Cardiac Metabolism in the Fetus and Newborn

The heart undergoes marked changes in energy substrate availability, utilization, and metabolic activity during the transition from the fetal to postnatal environment. Availability of these substrates to the newborn is dependent on adequate gas exchange in the lungs, coronary blood flow, and, after a period of time, enteral or parenteral intake of nutrients. At birth, a rapid shift from carbohydrate to fatty acid utilization occurs. However, in the presence of oxygen insufficiency, the neonatal heart retains the capacity to maintain anaerobic energy production and, thus, cardiac function. Despite the importance of adequate cardiac function and the frequency of neonatal hypoxemic conditions, relatively little is known about how the lack of oxygen affects neonatal cardiac function. More studies are required to discern the optimal nutritional management of infants at risk of suffering from myocardial injury related to oxygen deprivation or other alterations of the fetal and postnatal environment.