Single or multiple loop snares and methods for forming same

Abstract

The surgical snare has a plurality of filaments braided together to form a braided tubular construct comprising a proximal tube and a distal tube. The loop region comprises at least one loop disposed between the proximal tube and the distal tube. The distal tube is inserted into the proximal tube such that the at least one loop extends distal to the distal end of the proximal tube in the form of at least one loop, and the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the at least one loop.

Description

[Technical Field]

[0001] (Reference to prior pending patent application) This patent application claims the benefit of pending prior U.S. Provisional Patent Application No. 63 / 417,498, filed October 19, 2022 by Phase One Medical, LLC for Universal Braided Structure to Form Single-Loop or Multiple-Loop Snare (Attorney Docket No. RAVENSCROFT-4 PROV).

[0002] The above patent applications are incorporated herein by reference.

[0003] The present invention relates generally to medical devices, and more particularly to surgical snares and novel methods of manufacturing surgical snares. [Background technology]

[0004] In recent years, several medical devices have been developed that may be used to retrieve and / or manipulate objects within the cardiovascular system or hollow viscera during surgical procedures. Such devices are commonly referred to in the art as "snares" or "baskets" (collectively "snares").

[0005] Prior art surgical snares are typically fabricated from shape memory materials, nickel-cobalt alloys (e.g., MP35N), stainless steel, and / or medical-grade polymers and elastomers. Prior art surgical snares generally include one or more loops joined at their proximal ends to the distal end of a shaft (e.g., a rigid or semi-rigid shaft having sufficient column strength to advance the snare through tortuous paths).

[0006] In use, prior art surgical snares are generally folded (e.g., assume a smaller profile) and configured to be passed through the lumen of a catheter, which is then inserted into a patient's body (e.g., into the patient's vascular system). The catheter is advanced to a desired location within the patient's body, and the snare is then moved distally relative to the catheter, thereby allowing the snare loops, no longer confined within the catheter lumen, to naturally expand within a blood vessel or hollow viscus at the distal end of the catheter.

[0007] After the snare loop is advanced distally from the catheter lumen and appropriately expanded, the loop may be used to perform a surgical procedure. By way of example and not limitation, the loop may be advanced over a foreign body, and then the loop may be contracted to close the loop around the foreign body by distally advancing a catheter over the snare shaft. Once captured within the loop, the foreign body may be manipulated within the patient's body or may be completely removed from the patient's body, such as by proximally retracting the snare and the foreign body captured within the loop, or by capturing the foreign body between the loop and the distal end of the catheter and withdrawing the catheter proximally.

[0008] Minimally invasive cardiovascular procedures typically begin by establishing safe access to a vein or artery, whereby surgical instruments (e.g., catheters, snares, balloons, etc.) may be advanced intraluminally through the vein or artery. The Seldinger technique is by far the most common technique used to establish safe access to a vein or artery. With the Seldinger technique, the desired vessel (i.e., the vein or artery to be accessed) is first pierced with a sharp, hollow needle, and a guidewire is advanced distally into the vessel through the lumen of the hollow needle. The needle is then withdrawn proximally relative to the guidewire and removed from the proximal end of the guidewire, leaving the guidewire disposed within the vessel. Once access is achieved and the guidewire is in place, the guidewire is carefully and skillfully advanced through the vascular system to position the distal end of the guidewire at the target location. The guidewire provides a “monorail” for safely and efficiently introducing other medical devices into the body and then moving the medical device along the guidewire to the target location.

[0009] By way of example and not limitation, a physician may first insert a hemostatic introducer sheath (e.g., a valved catheter) over the guidewire to increase the diameter of the "working channel" through which other medical devices may be passed into the patient's blood vessels (while minimizing blood loss). Because this technique is common, many medical devices configured for endoluminal insertion into the body, such as stents, grafts, angioplasty balloons, drug delivery catheters, imaging catheters, etc., are configured to receive a guidewire through a central lumen formed within the medical device.

[0010] However, prior art snare designs do not include a central lumen for receiving a guidewire, thereby forcing the user to remove the guidewire from the introducer sheath / catheter before inserting the snare into the introducer sheath / catheter so that there is sufficient space within the introducer sheath / catheter to receive the snare. And with prior art snares, once the physician is done using the snare, if additional medical devices are to be inserted through the introducer sheath / catheter, the physician must reinsert and reposition the guidewire, thereby significantly increasing procedural risks (e.g., loss of access, guidewire contamination, etc.).

