Unfortunately, you haven't given us enough specific details with respect to possible reflux symptoms to really comment. The way you've described yourself and you symptoms, I can see why your doctors have suspected something with your cardiovascular system.
What about typical reflux symptoms? Have you tried managing it with some behavior adjustments (i.e. sleeping on an incline, not eating within 4+ hours of bed, etc.), and noticed any change? Do antacids offer any relief?
If you do some of this investigating on your own, and evaluate your own response, you'll give your doctors more to go on. There are a couple of links at the top of the main page of this messageboard that can get you started.
-Bruce