anatomy scan gone wrong

So I had my anatomy scan today (I'm 21 weeks) and they told me to come back in 4 weeks to re scan the heart as they don't know what's wrong with the heart vessels. I don't know what that means and I am freaking out. They told me to come back and then if it's the same (which it probably will be) they will send me to a specialist. 
The ultrasounder was nice but didn't give me much info neither did the doctors and nurses. I called the office 2 hours later explained to them I'm worried and they said they can't do anything until 4 weeks. 
Has anyone been told their child has a heart problem? I understand this is NOT the place to discuss abortion.. but I don't want one. From what I've read on google the drs basically said that their child would need a heart transplant and many of them die waiting. I just don't know what to do I'm sorry. 
Does anyone have any advise?