TISSUE RESECTION SNARES

Abstract

A tissue resection device for resecting tissue from a target site within a patient's body. The device includes an elongate shaft having a proximal end and a distal end. An actuation member extends partially through the shaft, and reciprocates within the shaft between a retracted position and an extended position. Multiple snare wires extend through the actuation member, and emerge outwards from a distal portion of the actuation member. The snare wires cooperate and join to form a snare loop, which engages the tissue intended to be resected. The snare loop is configured to enhance friction while engaging the tissue, to resect the tissue.

Claims

1. A tissue resection device comprising: an elongate shaft having a proximal end and a distal end; an actuation member extending at least partially through the elongate shaft, and being configured to reciprocate within the shaft between a retracted position and an extended position; one or more snare wires extending through a lumen of the actuation member and emerging outwards from a distal portion of the actuation member; and a snare loop formed by the one or more snare wires, the snare loop being configured to engage tissue intended to be resected from a target site, and further comprising a plurality of elements positioned over a peripheral surface of the snare loop, the elements being configured to increase friction between the tissue and the snare loop.

2. The tissue resection device of claim 1, wherein reciprocation of the actuation member moves the snare loop between an expanded orientation and a retracted position within the elongate shaft, and wherein, in the extended position of the actuation member, the snare loop is in the expanded orientation, and in the retracted position of the actuation member, the snare loop retracts into the elongate shaft.

3. The tissue resection device of claim 1, wherein the one or more snare wires have a flattened, rectangular cross-section, and a portion of each of the snare wires is anchored to an interior portion of the actuation member, wherein the interior portion of the actuation member includes a surface corresponding to the cross-section of the one or more snare wires to maintain the orientation of the snare wires with respect to the tissue.

4. A tissue resection device of claim 1, wherein the snare loop has one of a plurality of grooves, striations, indentations, protrusions, and depressions provided over a peripheral portion thereof, the grooves, the striations, the indentations, the protrusions, or the depressions extending at least partially over the length of the snare loop, to enhance friction during engagement of the snare loop with the tissue.

5. A tissue resection device of claim 1, wherein the snare loop has an irregular rough surface, configured to enhance its engagement with the tissue.

6. A tissue resection device of claim 2, wherein, in the expanded orientation, the snare loop has one of an elliptical, a circular, an ovular, a square, a rectangular, a polygonal and an irregular shape, overlaying the tissue.

7. A tissue resection device of claim 1, wherein in the expanded orientation of the snare loop, the snare wires orient substantially perpendicular to a plane containing the tissue, and a distal portion of each of the snare wires is anchored to an interior portion of the actuation member.

8. A tissue resection device of claim 7, wherein each of the plurality of elements is a traction ring engaging and at least partially enclosing the snare loop's cross-sectional surface, and having an irregular surface configured to engage the tissue, the irregular surface being configured to increase friction between the snare loop and the tissue, for resection of the tissue.

9. A tissue resection device of claim 8, wherein each of the traction rings is a C-shaped ring having an open-ended structure.

10. A tissue resection device of claim 8, wherein the traction rings are one of snap-fitted, press-fitted and crimped to the snare loop, and have a slanting and decreasing cross-sectional rear structure, to facilitate smooth retraction of the snare loop into the actuation member.

11. A tissue resection device of claim 1, further comprising, a substantially helical structure extending across and coiled around the snare loop, the helical structure having its extreme ends anchored to the distal end of the elongate shaft, and being configured to grasp portions of the tissue between the turns thereof.

12. A tissue resection device of claim 11, wherein the adjacent turns of the helical structure are movable with respect to each other, to alter the pitch of the helical structure in response to a transition of the snare loop between an expanded orientation and a retracted position within the elongate shaft.

13. A tissue resection device of claim 12, further comprising an actuation element coupled to the helical structure, the actuation element being configured to independently reduce the spacing between the adjacent turns of the helical structure, to facilitate grasping of the portions of the tissue between the adjacent turns.

