So we built probably cheapest ECG in the world, and it seems to work.
But does it really work?
Well, I wouldn't bet my life on it:)

So we made a call to association Big heart to small heart, a non-profit, humanitarian organization of doctors, health professionals and parents of children with congenital heart faults and other heart diseases, who happen to know 10000 children who might need such a device.

They connected us to doctor Hrvoje Kniewald, cardiologist at Department of Pediatric Cardiology in Zagreb, and made appointment.

To our surprise, we were greeted by six doctors!

Small room was full of people and we didn't even have opportunity to demontrate the device in action. But we did show them the device, and screenshots.

The conclusion was, YES, it works!

And, might be especially useful in one use case: arrhythmia that occurs rarely.

See, it's easy if you have heart condition and you know you have it. You get to your doc, he scans you and prescribes whatever necessary. But if your heart sometimes, just sometimes behaves, till you get there readings seem fine.

Doctors have put it very simple for us:
that's when healthy kid suddenly dies.

But, personal ECG allows to hook up fast, record the readings, and send the data to doctor by e-mail.

Err, what file format do you expect?

Don't bother with that, just send us the data, we'll deal with it.

Fine, we'll just record to CSV.

And we do. We also got few technical tips, like how to properly draw ECG, all implemented already.

Of course, there's some cons.

First, electrodes are impractical, especially one that needs to be tied to leg. If that takes too long, arrhythmia might pass.
Well, Olimex already sells different kind of electrodes, like, real ones. We did not purchase these for they are not open source:)

Second, the device requires PC to work. PC supplies it with electric power, but also with processing power, for it runs the software to display and save the data.
Well, we already demonstrated one way to build a portable DIY ECG, and this is clearly out of scope for this project.

Third, it's not very precise device. It does record PQRST - just enough for majority of people with heart conditions. But small beats outside of PQRST cannot be distingushed from noise.
This might be issue with our filters. So if anyone out there can do better, feel free to do it!

To conclude this log, I'll just say it's a good feeling knowing you maybe made a life saver.

You should try it yourself;)

But make no mistake, this is not a medical device! Certification procedures actually mean something, especially for medical devices: they mean you can bet your life on it.

Big thanks to Big heart to small heart and their good doctors.