Unguarded tricuspid orifice: a rare malformation of tricuspid valve diagnosed by echocardiography. Report of two cases and review of the literature.

In this report we present two cases with unguarded tricuspid orifice, and review the literature. The complete absence of tricuspid valvular structures is a very rare anomaly coexisting with pulmonary atresia and intact ventricular septum, and is termed unguarded tricuspid orifice. Double tricuspid orifices and isolated dextrocardia were distinguishing features of our first case. The second patient of this report, a 5-year-old boy, is the first case in the literature with this malformation of the tricuspid valve as an isolated anomaly, in addition to being the first surviving case in the literature.