JP2000126299A - Medical dilation catheter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to be smoothly moved at a blood vessel site high in stricture and flexion by providing an elastic structure at a joining part of a dilation body and a catheter shaft or a joining part of a distal-side shaft and a proximal-side shaft, avoiding sudden change of rigidity and minimizing a level difference. SOLUTION: This catheter is obtained by precisely cut-working the thickness of a distal-side sleeve 2B and a proximal-side sleeve 2A of the dilation body 2 to be in the range of 1/5 to 4/5 of their thickness before working and externally fit-joining the sleeve 2B to a guide wire tube. In addition, the sleeve 2A is externally fit-joined to a dilation tube 4 to eliminate the discontinuity of rigidity at the joining parts to improve flexibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a percutaneous angioplasty (PTA) for dilating and treating a stenosis or an obstruction such as a coronary artery, a limb artery, a renal artery and a peripheral blood vessel.
Translumin Angioplasty or PTCA: Percutan
eous Translumin Coronary Angioplasty).

[0002]

2. Description of the Related Art A dilatation catheter used for treatment of PTA or PTCA has a dilatation body (balloon) at a distal end of a catheter shaft and is mostly made of a flexible resin. To perform the treatment, first, a guiding catheter is inserted from the femoral artery, and the distal end is positioned at the entrance of the coronary artery via the aorta. , And a dilatation catheter is inserted along the guide wire to make the dilatation body coincide with the lesion site, and a contrast agent or the like is supplied to the dilation body to dilate the dilation body. After the dilation treatment of the lesion site, the dilation body is depressurized and contracted, and the dilatation catheter is removed from the body.
The catheter shaft of such dilatation catheters generally has two lumens. One of them is
A lumen that communicates with the expansion body and allows a pressurized fluid to expand and contract the expansion body (hereinafter, referred to as an expansion lumen). The other is a lumen through which a guidewire is inserted (hereinafter, a guidewire). It is called lumen.) A manifold having a pressurized fluid supply port communicating with the expansion lumen is provided at the proximal end of the catheter shaft. Such a dilatation catheter generally has a double-tube structure in which a guidewire tube having a guidewire lumen is inserted into an expansion tube constituting an expansion lumen and coaxially arranged (coaxial type; coax
ial type) is generally used.
Some dilatation catheters are not coaxial with the dilatation tube, such as the dilatation catheter described in Japanese Patent Application Laid-Open Publication No. H10-150,086.
Incidentally, the dilatation catheter is generally an over-the-wire type in which a guide wire tube extends over the entire length of the catheter shaft in the axial direction (see FIG. 1 according to the present invention).
And the guide wire tube is 20cm
It is roughly classified into monorail type that exists only in the area of ~ 35cm.

In recent years, there has been a tendency for a dilatation catheter required to be applicable to a vascular site having a very high degree of stenosis or bending. Especially for coronary arteries with many bends,
There is a long-felt need for a PTCA dilatation catheter that allows the dilator to smoothly advance to the lesion site. For this reason, in recent years, the dilation tube has a proximal side of about 100 cm.
It is often configured with a proximal tube made of a relatively hard material at a site of ~ 135 cm and a distal tube made of a relatively soft resin material at a site of about 20 cm to 35 cm on the distal side. . This is because the degree of bending of the aorta through which the proximal tube passes is small, and the push force transmission (pussibility; Pu)
It is preferable to use a hard material in order to enhance shability, while it is preferable to use a soft resin material so that the coronary artery through which the distal tube passes has a high degree of flexion so that it can follow and deform the guide wire. . As shown in FIG. 14, the proximal tube 40A and the distal tube 40A
For bonding with B, one is often externally fitted to the other by using an adhesive or by thermal welding. The manufacturing method and joining method of these distal and proximal tubes are disclosed in Japanese Patent Application Laid-Open No. 3-207376.

However, such a conventional bonding method has the following three problems.

One is that the stiffness changes abruptly at the junction between the distal shaft and the proximal shaft, and the pushing force from the manifold connected to the proximal end of the catheter shaft is transmitted earlier than the junction. That is not done. Since the proximal tube and the distal tube are externally fitted and joined, the joint has a two-layer structure, so that it becomes very hard, and when an adhesive is used, the joint is bonded. Since it has a three-layer structure including the agent layer, it becomes even harder. Thus, the proximal tube is stiff, the junction is harder, and the distal tube is flexible, causing a stiffness abrupt change from the proximal tube to the distal tube. Therefore, when the dilatation catheter is passed through a vascular region having a high degree of stenosis or flexion, the pushing force applied from the proximal side of the catheter shaft is transmitted to the flexible distal tube ahead of the boundary where the rigidity changes suddenly. However, in the worst case, the catheter shaft is bent at the boundary. In such a case, the pushing force transmission of the dilatation catheter is extremely reduced.

