A Case of Progressive Ductal Constriction in a Fetus
A 22-year-old woman, gravid 2, para 1-0-0-1, was referred to our institution for fetal echocardiography at 23 weeks of gestation because of abnormally looking great arterial arches. The pregnancy had not been complicated. The mother had not had any diseases or taken any drugs or herbal medications. There was no family history of congenital heart disease. Obstetric evaluation showed normal fetal growth, normal amount of amniotic fluid and normal placenta. The fetal echocardiography revealed the normal four chamber view, where two atria and two ventricles were normal in size and thickness (). The two atrioventricular valves moved normally. Two great arteries arose normally from the appropriate ventricles. The pulmonary and aortic valves looked normal and the size of the main pulmonary artery and aortic root was within normal limits. The aortic arch was normal in size and in location, but the ductal arch was not visualized in any views. The main pulmonary artery bifurcated into two branch pulmonary arteries but was not continuous with the DA (). However color Doppler examination showed a tortuous 'S' shaped ductus cuddled inside the aortic arch (). The DA joined the descending aorta with an obtuse angle and showed a flow signal from the main pulmonary artery to the descending aorta (). Color aliasing occurred along the course of the ductus but pulsed Doppler measurement of velocity was not attempted because of the poor angle of insonation. Flow velocity and waveforms of the two great arteries were within normal limits and no TR was found. A diagnosis of S-shaped DA with mild narrowing was made and follow up examination was arranged.\nA repeat examination was performed at 27 weeks of gestation and showed nearly the same findings as before. The RV was normal in size and thickness and no TR was noted. Because the DA was S-shaped, it was very difficult to assess size along the whole range of the DA. However, the color Doppler examination showed tortuous turbulent flow in the ductus and suggested mild obstruction. The sagittal section of the aortic arch showed a ductal junction through which low velocity forward flow from the DA to the descending aorta was noted. Obstetric evaluation showed that fetal growth was appropriate and the amniotic fluid index was adequate. No signs of hydrops were noted.\nThe third examination was performed at 33 weeks of gestation. The right atrium was big and the RV was hypertrophied and globular in shape. The intracavitary volume of the RV looked slightly smaller than normal because of the thick ventricular wall and hypertrophy of the trabeculations. The right ventricular endocardial lining and the chordae of the tricuspid valve were very bright (). Color Doppler examination showed moderate TR and its velocity was 4.5 m/sec (). Every attempt failed to demonstrate any flow through the ductus. In spite of the right ventricular overload, fetal growth was within normal range and there was no evidence of fetal hydrops.\nAfter a discussion, we decided to deliver the baby. A female infant weighing 2625 g was born at 34 weeks gestation by induced delivery. Apgar scores were 7 at 1 minute and 8 at 5 minutes. Symptoms and signs immediately after birth were tachypnea, chest retraction, grunting sound and low oxygen saturation. An echocardiography performed at 20 minutes after birth showed a small hypertrophied RV and increased echogenicity of the moderator band and chordae of tricuspid valve (). There was a moderate TR with a velocity of 3.7 m/sec (). The short axis view showed a hypertrophied RV (). The ductus was searched for but no ductus was found in 2-D and color images (). Shunt flow through the foramen ovale was mainly right to left (). She required respiratory support with a mechanical ventilator for the first 3 days. She was successfully weaned from the ventilator on her fourth day and discharged at 12 days old. Follow-up examination at the outpatient clinic showed that she did not have any cardiac symptoms or signs. Echocardiography taken at 2 months of age showed much improvement. The RV was nearly normal in size and thickness. Increased echogenicity of the RV was also nearly normalized. There remained TR with a velocity of 3.0 m/sec. At 7 months of age, all echocardiographic findings returned to normal with resolution of TR.