IP Library › Granted Patent US 12,691,254
Granted Patent B2
US 12,691,254 · App. 18/214,005 · Granted Jul 28, 2026

Stylet and catheter assembly

Inventor: Masakazu Miyata (Fujinomiya, JP)
Assignee: Terumo Kabushiki Kaisha
A61M25/0102A61M25/0028A61M25/0043A61M2025/0063
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Quick Facts
Patent No.
US 12,691,254
App. No.
18/214,005
Granted
Jul 28, 2026
Kind
B2
Abstract

A stylet for axially stretching a catheter ensures flexibility in the distal side and a desired degree of stiffness in the proximal side to enable preferable insertion of a catheter assembly along a guidewire while preventing a kink or breakage. The stylet 50 includes a hollow outer layer tube 51 extending in an axial direction and a hollow inner layer tube 52 disposed in the inner periphery of the outer layer tube. The inner layer tube is formed from a material stiffer than that of the outer layer tube. In the inner layer tube, a distal portion has the inner periphery provided with a tapered diameter portion 52 B having a diameter reduced toward the proximal side in the axial direction.

Claims (30)

1 . A stylet configured to be insertable into a catheter including a lumen that allows passage of blood, the stylet comprising:

a hollow outer layer tube extending in an axial direction between a distal end and a proximal end and having an inner periphery; and

a hollow inner layer tube disposed in the inner periphery of the outer layer tube along an axial portion of the outer layer tube at the proximal end, and formed from a material stiffer than a material of the outer layer tube;

the inner layer tube including a distal portion having a reduced thickness wherein an inner periphery of the inner layer tube is provided with a tapered diameter portion having an inner diameter which is gradually reduced from a distal tip toward a proximal side of the inner layer tube in the axial direction.

2 . The stylet according to claim 1 wherein the inner periphery of the outer layer tube has a recess that is recessed radially outward within the axial portion of the outer layer tube at the proximal end; and

wherein the inner layer tube is fixed to the outer layer tube within the recess with the distal portion of the inner layer tube abutting against a distal portion of the recess of the outer layer tube.

3 . The stylet according to claim 1 wherein the tapered diameter portion has a linear shape.

4 . The stylet according to claim 1 wherein the tapered diameter portion has a curved shape protruding toward the proximal side.

5 . A catheter assembly comprising:

a catheter including a lumen that allows passage of blood; and

a stylet insertable into the lumen comprising:

a hollow outer layer tube extending in an axial direction between a distal end and a proximal end and having an inner periphery; and

a hollow inner layer tube disposed in the inner periphery of the outer layer tube along an axial portion of the outer layer tube at the proximal end, and formed from a material stiffer than a material of the outer layer tube;

the inner layer tube including a distal portion having a reduced thickness wherein an inner periphery of the inner layer tube is provided with a tapered diameter portion having an inner diameter which is gradually reduced from a distal tip toward a proximal side of the inner layer tube in the axial direction.

6 . The catheter assembly according to claim 5 :

wherein the inner periphery of the outer layer tube has a recess that is recessed radially outward within the axial portion of the outer layer tube at the proximal end; and

wherein the inner layer tube is fixed to the outer layer tube within the recess with a distal end of the inner layer tube abutting against a distal portion of the recess of the outer layer tube;

whereby the inner layer tube has the distal end disposed closer to the proximal end of the outer layer tube than the distal end of the outer layer tube.

7 . The catheter assembly according to claim 5 wherein the tapered diameter portion has a linear shape.

8 . The catheter assembly according to claim 5 wherein the tapered diameter portion has a curved shape protruding toward the proximal side.

9 . A catheter assembly comprising:

a catheter including a lumen that allows passage of blood; and

a stylet insertable into the lumen for stretching the catheter, comprising:

a hollow outer layer tube extending in an axial direction between a distal end and a proximal end and having an inner periphery, wherein the outer layer tube has a recess that is recessed radially outward within an axial portion of the outer layer tube at the proximal end; and

a hollow inner layer tube disposed in the recess;

wherein the inner layer tube is formed from a material which is stiffer than a material of which the outer layer tube is formed;

whereby the stylet has a distal end which is relatively flexible compared to a proximal end of the stylet.

10 . The catheter assembly according to claim 9 wherein the inner layer tube includes a distal portion having a reduced thickness wherein an inner periphery of the inner layer tube is provided with a tapered diameter portion having an inner diameter which is gradually reduced from a distal tip toward a proximal side of the inner layer tube in the axial direction.

11 . The catheter assembly according to claim 10 wherein the tapered diameter portion has a linear shape.

12 . The catheter assembly according to claim 10 wherein the tapered diameter portion has a curved shape protruding toward the proximal side.