14. The tissue resection device of claim 1, further comprising an auxiliary loop provided at a peripheral portion of the snare loop, the auxiliary loop being configured to engage and resect a portion of the tissue intended to be resected, and being further configured to increase frictional engagement of the snare loop with the tissue,

15. The tissue resection device of claim 14, wherein the auxiliary loop is provided at a distal peripheral portion of the snare loop, and is configured to engage the tissue independent of the engagement of the snare loop with the tissue.

16. A tissue resection device comprising: an elongate shaft having a proximal end and a distal end; an actuation member extending at least partially through the elongate shaft, and being configured to reciprocate within the shaft between a retracted position and an extended position; and one or more snare wires extending through a lumen of the actuation member, emerging out from a distal portion of the actuation member, and having a flattened, rectangular cross-section, such that the snare wires orient substantially perpendicular o a plane containing tissue to be resected; wherein the interior portion of the actuation member includes a surface corresponding to the cross-section of the one or more snare wires to maintain the orientation of the snare wires with respect to the tissue.

17. The tissue resection device of claim 1, wherein reciprocation of the actuation member moves the snare wires between an expanded orientation and a retracted position within the elongate shaft, and wherein, in the extended position of the actuation member, the snare wires are in the expanded orientation, and in the retracted position of the actuation member, the snare wires retract into the elongate shaft.

18. A tissue resection device of claim 1, wherein the snare wires have one of a plurality of grooves, striations, indentations, protrusions, and depression provided over a peripheral portion thereof, the grooves, the striations, the indentations, the protrusions, or the depressions, extending at least partially over the length of the snare loop, to enhance friction during engagement of the snare wires with the tissue.

19. A tissue resection device comprising: an elongate shaft having a proximal end and a distal end; an actuation member extending at least partially through the elongate shaft, and being configured to reciprocate within the shaft between a retracted position and an extended position; and a snare loop formed by one or more snare wires extending through a lumen of the actuation member, the snare loop being configured to engage tissue intended to be resected from a target site, wherein the snare loop includes a plurality of pinching structures positioned around different peripheral positions of the snare loop, configured to engage the tissue at locations of the pinching structures.

20. The tissue resection device of claim 19, wherein the snare loop includes one or more snare wires having a flattened, rectangular cross-section, and a portion of each of the snare wires is anchored to an interior portion of the actuation member, wherein the interior portion of the actuation member includes a surface corresponding to the cross-section of the one or more snare wires to maintain the orientation of the snare wires with respect to the tissue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in, and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0018] FIGS. 1A-1C illustrate various perspective views of a medical device for resecting tissue in accordance with an embodiment of the present disclosure.

[0019] FIG. 2 is a perspective view of a medical device, according to another embodiment of the present disclosure.

[0020] FIGS. 3A-3D illustrate various perspective views of a medical device for resecting tissue, in accordance with another embodiment of the present disclosure.

[0021] FIGS. 3E and 3F show perspective views of a medical device, according to another embodiment of the present disclosure.

[0022] FIGS. 4A-4C illustrate various perspective views of a medical device for resecting tissue from a target site within a patient's body, in accordance with another embodiment of the present disclosure.

[0023] FIG. 5 shows a perspective view of a medical device for resecting tissue, in accordance with another embodiment of the disclosure.

[0024] FIG. 6 shows cross-sectional views of exemplary keying mechanisms for orienting a snare loop, in accordance with another embodiment of the disclosure.

[0025] FIG. 7 shows a perspective view of a medical device for resecting tissue, in accordance with another embodiment of the disclosure.

[0026] FIG. 8 shows a perspective view of a medical device for resecting tissue, in accordance with another embodiment of the disclosure.

