Medical device and treatment method

A medical device for cutting substances inside a body lumen, the medical device comprising:

• a tubular drive shaft that is rotatable;
• a tubular outer sheath that can accommodate the drive shaft;
• at least one strut that is rotatably connected to a distal side of the drive shaft, that extends along a rotation axis, and whose central portion is bent to be expandable radially outward;
• a linear motion shaft that is arranged inside the drive shaft, and that expands the strut by moving relative to the drive shaft in an axial direction;
• and
• a liquid supply unit that supplies liquid to a portion between the outer sheath and the drive shaft and a portion between the drive shaft and the linear motion shaft, and wherein the liquid flows in a distal direction while the medical device is inserted into the body lumen.

A treatment method for cutting substances inside a body lumen by using a medical device including a tubular drive shaft that is rotatable, a tubular outer sheath that can accommodate the drive shaft, an inner tube arranged inside the tubular drive shaft having a lumen, at least one strut that is rotatably connected to a distal side of the drive shaft, that extends along a rotation axis, and whose central portion is bent to be expandable radially outward, a linear motion shaft that is arranged inside the drive shaft, and that expands the strut by moving relative to the drive shaft in an axial direction, and a liquid supply unit that supplies liquid to a portion between the outer sheath and the drive shaft, a portion between the drive shaft and the linear motion shaft, a portion between the inner tube and the tubular drive shaft, and the lumen of the inner tube, the treatment method comprising:

• inserting the at least one strut in a contracted state into the body lumen;
• expanding the at least one strut by moving the linear motion shaft relative to the drive shaft;
• cutting the substances inside the body lumen by causing the drive shaft to rotate the at least one strut;
• and
• supplying the liquid from the liquid supply unit to the portion between the outer sheath and the drive shaft, the portion between the drive shaft and the linear motion shaft, the portion between the inner tube and the tubular drive shaft, and the lumen of the inner tube so that the liquid flows in a distal direction while the medical device is inserted into the body lumen.