[0011] Currently, commercially available snares are fabricated from individual cables (e.g., the En-Snare® surgical snare manufactured by Merit Medical Systems, Inc. of Jordan, Utah, USA) that are joined together at the distal end of a shaft, or from a wire-coiled filament (e.g., the Amplatz Goose Neck™ surgical snare manufactured by Medtronic plc of Minneapolis, Minnesota, USA). Manufacturing snares with individual cables or filaments wound with a wire coil is extremely labor-intensive, and each such snare design (single-loop or multi-loop) requires different materials and assembly methods, thereby complicating the manufacture of prior art snares. Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, there is a need for a new and improved surgical snare that includes a central lumen for receiving a guidewire and that is less complicated to manufacture than prior art surgical snares. [Means for solving the problem]

[0013] The present invention involves the provision and use of a new and improved surgical snare that is manufactured as a braided tubular braid construction with a central lumen for receiving a guidewire.

[0014] A unique benefit of forming the snare of the present invention as a tubular braid construction is that all of the filaments comprising the tubular braid are braided together (thereby enhancing the mechanical integrity of the snare) and the tubular braid structure, by being formed as a tube, inherently has a central lumen for facilitating passage of a guidewire. More specifically, the novel snare of the present invention provides improved mechanical integrity and a structure that may be formed into a single-loop or multi-loop snare, while ultimately significantly reducing the costs associated with manufacturing the novel snare.

[0015] In a preferred form of the invention, there is provided a method of forming a surgical snare, comprising the steps of: providing a plurality of filaments; Braiding a plurality of filaments together to form a braided tubular construction, the braided tubular construction comprising: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube, the loop region comprising at least one loop structure comprising at least three of the plurality of filaments braided together; braiding, (i) disposing the distal tube within the proximal tube lumen such that the at least one loop structure extends distally of the distal end of the proximal tube in the form of at least one loop; and (ii) inserting the distal end of the distal tube into the open distal end of the proximal tube and into the proximal tube lumen such that the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the at least one loop; A method is provided which includes:

[0016] In another preferred form of the present invention, there is provided a surgical snare comprising a braided tubular construction formed by braiding together a plurality of filaments, the construction comprising: The braided tubular structure comprises: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube; the loop region comprising a plurality of solid loop structures, each of the plurality of solid loop structures comprising at least three of the plurality of filaments braided together; A surgical snare is provided in which the distal end of the distal tube is inserted into the open distal end of the proximal tube and into the proximal tube lumen such that (i) the distal tube is disposed within the proximal tube lumen and the plurality of solid loop structures extend distal to the distal end of the proximal tube in the form of a plurality of loops, and (ii) the distal tube lumen extends from a point located distal to the proximal end of the proximal tube to the plurality of loops.

[0017] In another preferred form of the present invention, there is provided a method of forming a surgical snare, comprising the steps of: Prepare 24 filaments, braiding 24 filaments together to form a braided tubular construction, the braided tubular construction comprising: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and braiding a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube, the loop region comprising three solid loop structures, each of the three solid loop structures comprising eight filaments braided together; radially constraining the distal tube during braiding thereof such that the distal tube has a radius smaller than a radius of the distal tube lumen; (i) inserting the distal end of the distal tube into the open distal end of the proximal tube and into the proximal tube lumen such that the distal tube is disposed within the proximal tube lumen and the three solid loop structures extend distally of the distal end of the proximal tube in the form of three loops; and (ii) the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the three loops. A method is provided which includes:

[0018] In another preferred form of the present invention, there is provided a method of forming a surgical snare, comprising the steps of: providing a plurality of filaments; braiding the plurality of filaments together to form a braided tubular construction, the braided tubular construction comprising: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and braiding a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube, the loop region comprising a plurality of solid loop structures, each of the plurality of solid loop structures comprising at least three of the plurality of filaments braided together; rotating at least one of the proximal tube and the distal tube relative to the other of the proximal tube and the distal tube about a central longitudinal axis of the distal tube such that the plurality of solid loop structures are twisted together to form a single solid loop structure; (i) inserting the distal end of the distal tube into the open distal end of the proximal tube and into the proximal tube lumen such that the distal tube is disposed within the proximal tube lumen and the single solid loop structure extends distally of the distal end of the proximal tube, and (ii) the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the single solid loop structure; A method is provided which includes:

