FIELD OF THE INVENTION

The present invention relates to a device and method for use in snare resection and/or cauterization operations inside body cavity like the colon. The device of the invention is built like standard cold or hot snare, with the addition of flexible polymeric sling attached to the snare distal loop.

BACKGROUND OF THE INVENTION

In a conventional snare operation, an endoscope is inserted into an internal cavity of a patient, e.g., into the colon, and is used to locate abnormal tissue growths such as polyps in the internal cavity. Upon locating a polyp or other tissue growth which is to be removed, a snare having main flexible metal shaft covered by a flexible polymer sheath, is extended through the working channel of the endoscope, and slides in the distal direction so that a metal cutting loop (cauterization loop in hot snaring) connected to the metal shaft is fully protruded from the distal end of the endoscope working channel. The loop and the endoscope are manipulated from outside of the patient to pass the loop over the polyp or tissue growth. The metal shaft is then withdrawn in the proximal direction, relative to the snare sheath, to tighten the loop around a base region or stalk of the polyp, against the snare sheath. Once the loop is in tight contact with the base region of the polyp, an electrical current is passed through the loop via the snare metal shaft, if hot resection is used. Generally, as the loop is closed about the base region of the polyp, electrical current is transmitted through the narrowed tissues to generate sufficient heat to cut and cauterize the polyp.

For cold snare technique, the metal loop wire, usually a thin wire, is further pulled against the snare polymeric sheath to cold cut the polyp.

After snare polypectomy there is a need to remove polyps for pathological analysis. However, it is frequently difficult to capture the polyp and retrieve it from the patient via the endoscope working channel. Sometimes the snare loop is used in an effort to ensnare the polyp. Other capture techniques involve the use of biopsy forceps, a dedicated basket, or the application of suction. In using biopsy forceps or other devices like baskets, the snare is removed from the working channel of the endoscope and replaced with the forceps / basket. When using suction, the snare is removed, and a vacuum is applied via a suction channel of the endoscope to suck the polyp out. No matter which specific technique is used, polyps are frequently lost inside the colon or escape from the capturing instrumentality and fall into the colon (or other cavity). Especially in cases where the polyp is small, the effort and time expended in retrieving the severed polyp may rival or even exceed the effort and time required to locate and cut the polyp. In extreme cases, the endoscope must be removed without the polyp and the patient given an enema in an attempt to flush out the polyp from the colon.

Furthermore, there are numerous cases where a severed polyp is never recovered. Sometimes, the polyp is cut again during the retrieval attempt. In all such cases, the pathologist is unable to determine whether the polyp contains carcinoma in situ (localized) or infiltrative carcinoma (spread). The patient must then undergo a colon resection, sometimes unnecessarily.

Currently there are few snares that combine polyp cautery and polyp capturing. Some snares have the snare loop positioned next to a net. The polyp should supposedly fall into the net for removal with the snare. There are separate handle sliders or knobs 1) to open and close the snare, and 2) to use/close the net to catch a polyp. One problem using such hot (RF cautery) snares is that the net may interfere with the metal loop RF cautery of the polyp.

Another problem using a net is that the endoscope camera image is not aligned with the direction of gravity and can be rotated at any angle without any such indication to the user. Often the polyp, instead of being seen falling down after cutting or cautery with the loop, is seen moving sideways or upwards! Since there is no advanced knowledge of the direction of gravity related to the camera and camera image (the long endoscope is constantly rotated to move in and out inside the colon), the net can catch polyps only in a small percentage of the cases, and therefore is not used very often.

SUMMARY OF THE INVENTION

The present invention is directed to a device and method for snare resection technique wherein both the capture and retrieval of polyps is facilitated.

One embodiment employs a single-handle (slider) axial movement, which activates both the snare loop closing and polyp cutting mechanism, and the polyp capturing mechanism. One advantage is the single slider movement is very easy and intuitive for the user, as the polyp capturing is done with the same movement of the snare loop closing. Another advantage is the device does not depend on the gravity direction alignment of the endoscope camera image.

In one embodiment, a snare may have a metal loop, with the addition of a novel flexible sling attached to the snare distal section or to the snare distal metal loop.

