JP4397072B2 - Spiral balloon catheter and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spiral balloon used for treatment or diagnosis of blood vessels, vascular vessels, and other tubular tissues in the body, and a medical catheter equipped with the spiral balloon.
[0002]
[Prior art]
For the treatment of intravascular stenosis that causes myocardial infarction, angina pectoris, etc., especially coronary artery stenosis, a catheter with a balloon placed at the tip called PTCA (percutaneous transluminal coronary angioplasty) balloon catheter is used. The mainstream is to expand the constriction. This procedure will be described in more detail. First, a φ2 mm to φ3 mm catheter is guided into the aorta through a PTCA balloon catheter guiding lumen called a guiding catheter, and the tip thereof is placed at the entrance of the coronary artery. Next, a wire having an outer diameter of φ0.010 inch to 0.018 inch called a guide wire that serves as a guide for the PTCA balloon catheter is guided into the guiding catheter and passed through the coronary artery stenosis. Next, a PTCA balloon catheter having a balloon disposed at the tip is guided to the coronary artery along the guide wire, and is similarly passed through the stenosis, and the balloon is disposed in the stenosis. Then, the stenosis is forcibly opened by expanding the balloon with high-pressure physiological saline, contrast medium, or the like.
[0003]
However, this PTCA treatment method has a major problem that restenosis, that is, repeated stenosis occurs with a probability of about 40% in a short period of 3 to 6 months after treatment. Restenosis has been proven to be caused by excessive proliferation of smooth muscle cells during the healing process after the vessel wall is damaged by the forced dilatation of the vessel by the balloon.
[0004]
For this problem, it has been confirmed that the rate of restenosis can be reduced to 20% or less by placing a metal tube called a stent after balloon expansion, but this number can be further reduced from a clinical standpoint. It is an urgent need.
[0005]
Therefore, in recent years, clinical application of intravascular radiation therapy as a method for preventing restenosis has been promoted in Europe and the United States, and the results are attracting attention. In some clinical trials, the probability that restenosis will occur can be reduced to about 7%. The reason for this is said to be that cell proliferation during the healing process can be suppressed by irradiating the lesion with an appropriate dose of radiation after balloon expansion.
[0006]
Currently, there is a catheter system for intravascular irradiation treatment as a treatment system used for this purpose. This is performed after the lesion is expanded by the PTCA balloon catheter or after stent placement. More specifically, after the PTCA treatment, the PTCA balloon catheter is pulled out of the body, and then an intravascular radiation treatment catheter having a tubular tube shaft with a lumen sealed at the tip is guided and reached to the lesion. As disclosed in U.S. Pat. No. 5,1999,939, a wire having a radiation source at the tip (radiation wire) is guided to reach the lesion through the lumen of the tubular shaft with the tip sealed, and is necessary. Radiation is applied from the radiation source for a certain period of time. Generally, a dose of about 20 Gray to 30 Gray is irradiated. When irradiation is completed, the radiation wire is pulled out (collected) out of the body, and the intravascular radiation treatment catheter is also pulled out of the body to complete the treatment. In general, the radiation wire is guided and collected by remote automatic operation of a remote loader / unloader in order to prevent an operator from being exposed to radiation, and is often performed particularly in the field of cancer treatment. These are disclosed in U.S. Pat. No. 5,1999,939, U.S. Pat. No. 5,302,168, U.S. Pat.
[0007]
In recent clinical applications, there is a need for uniform irradiation of the blood vessel wall and securing of blood flow from the proximal side to the distal (peripheral) blood vessel during treatment or irradiation, that is, the need for a perfusion mechanism. It has been widely recognized. With regard to uniform irradiation of the blood vessel wall, when the radiation source is positioned at the lesion in the blood vessel, the blood vessel wall that is too close to the radiation source is excessively irradiated when it is displaced from the center of the blood vessel cross-section, necrosis of the blood vessel, This results in an aneurysm. On the other hand, a sufficient dose of radiation does not reach the blood vessel wall far from the radiation source in order to suppress smooth muscle proliferation. The reason for this is that the energy of the radiation emitted from the radiation source rapidly decreases according to the distance from the radiation source. Therefore, the intravascular radiation treatment catheter system has a so-called centering function in which the radiation source is positioned at the center of the blood vessel cross section or the center of the cross section of the stenosis, thereby providing a uniform dose to the blood vessel wall. The mechanism that can irradiate is important and is required.
