Newborns with heart defect have low blood flow in brain before surgery

12/07/04

As survival rates have steadily improved for children with heart defects, physicians have focused more attention on improving quality-of-life factors such as neurological and cognitive abilities. A new study shows that newborns with congenital heart disease often have abnormally low blood flow in their brains before they undergo surgery.

Researchers from The Children's Hospital of Philadelphia led the study, published in the December issue of The Journal of Thoracic and Cardiovascular Surgery.

One of every 100 children is born with a heart defect--one-third of which are severe enough to require surgery during the newborn period. Many of those high-risk children are identified as having neurological and cognitive problems during the months and years that follow. While some of these problems may be related to the complexity of the surgery, evidence is mounting that abnormal neurological conditions play a role even before surgery.

The current study, which used a novel magnetic resonance imaging (MRI) technique developed by members of the investigative team, was the first to measure the infants' cerebral blood flow before surgery. The reduced blood flow was associated with abnormal features in the newborn brain, according to pediatric neurologist Daniel J. Licht, M.D., who led the multidisciplinary research team at Children's Hospital.

"Some of the neurodevelopmental problems that these children experience may be attributable to necessary surgical practices such as heart-lung bypass," said Dr. Licht. "However, many infants with heart defects have neurological abnormalities before surgery."

The research team at The Children's Hospital of Philadelphia studied 25 newborns born at term with congenital heart defects. They found cerebral blood flow to be significantly lower than in healthy newborns, sometimes drastically reduced. The low blood flow was also associated with a condition called periventricular leukomalacia (PVL), a scarring of white matter in the brain. PVL has often been linked to neurological problems such as attention deficit-hyperactivity disorder in infants without heart disease. More severe forms of PVL have been associated with cerebral palsy in infants who are born prematurely.

A previous study by the same multidisciplinary team at Children's Hospital found PVL to be common before surgery in newborns with congenital heart disease. The current study could not determine whether the low blood flow levels caused the PVL, but those levels may be useful in guiding future treatments. "If we can define early markers for injury severity or injury risk, we may be able to better identify newborn babies who could benefit from protective therapies, thereby improving their quality of life," said Dr. Licht.

Dr. Licht is a Pfizer Scholar and is also supported by the W.W. Smith Charitable Trust. Dr. Licht's co-authors were Jiongjiong Wang, Ph.D., David W. Silverstre, B.S., Susan C. Nicolson, M.D., Lisa M. Montenegro, M.D., Gil Wernovsky, M.D., Sarah Tabbutt, M.D., Ph.D., Suzanne M. Durning, R.R.T., David M. Shera, Ph.D., J. William Gaynor, M.D., Thomas L. Spray, M.D., Robert R. Clancy, M.D., and Robert A. Zimmerman, M.D., all from the Neuro-Cardiac Research Program of The Children's Hospital of Philadelphia, and John A. Detre, M.D., of the Hospital of the University of Pennsylvania.

Source: Eurekalert & others

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