JPH01230375A - Shape memory alloy member for medical treatment and catheter - Google Patents

Abstract

PURPOSE:To carry out the treatment of a stricture or the like (expansion treatment in particular) efficiently and to prevent the restricture of the part by making the deformation starting condition of a shape memory alloy member different at least at both ends an at the center in the longitudinal direction. CONSTITUTION:At the center of a main body 2, a lumen 7 is formed penetrating from the rear end to the front end in order to penetrate a guide wire 6, and a shape memory alloy coil 8 is installed at the position a little rear to a balloon 3. The coil 8 is made to have a relatively low transit temperature at the center 8b and a relatively high transit temperature at both ends 8a. A catheter is inserted up to a stricture of a blood vessel 13, and the balloon 13 is expanded by leading in a physiological salt solution or the like 4 to stop the flow of the blood or the humor temporarily. The physiological salt solution 10 is delivered from a leading port 11 at a constant temperature 50 deg.C, for example, the coil 8 is heated at the transit point or higher, the center 8b is expanded to the original form to expand the stricture 14, and then the expansion is transferred to both end sides gradually to expand the whole stricture 14. Then, the physiological salt solution in the balloon 3 is released, the balloon 3 is contracted, the catheter is removed, the coil 8 is left in the blood vessel, and the treatment is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a medical shape memory alloy member and a catheter, and in particular, to a medical shape memory alloy member and a catheter, and particularly to a medical device for permanently expanding a constricted part of an organ such as a blood vessel. The present invention relates to a medical shape memory alloy member used for medical purposes and a catheter equipped with the same.

Conventionally, for the treatment of angina pectoris or myocardial infarction, for example, a catheter called a PTCA (percutaneous coronary artery reconstruction) catheter is inserted into a narrowed part of the coronary artery of a living heart. There is. That is, as a treatment for lesions associated with coronary artery stenosis, in addition to treatments using thrombolytic agents and the like, there is a method of mechanically dilating the stenosis using a PTCA catheter.

These catheters generally have a plastic or rubber balloon at their tip, and after being inserted into the stenosis, the balloon is inflated.The inflation of the balloon presses and dilates the stenosis, and then the catheter is removed. It is being said. Although this method is relatively easy to treat, it has the disadvantage that the effects are not permanent and the tissue tends to return to its original shape over time, causing stenosis again.

As a method that can be used to improve this drawback, a device has been proposed in which biological organs such as blood vessels are expanded using a cylindrical body made of a shape memory alloy.For example, U.S. Patent No. 3.868,
95 (I-No. and Special Publication No. 61-6655).

Among these, the former stores the expanded state in advance -Iλ,
A cylindrical body made of a shape memory alloy with a reduced diameter is inserted through a forceps, heated 7 by an electrical method, and returned to its original shape to expand a living organ such as a blood vessel. Also,
The latter is made by shaping a shape memory alloy plate into a cylindrical shape with the normal inner diameter of the J11I tube, processing it into a thinner diameter, inserting it into the desired position of the tube through a catheter, and then heating it with a laser beam or high-frequency induction heating. It is heated using a method to return it to its original shape.

However, in the former device, the shape memory cylindrical body is heated by another heating element or the electric resistance of the shape memory alloy is heated.
Since the device itself is heated electrically using L, there is a risk of electrical leakage and electric shock, and the device is also complicated.

Furthermore, in the latter case, a device for laser beam or W hundred circular wave induction heating used in place of the former electric heating force method is not disclosed, but it is complicated and expensive.

C1 Background of the Invention Therefore, the present applicant has already proposed in Japanese Patent Application No. 62-97437 a catheter that can realize a method of dilating a stenotic area that is easy to operate and very safe to perform, without relying on the above-mentioned method. did. This catheter has a blocking part (e.g., a balloon) at its tip that has the function of arbitrarily blocking the flow of mu tubes and/or body fluids by operation from outside the body;
A cylindrical body made of a shape memory alloy which is fitted onto the catheter at the latter part of the barrier part and restores to the predetermined 1Ω bent shape at a temperature above the transition temperature; and a supply means for supplying the heating liquid to the
, is a sign of ~. That is, the shape memory alloy cylindrical body 4, which has a desired original shape memorized in advance and has been reduced in diameter, is heated by a heated liquid and returned to its original shape.