The snare instrument may include an elongate flexible tubular sheath, e.g., made from PTFE or HDPE tube, having proximal and distal ends, a flexible main metal wire or shaft, e.g., made from braided stainless steel wire or monofilament nitinol wire, having proximal and distal ends extending through and axially movable relative to the sheath, a metal snare loop, e.g., made from braided stainless steel wire or monofilament nitinol wire, at the distal end of the metal shaft, and a handle body coupled to the proximal ends of the sheath and the handle slider connected to the metal shaft for moving the metal shaft axially relative to the sheath.

The snare metal loop has a proximal portion which extends and opens along an angle or curve relative to the shaft when pushed out distally from the sheath. As such, when the snare loop is axially moved beyond the distal end of the sheath, the distal portion of the snare loop (the portion adapted to engage a polyp) is opened and oriented substantially parallel to the snare sheath.

In hot snare, an electrical supply (e.g., monopolar RF) is operatively connected to the snare metal shaft for passing an electrical current to the metal loop via the metal shaft , while a manually activated handle slider is operatively connected to the metal shaft for longitudinally sliding the metal shaft along the polymeric sheath in alternately opposite directions, to close (or open) the loop.

The flexible sling of the invention is used to capture and retrieve the polyp. The sling includes a sling base that may lean on the metal loop distal tip, and two long and thin flexible members. The two long members, e.g., two cords, may be elastic members that are attached in their proximal ends to the snare loop, far enough from the distal loop section that is actually used to cut (cold or hot) a polyp. Alternatively, the two members may only be flexible but not elastic, and are attached to a small elastic spring, and the spring is attached to the metal loop proximal side or to the metal shaft distal end.

When cutting a polyp, the sling base is in direct contact with the polyp and may move distally while the two flexible members stretch or move backwards (proximally) while stretching (or compressing) the spring, according to the polyp size. After the polyp is cut, it is trapped/locked between the sling base and the shaft distal end.

If the polyp size is small enough, the snare is pulled out from the endoscope working channel, together with the polyp. If the polyp is much larger than the endoscope working channel, then the sling-snare with the polyp and the endoscope, are pulled back together from the patient colon.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a simplified illustration of a snare with a loop in a fully open position.

Fig. 2 is a simplified illustration of the snare with the loop in a closed position.

Fig. 3 is a simplified illustration of the sling of the invention including a base and two thin elastic members (e.g., cords).

Fig. 4 A is a simplified illustration of the sling of the invention including a thick disc base and two thin elastic members (e.g., cords).

Fig. 5 is a simplified illustration of the sling of the invention including a short elastic tube base and two thin elastic members (e.g., cords).

Fig. 6 A is a simplified illustration of the sling of the invention including a short tube base with a slit shaped lumen, and two thin elastic members (e.g., cords).

Figs. 6B and 6C are simplified illustrations of the sling of the invention including an elastic thin metal ring surrounding a thin elastic polymer disc with a slit, and two thin elastic members (Fig. 6B shows the metal ring in a fully open position, and Fig. 6C shows the metal ring partially inside the sheath).

Fig. 7 is a simplified illustration of the sling having a base and two flexible elastic members assembled on the snare loop in an open loop position.

Fig. 8 is a simplified illustration of the sling Fig. 7 with teeth profile at the sheath distal end.

Fig. 9 is a simplified illustration of polyp inside the partially open loop of the sling.

Fig 10 is a simplified sectional illustration of the polyp inside the almost fully closed metal loop, just before polyp resection.

Fig 11 is a simplified sectional illustration of the polyp locked between the sling base and distal sheath end after polyp resection.

Fig. 12 is a simplified illustration of the sling including a base connected to two thin flexible, but not elastic members at their distal end, wherein the two thin members are connected to a metal spring at their proximal side, and wherein the spring stretching allows the sling base and the two members to move backwards relative to the metal loop to lock or catch a polyp.

Fig. 13 is a simplified illustration of the sling including a sling base connected to two thin flexible non-stretchable members at their distal end, and the two thin members are connected to a spring or small disc proximal to the spring, wherein the spring compression allows the sling base and two members to move backwards relative to the metal loop to lock or catch a polyp.

Fig 14 is a simplified sectional illustration of the polyp locked between the sling base of the sling with spring and distal sheath end after polyp resection.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to Figs. 1-2 and 7. The device 1, in accordance with a non-limiting embodiment of the present invention, includes a snare loop 10, which may be made of metal or other suitable material. As will be described below, the device 1 also includes a flexible sling assembled over and attached to the snare loop 10.

