Abnormal Brain Structure and Function in Newborns With Complex Congenital Heart Defects Before Open Heart Surgery: A Review of the Evidence

Abstract

Newborns with complex congenital heart defects are at high risk for developing neurological abnormalities. It is important to understand the timing, progression, and extent of these abnormalities to better elucidate their potential impact on neurodevelopment, and their implications for early screening and intervention. This review synthesizes the recent literature describing neurological and neurobehavioral abnormalities observed in fetuses and newborns before cardiac surgery. A considerable proportion of newborns with complex congenital heart defects exhibit neurobehavioral and electrophysiological abnormalities preoperatively. Likewise, conventional neuroimaging studies reported that a high percentage of this population experienced brain injury. Advanced neuroimaging modalities indicated that fetuses showed delayed third trimester brain growth, and newborns showed impaired white matter maturation, reduced N-acetylaspartate, and increased lactate. These findings suggest a fetal or early postnatal onset of impaired brain growth and development. Consequently, reliable methods for early screening and subsequent developmental intervention must be implemented.

Severe Congenital Heart Defects Are Associated with Global Reduction of Neonatal Brain Volumes

“…19 White matter development is altered prior to surgery in infants with CHD compared with control infants on diffusion tensor imaging MRI studies. 10,11,20,24 In addition to altered brain development, white matter injuries and strokes can be detected on presurgical MRI scans. 8,10,22,25 This emphasizes the vulnerability of the critical period of brain development in infants with severe CHD exposed to hypoxia-ischemia or other processes such as hypoperfusion.…”

Fetuses with Isolated Congenital Heart Defects Show Normal Cerebral and Extracerebral Fluid Volume Growth: A 3D Sonographic Study in the Second and Third Trimester

“…Neonatal ultrasound imaging studies demonstrate cerebral abnormalities in 15–75% of neonates with CHD prior to surgery [3-7]. Most cerebral findings in CHD newborns are mild, such as asymmetrical widened ventricles and increased extracerebral fluid.…”

Prevalence and Spectrum of In Utero Structural Brain Abnormalities in Fetuses with Complex Congenital Heart Disease

“…1,2 During the past decade, a growing body of evidence has demonstrated the high prevalence of preoperative brain imaging abnormalities in neonates with CHD, suggesting an antenatal origin in many cases. [3][4][5][6] More recently, our group has used quantitative MR imaging to demonstrate a progressive third-trimester deceleration in volumetric brain growth and metabolism in fetuses with CHD, 7 reduced volumes of gray (cortical and subcortical) and white matter, and significant delays in cortical gyrification and surface area in fetuses with hypoplastic left-heart syndrome (HLHS).…”