Patent Description:
For example, catheters for improving the blood flow by removing occlusions that block blood vessels, such as a chronic total occlusion (CTO), are known.

Among such catheters, there is known a catheter provided with a metal distal tip at a distal end for passing the catheter through a hard lesion site (see, for example, <CIT>).

<CIT> discloses a guidewire capable of penetrating a vascular occlusion, and provides a guidewire assembly wherein a stylet can be removably inserted into the length of the guidewire lumen to thereby enhance the guidewire structure.

In <CIT>, a catheter is configured to carry one or more stents and to have an inflatable balloon for expanding a stent surrounding the balloon.

<CIT> provides a catheter for distal removal of thrombi by suction, specifically designed for percutaneous coronary surgery operations, and which is easy and quick to manipulate and to position.

<CIT> describes a catheter capable of passing through a vascular occlusion.

<CIT> discloses a catheter for the dilation of stenotic lumenal occlusions, as well as methods of use for the device.

Further, <CIT> describes a catheter, which is capable of passing by or through a hard lesion, in accordance with the preamble of claim <NUM>.

It is required for catheters intended to be passed through a hard lesion that the catheter is easily passed through a lesion site and the damage to the catheter can be prevented when the catheter is passed through the lesion site.

An object of the present invention is to provide a catheter suitable for being easily passed through a hard lesion site and for preventing damage to blood vessels.

This object is solved by the subject-matter of the independent claim. Further aspects are disclosed in the subclaims.

According to the present invention, it is possible to provide a catheter suitable to be passed through a hard site.

Catheters according to several embodiments will be described with reference to the drawings (not all embodiments are covered by the subject-matter of the claims).

As used herein, the terms "distal end side" and "distal end direction" refer to a side and a direction where a distal tip is positioned with respect to a hollow shaft in a direction along a longitudinal direction of a catheter (direction along an axial direction of the hollow shaft). The terms "proximal end side" and "proximal end direction" refer to a side and a direction that are opposite to the distal end side and the distal end direction at a side and in a direction along a direction along the longitudinal direction of the catheter. Further, the term "distal end" refers to an end portion at the distal end side in any member or site, and the term "proximal end" refers to an end portion at the proximal end side in any member or site, respectively.

<FIG> is a diagram of a configuration of a catheter according to a first embodiment (not covered by the subject-matter of the claims). A catheter <NUM> includes a shaft <NUM>, a connector <NUM> provided on the proximal end side of the shaft <NUM>, and a distal tip <NUM> connected to the distal end side of the shaft <NUM>.

<FIG> illustrates a configuration of the vicinity of a distal end of the catheter illustrated in <FIG>, and more specifically, is an enlarged view of a cross section of a region R. The shaft <NUM> is a hollow member and includes a coil body <NUM>, an outer layer <NUM>, and an inner layer <NUM>.

The coil body <NUM> is an example of a reinforcing body that reinforces the shaft <NUM>, and is formed by spirally winding a metal wire. The coil body <NUM> may be formed by spirally winding one wire (solid wire coil), or may be formed by spirally winding a plurality of wires (stranded coil). Considering a rotation force of the catheter <NUM>, the coil body <NUM> is preferably a stranded coil. The metal material of the wire of the coil body <NUM> may be stainless steel (SUS304, SUS316, and the like), gold, platinum, tungsten, platinum, nickel, alloys containing these elements, and the like.

The outer layer <NUM> is a layer formed of a resin, for example, and is provided to cover an outer periphery of the coil body <NUM>. The resin material forming the outer layer <NUM> is not particularly limited, and may be, for example, a polyamide, a polyamide elastomer, a polyester, polyurethane, and the like.

The inner layer <NUM> is a layer formed of a resin, for example, and is provided to cover an inner periphery of the coil body <NUM>. The resin material forming the inner layer <NUM> is not particularly limited, but in consideration of slidability between the shaft <NUM> and an instrument (such as a guide wire) to be inserted inside the shaft <NUM>, PTFE (polytetrafluoroethylene) is preferable.

The distal tip <NUM> that is hollow and made of a metal, is connected to a distal end portion <NUM> of the shaft <NUM>. The distal tip <NUM> includes a main body portion <NUM> and a coating layer <NUM>.

