Hi Holly :)
Gee I am so sorry to hear of your problems. I know that you are scared and you have a right to be. You're just a young lady with young children. This is really a young ladie's malady, from what reading I have done on the subject. MVP that is.
I have looked at it a bit and can say that most women aren't ever really bothered by MVP. Maybe some arrhythmias, or occasional chest pain. I am just a lay man, when it comes to medicine, so this is all just opinion. I must have this also because I have mild mitral valve regurgitation, or MVR.
I say this because MVP, leads to MVR, sometimes, but not always. Regurgitation results when the valve, in this case the mitral valve, prolapses or protrudes up into the left atrium of the heart. This causes blood to flow back-wards, from the big pumper (the left ventricle) into the left atrium, when it should not. The mitral valve should close tight, when the left ventricle contracts, so the blood will flow out of your aorta to your big toe and all else places :) This is where the complications start, when moderate to severe MVR occurs. Blood flow coming from your lungs, runs into the blood leaking back from the big pumper (LV), through your left atrium. This can impede blood flow through your lungs.
Now I assume the stress test was ok? Your doctor may have actually seen MVR, instead of MVP. I do not want to alarm you at all, but I do not see why he would want you to have a TEE (transesophageal echocardiogram) test, if he did not see any leakage past your mitral valve, on your previous echocardiogram. Do you? Ask him if there was any amount of MVR seen on your last echo.
I haven't had a TEE test, but I have had two endoscopic analysis's. No fair though, I got to be heavily sedated. They may want you as sober as possible....I think all they do is place a transducer, or ultrasound emitter down your goozle and take a really, really good look at those valves in your ticker. It gets the rear view, because it is behind your heart. If you have one of these test, get and keep you a copy. Pay extra for the film, if you have to. Did you know that these test are done prior to heart valve surgery, in order to make sure of very specific valve locations and conditions?
Best of luck to you and yours,