Once the child is in the catheterization suite, the monitor will be reconnected and the routine catheterization procedures will proceed. After the standard sheath for catheterization is placed in the child, a routine superior vena cava saturation (COOX) will be drawn and the NIRS reading along with routine vital signs will be documented. At the same time the routine saturation is drawn, an additional 2ccs of blood will be drawn for a lactate level. At 3 and 5 minutes after the routine saturation, a COOX will be drawn and the NIRS reading along with vital signs will be documented. The catheterization will continue as usual. At the end of the case, a final NIRS reading and vital signs will be documented prior to the removal of the probes.