Just got back from ER after an episode last night of rapid heart beat for 3 hours when I bend down and dizziness. All tests EKG and blood work is normal I have had this problem for years but episodes have increased over the last few years. I have AFIB and have been on medication for 15 years, also for high BP, which is now in the normal range. After reading all the posts of people who suffer from this syndrome, I feel better. Dehydration and fatigue seem to be a factor, so I will check my thyroid and try to drink more water and not overdo anything. I am 82 years old and doc says I am depressed because my husband of 60 years died last year and wants me to take antidepressants. I am sad but not depressed and I refused the meds. It would be better for me if I did not experience the rapid heart beat and lightheadedness when I bend over (only sometimes, not always) Thanks for the information.