The snare device 1 may include, without limitation, an elongate tubular sheath 11, e.g., made from a low friction polymeric material such as PTFE (polytetrafluoroethylene) or HDPE (high density polyethylene), having proximal and distal ends, a flexible (or non-flexible) shaft 12, e.g., made from braided stainless steel wire or single flexible nitinol wire, having proximal and distal ends extending through and axially movable relative to the sheath 11. Flexible shaft 12 may be coupled to snare loop 10, such as by a small metal crimped tube 23.

A handle or handle assembly 14 may be coupled to the proximal end of the sheath 11. A slider 13 is arranged to move axially over handle 14. The slider 13 is coupled with the proximal end of flexible shaft 12. Axial movement of slider 13 causes axial movement of flexible shaft 12 relative to the sheath 11, and depending on the direction of the axial movement, either deploys loop 10 out of sheath 11 (Fig. 1) or draws loop 10 into sheath 11 through the distal end 30 of sheath 11 (Fig. 2). (Other movements than axial may also be used.)

The snare loop 10 may have a normally open pre-shaped position, e.g., an oval or ovate shape, having a proximal portion which extends along an angle or curve relative to the shaft 12 when loop 10 is pushed out distally from the sheath 11. As such, when the snare loop 10 is axially moved beyond the distal end of the sheath 11, a distal portion 19 of the snare loop 10 is adapted to engage a polyp, and is oriented substantially parallel to the snare sheath 11. Other shapes of such an open loop 10 are also contemplated, such as circular, elliptical, polygonal, irregular, etc..

If desired to make the sling-snare of the invention a hot snare, an electrical supply (e.g., monopolar RF) is operatively connectable through a probe 22 on slider 13 to the snare shaft 12 for passing an electrical current to the snare loop 10 via the metal shaft 12. Once loop 10 is in contact with the base region of a polyp, an electrical current is conducted through loop 10 via the (metal wire) shaft 12 to generate sufficient heat to cut and cauterize the polyp.

If the snare sling of the invention is used as a cold snare, no electrical energy is used, and the polyp is cut by the loop 10 movement into sheath 11.

Reference is now made to Figs. 3-6, which illustrate the elastomeric sling 15 assembled over and attached to the snare loop 10.

The elastic sling 15 may include a main base or disc 16 and at least two long and thin elastic members 17, 18.

Sling 15 may be made from one piece of an elastomeric material, such as but not limited to, rubber, latex, neoprene, or silicone rubber, for full elasticity of the sling and also for ease of manufacturing. However, alternatively, base 16 of sling 15 can be made of stiff er non-metallic and isolating materials, such as nylon or stiff silicone rubber, and the two elastic and non-conductive members 17,18 may be bonded or mechanically attached to disc 16.

Alternatively, as seen in Fig. 4, a sling 25 may be similar to sling 15, but instead of flat disc 16, the sling base is shaped like a thick disc or cylinder 26 which is more robust, and two thin elastic members 27,28 protrude therefrom.

Alternatively, as seen in Fig. 5, a sling 35 may be similar sling 25, with two thin elastic members 37 & 38 protruding from a tube 36 with a circular opening. This enables the sling to be assembled over the distal end 19 of loop 10, and improves attachment to polyps after their resection.

Alternatively, as seen in Fig. 6A, a sling 45 may be similar to sling 35, with two thin elastic members 47,48 protruding from a tube 46 having a slit shaped lumen 49, Slit 49 may be used to radially fix tube 46 over the distal tip 19 of loop 10. This allows pre-rotation of the sling before assembly over the loop distal tip 19, for better polyp attachment to sheath 11 after polyp resection, wherein the elastic members 47,48 overlap or envelop the polyp. Alternatively, as seen in Fig. 6B, a sling 55 may be similar to sling 15, but the sling base is made from a thin elastic ring 56, e.g., nitinol ring, covered by a very thin elastomeric layer 57, having a significantly larger diameter than sheath 11 to have better grip of the polyp. Two flexible elastic members 58 & 59 are coupled to ring 56. When pulling the sling 55 into sheath 11, the thin ring 56 with its elastomer cover 57 folds inside the sheath 11, as seen in Fig. 6C.

