JP2006181258A - Manufacturing method of microcatheter and microcatheter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable method of manufacturing a microcatheter with good workability and the manufactured thin-diameter microcatheter consisting of an inner layer, a reinforcement layer, and an outer layer. <P>SOLUTION: In the method of manufacturing a microcatheter consisting of an inner layer, a reinforcement layer, and an outer layer, the reinforcement layer has a braided structure, and at least one wire of the braided structure, which is coiled in one direction of the microcatheter composed of wires with different melting points, is melted by heating and then coated with the outer layer to obtain the manufactured thin-diameter microcatheter and good workability. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a microcatheter inserted into a thin peripheral blood vessel and a microcatheter for the diagnosis or treatment of blood vessels and organs such as the brain, heart, and abdomen.

  Conventionally, a medical act of percutaneously inserting a catheter inserted into a blood vessel into an organ such as the brain, heart, or abdomen, and administering and injecting a therapeutic agent, an embolic substance, a contrast agent, or the like has been performed. In recent years, due to advances in medicine, it has become necessary to inject therapeutic agents, embolic substances, contrast agents and the like into finer peripheral blood vessels, and the development of microcatheters that can be inserted into these fine peripheral blood vessels has been desired. Since microcatheters need to be surely advanced by a surgeon's operation through a slender peripheral blood vessel, various operability is required. This operability includes pushability that reliably transmits the operator's pushing force to the tip of the microcatheter, and torque transmission that reliably transmits the rotational force applied by the operator to the tip of the microcatheter. The guide wire follows the guide wire that passes through the lumen of the microcatheter and travels in the bent blood vessel, and the kink resistance that does not cause the micro catheter to be bent even at the bent or curved portion of the blood vessel is raised. . In order to realize these operability, it is well known that the tip (distal side) of the microcatheter is made of a flexible material and the end (proximal side) is made of a hard material. In order to secure kink resistance and pushability, a reinforcing layer having a braided structure or a coil structure is also used in many microcatheters.

However, although the kink resistance and pushability can be ensured by configuring the reinforcing layer, for example, when the braided structure is taken, it is difficult to reduce the diameter of the microcatheter because the wires constituting the braid overlap. Flexibility is difficult to secure. When the coil structure is adopted, the coils do not overlap, making it easier to reduce the diameter than the braided structure and the flexibility of the tip is good. There was a drawback that the handling property in the process such as coating was poor. Also, continuous production, which is easy with a tube with a braided structure, was difficult with a tube with a coil structure. As a method for solving these problems, for example, Patent Document 1 discloses a structure in which a right-handed coil and a left-handed coil are laminated. Although this method improves torque transmission and pushability and improves handling in the process, it is difficult to reduce the diameter of the microcatheter, which is an advantage of the coil structure. In Patent Document 2, the proximal side is a braided reinforcing layer, and the distal side is a saddle shape (coil shape) made of a single metal wire. The proximal portion is relatively rigid and the distal portion is flexible and flexible. The sex is high. However, this method inevitably reduces the strength at the joint surface between the braided reinforcing layer and the coil, and the manufacturing method is complicated.
Japanese Patent Laid-Open No. 9-149938 JP 2000-176021 A

  An object of the present invention is to provide a manufacturing method and a microcatheter that can easily and stably manufacture a microcatheter having good operability and a small diameter, which is the above-mentioned problem.

As a result of earnest research to solve the above problems, the present inventor,
The reinforcing layer has a braided structure, and the braid is composed of strands of materials having different melting points, and at least one strand wound in one direction has a melting point T _mfl ( ° C), the remaining strand wound in the same direction as the strand made of the resin, and the strand wound only in the other direction intersecting the one spiral strand are melting point T _{It consists of} a resin or metal of _mfh (° C.) or higher, and the melting points T _mfl (° C.) and T _mfh (° C.) of the strands are _expressed using the melting point T _mo (° C.) of the resin constituting the outer layer:
T _mo +20 <T _mfl <350 and T _mfl <T _mfh
In a method for producing a microcatheter represented, by heating at a temperature below the portion of the microcatheter T _mfl (° C.) or higher T _mfh (° C.), wire made of a resin having a melting point T _mfl (° C.) It was found that operability can be greatly improved and a small-diameter microcatheter can be stably produced by including a step of melting at least a part of the coating and then coating the outer layer.

