Medical guidewire

There is provided a medical guidewire which reduces the resistance with a curved guiding catheter, and has improved durability that can keep the resistance reduced for a long time. A core shaft of the medical guidewire has a second cylindrical part, with a smaller diameter than that of a coiled body, on a proximal end side of the coiled body. This second cylindrical part is coated with a hydrophilic material. Further, the hydrophilic material coated on the second cylindrical part has a larger thickness than a hydrophilic material coated on the coiled body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Application No. 2010-010576 filed with the Japan Patent Office on Jan. 21, 2010, the entire content of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a medical guidewire.

BACKGROUND ART

There have conventionally been proposed a variety of medical guidewires for guiding a medical equipment such as a catheter which is used by being inserted into tubular organs such as blood vessels, digestive tracts and ureters, and intracorporeal tissues.

For example, a medical guidewire described in Patent Literature 1 (Japanese Patent Application Laid-Open No. 2008-307367) is made up of a wire body, a coil, a resin coating layer coated on this coil, and an annular member. The wire body has a certain diameter in a portion closer to the rear end than a tip portion, which is formed in tapered shape. The coil is a spiral coil that is wound around the tip portion of the wire body. The annular member is filled in a stepped space between a proximal end portion of the resin coating layer and the wire body.

Further, a hydrophilic lubricating layer is formed on the outer surface of the resin coating layer and the outer surface of the annular member in the medical guidewire described in Patent Literature 1.

It is described in Patent Literature 1 that in the case of using the medical guidewire and medical equipment in combination, the medical guidewire is prevented from getting caught in the medical equipment according to the invention described in this literature.

SUMMARY OF INVENTION

In the medical guidewire described in Patent Literature 1, the outer surface of the resin coating layer and the outer surface of the annular member are coated with the hydrophilic lubricating layer. However, there has been a problem with this medical guidewire in that in a curved area of a guiding catheter, the sliding resistance between the medical guidewire and the guiding catheter increases.

Further, during an operation by a physician, the medical guidewire and the guiding catheter continuously slide. It has thus been necessary to consider the durability of the medical guidewire which can keep the sliding resistance between the medical guidewire and the guiding catheter reduced as long as possible.

Moreover, in the medical guidewire described in Patent Literature 1, the annular member is filled in the stepped space between the proximal end portion of the resin coating layer and the wire body. However, a depressed portion with a corner is formed between the wire body and the annular member. There has thus been a problem in that the resistance generated at the time of manipulating the medical guidewire also increases due to this depressed portion.

Furthermore, since the depressed portion of the medical guidewire described in Patent Literature 1 has the corner, there has been a problem in that blood or bodily fluid may be accumulated in this depressed portion.

The present invention has been made in view of such circumstances. A first object of the present invention is to provide a medical guidewire reduced in resistance generated in the case of curving a guiding catheter. Further, a second object of the present invention is to provide a medical guidewire improved in durability that can keep the resistance reduced for a long time. Moreover, a third object of the present invention is to provide a medical guidewire which does not inhibit the flow of blood or bodily fluid at the time of manipulation.

A medical guidewire of the present invention is a medical guidewire including a core shaft and a coiled body that covers at least a tip portion of the core shaft, wherein especially the core shaft has a cylindrical part, with a smaller diameter than that of the coiled body, on a proximal end side of the coiled body, and the cylindrical part is coated with a hydrophilic material.

DESCRIPTION OF EMBODIMENTS

A first aspect of the invention is a medical guidewire including a core shaft and a coiled body that covers at least a tip portion of the core shaft, wherein especially the core shaft has a cylindrical part, with a smaller diameter than that of the coiled body, on a proximal end side of the coiled body, and the cylindrical part is coated with a hydrophilic material.

Further, a second aspect of the invention is the medical guidewire according to the first aspect, wherein the coiled body is also coated with the hydrophilic material, and a thickness of the hydrophilic material coated on the cylindrical part is larger than that of the hydrophilic material coated on the coiled body.

Further, a third aspect of the invention is the medical guidewire according to the second aspect, wherein a diameter of the cylindrical part including the hydrophilic material is smaller than that of the coiled body including the hydrophilic material.

