A heart with three arterial trunks (tritruncal heart). Report of a case.

The case is described of a 4 1/2-year-old girl with a previously unreported malformation: a heart with three arterial trunks, aorta, main pulmonary artery, and an intermediate vessel, called "intermediate trunk" because it was situated between the aorta and the main pulmonary artery. Each of these three arteries had a semilunar valve at its origin, and their lumens were completely separated from each other. The pulmonary trunk arose from the right ventricle, while the aorta and the intermediate trunk arose from the left ventricle. The intermediate trunk continued as the right pulmonary artery. The pulmonary trunk continued as the left pulmonary artery. The outflow tracts of both ventricles were normal. There were therefore three arterial trunks arising from a heart with two outflow tracts. Our hypothesis on the embryopathogenesis of this case is that there was double septation of the primitive arterial trunk and the aortic sac, without involvement of the conus. In addition, there was a malalignment between the truncal and conal septa. This entity, however rare, should be considered in the differential diagnosis of absent or anomalous right pulmonary artery.