Plasma amino acids in interrupted aortic arch and the hypoplastic left heart syndrome.

Plasma amino acids were measured in 8 babies with left-sided congenital heart disease, 3 interrupted aortic arch (IAA) and 5 hypoplastic left heart syndrome (HLH), at 1-6 days of age. There was an increase in total amino acid levels when compared with 40 control infants of similar gestational age and birth weight. Both branched-chain and aromatic amino acids were raised although there were differences between the babies with IAA and HLH. Babies with HLH had higher total amino acid levels than babies with IAA, the difference being due to raised branched-chain amino acids. Apart from the anatomical differences babies with HLH had metabolic acidosis at the time of sampling whereas babies with IAA had normal pH. It is possible that the increase in amino acid levels in babies with obstructed left-sided congenital heart disease is due to hepatic congestion and hypoperfusion, although altered acid base states may also be important.