However, as a result of further examination of the effectiveness of the catheter according to the above-mentioned application, the present inventor found that although the above-mentioned excellent results were achieved, there were still points to be improved.

FIG. 12 shows the shape memory alloy coil inserted into the narrowed part of the coronary artery using the catheter described in Japanese Patent Application No. 1-4, No. 1-4, and the above-mentioned The figure shows a state in which the narrowed portion is about to be returned to its original shape, with (A) showing the coil before returning to its original shape, and (B) showing the state in which the coil is about to return to its original shape.

The pore 29 provided in the catheter 21 and its opening 29
Sending the warming liquid 10 into the coronary artery 13 via a,
An attempt is made to increase the temperature of the shape memory alloy coil 28 to a temperature higher than its original shape recovery temperature (transition temperature) to expand the diameter of the coil 28 and push out the narrowed part 14 around it.
Since both ends of 8 are free ends, both end portions 28a easily return to their original shape and expand in diameter. However, since the regions other than both end portions 28a are restrained by both end portions 28a, restoration to the original shape is not as easy as for both end portions 28a, and restoration to the original shape is delayed. When both end portions 28a of the coil come into contact with the inner circumferential surface of the coronary artery 13, this portion cannot move in the direction of the center line, and the above-mentioned restriction becomes stronger in areas other than both end portions 28a. As a result, this region is prevented from returning to its original shape due to the above-mentioned stronger restriction, and as shown in FIG. 12 (El), the coil 28 may not reach the narrowed portion 14 and may not be able to expand it.

21. Purpose of the Invention The present invention has been made in view of the above circumstances, and includes:
The object of the present invention is to provide an a-alloy member having a medical shape capable of sufficiently treating (particularly dilating) a stenosis and preventing restenosis, and a catheter using the same.

B1 Structure of the Invention The first aspect of the present invention relates to a medical shape memory alloy member in which the deformation start conditions of the shape memory alloy member are different at least at the end portion and the intermediate portion in the longitudinal direction.

Further, a second aspect of the present invention is that, in a catheter equipped with a shape memory alloy member, conditions for starting deformation of the shape memory alloy member are made different at least at an end portion and an intermediate portion in the longitudinal direction. It relates to a featured catheter.

To, Example The present invention will be explained in detail below.

1 to 4 show an example of the catheter of the present invention as a small item.

This (('IJ & Koyoru PTCA Card Wall 1 is
It has a catheter body 2 made of polyconytylene, vinyl chloride, silicone rubber, polyurethane elastomer, etc., and a balloon 3 made of elastic rubber or plastic is provided at the tip of the catheter body, and a physiological saline solution 4 is delivered to this balloon ( A lumen 5 for discharging water is embedded along the length of the main body. Also, main body 2
In the center is a lumen 7 for passing the guide wire 6.
is formed to penetrate from the rear end to the tip. Furthermore,
At a slightly rear position of the balloon 3, for example, N i-T i
A shape memory alloy coil 8 made of an alloy is removed.

The catheter, except for the balloon 3, has a sheath 9 made of polyurethane elastomer, for example.
The main body 2 is almost entirely covered by an inlet [T'l 1 +
are set up in a branched manner.

In the above, the coil 8 has the property of restoring, that is, expanding, to a pre-memorized shape at a temperature higher than the transition temperature (Af transformation point) of the alloy. Since this laminated shape memory alloy is inserted into a living body, its transition temperature is 3°C lower than body temperature.
degree or higher (especially 38°C to 48°C)
C) is preferred, and such a transition temperature can be obtained by appropriately selecting the alloy composition of the shape memory alloy. In addition, a heating liquid 10 is supplied to the coil 8 from the inlet 11 of the sheath 9 through the space between the catheter body 2 and the inner surface of the sheath 9, and examples of such heating liquid include infusion fluid, physiological saline, etc. The temperature of the liquid is selected to be at a temperature that does not cause burns, taking into account that the temperature will drop when mixed with blood and body fluids at the insertion site.