[0019] These and other objects and features of the present invention will be more fully disclosed or made clear by the following detailed description of preferred embodiments of the invention, which should be considered in conjunction with the accompanying drawings, in which like numerals refer to like parts and in which: [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of a novel braided construct used to form a novel snare. [Figure 2] 2 is a schematic cross-sectional view of one cross section of the braided structure of FIG. 1. [Figure 3] 2 is a schematic cross-sectional view of another cross section of the braided construct of FIG. 1. [Figure 4] 1 is a cross-sectional view of a novel composite filament formed in accordance with the present invention. [Figure 5] 1 is a schematic diagram of another novel braided construction formed in accordance with the present invention. [Figure 6]10 is a schematic diagram of yet another braided construction formed in accordance with the present invention, illustrating how the braided construction may be made into a novel snare formed in accordance with the present invention. FIG. [Figure 7] 1 is a schematic diagram of a novel snare formed in accordance with the present invention and attached to a catheter such that the guidewire lumen of the catheter is axially aligned with the guidewire lumen of the novel snare. [Figure 8] 1 is a schematic diagram of a novel braided construction formed in accordance with the present invention and illustrating how the braided construction may be made into a novel single loop snare formed in accordance with the present invention. [Figure 9] FIG. 9 is a schematic diagram showing further details of how the novel braided construction of FIG. 8 may be formed into a novel single loop snare formed in accordance with the present invention. [Figure 10] FIG. 10 is a schematic diagram of a single-loop snare formed from the novel braided construct of FIGS. 8 and 9 attached to a catheter such that the guidewire lumen of the catheter is axially aligned with the guidewire lumen of the novel snare. [Figure 11] FIG. 10 is a plan view of a novel single-loop snare formed from the novel braided construction of FIGS. 8 and 9 and attached to a novel catheter formed in accordance with the present invention, such that the lumen of the catheter is axially aligned with the guidewire lumen of the novel snare. [Figure 12] FIG. 10 is a schematic diagram of a single-loop snare formed from the novel braided construct of FIGS. 8 and 9 attached to a catheter such that the guidewire lumen of the catheter is axially aligned with the guidewire lumen of the novel snare, further showing an occlusive sheath with a radiopaque band disposed on the catheter and a guidewire passing through the snare. DETAILED DESCRIPTION OF THE INVENTION

[0021] Traditionally, braiding requires a minimum of three threads / filaments (collectively "filaments") of a particular material (e.g., fabric, metal wire, composite, etc.) intertwined in a specific pattern to form a single profile. Braiding may be used to form a solid three-dimensional object (e.g., a rod) or a hollow three-dimensional object (e.g., a tube). When forming a hollow three-dimensional object such as a tube, a core material is preferably used, with the braided construct braided around the core material to create a tubular braided construct. Braiding differs significantly from a cable or rope in that the intertwining of the threads / filaments is a key feature of the process.

[0022] Braids allow for great design / construction flexibility. By way of example and not limitation, hollow braided constructs may be created to allow selected segments of the braided construct to easily change diameter in response to an external force (e.g., increase in diameter radially as the construct is longitudinally contracted) or have variable diameters (e.g., multiple different radial diameters along the longitudinal dimension of the braided construct).

[0023] Solid braided constructions may be constructed to have excellent axial compliance while providing bending flexibility, properties that are unique to braided constructions and are not offered by cables, ropes, and coils.

[0024] Preferably, the present invention is formed using a new braiding technology, sometimes referred to hereinafter as "modified braiding." Prior to the introduction of the modified braiding machine, the braiding machine could construct hollow or solid core braids with various "ends" (i.e., number of filaments), "PIC" counts (i.e., density of braids per unit length), and braid angles (which, for tubular braids, specifies radial strength). The modified braiding machine allows for braided constructs with hollow or tubular segments, which then separate into smaller braided constructs (either tubular or solid segments) and then revert back to a single tubular segment. The modified braiding machine also allows for the selection of the number of ends, PIC count, and braid angle for the tubular section, with the added benefit of separating into multiple modified braid segments.

[0025] The number of segments in a braided construct is directly related to the number of ends the braider is configured to. By way of example and not limitation, in a 24 filament construct, the maximum number of segments that may be created is eight, since each segment requires three filaments to create the braid. Conversely, a modified braiding machine may be configured to have a single tubular section that is solid (i.e., non-tubular) and creates a single modified segment containing an equal number of filaments. A modified braid may be used to braid a single tube construct from all filaments used, which then transitions into multiple braided segments in a continuous operation (spool to spool) before transitioning back to a single braided tube construct, as described in more detail below.

[0026] The present invention involves the provision and use of a new and improved surgical snare that is manufactured as a braided tubular braid construction, the novel snare including a central lumen for receiving a guidewire.

[0027] More particularly, and now turning to FIG. 1, as will be explained in more detail below, the present invention includes the provision and use of a new and improved snare 5, as well as a novel method for forming the snare 5 from a braided construct formed using modified braiding.

[0028] The snare 5 generally comprises a braided construct 10 comprising a proximal tube 15, a distal tube 20, and a loop region 25 disposed between the proximal tube 15 and the distal tube 20. The braided construct 10 is formed as a unitary construct, i.e., the proximal tube 15, the loop region 25, and the distal tube 20 are integrally formed (i.e., braided) as a single braided construct comprising multiple filaments braided together to form a three-dimensional structure.

[0029] 2, the braided construct 10 is braided from a plurality of wires or filaments 30. The number of filaments 30 used to form the braided construct 10 typically ranges from 6 to 36 filaments (an even number of filaments is typically used), with each filament 30 having a diameter ranging from 25.4 micrometers (0.001 inches) to 203.2 micrometers (0.008 inches). In one preferred form of the invention, 24 filaments 30 are used to form the braided construct 10.

