catheter 100 laterally within the blood vessel 300 (FIG. 3A). In the extended configuration, at least a portion of the biasing rails 120 can extend radially outward from an outer surface of the catheter body 102 into contact where at least a portion of the biasing rails 120 apply a biasing force to a wall of the blood vessel 300 (FIG. 3A). Thus, the maximum distance that the biasing rails 120 radially deflect from the outer surface of the catheter body 102 when in the extended configuration can be greater than the maximum distance that the biasing rails 120 radially deflect from the outer surface of the catheter body 102 when in the low-profile configuration.

[0027]

[0038] In embodiments, the biasing rails 120 described herein can be biased toward the extended configuration. That is, the biasing rails 120 can be configured to self-expand from a low-profile configuration to an extended configuration. In other words, the biasing rails 120 can be naturally at rest in an extended configuration in which the biasing rails 122, 124 of the biasing rails 120 extend radially a predetermined distance away from the outer surface of the catheter body 102. In such embodiments, a force may be required to hold the biasing rails 120 in the low-profile configuration. For example, with reference to FIGS. 1A-1C, the sheath 160 can be advanced distally (e.g., in the +x direction of the coordinate axis of FIGS. 1A-1C) to maintain the biasing rails 120 in the low-profile configuration. The sheath 160 can include a lumen having a larger diameter than the catheter body 102 and one or more magnetic arrays 104, 106, 150 of the catheter 100, as depicted in FIG. 1C, thereby allowing the sheath 160 to be advanced distally over the catheter body 102 and one or more magnetic arrays 104, 106, 150. Thus, with the sheath 160 advanced distally over the catheter body 102 and one or more magnetic arrays 104, 106, 150, the multiple biasing rails 120 can be compressed against the catheter body 102 by the sheath 160. In other words, the multiple biasing rails 120 can be compressed and maintained in a low-profile configuration within the space between the catheter body 102 and the sheath 160. For example, the catheter 100 within the sheath 160 can be advanced within the blood vessel 300 (FIG. 3A) to a desired location to form a fistula, at which point the sheath 160 can be retracted proximally (e.g., in the −x direction of the coordinate axes of FIGS. 1A-1C), thereby exposing the plurality of biased rails 120. When the sheath 160 is no longer applying a force to the plurality of biased rails 120 to maintain them in the low-profile configuration, the natural bias of the plurality of biased rails 120 can naturally expand into the extended configuration shown in FIG. 1A.

[0028]

[0039] In some embodiments, the biasing rails 120 can be made from a shape memory alloy, such as copper-aluminum-nickel and nickel-titanium, that changes shape in response to environmental factors such as temperature. For example, the active state shape of the biasing rails 120 can be the extended configuration depicted in FIG. 1A. The transition temperature of the shape memory alloy can be above standard room temperature. In some embodiments, the transition temperature of the shape memory alloy can be about body temperature. Thus, outside the patient's body at standard room temperature, the biasing rails 120 can be transformed into a low profile configuration in which the biasing rails 120 are in a non-contact state and do not extend radially away from the outer surface of the catheter body 102 to apply a biasing force to the wall of the blood vessel 300 (FIG. 3A). As the temperature of the biasing rails 120 increases, the biasing rails 120 may naturally transition from a low-profile configuration to an extended configuration where the biasing rails 120 come into contact and extend radially away from the outer surface of the catheter body 102 and apply a biasing force to the wall of the blood vessel 300 (FIG. 3A) to bias the catheter 100 laterally within the blood vessel 300 (FIG. 3A). In embodiments, the biasing rails 120 may transition from a low-profile configuration to an extended configuration at temperatures above 30° C., above 32° C., above 35° C., and similar temperatures between standard room temperature of 20° C. and body temperature of 37° C.

[0029]

[0040] In some embodiments, the multiple biasing rails 120 described herein can be configured such that the multiple biasing rails 120 are movable within the catheter body 102 of the catheter 100. For example, referring to Figures 2A and 2B, which depict a cross-sectional view of the interior of the catheter 100, the multiple biasing rails 120 can extend through a lumen 802 of the catheter body 102. Although the multiple biasing rails 120 are depicted as extending through the lumen 802 and the electrodes 108 are depicted as extending through a lumen 804 of the catheter body 102, it should be understood that in some embodiments, the multiple biasing rails 120 and the electrodes 108 can also extend through a common lumen, such as the lumen 804. Physical interference between the movement of the multiple biasing rails 120 and the electrodes 108 within the catheter body 102 can be reduced when the multiple biasing rails 120 extend through the lumen 802 and the electrodes 108 extend through the lumen 804. In an embodiment, the multiple biasing rails 120 can extend through an opening 808 in the catheter body 102 at a proximal point 130. That is, the proximal point 130 can define an opening 808 that enters a lumen 802 in the catheter body 102. The multiple biasing rails 120 can extend proximally (e.g., in the −x direction of the coordinate axes of FIGS. 2A and 2B ) through the interior of the catheter body 102, through the lumen 802. Thus, the multiple biasing rails 120 can be movable within the lumen 802 of the catheter body 102. In a low-profile configuration, as depicted in FIG. 2A , a proximal portion 806 of the multiple biasing rails 120 can be housed within the lumen 802. The multiple biasing rails 120 can move within the lumen 802, with the proximal portion 806 of the multiple biasing rails 120 extending outward from the opening 808. When the proximal portion 806 expands outward from the opening 808, the multiple biasing rails 120 can extend radially away from the catheter body 102 between the proximal point 130 and the distal point 132 and can move to an extended configuration as depicted in FIG. 2B.

[0030]

[0041] In an embodiment, the plurality of biasing rails 120 can be biased into an extended configuration. In other words, the proximal portion 806 of the plurality of biasing rails can be biased to expand outwardly from the opening 808. The sheath 160 (FIGS. 1A-1C) can maintain the plurality of biasing rails 120 in a low profile configuration. For example, the sheath 160 (FIGS. 1A-1C) can be advanced distally (e.g., in the +x direction of the coordinate axes of FIGS. 2A and 2B) over the catheter 100. The sheath 160 (FIGS. 1A-1C) can apply an inward force to the plurality of biasing rails 120 to compress the plurality of biasing rails 120, causing the proximal portion 806 of the plurality of biasing rails 120 to slide proximally (e.g., in the −x direction of the coordinate axes of FIGS. 2A and 2B) within the lumen 802. The sheath 160 (FIGS. 1A-1C) can further prevent the proximal portion 806 from extending distally out of the opening 808. Thus, the proximal portion 806 can be maintained within the lumen 802 and the plurality of biased rails 120 can be maintained in a low profile configuration. Further, removing the sheath 160 (FIGS. 1A-1C) proximally (e.g., in the −x direction of the coordinate axes of FIGS. 2A and 2B) can allow the natural bias of the proximal portion 806 to extend the proximal portion 806 of the plurality of biased rails 120 out of the opening 808. Thus, the plurality of biased rails 120 can assume the extended configuration depicted in FIG. 2B.

