Many of us here experience health anxiety. Mine is centered around my heart like yours. I actually feel every beat and notice every little 'hiccup' in my chest. Before, I never gave a second thought to this, but when I experienced my first panic attack I believed I was actually having a heart attack. I went and got checked out by my doctors and everything checked out fine.
In my experience, once I went through this, I became VERY aware of every little sensation in my body in areas concerning my heart. I notice my pulse throughout my body, I can feel my self 'rock' to the beat of my heart when I lay down, etc. But it is actually normal; I just did not give it a second thought when I did not worry about it. Quite often we become oversensitized to our sensations and interpret them catastrophically when it is actually a 'normal' sensation.
As scaredjo says, get checked out by your doctor and then confront this anxiety head on why these worrisome thoughts are bothering you by going to talk to a therapist. You will be amazed how much you can learn about this and the various ways to thrive with what you are going through. Please keep us posted!
hiya loads of people have these symptoms with anxiety, heart related things are my speciality!! have you been checked by a doctor?