[0030] 2, a predetermined number of filaments 30 (e.g., 24 filaments) are braided together using the modified braiding process described above, thereby forming the proximal tube 15 in the form of a hollow braided structure defining a central proximal lumen 35 (FIG. 2).

[0031] 1 and 3, once the proximal tube 15 has been formed to have a desired length, the filaments 30 transition into a plurality of solid loop structures 40 at a proximal transition point 45. The solid loop structures 40 then extend distally a predetermined distance (selected according to the desired size loop (see below)) before each solid loop structure 40 transitions into the distal tube 20 at a distal transition point 50. Each solid loop structure 40 comprises a plurality of filaments 30 braided together to form the solid loop structure. By way of example and not limitation, when 24 filaments 30 are used to form the braided construct 10, each solid loop structure 40 may comprise eight braided filaments.

[0032] It will be appreciated that the number of solid loop structures 40 (and therefore the number of filaments 30 comprising the solid loop structures 40) may be varied as needed to create the desired number of loop structures 40, insofar as the number of solid loop structures 40 formed determines the number of loops ultimately comprised in the snare 5. By way of example and not limitation, if four loop structures are desired (i.e., thereby creating a snare 5 comprising four loops), each loop structure 40 would comprise six filaments 30. By way of further example and not limitation, if two loop structures are desired (i.e., thereby creating a snare 5 comprising two loops), each loop structure 40 would comprise twelve filaments 30. It will be appreciated, therefore, that the number of filaments 30 comprising each loop structure 40 is a function of the total number of filaments 30 utilized to form the braided construct 10 divided by the number of desired loop structures 40.

[0033] It is further understood that the length of each loop structure 40 determines the size (i.e., circumference) of the final loop formed from each loop structure 40. Thus, by controlling the distance each loop structure 40 is braided distally, the final size of the resulting loop may be controlled.

[0034] 1 , when moving distally a predetermined distance from the proximal transition point 45, each loop structure 40 transitions into the distal tube 20 at a distal transition point 50. As each of the loop structures 40 transitions into the distal tube 20 at the distal transition point 50, the filaments 30 comprising each of the loop structures 40 are braided together to form the sidewall of the distal tube 20, thereby defining a central distal lumen 55.

[0035] As will be understood, in one preferred form of the invention, when multiple filaments 30 are braided together to form the distal tube 20, an external compression sleeve 60 (FIG. 6) is used to radially constrict the distal tube 20 during braiding to form a distal tube 20 having a diameter slightly smaller than the diameter of the central proximal lumen 35 of the proximal tube 15, as will be explained in more detail below, thereby facilitating insertion of the distal tube 20 into the central proximal lumen 35 of the proximal tube 15.

[0036] Additionally, if desired, the braided structure 10 may be "shape-set" by thermally annealing (e.g., soft-annealing) the filaments 30 during or after braiding of the braided structure 10 to prevent the filaments 30 (and thus the braided structure 10) from unraveling. More particularly, if desired, a two-step thermal annealing process may be used to form the braided structure 10. In a first, "pre-annealing" thermal annealing step of the two-step thermal annealing process, the braided structure 10 may be thermally annealed to (i) prevent the filaments 30, including the proximal tube 15, the distal tube 20, and / or the loop region 25, from unraveling, and / or (ii) set the outer diameter of the proximal tube 15 and / or the distal tube 20 at the braided outer diameter, thereby forming the proximal tube 15 and / or the distal tube 20 having an outer diameter that matches the diameter of the core (not shown) around which the proximal tube 15 and / or the distal tube 20 are braided. As a result, when the assembled snare 5 is thermally annealed in its final form, the proximal tube 15 and / or the distal tube 20 "grasp" a mandrel having an outer diameter slightly larger than the diameter of the proximal tube 15 and / or the distal tube 20 when disposed within the central proximal lumen 35 and the central distal lumen 55, respectively, thereby maintaining the snare 5 relative to the mandrel during the final thermal annealing process.

[0037] It will also be appreciated that, if desired, one or more filaments 30 used to form the braided construct 10 may comprise a composite of multiple materials. By way of example and not limitation, and turning now to FIG. 4 , a composite filament 30 is shown comprising a core material 65 and an outer sheath 70. The core material 65 and / or outer sheath 70 may be selected for desired mechanical properties (e.g., column strength, flexibility, shape memory) and / or radiopacity (e.g., to facilitate visualization under fluoroscopy or other imaging modalities). By way of example and not limitation, one or more filaments 30 may be constructed with a nitinol outer sheath 70 and a noble metal (e.g., gold, platinum, iridium, etc.) core material 65. In this form of the invention, the noble metal core material 65 provides radiopacity, and the nitinol outer sheath 70 provides shape memory (or superelasticity). It will be appreciated that, if desired, the outer sheath 70 may be constructed from a radiopaque material and the core material 65 may be made from a non-radiopaque material.