[0031]

[0042] It should be appreciated that in embodiments, the biasing rails 120 may be secured to the catheter body 102 at a distal point 132 and may extend through the catheter body 102 at a proximal point 130 into the lumen 802. In other embodiments, the biasing rails 120 may similarly be secured to the catheter body 102 at a proximal point 130 and may extend through the catheter body 102 at a distal point 132 into the lumen 802. The distal point 132 may thus define an access opening into the lumen 802. In such embodiments, the biasing rails 120 may operate as described above since the biasing rails 120 may transition between a low profile configuration and an extended configuration in response to expansion or squeezing of the biasing rails 120 through an opening at the distal point 132 in the catheter body 102. In some embodiments, the biasing rails 120 may extend through the catheter body 102 into the lumen 802 at both the proximal point 130 and the distal point 132. In such embodiments, both the proximal portion 806 and the corresponding distal portion of the plurality of biasing rails 120 may be movable within the lumen 802 .

[0032]

[0043] In the embodiments discussed above with reference to Figures 1-2B, the natural bias of the biasing rails 120 may eliminate the need for a user-actuated control to hold the biasing rails 120 in a low-profile configuration for delivery through the vasculature in a first state and to allow the biasing rails 120 to enter an extended configuration for applying a biasing force to the wall of the blood vessel 300 (Figure 3A) in a second state. The biasing rails 120 may be movable between the low-profile configuration and the extended configuration, but this movement may occur as a natural result of a combination of the biasing of the biasing rails 120 and an external force (such as from the sheath 160 (Figure 2A) or the inner wall of the lumen 802), such that the biasing rails 120 remain in a single state throughout use. That is, in both advancement of the catheter 100 through the vasculature and ablation of tissue, the catheter 100 is in a state that allows the biasing rails 120 to assume the extended configuration without an external force compressing the biasing rails 120. The shape memory of the multiple biasing rails 120 and the natural biasing of the multiple biasing rails 120 allow the multiple biasing rails 120 to return to a set shape (e.g., the extended configuration). Thus, the angle, shape, curvature, and distance of radial extension of the multiple biasing rails 120 from the catheter body 102 in the extended configuration can be specifically selected. The distance of radial extension of the multiple biasing rails 120 from the catheter body 102 can be specifically selected and / or configured based on the size of the catheter 100 and the size of the blood vessel 300 (FIG. 3A) through which the catheter 100 is advanced. For example, the distance of radial extension of the multiple biasing rails 120 can be selected to bias the catheter 100 against a vessel wall in a vessel having a diameter of about 2 mm to about 4 mm, greater than 4 mm, greater than 6 mm, greater than 8 mm, about 10 mm, etc.

[0033]

[0044] 2A and 2B, in some embodiments, the biasing rails 120 can be user-operated from a low-profile configuration to an extended configuration. For example, in embodiments in which the biasing rails 120 extend proximally (e.g., in the −x direction of the coordinate axes of FIGS. 2A and 2B) through the lumen 802, the biasing rails 120 can extend to a hand control, switch, actuator, or other user-operated device coupled to the biasing rails 120. By actuation of the user-operated device, the user can advance the biasing rails 120 distally (e.g., in the +x direction of the coordinate axes of FIGS. 2A and 2B) through the lumen 802 and / or retract the biasing rails 120 proximally (e.g., in the −x direction of the coordinate axes of FIGS. 2A and 2B) through the lumen. For example, in some embodiments, the biasing rails 120 can be secured to the catheter body 102 at a distal point 132. A user can advance the plurality of biasing rails 120, and in particular the proximal portion 806 of the plurality of biasing rails 120, distally (e.g., in the +x direction of the coordinate axes of FIGS. 2A and 2B), which results in the proximal portion 806 of the plurality of biasing rails 120 extending outwardly from the aperture 808. Thus, the plurality of biasing rails 120 can transition from a low profile configuration depicted in FIG. 2A to an extended configuration depicted in FIG. 2B. In an embodiment, the plurality of biasing rails 120 can be configured to assume a desired shape in the extended configuration following extension of the biasing rails 120 from the aperture 808. In an embodiment, the height of the apex 131 of the plurality of biasing rails 120 in the extended configuration (e.g., in the +z direction of the coordinate axes of FIGS. 2A and 2B) can be determined by the magnitude of distal advancement of the plurality of biasing rails 120 through the lumen 802 (e.g., in the +x direction of the coordinate axes of FIGS. 2A and 2B). In other words, as the user advances the plurality of biasing rails 120 further through the lumen 802 , the plurality of biasing rails 120 can extend further radially from the outer surface of the catheter body 102 .

[0034]

[0045] In other embodiments, the distal points 132 of the multiple biasing rails 120 may also be movable within the lumen 802. In other words, the multiple biasing rails 120 may be fully contained within the lumen 802 proximal to the opening 808 (e.g., in the −x direction of the coordinate axes of FIGS. 2A and 2B). A user may advance the multiple biasing rails 120, such that the multiple biasing rails 120 extend from the opening 808. A user may continue to advance the multiple biasing rails 120 distally (e.g., in the +x direction of the coordinate axes of FIGS. 2A and 2B) until the multiple biasing rails 120 contact the catheter body 102 below the cap 144. The multiple biasing rails 120 may be shaped such that advancement of a distal portion of the multiple biasing rails 120 (e.g., in the +x direction of the coordinate axes of FIGS. 2A and 2B) will induce the distal portion of the multiple biasing rails 120 to move toward the cap 144. Thus, the multiple biasing rails 120 can be selectively manipulated to control the radial extension of the multiple biasing rails 120 from the catheter body 102, as discussed above.

