Checking the ECG Signal Strength
Evaluate the ECG signal produced by the patient before entry into the MRI scanner, the
optimum time to correct any problem.
A minimum signal strength should be present, as weaker signals may be prone to gradient
Selecting the Scale
The Scale setting only changes how the ECG trace appears on the screen—increasing or
decreasing the waveform and any artifacts. To increase the amplitude of the QRS complex, refer
to Changing the Lead View on page 5‐17.
To change the SCALE setting
5‐16 Monitoring ECG Expression MR400 Instructions for Use
Select Scale to adjust the displayed size of the waveform(s), where the scale indicator
provides, a 1 millivolt (mV) reference at any given setting; see Selecting the Scale, below).
Select Trace A Lead (or Trace B Lead) to adjust the configuration of the leads used for ECG
signal detection, where the best signal strength is indicated by the displayed peak‐to‐peak
amplitude of the QRS complex, which should be at least 1 mV (that is, the waveform
should be equal to the size of the scale indicator). In some cases, a 1 mV ECG signal cannot
be achieved due to patient physiology. In these cases, try to achieve the largest amplitude
attainable. See Changing the Lead View, on page 5‐17.
Ensure that the correct Patient Type has been selected; see page 3‐
11 for details.
Select the ECG VS box.
The ECG menu appears. Current settings are displayed.
The Scale menu appears; see page 5‐28.