The second problem is that the portion of the two-layer or three-layer structure in the joint becomes very hard, and if this portion is long, this portion has a rigidity that can easily maintain a linear shape, and is expanded. The property that the catheter bends gently along the bent blood vessel (Trackability)
Is extremely reduced. Thus, for example, when the joint tries to pass through the end of the guiding catheter, the surgeon feels resistance and causes great inconvenience.

The third problem is that since a portion having a two-layer or three-layer structure is formed at the joint, the outer diameter of the portion becomes large and a step occurs. As shown in FIG. 14, when the outer diameter becomes large and the step 41 occurs at the joint, the blood vessel wall is damaged when the dilatation catheter is pulled out, and in the worst case, the step is caught in the blood vessel wall or the guiding catheter, There is a risk that it will be difficult to even withdraw.

On the other hand, as shown in FIG. 15, a conventional expandable body (balloon) 42 includes a proximal sleeve 44A externally fitted to the distal end of an expandable tube 43, and a proximal taper portion 45A.
A distal sleeve 44B externally fitted to the distal end of the guide wire tube 46, a distal tapered portion 45B, and a straight pipe portion 47 which expands or contracts by pressurized fluid supplied through the expansion lumen 43A. Consists of Expansion tube
An adhesive or a heat welding means is used for joining the 43 to the proximal sleeve 44A and joining the guide wire tube 46 to the distal sleeve 44B. A method for manufacturing such an expanded body is disclosed in Japanese Patent Publication No. 3-37949, Japanese Patent Laid-Open Publication No. Hei 3-5746.
No. 2, JP-A-3-57463, and the like. As for the bonding, a method using heat welding is disclosed in Japanese Patent Publication No. 4-670, and a method using an adhesive is disclosed in Japanese Patent Application Laid-Open No. 6-296693.

However, in this case, the above-mentioned three problems also occur. That is, (1) Since the joint in the proximal sleeve 44A has a two-layer or three-layer structure, the rigidity changes suddenly at the joint, and the pushing force from the proximal side of the catheter shaft is reduced. It is difficult to transmit to the distal end of the dilatation catheter, and (2) if the portion of the two-layer or three-layer structure at the junction is long, the portion has rigidity that can easily maintain a linear shape, so that the curve following ability is impaired. ,
(3) The outer diameter of the joint between the proximal sleeve 44A and the distal sleeve 44B is increased and the steps 48A, 48
Since B occurs, there is a problem that the blood vessel wall is easily damaged when the dilatation catheter advances and retreats in the blood vessel. In particular, these problems have a significant effect on the ability to pass, since the junction of the dilators is more bent in the coronary arteries and passes through severely stenotic vascular sites.

[0010]

SUMMARY OF THE INVENTION In view of the above problems, the present invention seeks to solve the problem at the joint between the expander and the catheter shaft or at the joint between the distal shaft and the proximal shaft. An object of the present invention is to provide a dilatation catheter having a simple structure, a rigidity does not change suddenly, a step is minimized, and a stenosis degree and a degree of curvature can be smoothly advanced through a vascular site having a high degree.

[0011]

In order to solve the above-mentioned problems,
The present invention is a medical dilatation catheter formed by joining a plurality of tubular members and forming a catheter shaft having an expandable body at a distal end thereof, wherein one of the two tubular members is externally fitted to the other. One or both of the tubular members, including at or around the external fitting joint to be joined, is processed so as to have a thickness of 1/5 to 4/5 of the thickness before processing. It is characterized by that. Examples of the tubular member include an expansion tube and an expansion body constituting a catheter shaft.

It is preferable that the processing of the member at the outer fitting joint is performed by grinding. As a result, the thickness is accurately processed to a thickness of 1/5 to 4/5. Specifically, the processing is preferably performed by centerless (centerless) grinding.

[0013] Here, the outer shape of the member to be externally fitted and joined is:
It is desirable that the member is machined into a tapered shape whose diameter is gradually reduced toward the end of the member. Further, the arithmetic average value of the thickness at the taper start position and the wall thickness at the taper end position is calculated as the thickness before machining. More preferably, the thickness is set in the range of 1/5 to 4/5.

