Finally have an answer re function of small 'ticks' below Kardia recording

[Buffafly]

I had a strange recording where a couple of HBs in a row would show as tiny hills rather than my usual small mountains. I noticed that the small markers under the hills were missing and wondered whether they referred to electrical signals or something else. I asked Kardia support who referred the question to the tech department. The markers count QRS complexes so my hills must have been too feeble to count!