Dilator, introducer assembly, and medical tool

An introducer assembly comprising:

• a dilator which includes a first section, a second section, a third section, and a fourth section which have different diameters from each other and are formed to be adjacent to each other in an axial direction;
• and
• an introducer sheath which includes a lumen into which the dilator can be inserted and a distal portion,
• wherein the first section is adjacent to and disposed on a distal side of the second section, the second section is adjacent to and disposed on a distal side of the third section, and the third section is adjacent to and disposed on a distal side of the fourth section,
• an angle formed by an outer peripheral surface of the first section with respect to the axial direction is smaller than an angle formed by an outer peripheral surface of the second section with respect to the axial direction,
• the angle formed by the outer peripheral surface of the second section with respect to the axial direction is larger than an angle formed by an outer peripheral surface of the third section with respect to the axial direction,
• the angle formed by the outer peripheral surface of the third section with respect to the axial direction is smaller than an angle formed by an outer peripheral surface of the fourth section with respect to the axial direction, and
• a distal portion of the introducer sheath is disposed at a proximal end side with respect to a proximal end of the fourth section.

A medical tool comprising:

• a dilator which includes a first section, a second section, a third section, and a fourth section which have different diameters from each other and are formed to be adjacent to each other in an axial direction;
• and
• a needle which can form a hole communicating with a body lumen, by puncturing the skin,
• wherein the first section is adjacent to and disposed on a distal side of the second section, the second section is adjacent to and disposed on a distal side of the third section, and the third section is adjacent to and disposed on a distal side of the fourth section,
• an outer diameter of the first section is smaller than an outer diameter of the needle,
• an angle formed by an outer peripheral surface of the first section with respect to the axial direction is smaller than an angle formed by an outer peripheral surface of the second section with respect to the axial direction,
• the angle formed by the outer peripheral surface of the second section with respect to the axial direction is larger than an angle formed by an outer peripheral surface of the third section with respect to the axial direction, and
• the angle formed by the outer peripheral surface of the third section with respect to the axial direction is smaller than an angle formed by an outer peripheral surface of the fourth section with respect to the axial direction.