Neurocognitive Disability Is a Long-Term Consequence of Congenital Heart Surgery

According to Dr. Licht, results of two hemodilution studies from Boston show that the volume of whole blood needed to prime the pump before surgery can influence outcomes. Typical pump volume is at 400 cc normal saline, versus a blood volume of 250 cc in a 3-kg infant. Thus, priming the pump with saline causes hematocrit levels to decrease to 20%. Trial 1 involved 147 patients randomized to have a hematocrit of 20% to 30%. Infants with a hematocrit of 20% had decreased psychomotor development. Trial 2 involved 124 infants with hematocrits at 25% to 35%. There were no differences between groups. A combined analysis of trials 1 and 2 found that a hematocrit below 25% was associated with poorer outcomes. Thus, the goal at surgery should be a hematocrit of 30%.

Dr. Licht compared the one-year outcomes of five studies involving 462 arterial switch patients. Mental developmental index and psychomotor developmental index scores were essentially the same for all studies, suggesting that factors other than the heart surgery may underlie the cognitive deficits. “The [surgical] factors that are modifiable do not change the outcome,” he hypothesized.

Long-term studies of neurodevelopmental outcomes of PVL are needed in congenital heart patients, as are pharmacologic neuroprotection studies in neonates, stressed Dr. Licht. He suggested that PVL might be a surrogate marker for long-term outcome.