Hi Deb, I suffered with Vintricular Tachycardia for about 10 years and had a pacemaker defibulater. I just want to stop by and say that the new symptom of shortness of breath is probably tied to the Tachycardia.
A brief history of me is that at first I was in the "until it does " category. I first was diagnosed with CHF with a IF of 5 % after a flu bug cased fluid around my lungs to enlarge my heart and so a pacemaker was put in as a precaution and i was put on Amiodroine and a beta blocker. I think it was coreg. So for about 5 years I had no issues that I knew of and one night the pacemaker had to shock me when I went into an arrhythmia where my pulse rate went over 200. Now I mentioned this because when the heart speeds up (that's what Tachycardia means) there is not enough oxygen rich blood leaving the heart to satisfy your body so you feel like your out-of breath. That was always my first symptom of an arrhythmia ( it's when the heart is moving so fast blood basically stops flowing) so the out of breath your feeling may be that your heart is in a situation I just mentioned of an arrhythmia. Now arrhythmias actually are common even in health adults but the difference is with a healthy system it usually only last a few beats and my be felt like a skipped beat or you may not feel them at all.
For me one test to verify if I was in an arrhythmia was checking my pulse. And if it seemed very fast or I could not feel it I knew to just relax sit down and let my pacemaker take care of it.
So my suggestion is to seek the advice of a cardiologist and if you believe it's electricial in nature a regular cardiologist may recognize it but that's when I was referred to an EP Cardiologist. EP stands for electro physiologist or a cardiologist that specializes in the electrical parts of the heart and most time that's where arrhythmia start, its a misfiring of the signals to cause the heart to beat. It gets out of sequence and they know how to fix those types of issues. I hope that helps and please let me know if I can help further. There are many was it can be kept under control so don't worry at this point. It could be something very easy to fix.
Blessings