Patent Publication Number: US-2021186559-A1

Title: Dilator

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of International Application No. PCT/JP2018/035091, filed Sep. 21, 2018. The content of the application is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a dilator. 
     BACKGROUND 
     Dilators are known for expanding a hole formed on the wall of a patient&#39;s digestive tract and the like for the purpose of treatment. The distal end of the dilator is inserted into the hole formed on the wall, and the hole is expanded by pushing a tapered portion into the hole. Such a dilator is, for example, disclosed in Japanese Unexamined Patent Application Publication No. 2008-11867. 
     SUMMARY 
     In such dilators, a sufficient propulsive force cannot be achieved at the tapered portion where the pushing resistance with respect to a hole or a constricted part increases, and the dilator cannot sufficiently expand the hole in some cases. Therefore, a configuration can be considered where a spirally-arranged protruding portion is formed by winding a coil around the outer periphery of the dilator, and the dilator is advanced due to a screw effect caused by rotation in order to ensure that an adequate propulsive force is obtained. 
     However, when a coil is wound only around the outer periphery of the dilator, the protruding portion that extends in a spiral may become displaced in a lengthwise axis direction. 
     The present disclosure has an object of providing a dilator that can suppress displacement, in a lengthwise axis direction, of a protruding portion that extends in a spiral. 
     In order to achieve the object, a dilator according to an embodiment of the present disclosure comprises: a hollow shaft having an outer diameter that increases from a distal end toward a proximal end; and a protruding portion that is provided on an outer periphery of the hollow shaft, and extends along the outer periphery of the hollow shaft in a spiral along a lengthwise axis direction of the hollow shaft; wherein the protruding portion has gaps between adjacent parts of the protruding portions along the lengthwise axis direction, a covering layer is provided that covers at least an outer peripheral surface of the hollow shaft, the outer peripheral surface being located in the gaps, and a top portion of the protruding portion is exposed. 
     Furthermore, the protruding portion may be provided so as to make contact with the outer peripheral surface of the hollow shaft, and the covering layer may be located between adjacent parts of the protruding portion, and make contact with an outer peripheral surface of the protruding portion. 
     Moreover, the covering layer may cover the outer peripheral surface of the hollow shaft, and the protruding portion may be provided on the covering layer. 
     Furthermore, the hollow shaft may comprise a first coil, in which one or more wires are wound into a hollow shape, and the protruding portion may comprise a second coil, in which one or more wires are wound around the outer peripheral surface of the hollow shaft. 
     According to the present disclosure, a dilator can be provided that can suppress displacement, in a lengthwise axis direction, of a protruding portion that extends in a spiral. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall view of a dilator according to an embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view of the vicinity of a boundary between a tapered portion and a proximal end portion of the dilator. 
         FIG. 3  is a cross-sectional view of the vicinity of a boundary between a tapered portion and a proximal end portion of a dilator according to a modification. 
         FIG. 4  is an overall view of a dilator according to a modification. 
         FIG. 5  is a diagram of a distal end portion of a dilator according to a modification. 
         FIG. 6  is a diagram of a distal end portion of a dilator according to a modification. 
         FIG. 7  is a diagram of a distal end portion of a dilator according to a modification. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensions of the dilator shown in the drawings are dimensions shown for the purpose of facilitating an understanding of the implementation details, and do not correspond to the actual dimensions. 
       FIG. 1  is an overall view of a dilator  1  according to an embodiment of the present disclosure.  FIG. 2  is a cross-sectional view of the vicinity of a boundary between a tapered portion  2 D and a proximal end portion  2 C of the dilator  1  according to the present embodiment. 
     Furthermore, in  FIG. 1  and  FIG. 2 , the left side of the drawing is the distal end side (distal side) inserted into the body, and the right side is the proximal end side (hand side, proximal side) operated by an operator such as a physician. 
     In  FIG. 1 , the dilator  1  comprises: a multilayered body  4  configured by a first coil  2  formed by winding one or more metal wires into a hollow shape, and a second coil  3  formed by winding a single metal wire around an outer peripheral surface  2 A of the first coil  2  in the opposite direction (Z-twisted) to the first coil  2  (S-twisted); a covering layer  5  that covers the outer peripheral surface  2 A of the first coil  2 ; and a hollow connector  6  connected to the proximal end of the multilayered body  4 . Note that the second coil  3  may be configured by a plurality of metal wires. 
     The wires constituting the first coil  2  and the second coil  3  are, for example, metal wires made of stainless steel or a superelastic alloy such as nickel-titanium, or are resin wires. 