DESCRIPTION OF THE EMBODIMENTS

[0027] Reference will now be made in detail to embodiments of the present disclosure, examples of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0028] Embodiments of the present disclosure may relate to devices used in medical procedures like Endoscopic Mucosal Resection (EMR), Endoscopic Submucosal Dissection (ESD), polypectomy and mucosectomy, etc. More particularly, embodiments of the present disclosure are directed to medical procedures using snares to ensnare tissue from a target site within a patient's body, where the engagement of a snare loop while being associated with the tissue is enhanced by suitable structures cooperating with each other, when the medical device is operated. The medical device may include an elongate shaft having a proximal end and a distal end. An actuation member may extend partially through the elongate shaft, and may reciprocate (i.e., move back and forth) through the shaft. A proximal end of the elongate shaft may be operably connected to an actuating mechanism, and a distal end may be operably coupled to a suitable end-effector. The end-effector may be a snare loop, which may be controlled and manipulated by an operator/surgeon/physician, using the actuating mechanism at the proximal end of the elongate shaft, while performing the medical procedure. The end-effector engages the tissue intended to be resected through suitable structures cooperating with each other, to enhance friction and to facilitate smooth resecting, during the engagement of the snare loop with the tissue. The integral components of medical device of the present disclosure will be explained in further details hereinafter, in conjunction with the figures to follow.

[0029] As part of the disclosure, mechanisms may facilitate the connection and disconnection of snare loops having different appropriate structures, to the distal portion of the medical device, as will be explained through different embodiments of the present disclosure hereinafter.

[0030] Various shapes of the end-effector can be utilized for the snare loop, for example, these can be circular, elliptical, ovular, polygonal, and irregular in shape, etc., while engaging the tissue, and such shapes are intended to be within the scope of the present disclosure. Various configurations of the medical device's articulation, structure, and function are described in the embodiments of the disclosure. Further, wherever used in the disclosure, distal generally refers to a position or direction away from a user (i.e., the surgeon, physician, etc.), and proximal generally refers to a position or direction opposite the distal direction, and hence, closer to the user (i.e., towards the user).

EXEMPLARY EMBODIMENTS

[0031] FIGS. 1A-1C show different perspective views of a medical device for resecting tissue from a target site within a patient's body, in accordance with an embodiment of the present disclosure.

[0032] As shown in FIG. 1A, a medical device 100 may include an elongate shaft 102, having a proximal end 102 (a) and a distal end 102 (b). The elongate shaft 102 may be inserted into a lumen of a patient's body, to access a target site whereon a medical procedure is intended to be performed. The proximal end 102 (a) may be connected to a suitable actuation mechanism (not shown), for operating the medical device. The actuating mechanism may be any appropriate mechanism for controlling and operating the components of the medical device 100, to enable resection of tissue using the medical device. In an embodiment, the actuating mechanism may be a handle, configured to be driven either manually, or through a pneumatic, hydraulic or an electromechanical mechanisms.

[0033] An actuation member 106 may extend partially through the elongate shaft 102, and further, may extend outwards from the distal end 102 (b) of the elongate shaft. The actuation member 106 may reciprocate through or within a lumen of the shaft 102, between a retracted position and a fully extended position. While being in the fully extended position, a distal portion of the actuation member 106 may extend out from the distal end 102 (b). In the retracted position, the actuation member 106 may be capable of being fully retracted and contained within the shaft 102. Further, the reciprocation of the actuation member 106 through the shaft 102 may be facilitated through the actuating mechanism provided at a proximal portion of the medical device, as aforementioned.

