Glossary for Adult Congenital Heart Disease, O—O

orthotopic

Located in an anatomically normal recipient site, often in reference to transplantation of an organ.

ostium primum ASD

See atrial septal defect.

outlet VSD

See ventricular septal defect.

over-and-under ventricles

See supero-inferior heart.

overriding valve

An A-V valve that empties into both ventricles or a semilunar valve that originates from both ventricles.