Conjoined hearts.
Thoracopagus twins were delivered at 37 weeks' gestation by caesarean section. Respiratory distress was present and mechanical ventilation was needed; 36 hours after delivery severe lactic acidosis developed and the twins died. The pericardial sac was common and the hearts were conjoined as a single structure with ventricular fusion.
D005260:Female; D006330:Heart Defects, Congenital / Q000473:pathology*; D006801:Humans; D007231:Infant, Newborn; D014428:Twins, Conjoined / Q000473:pathology*