[0034] Though currently shown as being of a semi-circular cross-section, the actuation member 106 may also be of any other suitable cross-section/structure, e.g., a polygonal, regular or irregularstructure, etc. Further, the shape of the elongate shaft 102 may change depending on the shape of the actuation member 106, to facilitate accommodation of the actuation member 106 into the shaft 102. Various other mechanisms may be used to urge snare wires 110 into an orientation that causes desired orientation of snare loop 118. That is, although FIGS. 1A and 1B depict actuation member 106 as being semi-circular and radially-orienting relative to a similarly shaped aperture of shaft 102, any other shape may be used. For example, FIG. 6 depicts other exemplary cross-sectional shapes of an actuation member, such as one having a key 602, a rectangle 604, two or more separated rectangles 606, a semi-circle 608, and/or two opposed flat faces 610. Thus, snare wires 110, actuation element 106, and shaft 102 may share any desired regular or irregular cross-sectional shape that urges them into a desired radial orientation relative to each other. In one embodiment, as shown in FIG. 7, a shaft 102 and/or actuation member 106 may each include one or more slits 702, 704, which allow snare wires 706 to extend through the slits and control radial orientation of the snare wires. In yet another embodiment, as shown in FIG. 8, a tapered lock 804 may be disposed over a shaft 802, such as at or around an interface between shaft 802 and snare wires 806. Tapered lock 804 may be shaped, for example to include an angled or tapered inner aperture, such that movement of the tapered lock 804 in distal direction causes snare wires 806 to be pressed together, to resist rotation, and/or to be oriented in a desired radial orientation. In one embodiment, an inner lumen of a tapered lock 804 may include any of the cross-sectional features described with respect to FIG. 6.

[0035] Multiple snare wires 110 may be provided to pass through the actuation member 106, and may extend out distally, to form a snare loop 118. Specifically the distal ends of the snare wires 110 may cooperate to join, and form the snare loop 118, As shown, the snare wires 110 may have a flattened shape, with a generally rectangular cross-section. When these snare wires cooperate to form the snare loop 118, they may orient themselves substantially perpendicular to the plane of the layer of tissue that the snare loop 118 engages with. Further, a proximal end of each of the snare wires 110 may be anchored to an interior portion of the actuation member 106. Any suitable mechanisms may be used to secure the proximal ends of the snare wires 110, including sealing or adhesively bonding the proximal ends to the interior portion of the actuation member 106. When anchored at their proximal ends to the interior portion of the actuation member 106, the snare wires 110 may be maintained in a fixed orientation relative to the layer of tissue, which may prevent these wires from rotating, due to any torsional forces developing therein. The actuation member 106 may act as an anti-torsion element for the snare wires 110. Further, since the snare wires remain in a relatively constant plane, the frictional engagement of the snare loop 118 with the tissue can be enhanced, and this mitigates the tendency of the snare loop 118 to slip off the target site.

[0036] To allow passage of the snare wires 110 through the actuation member 106, one or more openings 114 may be provided at a distal end of the actuation member 106, as shown. The size of such openings may depend on the dimensions of the snare wires 110. In an embodiment, the openings 114 may be designed to have an aperture that may assist in increasing vertical stiffness of the snare wires 110, while they pass through the openings, and eventually, engage the tissue. Specifically, the openings 114 may have a cross-section small enough to prevent the snare wires 110 from rotating therein, while passing through, and this may further ensure that the plane of orientation of the snare loop 118, while engaging the tissue remains substantially constant. This provides a high stiffness to the snare wires 110 while they engage the tissue, and may substantially reduce the tendency of the snare loop 118 to slip off from the tissue layer.

[0037] It is contemplated that a single snare wire 110 may be provided to pass through the actuation member 106, and extend outwards, to form the snare loop 118. That wire may have a similar structure, i.e., a flattened surface with a rectangular cross-section, and while engaging the tissue, the wire may orient itself substantially perpendicular to the plane of the tissue. Further, the ends of that wire may be anchored to an interior portion of the actuation member 106, to prevent the wire from rotating and changing its orientation while engaging the tissue.

[0038] To facilitate resection of the tissue through the snare loop 118, the actuation mechanism disposed at a proximal portion of the medical device 100, may be used to control the snare wires 110, and hence, the snare loop 118. Once the intended tissue has been resected, the snare loop 118 can be collapsed by retracting the snare wires 110 into the actuation member 106, to completely remove the resected tissue. In an embodiment, with the movement of the actuation member 106 distally, along the longitudinal axis of the elongate shaft 102, the snare wires 110 may simultaneously move in response, and this may affect the transition of the snare loop from its retracted position within the elongate shaft 102, into an expanded orientation. In a fully extended position of the actuation member 106 and the snare wires 110, in the direction outwards and away from the elongate shaft 102, the snare wires 110 may be completely drawn outwards, bringing the snare loop 118 into the expanded orientation. Further, in a similar manner, movement of the actuation member 106 and the snare wires 110 proximally, into the elongate shaft 102, may retract the snare wires 110 into the elongate shaft 102, and thus, may bring the snare loop 118 into its retracted position within the elongate shaft. Further, as mentioned earlier, the reciprocation of the actuation member 106 through the lumen of the elongate shaft 102 may be controlled through the actuation mechanism (not shown), disposed at the proximal portion of the medical device 100.

