A device for supply of heat to body tissue, comprising heating means and a first temperature transducer which is insertable in the body tissue, the heating means being connected with an energy supply unit governed by a control unit via a catheter for treatment which is insertable in a body cavity and said first temperature transducer being operatively connected to the control unit. The control unit is operatively connected with memory means for storage of data corresponding to the survival of cells as a function of cell temperature. An input/output means is operatively connected to control unit to enter data such as desired volume/weight of body tissue to which heat is to be supplied to such an extent that the cells of the tissue die, and the control unit being operatively connected to calculation means for determining volume and weight of such body tissue whose cells have died as a function of temperature and time in the tissue at a certain distance from heating means.
