Postoperative care of cardiac patients requires a comprehensive and multidisciplinary approach to critically ill patients with cardiac disease whose care requires a clear understanding of cardiovascular physiology. When a patient fails to progress along the projected course or decompensates acutely, prompt evaluation with bedside assessment, laboratory evaluation, and echocardiography is essential. When things do not add up, cardiac catheterization must be seriously considered. With continued advancements in the field of neonatal and pediatric postoperative cardiac care, continued improvements in overall outcomes for this specialized population are anticipated.