I have constant high heart rate(Over 105) beats per min all the time Also many times I feel as if the heart stopped(hollow feeling) beating for 1-2 second before a Huge thump and it resumes normal rhythm This increases when I exercise or do any strenuous activity This started a few months ago when it happened frequently (1-2 times per minute and it was like this for a week or 2).. after that it reduced frequency to only a few times an hour. It feels like heart skipped a beat and then a thump I can feel prominently throughout and it goes back to normal