Specifically, the outer fitting portion externally fits one of the most proximal portion of the distal shaft having the expansion body at the distal end and the most distal portion of the proximal shaft to the other. A straight tube portion that can be the joint portion of a joined catheter shaft or that expands or contracts by the pressurized fluid, and a proximal sleeve and a distal sleeve located at both ends of the straight tube portion In the expansion body, the proximal sleeve and the distal sleeve may be the joints which are externally fitted to the catheter shaft.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of a dilatation catheter according to the present invention will be described below with reference to the drawings.
FIG. 1 is an overall side view showing an embodiment of the over-the-wire type dilatation catheter according to the present invention. In the figure, reference numeral 1 denotes a catheter shaft, and 2 denotes a catheter shaft 1.
3 shows a manifold provided at the distal end (distal end) of the catheter shaft, and 3 shows a manifold provided at the proximal end (proximal end) of the catheter shaft 1. The catheter shaft 1 has a lumen of an expansion tube 4 including a proximal tube 4A connected to the manifold 3 and a distal tube 4B joined to the expansion body 2, and a high-density polyethylene or the like having a good sliding property with respect to a guide wire. It has a double-pipe structure in which a guide wire tube 5 is disposed. At the distal end of the catheter shaft 1, the proximal sleeve 2A of the expansion body 2 is externally fitted and joined to the distal end of the distal tube 4B, and the distal end of the expansion body 2 is fitted to the distal end of the guide wire tube 5. The side sleeve 2B is externally fitted and joined. The proximal tube 4A is
The overall length is 100 cm to 130 cm and is made of a relatively hard material because of the emphasis on pushing force transmission (pushability), whereas the distal tube 4B has an overall length of 15 cm.
It is about 30 cm, and is made of a resin material which is relatively flexible so as to have a property of bending flexibly along a curved blood vessel in a coronary artery or the like. In this embodiment, the dilatation catheter in which the guide wire tube 5 and the dilation tube 4 are coaxially arranged is shown. However, in the present invention, the dilation catheter is an eccentric dilation catheter with respect to the guide wire tube. There may be. In the latter case, it becomes easier for the pressure fluid to flow through the expansion lumen between the inner surface of the expansion tube and the outer surface of the guidewire tube.

As shown in FIG. 2, the expansion body 2 includes a straight pipe portion 7 which expands and contracts by a pressurized fluid, a proximal taper portion 8A and a distal taper portion 8B, a proximal sleeve 2A and a proximal sleeve 2A. After being formed by extrusion molding or the like, the proximal sleeve 2A and the distal sleeve 2B are formed with a distal sleeve 2B by using a grinding device.
It is formed by grinding so as to have a thickness of 4/4. After the grinding process, as shown in FIG. 3, the proximal sleeve 2A is externally fitted to the distal end of the expansion tube 4 by using an adhesive or heat welding, and the distal sleeve 2B is guided. It is externally fitted and joined to the tip of the wire tube 5. As described above, the rigidity can be suppressed to a low level even at the two layers at these joints or at the three layers when the adhesive layer is present, so that the catheter shaft can be used even at a narrowed portion or a bent portion in a blood vessel. It is possible to obtain a dilatation catheter which does not bend and which is sufficient at a medical site.

Such an expanded body 2 is formed by an extrusion molding step,
It can be formed by an axial stretching molding step and a grinding step, and is a material having flexibility and high pressure resistance, specifically, nylon 66, nylon 12, “PEBAX” (A
For example, a polyamide resin such as Tochem Corporation, a polyester resin such as polyethylene terephthalate (PET) and a polyester elastomer, and a polyolefin resin are used. First, the resin material is extruded to form a tube called a parison, and placed in a mold having a cavity for forming an expansion body.
The film is stretched in the axial direction and the radial direction under a predetermined temperature environment by blow molding. In addition, the straight pipe part 7 of the expansion body, the taper part 8A,
In order to reduce the thickness of the sleeve 8B and the sleeves 2A and 2B, the axial stretching ratio may be set high. However, if the thickness of the sleeve is excessively reduced, the straight pipe 7 is not formed during the molding process. The wall thickness is also reduced at the same time, and it is not possible to give a satisfactory pressure resistance to the straight pipe portion. In addition, since there is an ultimate elongation rate peculiar to the resin, there is a point at which the resin is broken when stretched further. Therefore, there is a limit to selectively adjusting the temperature and extending only the sleeve portions 2A and 2B in the above-mentioned forming step, and the thickness of the sleeve portion is larger than the thickness of the straight pipe portion. It was easy to be very big. Therefore, when trying to secure the wall thickness of the straight pipe portion having a sufficient pressure resistance, there is a limit in reducing the thickness of the sleeve portion, and it has not been possible to obtain a thin wall portion that is sufficient in a medical field. It is.

