Welch Allyn Holter System - User Manual - Manual (Page 47)

Directions for Use 43
ST Episodes are determined by summing the average ST level over a period of time.
Once the average ST Level exceeds the clinician selectable threshold, a ST Episode will
be started. The end point of the ST Episode is determined when the average level falls
below the clinician selectable threshold. A valid ST episode is reported when the length of
the ST episode exceeds the clinician selectable threshold. If a second ST episode starts
within the ST Reset threshold, the second ST episode is considered as part of the
previous episode.
The clinician has separate ST Elevation and ST Depression thresholds. During each ST
episode, the location of the maximum average values is maintained. The analysis program
does not identify ST slope levels. The clinician can review the ST strip examples to
determine if the ST segment slope is up, down or flat.
ST episodes are determined for each channel and for Elevation and Depression. These ST
episodes are sorted based on maximum level of depression or elevation and automatically
presented as strips within the report. The strip time reflects the time of maximum
depression or elevation. The duration of the ST episodes, ranges of displacement, or heart
rates are not reported.
Pattern Determination
The analysis program detects the following ventricular pattern types. N represents any
normal beat including S beats.
Table 8. Ventricular events patterns
Supraventricular detection is based on normal beats only. The normal beat must be
premature to the previous normal beat or to the running NN average rate. The prematurity
threshold is configurable. The analysis program detects the following supraventricular
pattern types:
Table 9. Supraventricular events patterns
The analysis program detects the following Rate related patterns:
Ventricular Event Type Pattern
Isolated N-V-N
Couplets N-V-V-N
Runs (three or more Ventriculars) N-V-V-V-N
Bigeminy N-V-N-V-N-V-N
Supraventricular Event Type Pattern
Isolated N-S-N
Couplets N-S-S-N
Runs (three or more Supraventriculars) N-S-S-S-N