WO2008044615A1

WO2008044615A1 - Endoscopic snare

Info

Publication number: WO2008044615A1
Application number: PCT/JP2007/069522
Authority: WO
Inventors: Atsunori Kozuki; Hiroshi Horikawa
Original assignee: Johnson & Johnson Kabushiki Kaisha
Priority date: 2006-10-02
Filing date: 2007-09-28
Publication date: 2008-04-17
Also published as: JP2010505450A

Abstract

[Problem] To provide an endoscopic snare in which even if a snare loop is repeatedly projected out of and drawn into a sheath, the snare loop can be held in an ideally curved loop configuration to permit efficient capturing polyps of various shapes. [Means for Solving the Problem] In an endoscopic snare in which a snare wire 2 slidably received in a flexible sheath 1 is projected out of the distal end of the sheath 1 to form a snare loop 2a for tightly binding and cauterizing a polyp in a body cavity, the snare loop 2a has formed therein at predetermined positions inward protrusions 2b engageable with the distal end portion of the sheath when the snare wire 2 is retracted into the sheath and the engagement of the inward protrusions 2b with the distal end portion of the sheath 1 enables the snare loop 2a to form an ideally curved loop configuration for tightly binding and cauterizing the polyp.

Description

DESCRIPTION

ENDOSCOPIC SNARE TECHNICAL FIELD [0001]

The present invention relates to an endoscopic snare that has a snare loop for tightly binding and cauterizing a polyp in a body cavity. BACKGROUND ART [0002] In general, an endoscopic snare is provided with a flexible sheath for insertion into a body cavity and a snare wire slidably received in the sheath, and the endoscopic snare is configured such that the snare wire is projected out of the tip or distal end of the sheath to form a snare loop for tightly binding and cauterizing a polyp in a body cavity. [0003]

In such endoscopic snares there are used various loop configurations devised to ensure tight binding of polyps of different sizes; the loop configurations can be roughly divided into elliptic and polygonal configurations in a horizontal plane, and in either case the loop length projecting out of the distal end of the sheath is greater than the loop breadth. [0004]

With the loop configuration of the type that the snare loop projecting out of the distal end of the sheath is longer than the loop breadth, however, the snare loop lacks resiliency high enough to capture polyps. As a solution to this problem, there is already known a polygonal snare loop configuration in a horizontal plane which has a plurality of outwardly convexities formed by first to third loop segments extending outwardly from the distal end portion of the snare loop and fourth loop segments contiguous to the third segments but extending therefrom in a direction in which to reduce the breadth of the loop, the second loop segments being the shortest and the fourth segments being the longest. This configuration enables the snare loop to expand even when the length of the loop projecting out of the sheath is short (see, for example, patent document 1). [0005] [Patent document] Pat. Kokai Publication No. 2001-292960 ([0027],

Fig. 1)

DISCLOSRE OF THE INVENTION [Problem to be Solved by the Invention] [0006] It is stated in patent document 1 that the above-described configuration of the endoscopic snare provides an expanse of the snare loop wide enough to tightly bind a small polyp as well even when the loop length extending from the distal end of the sheath is short, but an increase in the length of the snare loop extending out of the distal end of the sheath still causes a decrease in the loop breadth, making it difficult to capture polyps. [0007]

To avoid this, in a conventional endoscopic snare, the snare wire may also be preformed such that the snare loop extending out from the distal end of the sheath is generally circular in its entirety. With the snare loop of such a circular configuration, however, since retracting the snare loop into the sheath will cause an overload on the snare wire in a direction in which to reduce the loop diameter at the tip end portion of the sheath, repeated cycles of projecting the snare wire out of and retracting it into the sheath will permanently deform the snare wire into an elliptic configuration in a horizontal plane in which the loop length projecting out of the distal end of the sheath is greater than the loop breadth, making it impossible to provide ideally curved circular loop configurations that permit efficient capturing polyps of various shapes. [0008] The present invention is intended to solve such problems as mentioned above, and has for its object to provide an endoscopic snare that repeated cycles of projecting the snare loop out of and retracting it into the sheath will not hinder the action of holding the snare loop kept in ideally curved circular configurations that allow efficient capturing polyps of various shapes. [Means for Solving the Problem] [0009]

