ST Segment Analysis ECG – Arrhythmia
9 - 30 V Series Operating Instructions
9.7.2.12 R-On-T PVC
The R-On-T PVC alarm is activated when the following occurs:
• A beat is detected as a PVC and previous beat is not a PVC and
• Current BTB heart rate is > 120 bpm and
• Current RR-interval is < previous RR-interval
The R-On-T PVC default alarm is a Medium level alarm event that produces:
• Medium level visual and audio alarm indicators.
•A R-On-T PVC text message above the primary waveform area.
9.8 ST Segment Analysis
WARNING: The ST algorithm has been tested for accuracy of the ST segment data.
The significance of the ST segment changes need to be determined by a
clinician.
The ST segment of an ECG waveform (as shown in FIGURE 9-23) 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
ST segments are typically calculated on graph paper with a scale of 1cm/mV, and measured in
millimeters where one millimeter is equivalent to 0.1 mV. The reliability of ST measurements is
lowered with the presence of atrial fibrillation, flutter, and erratic baseline changes.
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.
All available ECG leads are analyzed to measure deviations in the ST segment.
The displayed ST data is updated approximately every 10 seconds.
To Next Page
Loading...
Need help?
General