[0035]

[0046] 3A and 3B, an apparatus and method for forming a fistula between a first blood vessel 300 and a second blood vessel 302 by a first catheter 100 and a second catheter 400 will now be discussed. Referring first to FIG. 3A, a first catheter 100 can be advanced in the lumen of the blood vessel 300. A second catheter 400 can be positioned in the blood vessel 302 adjacent to the blood vessel 300. The second catheter 400 can be similar to the first catheter 100 discussed herein. In some embodiments, the second catheter 400 may not include an electrode 108. The second catheter 400 includes a catheter body 402. The catheter body 402 further defines an action site 435 having an active side 434. The second catheter 400 further includes an inactive side 403 defined by the catheter body 402 and the action site 435. In particular, the active side 434 of the working site 435 may include a recess 408 configured to receive the electrode 108 of the first catheter 100. The recess 408 may be specifically shaped, sized, etc. to receive the electrode 108 of the first catheter 100 within the recess 408. In other embodiments, the second catheter 400 may include an electrode extending radially from the working site 435 away from the catheter body 402. The second catheter body 402 of the second catheter 400 may further include one or more magnet arrays. For example, the second catheter 400 may include a first magnet array 404 disposed proximally (e.g., in the −x direction of the coordinate axes of FIGS. 3A and 3B ) relative to the action site 435, a second magnet array 406 disposed distally (e.g., in the +x direction of the coordinate axes of FIGS. 3A and 3B ) relative to the action site 435, and / or a third magnet array 450 disposed along the action site 435, and in some embodiments, particularly along the non-active side 403 of the action site 435. In embodiments, the second catheter 400 may include a second plurality of biasing rails 420 that are similar in structure and operation to the first plurality of biasing rails 120 of the first catheter 100.In the embodiments described below, the first catheter 100 includes a first plurality of biasing rails 120 and the second catheter 400 includes a second plurality of biasing rails 420, although it should be understood that only one of the first catheter 100 and the second catheter 400 may include biasing rails.

[0036]

[0047] The one or more magnet arrays 104, 106, 150 of the first catheter 100 and the one or more magnet arrays 404, 406, 450 of the second catheter 400 can be configured to facilitate rotational and axial alignment of the catheters 100 and 400. Proper axial and rotational alignment between the catheters 100 and 400 can facilitate alignment of one or more fistula forming elements, such as the working sites 135, 435 of the first and second catheters 100, 400, respectively. More specifically, proper axial and rotational alignment between the first catheter 100 and the second catheter 400 can facilitate alignment of the electrode 108 relative to the recess 408. The one or more magnet arrays 104, 106, 150 of the first catheter 100 can be positioned such that the magnetic field generated by the one or more magnet arrays 104, 106, 150 is stronger in the direction of the active side 134 of the action site 135 (e.g., in the −z direction of the coordinate axes of FIGS. 3A and 3B) than in the direction of the inactive side 103 of the action site 135 (e.g., in the +z direction of the coordinate axes of FIGS. 3A and 3B). Similarly, the one or more magnet arrays 404, 406, 450 of the second catheter 400 can be positioned such that the magnetic field generated by the one or more magnet arrays 404, 406, 450 is stronger in the direction of the active side 434 of the action site 435 (e.g., in the +z direction of the coordinate axes of FIGS. 3A and 3B) than in the direction of the inactive side 403 of the action site 435 (e.g., in the −z direction of the coordinate axes of FIGS. 3A and 3B). In such an embodiment, the strength of the magnetic field in the direction of the active sides 134, 434 of the action sites 135, 435, respectively, can promote rotational alignment between the active side 134 of the action site 135 of the first catheter 100 in the first blood vessel 300 and the active side 434 of the action site 435 of the second catheter 400 in the second blood vessel 302.

[0037]

[0048] The catheters 100 and 400 are axially misaligned, as depicted in FIG. 3A, such that the electrode 108 of the first catheter 100 is not aligned with the recess 408 of the second catheter 400 in the x-direction of the coordinate system of FIG. 3A and FIG. 3B. In addition, as depicted, for example, in FIG. 3A, the bond between the first catheter 100 and the second catheter 400 is weak. When the bond is weak, a space may remain between at least one of the active side 134 of the action site 135 of the first catheter 100 and the adjacent wall of the blood vessel 300 and the active side 434 of the action site 435 of the second catheter 400 and the adjacent wall of the blood vessel 302. Thus, when the bond is weak, the active side 134 of the action site 135 and the active side 434 of the action site 435 are not in close proximity to each other (e.g., in the z-direction of the coordinate system of FIG. 3A and FIG. 3B).

[0038]

[0049] Each magnet array 404, 406, 450 of the second catheter 400 may be configured to mate with a corresponding magnet array 104, 106, 150 of the first catheter 100, and vice versa, thereby allowing the first catheter 100 and the second catheter 400 to be aligned and mated. As used herein, the terms "coapted" and / or "strong coaptation" may be understood to mean that the first catheter 100 and the second catheter 400 are in close approximation (e.g., in the direction of the z-axis of the coordinate axes of Figures 3A and 3B) such that the electrodes 108 of the first catheter 100 can enter the recesses 408 of the second catheter 400. As used herein, the term "mate" may be understood to mean a mutual attraction between the magnet arrays of the first catheter 100 and the second catheter 400. For example, a first magnet array 104 disposed proximal to the working site 135 of the catheter 100 (e.g., in the −x direction of the coordinate axes of FIGS. 3A and 3B) can be configured to mate with a first magnet array 404 disposed proximal to the working site 435 of the second catheter 400 (e.g., in the −x direction of the coordinate axes of FIGS. 3A and 3B). A second magnet array 106 disposed distal to the working site 135 of the catheter 100 (e.g., in the +x direction of the coordinate axes of FIGS. 3A and 3B) can be configured to mate with a second magnet array 406 disposed distal to the working site 435 of the second catheter 400 (e.g., in the +x direction of the coordinate axes of FIGS. 3A and 3B). Similarly, the third magnet array 150 positioned along the inactive side 103 of the active site 135 of the first catheter 100 can be configured to mate with the third magnet array 450 positioned along the inactive side 403 of the active site 435 of the second catheter 400.It will be appreciated that the third magnet array 150 of the first catheter 100 and the third magnet array 450 of the second catheter 400 can be configured and arranged to promote bonding between the active side 134 of the action site 135 and the active side 434 of the action site 435 when mated, while the third magnet array 150 and the third magnet array 450 can remain separated (e.g., in the direction of the z-axis of the coordinate axes of Figures 3A and 3B) by the action sites 135, 435.

