JPH0543392B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a catheter with a biological organ dilator, and particularly to a catheter with a biological organ dilator, which is used to permanently expand a constricted part of an organ such as a blood vessel. The invention relates to a catheter with a device attached thereto.

B. Conventional technology Conventionally, for the treatment of angina pectoris and myocardial infarction, for example, it has been applied to the narrowed part of the coronary artery of a living heart.
A catheter called a PTCA (percutaneous coronary artery reconstruction) catheter may be inserted. That is,
As treatments for lesions associated with coronary artery stenosis, in addition to treatment with thrombolytic agents and the like, there is a method of mechanically removing the stenosis using a PTCA catheter.

Such a catheter generally has a balloon at its tip, and a surgical operation is performed in which the balloon is inflated after being inserted into a stenosis, and the balloon is inflated to push and dilate the stenosis, and then the catheter is removed. Although this method of surgery is relatively easy, the disadvantage is that the effect is not permanent and the tissue tends to return to its original shape over time, causing stenosis again.

As a method to improve this drawback, a shape memory alloy cylindrical body is implanted within the blood vessel (however, this implanted cylindrical body is then covered with living tissue).
A device has been proposed. For example, U.S. Pat.
There are No. 3868956 and Special Publication No. 61-6655. The former is a method in which a tube made of a shape memory alloy with a narrowed diameter is memorized in a pre-expanded state, is inserted through a catheter, heated electrically, returns to its original shape, and expands the blood vessel. It is. In the latter method, a shape memory alloy plate is molded into a cylindrical shape with the normal inner diameter of the blood vessel, processed into a thinner diameter, inserted into the desired position of the blood vessel via a catheter, and then heated using a laser beam or high-frequency induction heating method. It is heated to return it to its original shape.

However, all of these techniques involve inserting the shape memory alloy at a temperature lower than the transformation point (Af point) and then heating it above the Af point after insertion, so they cannot avoid the following drawbacks. In other words, since the shape memory alloy is in a temperature environment lower than point A when it is in the living body,
The alloy material is not yet sufficiently elastic. Therefore, it easily deforms plastically in response to external pressure,
It is insufficient to prevent restenosis. Additionally, when using a coiled alloy structure as a conventional dilator,
Due to the deformation and movement of the material due to restoration of the memorized shape, it is difficult to determine the shape and position after the action.

C. Object of the Invention An object of the present invention is to provide a catheter equipped with a dilator that can adapt to the deformation of biological organs, can be expanded and held with stable force, and is easy to insert.

D. Structure of the invention That is, the present invention has a structure in which the outer periphery is covered with a sheath,
A catheter with a living organ dilator is provided with a living organ dilator attached between the sheath and the sheath at the insertion tip side, and the catheter is inserted as the living organ dilator into a place where it acts on the living organ, and the sheath is removed. A catheter with a biological organ dilator is attached with a biological organ dilator whose strain is in the superelastic region both at the time of its action after being inserted and at the time of its installation in the sheath before insertion. It is.

Example Examples of the present invention will be described below.

1 and 2 show a catheter 1 having a shape memory alloy coil 8, which is a biological organ dilator according to the present invention.

The catheter 1 is inserted into a sheath 9 serving as an insertion jig, and the coil 8 is attached between the sheath 9 and the distal end thereof. Also,
The rear end side is a base portion 1a, and a scale 10 is attached thereto as a guide when removing the sheath 9 as described later. In addition, at the rear end position of the coil 8,
A stopper projection 11 is provided to regulate the position of the coil 8.

What should be noted here is that when the coils 8 are exposed forward from the sheath 9 as shown in the figure and act on the expanded site of the biological organ, and when the coils 8 are all located within the sheath 9 (fixed within the sheath 9), )
Sometimes the strain in the coil 8 is in the superelastic region.

That is, the coil 8 is made of, for example, Ti-Ni.
Alloys exhibit the so-called superelastic effect as shown in Figure 3, and have hysteresis properties in which the stress does not change much as shown in A or B over a wide range of strain, and they can return to their original shape without plastic deformation. are doing. Such superelasticity occurs at a temperature equal to or higher than point A of the shape memory alloy of the coil 8. Therefore, it is designed to exhibit superelasticity after being inserted into the site of action on a living organ, so it remains in the living body (temperature is above point A).
It can exhibit sufficient elasticity and can more than follow the deformation of biological organs. Therefore, the action can be maintained with stable force.

