AGENESIS OF THE DUCTUS VENOSUS--A CASE WITH NOONAN SYNDROME.

BYO. DEMIRCI', T YAVUZ2, R. AR1S0Y', 0. PEKIN', H. ACAR H. AYDIN3, A. CETINKAYA3, A. KARAMAN3, E. ERDOGDU1 AND P KUMRU1A 39-years-old women, gravida 2, para 1 was referred to our center for evaluation of cardiomegaly at the 22nd gestational week. In the echocardiographie examination, the four-chamber view revealed moderate cardiomegaly, increased left cardiac axis and small pericardial effusion. We could not visualize the umbilical vein and ductus venosus in their usual location. We demonstrated agenesis of venous duct with extrahepatic shunt from umbilical vein (UV) to the right internal iliac vein. There was a dilatation of iliac vein and the whole inferior vena cava. This was diagnosed in the midsagittal view of the fetal trunk by two-dimensional (2D) imaging using the color Doppler mode, performed on Voluson 730 Expert and Pro (GE Healthcare, Milwaukee, WI). We did not find cardiac and extracardiac anomalies without agenesis of venous duct. Also, we found polyhydramnios. The parents did not agree to undergo chromosomal analysis. We followed patients for possible fetal heart failure every two or three weeks. At 34th week dysplastic pulmonary valve and mild pulmonary stenoses was found. After this findings and suspicious maternal facial appearance, we performed genetic counseling for the parents because of suspicion of Noonan syndrome. The molecular genetic testing for PTPN11 gene mutation, typical for Noonan syndrome, was performed in the mother. The baby was delivered at the 36th week of pregnancy because of spontaneous labor. A 2425 gram male infant was born by caesarean section due to fetal malpresentation. Postnatal confirmation of ductus venosus agenesis and abnormal course of umbilical vein was done with the umbilical vein cannulation and the path of the agitated saline shown by the ultrasound simultaneously. The same mutation of Noonan syndrome in the mother was detected in the baby postnatally. Also, progressive hypertrophic bilateral cardiomyopathy developed during the neonatal follow-up. Father and first sibling did not have any mutation for Noonan syndrome.Noonan syndrome is a common genetic syndrome characterized by short stature, congenital heart defect and typical facial appearance. Prenatally, Noonan syndrome should be considered in cases of ultrasound findings such as hydrops fetalis, cystic hygroma, increased nuchal translucency, pleural effusion, ascites, polyhydramnios and congenital heart disease with a normal karyotype (1,4, 7). In recent years, increased diagnosis of agenesis of ductus venosus due to increased interest in fetal venous system allowed us to understand its association with Noonan syndrome (2). In the present case, the diagnosis of ductus venosus agenesis with connection of the right iliac vein was made at 22 weeks of gestation. This case had normal nuchal translucency in the first trimester. We did not find cardiac and extracardiac anomalies without agenesis of ductus venous. There were moderate cardiomegaly, increased left cardiac axis and small pericardial effusion. The reason of the cardiomegaly is explained by cardiac overloading. Normally the ductus venosus drains between 25-30% umbilical venous blood towards the left atrium while the remaining placental blood flows into the portal system (13). But, in the agenesis of ductus venosus with extrahepatic umbilical venous drainage, all umbilical venous blood is delivered into the heart by inferior vena cava as in the present case. In addition, we detected pulmonary stenosis with dysplastic leaflets at late pregnancy and progressive hypertrophic cardiomyopathy postnatally. Similarly, Volpe et al. reported a Noonan syndrome with ductus venosus agenesis with connection of iliac vein and pulmonary valve stenosis (9). Valvar pulmonary stenosis with dyplastic leaflets is reported as the most common congenital heart defect (50-62%) with Noonan syndrome and hypertrophic cardiomyopathy found in 20% of patients (5, 6, 8). Both pulmonary stenosis and hypertrophic cardiomyopathy are more rarely found simultaneously as in our case (5). …