In the method of manufacturing a microcatheter, the present invention also provides that all of the spirally wound strands constituting the braided structure are represented by the formula: T _mo +20 <T _mfl <350 and the formula: T _mfl <T _mfh . It is characterized by comprising a resin _having a melting point T _mfl (° C.).

Further, by heating at a temperature below the portion of the distal side of the microcatheter T _mfl (° C.) or higher T _mfh (° C.), thereby melting at least a portion of the wire made of a resin melting point T _mfl (° C.) Characterized in that it includes a step, followed by coating the outer layer.

  The present invention is characterized in that a part of the distal side of the microcatheter is in a range of 1000 mm from the tip of the microcatheter.

  As described above, the present invention relates to a microcatheter and a method for manufacturing the microcatheter.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a microcatheter which can provide the softness | flexibility of a front-end | tip with a small diameter while maintaining favorable operativity and a microcatheter can be provided.

  The microcatheter manufacturing method and microcatheter of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an overall view of a microcatheter to which the present invention is applied. The microcatheter of this embodiment has a catheter body 1 composed of an inner layer, a reinforcing layer, and an outer layer, a marker 2 attached to the distal side of the catheter, and a hub 3 provided at the proximal end of the catheter body.

  In the present invention, the resin constituting the inner layer is not particularly limited. For example, polytetrafluoroethylene, polytetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene, tetrafluoroethylene / ethylene copolymer, etc. Examples include fluororesins, polyolefins such as polypropylene and polyethylene, nylons 6, nylon 66, nylon 12, polyamides such as polyamide elastomer, polyethylene terephthalate, polyester elastomer, polyurethane, polyurethane elastomer and the like.

The braided layer, which is a reinforcing layer, is composed of strands made of a material having different melting points that are wound. Among the strands constituting the braid, at least one of the strands wound in one direction has the formula:
T _mo +20 <T _mfl <350 and T _mfl <T _mfh
In has become a resin having a melting point T _mfl (° C.) represented, and the rest of the wire wound around the wire in the same direction made of the resin, all the wires that are other Nishimaki the formula :
T _mfl <T _mfh
It is made of a resin or metal _having a melting point T _mfh (° C.) or higher expressed by:

Examples of resins _{having a} melting point T _mfl (° C.) include polyolefins such as polypropylene and polyethylene, nylons 6, nylon 66, nylon 12, polyamides such as polyamide elastomer, polyesters such as polyethylene terephthalate and polyester elastomer, polyurethane, polyurethane Examples include elastomers, and these materials may be combined depending on the desired mechanical properties. Examples of resins having a melting point T _mfh (° C.) or higher include polyolefins such as polypropylene and polyethylene, nylon 6, nylon 66, nylon 12, polyamides such as polyamide elastomer, polyesters such as polyethylene terephthalate and polyester elastomer, polyurethane, Polyurethane elastomers, aramids, polyarylates, etc., examples of metals include stainless steel or highly radiopaque materials such as tungsten, platinum, iridium, gold, etc. Desirable mechanical properties and radiopacity These materials may be combined.

  Examples of resins constituting the outer layer include nylons 6, nylon 66, nylon 12, polyamides such as polyamide elastomer, olefins such as polyethylene, polypropylene, polymethyl methacrylate, and modified polyolefin, polyethylene terephthalate, polybutylene terephthalate, and polyester elastomer. Examples thereof include polyesters, polyurethanes, polyurethane elastomers, polymer blends and polymer alloys thereof.

The constituent material of the inner layer, the reinforcing layer, and the outer layer can be used in any combination from these resins and metal materials, but the strands of the wire wound in one direction constituting the braided layer that is the reinforcing layer It is necessary to select a resin having a melting point T _mfl (° C.) for at least one, and it is necessary to select a resin or a metal having a melting point T _mfh (° C.) or more for all the other wound wires. The resin material may contain various additives such as a contrast agent, a plasticizer, a reinforcing article, and a pigment in addition to the polymerization aid used at the time of polymerization.

  The shape of the wound wire constituting the braid of the reinforcing layer may be a round wire having a circular cross section or a flat wire having a square cross section. A round wire is preferred when two or more wires are wound. The diameter of the round wire may be 0.10 mm or less, preferably 0.01 mm or more and 0.05 mm or less, and the thickness of the flat wire may be 0.1 mm or less, but is preferably 0.01 mm or more and 0.05 mm or less. If the diameter of the round wire and the thickness of the flat wire are 0.10 mm or more, the microcatheter becomes thick and sufficient flexibility cannot be obtained. If it is less than 0.01 mm, it may be frequently cut in the braiding process, and the operability such as kink resistance and pushability of the microcatheter may be lowered.