Regarding another requirement, that is, ensuring the blood flow to the distal (peripheral) blood vessel, that is, the necessity of the perfusion mechanism, if the radiation to be used is β-ray, the necessary irradiation time is about 5 minutes to 10 minutes. In the case of minute and gamma rays, it takes a long time of about 10 to 30 minutes. If such a long time is required as the irradiation time, if the coronary blood does not flow to the peripheral coronary blood vessels during the irradiation, the peripheral cardiomyocytes become ischemic and cause serious symptoms such as angina. cause. Therefore, a mechanism for allowing blood to flow to the peripheral blood vessel at all times during irradiation and during centering during irradiation, that is, a perfusion mechanism, is required for the intravascular irradiation treatment catheter system.
[0008]
On the other hand, JP-A-9-507783 discloses several mechanisms for simultaneously realizing the centering function and the perfusion function. As one of the centering mechanisms, there is a spiral lobe, which is arranged by wrapping a balloon 2 around a catheter shaft tube 1 spirally as shown in FIG. As shown in FIG. 2, the radiation source 3 is guided to the tip of the tube for the catheter shaft, and the spiral balloon is inflated (expanded) so that the radiation source is positioned at substantially the center of the cross section of the blood vessel 5. It is. Since the spiral balloon has a spiral shape, blood is supplied from the proximal side to the distal side of the balloon through the groove 4 during expansion.
[0009]
However, in the case of this spiral lobe (spiral balloon), the following problems and inconveniences arise unless special measures are taken.
[0010]
The first problem is that if the thickness of the balloon after molding is constant in the circumferential direction, the balloon becomes a straight shape, not a spiral shape, in the natural expanded state of the balloon. Therefore, when the balloon is spirally wound around the catheter shaft as shown in FIG. 1 and held and fixed with an adhesive or the like, the balloon tends to return to a natural straight shape. It is difficult to fix the shaft surface at a certain position, and therefore it is difficult to fix the shaft surface at an accurate position, resulting in poor reproducibility. This is a great disadvantage in manufacturing, particularly when an adhesive having a long curing time is used. In addition, if the spiral balloon is not fixed at the correct position, that is, if there is a place where the width of the groove is too large, the accuracy of the centering tends to deteriorate, which is a serious problem in clinical practice. .
[0011]
The second problem is that when the straight balloon is fixed on the catheter shaft in a spiral state, it is necessary to forcibly twist the balloon a little. This causes stress on the balloon that causes the shaft to twist back due to the reaction. In the intravascular irradiation treatment catheter, the radiation source wire 3 passes (delivered) through the lumen, and when the shaft is twisted, the shaft lumen is deformed, so that the resistance of the radiation source when passing through the catheter lumen is reduced. It happens, or in the worst case it doesn't pass. If this happens, exposure to the patient will increase, which is a serious problem for safety.
[0012]
The third problem is that when the balloon is expanded, the balloon is strongly stressed to return to a natural straight state. When the expansion pressure is high, there is a risk that the balloon may fall off the shaft due to the stress. . These can be serious clinical problems.
[0013]
[Problems to be solved by the invention]
The present invention is to make a spiral balloon to eliminate the above disadvantages and a catheter that deploys the spiral balloon at the tip. In other words, when the balloon is expanded, it naturally has a spiral shape. This eliminates the need to spiral the balloon around the catheter shaft. Therefore, it is possible to fix it in an accurate position by an adhesive, a heat welding method, and when arranging the balloon in a spiral shape, it is not necessary to forcibly twist the balloon, and thus the shaft is not twisted by reaction, To ensure that the radiation source passes smoothly through the catheter lumen for radiation therapy at any time. Furthermore, since no stress is generated to return the balloon to a straight state even during expansion, the risk of the balloon falling off the shaft can be reduced even when the expansion pressure is high.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is characterized in that the tube of the inner cavity is formed into a balloon by blow molding, and the thickness of the balloon after molding is intentionally uneven in the circumferential direction. The maximum thickness of the balloon is made 1.3 to 8 times the minimum thickness so that the balloon exhibits a spiral shape when the balloon is expanded. If this value is less than 1.3 times, it is difficult for the balloon to show a spiral shape when the balloon is expanded. On the other hand, if this value is more than 8 times, the maximum thickness of the balloon becomes too thick and the balloon itself becomes stiff. As a result, the operability of the catheter is significantly reduced.
