Help with Arrythmia.?

I have a friend that has cardiac dysrhythmia. Whenever we climb up hills or if it�s too hot, then her heart rates gets faster. And she doesn�t do anything about it. She has seen doctors and specialists, but when it happens all she does is sit down and wait it out. Is there anything I can do to help? Maybe make it slow down a bit? I do check her heart rate, but that�s about all I�ve done. She doesn�t take any medicine so prescriptions wouldn�t help.