In the endoscopic snare according to the present invention in which a snare wire slidably received in a flexible sheath is projected out of the distal end thereof to form a snare loop for tightly binding and cauterizing a polyp in a body cavity, the snare loop has at predetermined positions opposed inward protrusions by which the snare loop is guided into and held in a high-profile operative state wherein a plurality of predetermined loop configurations is provided for tightly binding polyps of different shapes. [Effect of the Invention] [0010]

According to the present invention, at the time of retracting the snare wire inserted into the sheath and projected out of the distal end of the sheath to form the snare loop, the inward protrusions formed in the snare loop at predetermined positions permit reduction of the loop diameter while keeping the plurality of loop configurations in the snare loop. Further, at the time of pushing out the snare wire the inward protrusions allow elastic expansion of the loop in its breadthwise direction while keeping the plurality of loop configurations in the snare loop. Accordingly, repeated cycles of pushing the snare loop out of and retracting it into the sheath will not incur permanent deformation of the snare loop in the direction in which to decrease the loop breadth; hence, the present invention produces the effect of efficiently capturing polyps of various shapes by the snare loop. [Best Mode for Carrying out the Invention] [0011] Embodiment 1 Fig. l(A) is a perspective view of an endoscopic snare according to Embodiment 1 of the present invention, with the snare loop retracted in the sheath. Fig. 1(B) is a perspective view of the Fig. 1(A) embodiment, with the snare loop pushed out of the sheath. Fig. 2 is an enlarged sectional view of Fig. 1(B). Fig. 3 is an enlarged sectional view of the part A in Fig. 2, showing the principal part of a snare wire manipulating system. Fig. 4 is an enlarged sectional view of the part B in Fig. 2. Fig. 5 is a perspective view showing an outward appearance of an operating slider of the snare wire manipulating system. Fig. 6 is an enlarged perspective view of the snare wire manipulating system in Fig. 1(B). Fig. 7 is a perspective view of the snare wire manipulating system of Fig. 6, viewed from a different angle. Fig. 8 is a sectional view showing the snare loop in relation to the sheath. [0012]

The endoscopic snare of Fig. 1 is provided with: a hollow, tubular flexible sheath 1 that is inserted into a body cavity; and a snare wire 2 received in the sheath 1 in a manner to be slidable in its axial direction. The snare wire 2 is formed from a material that can be held in a predetermined configuration, preferably, formed of a difficult-to-deform, superelastic member (a superelastic wire rod) that forms a snare loop 2a for tightly binding and cauterizing a polyp in a body cavity. [0013]

A description will be given first of the configuration of the snare loop 2a that is the central technical idea of the present invention.

The inventors of this application have made approaches to an ideal snare loop configuration for efficiently capturing polyps of different shapes, and after their studies on various aspects of the ratio between the length of the loop projecting out from the distal end of the sheath and the loop breadth, they have found that a substantially circular loop configuration is preferred which contains a plurality of ideally curved loop configurations that permits tight binding of polyps of different shapes and sizes. As long as it has such a substantially circular configuration, the snare loop produces novel and satisfactory effects, but it is the most desirable, in particular, that the substantially circular loop configuration has approximately a 1-to-l ratio between the loop length from the distal end of the sheath and the loop breadth. Furthermore, the present invention realizes a distinctive technical idea for maintaining the most desirable snare configuration.

With reference to the drawings, the present invention will hereinbelow be described in detail. [0014] The snare loop 2a is formed along circular loci each extending rearwardly of an outwardly convex turned-back portion 2c at the distal end of the loop. And, opposed loop segments of the snare loop 2a in its breadthwise direction are bent inwardly at positions just midway between the distal end of the sheath 1 and the outwardly convex turned-back distal end portion of the snare loop 2a, forming inward protrusions 2b such as inwardly constricted portions as shown in Figs. 1, 2 and 9 (which are constricted portions, inwardly projected portions or the like in embodiments of Figs. 10 to

12).

