Medical device and treatment method

A treatment method of enlarging a through-hole of an atrial septum by using a medical device having an expansion body that is configured to expand and contract in a radial direction and includes a distal side expansion portion and a proximal side expansion portion, the method comprising:

• expanding the distal side expansion portion of the expansion body in a radial direction inside a left atrium;
• positioning a distal side holding portion of the distal side expansion portion to face a surface on a left atrium side of the atrial septum so as to dispose a movable portion of the expansion body in the through-hole of the atrial septum, the movable portion of the expansion body linking the distal side holding portion and a proximal side holding portion of the proximal side expansion portion and forming a recessed portion with the proximal side holding portion and the distal side holding portion;
• expanding the proximal side holding portion in the radial direction inside a right atrium so as to hold the atrial septum from both sides of the through-hole by the recessed portion;
• expanding the movable portion, the distal side expansion portion and the proximal side expansion portion in the radial direction with holding the atrial septum from both sides of the through-hole by the recessed portion so as to enlarge a diameter of the through-hole by expanding the expansion body;
• and
• performing a maintenance treatment to the atrial septum held by the recessed portion by using a maintenance treatment element disposed on the recessed portion while the through-hole has been enlarged.

A medical device comprising:

• an elongated shaft portion;
• an expansion body disposed in a distal portion of the shaft portion, the expansion body including a plurality of wires in a circumferential direction, each of the plurality of wires configured to expand and contract in a radial direction;
• each of the plurality of wires comprising:
• a proximal side expansion portion extending radially in a distal direction from a proximal portion of the expansion body;
• a distal side expansion portion extending radially in a proximal direction from a distal portion of the expansion body;
• and
• a recessed portion disposed between the proximal side expansion portion and the distal side expansion portion and recessed radially inward;
• the recessed portion of each of the plurality of wires comprising:
• a proximal side erected portion connected to a distal end of the proximal side expansion portion;
• a bottom portion disposed innermost of the recessed portion and distal of the proximal side erected portion;
• and
• a distal side erected portion disposed distal of the bottom portion and connected to the distal side expansion portion;
• and
• wherein the expansion body is configured to expand to a first expanded state by a self-expanding force such that the bottom portion moves radially outward, and the proximal side erected portion and the distal side erected portion move closer to each other, and the expansion body is configured to expand a second expanded state further expanding than the first expanded state by the bottom portion, the proximal side expansion portion and distal side expansion portion moving radially outward.

A treatment method of enlarging a through-hole of a biological tissue by using a medical device having an expansion body having a plurality of wires in a circumferential direction, each of the plurality of wires configured to expand and contract in a radial direction, the method comprising:

• expanding a distal side expansion portion of the expansion body in the radial direction at a one side of the biological tissue and a proximal side expansion portion of the expansion body in the radial direction at an opposite side of the biological tissue opposed to the one side so as to position a recessed portion of each of the plurality of wires of the expansion body in the through-hole of the biological tissue and to receive the biological tissue in the recessed portion;
• enlarging a diameter of the through-hole with receiving the biological tissue in the recessed portion by the bottom portion of the recessed portion expanding radially outward into the biological tissue and the distal side expansion portion and the proximal side expansion portion expanding radially outward at both sides of the biological tissue;
• and
• performing a maintenance treatment to the biological tissue received in the recessed portion by using a maintenance treatment element disposed on the recess portion of the expansion body.