The present invention concerns a catheter heating circuit for continuous cardiac
output measurement. The circuit comprises a DC power source for supplying an operating
voltage for the circuit, wherein the heating power from the heating circuit is
fed to the catheter via an isolating transformer. Isolation is known per se and
it is not described in detail. According to the invention the heating circuit further
comprises means for generating a bipolar square wave with variable duty cycle,
which square wave is supplied to said isolating transformer and further to the
catheter filament.
