★★★★★
I've had SVT or Supraventricular Tachycardia for over 10 years now. It can be induced by stress, dehydration and who knows what else. Even a greasy meal once. I think depending on what triggers it different things will work for me. Rarely, a valsalva maneuver (which has about a 20-50% success rate, I think) will help.
Things that have I have switched between and tried (usually one about 20 minutes after the other with each unsuccessful attempt): magnesium oil sprayed on chest, powdered potassium supplement, big spoonful of blackstrap molasses. I don't try them in that order that's just a list of things that have worked for me.