The coil 8 is made by heating the coil 8 in advance, memorizing its shape so that it has a desired expanded diameter, and then rewinding it into a thin coil shape.
Although it is attached to the outer circumference of the catheter, the outer diameter of that portion 2a of the catheter is made small so that the coil body does not slide along the catheter tube wall. Of course, instead of reducing the external size of this part, an annular soba made of silicone rubber or the like may be attached to the coil.

What should be noted here is that the coil 8 has a relatively low transition temperature at the central portion 81) and a relatively high transition temperature at both ends 8a. This will be explained in detail below.

The transition temperature of shape memory alloys differs depending on the conditions of heat treatment for shape memory even if they have the same composition.

FIG. 5 is a graph showing the relationship between holding time and transition temperature Af for heat treatment temperatures of 400°C, 1450°C, and 1500°C for Ni-'i alloy (50 atomic % Ni).

In order to provide the coil 8 with the above-mentioned transition temperature distribution, it is done as shown in FIG. A shape memory alloy wire 8 is wound around a cylindrical mold 15 at a predetermined pitch, and inserted into the furnace core tube 16. While feeding inert gas 18 into the furnace core tube 16, the center portion of the coil 8 is heated by a heater 17A. heated by. Since the central portion 8b of the coil 8 is close to the heater +7A, it is heated to a high temperature, and the heating temperature of both ends 8a of the coil 8 decreases as the distance from the heater 17A increases. Such heat treatment is applied to process the coil into a coil that matches the dimensions of the mold 15 so that the original shape and dimensions are memorized, and the coil is rewound around a catheter having a diameter smaller than this diameter to form a small diameter coil. Alternatively, the heat treatment temperature for the shape and dimensions can be kept constant to make the transition temperature uniform in each part of the coil, and a heat insulating coating can be applied to both ends, so that the time required to reach the transition temperature during use is shorter in the center. It may be made longer at both ends.

Next, these specific examples will be described.

(1) For the former method, Ni-'Fi with a diameter of 0.5 mm
Wrap an alloy wire (50 atomic% N+) around the mold to a diameter of 5 mm.
A coil was prepared and heat treated as shown in FIG. The heating temperature is 450°C at the center 8b and 5°C at both ends 8a.
00°C1 heating time is 30 minutes. This coil was wound around the catheter and re-wound into a 2.5 mm diameter coil.

(2) As the latter method, the Ni-Ti alloy wire wound around the mold in the same manner as in (1) above is heat-treated at a uniform temperature of 500'C for 30 minutes, and the wire is heated to 1.5+ from both ends.
A polyurethane solution was applied to an area with a line length of +m+ and dried to form a thin layer of polyurethane with a thickness of 0.05 uun. This coil was rewound into a smaller diameter coil in the same manner as in (1) above.

Warm water at 45° C. was flowed through these coils, and the state of shape recovery was examined, and the tendency is shown in a schematic diagram in FIG. 7. 7th
The figure (]) shows the former result, and the figure (2) shows the latter result.

As can be seen from FIG. 7, in both (1) and (2), the shape recovery starts at the center portion 8b after hot water starts flowing, and the shape recovery starts later at both end portions 8a.

This is because in (1), the heat treatment temperature of the central portion 8b is higher than that of both end portions 8a, so the transition temperature is 8
Since the temperature is low at b and high at 8a (see Figure 5), 8b reaches the transition temperature early and returns to its shape after hot water starts flowing, while 8a reaches the transition temperature later and returns to its shape. This is to make a comeback. In (2), because of the polyurethane coating layer at both ends 8a, the temperature rise is slower than that at the center 8b;
This is because it takes longer to reach the transition temperature than in the central portion 8b.

As shown in FIG. 11, the catheter 1 configured as described above is inserted from the balloon 3 side into the coronary artery 13 of the living heart 12 from the femoral artery 15, for example. (I only briefly disclosed the insertion state for this reason.) At this time, the catheter body 2 is guided to a predetermined site by the sheath 9, and this guidance is effectively achieved by the guide wire 6 described above. Further, this guidance can be monitored by observing the catheter and the alloy coil 8 with an X-ray imaging device.

