 Heart transplantation is the only hope for children with end stage heart disease. Eventually cardiac deterioration occurs and leads to death or re-transplantation. Our understanding of the pathophysiology of cardiac dysfunction in these children is incomplete. The time course of the dysfunction process either in the RV andor the LV, systole or diastole has never been studied in children. No meaningful TSI quantitation has ever been performed in a large pediatric OHT patient population. The long-term goal of this study will be the detection of functional myocardial changes associated with known stages post heart transplantation using TDI and TSI. These achievements impact the survival and quality of life of children after cardiac transplantation. 