Prevalence, Spectrum, and Outcome of Right Ventricular Outflow Tract Abnormalities in Twin-twin Transfusion Syndrome: A Large, Single-center Experience.

OBJECTIVES

Twin-twin transfusion syndrome is a serious complication in 10-20% of monochorionic diamniotic (or higher) twin gestations. Cardiac changes in the "recipient" twin in twin-twin transfusion can include anatomic and functional abnormalities of the right ventricular outflow tract, which have only been described in several small series. It was the aim of this study to evaluate the incidence and outcome of right ventricular outflow tract abnormalities in a large cohort of twin-twin transfusion cases seen at a single referral center.

METHODS

A retrospective review of all cases of twin-twin transfusion syndrome seen in our center between 2004 and 2010 was performed. Fetal echocardiographic findings were reviewed, and the presence of right ventricular outflow tract abnormalities--including functional/anatomic pulmonary atresia, pulmonary stenosis, or isolated pulmonary insufficiency--was noted. Impact of selective fetoscopic laser therapy on right ventricular outflow tract abnormality and postnatal outcomes with regard to survival and residual right ventricular outflow tract abnormality were ascertained by review of medical records and telephone interview.

RESULTS

Right ventricular outflow tract abnormalities were observed in 53/610 (8.7%) of recipient twins but in no donor twins. Pulmonary atresia (24/53, 45%) was most common, followed by pulmonary stenosis (16/53, 30%) and isolated pulmonary insufficiency (13/53, 25%). Fetal therapy resulted in acute improvements in 10/42 recipient twins following selective fetoscopic laser therapy, but persistent right ventricular outflow tract abnormality was noted in 33% of recipient twins surviving to birth.

CONCLUSIONS

Right ventricular outflow tract abnormalities impact ∼ 9% of recipient twins in twin-twin transfusion syndrome, many of whom will have persistent abnormalities despite otherwise successful therapy. These data justify efforts to increase awareness and monitoring of the cardiac sequelae of twin-twin transfusion syndrome in these high-risk pregnancies.