Further, a fourth aspect of the invention is the medical guidewire according to any one of the first to third aspects, wherein an area from a proximal end portion of the coiled body to the cylindrical part is formed in streamlined shape.

Further, a fifth aspect of the invention is the medical guidewire according to the fourth aspect, wherein a middle area from the proximal end portion of the coiled body to the cylindrical part is formed in linear shape.

Further, a sixth aspect of the invention is the medical guidewire according to any one of the first to fifth aspects, wherein the cylindrical part is provided within a range of 50 to 350 mm from the tip of the core shaft.

According to the first aspect of the invention, the core shaft of the medical guidewire has the cylindrical part, with a smaller diameter than that of the coiled body, on the proximal end side of the coiled body. Further, the cylindrical part is coated with the hydrophilic material. It is thus possible to ensure a space between the guiding catheter and the cylindrical part of the medical guidewire inserted inside the guiding catheter. Moreover, this core shaft is provided with the cylindrical part having a certain diameter. Therefore, even in the case of the inner surface of the guiding catheter and the outer surface of the guidewire coming into contact with each other when the guiding catheter is curved, the manipulability of the guidewire remains unchanged. Furthermore, the cylindrical part is coated with the hydrophilic material. It is thus possible to further reduce the sliding resistance between the guiding catheter and the medical guidewire. Hence it is possible to provide a medical guidewire with favorable manipulability for a physician who performs an operation.

Further, according to the second aspect of the invention, the coiled body is also coated with the hydrophilic material, and the thickness of the hydrophilic material coated on the cylindrical part is larger than that of the hydrophilic material coated on the coiled body. Therefore, in addition to the effect of the first aspect, even in the case of the physician continuing the operation for a long period of time, it is possible to keep the resistance between the guiding catheter and the medical guidewire reduced. That is, the durability of the medical guidewire can be improved.

Further, according to the third aspect of the invention, the diameter of the cylindrical part including the hydrophilic material is smaller than that of the coiled body including the hydrophilic material. Therefore, in addition to the effect of the second aspect, it is possible to provide a medical guidewire with further favorable manipulability for the physician who performs the operation.

Further, according to the fourth aspect of the invention, the area from the proximal end portion of the coiled body to the cylindrical part is formed in streamlined shape. Therefore, in addition to the effect of the first aspect, the sliding resistance can be reduced in the case of pulling the medical guidewire inside the catheter, a tubular organ or an intracorporeal tissue. Hence it is possible to provide a medical guidewire with further favorable manipulability for the physician who performs the operation.

According to the fifth aspect of the invention, the middle area from the proximal end portion of the coiled body to the cylindrical part is formed in linear shape. Therefore, in addition to the effect of the fourth aspect, the blood or the bodily fluid is not accumulated, and the flow of the blood or the bodily fluid is not inhibited.

Further, according to the invention in accordance with the sixth aspect of the invention, the cylindrical part is provided within the range of 50 to 350 mm from the tip of the core shaft. It is thus possible to provide the medical guidewire particularly suitable for a curved shape that occurs in the case of applying the guiding catheter to the heart.

Hereinafter, the medical guidewire of the present invention will be described based on preferred embodiments illustrated in the drawings.

First Embodiment

FIG. 1illustrates an overall view of a medical guidewire according to a first embodiment of the present invention.

It is to be noted that inFIG. 1, a description is given with the left side defined as a “proximal end”, and the right side defined as a “tip” for convenience of description.

Further, inFIG. 1, the medical guidewire is reduced in length direction, and illustrated in an overall schematic manner for the sake of easy understanding. An overall size illustrated inFIG. 1is thus different from an actual size.

InFIG. 1, a medical guidewire1is made up of a core shaft3and a coiled body5that covers a tip portion of the core shaft3. The tip portion of the core shaft3and a tip portion of the coiled body5are fixed to each other at an extreme tip portion9.

A material for the core shaft3is not particularly limited. In the present embodiment, stainless steel (SUS304) is used as the material for the core shaft3. Other than that, a material such as a super elastic alloy like an Ni—Ti alloy, a piano wire, or a tungsten wire may be used.