Further, even when inserted into a living body together with the catheter 1 while being fixed within the sheath 9, the coil 8
Since the coil 8 is made to exhibit superelasticity, it has already returned to its original shape before insertion, and the coil 8 is held in a state where it bites into the inner surface of the sheath 9. Therefore, there is no deformation or movement as described above, and it is easy to determine the shape and position after the action.

In order to obtain this effect, if the transformation point (point A) of the coil 8 is higher than the temperature of the living organ, for example, the body temperature (i.e., exceeds 37°C), the above-mentioned superelastic effect will not be exhibited, so point A should be The temperature is preferably 37°C or lower, and even better is 10°C to 30°C. This A-point range takes advantage of the unique property of shape memory alloys, which is flexibility at the alloy's operating temperature.

In this case, point A of the shape memory alloy used,
The larger the temperature difference between the temperature (TA ₎ and the temperature at the place of action (T=TA _−A ), the stronger the elasticity can be obtained. For this reason, A
The lower the temperature, the better, but it is usually around 10℃.

In this example, the above-mentioned point A is a value determined by measuring electrical resistance and temperature curves, as is known.

The above-mentioned control of the transformation point is achieved by combining the main component Ti.
It can be realized as desired by changing the blending ratio with Ni, the amount of additives, and heat treatment conditions.
Furthermore, this Ti-Ni alloy is a desirable material because it has excellent durability and biocompatibility (especially antithrombotic properties) in addition to the above-mentioned properties. However, this Ti-Ni alloy contains other elements such as Cu, Cr,
There is no problem even if Zn, Fe, Al, Mo, etc. are contained, but it is desirable that Ni and Ti occupy 95% by weight or more in total.

In addition, when using the coil 8 according to this example, its surface should be coated with an inert polymer such as Teflon, an antithrombotic polymer such as cardiosan, a polymer capable of sustained release of drugs such as heparin or urokinase, etc. It's okay.

Figure 4 shows the present invention in PTCA (percutaneous vascular reconstruction)
An example of application to a medical catheter is shown below.

This catheter 21 has a balloon 23 at its tip.
is provided, and a lumen (not shown) for sending (or discharging) physiological saline 4 to this balloon.
is embedded along the length of the main body. In addition, a guide wire 26 is provided in the center of the main body.
A lumen (not shown) is formed to pass through from the rear end to the front end. Furthermore, a shape memory alloy coil 8 made of, for example, a Ni-Ti alloy is attached at a position slightly rearward of the balloon 23. In this catheter, the main body 2, except for the balloon 23, is almost entirely covered by a sheath 9 made of, for example, polyurethane elastomer.

In the above, the coil 8 has a transition temperature (A) of the alloy sufficiently lower than body temperature (A≦37°C),
When acting in vivo, it exhibits superelasticity, just as it does when inserted. This is similar to the example described above.

Catheter 1 or 21 configured as above
(The following will be explained using the catheter 1.) As shown in FIG.
The catheter body 2 is inserted into the coronary artery 13 of No. 2 (however, the drawing only schematically shows the insertion state for ease of understanding), and at this time, the catheter main body 2 is guided to a predetermined site by the sheath 9.

Then, as shown in FIG. 6A, the narrowed portion 1 of the blood vessel 13 is
After inserting the catheter to position 4, the sheath 9 is pulled out a certain distance to expose the coil 8, as shown in FIG. 6B.

At this time, since the ambient temperature and the temperature inside the blood vessel 13 before inserting the coil 8 are already higher than the point A of the coil 8, the coil 8 is inserted as shown in Fig. 6A, and the temperature is operated as shown in Fig. 6B. When acting at location 14, coil 8 exhibits superelasticity. However, at the time of insertion, even if the coil 8 tries to return to its original shape, it is covered by the sheath 9 and retains its shape. Therefore, the sheath 9 can be successfully inserted while covering the coil 8. Moreover, at this time, since the coil 8 already exhibits superelasticity, when the catheter is bent before reaching the action site, the tip side of the catheter (coil 8 portion) will also be easily bent.
Insertion can be performed with good work efficiency.

