Premature narrowing of the foramen ovale is rare but serious clinical entity. Prenatal narrowing or obstruction of the foramen ovale shows symptoms such as right heart failure, fetal hydrops, triscupid regurgitation, left heart obstructive disease, and supraventricular tachycardia. This study aimed to assess the prenatal diagnosis and postnatal clinical course of restrictive foramen ovale in utero in otherwise normal heart.

The subjects were five patients diagnosed with restrictive foramen ovale in utero from January 2001 to June 2005 at Chungnam National University Hospital. The diagnostic criteria was defined when the maximum diameter in a 4-chamber view is less than 2.5 mm and there is a continuous doppler velocity at the foramen ovale of more than 0.6m/s.

At the time of diagnosis of restrictive foramen ovale, gestation age was 34~37 wks, and chief complaints were fetal arrhythmia(2 cases), pericardial effusion, Ebstein anomaly and subaortic stenosis. Two cases which were diagnosed fetal hydrops and supraventricular tachycardia delivered by emergent cesarian section. Five cases were found to have right heart dilatation on echocardiogram after birth, but right heart dilatation became normalized at day 7 after birth and the clinical courses were not eventful.

Identifying an obstructed foramen ovale in the fetus warrants the further search for additional cardiac and extracardiac anomalies, which may alter the prognosis. Delivery should be induced if possible in cases of foramen ovale obstruction with signs of cardiac decompensation.