My youngest son has a Congenital Heart Defect which was picked up when he was 9 days old. He has an arrythmia problem (Supraventricular Tachycardia) and I know there are other mums here on Huggies that have CHD kids. There are so many CHD's and variations of each condition that it's hard to direct you to any relevant information without the actual diagnosis....and that can't sometimes be definite until after bub is born.
One thing I do recommend you do is go to HeartKids
and read through the information on CHD's they have there. They also have links to many pages with information as well as the contact details for HeartKids in each state. It's free to join HeartKids ...they are a family support and advocacy group....and the support they provide is invaluable. HeartKids also have Facebook pages for most states with many more links to information, as well as heaps of other FB pages dedicated to CHD's.
I wish you all the best with the rest of your pregnancy and for the journey you are about to embark on. Having a child with a heart condition can be a rocky journey but it can also be filled with lots of fun.