Sometimes my heart beats really fast and I can feel it thumping in my chest.  It feels like my heart is pushing through the chest walls.  This normally happens about twice a day and usually occurs when I am sitting.  It lasts about 15 minutes and then goes back to my normal rate.  Can you tell me the cause of this?
Hello! Welcome and thank you for asking on Chat Doctor! Your symptoms could be related to anxiety. But, before coming to this conclusion, I would recommend consulting with your attending physician for a careful physical exam and some tests to exclude some other possible causes