Decreased heart rate variability (HRV) is an independent predictor of increased morbidity and mortality in adults with various forms of heart disease including myocardial infarction, coronary heart disease, congestive heart failure, and chronic mitral regurgitation. There have been very few reports of HRV trends throughout the pediatric age range. The techniques used have varied and normal ranges have not been established. Few studies involve children older than the neonatal age group, and the reported values for HRV have varied widely. There have been only 2 reports on HRV in pediatric heart disease, neither of which used currently standard analysis techniques. Gordon et al¹¹ found that decreased ZHV measured as a “respiratory quotient’’