Patent ID: 8428703

Claim:
A cardiac monitor comprising: (a) a sensor adapted to sense an analog signal from a heart; (b) a device coupled to the sensor, the device having an analog-to-digital circuit system contained therein for digitizing the analog signal to produce a digitized waveform; (c) a processor electrically coupled to the analog-to-digital circuit system, said processor configured to: (i) compute a plurality of ST deviations from the digitized waveform, the plurality of ST deviations being characterized by a statistical distribution characterized by an upper boundary, a lower boundary, and a measure of dispersion; (ii) storing data pertaining to the plurality of ST deviations in a form that enables characteristics of the statistical distribution to be computed; (iii) form an upper detection threshold based on the upper boundary and the dispersion; (iv) compute a subsequent ST deviation from the digitized waveform; and (v) apply a test to detect a cardiac event, wherein the test is based on the subsequent ST deviation and the upper detection threshold; wherein the plurality of ST deviations are associated with a particular heart rate range; wherein the processor is further configured to store data pertaining to the plurality of ST deviations according to heart rate, thereby generating a corresponding plurality of values correlated with heart rate, and thereby generating set of statistical distributions, and for each member of the set, to form an upper detection threshold based on the upper boundary and the dispersion associated with the set; wherein both the plurality of ST deviations and the corresponding plurality of values correlated with heart rate each were generated at least in part with a corresponding one of two low pass filters; wherein each of the low pass filters is an exponential average filter.