Case report

A 20-year-old woman, G1P0, with unremarkable history. Screening for down syndrome was normal. Our US examination at the first trimester and second trimester revealed the following findings:

Images 1 and 2 - 11 weeks of pregnancy: heart US examination at 1^st trimester is limited, however some elements can be examinated such as heart location in the thorax and heart axis. Colour doppler is also used to assess anterograde chamber filling and anterograde blood ejection through the output vessels. Here, heart location and axis are normal. Image 1 shows 4 chamber view with 2 ventricles with anterograde filling. Image 2 shows outflow tracts. The expected pattern would be a "V-shaped" image representing the ductus arteriosus joining the aorta. Instead of that, oddly here there is only one big tube showing an anterograde flow.

Video 1, and images 3 and 13 - 21 weeks of pregnancy: CIV = VSD, AP=PA. BIF=bifurcation.

Heart examination shows levocardy and situs solitus. Atrioventricular concordance, well balanced LV and RV, normal atrioventricular valves. Perimembranous subaortic VSD, left-to-right shunt. Malposition of the great arteries with both vessels arising from the RV: dextroposed aorta and left-sided aortic arch, smaller pulmonary trunk with normal left PA and right PA. Both great arteries have anterograde flow without stenosis, anterograde ductus arteriosus, which means this is not a ductus-dependant condition at birth. That is the description of a double outlet right ventricle, with subaortic VSD (the so called Fallot type). There is also a left persistent superior vena cava draining into the enlarged coronary sinus. Thymus is present (absence of thymus may suggest a 22q1.1 microdeletion- DiGeorge Syndrome).

DORV (double outlet right ventricle): both great arteries arise entirely or predominantly from the RV. Several types of DORV exist according to the location of the VSD, the spatial relationship of the great arteries and whether or not there is an outflow obstruction. Pulmonary stenosis is the most common associated cardiac anomaly. Chromosomal anomalies are found in some fetuses (12% up to 40%) such as trisomies 18,13 and 22q1.1 microdeletion (region in the long arm (q) of chromosome 22). Tetralogy of Fallot and transposition of the great arteries are two main differential diagnoses for DORV. Subpulmonic VSD and aortic coarctation are associated with suboptimal postsurgical outcomes in DORV.

References

Alfred Abuhamad, Rabih Chaoui. A Practical Guide to Fetal Echocardiography. (2019) ISBN: 9780781797573