Troponin levels have been well demonstrated to indicate damage to the myocardium and are occasionally used in the immediate post-operative period following pediatric cardiac surgery to evaluate degree of myocardial injury. Thus far, no study has established normal range of troponin values in children undergoing cardiac surgery and hterefore, it is difficult to interpret the results. We propose to establish a spectrum of normal post-operative troponin levels in children undergoing various types of cardiac surgery to establish baseline values for comparison in these patients.