omg that totally happens to me, too. except i had a heart disease when i was a kid (multiple coronary anuerisms were involved) and i always thought it was related to that. but i was never diagnosed with anything else and i always wondered why i had still had weird pains every so often. interesting. that makes senses.
does your left tit bounce with your heartbeat? my left nipple piercing actually bounces slightly, along with my heartbeat... it's kinda funny...
(oh and - if you want a ring like the one on that website, i can totally make it for you for $40. i'm not doing the cast ones anymore though. just lemme know.)
Funny story, My mom, my sister and even my dad had been told they had heart murmurs and irregular heart beats by their family doctor. They went to a real cardiologist and found out that the doctor who originally diagnosed them doesn't know how to use a stethoscope.