Although sudden infant death syndrome (SIDS) is a cause for sudden infant death, other causes should be ruled out before diagnosing SIDS. Cardiac causes for sudden infant death include viral myocarditis, congential heart disease particularly congential aortic stenosis, endocardial fibroelastosis, and anomalous origin of the left coronary artery from the pulmonary artery. Other cardiac conditions that may result in sudden death include rhabdomyomas of the heart in tuberous sclerosis and conduction system disorders. The most frequent conduction system disorders resulting in sudden death include histiocytoid cardiomyopathy, congential heart block that may be associated with maternal lupus erythematosus, arrhythmogenic right ventricular dysplasia, noncompaction of the left ventricle, and long QT syndromes.