Therefore, in the present invention, a grinding step is adopted to obtain a thin sleeve portion. In particular,
Using a centerless grinding device as shown in FIG. 4, the outer surface of an inner tube such as an expansion body is ground without supporting the axis of the tube. The tube 10 has a core material 11 for retaining its inner diameter inserted therein, and is placed on a receiving plate 12. The right side of the tube 10 is supported by the adjusting grinding wheel 13, and the left side thereof is in contact with the grinding wheel 14. In this state, both the grinding wheel 14 and the adjusting wheel 13 are rotated clockwise. Usually, the grinding wheel 14 is rotated at a higher speed than the adjusting wheel 13. The outer peripheral surface of the tube 10 rotates due to friction with the adjusting wheel 13 and is ground by the grinding wheel 14, and the grinding depth is appropriately adjusted by the feeding rotation amount of the adjusting wheel 13. Such a centerless grinding process is used to grind a tube of a relatively small diameter to a desired thickness with high precision and stability. It is most suitable for processing of a tubular member constituting a dilatation catheter to be used.

Using such a grinding apparatus, the thickness of the proximal sleeve and the distal sleeve is precisely ground to 1/5 to 4/5 of the thickness before processing. If the wall thickness is adjusted to less than one-fifth of the wall thickness before processing, a part of the joint is released by the fluid pressure introduced when expanding the expansion body, and the pressure fluid leaks out from here. On the other hand, even if the thickness is adjusted to be less than four-fifths of the thickness before processing, the step at the joint cannot be sufficiently reduced, and the rigidity suddenly changes at the joint,
Satisfactory track following cannot be obtained.

When the distal sleeve is ground, the outer shape of the distal sleeve 15 is changed as shown in FIG.
It is preferable to perform processing to form a tapered shape whose diameter gradually decreases toward the tip. At this time, it is effective to set the arithmetic mean value of the wall thickness at the taper start position 16a and the wall thickness at the taper end position 16b within a range of 1/5 to 4/5 of the wall thickness before processing. It is a target. As a result, the force transmitted from the proximal side of the catheter can be easily transmitted to the catheter distal end, and the catheter distal end has a flexible elasticity even in a stenotic part or a bent part of a blood vessel, so that the catheter smoothly advances. Becomes possible.

Next, the expansion tube 4 is connected to the above-mentioned FIG.
As shown in FIG. 6, the outer shape of the distal end of the proximal tube 4A is reduced to a thickness within a range of 1/5 to 4/5 of the thickness before processing by using the centerless grinding device shown in FIG. The diameter is reduced by grinding to increase the thickness, the inner diameter of the proximal end of the distal tube 4B is increased, and then the distal tube 4B is externally fitted to the proximal tube 4A. Here, in order to increase the inner diameter of the proximal end of the distal tube 4B, for example, a grinding wheel may be inserted into the tube bore, and the outer peripheral surface may be ground at a location where the diameter is to be increased, and may be ground. The cutting bar of the dental cutting drill may be designed according to the cutting shape, and may be inserted into the lumen of the tube for cutting. As shown in FIG. 7, the outer shape of the proximal sleeve 2A of the expansion body 2 is reduced in diameter by the centerless grinding, and the outer shape of the distal end of the distal tube 4B is reduced in diameter. The outer sleeve 4B is externally fitted to the distal end of the distal tube 4B. For these joining, when the materials of the joining members are different from each other, a cyanoacrylate-based, epoxy-based, or urethane-based adhesive can be used, and when the joining members have the same material or the same temperature characteristics, they can be thermally bonded. Welding or the like can be employed. This allows
Since there is no sudden change in rigidity at the joint, loss of the pushing force applied from the proximal side is minimized. Also,
One-fifth the wall thickness at the distal end of the proximal tube 4A
If the grinding processing is performed less than this, the joint does not have sufficient pressure resistance against the pressure fluid, and the elasticity of the joint becomes too low, so that the transmission of the pushing force to the catheter tip is rather impaired. On the other hand, even if the thickness of the distal end is reduced to less than 4/5, it is difficult to eliminate a sudden change in rigidity at the joint. In order to further continuously change the rigidity of the joint, it is preferable to dispose a core material or the like whose diameter decreases in the distal direction at least in a region including the joint.

