Patent ID: 7844323

Claim:
A system for identifying an ischemic event in a human patient including: at least two electrodes implanted in the patient for obtaining an electrical signal from the patient's heart; an implanted device including: (a) analog-to-digital converter circuitry for digitizing the electrical signal to produce a multiplicity of segments, each having a duration of least 1 second, each of the periods between successive segments being at least as long as the segment duration; (b) memory means designed to store a first segment at a first predetermined time; (c) memory means designed to store a recently collected segment at a second time that is later than the first predetermined time; (d) processor means coupled to said memory means for comparing the ST segment voltage of at least one beat of the recently collected segment at the second time with the average ST segment voltage of at least two beats of the first segment stored in the memory means at the first predetermined time; and, (e) means for identifying that the ischemic event has occurred by applying a test that is based on whether the difference between the ST segment voltage of the at least one beat of the recently collected segment and the average ST segment voltage of the at least two beats of the first segment exceeds a detection threshold, wherein the detection threshold is a preset percentage of the average signal amplitude of the at least two beats of the first segment.