Did you know that a baby's heart forms and begins to beat in the first 26 days of prenancy? So sometimes even before a woman is aware she is pregnant, her baby's heart is already beating. It makes the heart a very vulnerable organ very early.
The heart itself is a pivital but pretty simple and remarkable part of the pumping system. Blood is brought into the right atria (on the top) from the two largest veins in the body the inferior vena cava, and superior venan cava. The blood is pumped through the tricuspid valve down into the right ventricle. The right ventricle pumps the blood throught the pulmonary artery (the only artery in the body that carries non-oxygenated bood) out to the lungs. There, it dumps off carbon dioxide and picks up oxygen before being shuttled back to the heart through the pulmonary vein back to the left atria. From there the now oxygenated blood goes through the mitral valve into the left ventricle. The left ventricle, the hearts primary pump, then pumps the blood out through the aorta and out to the body. It all happens with each heartbeat.
All that said, there are only 5 primary heart defects that make a baby blue at birth. They were taught to me as the five T's.
1. Tetrology of Fallot
2. Tricuspid Atresia
3. Transposition of the great vessels
4. Total anomalous pulmonary veinous return
5. Truncous Arteriosis
Tricupid Atresia and Transposition of the great vessels are both fairly simple disorders for the most part, however, only the latter can be effectively corrected.
Tetrology of Fallot, as it's name implies has, 4 parts; all can be corrected.
The final 2 are more complex and difficult to correct. Truncous arterious is exactly what it's name implies. The heart doesn't form correctly, and the baby has only a rudimentary heart with two chambers. There are some procedures but even now it's a hard one to treat. TAPVR (total anomalous venous return) is very complex and involved finding all the the areas of the heart where blood is returned from the lungs.
If anyone has interest in individual defects I would be happy to go into more detail. I have been a nurse for 28 years.