Then, as shown in FIG. 8(A), the narrowed portion 14 of the blood vessel 13 is
After inserting the catheter to the position shown in FIG. 8(B), the balloon 3 is inflated by injecting physiological saline or the like 4 to bring it into close contact with the inner wall of the blood vessel, and the flow of blood or body fluid is temporarily stopped. At this time, the catheter main body 2 is moved forward by the guide wire 6 so that the coil 8 is exposed from the sheath 9 as shown in FIG. 8(A). Then,
As shown in FIG. 8(C), the physiological saline 10 is adjusted to a constant temperature of, for example, 50° C. and is fed through the introduction II] 11 of the sheath 9. The heated physiological saline 10 is introduced as shown in FIG. 4 from the inside of the sheath 9 (the outer periphery of the catheter body) and is led out to the coil 8 side. Initially, the temperature of the extracted physiological saline drops as it mixes with blood etc., but the temperature gradually rises, heating the coil 8 above the transition point, and first the central portion 8b returns to its original expanded shape. Figure 8 (
The narrowed part 14 is pushed and expanded as shown in C), and then the shape recovery is sequentially moved to both ends, and the narrowed part 14 and the area in contact with it are expanded as shown in No. 81ffl (D) (Coil 8
The state of completion of restoration to its original shape is shown in FIG. 4 by imaginary lines. ). Next, the physiological saline in the balloon 3 is drained, the balloon 3 is deflated, and the catheter is removed as shown in FIG. 8(E). In this way, the coil 8 is placed in the blood vessel with the narrowed portion 14 expanded, and the purpose of treatment can be achieved.

As described above, according to the catheter 1 of this embodiment, it is possible to dilate the narrowed part of the blood vessel and reliably prevent restenosis thereof, and the heating liquid for deforming the coil is not passed through the inside of the catheter body, but is Since the liquid is supplied through the inside of the sheath at the outer periphery, a sufficiently large passageway can be maintained, allowing the use of lower temperature hot liquid. Therefore, the operation is safe, rapid injection is possible, and the catheter body itself can be made thin (no lumen for warm fluid is required), making it easy to insert into small blood vessels such as coronary arteries. In addition, the use of a sheath makes it easier to insert the catheter.
The insertion operation can be performed reliably. Moreover, the coil 8 first expands at the center, then this expansion moves to both sides, and finally both ends 8a expand, so the return (expansion) of the coil to its original shape is not restricted in any way. , narrowing part 14
is expanded in its entirety, so there is no risk of the expansion becoming uncertain unlike the conventional method explained in Part 12.

Note that the heating of the shape memory alloy coil 8 is also different from conventional heating methods, and a heated physiological saline solution or a ring is produced. Furthermore, it is easy to adjust the heating liquid to a predetermined temperature;
It is extremely advantageous in terms of rice.

= I. If the distribution of the transition temperature as in (1) above is applied to the
In addition to the method described with reference to FIG. 6, the following method can be used to provide this information.

In Fig. 9, a cylindrical heater 17B is installed inside the furnace core tube 16, and wound around a mold inside the heater +7B (= J ke 1NIT).
i Insert the alloy wire coil (1 not shown), arrange cooling lines 19 (cooling liquid does not pass through the annularly wound tubular body) at positions corresponding to both ends of the coil, and set the coil heating temperature. An example will be shown in which the temperature distribution as described above is applied to the transition temperature as described in (1) above.

In FIG. 10, a large number of annular sheath heaters 17c (1 mm diameter) containing carbon powder are independently arranged in the furnace core tube 16,
Insert the mold 15 on which the Ni-'ri alloy wire 8 is wound into the sheathed heater 17C, and each sheathed heater +70
The power supplied to the coils was varied (large current at the center of the coil, small current at both ends of the coil), and the coil heating temperature was adjusted to the above (
An example will be shown in which the above-mentioned temperature distribution is given to the transition temperature as in 1).

In the above example (1), the heat treatment temperature is changed to give the shape memory alloy coil a predetermined transition temperature distribution, but as can be seen from Fig. 5, the heat treatment temperature is made uniform,
A predetermined moving temperature distribution can also be imparted to the coil by changing the holding time. In this case, the cooling line 19 shown in Fig. 9 may be cooled by sending a cooling liquid after a predetermined heating time has elapsed, or each heating intercostal space may be heated by a number of independent sheathed heaters +70 shown in Fig. 10. The operation may be performed by setting a predetermined time for each heater.

