Separation of Conjoined Twins with a Single Heart

Three-D computer modeling with prenatal magnetic resonance imaging (MRI) were used to assist the planning of the surgical separation, which involved a team of obstetricians, pediatric heart specialists, and radiologists from Children's Hospital and Brigham and Women's Hospital (Boston, MA, USA). Their work was performed in 1999 but was only recently reported in The New England Journal of Medicine (2000;343:399-402).

At 19 weeks' gestation, fetal echocardiography showed a normal heart in one twin, with its apex extending into the thorax of the other twin, called the acardiac twin. The acardiac twin had only a rudimentary cardiac structure, fed and drained by a single vessel. A single umbilical cord was also identified, with four arteries. When Doppler studies were performed, they revealed that blood flowed from the umbilical arteries of the twin with a heart to the acardiac twin, draining back to the twin with a heart through a single large ductus venosus passing through the fused livers. Apart from these, there were no other abnormalities.

The surgeons expected clinical instability after birth, since division of the umbilical cord would impair perfusion to the acardiac twin. Following cesarian delivery, they immediately began the surgical separation, as a result of which the acardiac twin died. The surgeons closed the ventral defect in the surviving twin, using the other twin's ribs to make a cage-like structure to protect her protuberant heart.