Reference is now made to Fig. 7, which illustrates elastic sling 35 with tube 36 assembled on distal tip 19 of snare loop 10. The two long thin elastic members 37, 38 are attached on opposing sides of the snare loop 10, for example, using adhesive, or crimpers tubes 20,21, or any other attachment methods known in the art, and are attached to attachment points on loop 10 far from the distal tip 19 which is actually used to cut the polyp. The sling flexible members 37, 38 can alternatively be attached directly to the shaft 12 instead of loop 10

When cutting polyp 2, the sling 35 with tube 36 is moving distally relative to distal tip 19 of loop 10, while the two elastic members 37,38 are stretched according to the polyp size. After the polyp is cut, it is locked between the sling tube, or disc if sling 15 or 25 is used, and the distal end 30 of shaft 11, as seen in Fig. 11.

As seen in Fig. 8, a distal end 31 of shaft 11 can be made with an edge having high friction or formed with multiple small teeth or other similar shapes or roughness, to increase friction with the polyp, thereby improving the capturing mechanism between the sling and the sheath.

Figs. 9, 10, and 11 illustrate steps of using the sling snare of the invention to resect a polyp. Fig. 9 illustrates the first step in which the user positions the snare loop 10 over a polyp 2. Fig. 10 illustrates the next step, in which loop 10 is pulled proximally by using the slider 13 (not shown in Fig. 10), until the polyp 2 touches the distal end 30 of sheath 11. Fig. 11 illustrates the final step. After the polyp 2 is resected by loop 10, it is held between the sling 35 with the elastic members stretched, and the sheath distal end 30.

Reference is now made to Figs. 12-14, which illustrate another embodiment with flexible members coupled to a biasing device, such as a coil spring.

In Fig. 12, a sling 60 may have two or more flexible but not elastic members, 61 & 62, e.g., made from PTFE cord or other non-conductive cords that withstand high temperature associated with polyp electric cautery, if the snare is a hot snare. For a cold snare, other cord materials like nylon or silk can be used. For example, the two flexible members 61 & 62 each pass through small metal rings or eyelets 63 that are welded to the inner side of loop 10, and are connected to a sling distal base 64 that can have a disc shape, tube shape and other structures described previously.

A barb 69 can be added to base 64, for better polyp attachment to the sling base, after polyp resection, which is true for all embodiments.

The proximal sides of the flexible members 61 & 62 may be connected to a biasing device, such as a small spring 65, e.g., stainless- steel spring, located over the proximal portion of snare loop 10 or distal portion of shaft 12. Members 61 and 62 may be tied to a small disc 66, formed with holes to tie the two flexible members, and which is welded to the distal end of spring 65, instead of being tied directly to the distal end of spring 65. Spring 65 may be welded or crimped using a crimping tube 67 to the snare shaft 12 at its proximal end.

The distal elongation of spring 65 allows base 64 of sling 60 and members 61 & 62 to axially move against the loop distal section 19, so as to lock polyp 2 after being resected by loop 10.

When cutting polyp 2, loop 10 is pulled proximally using handle slider 13 (not shown here), thereby cutting the polyp and then entering sheath 11. The sling base 64 is able to move distally relative to distal tip 19, thereby creating a gap between loop 10 and sling base 64, while at the same time, the elastic members 61,62 move to stretch spring 65 according to the polyp 2 size. After the polyp is cut, it is locked between the sling base 64 and distal end 30 of shaft 11.

Fig. 13 illustrates an alternative spring design, in which a spring 68 is a compressible spring, and members 61 & 62 are tied to the spring proximal side or to small disc 66 located at the spring proximal end, causing the spring to compress against crimped tube 23, thereby creating a gap between the distal end 19 of the loop 10 and the sling base 64, when locking a polyp between the sling base and the sheath.

Fig. 14 illustrates the sling with the compression spring at the final resection step, when the polyp 2 is resected. The polyp 2 is now held between the sling and distal end 30 by means of the flexible members 60 & 61, and spring 68 is significantly compressed.

After the completion of the polyp resection, the snare may be withdrawn from the endoscope working channel, together with the polyp. If it is hard to withdraw the polyp through the scope working channel biopsy-port valve, the biopsy-port may be temporarily removed. Alternatively a small stiff expansion tube having a diameter similar to the working channel diameter can be pre-inserted through the valve to allow easy polyp removal.

If the polyp is too large to pass through the scope working channel, the polyp and snare can be both withdrawn from the colon or other body lumen together with the scope.