1) The Charge records steps, distance, floors climbed, active minutes, calories, sleep, it doesn't do heart rate.
2) If you need this for medical reasons, not just for fitness, stick with medically certified devices. There's a reason they cost more, and it's not profit. (The company that created the first "wearable" EKG lost a small fortune, but there were so many failsafes that you'd have to be run over by a steamroller while wearing it for it to get a wrong reading.)