Systems and methods for adaptive filtering artifacts from composite signals

An element for filtering an artifact from an electrogram comprising

• means for inputting the electrogram,
• means for generating a variable correlated to the artifact,
• means for reducing the electrogram by the variable to derive a filtered electrogram signal,
• means for changing the variable over time based upon the energy of the filtered electrogram signal to minimize the energy of the artifact remaining in the filtered electrogram signal over time, and
• means for outputting the filtered electrogram signal.

A system for processing an electrogram comprising

• electrode means for electrically communicating with a heart,
• means coupled to the electrode means for pacing the heart while recording a paced electrogram IN(t) that changes with respect to time, the paced electrogram IN(t) comprising a useful electrogram portion that changes with respect to time EG(t) and that has an energy and a pacing artifact portion that changes with respect to time PACE(t) and that has an energy, and
• a processing element for removing the pacing artifact portion including
• filter means for generating an output TPACE(t) comprising a preselected function correlated to the pacing artifact portion,
• an input for receiving IN(t),
• means for subtracting TPACE(t) from IN(t) and generating the result as output EG(t), and
• the filter means being further operative for changing TPACE(t) over time based upon the energy of EG(t) so as to minimize the energy of the pacing artifact within EG(t) over time.