Medical device

A medical device comprising:

• an expansion body configured to expand and contract in a radial direction;
• an elongated shaft including a distal portion that includes a proximal end fixing portion to which a proximal end of the expansion body is fixed;
• a plurality of electrode assemblies extending from the proximal end fixing portion of the shaft along at least a part of the expansion body;
• the expansion body includes a recessed portion that is recessed radially inward relative to portions of the expansion body proximal and distal of the recessed portion and that defines a receiving space to receive biological tissue when the expansion body is expanded while positioned in a hole in the biological tissue;
• the recessed portion of the expansion body including a radially innermost bottom portion including a proximal side curved portion and a distal side curved portion, a proximal side upright portion extending radially outward from the proximal side curved portion, and a distal side upright portion extending radially outward from the distal side curved portion, the proximal side curved portion being proximal of the distal side curved portion;
• each of the plurality of electrode assemblies including an electrode portion disposed along the expansion body from the proximal side upright portion to the bottom portion or from the distal side upright portion to the bottom portion, the electrode portion facing the receiving space;
• the proximal side curved portion and the distal side curved portion being deformable in response to expansion and contraction of the expansion body;
• the electrode portion is being in a floating state with respect to the distal side curved portion and the proximal side curved portion;
• the expansion body including a plurality of electrode engaging portions that each engage a respective one of the plurality of electrode assemblies;
• each of the plurality of electrode assemblies including an engaged portion that is engaged with a corresponding one of the electrode engaging portions;
• each of the electrode engaging portions is provided in at least one of the bottom portion, the proximal side upright portion, and the distal side upright portion of the recessed portion of the expansion body;
• the expansion body including a proximal side expansion portion extending radially outward from the proximal end fixing portion of the shaft toward a distal direction, and the proximal side expansion portion including an outward curved portion whose distal end is connected to a radially outer end of the proximal side upright portion, the outward curved portion being curved in a convex shape outward in the radial direction;
• the proximal side upright portion including a first through-hole passing through the expansion body;
• at least one of the plurality of electrode assemblies including an inner arrangement portion and an outer arrangement portion, the inner arrangement portion extending inside of the proximal side expansion portion from the distal portion of the shaft to the first through-hole, the outer arrangement portion extending along the expansion body from the first through-hole to at least the bottom portion of the recessed portion of the expansion body so as to face the receiving space;
• the outward curved portion of the proximal side expansion portion is configured to deform in response to the expansion and contraction of the expansion body,
• the inner arrangement portion is separated from the outward curved portion of the proximal side expansion portion at least when the expansion body is expanded;
• and
• the outer arrangement portion is in a floating state with respect to the distal side curved portion and the proximal side curved portion.