[0039]

[0050] However, during a fistula formation procedure, the one or more magnetic arrays 104, 106, and 150 of the first catheter 100 and the one or more magnetic arrays 404, 406, and 450 of the second catheter 400 may not be sufficient by themselves to align and join the first catheter 100 and the second catheter 400. For example, the strength limitations of the magnetic array(s) 104, 106, 150 of the first catheter 100 and the magnetic array(s) 404, 406, 450 of the second catheter 400, the flexibility limitations of the first catheter 100 and the second catheter 400, the distance between the vessels 300 and 302, and / or the tortuous anatomical structure of the first blood vessel 300 and / or the second blood vessel 302 may prevent the magnetic array(s) 104, 106, 150 of the first catheter 100 and the magnetic array(s) 404, 406, 450 of the second catheter 400 from mating. Thus, as depicted in FIG. 3A, the first catheter 100 and the second catheter 400 may be axially misaligned and / or may be weakly bonded.

[0040]

[0051] The multiple biasing rails 120 of the first catheter 100 and / or the multiple biasing rails 420 of the second catheter 400 can assist the one or more magnet arrays 104, 106, 150 of the first catheter 100 and the one or more magnet arrays 404, 406, 450 of the second catheter 400 in aligning and joining the first catheter 100 and the second catheter 400. For example, with reference to FIG. 3A, the first catheter 100 and the second catheter 400 can be advanced into the blood vessels 300 and 302 with the multiple biasing rails 120 and / or the multiple biasing rails 420, respectively, in a low profile configuration to facilitate distal advancement of the catheters 100 and 400 (e.g., in the +x direction of the coordinate axes of FIGS. 3A and 3B). The biasing rails 120 of the first catheter 100 and / or the biasing rails 420 of the second catheter 400 can be maintained in a low-profile configuration, for example, by any of the methods discussed above in connection with Figures 1A-2B. With the biasing rails 120 of the first catheter 100 and / or the biasing rails 420 of the second catheter 400 in the low-profile configuration, the first catheter 100 and the second catheter 400 can be advanced into the blood vessels 300 and 302, respectively, after which the working site 135 of the first catheter 100 and the working site 435 of the second catheter 400 are generally positioned at a desired site for forming a fistula between the blood vessels 300 and 302. However, as described above and depicted in FIG. 3A, the one or more magnet arrays 104, 106, 150 of the first catheter 100 and the one or more magnet arrays 404, 406, 450 of the second catheter 400 may not be able to align and join the catheters 100 and 400 by themselves.

[0041]

[0052] 3B, the biasing rails 120 of the first catheter 100 and / or the biasing rails 420 of the second catheter 400 can be transitioned from a low-profile configuration to an extended configuration to facilitate alignment and mating between the first catheter 100 and the second catheter 400. In some embodiments, only the biasing rails 120 of the first catheter 100 can be transitioned from a low-profile configuration to an extended configuration to facilitate alignment and mating between the first catheter 100 and the second catheter 400. In some embodiments, only the biasing rails 420 of the second catheter 400 can be transitioned from a low-profile configuration to an extended configuration to facilitate alignment and mating between the first catheter 100 and the second catheter 400. In embodiments, the biasing rails 120 and / or the biasing rails 420 can be transitioned from a low-profile configuration to an extended configuration by any device or method discussed with reference to FIGS. 1A-2B.

[0042]

[0053] In embodiments in which the biasing rails 120 and 420 are naturally biased from the low-profile configuration to the extended configuration, the biasing rails 120 and 420 can begin to extend radially away from the catheter body 102 and 402, respectively. For example, the biasing rails 120 can extend toward the maximum height MH of the extended configuration (FIG. 1A) until the biasing rails 120 contact the wall of the blood vessel 300. Thus, the biasing rails 120 can apply a biasing force against the wall of the blood vessel 300, resulting in a counter-bias force being applied to the catheter 100 to press the active side 134 and / or the one or more magnetic arrays against the wall of the blood vessel 300. More specifically, because the lateral center point 137 (FIG. 1B) of the multiple biasing rails 120 is located directly opposite the active side 134 of the action site 135, the biasing reaction force can guide the active side 134 of the action site 135 against the wall of the blood vessel 300 at a position directly opposite the lateral center point 137 (FIG. 1B) of the multiple biasing rails 120.

[0043]

[0054] Similarly, the multiple biasing rails 420 of the second catheter 400 can transition to an extended configuration to contact the wall of the second blood vessel 302 such that a biasing reaction force guides the active side 434 of the action site 435 of the second catheter 400 against the wall of the second blood vessel 302. For example, the biasing rails 420 of the second catheter 400 can be deployed when the active side 434 of the action site 435 of the second catheter 400 is substantially aligned with the active side 134 of the action site 135 of the first catheter 3100. Thus, the multiple biasing rails 3120 and 420 can enhance the bond between the first catheter 100 and the second catheter 400. For example, as described above, the multiple biasing rails 120 of the first catheter 100 can bias one or more magnet arrays 104, 106, 150 against the walls of the first blood vessel 300 in addition to the active side 134 of the action site 135, and the biasing rail 420 of the second catheter 400 can bias one or more magnet arrays 404, 406, 450 against the walls of the second blood vessel 302 in addition to the active side 434 of the action site 435, thereby increasing the attractive force between the one or more magnet arrays 104, 105, 150 of the first catheter and the one or more magnet arrays 404, 406, 450 by reducing the distance therebetween. For example, after close proximity, the one or more magnet arrays 104, 106, 150 of the first catheter 100 and the one or more magnet arrays 404, 406, 450 of the second catheter 400 can be mated, overcoming all of the aforementioned barriers such as the distance between the magnets, the flexibility of the catheters 100, 400, the distance between the vessels 300, 302, the tortuous anatomical structures of the first blood vessel 300 and the second blood vessel 302, etc. The mating of the one or more magnet arrays 104, 106, 150 of the first catheter 100 and the one or more magnet arrays 404, 406, 450 of the second catheter 400 can join and align the catheters 100 and 400.After the first catheter 100 and the second catheter 400 are joined and aligned, the electrode 108 can be advanced and energized to cauterize the walls of the first blood vessel 300 and the second blood vessel 302 and advanced into the recess 408 of the second catheter 400, thereby forming a fistula between the first blood vessel 300 and the second blood vessel 302.

