Medical device

A medical device for cutting an object in a body lumen, the medical device comprising:

• a rotation structure having a cutting portion, the cutting portion including a notch on an outer surface of the cutting portion, the rotation structure including a distal tapered portion distal to a first non-cutting portion of the rotation structure, and a length of the notch is greater than a length of the distal tapered portion, and wherein the notch is between the first non-cutting portion of the rotation structure and a second non-cutting portion of the rotation structure, the first non-cutting portion of the rotation structure is a ring shape, and the second non-cutting portion of the rotation structure is in a proximal end of the rotation structure and a proximal end portion of the notch is continuous with the second non-cutting portion of the rotation;
• a first shaft configured to be connected to a center shaft of the rotation structure and configured to drive a rotation of the rotation structure;
• and
• a second shaft having a tubular shape, the second shaft configured to surround the first shaft and configured to be bendable at two positions including a first curved portion and a second curved portion, the second curved portion being located distally of the first curved portion.

A method for cutting substances inside a body lumen using a medical device, the medical device including a rotation structure having a cutting portion, the cutting portion including a notch on an outer surface of the cutting portion, the rotation structure including a distal tapered portion distal to a first non-cutting portion of the rotation structure, and a length of the notch is greater than a length of the distal tapered portion, and wherein the notch is between the first non-cutting portion of the rotation structure and a second non-cutting portion of the rotation structure, the first non-cutting portion of the rotation structure is a ring shape, and the second non-cutting portion of the rotation structure is in a proximal end of the rotation structure and a proximal end portion of the notch is continuous with the second non-cutting portion of the rotation, a first shaft configured to be connected to a center shaft of the rotation structure and configured to drive a rotation of the rotation structure, and a second shaft having a tubular shape, the second shaft configured to surround the first shaft and configured to be bendable at two positions including a first curved portion and a second curved portion, the second curved portion being located distally of the first curved portion, the method comprising:

• inserting the medical device into the body lumen;
• rotating the second shaft in a state in which a proximal side of the first curved portion and a distal side of the second curved portion of the second shaft are kept substantially parallel to each other;
• and
• cutting the substances inside the body lumen with the rotation structure that is on a distal end of the medical device while rotating the second shaft and keeping the rotation structure substantially parallel to the proximal side of the first curved portion and to the distal side of the second curved portion of the second shaft.