Optimal treatment for the neonate who presents with transposition of the great arteries {S,D,D}* and intact ventricular septum includes:

A. PGE 1 infusion to maintain duct patency.

B. Administration of intravenous fluid to increase intravascular volume.

E. Atrial balloon septostomy to improve atrial mixing.

DISCUSSION: Because with transposition of the great vessels the systemic and the pulmonary circulations exist in parallel rather than in series, survival depends on mixing between pulmonary and systemic circulations. Initially infants with transposition and intact atrial septum survive because of aortopulmonary flow through PDA, which may be maintained with prostaglandin infusions. Although increased pulmonary flow may cause enlargement of the left atrium and stretching of the foramen ovale resulting in atrial-level mixing of oxygenated and nonoxygenated blood, inadequate mixing at the atrial level will result in marginal tissue oxygenation, which does not improve with oxygen administration. Atrial balloon septotomy results in improved admixture and oxygen delivery in these patients and should be performed promptly if peripheral acidemia and severe cyanosis are present. Relative dehydration may decrease the degree of interatrial shunting and volume infusion often improves hemodynamics in infants. Decreased pulmonary vascular resistance may increase pulmonary blood flow at the expense of systemic blood flow and alter the loading conditions of the left ventricle, which may complicate early arterial repair.