[0044]

[0055] Referring now to FIG. 4, a side view of a catheter 200 is depicted. The catheter 200 can be similar to the catheter 100 discussed in FIGS. 1A-3B in all aspects except those discussed herein. For example, similar to the catheter 100, the catheter 200 can include a catheter body 102 defining an action site 135 and one or more magnet arrays 104, 106, 150. The action site 135 can include an active side 134 diametrically opposed to the inactive side 103. The catheter 200 includes a plurality of biasing rails 120 that can be radially arced away from the catheter body 102 between a proximal point 130 and a distal point 132. Unlike the catheter 100 discussed above, the distal point 132 of the catheter 200 can be located along the inactive side 103 of the action site 135. In such an embodiment, the first magnet array 104 can be located between the proximal point 130 and the distal point 132. In embodiments, the distal point 132 can be located longitudinally along the third magnet array 150 (e.g., in the direction of the x-axis of the coordinate axes of FIG. 4). In embodiments, the location of the distal point 132 and / or the location and / or length of the third magnet array 150 can be adjusted such that the third magnet array 150 is located between the proximal point 130 and the distal point 132 (e.g., in the direction of the x-axis of the coordinate axes of FIG. 4). In some embodiments, the proximal point 130 can be located along the inactive side 103 of the working site 135, and the distal point 132 can be located at the proximal end of the distal tip 140 (e.g., in the −x direction of the coordinate axes of FIG. 4) such that the second magnet array 106 is located between the proximal point 130 and the distal point 132. In such embodiments, the third magnet array 150 can be located between the proximal point 130 and the distal point 132. Similar to catheter 100, the multiple biasing rails 120 of catheter 200 may be coupled to the catheter body 102 at a proximal point 130 or may be movable within the lumen of the catheter body 102, and the multiple biasing rails 120 may be coupled to the catheter body 102 at a distal point 132 or may be movable within the lumen of the catheter body 102.

[0045]

[0056] Referring now to FIG. 5, a side view of a catheter 500 is depicted. The catheter 500 can be similar to the catheter 100 discussed in FIGS. 1A-3B in all aspects except those discussed herein. For example, similar to the catheter 100, the catheter 500 can include a catheter body 102 defining an active site 135 and one or more magnet arrays 104, 106, 150. The active site 135 can include an active side 134 diametrically opposed to the inactive side 103. The catheter 500 includes a plurality of biasing rails 120. Unlike the catheter 100, the plurality of biasing rails 120 of the catheter 500 can define a first arch 510 and a second arch 520. The first arch 510 can extend radially away from the catheter body 102 between a proximal point 130 and a midpoint 530. The second arch 520 can extend radially away from the catheter body 102 between a midpoint 530 and a distal point 132. In an embodiment, the midpoint 530 can be along or within the inactive side 103 of the working site 135. In an embodiment, the first plurality of magnets 104 can be disposed between the proximal point 130 and the midpoint 530 (e.g., in the direction of the x-axis of the coordinate axis of FIG. 5). In some embodiments, the third magnet array 150 can be disposed between the proximal point 130 and the midpoint 530 (e.g., in the direction of the x-axis of the coordinate axis of FIG. 5). In some embodiments, the midpoint 530 can be disposed longitudinally along the third magnet array 150 (e.g., in the direction of the x-axis of the coordinate axis of FIG. 5). In an embodiment, the third magnet array 150 can be disposed between the midpoint 530 and the distal point 132 (e.g., in the direction of the x-axis of the coordinate axis of FIG. 5). In an embodiment, the second magnet array 106 can be located between the intermediate point 530 and the distal point 132. Similar to the catheter 100, the multiple biasing rails 120 of the catheter 500 can be coupled to the catheter body 102 at a proximal point 130 or can be movable within a lumen of the catheter body 102, and the multiple biasing rails 120 can be coupled to the catheter body 102 at a distal point 132 or can be movable within a lumen of the catheter body 102.In an embodiment, the multiple biasing rails 120 may be coupled to the non-active side 103 of the working site 135 at an intermediate point 503. In an embodiment, the multiple biasing rails 120 may pass through a lumen of the catheter 500 at an intermediate point 530. In such an embodiment, the multiple biasing rails 120 may be movable within the lumen of the catheter 500 at the intermediate point 530.

[0046]

[0057] Referring now to FIG. 6, a side view of a catheter 600 is depicted. The catheter 600 can be similar to the catheter 100 discussed in FIGS. 1A-3B in all aspects except those discussed herein. For example, similar to the catheter 100, the catheter 600 can include a catheter body 102 defining an active site 135 and one or more magnet arrays 104, 106, 150. The active site 135 can include an active side 134 diametrically opposed to the inactive side 103. The catheter 600 includes a plurality of biasing rails 120. Unlike the catheter 100, the plurality of biasing rails 120 of the catheter 600 can define a first biasing rail in the form of a first loop 610 and a second biasing rail in the form of a second loop 620. The first loop 610 can extend distally from a proximal point 130 (e.g., in the +x direction of the coordinate axis of FIG. 6). The second loop 620 can extend in a proximal direction (e.g., in the −x direction of the coordinate axes of FIG. 6 ) from the distal point 132. The first loop 610 is defined by a strip of biasing rail material that extends from the catheter body 102 at the proximal point 130 and returns to the catheter body 102 at the proximal point 130. The second loop 620 is defined by a strip of biasing rail material that extends from the catheter body 102 at the distal point 132 and returns to the catheter body 102 at the distal point 132. The first loop 610 can be intertwined with the second loop 620 at the intersection 630. Thus, a portion of the first loop 610 can be within the second loop 620 and a portion of the second loop 620 can be within the first loop 610. The one or more connecting rails 126 can extend laterally between the first loops 610 at a point between the longitudinal direction (e.g., along the x-axis of the coordinate axes in FIG. 6 ) of the proximal point 130 and the intersection point 630. The one or more connecting rails 126′ can extend laterally between the second loops 620 at a point between the longitudinal direction of the intersection point 630 and the distal point 132.Similar to catheter 100, the multiple biasing rails 120 of catheter 600 may be coupled to the catheter body 102 at a proximal point 130 or may be movable within the lumen of the catheter body 102, and the multiple biasing rails 120 may be coupled to the catheter body 102 at a distal point 132 or may be movable within the lumen of the catheter body 102.

