I have the same feeling. After years of cardio visits, i have recently found out the problem. I have a small tear in my atrial septrum, also called a "murmur" you should get it checked out by a cardiologist, you never know...
You are not alone. Have had the very same thing happeen to me. I hate it because it makes you feel like your heart is just going to stop. I have felt the vibrations too. I wish I had an answer for you, then I would have one for me too. Anybody else out there have any ideas??????
Fritzie92