Neurodevelopmental Outcomes and Postoperative Hemodynamics in Children With Hypoplastic Left Heart Syndrome

Over the past twenty years, the field of congenital heart disease has been marked by globally improved survival after complex congenital heart surgery. These improved results are clearly multi-factorial and include advances in diagnostic technologies, surgical techniques, perfusion strategies, pharmacologic therapies and perioperative monitoring of tissue oxygen delivery.

Hypoplastic left heart syndrome (HLHS) represents an extreme form of complex congenital heart disease in which the infant has prolonged cyanosis and a single systemic right ventricle. Staged palliation beginning with surgery in the neonatal period is the most common approach to infants with HLHS. After initial surgical palliation, infants are critically ill due to ischemia/reperfusion injury from cardiopulmonary bypass, coronary ischemia attributed to diastolic runoff, reduced total ventricular mass, continued hypoxemia during a time of increased metabolic demands, and finally, the inherent inefficiency of parallel circulation. The presence of any one of these physiologic derangements places the infant with HLHS at great risk for ischemia, organ dysfunction, circulatory collapse and, even, death. Postoperative monitoring of venous oximetry and, more recently, near infrared spectroscopy, have identified periods of impaired oxygen delivery and ischemia, allowed for interventions that enhance oxygen delivery and improved survival after cardiac surgery. Although, an apparent relationship exists between oxygen delivery and survival after cardiac surgery, little data is available on the relationship between oxygen delivery and neurodevelopmental outcomes (inclusive of neurocognitive and neuropsychologic outcomes).

Preliminary data from our center has recently identified that reduced venous oximetry was associated with adverse neurodevelopmental outcome. These initial findings warrant further investigation of neurologic injury, specifically, how such morbidity relates to perioperative ischemia and cerebral oxygen delivery. Hence, the purpose of this study is to understand the relationship of perioperative tissue dysoxia and long-term neurodevelopmental morbidity in children subject to oxygen delivery at which neurodevelopment is compromised. Identification of a critical threshold that may be devastating to a child's neurodevelopment and quality of life would allow for early intervention, goal-directed therapy and ultimately, improve outcomes.