[0047]

[0058] Referring now to FIG. 7, a side view of a catheter 700 is depicted. The catheter 700 may be similar to the catheter 100 discussed in FIGS. 1A-3B in all aspects except those discussed herein. For example, similar to the catheter 100, the catheter 700 may include a catheter body 102 defining an active site 135 and one or more magnet arrays 104, 106, 150. The active site 135 may include an active side 134 diametrically opposed to the inactive side 103. The catheter 700 includes multiple biasing rails 120. Unlike the catheter 100, the multiple biasing rails 120 of the catheter 700 may define a substantially helical structure that is wrapped circumferentially around the catheter body 102 between the proximal point 130 and the distal point 132. It should be appreciated that in some embodiments, the catheter 700 may include a single biasing rail, such as the biasing rail 122 or 124, such as a helical section around the catheter body 102. The multiple biasing rails 120 can extend radially away from the catheter body 102 at a proximal point 130 and a distal point 132. The multiple biasing rails 120 can have any desired amplitude. The multiple biasing rails 120 can have any desired pitch. In an embodiment, any or all of the one or more magnet arrays 104, 106, 150 can be between the proximal point 130 and the distal point 132 (e.g., in the direction of the x-axis of the coordinate axes of FIG. 7). Similar to the catheter 100, the multiple biasing rails 120 of the catheter 700 can be coupled to the catheter body 102 at the proximal point 130 or can be movable within the lumen of the catheter body 102, and the multiple biasing rails 120 can be coupled to the catheter body 102 at the distal point 132 or can be movable within the lumen of the catheter body 102.

[0048]

[0059] In some embodiments, the plurality of biasing rails 120 may be positioned such that a first distance H1 between the catheter body 102 and the apex 131 of the plurality of biasing rails 120 diametrically opposite the active side 134 of the working site 135 is substantially equal to a second distance H2 between the catheter body 102 and the apex 702 of the plurality of biasing rails 120 diametrically opposite the inactive side 103 of the working site 135. In other embodiments, the second distance H2 between the catheter body 102 and the apex 702 of the plurality of biasing rails 120 diametrically opposite the inactive side 103 of the working site 135 may be minimized. In such embodiments, the apex 702 of the plurality of biasing rails 120 may abut the catheter body 102. Thus, the plurality of biasing rails 120 may not extend radially from the catheter body 102 diametrically opposite the inactive side 103 of the working site 135. In such an embodiment, the apex 131 of the multiple biasing rails 120 can extend radially from the catheter body at any desired first distance H1 diametrically opposite the active side 134 of the action site 135. In such an embodiment, the apex 131 of the multiple biasing rails 120 can contact the wall of the blood vessel 300 (FIG. 3A) at a point diametrically opposite the active side 134 of the action site 135. Thus, the multiple biasing rails 120 can bias the active side 134 of the action site 135 against the wall of the blood vessel 300 (FIG. 3A) diametrically opposite the contact point between the apex 131 of the multiple biasing rails 120 and the wall of the blood vessel 300 (FIG. 3A). In an embodiment, the multiple biasing rails 120 can be secured to the catheter body 102 at a proximal point 130 and a distal point 132. In such an embodiment, when the multiple biasing rails 120 contact the wall of the blood vessel 300 (FIG. 3A) at a point (e.g., apex 131) located diametrically opposite the active side 134 of the action site 135, the multiple biasing rails 120 can generate an opposing force that buckles the catheter body 102 between the proximal point 130 and the distal point 132, thereby moving the non-active side 103 of the catheter 700 to the position depicted by the dashed line 103′.Thus, the action site 135 and one or more magnet arrays 104, 106, 150 can be biased against a wall of the blood vessel 300 (FIG. 3A) located directly opposite the contact point between the apex 131 of the multiple biasing rails 120 and the wall of the blood vessel 300 (FIG. 3A).

[0049]

[0060] Embodiments may be described with reference to the following numerical terms:

[0061] 1. A device for forming a fistula between two blood vessels, comprising: a first catheter comprising a first catheter body, an electrode, one or more magnetic arrays, and a first plurality of biasing rails, the electrode configured to protrude from an active site of the first catheter and to define an active side of the first catheter, the one or more magnetic arrays disposed longitudinally along the first catheter body, the first plurality of biasing rails extending longitudinally along a length of the first catheter body, and at least one of the one or more magnetic arrays configured to longitudinally straddle at least one of the one or more magnetic arrays. The catheter body is configured to radially arc away from the first catheter body between a proximal point positioned proximal to a first end of at least one of the one or more magnet arrays and a distal point positioned distal to a second end of at least one of the one or more magnet arrays, a first plurality of biasing rails extending from a non-active side of the first catheter body such that the first plurality of biasing rails are configured to bias the active site and the one or more magnet arrays against the first vessel wall, the first plurality of biasing rails being connected by a connecting rail extending laterally between the first plurality of biasing rails at a point between the proximal and distal points.

[0050]

[0062] 2. The device of paragraph 1, wherein the working site is positioned longitudinally between the proximal point and the distal point.

[0063] 3. The device of any preceding paragraph, wherein the distal point is positioned on the inactive side of the working site.

[0051]

[0064] 4. The device of any preceding paragraph, wherein the first plurality of biasing rails comprises: a first loop extending distally from a proximal point; and a second loop extending proximally from a distal point, the first loop and the second loop being intertwined at an intersection between the proximal and distal points.

[0052]

[0065] 5. The device of any preceding paragraph, wherein a first plurality of biasing rails are coupled to the first catheter body at a midpoint between the proximal and distal points.

[0066] 6. The device of any preceding paragraph, wherein the midpoint is positioned longitudinally along the working site opposite the electrode.

[0053]

[0067] 7. The device of any preceding paragraph, wherein the first plurality of biasing rails define a helix extending circumferentially around the first catheter body between a proximal point and a distal point.

[0068] 8. The device of any preceding paragraph, wherein the distal point is positioned proximal to the distal tip of the first catheter body.

[0054]

[0069] 9. The device of any preceding paragraph, wherein a first plurality of biasing rails are fixedly coupled to the first catheter body at distal and proximal points by an adhesive or polymer.

[0070] 10. The device of any preceding paragraph, wherein one of the proximal and distal points defines an access opening into a lumen within the first catheter body, and the plurality of biased rails are configured to slide within the lumen of the first catheter body between an extended position and a low-profile position.

[0055]

[0071] 11. The device of any preceding paragraph, wherein the first catheter further comprises a sleeve configured to be advanced distally to compress the first plurality of biasing rails against the first catheter body.

[0056]

[0072] 12. The device of any preceding clause, wherein the first plurality of biasing rails comprises nitinol, stainless steel, polyetheretherketone, polyethyleneterephthalate, polyimide, or polytetrafluoroethylene.

[0057]

[0073] 13. The device of any preceding paragraph, wherein the first plurality of biasing rails includes a circular cross-section.

[0074] 14. The device of any preceding paragraph, wherein the first plurality of biasing rails comprises a substantially flat ribbon having a substantially rectangular cross-section.

