I grab an electrolyte drink and water and lay down on the floor or couch with my feet propped up. This allows your body to slow your heart rate and then the electrolyte drink helps keep it that way.

Agree. I found this out at my first ER visit (my first and most extreme episode). Hours after it started, i simply had brought my knees to my chest while still laying back on the ER bed. Immediately, my shaking subsided (just prior it was so bad before that i couldnt look up my notes on my phone, neither touching nor just reading). And my breathing and nausea started to settle too. I dont know about the heart rate; i didnt know to look yet. For me, i have used that ever since. I immediately sit down, slightly reclining is best for me, about 30 to 45 degrees. And then knees up, sometimes to my chest, but typically more like half that. Try it and see what works for you.