BeneVision TM80, Operator'S Manual

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13 - 6 BeneVision TM80 Telemetry Monitor Operator’s Manual
NOTE
•
The display of the QT digital area differs as related settings change.
13.6 ST Monitoring
A normal ECG waveform (for ST monitoring)
The ST segment of an ECG waveform (as shown in the above figure) represents the period
from the end of ventricular de-polarization, to the beginning of ventricular re-polarization,
or the end of the QRS complex (the J point) and the beginning of the T-wave. ST Segment
analysis is used to monitor the oxygen supply and the viability of the heart muscle.
ST deviation is the vertical distance between the isoelectric (ISO) point level and signal
level at ST point.
The ISO point is located between the end of the P-wave and the onset of the QRS complex.
The ISO point provides the baseline for this measurement.
The ST point is a fixed distance from the J point at the end of the QRS complex. The ST point
can be configured to 40, 60, or 80 milliseconds past the J-point, independent of the heart
rate. By default, the ST point is positioned as follows:
■
at 80 milliseconds for heart rates less than or equal to 120 beats per minute
■ at 60 milliseconds for heart rates greater than 120 beats per minute
All available ECG leads are analyzed to measure deviations in the ST segment.
Selecting leads that contain the least amount of baseline flutter will improve measurement
accuracy, but accurate ST deviation measurement is dependent on the correct location of
the ISO and ST points.
R
P
T
S
ST P
o
int
J P
o
int
ISO
P
o
int
40 to 80 msec
ST deviation
Depression or Elevation
ST Segment