User Manual

ARRHYTHMIA ANALYSIS
PatientNet Operator’s Manual, v1.04, 10001001-00X, Draft 57
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Similar to the process used by clinicians to evaluate ECG, the algorithm determines if the
patient has previously had that type of beat, if it is occurring more frequently, or if the shape
(morphology) has changed. The technical name for this process is template matching.
Feature Extraction
Another aspect of arrhythmia analysis is feature extraction. Similar to template matching, fea-
ture extraction compares beats based on a series of characteristics. The algorithms measure a
set of features which may include the beat height, width, polarity, and interval. The beat’s fea-
ture set is then analyzed in relation to the feature set of other saved templates to determine if
the beat matches an existing template.
Step 6 - Multiple Beat Classification
Rhythm Analysis
After the beats are classified, the arrhythmia algorithm evaluates sequences of beats for vari-
ous sequence and/or rate related arrhythmias. As an example, if the algorithm detects alterna-
tive normal and ventricular beats for at least six beats, the algorithm calls Bigeminy.
Heart Rate Analysis
The arrhythmia heart rate is calculated as an 6-beat tracked average. All intervals are used for
heart rate calculations with the exception of the following:
1. Intervals of 3-seconds or greater
2. Intervals preceding or following unclassified beats (‘?’ beats)
3. Intervals that are more than +/- 25% different than the current average interval if the
longest consecutive bad sample (RF drop out) count is less than 16 samples (80 msec)
and the interval bad sample count is less than 37.5% of the interval sample count
The heart rate calculation is as follows:
New Heart Rate = Current Heart Rate – Current Heart Rate + Instantaneous Heart Rate
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