Electrogram signal filtering in systems for detecting ischemia

摘要

The present invention is a system that utilizes optimized high pass or band pass filtering to provide accurate detection of changes in the ST segment of an electrogram as detected by an implanted cardiosaver system, which ST segment changes are indicative of coronary ischemia. To accurately detect changes in the ST segment of the electrogram, the cardiosaver system uses either analog or digital high pass filtering having an electrogram voltage reduction of 6 dB at some frequency between 0.05 Hz and 1.0 Hz with less than 6 dB of attenuation at frequencies above 1.0 Hz. and more than 6 dB of attenuation for frequencies below 0.05 Hz. The optimized filter would include attenuation of electric power generation frequencies of either 50 Hz or 60 Hz to reduce electromagnetic interference. The system also includes both implanted and external portions that provide a patient alarm if coronary ischemia is sensed.