Hi there. I have had palpitations/PVC's since I was age 20. I am 35 now. I got pregnant in 2007. I had no palpitations AT ALL in my first and third trimesters. However, during my second trimester I had alot, all day long, for the entire three months of the trimester. Before I got pregnant, I took alot of supplements to try to control my palps. When I got pregnant, I stopped everything except a prenatal vitamin. When my palps returned with a vengence during the 2nd trimester, I asked my OB if I could resume taking my other supplements, including Mg. She told me not until I had (another) full, cardiac workup. So I did. Nothing was structurally wrong with my heart and no dangerous arrythmias were noted on the event monitor I had to use. So, they told me I just had to deal with it. And, I did. I have a beautiful and healthy 15-month-old little girl now. You'll be OK. Alot of the heart stuff that you are going through has to do with your hormones. And, when you are pregnant, your blood volume increases some 40%, so your heart is working extra hard. Just do what your doctor tells you to do, and be sure to speak up if you have any other changes that aren't normal to you. If you are exercising, maybe tone it down a notch or two for now. I wasn't able to exercise while pregnant because of other problems I was having with my pregnancy. As for the SOB, I had that too, bad. And, I had to sleep sitting up too!! It's most likely because your baby is sitting on your diaphragm. Or, if your tummy is quite big, then that could be it too. All the weight is sitting in one place, and not evenly distributed throughout your body. Makes life a little tough to get around, doesn't it? Well, it's only temporary. Hang in there. Soon, you will have a beautiful baby and all these physical nuisances will be gone. Good luck! Oh, I almost forgot. Mag oxide is one of the least effective kinds. I take chelated Mag glycinate. If you are allowed by your OB, try that one.
How is your blood pressure? According to the report your atria are above the normal range which could be fine or could be a sign of something (most often high blood pressure).
I agre with Jerry - speak to the Dr who ordered the echo - he/she should answer your questions and determine any necessary follow up.
Get an evaluation from your doctor.
I can say from the little I know that is nothing in your echo that says to me it would cause SOB or any symptoms you could feel.
This isn't a OB forum, but I wonder if you've gained too much weight or anything directly related to your pregnancy that could be the cause of you problems.
Good luck with your future delivery and life as a parent, your most important responsibility in the future.