When the snare loop 2a pushed out of the sheath 1 is in a high-profile operative or enlarged state wherein the snare loop is in its full-open position, the inward protrusions 2b are 1 mm or more inside tangential lines between outside vertexes of two circular arcs formed on both sides of each inward protrusion 2b, and the two segments of the snare wire 2 forming the inward protrusions 2b cross each other at an angle in the range of between 60 and 160 degrees.

With the inward protrusions 2b, the snare loop 2a maintains in its entirety a plurality of predetermined loop configurations for tightly binding polyps as depicted in Figs. 1, 2 and 9. That is, the inward protrusions 2b provide two ideally curved loop configurations that allow ease in tightly binding polyps by the snare loop 2a. In Embodiment 1 shown in Figs. 1, 2 and 9, in particular, the inward protrusions 2b provide approximately a 1-to-l ratio between the loop length from the distal end of the sheath 1 and the loop breadth; namely, by the inward protrusions 2b, the snare loop is guided to and held in a substantially gourd-shaped configuration containing two or more contiguous substantially circular portions. [0015]

As the snare wire 2 is drawn into the sheath 1, the size of the loop decreases, bringing the inward protrusions 2b into engagement with the distal end portion Ia of the sheath 1. The snare wire 2 whose inward protrusions 2b engage the distal end portion Ib of the sheath 1 may be formed not only by a stainless steel stranded wire but also of a superelastic material such as NlTINOL.

Even with the stainless steel stranded wire, it is possible to hold one ideal circular configuration and to obtain predetermined effects, but in the case of using the superelastic material, especially, its elastic force also contributes to the formation of one ideal circular configuration in the snare loop 2a. That is, as depicted in Figs. 1, 2 and 9, the loop diameter is reduced in the direction in which to provide approximately a 1-to-l ratio between the loop length from the distal end of the sheath 1 and the loop breadth, forming a reduced-diameter, low-profile loop configuration of an ideal circular curve for tightly binding polyps.

Moreover, when the snare loop 2a is pushed out of its retracted position in the sheath 1, the inward protrusions 2b impart to the snare loop 2a an elastic restoring force which acts in the direction toward the high-profile operative, full-open position of the loop where the loop length from the distal end of the sheath 1 and the loop breadth bear the afore-mentioned approximately 1-to-l ratio. This enables the snare loop 2a to maintain an increased-diameter, high-profile, ideally curved loop configuration capable of tightly binding polyps . [0016]

Next, a description will be given of a manipulating system for the snare wire 2. As shown in Figs. 1 and 2, the sheath 1 has its base end portion inserted and fixedly fitted in a sheath fixing tube or sleeve 3, which has in turn its base end portion fixedly fitted in an end of a manipulator body

4. The manipulator body 4 has cut therein axially a slider guide groove 5 on the other end opposite from the sleeve 3, and in the slider guide groove 5 there is slidably received an operating slider 6 having a high-frequency electrode 7. The operating slider 6 has the proximal end portion of the snare wire 2 fixedly secured thereto and slidably received in the sheath 1, and the snare wire 2 is connected to the high-frequency electrode 7. Accordingly, the snare wire 2 is pushed out from and drawn into the sheath 1 through to-and-fro sliding movements of the operating slider 6 along the guide groove

5. As depicted in Figs. 2 and 3, a protective pipe 8 for protecting the snare wire 2 is fixed to the operating slider 6 between it and the manipulator body 4.

[0017]

Turning next to Fig. 9, the operation of the manipulator will be described.

