Ok, I have sinus tach and pac's and pvc's, had them for years but just recently I feel this vibrating / shakiness in my chest all the time. I am on Atenolol to make my heart rate lower, and when I experience I do take my pulse and it's usually in the 70's or 80's.. I experience this vibrating / shaky feeling in my chest several times a day. I am 29 years old. Does anyone else ever experience this? I have been to my heart rhythm doctor and he can not explain what this is, nor anyone else... 