B30 Patient Monitor
11-14
Description of the ST segment measurement algorithm
The ST segment begins at the point where the QRS ends (J point). Diagnostic criteria of ST
segment changes are measured at 60 ms after the J point. For monitoring purposes it is
important to keep the measurement point fixed during monitoring to notice the ST changes on
the respective trends.
The sophisticated algorithms of B30 monitors search the J and isoelectric (ISO) points. The
system learns the ECG and stores the reference QRST complex. The algorithm sets the ISO and
J points. Due to the large variation with QRST complexes the user has possibility to adjust the
ST measurement points manually. The QRS analysis classifies each beat by using several
criteria and rejects distorted complexes from the ST calculation.
NOTE: The ST algorithm has been tested for accuracy of the ST segment data. The significance
of the ST segment changes needs to be determined by a physician.
Test results of ST segment measurement algorithm testing
The algorithm testing has been performed by using The European Society of Cardiology ST-T
Database (ESC DB).
Average results from ischemic ST detection:
Episode sensitivity 84%
Episode positive predictive accuracy 70%
Duration sensitivity 64%
Duration positive predictive accuracy 74%
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