As the operating slider 6 is moved back in the direction indicated by the arrow when the snare loop 2a is in the full-open position as shown in Fig. 9(A), the snare loop 2a at the distal end of the snare wire 2 connected to the slider 6 is gradually drawn into the sheath 1, bringing the inward protrusions 2b of the snare loop 2a into engagement with the distal end portion Ia of the sheath 1. In this engagement state the snare loop 2a retains the reduced-diameter, low-profile loop configuration formed by an ideal circular curve (see Fig. 9(B)). Thus, it is possible to tightly bind a large polyp when the snare loop 2a is in the state of Fig. 9(A) and a small polyp when the snare loop 2a is in the state of Fig. 9(B). With the snare loop 2a configured to be deformable into a plurality of configurations (two in Embodiment 1) as described above, polyps of various sizes and shapes can be tightly bound with ease and with certainty. In the state in which the snare loop 2a is further retracted into the sheath 1 by further sliding back the operating slider 6, a high-frequency current is supplied to the snare loop 2a. By further backward sliding movement of the operating slider 6 in the direction indicated by the arrow, the snare loop 2a of the reduced-diameter loop configuration is further drawn in its entirety into the sheath 1, cutting the polyp (see Fig. 9(C)). By forward movement of the slider 6 in a direction opposite to that indicated by the arrow when the snare loop 2a is entirely retracted in the sheath 1 as depicted in Fig. 9(C)₅ the snare wire 2 and consequently the snare loop 2a is paid out of the distal end of the sheath 1 and into the low-profile operative state and then into the high-profile operative state as shown in Figs. 9(B) and 9(A), respectively. In the Fig. 9(A) high-profile operative state wherein the snare loop 2a is in full-open position, the snare loop 2a holds two ideally curved loop configurations. [0018]

As described above, according to Embodiment 1, since the inward protrusions 2b symmetrically disposed in the opposite wire segments in the breadthwise direction of the snare loop 2a extending from the distal end portion of the sheath 1, and since the snare wire 2 is formed of a difficult-to-deform, superelastic material, the snare loop 2a holds in its entirety two circular configurations each of which bears approximately a 1-to-l ratio between the loop length from the distal end of the sheath 1 and the loop breadth. [0019] Further, by retracting the snare loop 2a into the sheath 1, the inward protrusions 2b is brought into engagement with the distal end portion Ia of the sheath 1 to generate a force by which the snare loop 2a is guided to and held in the afore-mentioned low-profile operative state wherein the snare loop 2a retains one ideally curved circular configuration. In other words, the snare loop 2a can be pulled into the low-profile operative state while keeping the ideally curved circular configuration. In the case of pushing the snare loop 2a out of the sheath 1, the inward protrusions 2b enable the snare loop 2a to elastically expand in its breadthwise direction while maintaining ideally curved circular configuration(s). Accordingly, it is possible to prevent that repeated cycles of projecting the snare loop 2a out of and drawing it into the sheath 1 cause permanent deformation of the snare loop 2a in the direction in which to decrease the loop breadth —this ensures efficient capturing polyps of various shapes. [0020] Embodiment 2

Fig. 10 is a top plan view of a snare loop of an endoscopic snare according to Embodiment 2 of the present invention, showing the sheath in section.

In Embodiment 1 the inward protrusions 2b of the snare loop 2a are disposed just midway between the distal end of the sheath 1 and the distal end of the snare loop 2a extending therefrom, but in Embodiment 2 the inward protrusions 2b are provided in constricted or inwardly projecting form.

That is, the inward protrusions 2b are each formed symmetrically in the snare loop 2a at a position nearer to the proximal end of the loop 2a (the distal end of the sheath 1) than the inward protrusions 2b in Embodiment 1. The inward protrusions 2b are brought into engagement with the distal end portion Ia of the sheath 1 when the snare wire 2 is retracted thereinto. [0021]

According to Embodiment 2, the inward protrusions 2b are provided in constricted or inwardly projecting form, and their engagement with the distal end portion Ia of the sheath 1 enables the snare loop 2a to enter its reduced-diameter state wherein it holds an ideally curved configuration larger in diameter than in the case of Embodiment 1. [0022] Embodiment 3 Fig. 11 is a top plan view of a snare loop of an endoscopic snare according to Embodiment 3 of the present invention, showing the sheath in section.

