Sinus venosus defects: unroofing of the right pulmonary veins--anatomic and echocardiographic findings and surgical treatment.

To clarify the nature of so-called sinus venosus atrial septal defects, the echocardiographic findings in 41 patients undergoing surgery at Children's Hospital, Boston, from March 1986 to October 1992 were reviewed, and four heart specimens with this anomaly were reassessed. Our conclusion, clearly demonstrated echocardiographically, is that sinus venosus defects result from a deficiency in the wall that normally separates the right pulmonary veins from the SVC and the RA. This deficiency unroofs the right pulmonary veins, permitting them to drain into the SVC or into the RA. An interatrial communication is almost always present and is posterior or posterosuperior to the fossa ovalis. This interatrial communication is the orifice of the unroofed right pulmonary veins rather than a defect in the atrial septum.