     The first coil  2  is formed, for example, by winding ten metal wires made of stainless steel. The first coil  2  has a hollow shape, and is formed having a lumen  2 B that passes through from the proximal end to the distal end. The first coil  2  includes a proximal end portion  2 C, a tapered portion  2 D, and a distal end portion  2 E. The first coil  2  corresponds to a hollow shaft. 
     The proximal end portion  2 C is located on the proximal end side of the dilator  1 , and a connector  6  is connected to the proximal end thereof. Furthermore, the proximal end portion  2 C has a substantially constant outer diameter from the proximal end to the distal end. 
     The tapered portion  2 D is located on the distal end side of the proximal end portion  2 C, extends from the distal end of the proximal end portion  2 C toward the distal end side, and has an outer diameter that decreases toward the distal end side. 
     The distal end portion  2 E is located on the distal end side of the tapered portion  2 D, and extends from the distal end of the tapered portion  2 D toward the distal end side. The distal end portion  2 E has a substantially constant outer diameter from the proximal end to the distal end thereof. In this way, the outer diameter of the first coil  2 , which is a hollow shaft, increases from the distal end toward the proximal end. 
     The second coil  3  is, for example, a single metal wire which is wound around the outer peripheral surface  2 A of the first coil  2  in the opposite direction (Z-twisted) to the first coil  2  (S-twisted). Here, although the pitch of the metal wire is not particularly limited, the proximal end side represents a section having close winding in which adjacent parts (windings) of the metal wire are in contact with each other. The distal end side of the proximal end portion  2 C, the tapered portion  2 D, and the distal end portion  2 E represent a section having sparse winding in which adjacent parts (windings) of the metal wire are separated from each other. As a result of the part of the second coil  3  that is wound with a gap between windings (a sparsely wound part), a protruding portion  3 A is formed that makes direct contact with the outer peripheral surface  2 A of the first coil  2 , and which extends in a spiral on the outer periphery of the first coil  2  along a lengthwise axis direction (longitudinal direction) of the first coil  2 . The protruding portion  3 A has gaps  3 B between adjacent parts of the protruding portion  3 A (between adjacent parts of the metal wire) along the lengthwise axis direction of the first coil  2 . The dilator  1  can also be advanced by a rotation operation the dilator  1  as a result of a screw action of the protruding portion  3 A. 
       FIG. 2  is a cross-sectional view of the vicinity of a boundary between the tapered portion  2 D and the proximal end portion  2 C of the dilator  1 . 
     The covering layer  5  is made of resin, and as shown in  FIG. 2 , covers the outer peripheral surface  2 A of the first coil  2 , which is located in the gaps  3 B. That is to say, the covering layer  5  is located between adjacent parts of the protruding portion  3 A, makes contact with an outer peripheral surface  3 C of the protruding portion  3 A, and covers part of the outer peripheral surface  3 C of the protruding portion  3 A. A top portion  3 D (an outermost portion in a radial direction of the dilator) of the protruding portion  3 A is exposed to the outside from the covering layer  5 . The top portion  3 D is exposed to the outside from the covering layer  5 , for example, by covering the entire periphery of the protruding portion  3 A, including the top portion  3 D, with resin, and then peeling off the resin near the top portion  3 D. Examples of the resin constituting the covering layer  5  include biocompatible resin materials such as polyamide resins and fluororesins, and hydrophilic coating materials, and the thickness is, for example, 0.1 to 300 μm. 
     The length of the dilator in the present embodiment and the other embodiments described below is, for example, 2,000 mm, and preferably 1,600 mm to 2,500 mm; the length of the distal end portion  2 E is, for example, 10 mm, and preferably 0 mm (not present) to 100 mm; and further, the length of the tapered portion  2 D is, for example, 30 mm, and preferably 5 to 100 mm. The inner diameter at the distal end of the first coil  2  is, for example, 0.7 mm, and preferably 0.4 to 1.0 mm; and the inner diameter at the proximal end of the first coil  2  is, for example, 1.5 mm, and preferably 1.0 to 3.0 mm. The outer diameter at the distal end of the second coil  3  is, for example, 1.84 mm, and preferably 0.8 to 3.0 mm; and the outer diameter at the proximal end of the second coil  3  is, for example, 2.64 mm, and preferably 1.4 to 5.0 mm. Furthermore, the diameter of the metal wires of the first coil  2  is, for example, 0.21 mm, and preferably 0.1 to 0.5 mm; and the diameter of the metal wire of the second coil  3  is, for example, 0.36 mm, and preferably 0.1 to 0.5 mm. 