[0058]

[0075] 15. The device of any preceding clause, further comprising a second catheter, the first catheter configured to be positioned within a first blood vessel and the second catheter configured to be positioned within a second blood vessel adjacent to the first blood vessel.

[0059]

[0076] 16. The device of any preceding clause, wherein the second catheter further comprises a recessed region defining an active side of the second catheter, the recessed region configured to receive an electrode of the first catheter.

[0060]

[0077] 17. The device of any preceding clause, wherein the second catheter further comprises a second catheter body and one or more magnet arrays disposed longitudinally along the second catheter body.

[0061]

[0078] 18. The device of any preceding clause, wherein the second catheter further comprises: a second plurality of biasing rails extending longitudinally along a length of the second catheter body and configured to longitudinally straddle at least one of the one or more magnetic arrays and arc radially away from the second catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnetic arrays of the second catheter and a distal point positioned distal to a second end of the at least one of the one or more magnetic arrays of the second catheter, the second plurality of biasing rails extending from a non-active side of the second catheter body such that the second plurality of biasing rails are configured to bias the recessed region and the one or more magnetic arrays of the second catheter against the second vessel wall, and the second plurality of biasing rails are connected by a connecting rail extending laterally between the second plurality of biasing rails at a point between the proximal and distal points.

[0062]

[0079] 19. The device of any preceding paragraph, wherein the concave region is positioned longitudinally between the proximal and distal points.

[0080] 20. A method of forming a fistula between a first blood vessel and a second blood vessel, comprising: advancing a first catheter into the first blood vessel, the first catheter comprising a first catheter body, an electrode, one or more magnet arrays, and a first plurality of biasing rails, the electrode configured to protrude from an active site of the first catheter and to define an active side of the first catheter, the one or more magnet arrays disposed longitudinally along the first catheter body, the first plurality of biasing rails extending longitudinally along a length of the first catheter body, and at least one of the one or more magnet arrays being biased longitudinally along the length of the first catheter body. forming a fistula, the fistula being configured to arch radially away from the first catheter body between a proximal point positioned proximal to a first end of at least one of the one or more magnet arrays and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays so as to span the first blood vessel wall, a first plurality of biasing rails extending from a non-active side of the first catheter body such that the first plurality of biasing rails are configured to bias the action site and the one or more magnet arrays against the first blood vessel wall; and cauterizing tissue with the electrode to form the fistula.

[0063]

[0081] 21. The method of paragraph 20, wherein the working site is positioned longitudinally between the proximal and distal points.

[0082] 22. The method of any preceding clause, further comprising advancing a second catheter into the second blood vessel and aligning the electrode of the first catheter with the second catheter.

[0064]

[0083] 23. The method of any preceding clause, wherein the second catheter comprises a recess, and aligning an electrode of the first catheter with the second catheter includes aligning the electrode with the recess.

[0065]

[0084] 24. The method of any preceding clause, wherein the second catheter further comprises a second catheter body and one or more magnet arrays disposed longitudinally along the second catheter body, and wherein the electrodes of the first catheter are aligned with the second catheter via the one or more magnet arrays of the first catheter and the one or more magnet arrays of the second catheter.

[0066]

[0085] 25. The method of any preceding clause, wherein the second catheter further comprises: a second plurality of biasing rails extending longitudinally along a length of the second catheter body and configured to longitudinally straddle at least one of the one or more magnetic arrays and to arc radially away from the second catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnetic arrays of the second catheter and a distal point positioned distal to a second end of the at least one of the one or more magnetic arrays of the second catheter, the second plurality of biasing rails extending from a non-active side of the second catheter body such that the second plurality of biasing rails are configured to bias the recess and the one or more magnetic arrays of the second catheter against the second vessel wall.

[0067]

[0086] 26. The method of any preceding paragraph, wherein the recess is positioned longitudinally between the proximal point and the distal point.

[0087] 27. A device for forming a fistula between two blood vessels, comprising: a first catheter comprising a catheter body, an electrode, one or more magnet arrays, and a plurality of biasing rails, the electrode configured to project from an active site of the first catheter and to define an active side of the first catheter, the one or more magnet arrays disposed longitudinally along the catheter body, the plurality of biasing rails extending longitudinally along the length of the catheter body, the plurality of biasing rails arching radially away from the catheter body between a proximal point positioned proximal to a first end of at least one of the one or more magnet arrays and a distal point positioned distal to a second end of at least one of the one or more magnet arrays so as to longitudinally straddle at least one of the one or more magnet arrays. a plurality of biasing rails extending from a non-active side of the catheter body such that the plurality of biasing rails are configured to bias the active site and the one or more magnetic arrays against the first vessel wall, the plurality of biasing rails being connected by a connecting rail extending laterally between the plurality of biasing rails at a point between a proximal point and a distal point, the plurality of biasing rails comprising a proximal portion extending through a lumen of the catheter body, the proximal portion being advanceable within the lumen to transition the plurality of biasing rails to an extended configuration, the plurality of biasing rails arching radially away from the catheter body, the proximal portion being retractable within the lumen to transition the plurality of biasing rails to a low-profile configuration, a maximum radial deflection distance of the plurality of biasing rails being less than a maximum radial deflection distance of the plurality of biasing rails in the extended configuration.

[0068]

[0088] 28. The device of paragraph 27, wherein the plurality of biasing rails are naturally biased from the low-profile configuration to the extended configuration.

[0089] 29. The device of any preceding clause, wherein the first catheter further comprises a sleeve configured to be advanced distally to maintain the first plurality of biased rails in a low-profile configuration.

[0069]

[0090] 30. The device of any preceding paragraph, wherein the plurality of biasing rails are substantially flush with or within the catheter body when in the low profile configuration.

[0091] It should now be appreciated that embodiments of the present disclosure are directed to devices, apparatus, and methods for forming a fistula between two blood vessels. For example, a catheter may include a catheter body, an electrode, a first magnet array, and a first plurality of biasing rails. The electrode is configured to protrude from an action site of the catheter. The first magnet array is disposed longitudinally along the catheter body. The first plurality of biasing rails extend longitudinally along the length of the catheter body and are configured to arc radially away from the catheter body between a proximal point of the first plurality of biasing rails and a distal point of the first plurality of biasing rails. The first plurality of biasing rails are connected by a connecting rail extending laterally between the first plurality of biasing rails at a point between the proximal point of the first plurality of biasing rails and the distal point of the first plurality of biasing rails. The first plurality of biasing rails span the first magnetic array longitudinally and extend from the inactive side of the catheter body such that the first plurality of biasing rails are configured to bias the action site and the first magnetic array against the first vessel wall, thus improving the ability of the catheter to form a fistula.

