Persistence of the Embryonic Right Venous Valve

Courtesy of Dr. Leo Lopez (Children’s Hospital at Montefiore) and Dr. Elizabeth Welch (Miami Children’s Hospital)

In this modified subcostal view, a membranous structure is seen in the right atrial chamber billowing like a windsock into the tricuspid inflow and causing obstruction. The embryonic right venous valve of the sinus venosus normally regresses during the last 6 months of gestation and becomes the Eustachian and Thebesian valves. The abnormal structure in this image results from failure of this regression and can be related not only to obstruction at the right ventricular inflow but also to right ventricular hypoplasia.

Persistent 5th Arch Variant

Courtesy of Dr. Elizabeth Welch and Roque Ventura (Miami Children’s Hospital)

In this suprasternal long-axis view without and with color mapping, the aortic arch is visualized with narrowing and turbulence in flow in the area where the patent ductus arteriosus connects to the aorta, suggestive of aortic coarctation. There is an additional vessel located between the aortic arch and the ductal arch with to-and-fro flow because it has no connection to the distal transverse aortic arch or to the proximal descending aorta. This vessel probably represents a variant of a persistent 5th aortic arch (also known as a double lumen aortic arch) with interruption. This is unusual because, although aortic interruption can occur in the setting of a persistent 5th aortic arch, the interrupted segment is typically the normal 4th aortic arch and not the abnormal 5th aortic arch.