     The connector  6 , which is a grip portion, is a portion that an operator uses to push the dilator into the body, or to perform a rotation operation. The distal end of the connector  6  is connected to the proximal end of the first coil  2  and the proximal end of the second coil  3 . The connector  6  is made of resin, and has a hollow shape having a lumen which communicates with the lumen  2 B of the first coil  2 . 
     The dilator  1  of the present embodiment is provided with the covering layer  5 , which covers the outer peripheral surface  2 A of the first coil  2  located in the gaps  3 B; therefore, it is possible to suppress displacement, in the lengthwise axis direction, of the protruding portion  3 A that extends in a spiral. Furthermore, because the covering layer  5  is located between adjacent parts of the protruding portion  3 A, and makes contact with the outer peripheral surface  3 C of the protruding portion  3 A, it is possible to suppress displacement of the protruding portion  3 A in the lengthwise axis direction even further. The covering layer  5  enables the sliding properties of the dilator  1  to be improved, and the first coil  2  is capable of preventing pinching of the living tissue. Because the top portion  3 D of the protruding portion  3 A is exposed, compared to a case where the top portion  3 D is covered by the covering layer  5 , it is possible to improve the resistance to the abrasion that occurs with respect to the living tissue and the like at the time of rotation of the dilator  1 . 
     Next, an example of the dilator when in use will be described. 
     First, a target object is punctured with an introduction needle to form a hole. Then, after inserting a guide wire into a lumen of the introduction needle, the introduction needle is removed. 
     Next, the proximal end of the guide wire is inserted into the lumen of the dilator, and the dilator is inserted into the hole. Then, the dilator is pushed forward while rotating the shaft to expand the hole of the punctured portion. At this time, the tapered portion advances due to a screw action or the like of the spirally-arranged protruding portion due to the rotation operation of the shaft, and the hole can be smoothly expanded by the tapered portion. 
     Although embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made. 
     For example, as shown in  FIG. 3 , the covering layer  5  may cover the entire periphery of the outer peripheral surface  2 A of the first coil  2 , and the protruding portion  3 A (second coil  3 ) may be provided on the covering layer  5 . Specifically, the protruding portion  3 A (second coil  3 ) is wound around the covering layer  5  while pressing the covering layer  5  toward the inner radial direction of the first coil  2  with the protruding portion  3 A (second coil  3 ). As a result, a concave portion is formed on the covering layer  5  along the protruding portion  3 A (second coil  3 ). Further, the structure becomes one in which the protruding portion  3 A (second coil  3 ) is fitted into the concave portion. According to this configuration, because the covering layer  5  is located between adjacent parts of the protruding portion  3 A, and makes contact with the outer peripheral surface  3 C of the protruding portion  3 A, it is possible to suppress displacement of the protruding portion  3 A in the lengthwise axis direction, and to prevent pinching of the living tissue. 
     Furthermore, as shown in  FIG. 4 , the dilator  1  of the embodiment may be a dilator  10  in which the second coil  3  has gaps between adjacent parts along the axial direction of the first coil  2  up to the proximal end thereof. 
     Moreover, as shown in  FIG. 5 , the first coil  2 , which is a hollow shaft, does not have to have a distal end portion  2 E, or as shown in  FIG. 6 , may have an approximately cylindrical and hollow leading-edge portion  7 , which is formed by pouring a brazing material (a silver-tin brazing material, a gold-tin brazing material, or the like) into the distal end portion  2 E of the first coil  2 . In addition, a distal tip having the same shape as the leading-edge portion  7  may be provided on the distal end side of the tapered portion  2 D instead of the distal end portion  2 E (leading-edge portion  7 ). Also, the resin of the covering layer  5  may be provided in excess on the distal end portion  2 E or on the distal end side of the tapered portion  2 D, and a distal tip made of resin may be formed on the distal end side by the resin that has been provided in excess. Furthermore, a tip may be formed on the distal end portion  2 E or on the distal end side of the tapered portion  2 D using the resin of the covering layer  5  and a meltable resin material. 
