US-20260124434-A1 - GUIDEWIRE

US20260124434A1US 20260124434 A1US20260124434 A1US 20260124434A1US-20260124434-A1

Abstract

A guidewire includes a core wire, a resin sleeve, a front-end-side coil, a back-end-side coil, and an inside coil. The front-end-side coil includes a front end portion and a back end portion, each of which is fixed to a distal-end-side small-diameter portion of the core wire with solder. The back-end-side coil includes a solder-impregnated back end portion and a solder-unimpregnated front end portion. The solder-impregnated back end portion has an inner space impregnated with solder for fixing the back-end-side coil to the distal-end-side small-diameter portion of the core wire. The solder-unimpregnated front end portion has an inner space that is not impregnated with solder.

Inventors

Tsuyoshi Terashi
Hironori Kawasaki

Assignees

FMD CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20251031
Priority Date: 20241105

Claims (7)

1 . A guidewire comprising: a core wire; a resin sleeve disposed such that the resin sleeve is rotatable around a distal-end-side small-diameter portion of the core wire; a front-end-side coil formed of a compression coil spring having an outer diameter substantially equal to an outer diameter of the resin sleeve, the front-end-side coil being disposed on a front-end side of the resin sleeve so as to surround the distal-end-side small-diameter portion of the core wire and having a back end in contact with a front end surface of the resin sleeve; and a back-end-side coil formed of a compression coil spring having an outer diameter substantially equal to the outer diameter of the resin sleeve, the back-end-side coil being disposed on a back-end side of the resin sleeve so as to surround the distal-end-side small-diameter portion of the core wire and having a front end in contact with a back end surface of the resin sleeve, wherein the front-end-side coil includes a front end portion and a back end portion, each of which is fixed to the distal-end-side small-diameter portion of the core wire with solder, and wherein the back-end-side coil includes a solder-impregnated back end portion and a solder-unimpregnated front end portion, the solder-impregnated back end portion having an inner space impregnated with solder for fixing the back-end-side coil to the distal-end-side small-diameter portion of the core wire, the solder-unimpregnated front end portion having an inner space that is not impregnated with solder.
2 . The guidewire according to claim 1 , wherein the back-end-side coil has a coil outer diameter of 0.24 to 0.46 mm, the solder-unimpregnated front end portion has a length of 0.4 to 1.6 mm, and the solder-impregnated back end portion has a length of 0.4 to 1.6 mm.
3 . The guidewire according to claim 2 , wherein when the compression coil spring that forms the back-end-side coil includes a portion corresponding to the solder-unimpregnated front end portion and having a free length L o and a solid length L S the length L 41 of the solder-unimpregnated front end portion satisfies the following relationship: (L S + 0.05 mm) ≤ L 41 ≤ (L o - 0.1 mm).
4 . The guidewire according to claim 1 , comprising: an inside coil formed of a compression coil spring including a front end portion fixed to the distal-end-side small-diameter portion of the core wire together with the front end portion of the front-end-side coil, and a back end portion fixed to the distal-end-side small-diameter portion of the core wire with solder in an inner space of the resin sleeve.
5 . The guidewire according to claim 1 , wherein the resin sleeve includes a two-layer structure including an inner layer made of polyimide and an outer layer made of polyether block amide.
6 . The guidewire according to claim 1 , wherein the back end portion of the front-end-side coil includes a backmost end portion that is a solder-unimpregnated portion having an inner space that is not impregnated with solder.
7 . The guidewire according to claim 1 , wherein the back end of the front-end-side coil and the front end of the back-end-side coil are closed-ended.

Description

CROSS REFERENCES TO RELATED APPLICATIONS The present invention contains subject matter related to Japanese Patent Application No. 2024-193509 filed in the Japan Patent Office on November 5, 2024, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guidewire used to insert a medical apparatus into a living organism. 2. Description of the Related Art A guidewire including a resin sleeve disposed on a distal-end-side small-diameter portion of a core wire has been proposed as a medical guidewire with low resistance and high straight advancing capability (see Japanese Patent No. 4994381). The guidewire described in Japanese Patent No. 4994381 includes a core wire; a sleeve made of polyimide and disposed on a distal-end-side small-diameter portion of the core wire; and a front-end-side coil and a back-end-side coil disposed on the distal-end-side small-diameter portion of the core wire with the sleeve held therebetween. The sleeve of the guidewire is capable of rotating around the distal-end-side small-diameter portion of the core wire to facilitate torque transmission (paragraph 0024 of Japanese Patent No. 4994381). When a guidewire similar to that described in Japanese Patent No. 4994381 is manufactured, a back end portion of the sleeve may melt due to the heat of solder used in the process of fixing (soldering) the back-end-side coil to the distal-end-side small-diameter portion of the core wire. To avoid this, the back-end-side coil needs to be soldered at a position separated from a back end of the sleeve by a certain distance. Thus, in an actually manufactured guidewire, a front end of the back-end-side coil cannot be disposed in contact with a back end surface of the sleeve. As illustrated in FIG. 12, a gap G (step between the sleeve and the core wire and step between the back-end-side coil and the core wire) is inevitably formed between the sleeve and the back-end-side coil. When such a gap is formed, the guidewire may receive increased insertion resistance when inserted into a curved blood vessel or the like, and step portions of the gap may come into contact with a vascular plaque, which hinders the insertion of the guidewire. The gap (steps) also degrades the matching properties between the guidewire and a device, such as a catheter, used together with the guidewire. When the guidewire is bent, for example, by being inserted into a curved blood vessel, the sleeve tends to move slightly in a front-end direction relative to the core wire such that the back end surface of the sleeve moves in the same direction, thereby increasing the gap (distance between the back end surface of the sleeve and the front end of the back-end-side coil) after being bent. SUMMARY OF THE INVENTION The present invention has been made in light of the above-described circumstances, and its object is to provide a guidewire that has no gap between a sleeve and a back-end-side coil, that can be easily inserted into a curved blood vessel and has good matching properties with a device used therewith, and in which a back end portion of the resin sleeve does not melt due to the heat of soldering during manufacture thereof (soldering process of the back-end-side coil). (1) A guidewire according to the present invention includes a core wire, a resin sleeve, a front-end-side coil, and a back-end-side coil. The resin sleeve is disposed such that the resin sleeve is rotatable around a distal-end-side small-diameter portion of the core wire. The front-end-side coil is formed of a compression coil spring having an outer diameter substantially equal to an outer diameter of the resin sleeve. The front-end-side coil is disposed on a front-end side of the resin sleeve so as to surround the distal-end-side small-diameter portion of the core wire, and has a back end in contact with a front end surface of the resin sleeve. The back-end-side coil is formed of a compression coil spring having an outer diameter substantially equal to the outer diameter of the resin sleeve. The back-end-side coil is disposed on a back-end side of the resin sleeve so as to surround the distal-end-side small-diameter portion of the core wire, and has a front end in contact with a back end surface of the resin sleeve. The front-end-side coil includes a front end portion and a back end portion, each of which is fixed to the distal-end-side small-diameter portion of the core wire with solder. The back-end-side coil includes a solder-impregnated back end portion and a solder-unimpregnated front end portion. The solder-impregnated back end portion has an inner space impregnated with solder for fixing the back-end-side coil to the distal-end-side small-diameter portion of the core wire. The solder-unimpregnated front end portion has an inner space that is not impregnated with solder. According to the guidewire having the above-described structure, the back-end-side coil, which