Diagnosis and Management of Fetal Ductus Arteriosus Constriction

The ductus arteriosus is an important structure in the fetal circulation. It connects the pulmonary artery to the arch of the aorta distal to the origin of the left subclavian artery and carries most of the right ventricular output. Patency of the ductus arteriosus is maintained by factors like prostaglandin E2, nitric oxide and low oxygen tension of the blood. With the advent of ultrasonography and Spectral Doppler, many cases of ductal constriction have been reported. It can be idiopathic but is usually secondary to the use of medication like NSAIDs, isoxsuprine, fluoxetine and also some particular foods rich in polyphenol like herbal teas, dark chocolate, berries and coffee. Idiopathic ductal constriction is a rare finding. Ductus arteriosus constriction occurs largely due to inhibition of the prostaglandin synthetase pathway as the ductus arteriosus becomes more sensitive to prostaglandin inhibitors in later gestation. It is, therefore, more commonly seen in the 3rd trimester. Because of fetal hyperdynamic compromise, it results in tricuspid regurgitation, right ventricular hypertrophy and ultimately right ventricular failure, hydrops, pulmonary hypertension and even intrauterine fetal death. We present a series of ductus arteriosus constriction, of which 3 cases were associated with tricuspid regurgitation, 1 case with right sided dominance of the heart and 1 case with moderate to severe right ventricular hypertrophy. Mild cases require close fetal monitoring and severe cases may need urgent delivery. Postnatal prognosis seems to be good in cases of ductal constriction associated with right heart abnormalities as right heart abnormalities resolve in a couple of weeks, although pulmonary hypertension and right ventricular failure are major concerns. Preventive measures include avoiding the use of NSAIDs and other medications especially in the 3rd trimester and changes in maternal dietary habits.