I had a similar concern when I was on a heavy Dbol cycle when I was younger.
I was experiencing seroius heart palpitations.
My girlfriend at the time was even able to feel the Kick in my chest.
Naturally I was very nervous. Went to the doctor and was told not to worry.
After some discussion I understood what was causing.
Basically he said the following to me.
"The symptoms of palpitations vary from patient to patient with some common features. A perception of irregularity of the pulse, an uneasiness in the chest, a flip-flopping in the chest; frequently people describe their palpitations as "my heart stops." Certainly a feeling of strong pulse throughout the chest, head and neck could well be described as a palpitation. Occasionally palpitations can be perceived in unusual ways including a general sense of uneasiness, and quite often the palpitations are associated with lightheadedness or even loss of consciousness".
My personal explination was the Flip Flop in the Chest.. Fealt like I skipped a beat and the following beat was really Strong. "Hense, the Thud in the chest"
NOTE:
The most common substance associated with palpitations is caffeine
So, if your on a strong ECA type stack then this may be the culprit..
So you know, the irregularity of the heart rhythm per se usually does no damage to the heart itself.
If you feel any pain in your chest when you expand your lungs or get a "Thump" beat. Don't worry...
The stress alone can bring on a heart attack.
Kro!