[0038] It will also be appreciated that, if desired, the braided construct 10 may be formed from filaments 30 having different diameters within a range of 25.4 micrometers (0.001 inch) to 203.2 micrometers (0.008 inch). By way of example and not limitation, some of the filaments 30 used to form the braided construct 10 may have a diameter of 25.4 micrometers (0.001 inch), while others of the filaments used to form the braided construct 10 may have a diameter of 127 micrometers (0.005 inch). By way of further example and not limitation, some of the filaments 30 used to form the braided construct 10 may have a diameter of 25.4 micrometers (0.001 inch), others of the filaments 30 used to form the braided construct 10 may have a diameter of 127 micrometers (0.005 inch), and still others of the filaments 30 used to form the braided construct 10 may have a diameter of 203.2 micrometers (0.008 inch).

[0039] And, it will be appreciated that the braided construct 10 may be braided from a plurality of filaments 30 which are themselves formed from braided or cabled filaments.

[0040] It will be appreciated that the continuous (e.g., spool-to-spool) braiding process used to form the snare 5 may also be used to create multiple snares 5 from a single braided construct 10. To that end, in another form of the invention, the braided construct 10 is formed as a continuous series of tubes separated by loop regions. More particularly, and turning now to FIG. 5, in this form of the invention, the braided construct 10 comprises two or more loop regions 25 separated by one or more intermediate tubes 75. The intermediate tube 75 is braided from the filament 30 in the same manner as the distal tube 20; however, the filament 30 transitions to one or more solid loop structures 40a defining second loop regions 25a at a second proximal transition point 45a at the distal end of the intermediate tube 75 before transitioning to the distal tube 20 at a distal transition point 50a in the manner described above.

[0041] It will be appreciated that in this form of the invention, distal tube 20 may be replaced by a second intermediate tube 75a, which transitions at its distal end at a proximal transition point 45b to one or more solid loop structures 40b defining third loop region 25a, etc. Each intermediate tube 75 is characterized by a trim location 80 located approximately at the midpoint of each intermediate tube 75. As a result, in this form of the invention, braided construct 10 may be formed with proximal tube 15 at the proximal end, distal tube 20 at the distal end, multiple intermediate tubes 75, 75a, 75b, etc., and multiple loop regions 25, 25a, 25b, etc., disposed therebetween. The braided construct 10 may then be cut at trim regions 80 to form two or more braided constructs 10, which may then each be transformed into a snare 5, as described in more detail below. As discussed above with respect to the embodiment of FIG. 1, to facilitate forming the snare 5, a two-step thermal annealing process (or a three-step thermal annealing process) may be utilized to prevent the filament 30 from unraveling and / or to fix the outer diameter of one or more of the proximal tube 15, the distal tube 20, and / or the intermediate tube 75, as described in more detail below.

[0042] 6 , the snare 5 is formed from the braided construct 10 by inserting the distal end of the distal tube 20 into the central proximal lumen 35 of the proximal tube 15. More specifically, as described above, the distal tube 20 is preferably formed with a diameter slightly smaller than the diameter of the central proximal lumen 35 of the proximal tube 15 (e.g., by applying external compression from the compression sleeve 60 when forming the distal tube 20). To form the snare 5, the distal tube 20 is passed through the gap 85 between two adjacent solid loop structures 40 of the loop region 25 and enters the distal end of the central proximal lumen 35 of the proximal tube 15. Because the distal tube 20 has a diameter only slightly smaller than the diameter of the central proximal lumen 35 of the proximal tube 15, the sidewalls of the distal tube 20 are pressed against the inner surface of the sidewalls of the proximal tube 15 without substantially any gap therebetween, such that the central distal lumen 55 of the distal tube 20 remains open. If the proximal tube 15 and the distal tube 20 are constructed to have the same longitudinal dimension, the distal end of the distal tube 20 is preferably disposed intermediate the proximal and distal ends of the proximal tube 15 when the snare 5 is formed from the braided construct 10 in the manner described above. In one preferred form of the invention, the distal end of the distal tube 20 is located within the central proximal lumen 35 at a location midway between the proximal and distal ends of the proximal tube 15. It will be appreciated that, if desired, the distal tube 20 may be formed to have a length approximately half the length of the distance between the proximal and distal ends of the proximal tube 15.

