Absent tricuspid valve with aortic atresia in mixed levocardia (atria situs solitus, L-loop). A hitherto undescribed entity.

Clinical, angiographic and pathologic features are described in a 36-hour-old male infant with mixed (discordant) levocardia, aortic valve atresia, absent tricuspid (left atrioventricular) valve and resultant massive cardiomegaly. This is the first reported case of this type of complex in a heart with discordant chambers. A possible embryologic explanation is offered for the concomitant presence of semilunar valve atresia and absence of the tricuspid valve.