Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Reexamination Certificate
1998-06-15
2001-01-23
Snow, Bruce (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S001150
Reexamination Certificate
active
06176873
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a stent for an endoscope.
When a biliary stricture occurs, a biliary duct is narrowed to cause a clogging in a biliary duct. In such case, the flow of a bile is prevented, which may cause an icterus.
A stent is used to treat a stricture including the above mentioned biliary stricture. The stent is carried by an endoscope and inserted into a narrow portion of the annular organ (such as a biliary duct), thereby to widen the narrow portion. The stent is left in the narrow portion of the annular organ.
A conventional stent includes an expandable tube (for example, a mesh tube made of steel wires). When the stent is inserted into the annular organ, the expandable tube expands thereby to widen the narrow portion of the annular organ.
However, such conventional stent has a disadvantage such that, once the stent is left in the annular organ, it is difficult to remove the stent from the annular organ.
Further, a recently developed stent has projections which engage a surface of the annular organ, so as to prevent the stent from slipping out of the annular organ. It is further difficult to remove such stent from the annular organ.
In some cases, it is necessary to replace the stent with new one (particularly when the stent is clogged). Thus, there is strong demand of a stent which can be easily removed from an annular organ.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a stent which can be easily removed from an annular organ.
According to an aspect of the present invention, there is provided a stent including a mesh tube so constituted that a diameter thereof is contracted when axially extended, while the diameter thereof returns to its original diameter when not axially extended. A cap is provided to a first axial end of the mesh tube for bundling the first axial end thereof. The cap has a through hole which connects an interior and an exterior of the mesh tube. A tail tube is provided to a second axial end of the mesh tube so that the tail tube and the mesh tube form a continuous path. The tail tube bundles the second axial end of the mesh tube.
On inserting the stent into an annular organ, a pusher tube is inserted through the continuous path (the tail tube and the mesh tube) so that the tip of the pusher tube abuts the cap. When the cap is pushed by the pusher tube, the mesh tube is extended in axial direction. With this, the diameter of the mesh tube can be contracted. Further, during the insertion of the stent into the annular organ, the mesh tube is axially extended due to the force applied by the pusher tube and a friction between the mesh tube and the annular organ. That is, the diameter of the mesh tube is contracted during the insertion of the stent. Thus, the stent can be smoothly inserted into the annular organ.
Further, as constructed above, the stent can be removed from an annular organ by pulling the tail tube. Thus, the stent can be easily removed from the annular organ.
In a particular arrangement, the tail tube has a catch hole formed at a certain distance from the mesh tube. With this, it is possible to hook the catch hole (using a hooking device or the like) and to pull the tail tube. Thus, the stent can be further easily removed from the annular organ.
It is preferred to provide a string to the tail tube. One end of the string is fixed to the tail tube, while the other end of the string is a free end. Optionally, a knot can be formed on the free end of the string. With this, it is possible to hook the knot (using a hooking device or the like) and to pull the string. Thus, the stent can be further easily removed from the annular organ.
Preferably, the cap includes an inner ring portion and an outer ring portion. The inner and outer ring portions are so constituted that a periphery of the first axial end of the mesh tube is sandwiched between the inner and outer ring portions. Optionally, it is possible to provide a connecting ring for connecting the mesh tube and the tail tube. Further, an inner diameter of the cap is smaller than an inner diameter of the tail tube. With this, when the pusher tube is inserted through the tail tube and the mesh tube, the tip of the pusher tube abuts a surface around the through hole of the cap.
According to another aspect of the present invention, there is provided a stent including a mesh tube so constituted that a diameter thereof is contracted when axially extended, while the diameter thereof returns to its original diameter when not axially extended. A cap is provided to a first axial end of the mesh tube for bundling the first axial end thereof. The cap has a through hole which connects an interior and an exterior of the mesh tube. The mesh tube is bundled at a second axial end thereof. A string is provided to the second axial end.
Accordingly, it is possible to remove the stent from the annular organ by pulling the string. Thus, the stent can be easily removed from the annular organ.
In a preferred embodiment, one end of the string is fixed to the tail tube, while the other end of the string is a free end. Further, a knot is formed on the free end of the string. With this, it is possible to hook the knot (using a hooking device or the like) and to pull the string. Thus, the stent can be further easily removed from the annular organ.
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Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Snow Bruce
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