podevels,Hello and welcome to HealingWell. I understand your concerns as all of us worry from time to time about our cardiac status but this type of anxiety appears to be fairly common!
If you believe thee is something going on with your heart I encourage you to see your Dr. for a medical screening exam. Even though your anxiety is trying to convince you that you are dying - I truly suspect you are not and anxiety has just reared it's ugly head again.
The symptoms that you are feeling are absolutely real. The mind is very powerful, and can cause so many physical symptoms that can easily convince us that there is something very wrong...there is hope however! If our minds/thinking can get us to this place of panic...they can also bring us back to a place of healing! 
Keep posting here with us. We understand how you are feeling, and are here to listen and support! I look forward to getting to know you better.
Kindly,
Kitt