JPH06121828A - Medical balloon catheter - Google Patents

Abstract

PURPOSE:To provide an anti-thrombotic treatment to prevent thrombus from forming when a balloon catheter for expanding physically a stegnosis part of a blood vessel is used. CONSTITUTION:The catheter is constituted of a shaft part 9 having the first lumen 11 penetrating in the longitudinal direction and the second lumen 12 with an apex opened in a balloon 1, a balloon provided on the apex part of the shaft part and a connecter part provided on the rear end part and the outer surface parts of the balloon and the shaft part are a two layer structure consisting of inner layers 3 and 3' of a polyamide resin and outer layers 2 and 2' of a polyurethane resin and on the outer surface thereof, a coating layer 7 of a water-insoluble polymer contg. fine heparin particles of 0.1-10mum in size is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a medical balloon catheter for physically expanding a lumen in the body, for example, a narrowed portion such as a digestive tract or a blood vessel.

[0002]

2. Description of the Related Art Conventionally, a lumen in the body such as the digestive tract,
Balloon catheters have been used to dilate stenoses in blood vessels. That is, after inserting and indwelling a catheter having an inflatable balloon at the tip of the shaft at a target site in the body, fluid is injected from outside the body through a catheter shaft by an appropriate pressurizing means, and the balloon is pressurized to a predetermined position. It is expanded by the pressure of and expands the tissue. According to this method, since tissue expansion can be treated without performing a large-scale operation, it has been applied to many cases in recent years.

In particular, a balloon catheter for expanding a stenotic portion of a coronary artery is generally called a PTCA balloon catheter and has two passages in the longitudinal direction as disclosed in, for example, Japanese Patent Laid-Open No. 54-70683. A tube having a cylindrical foldable expansion element (balloon) is provided at the distal end portion of the tube. Initially, the indication of this method is mainly in coronary arteries, in the proximal part excluding the main trunk of the left coronary artery, in the right coronary artery and in one branch lesion, calcification over a relatively limited length of 15 mm to 20 mm. The lesions were limited to lesions with a small degree. on the other hand,
Recently, the effectiveness of this method was highly evaluated, and PTCA
With the development of timely urgent support measures, the range of its adaptation has expanded greatly.

As shown in FIG. 3, the general shape of the balloon catheter used for PTCA has an outer diameter of about 1 mm.
The cylindrical balloon (1
3) is attached, and a connector portion (1) having a liquid injection port for balloon inflation and a guide wire insertion port on the near side (1)
0) is attached. The balloon (13) is for inflating a stenosis by injecting an inflation liquid, and the balloon having a different expansion outer diameter is used according to the degree of stenosis of the affected area and the inner diameter of the blood vessel before and after the stenosis. .

In the PTCA catheter, it is common to first advance a small-diameter guide wire and then guide the catheter so that it can be easily inserted into a stenosis. Is shown in FIG.
As shown in (1), there is a hole (first lumen) (11) through which the guide wire can pass from the proximal side to the distal end side. It is also possible to inject a contrast agent through this pore. Another small hole (second lumen) (12) communicates with the catheter shaft from the proximal side of the catheter to the lumen of the balloon.
Inject and pressurize the balloon inflation liquid through 2). Therefore, in order to impart the above-mentioned function, the shaft of the PTCA catheter basically has the following structure as shown in FIG.
It has a two-lumen structure. Generally, FIG. 4 (a)
As shown in FIG. 4B, the catheter shaft often has a double-tube structure of an inner tube (5) and an outer tube (4), but as shown in FIG. 4 (b), the inner lumen of the first lumen (11) is Part or
A two lumen tube with a second lumen (12) formed in the tube wall is also used.

As a material for the catheter shaft and the balloon, a synthetic resin having appropriate flexibility and torque controllability is used. In addition, the marking band (6) is used so that the position of the balloon can be confirmed under X-ray fluoroscopy.
Is often worn. Further, since a pressure of 10 atm or more is often applied when expanding the stenosis, it is necessary to select an extremely tough resin material including the balloon. For example, polyethylene terephthalate has been used as a conventionally used resin. , Polypropylene, polyethylene and the like. Further, as described above, in order to withstand the high pressure at the time of expansion, the balloon and the catheter shaft are made of the same material, so that the balloon is more firmly joined to the catheter shaft.