[0039] FIG. 1B shows a perspective partial view of the medical device 100, with the snare wires 110 extending outwards from the actuation member 106, and the actuation member 106 extending out from the elongate shaft 102, in an extended position.

[0040] FIG. 1C shows another perspective view of the medical device 100 of the present disclosure, where the snare loop 118 is in an expanded orientation, and is ready to engage the tissue intended to be resected. As shown, in this configuration, the actuation member 106 is retracted inward into the elongate shaft 102. It is contemplated that the elongate shaft 102 may have a sufficient longitudinal length to completely accommodate the actuation member 106 in its retracted position.

[0041] The actuation member 106 may be made of a conductive material, to allow passage of electric current through it, and for adapting it to serve as an electrical path for cautery cutting of the resected tissue. The actuation member 106 may be made of any suitable conductive material, including a metallic conductor, for example, aluminum, copper, etc., or a suitable conductive metallic alloy. A suitable current supplying source may transfer electric charge through the actuation member 106, to establish a flow of current through the actuation member 106. The current may be transferred to the snare loop 118, through the snare wires 110, to facilitate hot cautery cutting of the tissue resected by the snare loop 118.

[0042] FIG. 2 shows a perspective view of a medical device 200 for resecting tissue, from a target site within a patient's body, according to another embodiment of the present disclosure. As shown, a set of snare wires 210 may extend outward from the elongate shaft 202, to form a snare loop 218 configured to overlay and engage tissue. The method or mechanism for extending the snare wires 210 outward from the actuation member (though not shown herein); the provisions for incorporating the snare wires and retracting them into the actuation member; and the mechanism for facilitating reciprocation of the actuation member through the elongate shaft 202 may be similar to those described above in conjunction with FIG. 1A-1C. Hence, these will not be described in detail herein, to avoid unnecessary repetition.

[0043] The snare wires 210 may have any suitable cross-section, including a round, or an ovular cross-section. In the illustrated embodiment, the snare wires 210 may be designed to substantially increase the gripping potential of the snare loop 218, on engagement with the tissue. This is achieved by providing suitable structural modifications around the outer surface of the snare wires 210, in order to increase traction between the snare wires 210 and the tissue. Specifically, a gripping surface geometry for the snare loop 218 may be achieved by providing structural surface modifications 222, over portions of the snare wires 210 constituting the snare loop 218. The modifications 222 may be striations, knurls, grooves or indentations extending either partially across the peripheral surface of the snare loop 218, or extending across the entire length of the snare loop 218. Further, the modifications 222 may also be in the form of protrusions extending over the peripheral surface of the snare loop 218, to increase traction or friction between the snare loop 218 and the underlying tissue. Provision of the modifications 222 may substantially increase the gripping capacity of the snare loop 218 over the tissue, and ease pinching of the tissue during resection. The snare loop 218 may also have an irregular surface pattern.

[0044] FIGS. 3A-3D illustrate a medical device for resecting tissue according to another embodiment of the present disclosure.