Preferred materials for the proximal tube include polyimide, PEEK (polyetheretherketone), PET (polyethylene terephthalate), and PBT which are relatively hard, that is, have high flexural modulus and tensile strength.
(Polybutylene terephthalate), nylon, polyamide elastomer, polyester elastomer, polyurethane elastomer, polyethylene and the like. On the other hand, preferable materials for the distal tube include nylon, polyamide elastomer, polyester elastomer, polyurethane elastomer, polyethylene, etc., which are relatively soft, that is, have low bending elastic modulus and tensile strength.

An expansion tube manufactured using such a material is required to have a sufficient rigidity and pressure resistance, so that a certain thickness or more is required. Also, its outer diameter is
Since the outer diameter of the catheter shaft itself is used, it is desirable that the diameter be as small as possible. Furthermore, since a pressure fluid such as a contrast agent that expands and contracts the expandable body flows through the space between the inner surface of the expander tube and the outer surface of the guidewire tube, the inner diameter of the expander tube is reduced to such an extent that its flow path resistance does not become too large. Is preferably reduced. This is because, if the flow path resistance is large, the time required for expanding and contracting the expandable body becomes longer, and the time required for performing PTCA becomes longer, thereby increasing the burden on the patient. Therefore, the preferred inner diameter of the dilation tube is 0.65 mm to
0.95 mm, more preferably 0.72 mm to 0.90
mm, and 0.50 mm to 0.3 mm for the distal tube.
85 mm, more preferably 0.55 mm to 0.80 mm
It is. The wall thickness is preferably such that it does not easily break, and a range in which an axial tensile strength of such a degree that it is not easily cut when the dilatation catheter is pulled out is obtained.
In particular, it is desirable for the distal tube to have such a dimensional range that a sufficient curved track following property can be obtained. Therefore, the thickness of the proximal tube and the distal tube is 0.06 mm to 0.15 mm and 0.03 mm to 0.09 mm, respectively.
mm is good, but in particular, each is 0.07 mm to 0.1 mm.
2 mm and 0.04 mm to 0.07 mm are good. Therefore,
Preferred outer diameters of the proximal tube and the distal tube are 0.77 mm to 1.20 mm and 0.58 mm to respectively.
1.03 mm, more preferably 0.86 mm to 1.0
4 mm, 0.68 mm to 0.90 mm.

The guide wire tube has an inner diameter of 0.35 mm to 0.45 mm and an outer diameter of 0.50 mm.
The guide wire tube having such a dimension is desirably manufactured by an extrusion molding method using high-density polyethylene. In addition, in order to ensure good sliding properties with respect to the guide wire, 0.014 mm is required between the guide wire lumen and the guide wire.
It is desirable to provide a certain degree of clearance.

Such an expansion tube and guide wire tube can be manufactured by an extrusion method when made of a thermoplastic resin, or by a dip / cure method when made of a thermosetting resin such as polyimide. it can.

In the above-described embodiment, the over-the-wire type dilatation catheter is shown. However, the present invention is not limited to this, and can be easily applied to the above-mentioned monorail type dilatation catheter. The monorail type dilatation catheter
A guide wire tube is provided only at a portion between 20 cm and 35 cm. Further, in the above embodiment, after processing the outer shape of the joining member, this member is joined to another member. However, in the present invention, after joining the members, the outer shape of the member at the joining portion is ground. May be. In particular, in the range from the distal sleeve of the expansion body to the distal tip of the catheter, after joining the distal sleeve to the guide wire tube, as shown in FIG. In some cases, it may be preferable to grind the tape into a tapered shape.

In the above embodiment, the case where the dilatation tube is constituted by two tubes of the proximal side and the distal side has been described. However, in the present invention, the proximal side tube or the distal side tube is provided. Is further divided into three expansion tubes.
You may comprise from the above-mentioned tubular member. Further, it will be apparent to those skilled in the art that the present invention can be applied not only to dilatation catheters but also to general catheters having an external fitting joint.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, representative embodiments according to the present invention will be described in detail.

