Double-chambered right ventricle and Down's syndrome: a proposed new association.

Twenty-two cases of double-chambered right ventricle studied in detail from two different centers comprise the study population. Of these, 5 have trisomy-21 Down's syndrome; these five cases, comprising nearly 25% of the entire study group, were essentially evenly divided between the two centers. This unexpectedly high percentage of Down's syndrome associated with such an unusual cardiovascular malformation, albeit among a small population, is likened to the currently recognized and similar association of Down's syndrome and atrioventricular cushion deformities.