Submitted by Dr T on February 29, 2012 – 9:58am
You need to see your doctor and be tested under those conditions. I cannot judge whether you just feel your heart more because it drops a little closer to your chest wall when laying prone, or whether you have an abnormal heart rhythm. Your heart is protected within your chest cavity by your pericardium (heart sack), which normally has a little fluid in it that acts as a buffer when your body shifts position. This allows for some heart motion that also normally occurs when your heart is beating and contracting.
Hope this helps,