Filter
Top Products
6 ECG, Arrhythmia, and ST Monitoring About the ST Measurement Points
120
About the ST Measurement Points
The ST value for each beat complex is the vertical difference between the ISO point and the ST point,
as shown in the diagram below. The isoelectric (ISO) point provides the baseline, the ST point is at the
midpoint of the ST segment. The J point is where the QRS complex changes its slope; as it is a fixed
distance away from the ST point, it can be useful to help you position the ST point correctly.
CAUTION The ST measurement points need to be adjusted when you start monitoring, and if the patient's heart
rate or ECG morphology changes significantly, as this may affect the size of the QT interval and thus
the placement of the ST point. Artifactual ST segment depression or elevation may occur if the
isoelectric point or the ST point is incorrectly set.
Always ensure that ST measurement points are appropriate for your patient.
Adjusting ST Measurement Points
Depending on your monitor’s configuration, the ST point can be positioned either
• relative to the J-point.
In the Adjust ST Points window, the pop-up keys ISO Point, J Point and ST Point are
visible and can be adjusted.
or
• directly. by selecting a numeric value for the ST point.
In the Adjust ST Points window, you can adjust the ISO and ST point.
The ST Uses setting can only be changed in Configuration Mode.
To adjust the ST measurement points,
1 In the Setup ST Analysis menu, select Adjust ST Points to open the Adjust ST
Points
window. Alternatively, you can use the Adjust ST Points pop-up key in the ST
Baseline window.
2 Select a suitable ECG lead for ST measurement, with a visible J-point and a visible P wave. Use the
up and down arrow keys to scroll through the ST snippets for the other ECG leads.
J point, for example, 48 msec
R-wave peak at 0 msec
Isoelectric point set to -80 msec
Difference = ST value
ST measurement point, for example, J + 60 msec
T
P
Q
S