Paul pretended :
The screen output on mine looks like this. And I do
like the waveform feature, because you can see
a correspondence between the waveform, and when
you have a "fluttery feeling" in the chest.

Mine shows a tiny crude cardio, but I don't know whether it is a
genuine cardio or synthesised. In interviews with the docs, they have
asked me if I ever notice heart palpitations - not really knowing what
one should feel like, all I can reply is that I have absolutely no
idea.

The only times I notice my heartbeat is when I feel my wrist or temple
etc. for it, or sometimes can audibly hear the beat in my ears. I
asked, and was told that is quite normal.