Before aggressive intervention, Mitchell found that 2.3 of 1,000 live births died with cardiac problems in infancy (1). Infant cardiac mortality in developed countries has progressively declined over the last several decades with better prenatal and postnatal recognition, and with the development and refinement of definitive interventions and peri-procedural management. The infant cardiac fatality rate in the United States was 0.15 per 1,000 births in 2000, ranking tenth among leading causes of infant death (4). At high-volume surgical centers more commonly occurring cyanotic cardiac anomalies such as transposition of the great arteries and tetralogy of Fallot have surgical mortality rates of 1% to 5% or less. Complex anomalies with the highest risk have also had significant improvements in neonatal survival in developed countries. For example, surgical survival of neonates with hypoplastic left heart syndrome increased from 40% to 60% to 75% to 93% at specialized surgical centers (5), with overall mortality in infancy approximately twice this. Although surgical surgery outcomes are much improved, including in babies with prematurity and multiple anomalies, prematurity and associated noncardiac anomalies still strongly influence the potential for salvaging infants with cardiac disease (Table 33-2) (4). In some situations, the mortality attributable to these problems is considerable.