JPH0471543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a catheter used for capturing kidney stones and the like.

[Prior art] TiNi alloy exhibits a remarkable shape memory effect (hereinafter referred to as
(abbreviated as SME). Also,
At the same time, it is known that it also exhibits a pseudoelastic effect (hereinafter abbreviated as PE).

SME means that even if it undergoes apparent plastic deformation,
When an alloy is heated to a reverse transformation temperature (hereinafter abbreviated as Af point), it completely returns to its initial shape.

PE refers to the property that even if stress is applied at a temperature above the Af point and apparent plastic deformation is applied, the shape completely returns to its original shape as soon as the stress is removed.

Shape memory alloys such as TiNi alloy, SME, and PE are expected to be used as temperature sensors, actuators, and energy storage materials.

On the other hand, in the conventional stone capturing catheter, a stainless plate spring or a wire is used in the capturing section.

In clinical practice, when capturing a stone, a catheter is inserted near the affected area, and when the catheter reaches the stone site, a spring is used to spread the capture jig housed inside the catheter while looking through the stone using a fiber optic, etc., to capture the stone. Thereafter, the captured stone is removed from the body or destroyed inside the body using a laser or the like.

[Problems to be Solved by the Invention] However, the shapes of stones are not uniform, and there have been cases in which stones have not been successfully captured using conventional capturing jigs made of stainless steel or the like.

Therefore, the present invention has been made in view of these drawbacks,
An object of the present invention is to provide a stone capturing catheter that can reliably capture stones.

[Means for Solving the Problems] According to the present invention, there is provided a pipe that is inserted into a stone site in the body and has an open end at one end and a guide wire that moves within the pipe. , a calculus capturing section that is attached to the tip of the guide wire and is movable along the longitudinal direction within the pipe by the guide wire, and has claws that pinch and capture the calculus. In the other end of the pipe, the moving part is provided at one end of the pipe to move the calculus capturing part along the longitudinal direction of the pipe, and the moving part is supported at the other end of the pipe. a spring member having one end fixed to the wire and the other end fixed to the wire; the nail of the calculus capturing part is made of a TiNi alloy exhibiting thermoelastic martensitic transformation at least at inner parts facing each other; The claws are opened spontaneously by the elasticity of the TiNi alloy when pushed out from one end of the pipe by approaching both ends of the spring material, and by separating the ends of the spring material. As a result, a stone-catching catheter is obtained, which is drawn to one end of the pipe and securely secures the stone.

In addition, in the present invention, when using a TiNi alloy SME, a lead wire for conducting electricity is attached to the TiNi alloy part to be heated, or
When heating with a laser, a conduit is attached to guide the laser beam to the TiNi alloy portion.

[Function] The function of the stone capturing catheter of the present invention will be explained.

The stone trap is housed within the pipe until the pipe reaches the stone site. The stone capturing section has claws for pinching and capturing stones, and is attached to the tip of the guide wire. A TiNi alloy exhibiting thermoelastic martensitic transformation is used for the opposing inner parts of the claws.

When this pipe reaches the calculus site, the calculus trapping part is moved out of the pipe by moving the moving part, which has a spring material that moves the calculus trapping part in the longitudinal direction of the pipe, by bringing both ends of this spring material close together. The nail in the stone-capturing area opens spontaneously.

Once the nails have wrapped around the calculus, the spring material of the moving part is pulled apart from both ends, and the nails are pulled together with the calculus toward the pipe, ensuring that the calculus is captured. The shape memory alloy of the inner part of the claw usually has superelasticity, which makes it easier and more reliable to capture stones.

In addition, if the heating means for heating the shape memory alloy is used, when the nail is heated above the phase transformation temperature,
It recovers its shape and closes.

[Examples] The present invention will be described below based on Examples.

Embodiment 1 FIG. 1 is a sectional view showing the structure of an embodiment of a catheter for capturing stones according to the present invention.

In FIG. 1a, a trapping part 1 having a pair of claws made of a plate having a width for pinching a calculus is housed inside a stainless steel pipe. It is inserted into the body in this state up to the stone site. When the catheter reaches the calculus site, it pushes the plate spring 4 and the stainless steel plate spring 1a of the capture part 1 spontaneously expands due to the action of the spring (FIG. 1b). When the SME coil spring 1b of the trapping part 1 is heated to a temperature higher than the reverse transformation temperature by energizing or laser light while the trapping part 1 envelops the calculus, the stainless steel plate spring 1a is constricted and the calculus 5 is removed, as shown in Figure 1c. Capture.

