Objective: The twin-twin transfusion syndrome (TTTS) complicates 10-30% of monochorionic pregnancies. The incidence of pulmonary stenosis and endocardial fibroelastosis is especially high in the recipient twin. We report a novel finding of four cases of coarctation of the aorta and hypoplastic aortic arch in the donor twin.

Methods: Retrospective review of tertiary referral neonatal database and mortality data from 2002 to 2007 with cross-validation from the local tertiary paediatric cardiology unit data (1998-2006) to identify children presenting with coarctation who were also twins.

Results: We identified four monochorionic twin pairs affected by the TTTS, delivered between 25 weeks to 36 weeks gestation, where the donor twin was found to have coarctation of the aorta or aortic arch hypoplasia. In addition, two of the four recipients also had cardiac abnormalities. There was a high mortality rate of 30% for both twins, and a high morbidity rate, especially for neurological sequelae.

Conclusion: We believe that the increased incidence of aortic arch abnormalities in the donor twins may be explained by the altered fetal blood flow and haemodynamics in TTTS with a relative decrease in left ventricular output due to decreased placental return. Given the increased prevalence of congenital heart disease in TTTS, with an increased risk for coarctation in the donor twin and pulmonary stenosis in the recipient, intrauterine surveillance and a postnatal comprehensive cardiac assessment for both twins is warranted.