[0043] To facilitate insertion of the distal tube 20 into the central proximal lumen 35 of the proximal tube 15, (i) the proximal tube 15 may be formed over a mandrel (not shown) disposed over all (or a portion) of the central proximal lumen 35, and / or (ii) the distal tube 20 may be formed over a second mandrel (not shown) disposed over all (or a portion) of the central lumen 55 of the distal tube 20. Thermally annealing (e.g., pre-annealing) the braided construct 10 prior to inserting the distal tube 20 into the central proximal lumen 35 of the proximal tube 15 serves to fix the outer diameter of the proximal tube 15 and / or the distal tube 20 so that the proximal tube 15 and / or the distal tube 20 grip a mandrel disposed within the central proximal lumen 35 and / or the central distal lumen 55, thereby greatly facilitating insertion of the distal tube 20 into the central proximal lumen 35 of the proximal tube 15 in the manner described above.

[0044] It will be appreciated that this pre-annealing step is separate from the final thermal annealing step that is performed once the braided construct 10 is formed into the snare 5. That is, the final thermal annealing step sets (i.e., fixes) the geometry of the filament 30 into the configuration of the final desired structure (e.g., snare 5), whereas the "pre-annealing" thermal annealing step is utilized to change the physical properties of the braided construct 10 to facilitate insertion of the distal tube 20 into the central proximal lumen 35 of the proximal tube 15 in the manner described above.

[0045] 7, when distal tube 20 is inserted into proximal tube 15 in the manner described above, each solid loop structure 40 is transformed into a snare loop 90, with central distal lumen 55 extending completely through combined proximal and distal tubes 15, 20 to define proximal and distal openings 95, 100. More specifically, solid loop structures 40 in loop region 25 are shape-set by thermal annealing to form snare loops 90 of preferably equal length, equally radially spaced apart, and preferably extending at an angle of 15° to 90° relative to the central axis of central distal lumen 55, thereby forming a multi-loop snare 5 having central distal lumen 55 extending therethrough to serve as a guidewire lumen, as described in more detail below.

[0046] 7, if desired, the snare 5 may be attached to the distal end of a single or multiple lumen catheter 105 (or other tube) such that the central lumen 110 of the catheter 105 is axially aligned with the central distal lumen 55 of the snare 5, thereby allowing the snare 5 and catheter 105 to pass over the guidewire G as it extends from the distal opening 100 of the snare 5 (FIG. 7). It will be appreciated that, insofar as the distal tube 20 preferably extends into the central proximal lumen 35 of the proximal tube 15 approximately half the distance between the distal and proximal ends of the proximal tube 15 (i.e., the distal tube 20 thereby occupies the portion of the central proximal lumen 35 extending from the center point of the central proximal lumen 35 to its distal end), the proximal portion of the central proximal lumen 35 is open to receive the distal end of the catheter 105 for attachment of the catheter 105 to the snare 5, as will be described in more detail below.

[0047] 8-10, in another embodiment of the present invention, the plurality of loop structures 40 of the loop region 25 are twisted together to form a single interdigitated loop structure 115 (FIG. 9) disposed between the proximal tube 15 section and the distal tube 20. More specifically, the proximal tube 15 and the distal tube 20 are rotated in opposite directions (and / or one of the proximal tube 15 and the distal tube 20 is rotated while the other of the proximal tube 15 and the distal tube 20 is held stationary), thereby twisting the solid loop structures 40 together and thereby forming the interdigitated loop structure 115. The solid loop structure 40 is twisted together and shape-set by thermal annealing to form a single snare loop 120 extending at 15° to 90° relative to the central longitudinal axis of the central distal lumen 55. Thereafter, when the distal end of the distal tube 20 section is inserted into the distal end of the central proximal lumen 35 of the proximal tube 15 (see above), the single snare loop 120 extends distally beyond the distal end of the proximal tube 15, and the central distal lumen 55 extends through the snare 5 such that a guidewire G can pass through the central distal lumen, exit the distal opening 100, and distally beyond the snare loop 120. It will be appreciated that the embodiment of Figures 8-10 may be subjected to a pre-annealing thermal annealing step prior to inserting the distal tube 20 into the central proximal lumen 35 in the same manner as described above in connection with the embodiment of Figures 1, 5, and 6 to facilitate formation of the snare 5. For the embodiment of Figures 8-10, preferably, the pre-annealing step is performed before the single snare loop 120 is formed by twisting the solid loop structure 40 together, as described above.

[0048] It will be further understood that the structural characteristics of a single snare loop 120 may be controlled by varying the crossover location and timing of the braiding of the loop structure 40 from the filament 30, as will be apparent to those skilled in the art in view of the present disclosure.

[0049] The snare 5 with the single snare loop 120 may then be attached to a single or multi-lumen catheter 105 in the manner described above. The lumen 110 of the catheter 105 is axially aligned with the central distal lumen 55 of the distal tube 20 so as to provide a pathway for the guidewire G (or to provide a pathway for the passage of other medical devices and / or agents, e.g., injectable substances).

[0050] It will be appreciated that, if desired, the snare 5 may be attached to a solid shaft rather than a single or multi-lumen catheter.

