Prolapsed valve of the foramen ovale in newborns and infants with coarctation of the aorta.

Out of 60 newborns and infants with symptomatic coarctation of the aorta, 34 had a significant left-to-right shunt at atrial level. In 20 of these 34 children, the atrial shunt had disappeared after surgical correction of the coarctation. All patients with this "reversible" shunt, thought to be secondary to an incompetent valve of the foramen ovale, were younger than 35 days at first cardiac catheterization. Left atrial pressure and left atrial volume of these patients did not differ significantly from those in a control group without atrial shunt. The conditions necessary for the development of a valve-incompetent foramen ovale include not only an increased left ventricular work load, but also a thin and pliable valve of the foramen ovale. It is only in infants younger than one month of age that the valve is thin and pliable enough to prolapse through the foramen ovale and form a channel between the two atria, which results in a left-to-right atrial shunt.