[Remnants of the embryologic sinus venosus valves. "Cor triatriatum dexter" (author's transl)]

Remnants of the embryologic sinus venosus valves are not uncommon. However, persistent venous valves in the right atrium, which are large enough to obstruct the blood flow through the tricuspid valve (the so called cor triatriatum dexter) are very rare. There are 3 different types according to the location of the right atrial membrane. Right heart chambers hyoplasia is the most common association. Concurrent lesions of lesser degree have also been described. Although isolated cor triatriatum dexter could be symptomatic, both the clinical features and the prognosis usually are the consequence of the associated malformations. A review of the embryological aspects is offered.