The ECG Analysis Module is unable to detect the end of the T-wave if there is too much low-frequency noise (i.e. baseline drift) in the signal. Adding a High-Pass Filter of approximately 2Hz (varies by animal model) will remove low-frequency artifacts such as those caused by the breathing of the animal.
Add a Digital Filter by:
- Left-clicking the blue channel name label in the Chart View to access the Channel Function Pop-up Menu.
- Choose the Digital Filter option
- Select High-Pass as the Filter Type
- Enter the desired Cutoff Frequency
The reason this low-frequency noise affects the placement of the end of the T-wave is because the software looks for the point at which the waveform crosses back over the isoelectric line. Low-frequency noise can affect how the isoelectric line is calculated, which will in turn affect the point at which the waveform crosses over it. In some cases, the peak of the T-wave might appear to be below the isoelectric line, hindering marking of one or more T-wave components. Adding the High-Pass Filter will ensure that the isoelectric line will be in the correct place because there will not be drift due to the breathing of the animal, while keeping the actual ECG signal intact.
For further technical assistance with this or any other issue, please contact ADInstruments Technical Support by clicking HERE.