As a whole, the core shaft3has a shape tapering down from the proximal end side toward the tip side. The core shaft3includes: a first cylindrical part21located in a position with a predetermined distance from the proximal end; a first taper part27adjacent to the tip side of the first cylindrical part21; a second cylindrical part11(corresponding to the cylindrical part of the present invention) adjacent to the tip side of the first taper part27; a second taper part25adjacent to the tip side of the second cylindrical part11; a third cylindrical part19adjacent to the tip side of the second taper part25; a third taper part29adjacent to the tip side of the third cylindrical part19; a fourth cylindrical part31adjacent to the tip side of the third taper part29; a taper press part33adjacent to the tip side of the fourth cylindrical part31; and a cylindrical press part35adjacent to the tip side of the taper press part33.

It is to be noted that the taper press part33is one with its side section formed in taper shape by pressing. The cylindrical press part35is one with its side section formed in cylindrical shape by pressing.

The second cylindrical part11is formed in a range of 50 to 350 mm from the tip of the medical guidewire1. Herein, the range of 50 to 350 mm is a range corresponding to an area where the medical guidewire1is curved by a relatively large amount when used along with a guiding catheter disposed in an area from a femoral artery to a heart.

Herein, an operation of using the medical guidewire1and the guiding catheter as medical equipment in combination will be described with reference to the drawings.

FIGS. 6 to 8each illustrate an explanatory drawing of the state of a guiding catheter51as medical equipment disposed in the area from the femoral artery to the heart, and the medical guidewire1.FIG. 6illustrates a state where the tip of the medical guidewire1has reached a left main trunk61of a left coronary artery67.FIG. 7illustrates a state where the tip of the medical guidewire1has reached a stenosis part71located in a left anterior descending artery63of the left coronary artery67.FIG. 8illustrates a state where the tip of the medical guidewire1has reached a distal part of the left anterior descending artery63.

In this operation, first, as illustrated inFIG. 6, a tip portion of the guiding catheter51is made to proceed from the femoral artery to a descending aorta57, an aortic arc55and an ascending aorta65. This tip portion is then fixedly placed in a right coronary artery59just before an aortic valve53or at one inlet of the left coronary artery67(inFIG. 6, the guiding catheter51is fixedly placed at the inlet of the left coronary artery67). The medical guidewire1is then inserted inside the fixedly placed guiding catheter51, and protruded from the tip portion of the guiding catheter51.

It is to be noted that the left coronary artery67is made up of the left main trunk61, a left circumflex artery69and the left anterior descending artery63. The left main trunk61is located upstream of the artery. The left circumflex artery69is located downstream of one branch in the left main trunk61. The left anterior descending artery63is located downstream of the other branch in the left main trunk61.

Herein, for example, in the case where the stenosis part71exists in a predetermined position of the left anterior descending artery63, as illustrated inFIG. 7, the medical guidewire1is made to proceed to the position of the stenosis part71. Thereby, the portion formed with the stenosis part71in the artery is treated.

Further, as illustrated inFIG. 8, the guidewire1can also be made to proceed to the distal part of the left anterior descending artery63.

As illustrated inFIGS. 6 to 8, the fixedly placed guiding catheter51extends almost linearly from the femoral artery, and is curved in a first area73from the descending aorta57to the aortic arc55. Moreover, the guiding catheter51is curved in a second area75from the ascending aorta65to the left coronary artery67, with a smaller radius of curvature, and is curved in a third area77in the vicinity of the inlet of the left coronary artery67, with an even smaller radius of curvature.

As described above, the second cylindrical part11is formed in the range of 50 to 350 mm from the tip of the medical guidewire1. This range corresponds to the third area77, the second area75, and the first area73.

In such a manner, in the medical guidewire1, the range of 50 to 350 mm from the tip is formed in cylindrical shape as the second cylindrical part11. This is for making uniform the sliding resistance between the guiding catheter51and the medical guidewire1in the third area77, the second area75and the first area73.

