This is normal for people with Anxiety/Panic issues. the ekg and the ultrasound mean allot concerning your heart. your question is like asking how can a x-ray tell if I have a broken bone.
It's good that you are getting test to R/O anything phisically medical. but I am sure you will find both test fine. So after that happens I would suggest you really start accepting your Anxiety issues and work on the cause. as for your last statement, I remind people that unless they are Medical Doctors , please do not try to self dx yourself," had an irregular heartbeat a couple skips about 10 minutes after my workout". Understand you worked out and your heart rate will go up and down through out the day, but understand you are so aware of it, that you, like many others seem to dwell on this not realizing that this is NORMAL. I wish you the best of luck and keep posting on your progress.
For the skipped heart beats you might want to try a BATA blocker. Ask your doctor. That took them away for me. For dissiness get a blood test to make sure your red blood cells are working properly getting all the oxygen to your mussels and brain as needed.
bbq33
We've been down this road, and it genuinely seems as though you just cannot accept the reassurance that the docs have given you. If there was something seriously wrong with your heart, your work-ups would have found it. There are all kinds of benign heart conditions, like heart murmurs (one, MVP or mitral valave prolapse) that carry a strong correlation between it and anxiety disorders.
One last time...to try to finally put this behind you and believe the results...see a cardiologist. At the same time you make that appt, make one with a psychiatrist, so that as soon as you get an "a-ok" from the cardiologist...you can finally start dealing with the real issue here, anxiety. If you have one of these benign conditions, the heart doc will find it and recommend any treatment to control your symptoms.
Good luck.