In this embodiment, the guide wire 3 and the stainless steel plate spring 1a of the capture section 1 were made by inserting three-pronged slits into a stainless steel rod. Further, as the SME coil spring 1b, a φ3 mm helical coil spring (Af point: 50° C.) with a diameter of 0.3 mm was used. As a result, the captured stone 5 was maintained with sufficient retention force to be destroyed by the laser.

Embodiment 2 FIG. 2 shows another embodiment of a stone capturing catheter using PE of TiNi alloy.

In FIG. 2a, a trapping part 6 having a pair of claws made of a plate having a width enough to trap a TiNi alloy concretion is housed inside the stainless steel pipe 2. As shown in FIG. It is inserted into the body in this state up to the stone site. When the catheter reaches the calculus site, the plate spring 4 is pushed to cause the capture part 6 to protrude to the outside of the stainless steel pipe 2 up to the calculus 5 (FIG. 2b). and,
In the capture section 6, the PE is used to sew the stone 5 and wrap it therein to capture the stone 5 (Fig. 2c). Thereafter, when the leaf spring 4 is returned to its original position, the calculus 5 is drawn up to the stainless steel pipe 2 (FIG. 2d). In this embodiment, as shown in FIG. 2e, the TiNi alloy trap 6 is divided into three prongs,
It is mechanically fastened to the guide wire 3.
The TiNi alloy capture portion 6 is processed so that its tip is narrowed and maintains flexibility. Capture part 6
The flexible tip of the stone has the characteristic of completely returning to its original state even when bent by 5 to 6%, so it can easily pass between the stone 5 and the inner wall of a tube such as a blood vessel or urethra. Moreover, since the stress is relaxed after passing through the calculus, it can act to wrap around the calculus 5.

In this example, the TiNi alloy that is the material of the trapping part 6 has a composition of Ti-51at%Ni, and t=
A strip with a diameter of 0.2 mm and a tip of 0.1 mm (coated with polyethylene to prevent damage) was used. A stress-strain curve diagram of the example alloy at 0°C to 40°C is shown in FIG.

Here, in order to further complete the capture, the capture section 6 may be heated after capture as shown in FIG. 2c. That is, the member 6 after capture is a TiNi alloy exhibiting PE, but when the capture part 6 is heated in the state shown in FIG.
The concretion 5 is tightened by the capture part 6.

In general, stress-induced martensite occurs in TiNi alloys when they are deformed above the Af point. When this induced martensite is heated under stress, it returns to the parent phase through reverse transformation, exhibiting SME, and generating a force to return to its original shape. This effect, i.e., PE and
By using SME in combination, stone capture is more complete.

[Effect of the invention] As described above, according to the present invention, the stone capturing jig has
By using the TiNi alloy, its superelasticity allows it to adhere closely to the stone surface and capture the stone easily and reliably.

The present invention can be fully utilized not only as a catheter but also as a part of a manipulator used in a nuclear reactor or the like.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram of a catheter using TiNi alloy SME according to the present invention, and Figure 2 is a conceptual diagram of a catheter according to the present invention.
Conceptual diagram of a catheter using TiNi alloy PE,
FIG. 3 is a stress-strain curve diagram of Ti-51at%Ni alloy. 1... Capture part, 1a... Stainless steel plate spring,
1b...SME coil spring, 2...Stainless steel pipe, 3...Guide wire, 4...Plate spring for guide wire movement, 5...Calcium, TiNi alloy capture part (PE plate spring).

Claims (1)

[Claims] 1. A pipe that is inserted into a stone site in the body and has an open end on the opposite side, a guide wire that moves within the pipe, and a pipe that is attached to the tip of the guide wire. , a stone capturing catheter that is movable along the longitudinal direction in the pipe by the guide wire and includes a stone capturing section having claws for pinching and capturing the stone, the other end of the pipe includes a moving part that moves the calculus capturing part along the longitudinal direction of the pipe on one end side of the pipe, and the moving part is fixed to one end supported by the other end of the pipe and the wire. the other end of the nail of the calculus capturing portion exhibits thermoelastic martensitic transformation at least at inner portions facing each other.
The claws are made of a TiNi alloy, and when pushed outward from one end of the pipe by approaching both ends of the spring material, the claws open spontaneously due to the elasticity of the TiNi alloy, and the claws open automatically due to the elasticity of the TiNi alloy. A catheter for stone capture, characterized in that the stone is drawn to one end of the pipe by separating both ends to reliably capture the stone.