Prior work on a small number of children shows that PCT increases shortly just from heart surgery itself, even without infection. There is little information published about how accurate PCT is for identifying infection in the child heart population. In order to use PCT in our patients, we need to know what the normal levels of PCT are after surgery. Thus, when an infection does happen, we can identify it. We also need to take PCT levels when patients are thought to have infections. We will then need to watch for an infection over the next few days to see if the PCT level rises and can actually predict the presence an infection.