When examining the CCSHS edfs in Altamira I've noticed that many Heart Rates randomly freeze about halfway through the recording. What caused this? It's difficult to work with the data sometimes with limited documentation. Are there any additional resources we can turn to for explanations of the data generation etc? Thanks for your help.
See ccshs-trec-1800020.edf for one example. Notice how after the 50% marker or so the HRate freezes and never recovers.
Hi Chris, thanks for letting us know about this! Our team also opened this using another viewer to make sure it wasn't an Altamira-specific bug. A member of our team will look up the original source files to see if this issue was present prior to the export to EDF format.
I'm leaving a link here for future reference for our other team members to see the issue:
Sounds great thank you. If I can help in any way let me know. I have a list of all EDFs I found to have a frozen heart rate if that could aid the search in any way?
I asked some of our PSG experts here about this finding. The quick take is that the HRate channel is derived from within the scoring program, Compumedics Profusion, and is not often used. We don't have an immediate understanding about why the derivation breaks 50% of the way through this subset of CCSHS studies. We may explore further.
We will add a proper Montage and Sampling Rate Information page of documentation for CCSHS in the near future. We will note channels like HRate and others that are derived and were not part of the actual collection/scoring montage.
Any heart rate analyses should start by using the ECG channels that are present in the CCSHS EDFs.