(Example) Polyimide was used as the proximal tube, and "PEBAX6333" was used as the distal tube.
SA00 ”(trademark of Atochem; Shore hardness 63)
D: Using a flexural modulus of 3,455 kgf / cm ² ), a proximal tube was prepared by dip / cure molding so that the inner diameter was 0.87 mm, the outer diameter was 1.07 mm, and the wall thickness was 0.10 mm; Disconnect the distal tube with an inner diameter of 0.74mm, an outer diameter of 0.90mm,
It was produced by extrusion molding to have a thickness of 0.080 mm. The distal tube and the proximal tube thus prepared were cut so that the total length was about 28 cm and about 120 cm, respectively. Next, a core material for maintaining the inner diameter was inserted into the lumens of these tubes, and these tubes were mounted on the above-mentioned centerless grinding device to perform a grinding process. By this grinding process, at the joint, the outer diameter of the distal end of the proximal tube is 0.97 mm,
The outer diameter of the distal end of the distal tube was 0.81 mm, and the inner diameter of the proximal end of the distal tube was 0.82 mm. The axial length of these ground portions was set to about 10 mm. After grinding, the distal end of the proximal tube was cut so that the axial length of the ground portion was 4 mm. Next, in order to externally join the distal tube to the proximal tube, the inner diameter near the junction of the distal tube proximal end should be 30 to 40 μm larger than the outer diameter of the distal end of the proximal tube. Expand so that it becomes larger. Specifically, a heating mold having an inner diameter larger than the outer diameter of the proximal end of the distal tube is disposed over the proximal end of the distal tube, and heat is applied to the proximal end. The diameter was increased by applying pressurized air to the distal tube lumen. After this expansion, the proximal end of the distal tube was cut so that the axial length of the ground portion was 4 mm. Finally, as shown in FIG. 6, the tubes were bonded together using a urethane adhesive.

The guide wire tube was made by extrusion molding using high-density polyethylene so that the outer diameter was 0.56 mm and the inner diameter was 0.42 mm. The expansion body is “Hytrel” (manufactured by DuPont; Shore hardness 7).
Using 2D), a tubular parison was extruded so as to have an outer diameter of 1.04 mm and an inner diameter of 0.52 mm, and the parison was blow-molded. The dimensions of the straight pipe at this time are
When the internal pressure is 6 atm, the outer diameter in the expanded state is 3.48 mm and the wall thickness is 0.
023mm and the dimensions of the distal sleeve are 0.76m
m, the wall thickness is 0.092mm, and the dimensions of the proximal sleeve are
The outer diameter was 1.00 mm and the wall thickness was 0.080 mm. Next, a core material for maintaining the inner diameter is inserted into the lumens of the two sleeves, and both sleeves are mounted on the centerless grinding device described above, and the outer diameter of the end of the proximal side sleeve is 0.94 mm, and the distal side is The outer diameter of the distal end of the tube was processed and adjusted to be 0.69 mm.

Therefore, after grinding, the thickness of the proximal sleeve is 0.050 mm (0.625 times the thickness before processing), and the thickness of the distal end of the distal tube is 0.057 mm (the thickness before processing). 0.62 thick
0 times). The axial length of the ground portion of the proximal sleeve and the distal tube was set to about 10 mm, and the ends were cut so as to be 1.50 mm after the grinding. Then, as shown in FIG. 7, the extension body and the distal tube are bonded to each other by using a urethane adhesive so that the axial length of the bonding portion is 1.
The sample was adhered so as to have a thickness of 50 mm to prepare a sample of the example.

The comparative example is the same as the above-described embodiment except that the grinding processing is performed. When the outer diameter of the joint of the sample of this example and the sample of the comparative example was measured with a laser measuring apparatus, it was confirmed that the sample of this example was processed with high precision and the step at the joint was extremely small.

Next, (1) “flexibility” of the tip of the catheter,
(2) Tests and evaluations on “stiffness discontinuity” at the junction between the distal tube and the proximal tube were performed.

