Hugo, cool teamwork with your cardiologist. We also do ECG with the OpenBCI hardware, so I'm totally onboard with the Maker approach. :-)
And... There are some really cool low cost tools for evaluating your HRV Heart Rate Variability. Which can show the balance of the Autonomic Nervous System / Sympathetic / Parasympathetic. Check out Marco Altini's apps, which work with iOS and a chest strap.
HRV as a metric of Heart Health, and biofeedback tool.
Hugo, thanks for the mention. Checkout our OpenBCI discussion forum,