The main body portion <NUM> is formed of a metal material. The metal material forming the main body portion <NUM> is not particularly limited, and may be stainless steel (SUS304, SUS316, and the like), gold, platinum, tungsten, platinum, nickel, alloys containing these elements, and the like. The distal tip <NUM> may be formed of a radiopaque metal material so that it is possible to grasp a position of a distal end of the catheter <NUM> in a radioscopic image.

The coating layer <NUM> is a layer formed of a resin, for example, and is provided to cover an outer periphery of the main body portion <NUM>. The resin material forming the coating layer <NUM> is not particularly limited, and may be, for example, a polyamide, a polyamide elastomer, a polyester, polyurethane, and the like.

The distal tip <NUM> includes, between the distal end of the distal tip <NUM> and the distal end portion <NUM> of the shaft <NUM>, an enlarged diameter portion <NUM> where an outer diameter in a direction perpendicular to the axial direction (longitudinal direction) of the shaft <NUM> is largest. An outer diameter DT1 of the enlarged diameter portion <NUM> is larger than an outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. An outer diameter of the main body portion <NUM> in the enlarged diameter portion <NUM> is also larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>.

The distal tip <NUM> is formed to have a tapered shape in which the outer diameter decreases from the enlarged diameter portion <NUM> toward the distal end, and the outer diameter decreases from the enlarged diameter portion <NUM> toward the distal end portion <NUM> of the shaft <NUM>. A rear end of the distal tip <NUM> has the same outer diameter as an outer diameter D2, and an outer peripheral edge of the rear end of the distal tip <NUM> is connected to an outer peripheral edge of the distal end portion <NUM> of the shaft <NUM>. The shaft <NUM> and the distal tip <NUM> are connected to have a continuous outer periphery.

The distal tip <NUM> and the shaft <NUM> are formed so that a rear end surface of the distal tip <NUM> and a distal end surface of the shaft <NUM> contact, at least in part, each other, and the rear end surface of the distal tip <NUM> and the distal end surface of the shaft <NUM> are joined to each other. As illustrated in <FIG>, the coil <NUM> and the main body portion <NUM> may be joined by welding at a surface where the metal materials contact each other. Moreover, the coating layer <NUM> and the outer layer <NUM> may be joined by thermal welding at a site where the resins contact each other.

If the catheter <NUM> is advanced through a hard lesion (for example, a calcified lesion), the shaft <NUM> passes through a portion through which the enlarged diameter portion <NUM> of the distal tip <NUM> passes. In the catheter <NUM>, the outer diameter of the distal end portion <NUM> of the shaft <NUM> is smaller than the outer diameter of the enlarged diameter portion <NUM>, so that a contact area between the lesion site and the shaft <NUM> is reduced. By reducing the contact area, it is possible to appropriately reduce the probability that the shaft <NUM> gets caught in the lesion or is damaged by the lesion. In addition, by reducing the contact area, it is possible to reduce the contact resistance by the shaft <NUM> when advancing the catheter <NUM>, and to improve the pushing force (pushability) of the catheter <NUM>.

<FIG> is a diagram of a configuration of the vicinity of a distal end of a catheter according to a second embodiment (not covered by the subject-matter of the claims), and illustrates a cross-section of the distal end of the catheter illustrated in <FIG>. A catheter 1A according to the second embodiment differs from the catheter <NUM> in the shape of the distal tip. Portions similar to those of the above-described embodiment are given the same reference symbols, and duplicated description is omitted. A distal tip <NUM> according to the second embodiment includes a main body portion <NUM> and a coating layer <NUM>. The main body portion <NUM> and the coating layer <NUM> are similar to the main body portion <NUM> and the coating layer <NUM>, except that the shapes are different.

The distal tip <NUM> includes, between the distal end and the distal end portion <NUM> of the shaft <NUM>, an enlarged diameter portion <NUM> where the outer diameter is largest. An outer diameter DT2 at the enlarged diameter portion <NUM> is larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. The outer diameter of the main body portion <NUM> at the enlarged diameter portion <NUM> is also larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. The distal tip <NUM> includes an outer peripheral surface <NUM> extending from the distal end side of the enlarged diameter portion <NUM> to the distal end portion <NUM> of the shaft <NUM> via the enlarged diameter portion <NUM>. As illustrated in <FIG>, the outer peripheral surface <NUM> is formed with an outwardly convex curved surface having an inclination gradually changing in a longitudinal sectional view of the catheter 1A, that is, a gently curved surface. The inclination refers to an amount of change of the outer peripheral surface <NUM> in a radial direction of the catheter 1A, with respect to the length in the axial direction of the catheter 1A, in a longitudinal sectional view.