However, as described above, the current adaptation site has moved to a site with a higher degree of risk, and therefore, the necessary characteristics of the inflation balloon portion and the shaft portion are high pressure resistance and a narrowed portion. It is desired that the resistance during insertion of the is low. Furthermore, when the catheter is used in a coronary artery, there is a risk that minute thrombus generated on the surface of the catheter may fly to the peripheral artery and cause occlusion. Therefore, it is desirable to perform antithrombotic treatment on the surface of the catheter. ing. Therefore, in order to produce a PTCA balloon catheter having these properties with a single resin, all of the conventional materials have been insufficient.

[0008]

SUMMARY OF THE INVENTION The present invention has been made as a result of studying various balloon materials in view of such problems of conventional balloon catheters, and the object thereof is to provide sufficient pressure resistance. Another object of the present invention is to provide a structure of a balloon portion and a shaft portion which have a property of being capable of being smoothly inserted into a stenosis portion and further having antithrombogenicity on the surface thereof.

[0009]

That is, the present invention is a balloon catheter for expanding a narrowed tissue of a body lumen, wherein a first lumen penetrating in the lengthwise direction and a tip end are opened in the balloon. A shaft portion having a second lumen, a balloon provided at a distal portion of the shaft portion, and a connector portion provided at a proximal portion, and the balloon and the outer surface portion of the shaft portion are made of a polyamide resin. A coating layer having a two-layer structure consisting of an inner layer and an outer layer of polyurethane resin, and having an antithrombogenic property on the outer surface thereof,
As an example, there is provided a medical balloon catheter characterized by being provided with a coating layer of a water-insoluble polymer containing heparin fine particles having a particle size of 0.1 to 10 μm.

The balloon catheter of the present invention has the same overall structure as the conventional one shown in FIG.
As shown in (a), attach the shaft portion (9) to the outer tube (4).
When the double tube structure of the inner tube (5) and the inner tube (5) is adopted, the outer tube (4) and the balloon (1) are respectively provided with an outer layer (2, 2 ') of a polyurethane resin and an inner layer (3, 3) of a polyamide resin.
3 ') having a two-layer structure, and a coating layer having an antithrombotic property on the outer surface of the outer layer (2, 2'), such as a heparin coat layer (7)
To provide.

When a two-lumen tube is used as shown in FIG. 1 (b), an outer layer (2 ') of polyurethane resin is provided on the outer surface of the tube, and the balloon (1) is shown in FIG. 1 (a). 2), the heparin coat layer (7) is provided on the entire outer surface of the present invention. However, the present invention is not limited to these examples. Within the range of.

Examples of the polyamide resin used in the present invention include nylon 11, nylon 12, nylon 6, nylon 6,6 and polyamide elastomer, but are not particularly limited thereto. In terms of physical properties, nylon 11 or nylon 12 is preferable. Also,
It is also possible to obtain a more preferable material by blending a plurality of types of polyamide resins.

The polyurethane resin is not particularly limited as long as it is a thermoplastic polyurethane resin, but an ether type thermoplastic polyurethane composed of dicyclohexylmethane diisocyanate and polyoxytetramethylene glycol is preferable.

Various methods are known as methods for forming a coating layer having antithrombogenicity. For the purpose of the present invention, a physiologically active substance such as heparin which suppresses thrombus formation is dispersed in fine particles. A method of coating the above-mentioned polymer substance is suitable.

Next, a specific method for forming the balloon of the present invention will be described. First, using a coaxial extruder, a tubular parison (two-layer tube having a polyamide resin as an inner layer and a polyurethane resin as an outer layer) which is a material of a balloon is prepared. Next, in order to impart sufficient pressure resistance to the balloon, the parison is stretched in the length direction, and then blow molding is performed under appropriate conditions using a mold (8) as shown in FIG. Through this step, the balloon is biaxially stretched, and it becomes possible to impart high strength that can withstand the above-mentioned use conditions. Then, finally, the balloon formed by blow molding is cut at the small-diameter portions at both ends, mounted on the distal portion of the catheter shaft, and joined at both ends. The method of joining may be a method using an adhesive, but it is generally preferable to use welding.

