Patent ID: 6128526
Filing Date: 2000-10-03
Classification: A61B,A61N

Abstract:
A method for use in a medical device which reads electrocardiogram signals and finds values associated with changes manifest in an ST segment of said electrocardiogram signal wherein said method filters an ST change parameter found in data extracted from measured samples of said ST segment at each cardiac cycle determined to be valid to determine whether a time course fluctuation of an ST change identified by said ST change parameter is representative of ischemia, said method comprising a repeated cycle comprising the steps:a) for a given cardiac cycle, collecting a selected set of characteristic portions of the electrocardiogram signal and sampling specific point locations within said portions,b) parameterizing each said sampled selected portion by calculating a plurality of characteristic parameter values based on measured values of said samples for each said portion collected in step a, wherein a plurality of point values are determined for an ST segment of said selected portion and a point value is determined for an isoelectric point of said selected portion,c) calculating a current ST change variable value for said given cardiac cycle using said plurality of point values and said isoelectric point value,d) determining if said current ST change variable value is within a previously determined expected range for said ST change variable wherein said previously determined expected range is based on previously calculated ST change variables and if said current ST change variable is within an expanded expected range beyond the previously determined expected range, said expected range is then updated based on said ST change variable, and said ST change variable is determined fit for use in determining ischemia and added to a series of ST change variables taken over previous cycles to produce an ST change parameter signal,e) determining whether said ST change parameter is changing in a manner indicative of a physiologic condition by a step of filtering the frequency of said ST change parameter using a bandpass filter and then producing from the output of said bandpas filter a raw physiologic indicator signal and then passing said raw physiologic indicator signal.