[0045] As shown in FIG. 3A, a medical device 302 includes an elongate shaft 300 having an actuation member 306 contained therein, which reciprocates through the shaft 302 between a fully extended position and a retracted position. Multiple snare wires may cooperate to form a snare loop 318, which engages with an underlying tissue intended to be resected. In the illustrated embodiment, a substantially helical structure 326 may surround the snare loop 318, and may extend across the entire length of the snare loop 318. However, the helical structure 326 may also only partially cover the length of the snare loop 318. The structure 326 may be formed by one or more different wire springs 330 coiled around the snare loop 318, and joined to form a partial or continuous helix. The wire springs 330 may be spaced apart appropriately, defining a pitch for the helical structure 326, and this pitch may change when the snare loop 318 stretches or contracts, due to movement of the actuation member 306 residing partially within the elongate shaft 302. Specifically, when the snare loop 318 is in a fully expanded orientation over the tissue, the spacing between the wire springs 330 may be maximized. When the snare loop 318 is retracted inwards, into the actuation member 306, the spacing between the wire springs 330 (i.e., the pitch of the helical structure 330) may decrease in response to retraction, and the adjacently placed wire springs 326 may pinch the underlying tissue by moving closer to each other. Arranging the wire springs 330 over the snare loop 318, to create the substantially helical structure 326, also may prevent slippage of the snare loop 318 over the underlying tissue. The wire springs 330 may have an outer surface sufficiently rough, i.e., to increase traction, while engaging the tissue, thus, avoiding slippage. It is contemplated that the substantial helical structure 326 may include a wrapped or coiled wire that has an irregular and/or varying pitch between the coils.

[0046] FIG. 3B shows the medical device 300, with the helical structure 326 being in a compressed state, due to partial retraction of the snare loop 318 into the actuation member residing in the elongate shaft 302. As compared to the arrangement shown in FIG. 3A, the wire springs 330 may be more closely spaced, and are capable of pinching the underlying tissue along different portions. To facilitate compression of the wire springs 330, they may be made of any suitable conventional flexible material.

[0047] FIGS. 3C & 3D are partial views showing the wire springs 330 coiled around the snare loop 318. Specifically, FIG. 3C and FIG. 3D show an exemplary decrease in the pitch of the helical structure 326, due to compression of the wire springs 330.

[0048] FIG. 3E illustrates another embodiment where a pinching mechanism may be provided across the length of the snare loop 318, in order to pinch tissue, when the snare loop 318 engages the tissue. In this case, the pinching mechanism may include pinching structures 334 having pairs of pincer elements or hooks positioned over different portions of the peripheral structure of the snare loop 318, to grab the tissue at different locations.

[0049] The pinching structure 334 is now explained in conjunction with a cross-section view of the snare loop 318 shown in FIG. 3F. As shown, the pinching structure may include a pair of pincer elements 334(a) and 334(b). An inner pincer element 334 (a) may be capable of rotating with respect to an outer pincer element 334 (b). Once the inner pincer element 334 (a) has rotated substantially, a portion of the underlying tissue is grabbed between the two pincer elements. In some cases, both the pincer elements 334 (a) and 334 (b) may also rotate toward each other, to quickly grab the tissue. It is contemplated that any number of pincer elements may be disposed on the snare loop 318.

[0050] To facilitate rotation of the inner pincer elements 334 (a) with respect to the outer pincer elements 334 (b), a suitable mechanism may be coupled to the pinching structure 334. In one embodiment, an electrical actuating mechanism may be disposed at the proximal portion of the elongate shaft 302, which may be coupled to each of the inner pincer elements 334 (a), to facilitate their rotation with respect to the outer pincer elements 334 (b). The outer pincer elements 334 (b) may be magnetized to create a magnetic field around the inner pincer elements 334 (a). The electrical actuating mechanism may pass an electric current through the inner pincer element 334 (a), and being placed in the magnetic field of the outer pincer element 334 (b), the inner pincer element 334 (a) may experience a torque, and rotate toward the outer pincer element 334 (b). Further, the pinching structure may also extend only partially across the length of the snare loop 318, in order to facilitate grabbing of the tissue at specific desired portions.

[0051] FIGS. 4A-4C illustrate views of a medical device 400 for resecting tissue, in accordance with another embodiment of the present disclosure.

