Heart catheter with means for measuring the contact

In a probe disposed at the distal end of a heart catheter for the coagulation of muscle and connective tissues by subjecting them to a high frequency field, a pressure sensor is provided for measuring the axial force effective on the probe tip which pressure sensor inlcudes a plastic body with an axial bore into which a light conductor extends and which has at its end opposite the light conductor a mirror for reflecting light supplied through the light conductor back into the light conductor. The plastic body is resiliently movably supported with respect to the light conductor so that the light reflected by the mirror back into the light conductor depends on the displacement of the probe tip caused by a pressure force applied to the probe tip.