Infants born at term with congenital heart disease show widespread brain abnormalities similar to those in preterm neonates, an imaging study of 57 newborns has shown.
These anomalies, are present well before the infants undergo cardiac surgery, reported Dr. Steven P. Miller of the University of California, San Francisco, and his associates. “Although most forms of congenital heart disease [CHD] are now amenable to early surgical repair, deficits that impair widespread neurodevelopmental domains are identified in up to half of childhood survivors: fine motor skills, visuospatial skills, and cognition, including memory, attention, and higher-order language skills,” they noted.
Most studies on the issue have focused on acute brain injury related to delivery or to the surgery and its support procedures, such as cardiopulmonary bypass and hypothermic circulatory arrest. The investigators hypothesized that instead, much of this brain injury predates the surgery. They used MRI, three-dimensional magnetic resonance spectroscopic (MRS) techniques, and spectroscopic and diffusion tensor imaging to prospectively examine the brains of 29 term infants with transposition of the great arteries, 12 with single-ventricle physiology, and 16 normal term infants.
The newborns with CHD showed altered brain metabolism and microstructure shortly after birth, before they underwent surgery. These abnormalities were present even in areas that showed no visible injury on regular MRI. In some cases where the infants appeared to have discrete lesions, the abnormalities in metabolism and microstructure were evident even in areas that appeared to be uninvolved. For example, MRS showed that the ratio of N-acetylaspartate to choline, which increases with maturation, was significantly lower in the newborns with CHD than in the controls.
This impairment was widespread “and did not conform to the pattern of brain injury that is typical of hypoxia-ischemia in term newborns,” so it was more likely due to longstanding abnormal brain development rather than to an acute injury, the investigators said (N. Engl. J. Med. 2007;357:1928–38).