In contrast, when the second cylindrical part11is formed not in cylindrical shape but in, for example, tapered shape or conical shape, the sliding resistance may change in the third area77, the second area75or the first area73. Hence the manipulability of the medical guidewire1may decrease during an operation.

Further, the radii of curvature of the medical guidewire1in the second area75and the third area77are smaller than the radius of curvature in the first area73.

Hence, the effect can also be obtained even when the formation range of the second cylindrical part11is restricted only to a range corresponding to the second area75and the third area77. In that case, the second cylindrical part11may be formed in a range of 50 to 250 mm from the tip of the medical guidewire1.

It is to be noted that in the present embodiment, the second cylindrical part11of the medical guidewire1is formed based on the shape of the guiding catheter51disposed in the area from the femoral artery to the heart. However, a curved position varies depending on the site in the body where the guiding catheter51is used. Therefore, in the case of using the guiding catheter51in another site in the body, the second cylindrical part11of the medical guidewire1is preferably formed in accordance with a curved position of that site in the body.

Moreover, in the case of using the medical guidewire1and a medical equipment other than the guiding catheter in combination, the second cylindrical part11is preferably formed in accordance with a curved shape of the medical equipment.

However, in any case, common points are to form the second cylindrical part11in cylindrical shape, to form the second cylindrical part11on the side closer to the proximal end than the coiled body5, and to form the second cylindrical part11with a smaller outer diameter than that of the coiled body5.

Forming the second cylindrical part11on the proximal end side of the coiled body5, with the smaller outer diameter than that of the coiled body5, exerts the following effect.

That is, when the coiled body5including the extreme tip portion9of the medical guidewire1is inserted inside the body, the coiled body5passes through the inside of the body. Hence, in the body, a cavity corresponding to the outer diameter of the coiled body5is formed on the proximal end side of the coiled body5. The second cylindrical part11is formed, with a smaller outer diameter than that of the coiled body5, on the proximal end side of the coiled body5. For this reason, a space is generated between the second cylindrical part11and an inner wall of the cavity formed by passage of the coiled body5.

Generation of this space can reduce the sliding resistance between the second cylindrical part11and the inner wall of the cavity.

Further, as illustrated usingFIGS. 6 to 8, when the guiding catheter51is curved, or even when the medical guidewire1itself is solely curved in the body, it is possible to reduce the sliding resistance between the second cylindrical part11and the cavity formed by passage of the coiled body5.

A material for the coiled body5is not particularly limited. In the present embodiment, stainless steel (SUS304) is used as the material for the coiled body5. Other than that, similarly to the core shaft3, a material such as a super elastic alloy like an Ni—Ti alloy, a piano wire, or a tungsten wire may be used.

The coiled body5is wound in coiled shape around the tip portion of the core shaft3. The coiled body5is fixed by brazing to the tip portion of the core shaft3in a plurality of places, including a coil-tip brazed portion15continued to the extreme tip portion9, a plurality of coil-middle brazed portions that are located on the proximal end side of the coil-tip brazed portion15and include a coil-middle brazed portion17, and a coil-base-end brazed portion13located at the proximal end of the coiled body5.

It should be noted that inFIG. 1, only one coil-middle brazed portion17is illustrated, and the other coil-middle brazed portions are omitted.

In the vicinity of the extreme tip portion9, the coiled body5is wound so as to generate a space between adjacent wires of the coiled body5. On the other hand, on the proximal end side from the coil-middle brazed portion17that is adjacent to the proximal end side of the coil-tip brazed portion15, the coiled body5is wound such that adjacent wires of the coiled body5are in contact with each other.

It is to be noted that diameters of the wires of the coiled body5in the present embodiment are uniform. However, the diameters of the wires of the coiled body5may be decreased gradually from the proximal end toward the tip of the coiled body5. Further, the diameters of the wires of the coiled body5on the side closer to the tip than the coil-middle brazed portion17may be made smaller than those of the other wires of the coiled body5.

Decreasing the diameters of the wires of the coiled body5gradually from the proximal end toward the tip of the coiled body5can gradually enhance the flexibility of the tip portion of the medical guidewire1. This is effective in the case of curving the entire coiled body5.

