Acardiac Twin: A rare Complication of Monochorionic Monoamniotic Twin

Abstract

Acardiac malformation, also known as twin reversed arterial perfusion (TRAP) sequence, is a unique complication of monochorionic twinning., occurring with a reported incidence of 1 in 35 000 deliveries. It is characterized by lack of heart development associated with a spectrum of malformations and anomalies in one of the twins, which is perfused in a paradoxical retrograde fashion by a structurally normal ‘pump’ twin through a single artery-to-artery anastomosis. There is usually a normally formed donor twin who has features of heart failure as well as a recipient twin who lacks a heart (acardius) and various other structures.It is caused in the embryo by a large artery-to-artery placental shunt, often also accompanied by a vein-to-vein shunt. The common complications include congestive cardiac failure in the pump twin, polyhydramnios and preterm delivery.