This will be long winded but basic. For 2 years now, I have been having the same symptoms. I feel absolutely fine, nothing abnormal on my day-to-day. But every now and then, I get a very sudden, and very brief (over within seconds) of lightheadedness. It starts in my head, I feel very lightheaded all of the sudden, like I am just about to pass out. I also get very hot. Then, I have an uncomfortable feeling in my chest, followed by weakness, shakiness, and I usually have to use the bathroom right after. After the initial episode, it takes me a few minutes to recoop. When I read about vasovagal responses, that is what it sounds like, but I don't know why they happen. I have found no common thread with the episodes meaning they happen sitting down, standing up, on no sleep, on a lot of sleep, hydrated or dehydrated, it doesn't matter what I do, they seem to be totally random. I have been to the ER, cardiologist, and neurologist. I have worn a heart monitor for a month, had several ECGs, a heart ultrasound, MRI, and bloodwork panels -- all of which come back normal/perfect. Outside of that, I feel perfectly normal. Every now and then it feels like my heart flutters for a second but thats it. ANY ideas? Any at all? Any sort of guidance will be greatly appreciated.