At least one strand made of a resin _{having a} melting point T _mfl (° C.) may be selected. One is spirally wound with two or more strands, at least one of which is made of a resin having a melting point T _mfl (° C), and the remaining strand and the other spiraled strand are the melting point T _mfh (° C) If having the above resin or a metal (2, 3), after taking the braided structure by general braiding step performed is heated at T _mfl below (℃) or T _mfh (℃) temperature. By being heated to T _mfl (° C.) or more and less than T _mfh (° C.), part or all of the strand made of resin _having a melting point T _mfl (° C.) is melted. Resin of the molten melting point T _mfl (° C.) is embedded in the gap of the wire that is configured on the other melting T _mfh (° C.) or more resins or metal. By eliminating some of the strands that make up the braided structure, it becomes a structure that has both the characteristics of the braided structure and the coil structure, so pushability, torque transmission, etc. that are the operability required for microcatheter While ensuring the operability, it is possible to give the tip flexibility and the diameter reduction of the microcatheter.

Further, since the resin melting point T _mfl (° C.) is embedded in the gap of the wire composed of a molten other melting T _mfh (° C.) or more resins or metal, the outer layer sheath of the microcatheter of the prior braided structure Then, the problem that it was difficult to coat the outer layer resin smoothly and thinly due to surface irregularities caused by braiding is also solved.

In the present invention, the heating method is not particularly limited, but in order to obtain a good molded state after heating and melting, a tube having the braid (hereinafter referred to as an intermediate tube) is covered with a heat-shrinkable tube, and T _mfl (° C.) or higher. A method of removing the heat-shrinkable tube after heating at a temperature below T _mfh (° C.) is preferred. A part or all of the strands made of a resin _{having a} melting point T _mfl (° C.) is melted by heating at a temperature of T _mfl (° C.) or more and less than T _mfh (° C.), solidified by cooling, and then the outer layer is coated. The melting point T _mo (° C) of the outer layer resin is the formula:
T _mo +20 <T _mfl
Since the strand made of the resin having the melting point T _mfl (° C.) is not melted by the heat received by the intermediate tube when the outer layer is coated, the above-described excellent characteristics can be maintained.

As another form of the microcatheter that can be used in the present invention, one is _{wound with} one strand made of a resin of T _mfl (° C.) (FIG. 4), or is wound with two or more strands. And when all of one strand is comprised with resin of melting _| fusing point _Tmfl ( _degreeC ) (FIG. 5, FIG. 6), after taking a braided structure by the generally performed braiding process, as mentioned above, _Tmfl ( (° C.) By heating at a temperature not _lower than T _mfh (° C.), part or all of the strand made of resin _having a melting point T _mfl (° C.) is melted. Resin of the molten melting point T _mfl (° C.) is embedded in the gap of the wire that is configured on the other melting T _mfh (° C.) or more resins or metal. At the same time, a strand made of a resin _{having a} melting point T _mfl (° C) melts, and the winding force of the other strand made of a resin _having a melting point T _mfh (° C) or more causes the strand to move to the inner layer side. Can move. As described above, when one strand is melted and the other strand moves to the inner layer side, it is possible to realize a smaller diameter than the braided structure. Furthermore, since one of the strands is melted, a pseudo-coil structure can be formed, so that the flexibility of the tip can be improved. Since one of the strands has a braided structure until it melts, the handling property before coating the outer layer is better than that having a coil structure without any pitch deviation.

The wire made of a resin melting point T _mfl (℃) from the tip of the microcatheter to the proximal end relative to the full-length which is subjected to braided structure, at a temperature below T _mfl as described above (℃) or T _mfh (℃) Although it can be heated and melted, as described below, only a part of the microcatheter can be selectively heated to melt only a part of the strand made of a resin _having a melting point T _mfl (° C.). Only distal intermediate tubes subjected to braid is heated at T _mfl below (℃) or T _mfh (℃) temperature, the other portion so as not to heat. Thereafter, by coating the outer layer, a microcatheter having a pseudo-coil structure on the distal side and a braided structure on the proximal side can be easily manufactured. At the boundary portion between the pseudo coil structure and the braided structure of the microcatheter manufactured by the manufacturing method of the present invention, the strands made of resin _having a melting point T _mfl (° C.) are heated and radiated by heating to generate unmelted portions and molten portions. Changes continuously, and there is also an effect that there is no locally weak portion. It is preferable that the part to be heated is a part within a range of 1000 mm from the distal end of the distal microcatheter. From the viewpoint of improving pushability, it is more preferable to be part of the range of 500 mm from the tip.