Meanwhile, making smaller the diameters of the wires of the coiled body5, provided on the side closer to the tip than the coil-middle brazed portion17, than those of the other wires of the coiled body5can enhance the flexibility of a portion on the side closer to the tip than the coil-middle brazed portion17. This is effective in the case of curving the area on the side closer to the tip than the coil-middle brazed portion17, with a relatively small radius of curvature.

Further, the outer surfaces of the medical guidewire1from the extreme tip portion9to the coiled body5and the second cylindrical part11are coated with a hydrophilic material7.

It is to be noted that the hydrophilic material7in the present embodiment is hyaluronate.

The hydrophilic material7coated on the medical guidewire1reduces the sliding resistance of the medical guidewire1inside the catheter, the tubular organ or the intracorporeal tissue.

By coating the second cylindrical part11, with a smaller outer diameter than that of the coiled body5, with the hydrophilic material7in the present embodiment, it is possible to significantly reduce the sliding resistance between the guiding catheter and the medical guidewire1.

By applying the hydrophilic material7onto the outer surfaces of the medical guidewire1from the extreme tip portion9to the coiled body5and the second cylindrical part11such that the thickness is made uniform, it is possible to sufficiently reduce the sliding resistance.

It should be noted that the number of sliding of the medical guidewire1and the guiding catheter increases when a long period of time is required for the physician to perform the operation. In the present embodiment, consideration is also given in that respect.

FIG. 2illustrates a partially enlarged view of the second cylindrical part of the core shaft in the present embodiment.

InFIG. 2, the hydrophilic material7coated on the second cylindrical part11is formed with a larger thickness than that of the hydrophilic material7coated on the coiled body5.

That is, the hydrophilic material7is formed on the surface of the core shaft3such that a distance from the outer surface of the second cylindrical part11to the outer surface of the hydrophilic material7is longer than a distance from the outer surface of the coiled body5to the outer surface of the hydrophilic material7.

Further, the hydrophilic material7coated on the second cylindrical part11is formed with a larger thickness than those of the hydrophilic materials7coated on the first taper part27and the second taper part25which are adjacent to the second cylindrical part11.

Therefore, as illustrated inFIGS. 6 to 8, even when the medical guidewire1is slid for a long period of time with the guiding catheter curved, the sliding resistance in the second cylindrical part11does not increase.

Further, as illustrated inFIG. 2A, the diameter of the second cylindrical part11including the hydrophilic material7is desirably smaller than that of the coiled body5including the hydrophilic material7.

Making smaller the diameter of the second cylindrical part11including the hydrophilic material7than that of the coiled body5including the hydrophilic material7can generate a space between a cavity, formed by passage of the coiled body5through the inside of the guiding catheter, the tubular organ or the intracorporeal tissue, and the second cylindrical part located on the proximal end side of the coiled body5. Thereby, even when the medical guidewire1is slid for a long period of time with the guiding catheter curved, the sliding resistance between the guiding catheter and the medical guidewire1can be kept low.

Meanwhile, it is also preferable to reduce the sliding resistance of the medical guidewire1not only in the case of pushing the medical guidewire1but also in the case of pulling the medical guidewire1. In the present invention, consideration is also given in that respect.

FIG. 3illustrates a partially enlarged view of the state of connection between the core shaft and the coiled body in the present embodiment.

As illustrated inFIG. 3, the hydrophilic material7is applied so as to form a streamlined shape in the area from the proximal end portion of the coiled body5to the second taper part25. It is thus possible to reduce the sliding resistance of the medical guidewire1at the time of pulling the medical guidewire1inside the guiding catheter, the tubular organ or the intracorporeal tissue.

In the present embodiment, the hydrophilic material7is applied so as to form the streamlined shape in the area from the proximal end portion of the coiled body5to the second taper part25. However, this hydrophilic material7may be applied so as to form the streamlined shape in the area from the proximal end portion of the coiled body5to the second cylindrical part11. It is thus possible to reduce a depressed portion of the second taper part25. It is further possible to reduce the sliding resistance of the medical guidewire1at the time of pulling the medical guidewire1inside the guiding catheter, the tubular organ or the intracorporeal tissue.

