Congenitally unguarded tricuspid valve orifice with a giant right atrium and a massive clot in an asymptomatic adult.

Congenitally unguarded tricuspid valve orifice, a variant of tricuspid valve dysplasia, is a rare malformation with protean manifestations. This report describes an asymptomatic adult who, on echocardiographic examination ordered in view of an abnormal 12-lead surface electrocardiogram and plain chest X-ray, was found to have an unguarded tricuspid valve orifice with a giant right atrium (12 x 10 cm), intense spontaneous echo contrast and a large right atrial clot.