Prenatal Diagnosis of Isolated Redundant Foramen Ovale: A Case Report

Abstract

Redundant foramen ovale (RFO) is defined as an abnormally redundant foramen ovale flap that extends at least halfway across the left atrium. The exact pathogenesis is unknown. Premature, isolated, in utero RFO is rare. The prevalence in general population is unknown as it may be easily ignored on routine fetal echocardiography. The reported frequency in fetuses referred for echocardiographic examination is 0.6–1.7%. It can cause right ventricular volume overload leading to fetal hydrops and subsequent cardiac failure. In such cases, prompt delivery depending on fetal gestational age may be instrumental for the survival of the neonate. 67% can develop cardiac arrhythmias which generally resolves at birth. The most common is premature atrial contractions though rarely, supraventricular tachycardia can also occur. RFO usually occurs in isolation but when associated with congenital heart disease, it carries a poor prognosis. Several series have reported redundant foramen ovale in echocardiographic and autopsy findings in children and adults but only few reports on the antenatal detection of isolated RFO has been described. We discuss two prenatal cases of isolated redundant foramen ovale diagnosed in the third trimester. They were followed up two weekly without development of any complications and delivered at term. After delivery, the infants had no history or symptoms of cardiac distress. Echocardiography showed a structurally normal heart. Hence, if there are no associated anomalies in a case of redundant foramen ovale, the prenatal management need not be altered.