Then, at the acting site, the coil 8 is restored to its original shape as shown in FIG. 6B, but this deformation (i.e., the blood vessel 13
Even if the catheter 1 is removed and only the coil 8 is left in place after expansion (increase of The coil 8 also deforms following not only the dilation of blood vessels but also the movement of the living body, and can be applied with a stable force for indwelling, making it very suitable.

Furthermore, when the coil 8 is restored as shown in Fig. 6B, the coil 8 has already been heated above point A in the state shown in Fig. 6A, so the state shown in Fig. 6B is different from that in Fig. 6A. Compared to the state (furthermore, the state before insertion), the position and length of the coil almost correspond, making it easier to determine the shape and position of the coil after action.

In addition, at the stage shown in FIG. 6B, the length of the sheath 9 to be removed can be determined using the scale 10 shown in FIG. 1 as a guide, and the indwelling position of the coil 8 can also be controlled.

FIG. 7 illustrates various biological organ dilators applicable to the present invention.

The above-mentioned coil 8 corresponds to the one shown in FIG. 7D, but there are also coils 8 that are cylindrical (FIG. 7A), rolled (FIG. 7B), irregular tubular (FIG. 7C), and high. Next coil (Fig. 7 E), leaf spring coil (Fig. 7 F),
Cage or mesh shape (Figure 7G), cone shape (Figure 7
Although not shown, a cylindrical shape made of expanded metal can also be adopted.

Although 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 variously changed. As for the material, it is preferable to use one that does not return to its original shape after transitioning to its original shape (irreversible transition), as in the above example. Furthermore, depending on the purpose of use, the transition may be reversible (it shrinks when cooled). Further, the mounting position of the shape memory alloy and its pattern are not limited to those described above. Note that the catheter of the present invention may be inserted not only into the above-mentioned narrowed portion of the blood vessel, but also into a portion where the blood vessel has become thin and is about to rupture, or may be inserted into other portions.

F. Effects of the Invention As described above, the present invention is designed so that the strain of the biological organ dilator attached to the distal end of the catheter insertion within the sheath is in the superelastic region both when the action occurs and before insertion. Can exhibit sufficient elasticity,
It can more than follow the deformation of living organs. Therefore, the action can be maintained with stable force.

Furthermore, the biological organ expander exhibits superelasticity even when inserted into a living body, so it easily follows bending, making it easy to insert, and acts while already exhibiting superelasticity. Since it is inserted into the site, there is little deformation or movement at the work site, and it is easy to determine the shape and position after operation. In other words, the biological organ dilator is designed to exhibit superelasticity even when inserted into the living body together with the catheter while attached within the sheath, so that it will not bend when it is bent before reaching the site of action. It can be easily bent to follow the curve, and has already been restored to its original shape before insertion. Therefore, it is easy to insert the living organ expander, and since the living organ expander is held in a state where it bites into the inner surface of the sheath, there is less deformation and movement as described above, and the shape and position after the action are fixed. This makes it easier to decide.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view of the catheter (however, the coil is partially exposed), FIG. 2 is a sectional view of the main part of the catheter, and FIG.
The figure is a stress-strain curve diagram of the shape memory alloy, Figure 4 is a perspective view of another catheter, Figure 5 is a schematic diagram when inserting the catheter, Figures 6A, 6B, and 6C are the catheter inserted into the blood vessel. 7A, B, enlarged cross-sectional views of each main part sequentially showing the operation of inserting the tube into the stenosis and treating the stenosis.
C, D, E, F, G, and H are perspective views of the biological organ expander. In addition, in the symbols shown in the drawings, 1, 21...
Catheter, 8... Shape memory alloy coil, 9...
Sheath, 10... Scale, 13... Coronary artery (blood vessel), 14... Stenosis part.

Claims (1)

[Claims] 1. A catheter with a biological organ dilator whose outer periphery is covered with a sheath, and a biological organ dilator is attached between the sheath and the sheath at the insertion tip side,
The biological organ expander is inserted into a place where it acts on a biological organ, and the strain at the time when the action occurs after the sheath is removed and when it is installed in the sheath before its insertion is in a superelastic region. A catheter with a biological organ dilator attached to the biological organ dilator.