According to the present invention, by being embedded in the gap between the strands of the resin of the molten melting point T _mfl (° C.) it is configured in the other melting T _mfh (° C.) or more resins or metal, and molten in the prior art Since the resin is embedded in the gap between the spirals where the resin does not melt, it is possible to suppress the opening of the braid, which is a problem with the cut surface of the braided tube.
As described above, by changing the ratio of the strands consisting of a melting point T _mfl made of a resin (℃) strand and the melting point T _mfh (℃) or more resins or metal, micro having various excellent operability A catheter can be obtained.

In the present invention, the outer layer may be coated by extrusion or may be shrunk using a heat shrinkable tube. A method for forming the inner layer, the reinforcing layer, and the outer layer will be described below. As an extrusion molding method, for example, on the inner layer made of a fluororesin coated with an annealed copper wire, one is a strand made of a resin _{having a} melting point T _mfl (° C.), and the other is a resin having a melting point T _mfh (° C.) or higher. Alternatively, an intermediate tube is obtained by braiding a strand made of metal to form a braid. The whole or a portion of the intermediate tube covered with a heat shrinkable tube, is shrunk by heating at a temperature below T _mfl to a desired site (℃) or T _mfh (℃). Thereafter, the heat shrinkable tube is removed, and the resin constituting the outer layer is extruded onto the braid to form the outer layer. In this extrusion molding, it is more preferable to continuously give a hardness gradient in the longitudinal direction by switching extrusion. Next, a method for shrinking the outer layer resin using a heat shrinkable tube will be described. After the intermediate tube is constructed in the same manner as the above extrusion molding method, a hollow tube molded from a resin that forms an outer layer by extrusion is separately covered with the intermediate tube, and a heat shrinkable tube is further covered thereon. It is obtained by shrinking the covered tube in a heating furnace and then removing the heat shrinkable tube.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail according to an Example, this invention is not limited to a following example.

Example 1
Five cores of silver-plated annealed copper wire with a diameter of 0.52mm coated with polytetrafluoroethylene (PTFE) with a thickness of 0.030mm and five stainless steel wires (melting point 1400 ° C, diameter 0.030mm) on one side (left-handed) Wind in a side-by-side state, and on the other side (right-hand side), wind four polyethylene terephthalate fibers (melting point: 273 ° C, diameter 0.030mm) and five stainless steel wires side by side. A tube was prepared. Thereafter, a heat-shrinkable tube made of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) (inner diameter before shrinkage 0.81 mm, inner diameter after shrinkage 0.68 mm) was covered over the entire length of the intermediate tube. The entire length of the intermediate tube was heated with 290 ° C. hot air to shrink, and after cooling, the heat shrinkable tube was removed. Then, using polyamide elastomers (melting point 160 ° C-melting point 174 ° C) with Shore hardness 30D, 55D, 70D, each polyamide elastomer is supplied to three extruders connected before the crosshead die and melted. Mix and extrude into the intermediate tube. The temperature of the crosshead die is set to 210 ° C, the rotation speed of the gear pump attached to the tip of the extruder is continuously changed by computer control, the outer diameter and resin are changed, and the rigidity is continuously changed. A tube was prepared. The obtained tube had an outer diameter varying from 0.80 mm to 0.90 mm. A microcatheter was prepared by attaching a marker on the distal side and a hub on the proximal side, with the softest part being the distal side and the hardest part being the proximal side. In the obtained microcatheter, the polyethylene terephthalate fiber constituting the braided structure was melted and filled in the gaps between the stainless steel fine wires, and the irregularities derived from the braided structure were observed even at the smallest outer diameter of 0.80 mm. It showed a good appearance. The tip showed good flexibility, and there was no significant difference between the left and right in torque transmission, and operability such as kink resistance was also good.