[0070]

[0092] It should be noted that the terms "substantially" and "about" may be utilized herein to express the inherent indeterminacy that may result from any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to express the extent to which a quantitative representation may vary from the stated basis without causing a change in the basic functionality of the subject matter at issue.

[0071]

[0093] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that fall within the scope of the claimed subject matter.

Claims

1. An apparatus for forming a fistula between a first blood vessel and a second blood vessel, comprising: A first catheter comprising a first catheter body, an electrode, one or more magnet arrays, and a first plurality of bias rails. Equipped with the electrode is configured to protrude from an action site of the first catheter and to define an active side of the first catheter body; the first catheter body having an inactive side disposed opposite the active side; the one or more magnet arrays are disposed longitudinally along the first catheter body; the first plurality of biasing rails extend longitudinally along a length of the first catheter body and are configured to longitudinally straddle at least one of the one or more magnet arrays and to arc radially away from the first catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnet arrays and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays; the first plurality of biasing rails extending from the non-active side of the first catheter body, whereby the first plurality of biasing rails are configured to bias the application site and the one or more magnet arrays against a wall of the first blood vessel; the first plurality of biasing rails are connected by a connecting rail extending laterally between the first plurality of biasing rails at a point between the proximal point and the distal point; Device.

2. The device of claim 1 , wherein the working site is positioned longitudinally between the proximal point and the distal point.

3. The device of claim 1 , wherein the distal point is positioned on the non-active side of the working site.

4. The first plurality of biasing rails include: a first loop extending distally from the proximal point; a second loop extending proximally from the distal point; Equipped with The device of claim 1 , wherein the first loop and the second loop are intertwined at an intersection between the proximal point and the distal point.

5. The apparatus of claim 1 , wherein the first plurality of biasing rails are coupled to the first catheter body at a point midway between the proximal point and the distal point.

6. The device of claim 5 , wherein the midpoint is positioned longitudinally along the working site opposite the electrode.

7. The apparatus of claim 1 , wherein the first plurality of biasing rails define a helix extending circumferentially around the first catheter body between the proximal point and the distal point.

8. The apparatus of claim 1 , wherein the distal point is positioned proximal to a distal tip of the first catheter body.

9. The apparatus of claim 8 , wherein the first plurality of biasing rails are fixedly coupled to the first catheter body at the distal and proximal points by an adhesive or polymer.

10. 9. The apparatus of claim 8, wherein one of the proximal point and the distal point defines an access opening into a lumen in the first catheter body, and the plurality of biased rails are configured to slide within the lumen of the first catheter body between an extended position and a low-profile position.

11. The apparatus of claim 1 , wherein the first catheter further comprises a sleeve configured to be advanced distally to compress the first plurality of biasing rails against the first catheter body.

12. The apparatus of claim 1 , wherein the first plurality of biasing rails comprises nitinol, stainless steel, polyetheretherketone, polyethyleneterephthalate, polyimide, or polytetrafluoroethylene.

13. The apparatus of claim 1 , wherein the first plurality of biasing rails comprises a circular cross-section.

14. The apparatus of claim 1 , wherein the first plurality of biasing rails comprises a substantially flat ribbon having a substantially rectangular cross-section.

15. 10. The apparatus of claim 1, further comprising a second catheter, the first catheter configured to be positioned within the first blood vessel and the second catheter configured to be positioned within the second blood vessel adjacent the first blood vessel.

16. 16. The apparatus of claim 15, wherein the second catheter further comprises a second catheter body and a recessed area defining an active side of the second catheter body, the recessed area configured to receive the electrode of the first catheter.

17. The apparatus of claim 16 , wherein the second catheter further comprises one or more magnet arrays disposed longitudinally along the second catheter body.

18. the second catheter comprising: A second plurality of biasing rails Further equipped with the second plurality of biasing rails extend longitudinally along a length of the second catheter body and are configured to longitudinally straddle at least one of the one or more magnet arrays and to arc radially away from the second catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnet arrays of the second catheter and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays of the second catheter; the second plurality of biasing rails extend from a non-active side of the second catheter body disposed opposite the active side of the second catheter body, whereby the second plurality of biasing rails are configured to bias the recessed area and the one or more magnet arrays of the second catheter against a wall of the second blood vessel; the second plurality of biasing rails are connected by a connecting rail extending laterally between the second plurality of biasing rails at a point between the proximal point and the distal point.

20. The apparatus of claim 17.

19. The device of claim 18 , wherein the recessed region is positioned longitudinally between the proximal point and the distal point.

20. An apparatus for forming a fistula between a first blood vessel and a second blood vessel, comprising: A first catheter comprising a catheter body, an electrode, one or more magnet arrays, and a plurality of biasing rails. Equipped with the electrode is configured to protrude from an action site of the first catheter and to define an active side of the catheter body; the catheter body having an inactive side disposed opposite the active side; the one or more magnet arrays are disposed longitudinally along the catheter body; the plurality of biasing rails extend longitudinally along the length of the catheter body; the plurality of biasing rails are configured to longitudinally straddle at least one of the one or more magnet arrays and to radially arc away from the catheter body between a proximal point positioned proximal to a first end of the at least one of the one or more magnet arrays and a distal point positioned distal to a second end of the at least one of the one or more magnet arrays; the plurality of biasing rails extending from the non-active side of the catheter body, the plurality of biasing rails configured to bias the application site and the one or more magnet arrays against a wall of the first blood vessel; the plurality of biasing rails are connected by a connecting rail extending laterally between the plurality of biasing rails at a point between the proximal point and the distal point; the plurality of biasing rails having a proximal portion extending through a lumen of the catheter body; The proximal portion can be advanced within the lumen to transition the plurality of biasing rails to an extended configuration, the plurality of biasing rails arching radially away from the catheter body; the proximal portion can be retracted within the lumen to transition the plurality of biasing rails to a low-profile configuration, a maximum radial deflection distance of the plurality of biasing rails being less than a maximum radial deflection distance of the plurality of biasing rails in the extended configuration; Device.

21. The apparatus of claim 20 , wherein the plurality of biased rails are naturally biased from the low-profile configuration to the extended configuration.

22. 22. The apparatus of claim 21, wherein the first catheter further comprises a sleeve configured to be advanced distally to maintain the plurality of biased rails in the low-profile configuration.

23. 21. The apparatus of claim 20, wherein the plurality of biasing rails are substantially flush with or within the catheter body in the low profile configuration.

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