A medical implant device (18) for atrial appendage (20) is presented, suitable to transmit energy to its surrounding. The medical implant device (18) comprising an expandable structure(31,34) and a cover (32) disposed on the expandable structure is adapted toextend across the ostium (21) of the atrial appendage (20) for restricting migration of thrombi from the appendage to the blood stream in theheart (13). The expandable structure (31,34) of the medical implant device (18) configured to receive energy from an external energy source (11) is further configured to transmit energy to its surrounding for altering the electrical activation pathways in heart by heating the tissue adjacent to the medical implant device (18).