What patient-specific characteristic places a newborn with hypoplastic left heart syndrome (HLHS) at highest risk for neurodevelopmental disability at 1 year of age?

Gestational Age of 36 Weeks Places a Newborn with HLHS at Highest Risk for Neurodevelopmental Disability

Based on the evidence, a gestational age of 36 weeks places this newborn with hypoplastic left heart syndrome at highest risk for neurodevelopmental disability at 1 year of age. 1

Risk Factors for Neurodevelopmental Disability in HLHS

Prematurity as a Critical Risk Factor

• Premature infants (less than 37 weeks), especially late-preterm infants (34-36 weeks), are at significantly increased risk for developmental delay compared to term infants 1
• Late-preterm infants without CHD have been shown to have the same risk for developmental delay as very preterm infants and are at significant risk for requiring early intervention services at 12 months of age 1
• Lower gestational age is directly associated with developmental disabilities in the complex CHD population 1
• Recent studies have demonstrated that delivery of neonates with critical CHD before 39 weeks' gestation is associated with greater mortality, morbidity, and resource use at progressively earlier gestational ages 1

Analysis of the Answer Options

Gestational Age of 36 Weeks

• At 36 weeks, this infant falls into the late-preterm category (34-36 weeks), which carries significant risk for neurodevelopmental disability 1
• Late-preterm infants with CHD have compounded risk due to both prematurity and cardiac disease 1, 2

Ascending Aorta Size of 5 mm

• While a smaller ascending aorta has been associated with worse outcomes in some studies, a 5 mm size is not specifically identified as a critical threshold for significantly increased risk 3
• The American Heart Association guidelines do not specifically identify ascending aorta size of 5 mm as a major risk factor for neurodevelopmental disability 1

Birth Weight of 3.5 kg

• This is within normal range for term infants and not considered a risk factor 1
• Low birth weight (especially <1500g) is associated with developmental delay, but 3.5 kg is appropriate 1

Shorter Time from Birth to Surgery

• While timing of surgery can impact outcomes, it is not identified as a primary risk factor compared to prematurity in the available evidence 1, 2
• The American Heart Association guidelines emphasize patient-specific characteristics like prematurity over surgical timing when assessing neurodevelopmental risk 1

Clinical Implications

• Premature infants with HLHS require heightened developmental screening and evaluation 1, 2
• The combination of prematurity and complex CHD creates a compounded risk for neurodevelopmental disability 1
• Regular neurodevelopmental surveillance, screening, and evaluation are essential for all HLHS patients, particularly those born prematurely 2
• Early intervention services should be strongly considered for premature infants with HLHS 2

Important Considerations

• Brain maturation in full-term neonates with CHD has been shown to be delayed, with an average brain maturation of only 35 weeks' gestation even in term infants 1
• When prematurity is added to this baseline delay in brain maturation, the risk for neurodevelopmental disability increases significantly 1
• The American Heart Association recommends that all children with HLHS be categorized as high-risk for developmental disorders, with additional risk factors like prematurity further increasing this risk 2