Ablating apparatus

A medical apparatus for supporting and centering a treatment device treating the internal walls of a longitudinal cavity, in particular a human cavity, the apparatus comprising:

• a longitudinal sheath insertable in a working channel of an endoscopic device;
• and
• a positioning element comprising a first end connectable to the longitudinal sheath and having a central channel as well as a first guiding through-hole, a second end configured to be movable from the first end and from the longitudinal sheath and having a second guiding through-hole, and a deformable element fixable to at least the second end,
• wherein in a first configuration, or retracted configuration, the second end of the positioning element is at a first distance from the longitudinal sheath, the first guiding through-hole and the second guiding through-hole being aligned for receiving the treatment device and the deformable element is completely compressed in the direction of the longitudinal sheath, and
• wherein in a second configuration, or expanded configuration, the second end of the positioning element is spaced apart from the longitudinal sheath at a second distance, wherein the first distance is different from the second distance and the deformable element is radially expanded, thereby touching, at least partially, the internal walls of the cavity so that the first guiding through-hole and the second guiding through-hole are moved away from the internal walls of the cavity and the treatment device, when inserted into the first guiding through-hole and the second guiding through-hole, is moved towards a central region of the cavity and is maintained in said position during the treatment.