(Evaluation of Flexibility) The flexibility of the distal end portion of the catheter was evaluated using an apparatus shown in FIG. Reference numeral 20 in the figure
Is the guide wire tube, 21 is the guide wire tube 20
, 22 denotes a distal sleeve, 23 denotes a holding device with a lifting function, and 24 denotes a force gauge. First, the distal end portion 26 of the catheter is held by the gripping means 25a at the tip of the support rod 25 connected to the force gauge 24,
The holding portion 23a, 23b of the holding device 23 with the elevating function was clamped at the distal side portion of the straight pipe portion 27 of FIG. Next, the holding members 23a and 23b were lowered at a speed of 0.5 mm / sec, and the axis 28 of the guide wire tube 20 at the distal end of the catheter was gradually inclined. FIG. 9 shows a state in which the distal end portion of the dilatation catheter is bent after a predetermined time has elapsed. At this time, support rod 25
, The load applied to the force gauge 24 was output to the XY plotter (the value in the Y-axis direction was set to the load, and the value in the X-axis direction was set to the time). In the initial state, the axis 28 of the guide wire tube 20 is kept in the horizontal direction, and the force gauge 24
Was adjusted to zero. At the same time, while measuring the load, the tip of the catheter is imaged with a CCD camera every second, and from these digital images, the guide wire tube 20 is taken.
Was measured from the horizontal direction.

FIG. 10 is a graph showing the relationship between the tip displacement angle (θ) and the load applied to the force gauge. It is evaluated that the smaller the load with respect to the tip displacement angle (θ), the higher the flexibility of the catheter tip. According to this graph, the load of the sample of the present example is about half that of the comparative example, and it can be seen that the flexibility is remarkably improved.

(Evaluation of Rigidity Discontinuity) The rigidity discontinuity at the joint between the distal tube and the proximal tube was evaluated using the apparatus shown in FIG. Symbol 30 in the figure
B is a distal tube, 30A is a proximal tube, 31 is a device having a horizontally movable function, 32a and 32b are tube holding means,
Reference numerals 33a and 33b denote force gauges connected to the tube holding means 32a and 32b, respectively. First, the holding means 32a,
Using 32b, a part 2 cm from the left end 34a of the proximal tube 30A and the right end 34b of the distal tube 30B
Between 2cm and 2cm. Next, the tube holding means 32a, which has been made movable in the horizontal direction by the device 31 having the horizontal movement function, is moved rightward in the horizontal direction at a speed of 0.5 mm / sec, and as shown in FIG. Bend in a shape. At this time, the load applied to the force gauges 33a and 33b was output to an XY plotter and measured (the value in the Y-axis direction was set to the load, and the value in the X-axis direction was set to the time). In the initial state, there is no bending at the joint, and the force gauge 33a
, 33b were set to zero. In this way, the output load of the force gauge 33a and the input load of the force gauge 33b with respect to the horizontal movement amount of the holding member 32a for each 1 mm are measured, and the value obtained by dividing the output load by the input load (load transmission rate) is obtained. The graph was obtained.

FIG. 1 shows the relationship between the moving distance and the load transmission rate.
3 is shown in the graph. As the rigidity at the joint becomes discontinuous, the load transmission rate decreases, and the transmission rate at which the pushing force applied from the proximal side (left side in the drawing) is transmitted to the distal side (right side in the drawing) is low, and the loss of the pushing force is reduced. Is large, and the discontinuity of rigidity is evaluated to be large. According to this graph, it can be seen that the sample of the example has a smaller rigidity discontinuity because the load transmission rate decreases as the bending at the joint increases, as compared with the comparative example. Especially in the comparative example, 25
When it moved by mm, it was broken.

[0038]

As described above, according to the dilatation catheter according to the present invention, the tube-like member including the outer fitting joint where one of the two tubular members is fitted to the other or the periphery thereof is included. Is processed so as to have a thickness of 1/5 to 4/5 of the thickness before processing, so that the continuity of flexibility and rigidity at the outer fitting joint is improved. Since the step is reduced, the resistance generated when the dilatation catheter is pushed into the bent blood vessel is extremely reduced, and the blood vessel can be easily passed through even a vascular region having a large degree of stenosis. It is possible to significantly improve the pushing force transmission property and the curve following ability.

Further, by employing grinding for the processing of the tubular member, it is possible to perform the processing with high precision and in a short time, and it is possible to further enhance the transmission of the pushing force and the followability of the curved path. .

Further, the outer shape of the member to be externally fitted and joined is processed into a tapered shape whose diameter is gradually reduced toward the end of the member, so that a step at the externally fitted joint is eliminated, so that the catheter can remove a blood vessel wall or the like. It is possible to smoothly advance and retreat in the blood vessel without being damaged.

[Brief description of the drawings]

FIG. 1 is an overall side view showing an embodiment of an over-the-wire type dilatation catheter according to the present invention.