[0052] FIG. 4A shows a perspective view of the medical device 400. An elongate shaft 402 incorporates an actuation member 406 extending outwards distally, from the shaft 402. In a manner similar to the one or more previous embodiments of the disclosure, multiple snare wires may extend outwards from the snare loop. The snare wires cooperate and join to form a snare loop 418 that may engage an underlying tissue, to resect tissue. In the illustrated embodiment, multiple spaced apart ring shaped elements 422 may be positioned around, and secured to different portions of the snare loop 418. The ring elements 422 may function as traction rings, and can be configured to increase traction during engagement of the snare loop 418 with the underlying tissue, in order to reduce slippage of the snare loop 418 over the tissue. In order to secure the ring elements 422 to different portions of the snare loop 418, multiple grooves or indentations may be provided on the snare loop 418 at those portions. Appropriate ways to attach and fixedly secure the ring elements 422 to the loop 418 include press-fitting, swaging, snap-fitting, etc. Further, though shown as extending across the entire length of the snare loop 418, the ring elements 422 may also be positioned to extend only partially around the snare loop, in order to enhance frictional engagement only at specific intended portions of the underlying tissue.

[0053] FIG. 4B shows a cross-sectional view of an exemplary ring element 422 that may be secured over the snare loop 418 shown in FIG. 4A. Though shown as being of a C-shaped structure, the ring element 422 may also have a different cross-section. The opening 422 (a) within the ring element 422 may facilitate securing the ring element 422 to the snare loop 418. Specifically, through the opening 422 (a), the ring element may be press-fitted, snapped on to, or crimped to the snare loop 418. Further, each ring element 422 may have a rough irregular outer surface, for example, a knurl, to enhance frictional engagement (i.e., to increase traction) of the snare loop to the tissue.

[0054] FIG. 4C is a partial perspective view showing the ring elements 422 configured to engage the snare loop 418. As mentioned earlier, the snare loop 418 may have multiple grooves or indentations provided over its peripheral surface, to facilitate attachment of the ring elements 422 to the snare loop. As shown, each ring element 422 may have a partially cylindrical cross-section at its front portion, to substantially surround the snare loop at a specific location. Further, the backwards cross-sectional structure of each ring element 422 may be tapered, and of a decreasing nature. This may facilitate easy retraction of the snare loop into the actuation member 406, without any obstruction being experienced due to the ring elements 422.

[0055] FIG. 5 shows a medical device 500 for resecting tissue from a target site, where an auxiliary loop 522 may be provided at a distal tip of a larger snare loop 518. Similar to the embodiments described earlier, the larger loop 518 may be formed by snare wires 510 extending outward from an actuation member contained within an elongate shaft 502. The auxiliary loop 522 may engage a relatively smaller portion of an underlying tissue, to pinch and resect that portion. For example, as the auxiliary loop 522 is drawn closed, it may provide more traction or friction to the larger snare loop 518, enabling it to ensnare a larger portion of the tissue. Further, the provision of an auxiliary loop at a distal portion, or, any other peripheral portion of a larger snare loop, though explained in context of the current embodiment, may also be incorporated in any of the previously described embodiments. An additional actuation mechanism may be provided to actuate the auxiliary loop 522 independently. Further, in certain embodiments, both the larger loop 518 and the auxiliary loop 522 may be actuated through a common actuation mechanism.

[0056] In all the non-limiting embodiments described herein, materials used to manufacture the actuation member, the elongate shaft, the snare wires, and other components that may interact with portions of the human body, may include a rigid and/or a flexible material either in combination or alone. Additionally, exemplary materials may include metals, polymers, alloys, composite, or the like, either in combination or alone. In some embodiments, the material employed may include a self-expandable material such as a shape memory material, Nitinol, for example. Other suitable material may also be contemplated without departing from the scope and spirit of the disclosure.

[0057] Embodiments of the present disclosure may be applicable to any medical or non-medical procedure. In addition, certain aspects of the aforementioned embodiments may be selectively used in collaboration, or removed, during practice, without departing from the scope of the disclosure.

[0058] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.