An infant with two "half-hearts" who survived for five days: a clinical and pathological report.

The case of a five-day-old boy with two "half-hearts," diagnosed at necropsy but not clinically, is presented. Each "half-heart" was totally separated from the other and each had a single atrium and ventricle. The two "half-hearts" were enveloped in a common pericardium. The left-sided atrium and the right-sided atrium had the morphologic characteristics of left and right atrium, respectively, but the morphology of the two ventricles was less characteristic. There were double truncuses and double superior and inferior venae cavae, too. Pulmonary venous drainage was totally anomalous; splenic abnormalities were not found. An embryologic lack of fusion of the primitive cardiac tubes is a possible starting point for these malformations.