FIG. 2 is a schematic sectional view showing an expansion body according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a state where an expandable body according to the present invention is joined to a catheter shaft.

FIG. 4 is a schematic front view showing a centerless grinding device.

FIG. 5 is a schematic sectional view showing a distal end portion of the dilatation catheter according to the present invention.

FIG. 6 is a schematic sectional view showing a joint between a distal tube and a proximal tube according to the present invention.

FIG. 7 is a schematic sectional view showing a joint between the distal tube and the expansion body according to the present invention.

FIG. 8 is a schematic diagram showing the configuration of an apparatus for evaluating the flexibility of the distal end portion of a catheter.

9 is a schematic diagram showing a state in which the amount of influence on the deformation angle of the catheter tip is measured using the device shown in FIG. 8;

FIG. 10 is a graph showing a relationship between a tip deformation angle (θ) and a load applied to a force gauge.

FIG. 11 is a schematic diagram showing a device configuration for evaluating discontinuity in rigidity at a joint between a distal tube and a proximal tube.

FIG. 12 is a schematic diagram showing a state in which a load transmissibility with respect to bending of a joint is measured using the device shown in FIG. 11;

FIG. 13 is a graph showing a relationship between a moving distance of a tube holding member and a load transmission rate.

FIG. 14 is a schematic cross-sectional view showing a joint between a conventional distal tube and a proximal tube.

FIG. 15 is a schematic cross-sectional view showing an expansion body provided at a distal end of a conventional catheter shaft.

[Explanation of symbols]

1 Catheter shaft 2 Expansion body 2A Proximal sleeve 2B Distal sleeve 3 Manifold 4 Expansion tube 4A Proximal tube 4B Distal tube 5 Guide wire tube 7 Straight tube 8A Proximal taper 8B Distal taper Part 10 Tube 11 Core material 12 Receiving plate 13 Adjusting grinding wheel 14 Grinding wheel 15 Distal sleeve 16a Taper start position 16b Taper end position 17 Tip tip 20 Guide wire tube 21 Expansion body 22 Distal sleeve 23 Holding with lifting function Apparatus 24 Force gauge 25 Support rod 25a Grasping means 26 Catheter tip 27 Straight tube 28 Guidewire tube axis 30A Proximal tube 30B Distal tube 31 Device with horizontal movable function 32a, 32b Tube holding means 33a, 33b Force gauge 34a Joint left end 34b Joint right end 40A Proximal tube 40B Distal tube 41 Step 42 Expansion body 43 Expansion tube 43A Expansion lumen 44A Proximal sleeve 44B Distal sleeve 45A Proximal taper 45B Distal taper 46 Guide wire tube 47 Straight pipe 48A, 48B Step

Claims (7)

[Claims] 1. A medical dilatation catheter comprising a plurality of tubular members joined to form a catheter shaft having an expandable body at a distal end thereof, wherein one of the two tubular members is connected to the other. One or both of the tubular members, including at or around the outer fitting joint to be fitted and joined, is one fifth to four fifths of the thickness before processing.
A medical dilatation catheter processed so as to have a thickness. 2. The medical dilatation catheter according to claim 1, wherein the processing of the member at the outer fitting joint is performed by grinding. 3. The medical dilatation catheter according to claim 2, wherein the processing of the member at the outer fitting joint is performed by centerless (centerless) grinding. 4. The medical dilatation catheter according to any one of claims 1 to 3, wherein the outer shape of the member to be externally fitted is processed into a tapered shape whose diameter is gradually reduced toward an end of the member. . 5. The arithmetic mean value of the thickness at the taper start position and the thickness at the taper end position of the member processed into the tapered shape is one fifth to four fifths of the thickness before processing. The medical dilatation catheter according to claim 4, which is set within the range. 6. The outer fitting joint is formed by externally joining one of a most proximal portion of a distal shaft having the expansion body at a distal end and a most distal portion of a proximal shaft to the other. The medical dilatation catheter according to any one of claims 1 to 5, which is the joint of the catheter shaft. 7. The expansion body includes a straight pipe portion expanded or contracted by the pressurized fluid, and a proximal sleeve and a distal sleeve located at both ends of the straight pipe portion.
The medical dilatation catheter according to any one of claims 1 to 6, wherein the joint formed by externally fitting the proximal sleeve and the distal sleeve to the catheter shaft is the externally fitted joint.