Thrombin Generation in Neonates

Children having open heart surgery must be on a heart-lung bypass machine. It is essential that the blood in the heart-lung machine does not clot. This is accomplished by giving a drug called heparin, a "blood thinner". The process of making a clot involves a lot of steps. One of the steps involves a protein called thrombin. Heparin acts on thrombin to keep blood from clotting. A technique has been developed to measure the blood's ability to generate thrombin. The bloods's ability to generate thrombin is measured by a thrombin generation curve (TGC). This curve would be very helpful to know when choosing the dose of heparin. We haven't found any studies using TGC in babies less than a month old. We want to do a study comparing the TGC in 10 newborns without a heart defect to the TGC in 10 newborns with a congenital heart defect. To do this we will need one sample of blood. the sample we need is 3 cc which is a little more than 1/2 teaspoon. The blood sample for both groups is to be taken from the intravenous catheter (IV) the child will have placed for surgery. The newborns without a heart defect will be children having surgery for a non-cardiac problem.