CARLOS GARCÍA GUEVARA, MAGELA DE LA CARIDAD ARALUCE CALDERÍUS, WILLIAM GARCÍA LUGO,
JAKELINE ARENCIBIA FAIFE, YALILI HERNÁNDEZ,
JUAN CARLOS MITZI.
Cardiocentro Pediátrico Docente William Soler
Altahabana, Boyeros, La Habana, Cuba. E-mail
Recibido 13-ENE-19 – ACEPTADO después de revisión el 07-FEBRERO-2019.
There are no conflicts of interest to disclose.
The absence of ductus venosus is an uncommon condition with a variable prognosis, which can vary from an isolated finding to causing foetal death. Furthermore, it may also be associated with other genetic anomalies and syndromes. In the absence of ductus venosus, the flow needs to find new pathways (extrahepatic or intrahepatic shunt). In this article, we present one clinical case, with one of the variants, without association to chromosomal diseases.
Ductus venosus (DV) is a significant fetal vascular structure that allows oxygenated blood to go directly from the umbilical vein to coronary and cerebral circulation through a preferential path through the foramen ovale. In its isthmic portion, it operates like a sphincter protecting the fetal heart from an excess of placental blood flow [1,2].
The agenesis of this shunt has been associated with chromosomal and genetic anomalies, structural defects and delay in growth among others [3,4]. Besides, it may originate cardiomegaly, heart failure, hydrops fetalis and fetal death . It is a rare anomaly and difficult to diagnose, with an incidence ranging from 1:556 to 1:2500 . When ductus is absent, the umbilical vein may drain directly into peripheral circulation, the right atrium or the coronary sinus (extrahepatic drainage), which presents a higher risk of producing heart failure and being associated to other anomalies; or it may coexist with hepatic circulation (intrahepatic drainage) [5-7].
Little is known on the consequences and clinical implications of ductus venosus agenesis (DVA), infrequent anomaly and with a variable prognosis, which led us to perform the report on this case.
Pregnant, 20-year-old woman, living in the province of Granma, with G2P0A1 (induced), with no personal or familial pathological history of congenital defects or genetic diseases, with normal alpha-fetoprotein and echocardiography during the first trimester. In the second trimester echocardiography, at 23.4 weeks of gestational age, ductus venosus agenesis (DVA) is suspected, with no associated structural anomalies, which led to her referral with 25 weeks to the national reference center for the prenatal diagnosis of congenital heart diseases (Cardiocentro Pediátrico William Soler), where the diagnosis is confirmed and the umbilical vein is observed draining directly into the inferior vena cava, not detecting associated cardiac anomalies. During the echocardiographic test, the presence of cardiomegaly became evident, with predominance of right chambers (Figure 1), and when performing the longitudinal view, the inferior vena cava was observed to present throughout its trajectory, a difference in size caused by umbilical vein drainage flowing directly into it, skipping liver circulation (Figure 2). During the continuation of pregnancy, there were no complications or echocardiographic changes. At 40.2 weeks, spontaneous delivery occurs, with the newborn baby being healthy, with proper weight and Apgar 9/9. The baby was assessed by a multidisciplinary team, performing different tests, and not finding associated structural anomalies.
Figure 1. Transverse, 4-chamber view, where cardiomegaly is observed,
with right chambers predominance.
Figure 2. A) Echocardiographic longitudinal view of the fetus, where the inferior vena cava is indicated, with a difference in the interior diameter throughout its trajectory, caused by umbilical vein drainage that flows directly into it, skipping hepatic circulation. B) Umbilical vein draining directly into the inferior vena cava.
The flow velocity waveform (FVW) test on ductus venosus (DV) is a common practice in many centers during the exploration in the 11+0 – 13+6 weeks, as it is not very complex or time-consuming for the assessment, as long as the operator is properly trained . The impossibility to obtain the color signal and characteristic triphasic FVW with anterograde flow along the cycle or detecting a pathological flow waveform (absent or reverse diastolic flow during atrial contraction) entails an indication to perform early morphological test, and even more so in the presence of other associated markers .
FVW is the consequence of a failure in the formation of critical anastomosis between the umbilical and vitelline veins, with no direct communication existing between the umbilical vein and the right heart, and thus blood is deviated through an aberrant vessel, to the extrahepatic portal veins (portosystemic shunt) such as the iliac artery, inferior vena cava, superior vena cava, or suprahepatic veins, to the right atrium, or directly to the coronary sinus or through an intrahepatic venous network (umbilico-hepatic shunt); with the latter being the most frequent finding .
It is a rare anomaly with a prevalence of up to 6/1000 tests and a very variable rate of associated malformations (25-65%); not just of heart diseases, but of any other location, as aneuploidy or genetic syndromes as Noonan’s [3-7]. Within the cardiac anomalies most frequently associated to DVA are atrial and ventricular septal defects, tricuspid atresia, double outlet right ventricle, pulmonary atresia, and transposition of the great vessels. Other anomalies commonly associated are those of the gastrointestinal tract (duodenal atresia and tracheoesophageal fistulae), those of the genitourinary system (hydronephrosis and ectopic kidney) and of the musculoskeletal system (hemivertebra and structural anomalies of the radius and the humerus).
As an isolated finding, it appears just 35-60% of times. In this scenario, prognosis is markedly more favorable with 80-100% of fetuses with absolutely normal evolution .
In 23 cases of DVA, Berg et al , found 15 cases affected by aneuploidy and/or major structural anomalies; in the remaining 8, there were no severe associated anomalies, with significantly more favorable evolution between those with intrahepatic drainage.
In another study conducted by Ayerza et al , 75% of the children studied with prenatal diagnosis of DVA (9/12) also presented extrahepatic drainage of the umbilical vein (6 of them in the right atrium) and 44.4% of these presented heart failure.
The presence of extrahepatic shunt has two consequences that are proposed as responsible for the worst outcome in these fetuses and newborn babies. First, volume enlargement responsible for congestive heart failure, and second, and not any less relevant, a possible hyperdevelopment of the liver due to volume steal during fetal life; even more so if the anomaly is associated with portal system alteration.
In up to 50% of cases, its association with portal vein agenesis has been described, or even partial or total agenesis of the portal system. Shen et al , point out the development of the portal system as the prenatal prognostic factor most relevant in cases of isolated DV agenesis. If vascular shunt is narrow, similar to the ductus, it helps according to these authors, to a normal portal development, which has a favorable implication in postnatal evolution. A thick shunt of the umbilical vein interior diameter is associated with a worse evolution according to these authors.
After the diagnosis of DVA, the anatomy of the fetal portal system should be then assessed, from the second half of the pregnancy, as it is not very difficult, but it is significantly prognostic.
During the assessment of the fetus during the first trimester, the evaluation of the ductus venosus (DV) should be the rule, due to the significance of ruling out associated morphological and genetic pathologies. It is important that before the suspicion of absence of DV, we should be accurate about the drainage variant, perform karyotyping and search for structural malformations and genetic diseases, as prognosis will depend on all these factors, both during intrauterine life and outside of it.
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