The size of the parison varies depending on the purpose of use of the balloon catheter (the site of the body lumen) and is not particularly limited, but as an example, the PTCA catheter as described above has an inner diameter of 0.3-. 1.0 mm, outer diameter 0.6
The thickness ratio of the inner layer polyamide resin to the outer layer polyurethane resin is 20/80 to 80/20.
If the range of the polyamide-based resin layer exceeds this range, the polyurethane-based resin layer becomes too thin, and as a result, the combined effect is reduced. On the other hand, if the polyamide-based resin layer is thinner than the above range, the pressure resistance of the balloon is lowered, resulting in a loss of safety in use.

The ambient temperature in the step of stretching the parison in the lengthwise direction may be near room temperature, but preferably in the range of 20 to 40 ° C. The draw ratio is 1.5
~ 5 times, but preferably 2 to 4
Double is appropriate. Stretching under these conditions causes the polyamide resin layer to be oriented in the stretching direction, and the balloon has a biaxially oriented structure along with the subsequent blow molding to improve the physical properties, that is, the pressure resistance. It can bring about an improvement in strength.

The temperature of the parison at the time of blow molding the parison stretched in the longitudinal direction varies depending on the kind and combination of resins constituting the parison, but is usually 80 to 180.
C., preferably 90 to 120.degree. If the temperature is 80 ° C or lower, the moldability is poor because the molding temperature is too low.
If the temperature is higher than 0 ° C, depending on the type of resin, the temperature will be too high, or the temperature will be higher than the melting point, so that the molding will not be carried out sufficiently, resulting in the rupture of the balloon or the like during blow molding due to the melting of the parison. In particular, since the thermoplastic polyurethane resin generally has a lower melting point than the polyamide resin, it is difficult to form a composition having a large proportion in the wall thickness, and therefore, a combination having a small difference in melting point is preferable.

By repeating the two-step process of stretching the parison in the lengthwise direction and blow-molding twice and three times, a balloon having a predetermined wall thickness can be obtained, and the balloon at the end of the balloon is bulky. It is possible to prevent tension. The balloon thus obtained has a cylindrical shape with an outer diameter of 2 to 4 mm, and its wall thickness is 5 to 40 µ, preferably 10 to 30 µ.

Next, a specific method for forming the shaft portion (9) of the present invention will be described. As the inner tube (5) in the example of FIG. 1 (a), a polyamide resin extruded tube may be used, while the outer tube (4) of FIG. 1 (a) and the example of FIG. 1 (b). The two-lumen tube in (1) is basically formed by using a coaxial extruder as in the case of the tubular parison which is a balloon material.

It is also possible to form a tube having a single layer structure using a polyamide resin and coat the outer surface of the tube with the polyurethane resin. In this case, a solvent that can dissolve the polyurethane resin, such as acetone,
A solution is prepared with an organic solvent such as methyl ethyl ketone, cyclohexanone, dimethylformamide, N-methyl-2-pyrrolidone, etc., and the outer surface of the tube is coated with the solution, and then the solvent is removed by drying. The organic solvent that can be used is not limited to the above-mentioned ones, and may be any solvent as long as it uniformly dissolves the polyurethane resin and does not dissolve the polyamide resin, and is not limited to the above.

To increase the duration of antithrombotic properties,
Although it is desirable to make the dispersed particles of the physiologically active substance in the polymer coating layer as fine as possible, the heparin surface coating method will be described as an example of such a method. First, fine particles of heparin are dispersed in a water-insoluble polymer matrix, which is dissolved in an appropriate organic solvent, and a solution composed of the three components of the heparin fine particles, the water-insoluble polymer matrix and the organic solvent is prepared. The outer surfaces of the balloon (1) and the shaft portion (9) are uniformly coated to volatilize and remove the organic solvent. At this time, the particle size of the heparin fine particles is appropriately in the range of 0.1 to 30 μm, preferably 0.1 to 10 μm.