It is to be noted that also in this case, the hydrophilic material7applied onto the second cylindrical part11is preferably formed with a larger thickness than those of the hydrophilic materials7applied onto the coiled body5, the first taper part27and the second taper part25.

In that case, it is possible to more favorably inhibit the increase in sliding resistance in the second cylindrical part11in the case of sliding the medical guidewire1for a long period of time with the guiding catheter curved.

Second Embodiment

Next, a second embodiment of the medical guidewire of the present invention will be described.

FIG. 4illustrates a partially enlarged view of the state of connection between a core shaft and a coiled body in the second embodiment.

InFIG. 4, the coil-base-end brazed portion13is made of a brazing material in streamlined shape which is formed in the area from the proximal end portion of the coiled body5to the second taper part25. The hydrophilic material7is applied with a uniform thickness onto the range from the coiled body5to the coil-base-end brazed portion13and the second taper part25.

Also by means of this medical guidewire1of the second embodiment, it is possible to reduce the sliding resistance of the medical guidewire1at the time of pulling the medical guidewire1inside the guiding catheter, the tubular organ or the intracorporeal tissue.

In the second embodiment, in the area from the proximal end portion of the coiled body5to the second taper part25, the brazed portion13is formed by use of the brazing material so as to form the streamlined shape. However, the area from the proximal end portion of the coiled body5to the second cylindrical part11may be formed in the streamlined shape by use of this brazing material. It is thus possible, as in the first embodiment, to reduce the depressed portion of the second taper part25. It is further possible to reduce the sliding resistance of the medical guidewire1at the time of pulling the medical guidewire1inside the guiding catheter, the tubular organ or the intracorporeal tissue.

In this case, the hydrophilic material7is applied with a uniform thickness onto the area from the coiled body5to the coil-base-end brazed portion13and the second cylindrical part11.

It is to be noted that also in this case, the hydrophilic material7applied onto the second cylindrical part11may be formed with a larger thickness than those of the hydrophilic materials7applied onto the coiled body5, the first taper part27and the second taper part25.

In that case, it is possible to more favorably inhibit the increase in sliding resistance in the second cylindrical part11in the case of sliding the medical guidewire1for a long period of time with the guiding catheter curved.

Third Embodiment

Next, a third embodiment of the medical guidewire of the present invention will be described.

FIG. 5illustrates a partially enlarged view of the state of connection between a core shaft and a coiled body in the third embodiment.

In the third embodiment, as illustrated inFIG. 5, the hydrophilic material7is applied so as to form a cylindrical shape (or linear shape) in a middle area from the proximal end portion of the coiled body5to the second cylindrical part11. Further, the hydrophilic material7is applied so as to form a curved shape in a connecting section between this middle area and the proximal end portion of the coiled body5, and applied so as to form a curved shape in a connecting section between the middle area and the second cylindrical part. It is thus possible to further reduce the sliding resistance of the medical guidewire1at the time of pulling the medical guidewire1inside the guiding catheter, the tubular organ or the intracorporeal tissue.

In an exemplary embodiment, there is a medical guidewire wherein a proximal end of the coiled body is joined to the core shaft at a joined portion, a first end of the joined portion closer to the proximal end of the coiled body has a first curved shape, a second end of the joined portion father from the proximal end of the coiled body has a second curved shape curved in a direction opposite the first curved shape, and the joined portion includes, from the first end to the second end, a streamlined shape in a longitudinal cross section of the guidewire. In yet another alternate embodiment, there is a medical guidewire wherein the proximal end of the coiled body is joined to the core shaft at a joined portion, a first end of the joined portion closer to the proximal end of the coiled body has a first curved shape, a second end of the joined portion father from the proximal end of the coiled body has a second curved shape curved in a direction opposite the first curved shape, and the joined portion includes, from the first end to the second end, a streamlined shape in a longitudinal cross section of the guidewire.

While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the spirit and scope of the invention.

REFERENCE SIGNS LIST