According to the catheter 1A according to the present embodiment, in addition to the effects of the first embodiment (not covered by the subject-matter of the claims), when the catheter 1A is advanced toward the distal end side, it is possible to appropriately prevent damage to normal blood vessels that contact the enlarged diameter portion <NUM> of the distal tip <NUM> and the outer peripheral surface of the catheter 1A on the proximal end side of the enlarged diameter portion <NUM>.

<FIG> is a diagram of a configuration of the vicinity of a distal end of a catheter according to a third embodiment, which is an embodiment of the present invention, and illustrates a cross-section of the distal end of the catheter illustrated in <FIG>. A catheter 1B according to the third embodiment differs from the catheter <NUM> in the shape of the distal tip. Portions similar to those of the above-described embodiment are given the same reference symbols, and duplicated description is omitted. A distal tip <NUM> according to the third embodiment includes a main body portion <NUM> and a coating layer <NUM>. The main body portion <NUM> and the coating layer <NUM> are similar to the main body portion <NUM> and the coating layer <NUM>, except that the shapes are different.

The distal tip <NUM> includes, between the distal end and the distal end portion <NUM> of the shaft <NUM>, an enlarged diameter portion <NUM> where the outer diameter is largest. An outer diameter DT3 at the enlarged diameter portion <NUM> is larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. The outer diameter of the main body portion <NUM> at the enlarged diameter portion <NUM> is also larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. In the distal tip <NUM>, an outer peripheral surface <NUM> is formed with a more outwardly concave curved surface at the distal end portion <NUM> of the shaft <NUM> than at the enlarged diameter portion <NUM>.

If the catheter 1B is advanced through a hard lesion (for example, a calcified lesion), in a portion through which the enlarged diameter portion <NUM> of the distal tip <NUM> passes, it is possible to more effectively reduce the contact of the outer peripheral surface <NUM> at the proximal end side of the enlarged diameter portion <NUM> with the lesion. Thus, it is possible to appropriately reduce the probability that the outer peripheral surface <NUM> gets caught in the lesion. It is possible to reduce the probability that the enlarged diameter portion <NUM> of the distal tip <NUM> contacts the lesion, and thus, it is possible to reduce the contact resistance when advancing the catheter 1B, and to improve the pushing force (pushability) of the catheter 1B. If the catheter 1B is advanced toward the distal end side, the probability that the outer peripheral surface <NUM> of the distal tip <NUM> contacts a normal blood vessel can be reduced, and it is possible to appropriately prevent damage to blood vessels.

<FIG> is a diagram of a configuration of a distal tip of a catheter according to a fourth embodiment (not covered by the subject-matter of the claims), in which (A) is a cross-sectional view of the distal tip and (B) is a side view of the distal tip. In contrast to the distal tip <NUM> according to the first embodiment (not covered by the subject-matter of the claims), a distal tip <NUM> according to the fourth embodiment is formed with a slit <NUM>. The distal tip <NUM> includes a main body portion <NUM> and a coating layer <NUM>. The main body portion <NUM> is similar to the main body portion <NUM>, except that the main body portion <NUM> is formed with the slit <NUM>. The coating layer <NUM> is similar to the coating layer <NUM>, except that the coating layer <NUM> penetrates into the slit <NUM>.

In the main body portion <NUM>, as illustrated in <FIG>, the slit <NUM> is formed in a spiral shape. The slit <NUM> is provided to improve the flexibility of the main body portion <NUM> by cutting into the main body portion <NUM>. In the present embodiment, the slit <NUM> is formed in a spiral shape, and thus, the distal tip <NUM> can be bent equally easily in any direction. Since a pitch of the slit <NUM> is formed to decrease toward the distal end, a distal end region of the distal tip <NUM> is particularly flexible. Therefore, it is possible to reduce the risk of perforating a blood vessel with the distal tip <NUM>.

As illustrated in <FIG>, the distal tip <NUM> is configured such that the resin of the coating layer <NUM> penetrates inside the slit <NUM> of the main body portion <NUM>.

The distal tip <NUM> is provided with the slit <NUM>, so that the distal tip <NUM> can be easily bent while maintaining the hardness of the distal tip <NUM>. The outer peripheral surface of the distal tip <NUM> is covered with the coating layer <NUM>, and thus, it is possible to smooth the surface of the distal tip <NUM>. As a result, the catheter provided with the distal tip <NUM> can be easily passed through a hard lesion and exhibits good followability even in a tortuous blood vessel such as a peripheral blood vessel.