Although it is generally difficult to disperse heparin in the form of such fine particles, one example of the method for forming the surface layer containing the heparin fine particles in the present invention will be listed below. That is, a heparin aqueous solution having a concentration of 10 wt% is added to a precipitant (a solvent which is a nonsolvent for heparin and uses a water-soluble organic solvent) having a volume 10 times that of the aqueous solution, for example, methanol or acetone at 50 RPM. Heparin is precipitated by pouring with stirring at the above speed, and heparin is precipitated by ultracentrifugation for 10 to 60 minutes at a centrifugal acceleration of 4000 G or more and 10000 G or less. After discarding the supernatant, the same precipitant (water-soluble organic solvent) as described above was added to the obtained heparin precipitate, and the mixture was stirred and dispersed, and then 4000 to 10000 again.
The heparin particles are settled and separated by ultracentrifugation at a centrifugal acceleration of G. By repeating such a washing operation 1 to 4 times, heparin fine particles of 0.1 to 10 μm can be obtained. Finally, the supernatant liquid is discarded, and while the precipitated heparin particles are not dried, an approximately equal amount of the organic solvent as the precipitating agent, such as tetrahydrofuran, is poured to disperse the heparin in the form of fine particles, and this dispersion liquid A water-insoluble polymer that can be dissolved in the organic solvent is dissolved in to prepare a coating solution.

The water-insoluble polymer used as the matrix may be any one that can be dissolved in a suitable organic solvent and easily disperse the heparin fine particles, and examples thereof include a polyurethane resin or a polyvinyl chloride resin. Is suitable, but it is more preferable to use the same material as the polyurethane resin used for the outer layer of the balloon (1) and the shaft (9) as the matrix. The coating liquid thus obtained is coated on the outer surfaces of the balloon and the catheter shaft, and then the organic solvent is dried and removed to obtain a surface having a desired antithrombotic property.

In the balloon catheter according to the present invention, the inner layer (3, 3 ') is composed of two layers of polyamide resin and the outer layer (2, 2') is composed of polyurethane resin, and heparin fine particles are dispersed in the outermost layer. Since the heparin coat layer (7) has been formed, the occurrence of microthrombus is extremely small even when used in coronary arteries, and therefore the risk of peripheral arterial embolism due to microthrombus is small, and the treatment for stenosis can be performed safely. It becomes possible to

[0026]

INDUSTRIAL APPLICABILITY By using the balloon catheter of the present invention, when the narrowed tissue in the body is expanded, the balloon can be smoothly inserted even in a case having a severe stenosis which was difficult by the conventional method. However, the occurrence of thrombus on the surface thereof is extremely reduced, and therefore, it is possible to safely expand the indication to a higher-risk site, which is suitable as a medical balloon catheter.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a distal portion of a medical balloon catheter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a mold for producing the balloon of the present invention.

FIG. 3 is a side view showing a general shape of a balloon catheter for PTCA.

FIG. 4 is a sectional view showing a structure of a distal portion of a conventional balloon catheter.

[Explanation of symbols]

 1,13 Balloon 2,2 'Outer layer 3,3' Inner layer 4 Outer tube 5 Inner tube 7 Heparin coat layer 8 Mold 9 Shaft part 10 Connector part 11 First lumen 12 Second lumen

Claims (2)

[Claims] 1. A balloon catheter for expanding a narrowed tissue of a body lumen, comprising a shaft portion having a first lumen penetrating in a lengthwise direction and a second lumen having a tip opening into the balloon. A balloon provided at the distal portion of the shaft portion, and a connector portion provided at the proximal portion, and the outer surface portion of the balloon and the shaft portion comprises an inner layer of a polyamide resin and an outer layer of a polyurethane resin. And a coating layer having antithrombogenicity on the outer surface thereof. 2. The coating layer having antithrombogenicity has a particle size of 0.1.
The medical balloon catheter according to claim 1, wherein the medical balloon catheter is coated with a water-insoluble polymer containing 10 μm of heparin fine particles.