[0015]
In addition, as a method of manufacturing such a spiral balloon having a different thickness in the circumferential direction, first, a thermoplastic resin is extruded to obtain a “maximum thickness value” / “minimum thickness value” in the circumferential direction. A tube having a lumen that is 1.3 to 8 times, more preferably 1.5 to 5 times, is prepared, and the outer diameter after molding is 1.3 times the outer diameter of the tube. It is formed into a balloon by blow molding so as to be ˜8 times, more preferably 1.5 to 5 times. The balloon molded in this way is in an expanded state and naturally has a spiral shape, although there is a difference in degree.
[0016]
Further, the spiral balloon thus formed is attached to the distal portion of a therapeutic / diagnostic catheter having a hollow shaft tube extending to the vicinity of at least one tip, and the shaft tube is attached to a blood vessel, a pulse. The tube can be positioned at the center of the cross section of the tubular tissue in the body or at the center of the cross section at the intravascular stenosis.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, various embodiments of a spiral balloon catheter according to the present invention will be described with reference to the drawings.
[0018]
【Example】
FIG. 3, FIG. 4 and FIG. 5 show examples of the present invention, and polyurethane (Milactran E395 NAT, manufactured by Nippon Milactolan) was used as the material of the spiral balloon. Using this resin, a tube having an inner diameter / outer diameter of φ0.23 mm / φ0.40 mm was extruded. At the time of this extrusion, the die of the extrusion device and the inner pin are intentionally aligned, and the maximum value Tw-max of the wall thickness (Tw) in the circumferential direction of the tube after extrusion is 0.11 mm. The minimum value Tw-min is 0.06 mm, so that the “maximum thickness value Tw-max” / “minimum thickness value Tw-min” is 1.8 times. This is shown in FIG. This tube was biaxially stretched by blow molding as shown in Japanese Patent Publication No. 63-183070 so that the balloon outer diameter after molding was φ1.00 mm. When the thickness (Bw) of the balloon after molding was measured, the maximum value Bw-max of the thickness was 0.017 mm, the minimum value Bw-min of the thickness was 0.009 mm, and the “maximum thickness value Bw− “max” / “minimum wall thickness Bw-min” was 1.8 times, almost the same value as in the original tube. This is shown in FIG. As described above, tubes having different wall thicknesses in the circumferential direction are formed, blow-molded so as to be thin, and the balloon thickness after molding is varied in the circumferential direction so that the balloon is in an expanded state as shown in FIG. It became a spiral shape as shown in -b. This is because the stress that causes a spiral shape is caused due to uneven thickness. At this time, the thickness of the balloon near the center of the spiral shape increases. Further, the greater the value of “maximum thickness Bw-max” / “minimum thickness Bw-min”, the finer the spiral pitch. When the balloon formed this time is expanded at 6 atm, the width of the groove in the axial direction is 1 mm, and the B-ID in FIG. 3B which is the inner diameter (ID) of the spiral balloon is outside the inner shaft portion of the spiral balloon. It became almost equal to the diameter.
[0019]
As a more detailed blow molding condition described above, a tube having an inner diameter / outer diameter of 0.23 mm / 0.40 mm and a length of 25 cm, which has just been extruded, was first stretched about 2.5 times in the axial direction at room temperature. After this, a tube that has been stretched is set in a mold having a cavity having the same shape as the desired balloon shape, a stopper is plugged at one end, and a high-pressure air source is connected to the other side. In this state, the temperature of the mold was set to 50 ° C., and 8 atm of air was added to the inside of the tube to mold a balloon. Thereafter, the air pressure was set to 6 atm, the mold temperature was raised to 85 ° C., and heat treatment was performed for 2 minutes. This is to improve the dimensional stability of the balloon.
