A method and apparatus for remotely monitoring the location of an interventional medical device (IMD) which monitors changes in frequency response characteristics of a sensor. Embodiments of the present invention may use changes in the complex impedance properties of the sensor, at antiresonance, or changes in the resonant frequency of an LC circuit to indicate whether or not the IMD is in contact with a tissue surface. The present invention is adapted for use in conjunction with a wide variety of IMDs, and in a wide variety of medical procedures.