Also, as in the example (2) above, the transition temperature of each part of the coil is made uniform, and the time required to reach the transition temperature is shorter in the center and longer at both ends to allow for a time difference in shape recovery. can also be done as follows: For example, the wire diameter is reduced in a predetermined region on both ends of the coil to reduce the heat capacity in that region.

Inside the blood vessel, the shape memory alloy coil heats up to almost body temperature,
When it comes into contact with hot water at a temperature slightly higher than this, the areas on both ends of the coil are made into thin wires to reduce their heat capacity, so at the same time as the temperature rises, the hot water in those areas is deprived of heat and cools down. If the wire is thin, heat is absorbed by the surrounding cooled hot water, which delays the temperature rise.

This catheter can be inserted percutaneously through the femoral artery or other parts of the body, and is particularly effective in treating arteriosclerosis obliterans.

Although 1-1 the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the composition, material, shape, etc. of the above-mentioned shape memory alloy may be changed in various ways. As for the material, it is best to use one that does not return to its original shape after transitioning to its original shape (non-iT reverse transition), as in the example in j-e above, but the shape of the transition may be other than the above-mentioned coil shape, for example, a spiral network. Various choices can be made.

Furthermore, depending on the purpose of use, the transition may be reversible (it shrinks when cooled). In addition, the position and pattern of the shape memory alloy are not limited to those described above.The catheter of the present invention can be used not only for narrowing the blood vessel as described above, but also for thinning and tearing the blood vessel. It may be inserted into the site where this occurs, or it may be inserted into other sites.

1-9 As described in detail of the invention, the present invention differs in the deformation start conditions (for example, the temperature and timing of deformation start) of the shape memory alloy member at least at the end portion and the middle portion in the longitudinal direction. , the form of deformation of the shape memory alloy member (for example, the order of deformation of each part over time) can be made into a desired form. As a result, the deformation of one part of the shape memory alloy member is prevented from inhibiting or suppressing the deformation of other parts, and the entire shape memory alloy member returns to its original shape, allowing treatment of biological parts such as blood vessels. will be carried out reliably. Furthermore, when the shape memory alloy member is placed in a living body, recurrence of defects in the treated portion of the living body (for example, restenosis of blood vessels) is reliably prevented.

[Brief explanation of the drawing]

1 to 11 show embodiments of the present invention, in which FIG. 1 is a perspective view of the catheter, FIG. 2 is a sectional view of the main body of the catheter, FIG. 3 is a perspective view of the sheath, and FIG. Figure 4 is a cross-sectional view of the catheter showing the transition status of the shape memory alloy coil, Figure 5 is a graph showing the relationship between the heat treatment conditions of the shape memory alloy and the transition temperature, Figure 6 is a schematic cross-sectional view of the heat treatment furnace, and Figure 7 Figures (1) and 7 (2) are graphs showing the transition start temperature in each part of the shape memory alloy coil, and Figure 8 (A
), FIG. 8(B), FIG. 8(C), FIG. 8(D), and FIG. 8(E) sequentially show the main parts of the operation of inserting the catheter into the blood vessel and treating the stenosis. FIGS. 9 and 10 are schematic perspective views showing the inside of heat treatment furnaces according to other examples, and FIG. 11 is a schematic view when a catheter is inserted. FIGS. 121a (A) and 12(B) are enlarged cross-sectional views showing the state of transfer of the shape memory alloy and coil within a blood vessel using a conventional catheter. In addition, in the symbols shown in the drawings, 1... Catheter 2... Catheter body 3... Balloon 4... ...Physical saline 6...Guide wire 8...Shape memory alloy coil 8a...
...End portion 8b of shape memory alloy coil...
...Central part 9 of shape memory alloy coil...
・Sheath 10... Warming liquid 13... Coronary artery (blood vessel) 14...
...This is a narrowed area.

Claims (1)

[Scope of Claims] 1. A medical shape memory alloy member in which deformation initiation conditions of the shape memory alloy member are different at least at longitudinal ends and intermediate parts. 2. In a catheter equipped with a shape memory alloy member,
A catheter characterized in that conditions for starting deformation of the shape memory alloy member are different at least at an end portion and an intermediate portion in the longitudinal direction.