[Restrictive ostium secundum: a new fetal malformation syndrome]

Echocardiographic examination of a 23 weeks' hydropic fetus disclosed abnormal kinetics of the valve of the foramen ovale. This valve was constantly bulging out, dome-like, into the left atrium, and on TM-mode tracings in transatrial projection the alpha and beta peaks which occur respectively during the opening and closure of the atrioventricular valves throughout fetal life were missing. This anomaly suggested that the ostium secundum was restrictive; the foramen ovale itself was not restrictive. Such abnormal kinetics have not been encountered among 16 other cases of hydrops fetalis of cardiac or other origin, or in a control series of 81 normal fetuses, which clearly shows that the restriction was primitive. At birth, the child presented with aneurysm of the foramen ovale, probably due to the restrictive ostium secundum.