Acardia (Encyclopedia of Genetic Disorders)
Acardia is a very rare, serious malformation that occurs almost exclusively in monozygous twins (twins developing from a single egg). This condition results from artery to artery connections in the placenta causing a physically normal fetus to circulate blood for both itself and a severely malformed fetus whose heart regresses or is overtaken by the pump twin's heart.
Acardia was first described in the sixteenth century. Early references refer to acardia as chorioangiopagus parasiticus. It is now also called twin reversed arterial perfusion sequence, or TRAP sequence.
Acardia is the most extreme form of twin-twin transfusion syndrome. Twin-twin transfusion syndrome is a pregnancy complication in which twins abnormally share blood flow from the umbilical artery of one twin to the umbilical vein of the other. This abnormal connection can cause serious complications including loss of the pregnancy.
In acardiac twin pregnancies, blood vessels abnormally connect between the twins in the placenta. The placenta is the important interface of blood vessels between a mother and baby through which babies...
(The entire section is 1400 words.)
Want to Read More?
Subscribe now to read the rest of this article. Plus get complete access to 30,000+ study guides!