In the distal tip <NUM>, the resin of the coating layer <NUM> penetrates inside the slit <NUM>, so that it is possible to firmly fix the coating layer <NUM> to the main body portion <NUM>. Therefore, it is possible to appropriately prevent the coating layer <NUM> from detaching from the main body portion <NUM> due to friction with the outside. Thus, the smoothness of the outer peripheral surface of the distal tip <NUM> can be maintained, even if the distal tip <NUM> is passed through a hard lesion.

<FIG> is a diagram of a configuration of a distal tip of a catheter according to a fifth embodiment (not covered by the subject-matter of the claims), in which (A) is a side view of the distal tip and (B) is a side view of a distal tip according to a modification modified from the configuration illustrated in (A).

A distal tip <NUM> includes a main body portion <NUM>. The main body portion <NUM> is similar to the main body portion <NUM>, except that the shapes are different. The distal tip <NUM> includes, between the distal end and the distal end portion <NUM> of the shaft <NUM>, an enlarged diameter portion <NUM> where the outer diameter is largest. The enlarged diameter portion <NUM> has a predetermined width in the axial direction of the shaft <NUM>. The outer diameter at the enlarged diameter portion <NUM> is larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. A protruding portion <NUM> extending spirally and protruding radially outward of the main body portion <NUM> is provided on a surface (outer peripheral surface) of the main body portion <NUM> of the distal tip <NUM>. The protruding portion <NUM> is provided only within the range of the enlarged diameter portion <NUM>. According to the distal tip <NUM>, since the distal tip <NUM> is provided with the protruding portion <NUM>, it is possible to improve the penetrability into a hard lesion site.

The distal tip may be formed as a distal tip <NUM> illustrated in <FIG>. The distal tip <NUM> includes a main body portion <NUM>. The main body portion <NUM> is similar to the main body portion <NUM>, except that the shapes are different. The distal tip <NUM> includes, between the distal end and the distal end portion <NUM> of the shaft <NUM>, an enlarged diameter portion <NUM> where the outer diameter is largest. The enlarged diameter portion <NUM> has a predetermined width in the axial direction of the shaft <NUM>. The outer diameter at the enlarged diameter portion <NUM> is larger than the outer diameter DS of the distal end portion <NUM> of the shaft <NUM>. A protruding portion <NUM> extending spirally and protruding radially outward of the main body portion <NUM> is provided on a surface of the main body portion <NUM> of the distal tip <NUM>. The protruding portion <NUM> is provided in a range from the distal end side of the enlarged diameter portion <NUM> to a rear end of the enlarged diameter portion <NUM>. According to the distal tip <NUM>, since the protruding portion <NUM> is provided from the distal end side of the enlarged diameter portion <NUM>, it is possible to further improve the penetrability into a hard lesion site.

The technique disclosed herein may be modified into various modes without departing from the scope of the above-described embodiments and the modification. For example, the following modifications can be applied.

In the above-described embodiment, the shaft <NUM> includes the coil body <NUM> as an example of a reinforcing body of the shaft <NUM>. For example, a braid may be employed as the reinforcing body. If a braid is used as the reinforcing body, the braid and the distal tips <NUM>, <NUM>, and <NUM> may be joined by welding.

Claim 1:
A catheter (1B), comprising:
a hollow shaft (<NUM>); and
a distal tip (<NUM>) formed of metal and connected to a distal end portion (<NUM>) of the hollow shaft (<NUM>), wherein
the distal tip (<NUM>) includes, between a distal end of the distal tip (<NUM>) and the distal end portion (<NUM>) of the hollow shaft (<NUM>), an enlarged diameter portion (<NUM>) where an outer diameter (DT3) in a direction perpendicular to an axial direction of the hollow shaft (<NUM>) is largest;
characterized in that
the outer diameter (DT3) of the enlarged diameter portion (<NUM>) is larger than an outer diameter (DS) of the distal end portion (<NUM>) of the hollow shaft (<NUM>); and
the distal tip (<NUM>) is formed so that an outer shape (<NUM>) from the enlarged diameter portion (<NUM>) to the distal end portion (<NUM>) of the hollow shaft (<NUM>) is outwardly concave.