[0051] 11 , in another embodiment of the present invention, snare 5 may be attached to the distal end of catheter 125. Catheter 125 is generally similar to catheter 105 described above, except that for catheter 125, the central lumen of the catheter does not extend the entire length of the catheter. More specifically, catheter 125 is formed with a guidewire lumen 130 that opens at the distal end of catheter 125 and extends proximally to a location distal to the proximal end of catheter 125. Port 135 penetrates the side wall of catheter 125 and opens at guidewire lumen 130, thereby providing a “rapid-exchange” side port for receiving a guidewire G.

[0052] As will be apparent to those skilled in the art in view of the present disclosure, it will be appreciated that when the snare 5 is attached to the distal end of a catheter (e.g., catheter 105, catheter 125, etc.), a second braided construction (not shown) may be disposed within the central lumen (e.g., central lumen 110) of the catheter, thereby providing increased strength to facilitate movement of the catheter and snare 5 through tortuous paths (e.g., the patient's vasculature). Optionally, thermal bonding may be utilized to fuse the second braided construction disposed within the central lumen of the catheter to the proximal tubing 15 and / or distal tubing 20 disposed within the central proximal lumen 35 of the proximal tubing 15, thereby securely attaching the snare 5 to the distal end of the catheter.

[0053] 12 , it will also be appreciated that, if desired, the closure sheath 140 may extend over the catheter 105 (or catheter 125) to allow an object to be captured by the single snare loop 120 (or snare loop 90), retracted proximally relative to the closure sheath 140, and captured between the single snare loop 120 (or snare loop 90) and the distal end of the closure sheath 140. More particularly, in this form of the invention, the closure sheath 140 generally comprises a distal end, a proximal end, and a lumen 145 extending therebetween. The lumen 145 is sized to slidably receive the catheter 105 (or catheter 125) therein, thereby allowing the closure sheath 140 to move distally / proximally relative to the snare loop 120 (or snare loop 90) (or allow the snare 5 to be moved proximally / distally relative to the closure sheath 140). Preferably, the closure sheath 140 includes a radiopaque band 145 disposed near the distal end of the closure sheath 140, thereby allowing the surgeon to visualize the distal end of the closure sheath 140 under image guidance (e.g., fluoroscopy) during the surgical procedure.

[0054] (Variations of the Preferred Embodiment) It will be understood that many additional changes in the details, materials, steps, and arrangements of parts described and illustrated herein to explain the principles of the invention may be made by those skilled in the art while still remaining within the principles and scope of the invention.

Claims

1. 1. A method of forming a surgical snare, comprising: providing a plurality of filaments; braiding the plurality of filaments together to form a braided tubular construction, the braided tubular construction comprising: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube, the loop region comprising at least one loop structure, the at least one loop structure comprising at least three of the plurality of filaments braided together; braiding, (i) the distal tube is disposed within the proximal tube lumen such that the at least one loop structure extends distally of the distal end of the proximal tube in the form of at least one loop; and (ii) inserting the distal end of the distal tube into the open distal end of the proximal tube and into the proximal tube lumen such that the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the at least one loop; A method comprising:

2. The method of claim 1 , wherein the proximal tube lumen comprises a first radius and the distal tube comprises a second radius, the second radius being less than the first radius.

3. The method of claim 1 , wherein as the braided tubular construct is being braided, an external compression sleeve is applied to the distal tube to radially constrict the distal tube during braiding.

4. the at least one loop structure includes a plurality of solid loop structures; 2. The method of claim 1, wherein prior to inserting the distal end of the distal tube into the proximal tube lumen, at least one of the proximal tube and the distal tube is rotated relative to the other of the proximal tube and the distal tube about a central longitudinal axis of the distal tube such that the multiple solid loop structures are twisted together to form a single solid loop structure.

5. The method of claim 1 , wherein the braided construct is heat annealed after braiding to prevent the plurality of filaments from unraveling.

6. Each of the plurality of filaments is a composite structure, A core material; an outer sheath covering the core material; The method of claim 1 , comprising a composite structure comprising:

7. The method of claim 6 , wherein at least one of the core material and the outer sheath comprises a radiopaque material.

8. The method of claim 7 , wherein the core material comprises a precious metal and the outer sheath comprises a shape memory alloy.

9. The method of claim 8 , wherein the shape memory alloy comprises nitinol and the core material comprises one selected from the group consisting of gold, platinum, and iridium.

10. 10. The method of claim 1, wherein each of the plurality of filaments has a diameter of from 25.4 micrometers (0.001 inch) to 203.2 micrometers (0.008 inch).

11. The method of claim 1 , wherein each of the plurality of filaments is formed from a braided or cabled filament.

12. The method of claim 1 , wherein each of the plurality of loops extends at an angle of between 15 degrees and 90 degrees relative to the longitudinal axis of the distal tube lumen.

