Perpetual motion machines are theoretical concepts of machines that can operate forever without any energy required from external sources. This is made possible by the fact that as the machine operates the output energy is more than the input energy. A part of the energy released is then used for the next cycle of operation but the net effect of the machine’s working is a production of energy. Once a perpetual motion machine has been started it can continue to operate indefinitely without further addition of energy.
If heat energy is added from an external source to a perpetual motion machine it would be released as an additional amount to the amount of energy that the machine anyway produces in the normal course of its operation.