I read your question carefully and I understand your concern. Judging from that description I would say that a heart issue is very unlikely. One doesn t actually understand if heart has stopped beating, if it did there would be lack of blood flow to the brain which would cause lead to dizziness or fainting. I guess if one wanted to explore the issue to the end an EKG and perhaps a 24 hour Holter EKG (where you carry a device monitoring heart rhythm for 24 hours) may be done. However I believe the symptoms are most likely due to anxiety, which can often manifest this way, so nothing serious. I hope to have been of help.