In Embodiment 3, the inward protrusions 2b are formed in constricted or inwardly projecting form as in the case of Embodiment 2, and they are disposed at positions nearer to the distal end of the sheath 1 than in the case of Embodiment 2, and their engagement with the distal end portion Ia of the sheath 1 enables the snare loop 2a to form an ideally curved loop configuration larger in diameter than in the case of Embodiment 2. [0023]

Embodiment 4

Fig. 12 is a top plan view of a snare loop of an endoscopic snare according to Embodiment 4 of the present invention, showing the sheath in section. In Embodiments 1, 2 and 3 two inward protrusions 2b are formed in the snare loop 2a, but in Embodiment 4 four inward protrusions 2b are formed in the snare loop 2a. By step-by-step engagement of the two pairs of inward protrusions 2b with the distal end portion Ia of the sheath 1, the diameter of the snare loop 2a can be reduced on a stepwise basis to form an ideally curved loop configuration.

[Brief Description of the Drawings] [0024]

[Fig. 1] Fig. 1(A) is a perspective view of an endoscopic snare according to Embodiment 1 of the present invention, with the snare loop retracted in the sheath, and Fig. 1(B) is a perspective view of the Fig. l(A) embodiment, with the snare loop pushed out of the sheath. [Fig. 2] Enlarged sectional view of Fig. 1(B).

[Fig. 3] Enlarged sectional view of the part A in Fig. 2, showing the principal part of a snare wire manipulating system. [Fig. 4] Enlarged sectional view of the part B in Fig. 2. [Fig. 5] Perspective view showing an outward appearance of an operating slider of the snare wire manipulating system.

[Fig. 6] Enlarged perspective view of the snare wire manipulating system in Fig. 1(B). [Fig. 7] Perspective view of the snare wire manipulating system of Fig.

6, viewed from a different angle.

[Fig. 8] Sectional view showing the snare loop in relation to the sheath.

[Fig. 9] Diagram explanatory of the manipulation of the snare wire. [Fig. 10] Top plan view of a snare loop of an endoscopic snare according to Embodiment 2 of the present invention, showing the sheath in section.

[Fig. 11] Top plan view of a snare loop of an endoscopic snare according to Embodiment 3 of the present invention, showing the sheath in section.

[Fig. 12] Top plan view of a snare loop of an endoscopic snare according to Embodiment 4 of the present invention, showing the sheath in section.

[Explanation of Numerals] [0025] 1 : Sheath

Ia: Distal end of the sheath 2: Snare wire 2a: Snare loop 2b: Inward protrusions

2c: Turned-back distal end portion 3: Sleeve for fixing the sheath 4: manipulator body 5: Slider guide groove 6: Operating slider : High-frequency electrode: Protective pipe

Claims

1. An endoscopic snare in which a snare wire slidably received in a flexible sheath is projected out of the distal end of said sheath to form a snare loop for tightly binding and cauterizing a polyp in a body cavity, characterized in that the snare loop has at predetermined positions opposed inward protrusions that bring said snare loop into a state of forming a plurality of predetermined loop configurations for tightly binding polyps of different shapes.

2. The endoscopic snare of claim 1, characterized in that said plurality of loop configurations are each rendered by said inward protrusions into an ideally curved loop configuration.

3. The endoscopic snare of claim 1 or 2, characterized in that said ideally curved loop configurations are substantially circular.

4. The endoscopic snare of claim 2 or 3, characterized in that said ideally curved loop configurations have a gourd-like configuration containing at least two contiguous substantially circular portions.

5. The endoscopic snare of any one claims 2 to 4, characterized in that when said snare wire is retracted into said sheath, said inward protrusions engage the distal end portion of said sheath, thereby providing said each ideally curved loop configuration.

6. The endoscopic snare of any one of claims 1 to 5, characterized in that said inward protrusions impart to said snare loop a force by which said snare loop is bent in a direction in which to provide a 1-to-l ratio between the loop length and the loop breadth.

7. The endoscopic snare of any one of claims 1 to 6, wherein said snare wire is formed of a material which enables said snare loop to be held in a predetermined configuration.

8. The endoscopic snare of any one of claims 1 to 7, characterized in that said snare wire is formed of a diffϊcult-to-deform, superelastic material.