(Example 2)
As a braided structure, five stainless steel wires (melting point 1400 ° C, diameter 0.030mm) are wound side by side on one side (left-handed), and polyethylene terephthalate fiber (melting point 273 ° C, diameter) on the other side (right-handed) An intermediate tube was obtained in the same manner as in Example 1 except that five 0.030 mm) were wound side by side. A heat-shrinkable tube made of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) (inner diameter before shrinkage: 0.81 mm, inner diameter after shrinkage: 0.68 mm) was covered in a range of 1000 mm from the tip of the intermediate tube. The range of 1000 mm from the tip of the intermediate tube was heated with hot air of 290 ° C. to shrink, and after cooling, the heat shrinkable tube was removed. Thereafter, a tube having an outer diameter of 0.75 mm to 0.90 mm was obtained in the same manner as in Example 1. A microcatheter was made by attaching a marker on the distal side and a hub on the proximal side. In the range of 1000 mm from the tip of the obtained microcatheter, the polyethylene terephthalate fiber constituting the braided structure was melted and filled in the gaps between the stainless steel fine wires, forming a pseudo-coil structure. At the boundary between the distal side heated with hot air and the proximal side not heated, the distal side heating changes the state of the polyethylene terephthalate fiber from a continuous unmelted and solidified state to an unmelted fiber state. Therefore, no local stiffness weakness was found. In addition, even with the smallest outer diameter of 0.75 mm, no irregularities were seen and a good appearance was shown. The tip showed particularly good flexibility, no significant left-right difference was observed in torque transmission, and operability such as kink resistance was also good.

(Example 3)
After producing an intermediate tube in the same manner as in Example 1, it was covered with a heat-shrinkable tube made of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and heated in a heating furnace at 180 ° C. for 5 minutes. After removing the heat-shrinkable tube, a microcatheter was produced in the same manner as in Example 1. The outer diameter of the obtained tube was 0.80 mm to 0.90 mm as in Example 1. As with the microcatheter of Example 1, the obtained microcatheter had good appearance and operability.

(Comparative Example 1)
As a braided structure, a microcatheter was obtained in the same manner as in Example 1 except that five stainless steel wires (0.030 mm in diameter) were wound side by side on both sides. The outer diameter of the obtained microcatheter was changed from 0.80 mm to 0.90 mm in the same manner as in Example 1. However, the portion with a small outer diameter had surface irregularities that seem to be derived from the braided structure, and the appearance was not good. Torque transmission and pushability were good, but the tip was hard and lacked flexibility.

1 is an overall view of a microcatheter of the present invention. It is the schematic which shows the braiding structure in the Example of this invention. It is the schematic which shows the braiding structure in the Example of this invention. It is the schematic which shows the braiding structure in the Example of this invention. It is the schematic which shows the braiding structure in the Example of this invention. It is the schematic which shows the braiding structure in the Example of this invention.

Explanation of symbols

1 Catheter body 2 Marker 3 Hub 11 _{Wire made} of resin with melting point T _mfl (° C) 12 _{Wire made} of resin or metal with melting point T _mfh (° C) or higher

Claims (5)

The reinforcing layer has a braided structure, and the braid is composed of strands of materials having different melting points, and at least one strand wound in one direction has a melting point T _mfl ( ° C), the remaining strand wound in the same direction as the strand made of the resin, and the strand wound only in the other direction intersecting the one spiral strand are melting point T _{It consists of} a resin or metal of _mfh (° C.) or higher, and the melting points T _mfl (° C.) and T _mfh (° C.) of the strands are _expressed using the melting point T _mo (° C.) of the resin constituting the outer layer:
T _mo +20 <T _mfl <350 and T _mfl <T _mfh
In a method for producing a microcatheter represented, by heating at a temperature below the portion of the microcatheter T _mfl (° C.) or higher T _mfh (° C.), wire made of a resin having a melting point T _mfl (° C.) A method for producing a microcatheter, comprising the step of melting at least a part of the outer layer, and then coating the outer layer. All of the strands wound in one direction that make up the braided structure have the formula:
T _mo +20 <T _mfl <350 and T _mfl <T _mfh
The method for producing a microcatheter according to claim 1, comprising a resin _having a melting point T _mfl (° C.) represented by: A portion of the distal microcatheter by heating in T _mfl below (℃) or T _mfh (℃) temperature, the step of melting at least a portion of the wire made of a resin melting point T _mfl (℃) The method for producing a microcatheter according to claim 1, wherein the outer layer is covered after that.   The method for manufacturing a microcatheter according to claim 3, wherein a part of the distal side of the microcatheter is in a range of 1000 mm from a tip of the microcatheter.   A microcatheter manufactured by the manufacturing method according to claim 1.