13. 1. A surgical snare comprising a braided tubular construction formed by braiding together a plurality of filaments, The braided tubular structure comprises: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube; the loop region comprises a plurality of solid loop structures, each of the plurality of solid loop structures comprising at least three of the plurality of filaments braided together; The distal end of the distal tube is inserted into the open distal end of the proximal tube and into the proximal tube lumen so that (i) the distal tube is disposed within the proximal tube lumen and the plurality of solid loop structures extend distal to the distal end of the proximal tube in the form of a plurality of loops, and (ii) the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the plurality of loops.

14. 14. The surgical snare of claim 13, wherein the surgical snare includes a single loop formed by rotating at least one of the proximal and distal tubes relative to the other of the proximal and distal tubes about a central longitudinal axis of the distal tube before the distal tube is inserted into the proximal tube lumen.

15. The surgical snare of claim 13 , wherein the braided construction is heat annealed after braiding to prevent the plurality of filaments from unraveling.

16. Each of the plurality of filaments is a composite structure, A core material; an outer sheath covering the core material; 14. The surgical snare of claim 13, comprising a composite structure comprising:

17. The surgical snare of claim 16, wherein at least one of the core material and the outer sheath comprises a radiopaque material.

18. The surgical snare of claim 17, wherein the core material comprises a precious metal and the outer sheath comprises a shape memory alloy.

19. The surgical snare of claim 18, wherein the shape memory alloy comprises nitinol and the core material comprises one selected from the group consisting of gold, platinum, and iridium.

20. The surgical snare of claim 13, wherein each of the plurality of filaments has a diameter of from 25.4 micrometers (0.001 inch) to 203.2 micrometers (0.008 inch).

21. The surgical snare of claim 13 , wherein each of the plurality of filaments is formed from a braided or cabled filament.

22. The surgical snare of claim 13 , wherein each of the plurality of loops extends at an angle of between 15 and 90 degrees relative to a longitudinal axis of the distal tube lumen.

23. A catheter having a distal end, a proximal end, and a sidewall extending therebetween, said sidewall defining a central catheter lumen. Furthermore, the open proximal end of the proximal tube is attached to the distal end of the catheter such that the central catheter lumen is axially aligned with the distal tube lumen, and further, the central catheter lumen and the distal tube lumen are sized to receive a guidewire therein.

14. The surgical snare of claim 13.

24. 24. The surgical snare of claim 23, wherein the catheter includes a port formed in the sidewall of the catheter intermediate the distal and proximal ends of the catheter, the port opening onto the central catheter lumen and sized to receive a guidewire therein.

25. a closure sheath having a distal end, a proximal end, and a closure sheath lumen extending therebetween; 24. The surgical snare of claim 23, wherein the closed sheath lumen is sized to fit over the catheter so as to be slidably movable relative thereto.

26. 26. The surgical snare of claim 25, wherein the closure sheath comprises at least one radiopaque band disposed on an outer surface of the closure sheath.

27. 1. A method of forming a surgical snare, comprising: providing 24 filaments; braiding the 24 filaments together to form a braided tubular construction, the braided tubular construction comprising: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and braiding a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube, the loop region comprising three solid loop structures, each of the three solid loop structures comprising eight filaments braided together; radially constraining the distal tube during braiding of the distal tube such that the distal tube has a radius smaller than a radius of the distal tube lumen; (i) inserting the distal end of the distal tube into the open distal end of the proximal tube and into the proximal tube lumen such that the distal tube is disposed within the proximal tube lumen and the three solid loop structures extend distally of the distal end of the proximal tube in the form of three loops; and (ii) the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the three loops; A method comprising:

28. 1. A method of forming a surgical snare, comprising: providing a plurality of filaments; braiding the plurality of filaments together to form a braided tubular construction, the braided tubular construction comprising: a proximal tube having an open proximal end, an open distal end, and a proximal tube lumen extending therebetween; a distal tube having an open proximal end, an open distal end, and a distal tube lumen extending therebetween; and braiding, comprising a loop region disposed between the distal end of the proximal tube and the proximal end of the distal tube, the loop region comprising a plurality of solid loop structures, each of the plurality of solid loop structures comprising at least three of the plurality of filaments braided together; rotating at least one of the proximal tube and the distal tube relative to the other of the proximal tube and the distal tube about a central longitudinal axis of the distal tube such that the plurality of solid loop structures are twisted together to form a single solid loop structure; (i) inserting the distal end of the distal tube into the open distal end of the proximal tube and into the proximal tube lumen such that the distal tube is disposed within the proximal tube lumen and the single solid loop structure extends distally of the distal end of the proximal tube, and (ii) the distal tube lumen extends from a point distal to the proximal end of the proximal tube to the single solid loop structure; A method comprising:

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