[0020]
In this example, an intravascular radiation treatment catheter was made as a medical catheter. A monorail type catheter 4 was adopted as a catheter structure for intravascular radiation irradiation treatment. This is a type in which the above-mentioned guide wire goes out of the catheter at the guide wire outlet portion 7 in the middle of the catheter 6. This is shown in FIG.
[0021]
The structure of the shaft is composed of three hollow tubes, which are a spiral balloon dilating tube 8, a guide wire passing tube 9, and a radiation source passing tube 10. These were bundled with a heat shrinkable tube 11 or a coating tube 11 to form a shaft.
[0022]
The details of the catheter assembly method will be described below with reference to FIG.
[0023]
As the spiral balloon expanding tube, a polyimide tube having an outer diameter of 0.46 mm and an inner diameter of 0.40 mm was used. The polyimide tube was cured by applying heat to a core material having an inner diameter of φ0.40 in a polyimide varnish. This was repeated soaking in the varnish and thermosetting until the outer diameter of the tube was φ0.46 mm.
[0024]
A polyethylene tube having an outer diameter of φ0.54 mm and an inner diameter of φ0.42 mm was used as a guide wire passing tube, and a polyethylene tube having an outer diameter of φ0.60 mm and an inner diameter of φ0.42 mm was similarly made by extrusion molding as a radiation source passing tube. . The length of each tube was 128 cm for the spiral balloon expansion tube, 25 cm for the guide wire passage tube, and 127.5 cm for the radiation source passage tube. In addition, when the shaft is composed only of these resins, sufficient axial push force transferability cannot be obtained from the shaft, so from φ0.30 mm to φ0.18 mm from the proximal side to the distal side. A stainless steel reinforcing wire 14 for reducing the diameter was used. These are bundled, and a heat-shrinkable tube made of polytetrafluoroethylene is arranged around the shaft on the distal and proximal sides of the shaft except for the exit portion 7 of the guide wire, and is shrunk by applying hot air And the tubes and the tube and the reinforcing wire were fixed. A plug 18 is attached to the most distal portion of the radiation source passage tube so as to prevent the radiation source from coming out of the catheter. This is very important in terms of safety as a sealed radiation source. Cyanoacrylate adhesives such as Loctite 4011 so that the proximal ends of the spiral balloon expanding tube and the radiation source passing tube constituting the proximal shaft are hermetically sealed to the Y-shaped manifold 15 port. Glued with.
[0025]
As shown in FIG. 4, the above-described spiral balloon was placed outside the tip of the shaft, and the spiral balloon 2 and the outer surface of the shaft were bonded with an adhesive 16. The spiral balloon distal end 17 was flattened so as to be airtight, and was bonded and fixed in the vicinity of the tip end of the shaft without forming a step due to a pile of adhesive or the like. The proximal end 12 of the spiral balloon is adhered or heat welded to the distal end 13 of the spiral balloon dilation tube so as to be airtight. The above-mentioned Loctite “4011” was used as the adhesive, but UV curable adhesives and urethane adhesives can also be used. Moreover, at the time of the above-mentioned adhesion, the balloon surface and the shaft outer surface were subjected to plasma treatment immediately before that. This is because the resin constituting the shaft is polyethylene, and it is difficult to adhere to this, and the adhesive strength is improved by plasma treatment. Eventually, the expanded diameter of the final spiral balloon “Dia.” Shown in FIG. 5 was φ3.1 mm.
[0026]
Although the present invention and the embodiments thereof have been described above, the technology of the present invention can be applied to many variations or other uses besides the above description.
[0027]
Polyurethane was used as the material of the spiral balloon in the embodiment, but one type of resin selected from polyamide, polyamide elastomer, polyester resin, polyester elastomer, polyolefin resin silicone, natural rubber, synthetic rubber, or 2 It may be a blend of more than one resin.