     In addition, as shown in  FIG. 7 , a dilator  20  is also possible in which the first coil  2  is constituted by a hollow shaft  21  formed by casting or the like. The hollow shaft  21  has a hollow shape, and is formed having a lumen  21 A that passes through from the proximal end to the distal end. Furthermore, the hollow shaft  21  includes a proximal end portion  22 , a tapered portion  23 , and a distal end portion  24 , and the outer diameter increases from the distal end toward the proximal end. The material forming the hollow shaft  21  is not particularly limited as long as it ensures the softness of the tapered portion  23  and the distal end portion  24 , and is biocompatible, and examples include stainless steel, superelastic alloy materials such as nickel-titanium alloy, and synthetic resins such as polyvinyl chloride resins, urethane resins, polyolefin resins, polyamide resins, and fluorine resins. 
     Further, the second coil  3  is wound around the outer peripheral surface  21 B of the hollow shaft  21  in the same manner as in the embodiment above. That is to say, the second coil  3  is provided making direct contact with the outer peripheral surface  21 B of the hollow shaft  21 . The covering layer  5  covers the outer peripheral surface  21 B of the hollow shaft  21 , which is located in the gaps  3 B of adjacent parts of the protruding portion  3 A. That is to say, the covering layer  5  is located between adjacent parts of the protruding portion  3 A, makes contact with the outer peripheral surface  3 C of the protruding portion  3 A, and covers a part of the outer peripheral surface  3 C of the protruding portion  3 A. The top portion  3 D of the protruding portion  3 A is exposed to the outside from the covering layer  5 . 
     The covering layer  5  may cover the entire periphery of the outer peripheral surface  21 B of the hollow shaft  21 , and the protruding portion  3 A (second coil  3 ) may be provided on the covering layer  5 . Specifically, the protruding portion  3 A (second coil  3 ) is wound around the covering layer  5  while pressing the covering layer  5  toward the inner radial direction of the hollow shaft  21  with the protruding portion  3 A (second coil  3 ). As a result, a concave portion is formed on the covering layer  5  along the protruding portion  3 A (second coil  3 ). Further, the structure becomes one in which the protruding portion  3 A (second coil  3 ) is fitted into the concave portion. According to this configuration, because the covering layer  5  is located between adjacent parts of the protruding portion  3 A, and makes contact with the outer peripheral surface  3 C of the protruding portion  3 A, it is possible to suppress displacement of the protruding portion  3 A in the lengthwise axis direction, and to prevent pinching of the living tissue. 
     The dilator  20  is also provided with the covering layer  5 , which covers the outer peripheral surface  2 A of the first coil  2  located in the gaps  3 B; therefore, it is possible to suppress displacement, in the lengthwise axis direction, of the protruding portion  3 A that extends in a spiral. Because the covering layer  5  is located between adjacent parts of the protruding portion  3 A, and makes contact with the outer peripheral surface  3 C of the protruding portion  3 A, it is possible to suppress displacement of the protruding portion  3 A in the lengthwise axis direction even further. Because the top portion  3 D of the protruding portion  3 A is exposed, compared to a case where the top portion  3 D is covered by the covering layer  5 , it is possible to improve the resistance to the abrasion that occurs with respect to the living tissue and the like at the time of rotation of the dilator  1 . 
     Furthermore, the outer peripheral surface of the second coil  3 , which is closely wound on the proximal end side of the first coil  2  or hollow shaft  21 , may also be covered by a resin. 
     Moreover, in the embodiments above, although the first coil  2  was described as a hollow coil body formed from ten wires, the number of wires is not limited to ten, and may be one or more. 
     In the embodiment shown in  FIG. 7 , the surface of the hollow shaft  21  (including the portion between the shaft and the spirally-arranged protruding portion) may have various coatings. Examples of the coating include a protective film (a typical example being a plating film) on the surface of the hollow shaft  21 , and a base film for improving the adhesion between the hollow shaft  21  and the second coil  3 . 
     In the embodiments shown in  FIG. 1  to  FIG. 7 , the spirally-arranged protruding portion preferably does not constitute a blade. The dilators of the present embodiments expand a pre-formed hole in a target object (an example being the wall of a digestive tract such as a patient&#39;s stomach). Therefore, if the spirally-arranged protruding portion constitutes a blade, the living tissue on the inner surface of the hole becomes damaged. 
     Therefore, the cross-sectional shape of the spirally-arranged protruding portion (for example, the shape of the cross-section taken orthogonally to the spiral direction of the spirally-arranged protruding portion  3 A as shown in  FIG. 2 ) preferably does not have a corner portion having an acute angle on the radially outer end portion of the shaft. That is to say, the end portion preferably has a portion which is formed having, for example, a shape which contains a corner portion having an obtuse angle, or a curve (for example, a curve containing part of a circle or an ellipse).