A worthwhile addition if you're a Paramedic or other medically trained person.

https://www.alivecor.com/

I have one. For $99, it's quite the gadget. It records high quality Lead I ECG's. You can also do Lead II and one of the chest leads (V6?) with the device, but it appears quite inconvenient to do so. Lead I is a cinch however. Saves recordings locally (on your cellphone) for your review. Creates very nice PDF's from them. Allows you to email them wherever you want. You don't have to pay anything beyond the $99 device cost, but you can buy additional subscription services - like to store your recordings up int he cloud, have a clinician interpret them for you, etc. The gadget can only diagnose A-fib locally, but that's of no consequence if you're trained and able to diagnose an ECG on your own (that's what I do - I'm an expired Paramedic).

The device interfaces to your iPhone or Android phone/tablet via high frequency audio (uses the microphone on your cellphone). So you don't have to Bluetooth pair it. Just place the device within a foot of your cellphone. Note: Not every cellphone/tablet will be compatible with it. Depends on the microphone, etc. For example, I have an old iPhone 5S that works perfectly, but a new Kindle Fire HD8 tablet that does not. The manufacturer publishes a list of compatible devices, and you can always just try it with others to see if it works. If not, you can return it within 30 days.

I'm not affiliated with this company ... just happy with their product. It was recommended to me by one of my ER physician friends (who has one himself). And also by an Electrophysiology Cardiologist. The device is mostly marketed to the non-trained who would then send their recordings to their physician for interpretation. But I think it's even greater for Paramedics and such. Can't hardly go wrong for only $99. They have a more expensive iOS version that interfaces with other Apple gadgets (SmartWatch and such). But you can use the $99 model with iPhones, you don't need to get the fancy model.