[0028]
There are several types of catheters depending on how much the guide wire passes through the catheter, such as over-the-wire type, monorail type, etc., but what is shown in this example is a monorail type. Of these, the guide wire outlet is of a type located between the spiral balloon and the manifold, but it is naturally possible for the guide wire outlet to be located on the distal side of the spiral balloon. It is natural for those skilled in the art that other than the monorail type can be applied to the over-the-wire type.
[0029]
In the embodiments, an intravascular irradiation treatment catheter for preventing coronary artery restenosis has been described. However, it is obvious to those skilled in the art that the present invention can also be applied to prevent peripheral blood vessels other than coronary arteries and dialysis shunt restenosis.
[0030]
Further, regarding the catheter system for intravascular irradiation treatment, a system that can efficiently and conveniently perform the centering function and blood perfusion to the distal side is described here. Needless to say, the present invention can be applied to all medical devices that require a centering function and a blood perfusion function in a tissue.
[0031]
【The invention's effect】
As in the present invention, by changing the thickness of the balloon in the circumferential direction, the balloon is spiraled in the expanded state, so that the molded balloon can be easily arranged spirally around the catheter shaft. In addition, accurate positioning and fixing are possible by bonding, heat welding methods, etc. Furthermore, when placing a spiral balloon, there is no need to forcibly twist the balloon, so stress is generated in the balloon that causes the shaft to twist due to reaction At any time, the radiation source will pass through the radiation therapy catheter lumen without resistance. Further, even during high-pressure expansion, there is no risk that the balloon will fall off the shaft without generating stress that tends to return the balloon to a straight state.
[Brief description of the drawings]
FIG. 1 is a view showing a state in which a spiral balloon is attached to a distal end of a catheter shaft.
FIG. 2 shows that the spiral balloon is expanded and the radiation source is centered in the cross section within the blood vessel.
FIG. 3 shows a tube before forming a spiral balloon and a balloon after blow molding.
Fig. 3a is the tube before the spiral balloon is formed.
Fig. 3b is a balloon after blow molding.
FIG. 3-c is an enlarged cross-sectional view of the balloon after blow molding.
FIG. 4 shows an embodiment of an intravascular irradiation treatment catheter to which the spiral balloon of the present invention is applied.
FIG. 4-a is a cross-sectional view in the axial direction of a catheter for intravascular radiation irradiation treatment to which the spiral balloon of the present invention is applied.
4B is a cross-sectional view taken along line AA ′ in FIG.
4c is a cross-sectional view taken along line BB ′ of FIG. 4-a.
FIG. 5 is a cross-sectional view in the axial direction of an intravascular radiation treatment catheter when the spiral balloon of the present invention is bonded to a shaft (particularly including cross-sections of balloons having different wall thicknesses).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft 2 Spiral wound balloon 3 Radiation source 4 Spiral balloon groove 5 Blood vessel 6 Intravascular radiation treatment catheter 7 Guide wire outlet 8 Spiral balloon expansion tube 9 Guide wire passage tube 10 Radiation source passage Tube 11 Heat shrink tube or coated tube 12 Proximal end 13 of helical balloon Distal end 14 of helical balloon expansion tube Reinforcing wire 15 Manifold 16 Adhesive 1 Distal end 2 of helical balloon Plug

Claims (3)

  A medical balloon formed by blow-molding a tube of a lumen, and the thickness of the balloon after molding is uneven in the circumferential direction, and the maximum thickness of the balloon is 1.3 mm, which is the minimum thickness. A medical balloon characterized in that the balloon has a spiral shape when expanded to 8 to 8 times. The spiral balloon is made of polyurethane, polyamide, polyamide elastomer, polyester resin, polyester elastomer, polyolefin resin, silicone, natural rubber, synthetic rubber, or one or more resins. The medical balloon according to claim 1, wherein the medical balloon is a blended resin . A catheter for treatment or diagnosis, which has a shaft tube with a long lumen extending to the vicinity of at least one distal end, at the center of a cross section of a blood vessel, a blood vessel, or other tubular tissue in the body, or at a stenosis in the blood vessel The medical catheter according to claim 1 or 2, wherein a balloon having a spiral shape is provided in a distal portion of the catheter in order to position the shaft tube at the center of the cross section.

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