Steps for an inverted QRS wave:
Open AcqKnowledge
Select “analyze only” and then click “ok” on the pop-up menu
Change the file type to txt file, select your ECG file, and then click “open”
Enter your sampling rate in milliseconds/sample for the sampling rate interval (250 Hz will be 4 ms/s) and click “ok”
Go to “transform” → “expression” and then enter “-CH0” into the box and click “ok”
Minimize CH0 by clicking on the drop-down arrow in the left hand corner of the channel
Click on CH1, resize the channel by entering ctrl+y.
Relabel the left side of the channel with “ECG” and the right hand side with “mV”
To filter the data, go to “transform” → “digital filters” → “comb band stop” and click “ok”
Steps for a normal QRS wave:
Open AcqKnowledge
Select “analyze only” and then click “ok” on the pop-up menu
Change the file type to txt file, select your ECG file, and then click “open”
Enter your sampling rate in milliseconds/sample for the sampling rate interval (250 Hz will be 4 ms/s) and click “ok”
Relabel the left side of the channel with “ECG” and the right hand side with “mV”
To filter the data, go to “transform” → “digital filters” → “comb band stop” and click “ok”
After filtering:
Resize the dataset by going to “auto scale” and then entering ctrl+y
Scan for artifacts
Zoom in on artifacts using the zoom tool
To correct a missed QRS peak, take the I-beam tool and highlight from one end of the peak to the next.
Go to “transform” → “waveform math”
Make sure that
Source 1 = the channel you are on
Addition is selected
Source 2 = K, a constant
Destination = the channel you are on
Enter a constant to add to the waveform and click “ok”
To correct noise that could interfere with QRS detection, highlight from the end of one QRS peak to the start of the next QRS peak using the I-beam tool.
Go to “transform” → “math functions” → “connect endpoints”
Repeat this process for any artifacts. Be sure to scan the entire waveform for artifacts before exporting.
Remove any extraneous channels (otherwise these will be exported with the corrected channel) by selecting the channel you want to remove, and going to “edit” → “remove waveform”.
Then, once you are ready to export go to “file” → “save as” and select txt file from the file type menu. Name your file, then click “save” and then “ok”
